Association between Intraoperative Hypotension and Myocardial Injury after Vascular Surgery

Risk factors and outcomes of urosepsis in patients with calculous pyonephrosis receiving surgical intervention: a single-center retrospective study

Background

Urosepsis is a catastrophic complication, which can easily develop into septic shock and lead to death if not diagnosed early and effectively treated in time. However, there is a lack of evidence on the risk factors and outcomes in calculous pyonephrosis patients. Therefore, this study was conducted to identify risk factors and outcomes of intra- and postoperative urosepsis in this particular population.

Methods

Clinical data of 287 patients with calculous pyonephrosis were collected. In the univariate and multivariate analysis, all patients were divided into urosepsis group and non-urosepsis group. The diagnosis of urosepsis was mainly on the basis of the criteria of American College of Chest Physicians (ACCP)/Society of Critical Care Medicine (SCCM). Patient characteristics and outcomes data were analyzed, and risk factors were assessed by binary logistic regression analysis.

Results

Of 287 patients, 41 (14.3%) acquired urosepsis. Univariate analysis showed that white blood cell (WBC > 10*10^9/L) before surgery (P = 0.027), surgery types (P = 0.009), hypotension during surgery (P < 0.001) and urgent surgery (P < 0.001) were associated with intra- and postoperative urosepsis for calculous pyonephrosis patients. In multivariate analysis, hypotension during surgery and urgent surgery were closely related to intra- and postoperative urosepsis. Outcome analysis suggested that patients developing urosepsis had a longer intensive care unit (ICU) stay and postoperative hospital stay and higher mortality.

Conclusions

Hypotension during surgery and urgent surgery were risk factors of intra- and postoperative urosepsis for calculous pyonephrosis patients, which may lead to a prolonged ICU stay, postoperative hospital stay and higher mortality.

Closed-loop hemodynamic management

As the operating room and intensive care settings become increasingly complex, the required vigilance practitioners must dedicate to a wide array of clinical systems has increased concordantly. The resulting shortage of available attention to these various clinical tasks creates a vacuum for the introduction of systems that can administer well-established goal-directed therapies without significant provider feedback. Recently, there has been an explosion of academic exploration into creating such automated systems, with a strong specific focus on hemodynamic control. Within this field, the largest focus has been on goal-directed fluid therapy as systems automating vasopressor administration have only recently become viable options. Our goal in this review article is to summarize the validity of the relevant goal-directed hemodynamic systems and explore the expanding role of automation within these systems.

Perioperative Quality Initiative consensus statement on intraoperative blood pressure, risk and outcomes for elective surgery

BACKGROUND

Intraoperative mortality is now rare, but death within 30 days of surgery remains surprisingly common. Perioperative myocardial infarction is associated with a remarkably high mortality. There are strong associations between hypotension and myocardial injury, myocardial infarction, renal injury, and death. Perioperative arterial blood pressure management was thus the basis of a Perioperative Quality Initiative consensus-building conference held in London in July 2017.

METHODS

The meeting featured a modified Delphi process in which groups addressed various aspects of perioperative arterial pressure.

RESULTS

Three consensus statements on intraoperative blood pressure were established. 1) Intraoperative mean arterial pressures below 60-70 mm Hg are associated with myocardial injury, acute kidney injury, and death. Injury is a function of hypotension severity and duration. 2) For adult non-cardiac surgical patients, there is insufficient evidence to recommend a general upper limit of arterial pressure at which therapy should be initiated, although pressures above 160 mm Hg have been associated with myocardial injury and infarction. 3) During cardiac surgery, intraoperative systolic arterial pressure above 140 mm Hg is associated with increased 30 day mortality. Injury is a function of arterial pressure severity and duration.

CONCLUSIONS

There is increasing evidence that even brief durations of systolic arterial pressure <100 mm Hg and mean arterial pressure <60-70 mm Hg are harmful during non-cardiac surgery.

