Postoperative Hypotension after Noncardiac Surgery and the Association with Myocardial Injury

Impact on Patient Outcomes of Continuous Vital Sign Monitoring on Medical Wards: Propensity-Matched Analysis

BACKGROUND

Continuous and wireless vital sign (VS) monitoring on hospital wards is superior to intermittent VS monitoring at detecting VS abnormalities; however, the impact on clinical outcomes remains to be confirmed. A recent propensity-matched study of primary surgical patients found decreased odds of intensive care unit (ICU) admission and mortality in patients receiving continuous monitoring. Primary surgical patients are inherently different from their medical counterparts who typically have high morbidity, including frailty. Continuous monitoring research has been limited in primary medical patients.

OBJECTIVE

This study aims to evaluate the clinical outcomes of primary medical patients who received either continuous or, as a contemporaneous control, intermittent vital monitoring as the standard of care using propensity matching.

METHODS

Propensity-matched analysis of a population-based sample of 7971 patients admitted to the medical wards between January 2018 and December 2019 at a single, tertiary United States medical center. The continuous monitoring device measures oxygen saturation, heart rate, respiratory rate, continuous noninvasive blood pressure, and either 3-lead or 5-lead electrocardiogram. Patients received either 12 hours or more of continuous and wireless VS monitoring (n=1450) or intermittent VS monitoring (n=6521). The primary outcome was the odds of a composite of in-hospital mortality or ICU transfer during hospitalization. Secondary outcomes were the odds of individual components of the primary outcome, as well as heart failure (HF), myocardial infarction (MI), acute kidney injury (AKI), and rapid response team (RRT) activations.

RESULTS

Those who received intermittent VS monitoring had greater odds of a composite of in-hospital mortality or ICU admission (odds ratio [OR] 2.79, 95% CI 1.89-4.25; P<.001) compared with those who had continuous and wireless VS monitoring. The odds of HF (OR 1.03, 95% CI 0.83-1.28; P=.77), MI (OR 1.58, 95% CI 0.77-3.47; P=.23), AKI (OR 0.74, 95% CI 0.62-1.02; P=.06), and RRT activation (OR 0.94, 95% CI 0.75-1.19; P=.62) were similar in both groups.

CONCLUSIONS

In this propensity-matched study, medical ward patients who received standard of care intermittent VS monitoring were at nearly 3 times greater odds of transfer to the ICU or death compared with those who received continuous VS monitoring. Our study was primarily limited by the inability to match patients on admission diagnosis due to limitations in electronic health record data. Other limitations included the number of and reasons for false alarms, which can be challenging with continuous monitoring strategies. Given the limitations of this work, these observations need to be confirmed with prospective interventional trials.

Vasoplegic Syndrome in Cardiac Surgery: A Narrative Review of Etiologic Mechanisms and Therapeutic Options

Vasoplegic syndrome, a form of distributive shock that may manifest during or after cardiopulmonary bypass, is a serious complication that increases morbidity and mortality after cardiac surgery. No consensus definition exists, but vasoplegic syndrome is generally described as a state of pathologic vasodilation causing hypotension refractory to fluid resuscitation and vasopressor therapy, and resulting in organ malperfusion despite a normal or increased cardiac output. Diagnosis can be complex as there is a broad differential diagnosis for low systemic vascular resistance in the cardiac surgical patient. Interpretation of hemodynamic data can also be challenging in the setting of mixed shock states and mechanical support. This narrative review summarizes the pathophysiology of vasoplegic syndrome, the literature concerning its incidence and risk factors, the hemodynamic parameters important to the diagnosis of vasoplegic syndrome, a consensus definition of the syndrome, and a proposed goal-directed treatment framework.

Effects of Blood Pressure Management Based on Non-Invasive Heart Function Monitoring on Reducing Postoperative Hypotension in Elderly Patients Undergoing Total Knee Arthroplasty: A Randomized Controlled Trial

BACKGROUND

Postoperative hypotension is a common symptom in elderly patients undergoing total knee arthroplasty (TKA), which is associated with intraoperative blood pressure (BP) management. The study aimed to explore the causes of perioperative hypotension in TKA elderly patients and analyze the effects of BP management strategies based on noninvasive heart function monitoring on reducing postoperative hypotension.

METHODS

A total of 176 elderly TKA patients were divided into four groups: the tourniquet group (group T), the nontourniquet group (group N), the goal-oriented BP management tourniquet group (group GT), and the goal-oriented BP management nontourniquet group (group GN). Patients in groups T and GT received TKA with a tourniquet. The BP of patients in groups GT and GN was maintained based on noninvasive heart function monitoring. The mean arterial pressure (MAP), index of cardiac contractility (ICON), stroke volume (SV), and other circulatory indicators were measured using the noninvasive cardiometer monitor at five time points, including before anesthesia (T1), after anesthesia (T2), after completion of the osteotomy (T3), after suturing (T4), and after leaving the postanesthesia care unit (T5). The frequency of postoperative hypotension within 24 hours was recorded, and the incidence of hypotension was calculated.

RESULTS

The ICON, SV, and MAP were lower in groups N and GN than in groups T and GT at T3 (P < 0.05). The ICON, SV, and MAP were lower in group N than in groups GN at T4 and T5 (P < 0.05), and no significant difference was observed between groups T and GT (P > 0.05). The incidence of postoperative hypotension within 24 hours was higher in group N (47.1%) (P = 0.007) than in group GN (21.6%), group T (19.4%), and group GT (14.8%).

CONCLUSIONS

Postoperative hypotension in elderly patients undergoing TKA with a nontourniquet was associated with decreased myocardial contractility. Enhancing myocardial contractility based on non-invasive cardiac function monitoring reduced the incidence of postoperative hypotension.

Intraoperative hyperthermia is associated with increased acute kidney injury following cytoreductive surgery and hyperthermic intraperitoneal chemotherapy: a retrospective cohort study

BACKGROUND

Acute kidney injury (AKI) is common after cytoreduction surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) for peritoneal surface malignancies. Herein we analyzed the association between intraoperative hyperthermia and AKI following CRS-HIPEC.

METHODS

In this retrospective cohort study, we collected baseline and perioperative data from patients who underwent CRS-HIPEC mainly for pseudomyxoma peritonei between 2014 and 2020. Nasopharyngeal temperature was recorded at 5-min intervals. The area above the threshold was calculated for intraoperative hyperthermia (>37.0 °C). AKI was diagnosed and classified according to the KDIGO creatinine criteria. A multivariable logistic regression model was established to assess the association between hyperthermia and AKI.

RESULTS

A total of 480 patients were included in the analysis. Of these, 10.6% (51/480) developed AKI within 7 postoperative days. After correction for confounding factors, a larger area above the threshold of hyperthermia was significantly associated with an increased risk of AKI (odds ratio [OR] 1.36, 95% CI 1.14-1.63, p = 0.001). Among other factors, older age (OR 1.05, 95% CI 1.02-1.09, p = 0.002), postoperative hypotension requiring vasopressors (OR 2.09, 95% CI 1.02-4.27, p = 0.042), and intraperitoneal chemotherapy containing cisplatin (OR 2.75, 95% CI 1.20-6.33, p = 0.017) were also associated with an increased risk of AKI. Patients with AKI required longer mechanical ventilation, stayed longer in the intensive care unit and hospital, developed more complications, and required more intensive care unit readmission.

CONCLUSIONS

Among patients undergoing CRS-HIPEC, intraoperative hyperthermia was independently associated with a higher risk of AKI; this effect was additive to other risk factors including cisplatin-containing chemotherapy.

An anesthesiology-led perioperative outreach service: experience from a Canadian centre and a focused narrative literature review

Approximately 320 million surgeries occur annually worldwide, increasingly performed on an ageing, comorbid population in whom postoperative complications contribute significantly to mortality. While anesthesiologists have led advances in perioperative care, the optimal structure of the provision of postoperative care has lacked discourse. In this article, we describe the implementation, structure, role, and benefits of an Anesthesiology Perioperative Outreach Service (APOS) at a Canadian tertiary hospital, providing proactive daily review and management of high-risk surgical patients. The APOS involves routine reviews and care on surgical wards, emphasizing collaboration among anesthesiology, internal medicine, surgery, and geriatric medicine teams, with a specific screening pathway to identify patients experiencing myocardial injury after noncardiac surgery. We discuss case vignettes to illustrate common examples of how the APOS enabled early detection and treatment escalation for deteriorating patients and provide a focused narrative literature review. The anesthesiology-led perioperative outreach model described herein could provide an implementable framework for institutions seeking to enhance their quality of postoperative care-particularly among complex, comorbid patients at risk of postoperative morbidity.

Post-anesthesia care unit hypotension in low-risk patients recovering from non-cardiac surgery: a prospective observational study

Intraoperative hypotension is common and associated with organ injury. Hypotension can not only occur during surgery, but also thereafter. After surgery, most patients are treated in post-anesthesia care units (PACU). The incidence of PACU hypotension is largely unknown - presumably in part because arterial pressure is usually monitored intermittently in PACU patients. We therefore aimed to evaluate the incidence, duration, and severity of PACU hypotension in low-risk patients recovering from non-cardiac surgery. In this observational study, we performed blinded continuous non-invasive arterial pressure monitoring with finger-cuffs (ClearSight system; Edwards Lifesciences, Irvine, CA, USA) in 100 patients recovering from non-cardiac surgery in the PACU. We defined PACU hypotension as a mean arterial pressure (MAP) < 65 mmHg. Patients had continuous finger-cuff monitoring for a median (25th percentile, 75th percentile) of 64 (44 to 91) minutes. Only three patients (3%) had PACU hypotension for at least one consecutive minute. These three patients had 4, 4, and 2 cumulative minutes of PACU hypotension; areas under a MAP of 65 mmHg of 17, 9, and 9 mmHg x minute; and time-weighted averages MAP less than 65 mmHg of 0.5, 0.3, and 0.2 mmHg. The median volume of crystalloid fluid patients were given during PACU treatment was 200 (100 to 400) ml. None was given colloids or a vasopressor during PACU treatment. In low-risk patients recovering from non-cardiac surgery, the incidence of PACU hypotension was very low and the few episodes of PACU hypotension were short and of modest severity.

Intraoperative hypotension is associated with decreased long-term survival in older patients after major noncardiac surgery: Secondary analysis of three randomized trials

STUDY OBJECTIVE

To assess the association of intraoperative hypotension with long-term survivals in older patients after major noncardiac surgery mainly for cancer.