Clinical standards for patient blood management and perioperative hemostasis and coagulation management. Position Paper of the Italian Society of Anesthesia, Analgesia, Resuscitation and Intensive Care (SIAARTI)

Patient blood management is currently defined as the application of evidence based medical and surgical concepts designed to maintain hemoglobin (Hb), optimize hemostasis and minimize blood loss to improve patient outcome. Blood management focus on the perioperative management of patients undergoing surgery or other invasive procedures in which significant blood loss occurs or is expected. Preventive strategies are emphasized to identify and manage anemia, reduce iatrogenic blood losses, optimize hemostasis (e.g. pharmacologic therapy, and point of care testing); establish decision thresholds for the appropriate administration of blood therapy. This goal was motivated historically by known blood risks including transmissible infectious disease, transfusion reactions, and potential effects of immunomodulation. Patient blood management has been recognized by the World Health Organization (WHO) as the new standard of care and has urged all 193-member countries of WHO to implement this concept. There is a pressing need for this new "standard of care" so as to reduce blood transfusion and promote the availability of transfusion alternatives. Patient blood management therefore encompasses an evidence-based medical and surgical approach that is multidisciplinary (transfusion medicine specialists, surgeons, anesthesiologists, and critical care specialists) and multiprofessional (physicians, nurses, pump technologists and pharmacists). The Italian Society of Anesthesia, Analgesia, Resuscitation and Intensive Care (SIAARTI) organized a consensus project involving a Task Force of expert anesthesiologists that reviewing literature provide appropriate levels of care and good clinical practices. Hence, this article focuses on achieving goals of PBM in the perioperative period.

Impact of postoperative mean arterial pressure on the incidence of postoperative complications after hepatic resection for primary liver malignancy

PURPOSE

We conducted this study to evaluate the impact of the postoperative mean arterial pressure (MAP) on surgical complications after hepatic resection.

METHODS

The subjects of this study were 199 patients who underwent hepatic resection for primary liver malignancy between 2004 and 2013. A clinically relevant postoperative complication was defined as a Clavien-Dindo grade ≥ III complication.

RESULTS

Based on an MAP cut-off value of 81.1 mmHg, the patients were grouped as follows: low MAP on both postoperative days (PODs) 1 and 2 (continuously low MAP), normal MAP on both PODs 1 and 2 (normal MAP), and others (transiently low MAP). The continuously low MAP group had the highest incidence of complications and the normal MAP group had the lowest incidence of complications compared with the expected incidence for this cohort (p < 0.01 and p = 0.01, respectively). Multivariate analysis revealed that both a continuously and transiently low MAP were independent predictors of postoperative complications (p = 0.03 and p < 0.01, respectively). Among the subtypes of complications, a low MAP had a significant relationship with ascites/pleural effusion and respiratory complications (p < 0.01 and p = 0.03, respectively).

CONCLUSIONS

A low MAP on POD 1 and/or 2 is an independent predictor of postoperative complications.

The triple variable index combines information generated over time from common monitoring variables to identify patients expressing distinct patterns of intraoperative physiology

Background

Mean arterial pressure (MAP), bispectral index (BIS), and minimum alveolar concentration (MAC) represent valuable, yet dynamic intraoperative monitoring variables. They provide information related to poor outcomes when considered together, however their collective behavior across time has not been characterized.

Methods

We have developed the Triple Variable Index (TVI), a composite variable representing the sum of z-scores from MAP, BIS, and MAC values that occur together during surgery. We generated a TVI expression profile, defined as the sequential TVI values expressed across time, for each surgery where concurrent MAP, BIS, and MAC monitoring occurred in an adult patient (≥18 years) at the University of Pittsburgh Medical Center between January and July 2014 (n = 5296). Patterns of TVI expression were identified using k-means clustering and compared across numerous patient, procedure, and outcome characteristics. TVI and the triple low state were compared as prediction models for 30-day postoperative mortality.