DESIGN

A secondary analysis of databases from three randomized trials with long-term follow-up.

SETTING

The underlying trials were conducted in 17 tertiary hospitals in China.

PATIENTS

Patients aged 60 to 90 years who underwent major noncardiac thoracic or abdominal surgeries (≥ 2 h) in a single center were included in this analysis.

EXPOSURES

Restricted cubic spline models were employed to determine the lowest mean arterial pressure (MAP) threshold that was potentially harmful for long-term survivals. Patients were arbitrarily divided into three groups according to the cumulative duration or area under the MAP threshold. The association between intraoperative hypotension exposure and long-term survivals were analyzed with the Cox proportional hazard regression models.

MEASUREMENTS

Our primary endpoint was overall survival. Secondary endpoints included recurrence-free and event-free survivals.

MAIN RESULTS

A total of 2664 patients (mean age 69.0 years, 34.9% female sex, 92.5% cancer surgery) were included in the final analysis. MAP < 60 mmHg was adopted as the threshold of intraoperative hypotension. Patients were divided into three groups according to duration under MAP < 60 mmHg (<1 min, 1-10 min, and > 10 min) or area under MAP <60 mmHg (< 1 mmHg⋅min, 1-30 mmHg⋅min, and > 30 mmHg⋅min). After adjusting confounders, duration under MAP < 60 mmHg for > 10 min was associated with a shortened overall survival when compared with the < 1 min patients (adjusted hazard ratio [HR] 1.31, 95% confidence interval [CI] 1.09 to 1.57, P = 0.004); area under MAP < 60 mmHg for > 30 mmHg⋅min was associated with a shortened overall survival when compared with the < 1 mmHg⋅min patients (adjusted HR 1.40, 95% CI 1.16 to 1.68, P < 0.001). Similar associations exist between duration under MAP < 60 mmHg for > 10 min or area under MAP < 60 mmHg for > 30 mmHg⋅min and recurrence-free or event-free survivals.

CONCLUSIONS

In older patients who underwent major noncardiac surgery mainly for cancer, intraoperative hypotension was associated with worse overall, recurrence-free, and event-free survivals.

Association of velocity-pressure loop-derived values recorded during neurosurgical procedures with postoperative organ failure biomarkers: a retrospective single-center study

BACKGROUND

Perioperative renal and myocardial protection primarily depends on preoperative prediction tools, along with intraoperative optimization of cardiac output (CO) and mean arterial pressure (MAP). We hypothesise that monitoring the intraoperative global afterload angle (GALA), a proxy of ventricular afterload derived from the velocity pressure (VP) loop, could better predict changes in postoperative biomarkers than the recommended traditional MAP and CO.

METHOD

This retrospective monocentric study included patients programmed for neurosurgery with continuous VP loop monitoring. Patients with hemodynamic instability were excluded. Those presenting a 1-day post-surgery increase in creatinine, B-type natriuretic peptide, or troponin Ic us were labelled Bio+, Bio- otherwise. Demographics, intra-operative data, and comorbidities were considered as covariates. The study aimed to determine if intraoperative GALA monitoring could predict early postoperative biomarker disruption.

RESULT

From November 2018 to November 2020, 86 patients were analysed (Bio+/Bio- = 47/39). Bio+ patients were significantly older (62 [54-69] vs. 42 [34-57] years, p <  0.0001), More often hypertensive (25% vs. 9%, p = 0.009), and more frequently treated with antihypertensive drugs (31.9% vs. 7.7%, p = 0.013). GALA was significantly larger in Bio+ patients (40 [31-56] vs. 23 [19-29] °, p < 0.0001), while CO, MAP, and cumulative time spent <65mmHg were similar between groups. GALA exhibited strong predictive performances for postoperative biological deterioration (AUC = 0.88 [0.80-0.95]), significantly outperforming MAP (MAP AUC = 0.55 [0.43-0.68], p < 0.0001).

CONCLUSION

GALA under general anaesthesia prove more effective in detecting patients at risk of early cardiac or renal biological deterioration, compared to classical hemodynamic parameters.

Outcomes and complications of hemodialysis in patients with renal cancer following bilateral nephrectomy

Objectives

The management of patients undergoing bilateral nephrectomy for renal cancer presents significant challenges, particularly in addressing hypotension, anemia, and tumor recurrence during hemodialysis.

Case presentation

A patient diagnosed with renal clear cell carcinoma in 2009 was followed until his demise in June 2022, with detailed documentation of symptoms, signs, laboratory results, diagnosis, and treatment. In the presented case, post-nephrectomy, the patient experienced frequent hypotension and anemia during dialysis, improving with erythropoietin-stimulating agents and subsequently with rosuvastatin. Later, multiple metastases were detected, correlating with normalized blood pressure and hemoglobin.

Literature review

A literature search up to September 2023 was also conducted, gathering data on hypotension, anemia, and tumor recurrence post-nephrectomy. Literature analysis of six cases revealed a 100% tumor recurrence rate in elderly patients (>50 years).

Conclusion

Treatment of anemia in bilateral nephrectomy patients warrants consideration of medication-induced tumor recurrence, highlighting early kidney transplantation to avoid adverse reactions like hypotension.

PeriOperative Quality Initiative (POQI) international consensus statement on perioperative arterial pressure management

Arterial pressure monitoring and management are mainstays of haemodynamic therapy in patients having surgery. This article presents updated consensus statements and recommendations on perioperative arterial pressure management developed during the 11th POQI PeriOperative Quality Initiative (POQI) consensus conference held in London, UK, on June 4-6, 2023, which included a diverse group of international experts. Based on a modified Delphi approach, we recommend keeping intraoperative mean arterial pressure ≥60 mm Hg in at-risk patients. We further recommend increasing mean arterial pressure targets when venous or compartment pressures are elevated and treating hypotension based on presumed underlying causes. When intraoperative hypertension is treated, we recommend doing so carefully to avoid hypotension. Clinicians should consider continuous intraoperative arterial pressure monitoring as it can help reduce the severity and duration of hypotension compared to intermittent arterial pressure monitoring. Postoperative hypotension is often unrecognised and might be more important than intraoperative hypotension because it is often prolonged and untreated. Future research should focus on identifying patient-specific and organ-specific hypotension harm thresholds and optimal treatment strategies for intraoperative hypotension including choice of vasopressors. Research is also needed to guide monitoring and management strategies for recognising, preventing, and treating postoperative hypotension.

Effectiveness and safety of enhanced postoperative care units for non-cardiac, non-neurological surgery: a systematic review protocol

OBJECTIVE

The proposed systematic review will evaluate the evidence on the effectiveness and safety of enhanced post-operative care (EPC) units on patient and health service outcomes in adult patients following non-cardiac, non-neurological surgery.

INTRODUCTION

The increase in surgical procedures globally has placed a significant economic and societal burden on health care systems. Recognizing this challenge, EPC units have emerged as a model of care, bridging the gap between traditional, ward-level care and intensive care. EPC offers benefits such as higher staff-to-patient ratios, close patient monitoring (eg, invasive monitoring), and access to critical interventions (eg, vasopressor support). However, there is a lack of well-established guidelines and empirical evidence regarding the safety and effectiveness of EPC units for adult patients following surgery.

INCLUSION CRITERIA

This review will include studies involving adult patients (≥18 years) undergoing any elective or emergency non-cardiac, non-neurological surgery, who have been admitted to an EPC unit. Experimental, quasi-experimental, and observational study designs will be eligible.

METHODS

This review will follow the JBI methodology for systematic reviews of effectiveness. The search strategy will identify published and unpublished studies from the Cochrane Library, MEDLINE (Ovid), Embase (Ovid), and Scopus, as well as gray literature sources, from 2010 to the present. Two independent reviewers will screen studies, extract data, and critically appraise selected studies using standardized JBI assessment tools. Where feasible, a statistical meta-analysis will be performed to combine study findings. The certainty of evidence will be assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology.

REVIEW REGISTRATION

PROSPERO CRD42023455269.

An audit of postoperative haemodynamic stability after intraoperative labetalol administration in non-cardiac surgery patients

Anaesthesiologists commonly use intravenous labetalol to adjust patient haemodynamics during surgical procedures. Cases of profound hypotension after continuous labetalol infusions have been reported; however, there is limited evidence regarding the safety of intraoperative labetalol boluses. This audit examined the frequency of postoperative hypotension and bradycardia in 292 adult non-cardiac surgery patients treated with intraoperative labetalol boluses. Blood pressure and heart rate data were collected from the post-anaesthesia care unit and on the floor units for 24 hours after surgery. The median total intraoperative labetalol dose was 10mg. A total of 30/292 patients had all-cause postoperative hypotension within 24 hours of surgery, 26 of which had other medical or surgical precipitants. Fifteen patients developed bradycardia. There were no deaths or intensive care unit admissions attributed to labetalol. This audit demonstrates a low risk of all-cause postoperative hypotension (10%) and bradycardia (5%) after the use of small IV doses of intraoperative labetalol.

Effect of remimazolam versus propofol anesthesia on postoperative delirium in neurovascular surgery: study protocol for a randomized controlled, non-inferiority trial

BACKGROUND

Remimazolam is a short-acting benzodiazepine newly approved for the induction and maintenance of general anesthesia. Remimazolam emerges as an ideal drug for the neurosurgical population due to its rapid emergence, enabling early neurological assessment, and its ability to maintain perfusion pressure, which is crucial for preventing cerebral ischemia. However, the use of benzodiazepine has been associated with an increased risk of postoperative delirium (POD). There is currently limited evidence about the relationship between remimazolam-based total intravenous anesthesia (TIVA) and POD.

METHODS

In this double-blind, randomized, non-inferiority trial, we plan to include 696 adult patients with American Society of Anesthesiologists physical status class I to III, undergoing elective neurovascular surgery under general anesthesia. After informed consent, the patients will be randomized to receive either remimazolam or propofol-based TIVA with a 1:1 ratio. The primary outcome is the incidence of POD within 5 days after surgery. Secondary outcomes include subtypes, number of positive assessments and severity of POD, emergence agitation, intraoperative awareness and undesirable patient movement, intraoperative hypotension, and postoperative cognitive function. The data will be analyzed in modified intention to treat.

DISCUSSION

This trial will evaluate the effect of remimazolam on the development of POD compared to propofol anesthesia. The results of this trial will provide evidence regarding the choice of optimal anesthetics to minimize the risk of POD in neurosurgical patients.