Results

The median frequency MAP, BIS, and MAC were recorded was one measurement every 3, 5, and 5 min. Three expression patterns were identified: elevated, mixed, and depressed. The elevated pattern displayed the highest average MAP, BIS, and MAC values (86.5 mmHg, 45.3, and 0.98, respectively), while the depressed pattern displayed the lowest values (76.6 mmHg, 38.0, 0.66). Patterns (elevated, mixed, depressed) were distinct across the following characteristics: average patient age (52, 53, 54 years), American Society of Anesthesiologists Physical Status 4 (6.7, 16.1, 27.3%) and 5 (0.1, 0.6, 1.6%) categories, cardiac (2.2, 6.5, 16.1%) and emergent (5.8, 10.5, 12.8%) surgery, cardiopulmonary bypass use (0.3, 2.6, 9.8%), intraoperative medication administration including etomidate (3.0, 7.3, 12.6%), hydromorphone (47.6, 26.3, 25.2%), ketamine (11.2, 4.6, 3.0%), dexmedetomidine (18.4, 16.6, 13.6%), phenylephrine (74.0, 74.8, 83.0), epinephrine (2.0, 6.0, 18.0%), norepinephrine (2.4, 7.5, 21.2%), vasopressin (3.4, 7.6, 21.0%), succinylcholine (74.0, 69.0, 61.9%), intraoperative hypotension (28.8, 33.0, 52.3%) and the triple low state (9.4, 30.3, 80.0%) exposure, and 30-day postoperative mortality (0.8, 2.7, 5.6%). TVI was a better predictor of patients that died or survived in the 30 days following surgery compared to cumulative triple low state exposure (AUC 0.68 versus 0.62, p < 0.05).

Conclusions

Surgeries that share similar patterns of TVI expression display distinct patient, procedure, and outcome characteristics.

Electronic supplementary material

The online version of this article (10.1186/s12874-019-0660-9) contains supplementary material, which is available to authorized users.

Causes and prevention of postoperative myocardial injury

Over the past few years non-cardiac surgery has been recognised as a serious circulatory stress test which may trigger cardiovascular events such as myocardial infarction, in particular in patients at high risk. Detection of these postoperative cardiovascular events is difficult as clinical symptoms often go unnoticed. To improve detection, guidelines advise to perform routine postoperative assessment of cardiac troponin. Troponin elevation - or postoperative myocardial injury - can be caused by myocardial infarction. However, also non-coronary causes, such as cardiac arrhythmias, sepsis and pulmonary embolism, may play a role in a considerable number of patients with postoperative myocardial injury. It is crucial to acquire more knowledge about the underlying mechanisms of postoperative myocardial injury because effective prevention and treatment options are lacking. Preoperative administration of beta-blockers, aspirin, statins, clonidine, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, and preoperative revascularisation have all been investigated as preventive options. Of these, only statins should be considered as the initiation or reload of statins may reduce the risk of postoperative myocardial injury. There is also not enough evidence for intraoperative measures such blood pressure optimisation or intensified medical therapy once patients have developed postoperative myocardial injury. Given the impact, better preoperative identification of patients at risk of postoperative myocardial injury, for example using preoperatively measured biomarkers, would be helpful to improve cardiac optimisation.

Blood Pressure and End-tidal Carbon Dioxide Ranges during Aneurysm Occlusion and Neurologic Outcome after an Aneurysmal Subarachnoid Hemorrhage

EDITOR’S PERSPECTIVE

What We Already Know about This Topic

It remains unknown what end-tidal carbon dioxide and mean arterial pressure are optimal for surgical management of patients with an aneurysmal subarachnoid hemorrhage

What This Article Tells Us That Is New

The investigators retrospectively evaluated 1,099 patients who had endovascular coiling or surgical clipping for subarachnoid hemorrhages

There were no clinically important or statistical significant associations between either end-tidal carbon dioxide or mean arterial pressure thresholds and Glasgow Outcome Scale at discharge or three months

Other prognostic factors are more important than carbon dioxide and blood pressure, at least within the observed clinical ranges

Background

Hypocapnia, hypotension, and hypertension during aneurysm occlusion in patients with an aneurysmal subarachnoid hemorrhage may lead to a poor prognosis, but evidence for end-tidal carbon dioxide (ETco2) and mean arterial pressure (MAP) targets is lacking. Within the ranges of standardized treatment, the authors aimed to study the association between hypocapnia (Paco2 &lt; 35 mmHg), hypotension (MAP &lt; 80 mmHg), and hypertension (MAP &gt;100 mmHg) during general anesthesia for aneurysm occlusion and neurologic outcome.

Methods

This retrospective observational study included patients who underwent early aneurysm occlusion after an aneurysmal subarachnoid hemorrhage under general anesthesia. ETco2 and MAP were summarized per patient as the mean and time-weighted average area under the curve for various absolute (ETco2 &lt; 30, &lt; 35, &lt; 40, &lt; 45 mmHg; and MAP &lt; 60, &lt; 70, &lt; 80, &gt; 90, &gt; 100 mmHg) and relative thresholds (MAP &lt; 70%, &lt; 60%, &lt; 50%). Clinical outcome was assessed with the Glasgow Outcome Scale at discharge and at three months, as primary and secondary outcome measure, respectively.

Results

Endovascular coiling was performed in 578 patients, and 521 underwent neurosurgical clipping. Of these 1,099 patients, 447 (41%) had a poor neurologic outcome at discharge. None of the ETco2 and MAP ranges found within the current clinical setting were associated with a poor neurologic outcome at discharge, with an adjusted risk ratio for any ETco2 value less than 30 mmHg of 0.95 (95% CI, 0.81 to 1.10; P &lt; 0.496) and an adjusted risk ratio for any MAP less than 60 mmHg of 0.94 (95% CI, 0.78 to 1.14; P &lt; 0.530). These results were not influenced by preoperative neurologic condition, treatment modality and timing of the intervention. Comparable results were obtained for neurologic outcome at three months.

Conclusions

Within a standardized intraoperative treatment strategy in accordance with current clinical consensus, hypocapnia, hypotension, and hypertension during aneurysm occlusion were not found to be associated with a poor neurologic outcome at discharge in patients with an aneurysmal subarachnoid hemorrhage.

Cardiac vagal dysfunction and myocardial injury after non-cardiac surgery: a planned secondary analysis of the measurement of Exercise Tolerance before surgery study

Background

The aetiology of perioperative myocardial injury is poorly understood and not clearly linked to pre-existing cardiovascular disease. We hypothesised that loss of cardioprotective vagal tone [defined by impaired heart rate recovery ≤12 beats min⁻¹ (HRR ≤12) 1 min after cessation of preoperative cardiopulmonary exercise testing] was associated with perioperative myocardial injury.

Methods

We conducted a pre-defined, secondary analysis of a multi-centre prospective cohort study of preoperative cardiopulmonary exercise testing. Participants were aged ≥40 yr undergoing non-cardiac surgery. The exposure was impaired HRR (HRR≤12). The primary outcome was postoperative myocardial injury, defined by serum troponin concentration within 72 h after surgery. The analysis accounted for established markers of cardiac risk [Revised Cardiac Risk Index (RCRI), N-terminal pro-brain natriuretic peptide (NT pro-BNP)].

Results

A total of 1326 participants were included [mean age (standard deviation), 64 (10) yr], of whom 816 (61.5%) were male. HRR≤12 occurred in 548 patients (41.3%). Myocardial injury was more frequent amongst patients with HRR≤12 [85/548 (15.5%) vs HRR>12: 83/778 (10.7%); odds ratio (OR), 1.50 (1.08–2.08); P=0.016, adjusted for RCRI). HRR declined progressively in patients with increasing numbers of RCRI factors. Patients with ≥3 RCRI factors were more likely to have HRR≤12 [26/36 (72.2%) vs 0 factors: 167/419 (39.9%); OR, 3.92 (1.84–8.34); P<0.001]. NT pro-BNP greater than a standard prognostic threshold (>300 pg ml⁻¹) was more frequent in patients with HRR≤12 [96/529 (18.1%) vs HRR>12 59/745 (7.9%); OR, 2.58 (1.82–3.64); P<0.001].

Conclusions

Impaired HRR is associated with an increased risk of perioperative cardiac injury. These data suggest a mechanistic role for cardiac vagal dysfunction in promoting perioperative myocardial injury.

Photoplethysmographic characterization of vascular tone mediated changes in arterial pressure: an observational study