TRIAL REGISTRATION

The study protocol was prospectively registered at the Clinical trials ( https://clinicaltrials.gov , NCT06115031, principal investigator: Jiseon Jeong; date of first registration: November 2, 2023, before the recruitment of the first participant.

Pathophysiological mechanisms underlying increased circulating cardiac troponin in noncardiac surgery: a narrative review

Assay-specific increases in circulating cardiac troponin are observed in 20-40% of patients after noncardiac surgery, depending on patient age, type of surgery, and comorbidities. Increased cardiac troponin is consistently associated with excess morbidity and mortality after noncardiac surgery. Despite these findings, the underlying mechanisms are unclear. The majority of interventional trials have been designed on the premise that ischaemic cardiac disease drives elevated perioperative cardiac troponin concentrations. We consider data showing that elevated circulating cardiac troponin after surgery could be a nonspecific marker of cardiomyocyte stress. Elevated concentrations of circulating cardiac troponin could reflect coordinated pathological processes underpinning organ injury that are not necessarily caused by ischaemia. Laboratory studies suggest that matching of coronary artery autoregulation and myocardial perfusion-contraction coupling limit the impact of systemic haemodynamic changes in the myocardium, and that type 2 ischaemia might not be the likeliest explanation for cardiac troponin elevation in noncardiac surgery. The perioperative period triggers multiple pathological mechanisms that might cause cardiac troponin to cross the sarcolemma. A two-hit model involving two or more triggers including systemic inflammation, haemodynamic strain, adrenergic stress, and autonomic dysfunction might exacerbate or initiate acute myocardial injury directly in the absence of cell death. Consideration of these diverse mechanisms is pivotal for the design and interpretation of interventional perioperative trials.

Impact of continuous and wireless monitoring of vital signs on clinical outcomes: a propensity-matched observational study of surgical ward patients

BACKGROUND

Continuous and wireless vital sign monitoring is superior to intermittent monitoring in detecting vital sign abnormalities; however, the impact on clinical outcomes has not been established.

METHODS

We performed a propensity-matched analysis of data describing patients admitted to general surgical wards between January 2018 and December 2019 at a single, tertiary medical centre in the USA. The primary outcome was a composite of in-hospital mortality or ICU transfer during hospitalisation. Secondary outcomes were the odds of individual components of the primary outcome, and heart failure, myocardial infarction, acute kidney injury, and rapid response team activations. Data are presented as odds ratios (ORs) with 95% confidence intervals (CIs) and n (%).

RESULTS

We initially screened a population of 34,636 patients (mean age 58.3 (Range 18-101) yr, 16,456 (47.5%) women. After propensity matching, intermittent monitoring (n=12 345) was associated with increased risk of a composite of mortality or ICU admission (OR 3.42, 95% CI 3.19-3.67; P<0.001), and heart failure (OR 1.48, 95% CI 1.21-1.81; P<0.001), myocardial infarction (OR 3.87, 95% CI 2.71-5.71; P<0.001), and acute kidney injury (OR 1.32, 95% CI 1.09-1.57; P<0.001) compared with continuous wireless monitoring (n=7955). The odds of rapid response team intervention were similar in both groups (OR 0.86, 95% CI 0.79-1.06; P=0.726).

CONCLUSIONS

Patients who received continuous ward monitoring were less likely to die or be admitted to ICU than those who received intermittent monitoring. These findings should be confirmed in prospective randomised trials.

Introduction of a Post-Anaesthesia Care Unit in a Teaching Hospital Is Associated with a Reduced Length of Hospital Stay in Noncardiac Surgery: A Single-Centre Interrupted Time Series Analysis

BACKGROUND

A post-anaesthesia care unit (PACU) may improve postoperative care compared with intermediate care units (IMCU) due to its dedication to operative care and an individualized duration of postoperative stay. The effects of transition from IMCU to PACU for postoperative care following intermediate to high-risk noncardiac surgery on length of hospital stay, intensive care unit (ICU) utilization, and postoperative complications were investigated.

METHODS

This single-centre interrupted time series analysis included patients undergoing eleven different noncardiac surgical procedures associated with frequent postoperative admissions to an IMCU or PACU between January 2018 and March 2019 (IMCU episode) and between October 2019 and December 2020 (PACU episode). Primary outcome was hospital length of stay, secondary outcomes included postoperative complications and ICU admissions.

RESULTS

In total, 3300 patients were included. The hospital length of stay was lower following PACU admission compared to IMCU admission (IMCU 7.2 days [4.2-12.0] vs. PACU 6.0 days [3.6-9.1]; p < 0.001). Segmented regression analysis demonstrated that the introduction of the PACU was associated with a decrease in hospital length of stay (GMR 0.77 [95% CI 0.66-0.91]; p = 0.002). No differences between episodes were detected in the number of postoperative complications or postoperative ICU admissions.

CONCLUSIONS

The introduction of a PACU for postoperative care of patients undergoing intermediate to high-risk noncardiac surgery was associated with a reduction in the length of stay at the hospital, without increasing postoperative complications.

Postoperative arterial hypotension: the unnoticed enemy

Postoperative hypotension is a frequently underestimated health problem associated with high morbidity and mortality and increased use of health care resources. It also poses significant clinical, technological, and human challenges for healthcare. As it is a modifiable and avoidable risk factor, this document aims to increase its visibility, defining its clinical impact and the technological challenges involved in optimizing its management, taking clinical-technological, humanistic, and economic aspects into account.

Implementing screening for myocardial injury in non-cardiac surgery: perspectives of an ad-hoc interdisciplinary expert group

Objectives. Perioperative myocardial injury (PMI) is increasingly recognised as an important complication of non-cardiac surgery, with often clinically silent presentation, but detrimental prognosis. Active screening for PMI, involving the detection of dynamic and elevated levels of cardiac troponin, has recently been advocated by an increasing number of guidelines; however, active PMI screening has not been reflected in clinical practice. Design. As consensus on a common screening and management pathway is lacking, we synthesise the current evidence to provide suggestions on the selection of patients for screening, organisation of a screening program, and a potential management pathway, building upon a recently published perioperative screening algorithm. Results. Screening should be performed using high-sensitivity assays both preoperatively and postoperatively (postoperative Days 1 and 2) in patients at high-risk of experiencing perioperative complications. Conclusion. This expert opinion piece by an interdisciplinary group of predominantly Norwegian clinicians aims to assist healthcare professionals planning to implement guideline-recommended PMI screening at a local level in order to improve patient outcomes following non-cardiac surgery.

Association between postoperative hypotension and acute kidney injury after noncardiac surgery: a historical cohort analysis

PURPOSE

The extent to which postoperative hypotension contributes to renal injury remains unclear, much less what the harm thresholds might be. We therefore tested the primary hypothesis that there is an absolute hypotensive arterial pressure threshold for acute kidney injury during the initial seven days after noncardiac surgery.

METHODS

We conducted a single-centre historical cohort analysis of adults who had noncardiac surgery and had creatinine recorded preoperatively and postoperatively. Our exposure was the lowest postoperative mean arterial pressure, defined as the average of the three lowest postoperative pressure measurements. Our primary analysis was the association between the lowest mean arterial pressure and acute kidney injury, defined according to Kidney Disease: Improving Global Outcomes initiative criteria. Our analysis was adjusted for potentially relevant confounding factors including intraoperative hypotension.

RESULTS

Among 64,349 patients analyzed, 2,812 (4.4%) patients had postoperative acute kidney injury. Each 5-mm Hg decrease in the lowest mean arterial pressure was associated with a 28% (97.5% confidence interval [CI], 23 to 32; P < 0.001) increase in the odds of acute kidney injury for lowest mean arterial pressures < 80 mm Hg. Higher lowest pressures were not associated with acute kidney injury (odds ratio, 1.08; 97.5% CI, 0.99 to 1.17; P = 0.04) for each 5-mm Hg decrease in the lowest mean arterial pressure.

CONCLUSION

Postoperative hypotension, defined as the lowest postoperative mean arterial pressure < 80 mm Hg, was associated with acute kidney injury after noncardiac surgery. A prospective trial will be required to determine whether the observed association is causal and thus amenable to modification.

Tight perioperative blood pressure management to reduce complications: a randomised feasibility trial

OBJECTIVE

Evaluate the feasibility of a trial of perioperative hypotension and serious complications.

DESIGN

A patient and assessor-blinded randomised feasibility trial.

SETTING

We included patients in a tertiary university hospital.

PARTICIPANTS

We enrolled 80 adults scheduled for major non-cardiac surgery.

INTERVENTIONS

In patients randomised to tight blood pressure control, intraoperative mean arterial pressure (MAP) was targeted to ≥85 mm Hg maintained with norepinephrine infusion, and restarting chronic antihypertensive medications was delayed until the third postoperative day. In the reference group, intraoperative blood pressure was managed per routine and antihypertensive medications were restarted immediately after surgery.

PRIMARY AND SECONDARY OUTCOME MEASURES

Our first co-primary outcome was the fraction of time when intraoperative MAP was >85 mm Hg, intraoperative area (time integral) of MAP >85 mm Hg and MAP <65 mm Hg. The second co-primary outcome was time until antihypertensive medications were restarted after surgery. Secondary outcomes were time-weighted average intraoperative MAP, cumulative minimum MAP for 10 min, average postoperative systolic blood pressure (SBP) and mean of the lowest three postoperative SBPs.

RESULTS

Forty patients in each group were analysed. The median for intraoperative area of MAP >85 mm Hg was 1303 (772-2419) mm Hg*min in routine blood pressure (BP) cases and 2425 (1926-3545) mm Hg*min in tight BP control. The area for intraoperative MAP <65 mm Hg was 7 (0-40) mm Hg*min with routine BP management, and 0 (0-0) mm Hg*min with tight BP control. The fraction of time with MAP >85 mm Hg was 0.52 (0.25) and 0.87 (0.15). Antihypertensive medications were restarted 2 (1-3) days later in tight BP control cases. However, postoperative SBPs were similar.

CONCLUSIONS

Tight BP management markedly increased intraoperative MAP and reduced the amount of hypotension. In contrast, delaying chronic antihypertensive medications had little effect on postoperative SBP. The full trial appears feasible and remains necessary but should not include postoperative antihypertensive management.

TRIAL REGISTRATION

NCT04789733.