To determine whether a classification based on the contour of the photoplethysmography signal (PPGc) can detect changes in systolic arterial blood pressure (SAP) and vascular tone. Episodes of normotension (SAP 90-140 mmHg), hypertension (SAP > 140 mmHg) and hypotension (SAP < 90 mmHg) were analyzed in 15 cardiac surgery patients. SAP and two surrogates of the vascular tone, systemic vascular resistance (SVR) and vascular compliance (Cvasc = stroke volume/pulse pressure) were compared with PPGc. Changes in PPG amplitude (foot-to-peak distance) and dicrotic notch position were used to define 6 classes taking class III as a normal vascular tone with a notch placed between 20 and 50% of the PPG amplitude. Class I-to-II represented vasoconstriction with notch placed > 50% in a small PPG, while class IV-to-VI described vasodilation with a notch placed < 20% in a tall PPG wave. 190 datasets were analyzed including 61 episodes of hypertension [SAP = 159 (151-170) mmHg (median 1st-3rd quartiles)], 84 of normotension, SAP = 124 (113-131) mmHg and 45 of hypotension SAP = 85(80-87) mmHg. SAP were well correlated with SVR (r = 0.78, p < 0.0001) and Cvasc (r = 0.84, p < 0.0001). The PPG-based classification correlated well with SAP (r = - 0.90, p < 0.0001), SVR (r = - 0.72, p < 0.0001) and Cvasc (r = 0.82, p < 0.0001). The PPGc misclassified 7 out of the 190 episodes, presenting good accuracy (98.4% and 97.8%), sensitivity (100% and 94.9%) and specificity (97.9% and 99.2%) for detecting episodes of hypotension and hypertension, respectively. Changes in arterial pressure and vascular tone were closely related to the proposed classification based on PPG waveform.Clinical Trial Registration NTC02854852.

Closed-loop vasopressor control: in-silico study of robustness against pharmacodynamic variability

Initial feasibility of a novel closed-loop controller created by our group for closed-loop control of vasopressor infusions has been previously described. In clinical practice, vasopressor potency may be affected by a variety of factors including other pharmacologic agents, organ dysfunction, and vasoplegic states. The purpose of this study was therefore to evaluate the effectiveness of our controller in the face of large variations in drug potency, where 'effective' was defined as convergence on target pressure over time. We hypothesized that the controller would remain effective in the face up to a tenfold variability in drug response. To perform the robustness study, our physiologic simulator was used to create randomized simulated septic patients. 250 simulated patients were managed by the closed-loop in each of 7 norepinephrine responsiveness conditions: 0.1 ×, 0.2 ×, 0.5 ×, 1 ×, 2 ×, 5 ×, and 10 × expected population response to drug dose. Controller performance was evaluated for each level of norepinephrine response using Varvel's criteria as well as time-out-of-target. Median performance error and median absolute performance error were less than 5% in all response levels. Wobble was below 3% and divergence remained negative (i.e. the controller tended to converge towards the target over time) in all norepinephrine response levels, but at the highest response level of 10 × the value approached zero, suggesting the controller may be approaching instability. Response levels of 0.1 × and 0.2 × exhibited significantly higher time-out-of-target in the lower ranges (p < 0.001) compared to the 1 × response level as the controller was slower to correct the initial hypotension. In this simulation study, the closed-loop vasopressor controller remained effective in simulated patients exhibiting 0.1 to 10 × the expected population drug response.

Utility of Geriatric Assessment in the Projection of Early Mortality Following Hip Fracture in the Elderly Patients

Hip fractures result in significant morbidity and mortality in elders. Indicators of frailty are associated with poor outcomes. Commonly used frailty tools rely on motor skills that cannot be performed by this population. We determined the association between the Charlson Comorbidity Score (CCS), intraoperative hypotension (IOH), and a geriatric medicine consult index (GCI) with short-term mortality in hip fracture patients. A retrospective cohort study was conducted at a single institution over a 2-year period. Patients aged 65 years and older who sustained a hip fracture following a low-energy mechanism were identified using billing records and our orthopedic fracture registry. Medical records were reviewed to collect demographic data, fracture classification and operative records, calculation of CCS, intraoperative details including hypotension, and assessments recorded in the geriatric consult notes. The GCI was calculated using 30 dichotomous variables contained within the geriatric consult note. The index, ranging from 0 to 1, included markers for physical and cognitive function, as well as medications. A higher GCI score indicated more markers for frailty. One hundred eight patients met inclusion criteria. Sixty-four (59%) were females and the average age was 77.3 years. Thirty-five (32%) patients sustained femoral neck fractures, and 73 (68%) patients sustained inter-/pertrochanteric hip fractures. The 30-day mortality was 6%; the 90-day mortality was 13%. The mean GCI was 0.30 in the 30-day survivor group as compared to 0.52 in those who died. The mean GCI was 0.28 in patients who were alive at 90 days as compared to 0.46 in those who died. In contrast, the CCS and IOH were not associated with 30- or 90-day mortality. In our older hip fracture patients, an index calculated from information routinely obtained in the geriatric consult evaluation was associated with 30- and 90-day mortality, whereas the CCS and measures of IOH were not.

Peripheral nerve block combined with general anesthesia for lower extremity amputation in hemodialysis patients: case series

Background

Anesthetic management of lower extremity amputation in chronic hemodialysis (HD) patients can be challenging because of their poor cardiovascular status. As previously reported, peripheral nerve block (PNB) may be beneficial in these complicated cases. We report the effects of PNB combined with general anesthesia on hemodynamic stability in HD patients undergoing elective lower extremity amputation.

Methods

We retrospectively analyzed 13 HD patients who underwent lower extremity amputation. Patients received general anesthesia (GA group, n = 7) or general anesthesia combined with PNB (GA with PNB group, n = 6), as decided by the anesthesiologists. Mean blood pressure (MBP), systolic blood pressure (SBP), lowest BP, heart rate (HR), blood loss, fluid and blood infusion volumes, and doses of vasopressors required were compared for hemodynamic assessment. The coefficient of variation (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \mathrm{CV}=\upsigma /\overline{\mathcal{X}} $$\end{document}CV=σ/X¯) of MBP (CV_MBP) and SBP (CV_SBP) was calculated to compare hemodynamic stability. Intraoperative opioid use and postoperative pain scores at rest using a numerical rating scale (NRS) on postoperative days 0 and 1 were compared for pain assessment. We also assessed 30-day mortality.

Results

CV_MBP in the GA group was significantly higher than that in the GA with PNB group (0.15 ± 0.05 and 0.08 ± 0.04, respectively, p = 0.03). The CV_SBP in the GA group was also significantly higher than that in the GA with PNB group (0.16 ± 0.02 and 0.09 ± 0.01, respectively, p = 0.03). No significant differences in other hemodynamic parameters were observed. Intraoperative fentanyl doses were significantly lower in the GA with PNB group (GA 210.7 ± 99.9 μg vs. GA with PNB 113.0 ± 75.6 μg, p = 0.04). There were no significant differences in other pain parameters and 30-day mortality between the groups.

Conclusion

Our results suggest that PNB combined with general anesthesia contributes to intraoperative hemodynamic stability through better pain control in HD patients undergoing lower extremity amputation.

Safety of sedation for gastrointestinal endoscopy in a group of university-affiliated hospitals: a prospective cohort study

BACKGROUND

Service models for gastrointestinal endoscopy sedation must be safe, as endoscopy is the most common procedure performed under sedation in many countries. The aim of this prospective cohort study was to determine the patient risk profile, and incidence of and risk factors for significant unplanned events, in adult patients presenting for gastrointestinal endoscopy in a group of university-affiliated hospitals where most sedation is managed by anaesthetists.

METHODS

Patients aged ≥18 yr presenting for elective and emergency gastrointestinal endoscopy under anaesthetist-managed sedation at nine hospitals affiliated with the University of Melbourne, Australia, were included. Outcomes included significant airway obstruction, hypoxia, hypotension and bradycardia; unplanned tracheal intubation; abandoned procedure; advanced life support; prolonged post-procedure stay; unplanned over-night admission and 30-day mortality.

RESULTS

2,132 patients were included. Fifty percent of patients were aged >60 yr, 50% had a BMI >27 kg m ^-2, 42% were ASA physical status III-V and 17% were emergency patients. The incidence of significant unplanned events was 23.0% (including significant hypotension 11.8%). Significant unplanned intraoperative events were associated with increasing age, BMI <18.5 kg m ^-2, ASA physical status III-V, colonoscopy and planned tracheal intubation. Thirty-day mortality was 1.2% (0.2% in electives and 6.0% in emergencies) and was associated with ASA physical status IV-V and emergency status.

CONCLUSIONS

Patients presenting for gastrointestinal endoscopy at a group of public university-affiliated hospitals where most sedation is managed by anaesthetists, had a high risk profile and a substantial incidence of significant unplanned intraoperative events and 30-day mortality.