Vasopressors to treat postoperative hypotension after adult noncardiac, non-obstetric surgery: a systematic review

BACKGROUND

Postoperative hypotension is common after major surgery and is associated with patient harm. Vasopressors are commonly used to treat hypotension without clear evidence of benefit. We conducted a systematic review to better understand the use, impact, and rationale for vasopressor administration after noncardiac, non-obstetric surgery in adults.

METHODS

We conducted a prospectively registered systematic review. Cochrane CENTRAL, EMBASE, MEDBASE, and MEDLINE were searched for RCTs and cohort studies of adult patients receiving vasopressors after noncardiac, non-obstetric surgery. Study quality was critically appraised by two investigators. Findings from the review were synthesised, but formal meta-analysis was not performed because of significant variability in study populations and outcomes.

RESULTS

A total of 3201 articles were screened, of which seven RCTs, two prospective cohort studies, and 15 retrospective cohort studies were included in the analysis (24 in total). One study was graded as high quality, two as moderate quality, and the remaining 21 as low quality. Sixteen studies relied on clinical assessment alone to decide on therapeutic interventions. Vasodilation was the most common suggested physiological disturbance. The median proportion of patients receiving vasopressors was 42% (interquartile range: 11.5-74.7%). Norepinephrine was the most common vasopressor used.

CONCLUSIONS

The evidence supporting the use of vasopressors to treat postoperative hypotension is limited. Future research should focus on whether vasodilatation or other physiological disturbance is driving postoperative hypotension to allow rational decision-making.

Incidence, severity and detection of blood pressure and heart rate perturbations in postoperative ward patients after noncardiac surgery

STUDY OBJECTIVE

We sought to determine changes in continuous mean and systolic blood pressure and heart rate in a cohort of non-cardiac surgical patients recovering on the postoperative ward. Furthermore, we estimated the proportion of vital signs changes that would remain undetected with intermittent vital signs checks.

DESIGN

Retrospective cohort.

SETTING

Post-operative general ward.

PATIENTS

14,623 adults recovering from non-cardiac surgical procedures.

INTERVENTIONS & MEASUREMENTS

Using a wireless, noninvasive monitor, we recorded postoperative blood pressure and heart rate at 15-s intervals and encouraged nursing intervention as clinically indicated.

MAIN RESULTS

7% of our cohort of 14,623 patients spent >15 sustained minutes with a MAP <65 mmHg, and 23% had MAP <75 mmHg for 15 sustained minutes. Hypertension was more common, with 67% of patients spending at least 60 sustained minutes with MAP >110 mmHg. Systolic pressures <90 mmHg were present for 15 sustained minutes in about a fifth of all patients, and 40% of patients had pressures >160 mmHg sustained for 30 min. 40% of patients were tachycardic with heart rates >100 beats/min for at least continuous 15 min and 15% of patients were bradycardic at a threshold of <50 beats/min for 5 sustained minutes. Conventional vital sign assessments at 4-h intervals would have missed 54% of mean pressure episodes <65 mmHg sustained >15 min, 20% of episodes of mean pressures >130 mmHg sustained >30 min, 36% of episodes of heart rate > 120 beats/min sustained <10 min, and 68% of episodes of heart rate sustained <40 beats per minute for >3 min.

CONCLUSIONS

Substantial hemodynamic disturbances persisted despite implementing continuous portable ward monitoring coupled with nursing alarms and interventions. A significant proportion of these changes would have gone undetected using traditional intermittent monitoring. Better understanding of effective responses to alarms and appropriate interventions on hospital wards remains necessary.

Intraoperative hypotension in noncardiac surgery patients with chronic beta-blocker therapy: A matched cohort analysis

STUDY OBJECTIVE

To explore the incidence of intraoperative hypotension in patients with chronic beta-blocker therapy, expressed as time spent, area and time-weighted average under predefined mean arterial pressure thresholds.

DESIGN

Retrospective analysis of a prospective observational cohort registry.

SETTING

Patients ≥60 years undergoing intermediate- to high-risk noncardiac surgery with routine postoperative troponin measurements on the first three days after surgery.

PATIENTS

1468 matched sets of patients (1:1 ratio with replacement) with and without chronic beta-blocker treatment.

INTERVENTIONS

None.

MEASUREMENTS

The primary outcome was the exposure to intraoperative hypotension in beta-blocker users vs. non-users. Time spent, area and time-weighted average under predefined mean arterial pressure thresholds (55-75 mmHg) were calculated to express the duration and severity of exposure. Secondary outcomes included incidence of postoperative myocardial injury and thirty-day mortality, myocardial infarction (MI) and stroke. Furthermore, analyses for patient subgroup and beta-blocker subtype were conducted.

MAIN RESULTS

In patients with chronic beta-blocker therapy, no increased exposure to intraoperative hypotension was observed for all characteristics and thresholds calculated (all P > .05). Beta-blocker users had lower heart rate before, during and after surgery (70 vs. 74, 61 vs. 65 and 68 vs. 74 bpm, all P < .001, respectively). Postoperative myocardial injury (13.6% vs. 11.6%, P = .269) and thirty-day mortality (2.5% vs. 1.4%, P = .055), MI (1.4% vs. 1.5%, P = .944) and stroke (1.0% vs 0.7%, P =  .474) rates were comparable. The results were consistent in subtype and subgroup analyses.

CONCLUSIONS

In this matched cohort analysis, chronic beta-blocker therapy was not associated with increased exposure to intraoperative hypotension in patients undergoing intermediate- to high-risk noncardiac surgery. Furthermore, differences in patient subgroups and postoperative adverse cardiovascular events as a function of treatment regimen could not be demonstrated.

Persistent postoperative hypotension caused by subclinical empty sella syndrome after a simple surgery: A case report

BACKGROUND

Empty sella is an anatomical and radiological finding of the herniation of the subarachnoid space into the pituitary fossa leading to a flattened pituitary gland. Patients with empty sella may present with various symptoms, including headache due to intracranial hypertension and endocrine symptoms related to the specific pituitary hormones affected. Here, we report a female patient who developed persistent postoperative hypotension caused by subclinical empty sella syndrome after a simple surgery.

CASE SUMMARY

A 47-year-old woman underwent vocal cord polypectomy under general anesthesia with endotracheal intubation. She denied any medical history, and her vital signs were normal before the surgery. Anesthesia and surgery were uneventful. However, she developed dizziness, headache and persistent hypotension in the ward. Thus, intravenous dopamine was started to maintain normal blood pressure, which improved her symptoms. However, she remained dependent on dopamine for over 24 h without any obvious anesthesia- and surgery-related complications. An endocrine etiology was then suspected, and further examination showed a high prolactin level, a low normal adrenocorticotropic hormone level and a low cortisol level. Magnetic resonance imaging of the brain revealed an empty sella. Therefore, she was diagnosed with empty sella syndrome and secondary adrenal insufficiency. Her symptoms disappeared one week later after daily glucocorticoid supplement.

CONCLUSION

Endocrine etiologies such as pituitary and adrenal-related dysfunction should be considered in patients showing persistent postoperative hypotension when anesthesia- and surgery-related factors are excluded.

Continuous Blood Pressure Monitoring in Patients Having Surgery: A Narrative Review

Hypotension can occur before, during, and after surgery and is associated with postoperative complications. Anesthesiologists should thus avoid profound and prolonged hypotension. A crucial part of avoiding hypotension is accurate and tight blood pressure monitoring. In this narrative review, we briefly describe methods for continuous blood pressure monitoring, discuss current evidence for continuous blood pressure monitoring in patients having surgery to reduce perioperative hypotension, and expand on future directions and innovations in this field. In summary, continuous blood pressure monitoring with arterial catheters or noninvasive sensors enables clinicians to detect and treat hypotension immediately. Furthermore, advanced hemodynamic monitoring technologies and artificial intelligence-in combination with continuous blood pressure monitoring-may help clinicians identify underlying causes of hypotension or even predict hypotension before it occurs.

Perioperative individualized hemodynamic optimization according to baseline mean arterial pressure in cardiac surgery patients: Rationale and design of the OPTIPAM randomized trial

BACKGROUND

Postoperative morbidity and mortality after cardiac surgery with cardiopulmonary bypass (CPB) remain high despite recent advances in both anesthesia and perioperative management. Among modifiable risk factors for postoperative complications, optimal arterial pressure during and after surgery has been under debate for years. Recent data suggest that optimizing arterial pressure to the baseline of the patient may improve outcomes. We hypothesize that optimizing the mean arterial pressure (MAP) to the baseline MAP of the patient during cardiac surgery with CPB and during the first 24 hours postoperatively may improve outcomes.

STUDY DESIGN

The OPTIPAM trial (NCT05403697) will be a multicenter, randomized, open-label controlled trial testing the superiority of optimized MAP management as compared with a MAP of 65 mm Hg or more during both the intraoperative and postoperative periods in 1,100 patients scheduled for cardiac surgery with CPB. The primary composite end point is the occurrence of acute kidney injury, neurological complications including stroke or postoperative delirium, and death. The secondary end points are hospital and intensive care unit lengths of stay, Day 7 and Day 90 mortality, postoperative cognitive dysfunction on Day 7 and Day 90, and quality of life at Day 7 and Day 90. Two interim analyses will assess the safety of the intervention.

CONCLUSION

The OPTIPAM trial will assess the effectiveness of an individualized target of mean arterial pressure in cardiac surgery with CPB in reducing postoperative morbidity.

CLINICAL TRIAL REGISTRATION

NCT05403697.

Hypotension-Avoidance Versus Hypertension-Avoidance Strategies in Noncardiac Surgery : An International Randomized Controlled Trial

BACKGROUND

Among patients having noncardiac surgery, perioperative hemodynamic abnormalities are associated with vascular complications. Uncertainty remains about what intraoperative blood pressure to target and how to manage long-term antihypertensive medications perioperatively.

OBJECTIVE

To compare the effects of a hypotension-avoidance and a hypertension-avoidance strategy on major vascular complications after noncardiac surgery.

DESIGN

Partial factorial randomized trial of 2 perioperative blood pressure management strategies (reported here) and tranexamic acid versus placebo. (ClinicalTrials.gov: NCT03505723).

SETTING

110 hospitals in 22 countries.

PATIENTS

7490 patients having noncardiac surgery who were at risk for vascular complications and were receiving 1 or more long-term antihypertensive medications.