Pre-operative fluid bolus for improved haemodynamic stability during minor surgery: A prospectively randomized clinical trial

BACKGROUND

Haemodynamic instability during the induction of anaesthesia and surgery is common and may be related to hypovolaemia caused by pre-operative fasting or chronic diuretic therapy. The aim of our prospective, controlled, randomized study was to test the hypothesis that a predefined fluid bolus given prior to general anaesthesia for minor surgery would increase haemodynamic stability during anaesthetic induction.

METHODS

Two hundred and nineteen fairly healthy adult patients requiring minor surgery were enrolled. All received standard treatment, including a pulse contour analysing device for non-invasive measurement of cardiac index. Infusion therapy was started in all patients at induction. The intervention group (106 patients) was randomized to receive an additional fluid bolus of 8 mL/kg Ringer's acetate solution before the induction of anaesthesia. The primary endpoint was the incidence of haemodynamic instability, defined as a significant reduction of blood pressure or cardiac index during induction of anaesthesia.

RESULTS

The interventional group had a lesser incidence of haemodynamic instability during induction (41.5% vs 56.6%, P = .025). This group also had higher cardiac index, stroke volume index, systolic and mean blood pressure and a greater left ventricular end-diastolic area.

CONCLUSIONS

A fluid bolus prior to anaesthesia reduced the incidence of haemodynamic instability during induction of general anaesthesia. The total fluid volume was slightly greater in the intervention group compared to the control group (1370 ± 439 mL vs 1219 ± 483 mL, P = .007). We conclude that a defined fluid bolus can help stabilizing haemodynamics in patients undergoing general anaesthesia.

Supervised Machine-learning Predictive Analytics for Prediction of Postinduction Hypotension

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Hypotension is a risk factor for adverse perioperative outcomes. Machine-learning methods allow large amounts of data for development of robust predictive analytics. The authors hypothesized that machine-learning methods can provide prediction for the risk of postinduction hypotension.

Methods

Data was extracted from the electronic health record of a single quaternary care center from November 2015 to May 2016 for patients over age 12 that underwent general anesthesia, without procedure exclusions. Multiple supervised machine-learning classification techniques were attempted, with postinduction hypotension (mean arterial pressure less than 55 mmHg within 10 min of induction by any measurement) as primary outcome, and preoperative medications, medical comorbidities, induction medications, and intraoperative vital signs as features. Discrimination was assessed using cross-validated area under the receiver operating characteristic curve. The best performing model was tuned and final performance assessed using split-set validation.

Results

Out of 13,323 cases, 1,185 (8.9%) experienced postinduction hypotension. Area under the receiver operating characteristic curve using logistic regression was 0.71 (95% CI, 0.70 to 0.72), support vector machines was 0.63 (95% CI, 0.58 to 0.60), naive Bayes was 0.69 (95% CI, 0.67 to 0.69), k-nearest neighbor was 0.64 (95% CI, 0.63 to 0.65), linear discriminant analysis was 0.72 (95% CI, 0.71 to 0.73), random forest was 0.74 (95% CI, 0.73 to 0.75), neural nets 0.71 (95% CI, 0.69 to 0.71), and gradient boosting machine 0.76 (95% CI, 0.75 to 0.77). Test set area for the gradient boosting machine was 0.74 (95% CI, 0.72 to 0.77).

Conclusions

The success of this technique in predicting postinduction hypotension demonstrates feasibility of machine-learning models for predictive analytics in the field of anesthesiology, with performance dependent on model selection and appropriate tuning.

New antihypertensive medications and clinical implications

Hypertension remains a global public health issue and is a leading preventable risk factor for many causes of mortality and morbidity. Although it is generally managed as an outpatient chronic disease, anaesthetists will inevitably encounter patients with hypertension, ranging from undiagnosed asymptomatic to chronic forms with end-organ damage(s). An understanding of perioperative management of anti-hypertensive pharmacotherapy is crucial. Although many drugs are familiar, new drug groups that have relevance for blood pressure control and perioperative care have evolved in recent years. This article also describes new antihypertensive agents currently available or under development that could impact perioperative management.