INTERVENTION

In the hypotension-avoidance strategy group, the intraoperative mean arterial pressure target was 80 mm Hg or greater; before and for 2 days after surgery, renin-angiotensin-aldosterone system inhibitors were withheld and the other long-term antihypertensive medications were administered only for systolic blood pressures 130 mm Hg or greater, following an algorithm. In the hypertension-avoidance strategy group, the intraoperative mean arterial pressure target was 60 mm Hg or greater; all antihypertensive medications were continued before and after surgery.

MEASUREMENTS

The primary outcome was a composite of vascular death and nonfatal myocardial injury after noncardiac surgery, stroke, and cardiac arrest at 30 days. Outcome adjudicators were masked to treatment assignment.

RESULTS

The primary outcome occurred in 520 of 3742 patients (13.9%) in the hypotension-avoidance group and in 524 of 3748 patients (14.0%) in the hypertension-avoidance group (hazard ratio, 0.99 [95% CI, 0.88 to 1.12]; P = 0.92). Results were consistent for patients who used 1 or more than 1 antihypertensive medication in the long term.

LIMITATION

Adherence to the assigned strategies was suboptimal; however, results were consistent across different adherence levels.

CONCLUSION

In patients having noncardiac surgery, our hypotension-avoidance and hypertension-avoidance strategies resulted in a similar incidence of major vascular complications.

PRIMARY FUNDING SOURCE

Canadian Institutes of Health Research, National Health and Medical Research Council (Australia), and Research Grant Council of Hong Kong.

Defining a postoperative mean arterial pressure threshold in association with acute kidney injury after cardiac surgery: a prospective observational study

Acute kidney injury (AKI) is a common but fatal complication after cardiac surgery. In the absence of effective treatments, the identification and modification of risk factors has been a major component of disease management. However, the optimal blood pressure target for preventing cardiac surgery-associated acute kidney injury (CSA-AKI) remains unclear. We sought to determine the effect of postoperative mean arterial pressure (MAP) in CSA-AKI. It is hypothesized that longer periods of hypotension after cardiac surgery are associated with an increased risk of AKI. This prospective cohort study was conducted on adult patients who underwent cardiac surgery requiring cardiopulmonary bypass at a tertiary center between October 2018 and May 2020. The primary outcome is the occurrence of CSA-AKI. MAP and its duration in the ranges of less than 65, 65 to 74, and 75 to 84 mmHg within 24 h after surgery were recorded. The association between postoperative MAP and CSA-AKI was examined by using logistic regression. Among the 353 patients enrolled, 217 (61.5%) had a confirmed diagnosis of CSA-AKI. Each 1 h epoch of postoperative MAP less than 65 mmHg was associated with an adjusted odds ratio of 1.208 (95% CI, 1.007 to 1.449; P = 0.042), and each 1 h epoch of postoperative MAP between 65 and 74 mmHg was associated with an adjusted odds ratio of 1.144 (95% CI, 1.026 to 1.275; P = 0.016) for CSA-AKI. A potentially modifiable risk factor, postoperative MAP less than 75 mmHg for 1 h or more is associated with an increased risk of CSA-AKI.

Associations between intraoperative hypotension, duration of surgery and postoperative myocardial injury after noncardiac surgery: a retrospective single-centre cohort study

BACKGROUND

Studies of intraoperative hypotension typically specify a blood pressure threshold associated with adverse outcomes. Such thresholds are likely to be study-biased, investigator-biased, or both. We hypothesised that a newly developed modelling method without a threshold, which is biologically more plausible than a threshold-based approach, would reveal a continuous association between exposure to intraoperative hypotension and adverse outcomes.

METHODS

Single-centre, retrospective cohort study of subjects ≥60 yr old undergoing noncardiac surgery. We modelled intraoperative hypotension using three different approaches: (1) unweighted, (2) weighted for degree of hypotension (depth), and (3) weighted for duration of hypotension. The primary outcome was myocardial injury, defined as elevated troponin I (>60 ng L^-1) measured during the first 3 days after surgery. The associations between the three models, postoperative myocardial injury, and mortality (secondary outcome) were reported as penalised adjusted odds ratios (ORs) scaled between the 75th and 25th percentiles.

RESULTS

Myocardial injury occurred in 1812/15 452 (12%) procedures, with 554/15 452 (3.6%) procedures resulting in death before discharge from hospital. The unweighted lower blood pressure measure (OR: 0.26, 95% confidence interval [CI]: 0.12-0.53) and the depth-weighted measure (OR: 4.4, 95% CI: 2.6-7.4) were associated with myocardial injury. The duration-weighted measure was not associated with myocardial injury (OR: 0.89, 95% CI: 0.61-1.3). The unweighted measure (OR 0.08, 95% CI: 0.01-0.40) and the depth-weighted measure (OR: 12, 95% CI, 3.8-35) were associated with in-hospital mortality, but not the duration-weighted measure (OR: 1.3, 95% CI: 0.53-3.0).

CONCLUSIONS

Intraoperative hypotension appears to have a graded association with postoperative myocardial injury and mortality, with depth appearing to contribute more than duration.

Ventilatory efficiency is superior to peak oxygen uptake for prediction of lung resection cardiovascular complications

Introduction

Ventilatory efficiency (V_E/VCO₂ slope) has been shown superior to peak oxygen consumption (VO₂) for prediction of post-operative pulmonary complications in patients undergoing thoracotomy. V_E/VCO₂ slope is determined by ventilatory drive and ventilation/perfusion mismatch whereas VO₂ is related to cardiac output and arteriovenous oxygen difference. We hypothesized pre-operative VO₂ predicts post-operative cardiovascular complications in patients undergoing lung resection.

Methods

Lung resection candidates from a published study were evaluated by post-hoc analysis. All of the patients underwent preoperative cardiopulmonary exercise testing. Post-operative cardiovascular complications were assessed during the first 30 post-operative days or hospital stay. One-way analysis of variance or the Kruskal–Wallis test, and multivariate logistic regression were used for statistical analysis and data summarized as median (IQR).

Results

Of 353 subjects, 30 (9%) developed pulmonary complications only (excluded from further analysis), while 78 subjects (22%) developed cardiovascular complications and were divided into two groups for analysis: cardiovascular only (n = 49) and cardiovascular with pulmonary complications (n = 29). Compared to patients without complications (n = 245), peak VO₂ was significantly lower in the cardiovascular with pulmonary complications group [19.9 ml/kg/min (16.5–25) vs. 16.3 ml/kg/min (15–20.3); P<0.01] but not in the cardiovascular only complications group [19.9 ml/kg/min (16.5–25) vs 19.0 ml/kg/min (16–23.1); P = 0.18]. In contrast, V_E/VCO₂ slope was significantly higher in both cardiovascular only [29 (25–33) vs. 31 (27–37); P = 0.05] and cardiovascular with pulmonary complication groups [29 (25–33) vs. 37 (34–42); P<0.01)]. Logistic regression analysis showed V_E/VCO₂ slope [OR = 1.06; 95%CI (1.01–1.11); P = 0.01; AUC = 0.74], but not peak VO₂ to be independently associated with post-operative cardiovascular complications.

Conclusion

V_E/VCO₂ slope is superior to peak VO₂ for prediction of post-operative cardiovascular complications in lung resection candidates.

Provisional Decision-Making for Perioperative Blood Pressure Management: A Narrative Review

Blood pressure (BP) is a basic determinant for organ blood flow supply. Insufficient blood supply will cause tissue hypoxia, provoke cellular oxidative stress, and to some extent lead to organ injury. Perioperative BP is labile and dynamic, and intraoperative hypotension is common. It is unclear whether there is a causal relationship between intraoperative hypotension and organ injury. However, hypotension surely compromises perfusion and causes harm to some extent. Because the harm threshold remains unknown, various guidelines for intraoperative BP management have been proposed. With the pending definitions from robust randomized trials, it is reasonable to consider observational analyses suggesting that mean arterial pressures below 65 mmHg sustained for more than 15 minutes are associated with myocardial and renal injury. Advances in machine learning and artificial intelligence may facilitate the management of hemodynamics globally, including fluid administration, rather than BP alone. The previous mounting studies concentrated on associations between BP targets and adverse complications, whereas few studies were concerned about how to treat and multiple factors for decision-making. Hence, in this narrative review, we discussed the way of BP measurement and current knowledge about baseline BP extracting for surgical patients, highlighted the decision-making process for BP management with a view to providing pragmatic guidance for BP treatment in the clinical settings, and evaluated the merits of an automated blood control system in predicting hypotension.

Control of Postoperative Hypotension Using a Closed-Loop System for Norepinephrine Infusion in Patients After Cardiac Surgery: A Randomized Trial

BACKGROUND

Vasopressors are a cornerstone for the management of vasodilatory hypotension. Vasopressor infusions are currently adjusted manually to achieve a predefined arterial pressure target. We have developed a closed-loop vasopressor (CLV) controller to help correct hypotension more efficiently during the perioperative period. We tested the hypothesis that patients managed using such a system postcardiac surgery would present less hypotension compared to patients receiving standard management.

METHODS

A total of 40 patients admitted to the intensive care unit (ICU) after cardiac surgery were randomized into 2 groups for a 2-hour study period. In all patients, the objective was to maintain mean arterial pressure (MAP) between 65 and 75 mm Hg using norepinephrine. In the CLV group, the norepinephrine infusion was controlled via the CLV system; in the control group, it was adjusted manually by the ICU nurse. Fluid administration was standardized in both groups using an assisted fluid management system linked to an advanced hemodynamic monitoring system. The primary outcome was the percentage of time patients were hypotensive, defined as MAP <65 mm Hg, during the study period.

RESULTS

Over the 2-hour study period, the percentage of time with hypotension was significantly lower in the CLV group than that in the control group (1.4% [0.9-2.3] vs 12.5% [9.9-24.3]; location difference, -9.8% [95% CI, -5.4 to -15.9]; P < .001). The percentage of time with MAP between 65 and 75 mm Hg was also greater in the CLV group (95% [89-96] vs 66% [59-77]; location difference, 27.6% [95% CI, 34.3-19.0]; P < .001). The percentage of time with an MAP >75 mm Hg (and norepinephrine still being infused) was also significantly lower in patients in the CLV group than that in the control group (3.2% [1.9-5.4] vs 20.6% [8.9-32.5]; location difference, -17% [95% CI, -10 to -24]; P < .001).The number of norepinephrine infusion rate modifications over the study period was greater in the CLV group than that in the control group (581 [548-597] vs 13 [11-14]; location difference, 568 [578-538]; P < .001). No adverse event occurred during the study period in both groups.

CONCLUSIONS

Closed-loop control of norepinephrine infusion significantly decreases postoperative hypotension compared to manual control in patients admitted to the ICU after cardiac surgery.

Continuous monitoring of vital sign abnormalities; association to clinical complications in 500 postoperative patients

Background

Patients undergoing major surgery are at risk of complications, so‐called serious adverse events (SAE). Continuous monitoring may detect deteriorating patients by recording abnormal vital signs. We aimed to assess the association between abnormal vital signs inspired by Early Warning Score thresholds and subsequent SAEs in patients undergoing major abdominal surgery.

Methods

Prospective observational cohort study continuously monitoring heart rate, respiratory rate, peripheral oxygen saturation, and blood pressure for up to 96 h in 500 postoperative patients admitted to the general ward. Exposure variables were vital sign abnormalities, primary outcome was any serious adverse event occurring within 30 postoperative days. The primary analysis investigated the association between exposure variables per 24 h and subsequent serious adverse events.

Results

Serious adverse events occurred in 37% of patients, with 38% occurring during monitoring. Among patients with SAE during monitoring, the median duration of vital sign abnormalities was 272 min (IQR 110–447), compared to 259 min (IQR 153–394) in patients with SAE after monitoring and 261 min (IQR 132–468) in the patients without any SAE (p = .62 for all three group comparisons). Episodes of heart rate ≥110 bpm occurred in 16%, 7.1%, and 3.9% of patients in the time before SAE during monitoring, after monitoring, and without SAE, respectively (p < .002). Patients with SAE after monitoring experienced more episodes of hypotension ≤90 mm Hg/24 h (p = .001).

Conclusion

Overall duration of vital sign abnormalities at current thresholds were not significantly associated with subsequent serious adverse events, but more patients with tachycardia and hypotension had subsequent serious adverse events.

Trial registration

Clinicaltrials.gov, identifier NCT03491137.

Hypotensive Anesthesia Combined with Tranexamic Acid Reduces Perioperative Blood Loss in Simultaneous Bilateral Total Hip Arthroplasty: A Retrospective Cohort Study

OBJECTIVE

To assess the efficacy and safety of hypotensive anesthesia (HA) combined with tranexamic acid (TXA) for reducing perioperative blood loss in simultaneous bilateral total hip arthroplasty (SBTHA).

METHODS

In this retrospective cohort study, a total of 183 eligible patients (15 females and 168 males, 44.01 ± 9.29 years old) who underwent SBTHA from January 2015 to September 2020 at our medical center were enrolled for analysis. Fifty-nine patients received standard general anesthesia (Std-GA group), the other 85 and 39 patients received HA with an intraoperative mean arterial pressure between 70 and 80 mmHg (70-80 HA group) and below 70 mmHg (<70 HA group), respectively. TXA was administrated to all patients. Perioperative blood loss (total, dominant, and hidden), transfusion rate and volume, hemoglobin and hematocrit reduction, duration of operation and anesthesia, length of hospitalization, range of hip motion as well as postoperative complications were collected from hospital's electronic records and compared between groups.

RESULTS

All patients were followed for more than 3 months. Total blood loss in the two HA groups (1390.25 ± 595.67 ml and 1377.74 ± 423.46 ml, respectively) was significantly reduced compared with that in Std-GA group (1850.83 ± 800.73 ml, P < 0.001). Both dominant and hidden blood loss were dramatically decreased when HA was applied (both P < 0.001). Accordingly, the transfusion rate along with volume in 70-80 HA group (14.1%, 425.00 ± 128.81 ml) and <70 HA group (12.8%, 340.00 ± 134.16 ml) were reduced in comparison with those in Std-GA group (37.3%, 690.91 ± 370.21ml; P = 0.001 and P = 0.014, respectively). The maximal hemoglobin and hematocrit reduction in both HA groups were significantly less than those in Std-GA group (both P < 0.001). Of note, 70-80 and <70 HA groups exhibited comparable efficacy with no significant differences between them. Besides, significant difference in duration of surgery was found among groups (P = 0.044 and P < 0.001), while no differences in anesthesia time and postoperative range of hip motion were observed. Regarding complications, the incidence of both acute kidney injury and postoperative hypotension in <70 HA group was significantly higher than that in 70-80 HA and Std-GA groups (P = 0.014 and P < 0.001). Incidence of acute myocardial injury was similar among groups (P = 0.099) and no other severe complications or mortality were recorded.

CONCLUSION

The combination of HA with a mean arterial pressure (MAP) of 70-80 mmHg and TXA could significantly reduce blood loss and transfusion during SBTHA, in addition to shortening operation time and length of hospitalization, and with no increase in complications.

The burden of perioperative hypertension/hypotension: A systematic review

Study objective

Our goal is to review the outcomes of acute hypertensive/hypotensive episodes from articles published in the past 10 years that assessed the short- and long-term impact of acute hypertensive/hypotensive episodes in the perioperative setting.

Methods

We conducted a systematic peer review based upon PROSPERO and Cochrane Handbook protocols. The following study characteristics were collected: study type, author, year, population, sample size, their definition of acute hypertension, hypotension or other measures, and outcomes (probabilities, odds ratio, hazard ratio, and relative risk) and the p-values; and they were classified according to the type of surgery (cardiac and non-cardiac).

Results

A total of 3,680 articles were identified, and 66 articles fulfilled the criteria for data extraction. For the perioperative setting, the number of articles varies by outcome: 20 mortality, 16 renal outcomes, 6 stroke, 7 delirium and 34 other outcomes. Hypotension was reported to be associated with mortality (OR 1.02–20.826) as well as changes from the patient’s baseline blood pressure (BP) (OR 1.02–1.36); hypotension also had a role in the development of acute kidney injury (AKI) (OR 1.03–14.11). Postsurgical delirium was found in relation with BP lability (OR 1.018–1.038) and intra- and postsurgical hypotension (OR 1.05–1.22), and hypertension (OR 1.44–2.34). Increased OR (37.67) of intracranial hemorrhage was associated to postsurgical systolic BP >130 mmHg. There was a wide range of additional diverse outcomes related to hypo-, hypertension and BP lability.

Conclusions

The perioperative management of BP influences short- and long-term effects of surgical procedures in cardiac and non-cardiac interventions; these findings support the burden of BP fluctuations in this setting.

Postoperative blood pressure management in patients treated in the ICU after noncardiac surgery

PURPOSE OF REVIEW

Blood pressure management is a cornerstone of hemodynamic management in patients treated in the ICU after noncardiac surgery. Postoperative blood pressure management is challenging, because blood pressure alterations after surgery can be profound and have numerous causes.

RECENT FINDINGS

Postoperative blood pressure alterations are common in patients treated in ICUs after noncardiac surgery. There is increasing evidence that hypotension during the initial days after noncardiac surgery is associated with postoperative adverse outcomes including myocardial infarction and death, acute myocardial injury, acute kidney injury, major adverse cardiac or cerebrovascular events, and delirium. Thus, postoperative hypotension could be a modifiable risk factor for postoperative adverse outcomes. However, robust evidence for a causal relationship between postoperative blood pressure and postoperative adverse outcomes is still lacking.

SUMMARY

Future research on postoperative blood pressure management in patients treated in the ICU after noncardiac surgery needs to assess whether the prevention or treatment of postoperative blood pressure alterations - especially postoperative hypotension - reduces the incidence of postoperative adverse outcomes.

Application of perioperative hemodynamics today and potentials for tomorrow

Hemodynamic (HD) monitoring remains integral to the assessment and management of perioperative and critical care patients. This review article seeks to provide an update on the different types of flow-guided HD monitoring technologies available, highlight their limitations, and review the therapies associated with the application of these technologies. Additionally, we will also comment on the expanding roles of HD monitoring in the future.

Association between perioperative hypotension and postoperative delirium and atrial fibrillation after cardiac surgery: A post-hoc analysis of the DECADE trial

STUDY OBJECTIVE

To test the hypotheses that in adults having cardiac surgery with cardio-pulmonary bypass, perioperative hypotension increases the risk of delirium and atrial fibrillation during the initial five postoperative days.

DESIGN

Sub-analysis of the DECADE multi-center randomized trial.

SETTING

Patients who had cardiac surgery with cardiopulmonary bypass at the Cleveland Clinic.

INTERVENTIONS

In the underlying trial, patients were randomly assigned 1:1 to dexmedetomidine or normal saline placebo.

MEASUREMENTS

Intraoperative mean arterial pressures were recorded at 1-min intervals from arterial catheters or at 1-5-min intervals oscillometrically. Postoperative blood pressures were recorded every half-hour or more often. The co-primary outcomes were atrial fibrillation and delirium occurring between intensive care unit admission and the earlier of postoperative day 5 or hospital discharge. Delirium was assessed twice daily during the initial 5 postoperative days while patients remained hospitalized with the Confusion Assessment Method for the intensive care unit. Assessments were made by trained research fellows who were blinded to the dexmedetomidine administration.

MAIN RESULTS

There was no significant association between intraoperative hypotension and delirium, with an adjusted odds ratio of 0.94 (95% CI: 0.81, 1.09; P = 0.419) for a doubling in AUC of mean arterial pressure (MAP) <60 mmHg. An increase in intraoperative AUC of MAP <60 mmHg was not significantly associated with the odds of atrial fibrillation (adjusted odds ratio = 0.99; 95% CI: 0.87, 1.11; P = 0.819). Postoperative MAP <70 mmHg per hour 1.14 (97.5% CI: 1.04,1.26; P = 0.002) and MAP <80 mmHg per hour 1.05 (97.5%: 1.01, 1.10; P = 0.010) were significantly associated with atrial fibrillation.

CONCLUSIONS

In patients having cardiac surgery with cardio-pulmonary bypass, neither intraoperative nor postoperative hypotension were associated with delirium. Postoperative hypotension was associated with atrial fibrillation, although intraoperative hypotension was not.

Screening for postoperative vital signs abnormalities, and particularly hemodynamic ones, by continuous monitoring: protocol for the Biobeat-Postop cohort study

Background: Postoperative hypotension associated with postoperative morbidity and early mortality has been studied previously. Hypertension and other hemodynamic, respiratory, and temperature abnormalities have comparatively understudied during the first postoperative days.

Methods: This bi-centre observational cohort study will include 114 adult patients undergoing non-cardiac surgery hospitalized on an unmonitored general care floor and wearing a multi-signal wearable sensor, allowing remote monitoring ( Biobeat Technologies Ltd, Petah Tikva, Israel). The study will cover the first 72 hours after discharge of the patient from the post-anaesthesia care unit. Several thresholds will be used for each variable (arterial pressure, heart rate, respiratory rate, oxygen saturation, and skin temperature). Data obtained using the sensor will be compared to data obtained during the routine nurse follow-up. The primary outcome is hemodynamic abnormality. The secondary outcomes are postoperative respiratory and temperature abnormalities, artefacts and blank/null outputs from the wearable device, postoperative complications, and finally, the ease of use of the device. We hypothesize that remote monitoring will detect abnormalities in vital signs more often or more quickly than the detection by nurses’ routine surveillance.

Discussion: A demonstration of the ability of wireless sensors to outperform standard monitoring techniques paves the way for the creation of a loop which includes this monitoring mode, the automated creation of alerts, and the sending of these alerts to caregivers.

Trial registration: ClinicalTrials.gov, NCT04585178. Registered on October 14, 2020

Assessment of Myocardial Function During Blood Pressure Manipulations Using Feature Tracking Cardiovascular Magnetic Resonance

Background: Coronary autoregulation is a feedback system, which maintains near-constant myocardial blood flow over a range of mean arterial pressure (MAP). Yet in emergency or peri-operative situations, hypotensive or hypertensive episodes may quickly arise. It is not yet established how rapid blood pressure changes outside of the autoregulation zone (ARZ) impact left (LV) and right ventricular (RV) function. Using cardiovascular magnetic resonance (CMR) imaging, measurements of myocardial tissue oxygenation and ventricular systolic and diastolic function can comprehensively assess the heart throughout a range of changing blood pressures.

Design and methods: In 10 anesthetized swine, MAP was varied in steps of 10–15 mmHg from 29 to 196 mmHg using phenylephrine and urapidil inside a 3-Tesla MRI scanner. At each MAP level, oxygenation-sensitive (OS) cine images along with arterial and coronary sinus blood gas samples were obtained and blood flow was measured from a surgically implanted flow probe on the left anterior descending coronary artery. Using CMR feature tracking-software, LV and RV circumferential systolic and diastolic strain parameters were measured from the myocardial oxygenation cines.

Results: LV and RV peak strain are compromised both below the lower limit (LV: Δ1.2 ± 0.4%, RV: Δ4.4 ± 1.2%, p < 0.001) and above the upper limit (LV: Δ2.1 ± 0.4, RV: Δ5.4 ± 1.4, p < 0.001) of the ARZ in comparison to a baseline of 70 mmHg. LV strain demonstrates a non-linear relationship with invasive and non-invasive measures of oxygenation. Specifically for the LV at hypotensive levels below the ARZ, systolic dysfunction is related to myocardial deoxygenation (β = −0.216, p = 0.036) in OS-CMR and both systolic and diastolic dysfunction are linked to reduced coronary blood flow (peak strain: β = −0.028, p = 0.047, early diastolic strain rate: β = 0.026, p = 0.002). These relationships were not observed at hypertensive levels.

Conclusion: In an animal model, biventricular function is compromised outside the coronary autoregulatory zone. Dysfunction at pressures below the lower limit is likely caused by insufficient blood flow and tissue deoxygenation. Conversely, hypertension-induced systolic and diastolic dysfunction points to high afterload as a cause. These findings from an experimental model are translatable to the clinical peri-operative environment in which myocardial deformation may have the potential to guide blood pressure management, in particular at varying individual autoregulation thresholds.

Associations between intraoperative and post-anesthesia care unit hypotension and surgical ward hypotension

STUDY OBJECTIVE

To test whether patients who experience hypotension in the post-anesthesia care unit or during surgery are most likely to experience hypotension on surgical wards.

DESIGN

A prediction study using data from two randomized controlled trials.

SETTING

Operating room, post-anesthesia care unit, and surgical ward.

PATIENTS

550 adult patients having abdominal surgery with ASA physical status I-IV.

INTERVENTIONS

Blood pressure measurement per routine intraoperatively, and with continuous non-invasive monitoring postoperatively.

MEASUREMENTS

The primary predictors were minimum mean arterial pressure (<60, <65, <70 and < 80 mmHg) and minimum systolic blood pressure (<70, <75, <80, <85 mmHg) in the post-anesthesia care unit. The secondary predictors were intraoperative minimum blood pressures with the same thresholds as the primary ones. Our outcome was ward hypotension defined as mean pressure < 70 mmHg or systolic pressure < 85 mmHg. A threshold was considered clinically useful if both sensitivity and specificity exceeded 0.75.

MAIN RESULTS

Minimum mean and systolic pressures in the post-anesthesia care unit similarly predicted ward mean or systolic hypotension, with the areas under the curves near 0.74. The best performing threshold was mean pressure < 80 mmHg in the post-anesthesia care unit which had a sensitivity of 0.41 (95% confidence interval [CI], 0.35, 0.47) and specificity of 0.91 (95% CI, 0.87, 0.94) for ward mean pressure < 70 mmHg and a sensitivity of 0.44 (95% CI, 0.37, 0.51) and specificity of 0.88 (95% CI, 0.84, 0.91) for ward systolic pressure < 85 mmHg. The areas under the curves using intraoperative hypotension to predict ward hypotension were roughly similar at about 0.60, with correspondingly low sensitivity and specificity.

CONCLUSIONS

Intraoperative hypotension poorly predicted ward hypotension. Pressures in the post-anesthesia care unit were more predictive, but the combination of sensitivity and specificity remained poor. Unless far better predictors are identified, all surgical inpatients should be considered at risk for postoperative hypotension.

The effect of intra-operative hypotension on acute kidney injury, postoperative mortality and length of stay following emergency hip fracture surgery

The association between intra-operative hypotension and postoperative acute kidney injury, mortality and length of stay has not been comprehensively evaluated in a large single-centre hip fracture population. We analysed electronic anaesthesia records of 1063 patients undergoing unilateral hip fracture surgery, collected from 2015 to 2018. Acute kidney injury, 3-, 30- and 365-day mortality and length of stay were evaluated to assess the relationship between intra-operative hypotension absolute values (≤ 55, 60, 65, 70 and 75 mmHg) and duration of hypotension. The rate of acute kidney injury was 23.7%, mortality at 3-, 30- and 365 days was 3.7%, 8.0% and 25.3%, respectively, and median (IQR [range]) length of stay 8 (6-12 [0-99]) days. Median (IQR [range]) time ≤ MAP 55, 60, 65, 70 and 75 mmHg was 0 (0-0.5[0-72.1]); 0 (0-4.4 [0-104.9]); 2.2 (0-8.7 [0-144.2]); 6.6 (2.2-19.7 [0-198.8]); 17.5 (6.6-37.1 [0-216.3]) minutes, and percentage of surgery time below these thresholds was 1%, 2.5%, 7.9%, 12% and 21% respectively. There were some univariate associations between hypotension and mortality; however, these were no longer evident in multivariable analysis. Multivariable analysis found no association between hypotension and acute kidney injury. Acute kidney injury was associated with male sex, antihypertensive medications and cardiac/renal comorbidities. Three-day mortality was associated with delay to surgery ? 48 hours, whilst 30-day and 365-day mortality was associated with delay to surgery ≥ 48 hours, impaired cognition and cardiac/renal comorbidities. While the rate of acute kidney injury was similar to other studies, use of vasopressors and fluids to reduce the time spent at hypotensive levels failed to reduce this complication. Intra-operative hypotension at the levels observed in this cohort may not be an important determinant of acute kidney injury, postoperative mortality and length of stay.

Association of perioperative hypotension with subsequent greater healthcare resource utilization

STUDY OBJECTIVE

Determine if perioperative hypotension, a modifiable risk factor, is associated with increased postoperative healthcare resource utilization (HRU).

DESIGN

Retrospective cohort study.

SETTING

Multicenter using the Optum® electronic health record database.

PATIENTS

Patients discharged to the ward after non-cardiac, non-obstetric surgeries between January 1, 2008 and December 31, 2017 with six months of data, before and after the surgical visit.

INTERVENTIONS/EXPOSURE

Perioperative hypotension, a binary variable (presence/absence) at an absolute MAP of ≤65-mmHg, measured during surgery and within 48-h after, to dichotomize patients with greater versus lesser hypotensive exposures.

MEASUREMENTS

Short-term HRU defined by postoperative length-of-stay (LOS), discharge to a care facility, and 30-day readmission following surgery discharge. Mid-term HRU (within 6 months post-discharge) quantified via number of outpatient and emergency department (ED) visits, and readmission LOS.

MAIN RESULTS

42,800 distinct patients met study criteria and 37.5% experienced perioperative hypotension. After adjusting for study covariates including patient demographics and comorbidities, patients with perioperative hypotension had: longer LOS (4.01 vs. 3.83 days; LOS ratio, 1.05; 95% CI, 1.04-1.06), higher odds of discharge to a care facility (OR, 1.18; 95% CI, 1.12-1.24; observed rate 22.1% vs. 18.1%) and of 30-day readmission (OR, 1.22; 95% CI, 1.11-1.33; observed rate 6.2% vs. 5.0%) as compared to the non-hypotensive population (all outcomes, p < 0.001). During 6-month follow-up, patients with perioperative hypotension showed significantly greater HRU regarding number of ED visits (0.34 vs. 0.31 visits; visit ratio, 1.10; 95% CI, 1.05-1.15) and readmission LOS (1.06 vs. 0.92 days; LOS ratio, 1.15; 95% CI, 1.07-1.24) but not outpatient visits (10.47 vs. 10.82; visit ratio, 0.97; 95% CI, 0.95-0.99) compared to those without hypotension. There was no difference in HRU during the 6-month period before qualifying surgery.

CONCLUSIONS

We report a significant association of perioperative hypotension with an increase in HRU, including additional LOS and readmissions, both important contributors to overall medical costs.

[Effectiveness and safety of tranexamic acid combined with intraoperative controlled hypotension on reducing perioperative blood loss in primary total hip arthroplasty]

Objective

To evaluate the effectiveness and safety of tranexamic acid (TXA) combined with intraoperative controlled hypotension (ICH) for reducing perioperative blood loss in primary total hip arthroplasty (THA).

Methods

The clinical data of 832 patients with initial THA due to osteonecrosis of femoral head between January 2017 and July 2020 were retrospectively analyzed. All patients received TXA treatment, and 439 patients (hypotension group) received ICH treatment with an intraoperative mean arterial pressure (MAP) below 80 mm Hg (1 mm Hg=0.133 kPa) while 393 patients (normotension group) received standard general anesthesia with no special invention on blood pressure. There was no significant difference in age, gender, body mass index, American Society of Anesthesiologists (ASA) classification, basic arterial pressure, hip range of motion, internal diseases, preoperative hemoglobin (HB) and hematocrit (HCT), coagulation function, surgical approach, and TXA dosage between the two groups ( P>0.05). The perioperative blood loss and blood transfusion, anesthesia and operation time, hospitalization stay, postoperative range of motion, and complications were recorded and compared between the two groups. The patients were further divided into MAP<70 mm Hg group (group A), MAP 70-80 mm Hg group (group B), and normotension group (group C). The perioperative blood loss and postoperative complications were further analyzed to screen the best range of blood pressure.

Results

The intraoperative MAP, total blood loss, dominant blood loss, recessive blood loss, blood transfusion rate and blood transfusion volume, anesthesia time, operation time, and hospitalizarion stay in the hypotension group were significantly lower than those in the normotension group ( P<0.05). The postoperative hip flexion range of motion in the hypotension group was significantly better than that of the normotension group ( Z=2.743, P=0.006), but there was no significant difference in the abduction range of motion between the two groups ( Z=0.338, P=0.735). In terms of postoperative complications, the incidence of postoperative hypotension in the hypotension group was significantly higher than that in the normotension group ( χ ²=6.096, P=0.014), and there was no significant difference in the incidence of other complications ( P>0.05). There was no stroke, pulmonary embolism, or deep vein thrombosis in the two groups, and no patients died during hospitalization. Subgroup analysis showed that there was no significant difference in total blood loss, dominant blood loss, and recessive blood loss in groups A and B during the perioperative period ( P>0.05), which were significantly lower than those in group C ( P<0.05). There was no significant difference in blood transfusion rate, blood transfusion volume, and incidence of acute myocardial injury between 3 groups ( P>0.05); the incidence of acute kidney injury in group A was significantly higher than that in group B, and the incidence of postoperative hypotension in group A was significantly higher than that in groups B and C ( P<0.05), but no significant difference was found between groups B and C ( P>0.05).

Conclusion

The combination of TXA and ICH has a synergistic effect. Controlling the intraoperative MAP at 70-80 mm Hg can effectively reduce the perioperative blood loss during the initial THA, and it is not accompanied by postoperative complications.

Failure to detect ward hypoxaemia and hypotension: contributions of insufficient assessment frequency and patient arousal during nursing assessments

BACKGROUND

Postoperative hypotension and hypoxaemia are common and often unrecognised. With intermittent nursing vital signs, hypotensive or hypoxaemic episodes might be missed because they occur between scheduled measurements, or because the process of taking vital signs arouses patients and temporarily improves arterial blood pressure and ventilation. We therefore estimated the fraction of desaturation and hypotension episodes that did not overlap nursing assessments and would therefore usually be missed. We also evaluated the effect of taking vital signs on blood pressure and oxygen saturation.

METHODS

We estimated the fraction of desaturated episodes (arterial oxygen saturation <90% for at least 90% of the time within 30 continuous minutes) and hypotensive episodes (MAP <70 mm Hg for 15 continuous minutes) that did not overlap nursing assessments in patients recovering from noncardiac surgery. We also evaluated changes over time before and after nursing visits.

RESULTS

Among 782 patients, we identified 878 hypotensive episodes and 2893 desaturation episodes, of which 79% of the hypotensive episodes and 82% of the desaturation episodes did not occur within 10 min of a nursing assessment and would therefore usually be missed. Mean BP and oxygen saturation did not improve by clinically meaningful amounts during nursing vital sign assessments.

CONCLUSIONS

Hypotensive and desaturation episodes are mostly missed because vital sign assessments on surgical wards are sparse, rather than being falsely negative because the assessment process itself increases blood pressure and oxygen saturation. Continuous vital sign monitoring will detect more disturbances, potentially giving clinicians time to intervene before critical events occur.

Intraoperative hypotension and complications after vascular surgery: A scoping review

BACKGROUND

Intraoperative hypotension during major surgery is associated with adverse health outcomes. This phenomenon represents a potentially important therapeutic target for vascular surgery patients, who may be uniquely vulnerable to intraoperative hypotension. This review summarizes current evidence regarding the impact of intraoperative hypotension on postoperative complications in patients undergoing vascular surgery, focusing on potentially modifiable procedure- and patient-specific risk factors.

METHODS

A scoping review of the literature from Embase, MEDLINE, and PubMed databases was conducted from inception to December 2019 to identify articles related to the effects of intraoperative hypotension on patients undergoing vascular surgery.

RESULTS

Ninety-two studies met screening criteria; 9 studies met quality and inclusion criteria. Among the 9 studies that defined intraoperative hypotension objectively, there were 9 different definitions. Accordingly, the reported incidence of intraoperative hypotension ranged from 8% to 88% (when defined as a fall in systolic blood pressure of >30 mm Hg or mean arterial pressure <65). The results demonstrated that intraoperative hypotension is an independent risk factor for longer hospital length of stay, myocardial injury, acute kidney injury, postoperative mechanical ventilation, and early mortality. Vascular surgery patients with comorbid conditions that confer increased vulnerability to hypoperfusion and ischemia appear to be susceptible to the adverse effects of intraoperative hypotension.

CONCLUSION

There is no validated, consensus definition of intraoperative hypotension or other hemodynamic parameters associated with increased risk for adverse outcomes. Despite these limitations, the weight of evidence suggests that intraoperative hypotension is common and associated with major postoperative complications in vascular surgery patients.

Dose-response effect of postprocedural elevated cardiac troponin level on adverse clinical outcomes following adult noncardiac surgery: a systematic review protocol of prospective studies

INTRODUCTION

Myocardial injury after noncardiac surgery has been recognised as an important complication associated with short-term and long-term morbidity and mortality. However, whether a higher level of postoperative cardiac troponin (cTn) is associated with a higher incidence of major complications remains controversial. Hence, we will conduct a comprehensive dose-response meta-analysis based on all relevant prospective studies to quantitatively evaluate the association between elevated postoperative cTn levels and short-/long-term adverse clinical outcomes following adult noncardiac surgery.

METHODS

We will search the PubMed, EMBase, Cochrane Library, ISI Knowledge via Web of Science, China National Knowledge Infrastructure, Wanfang and VIP databases (from inception until October 2020) to identify all prospective cohort studies using the relevant keywords. The primary outcome will be all-cause mortality. The secondary outcomes will include cardiovascular mortality and major adverse cardiovascular events (MACEs). Univariable or multivariable meta-regression and subgroup analyses will be conducted for the comparison between elevated versus nonelevated categories of postoperative cTn levels. Sensitivity analyses will be used to assess the robustness of our results by removing each included study at one time to obtain and evaluate the remaining overall estimates of all-cause mortality or MACE. To conduct a dose-response meta-analysis for the potential linear or restricted cubic spline regression relationship between postoperative elevated cTn levels and all-cause mortality or MACE, studies with three or more categories will be included.

ETHICS AND DISSEMINATION

Ethical approval is waived for the systematic review protocol according to the Institutional Review Board/Independent Ethics Committee of Fuwai Hospital. This meta-analysis will be disseminated through a peer-reviewed journal for publication and conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42020173175.

Postoperative Hypotension and Adverse Clinical Outcomes in Patients Without Intraoperative Hypotension, After Noncardiac Surgery

BACKGROUND

Postoperative hypotension (POH) is associated with major adverse events. However, little is known about the association of blood pressure thresholds and outcomes in postoperative patients without intraoperative hypotension (IOH) on the general-care ward. We evaluated the association of POH with major adverse cardiac or cerebrovascular events (MACCE) in patients without IOH.

METHODS

This retrospective analysis included 67,968 noncardiac patient-procedures (2008-2017) for patients discharged to the ward with postoperative mean arterial pressure (MAP) readings, managed for ≥48 hours postsurgery, with no evidence of IOH. The primary outcome was 30-day MACCE evaluated by postoperative MAP thresholds: ≤75, ≤65, and ≤55 mm Hg (POH defined as a single measurement below threshold). Secondary outcomes included all-cause mortality (30-/90-day), 30-day acute myocardial infarction, 30-day acute ischemic stroke, 30-day readmission, 7-day acute kidney injury, and 30-day readmission. Associations between POH and adverse events were also evaluated in a cohort (#2) of 16,034 patient-procedures with IOH (intraoperative MAP ≤65 mm Hg).

RESULTS

In patients without IOH, exposure to POH was not associated with MACCE at any investigated MAP threshold (P < .016 was considered significant: ≤75 mm Hg, hazard ratio [HR] 1.18 [98.4% confidence interval {CI} 0.99-1.39], P = .023; ≤65 mm Hg, HR 1.18 [0.99-1.41], P = .028; ≤55 mm Hg, HR 1.23 [0.90-1.71], P = .121); however, associations were observed at all MAP thresholds for secondary outcomes of acute kidney injury and 30-day readmission, for 30-/90-day mortality for MAP ≤65 mm Hg, and 90-day mortality for MAP ≤55 mm Hg, compared to those without POH. No associations were detected between POH and secondary outcomes of acute ischemic stroke or acute myocardial infarction at any MAP threshold. No interaction between POH and IOH was found when we evaluated the association of POH on outcomes in the data set including all patients, regardless of IOH status (P values for interaction terms nonsignificant). When the interaction term was utilized, the association between POH without IOH and MACCE was significant for MAP ≤75 mm Hg (HR 1.20 [1.01-1.41]) and MAP ≤65 mm Hg (HR 1.21 [1.02-1.45]), but not MAP ≤55 mm Hg. Cohort #2 (POH with IOH) showed largely similar results for MACCE: not significant for MAP ≤75 and ≤65 mm Hg, but significant for MAP ≤55 mm Hg (HR 1.53 [1.05-2.22], P = .006).

CONCLUSIONS

POH in patients without IOH was not associated with MACCE at any MAP investigated. No interaction was identified between POH and IOH. Large prospective randomized trials are necessary to develop better evidence and inform clinicians the value of postoperative blood pressure management.