Intraoperative hypotension and the risk of postoperative adverse outcomes: a systematic review

BACKGROUND

Intraoperative hypotension is a common side effect of general anaesthesia and might lead to inadequate organ perfusion. It is unclear to what extent hypotension during noncardiac surgery is associated with unfavourable outcomes.

METHODS

We conducted a systematic search in PubMed, Embase, Web of Science, and CINAHL, and classified the quality of retrieved articles according to predefined adapted STROBE and CONSORT criteria. Reported strengths of associations from high-quality studies were classified into end-organ specific injury risks, such as acute kidney injury, myocardial injury, and stroke, and overall organ injury risks for various arterial blood pressure thresholds.

RESULTS

We present an overview of 42 articles on reported associations between various absolute and relative intraoperative hypotension definitions and their associations with postoperative adverse outcomes after noncardiac surgery. Elevated risks of end-organ injury were reported for prolonged exposure (≥10 min) to mean arterial pressures <80 mm Hg and for shorter durations <70 mm Hg. Reported risks increase with increased durations for mean arterial pressures <65-60 mm Hg or for any exposure <55-50 mm Hg.

CONCLUSIONS

The reported associations suggest that organ injury might occur when mean arterial pressure decreases <80 mm Hg for ≥10 min, and that this risk increases with blood pressures becoming progressively lower. Given the retrospective observational design of the studies reviewed, reflected by large variability in patient characteristics, hypotension definitions and outcomes, solid conclusions on which blood pressures under which circumstances are truly too low cannot be drawn. We provide recommendations for the design of future studies. CLINICAL REGISTRATION NUMBER: (PROSPERO ID). CRD42013005171.

Perioperative myocardial injury and the contribution of hypotension

Mortality in the month following surgery is about 1000 times greater than anesthesia-related intraoperative mortality, and myocardial injury appears to be the leading cause. There is currently no known safe prophylaxis for postoperative myocardial injury, but there are strong associations among hypotension and myocardial injury, renal injury, and death. During surgery, the harm threshold is a mean arterial pressure of about 65 mmHg. In critical care units, the threshold appears to be considerably greater, perhaps 90 mmHg. The threshold triggering injury on surgical wards remains unclear but may be in between. Much of the association between hypotension and serious complications surely results from residual confounding, but sparse randomized data suggest that at least some harm can be prevented by intervening to limit hypotension. Reducing hypotension may therefore improve perioperative outcomes.

Design of a Novel Multifunction Decision Support Display for Anesthesia Care: AlertWatch® OR

BACKGROUND

This paper describes the design of a multifunction alerting display for intraoperative anesthetic care. The design was inspired by the multifunction primary flight display used in modern aviation.

RESULTS

The display retrieves live data from multiple sources; the physiologic monitors, the anesthesia information management system, the laboratory values and comorbidities from patient's problem summary list, medical history or history & physical. This information is integrated into a display composed of readily identifiable icons of organ systems, which are color coded to signify normal range, marginal range, abnormal range (by green, yellow, red respectively) and orange outlines for comorbidities/risk factors. There are dozens of text alerts, which can be presented as black text (informational), red text (important information) and red scrolling text (highest importance information). The alerts are derived from current standards in the literature and some involve complex calculations being conducted in the background.

CONCLUSIONS

The goal of such a system is to improve the quality and safety of anesthetic care by providing enhanced situational awareness in a fashion analogous to the "glass cockpit" and its primary flight display which has improved aviation safety.

Beat-by-beat assessment of cardiac afterload using descending aortic velocity-pressure loop during general anesthesia: a pilot study

INTRODUCTION

Continuous cardiac afterload evaluation could represent a useful tool during general anesthesia (GA) to titrate vasopressor effect. Using beat to beat descending aortic pressure(P)/flow velocity(U) loop obtained from esophageal Doppler and femoral pressure signals might allow to track afterload changes. Methods We defined three angles characterizing the PU loop (alpha, beta and Global After-Load Angle (GALA)). Augmentation index (AIx) and total arterial compliance (Ctot) were measured via radial tonometry. Peripheral Vascular Resistances (PVR) were also calculated. Twenty patients were recruited and classified into low and high cardiovascular (CV) risk group. Vasopressors were administered, when baseline mean arterial pressure (MAP) fell by 20%. Results We studied 118 pairs of pre/post bolus measurements. At baseline, patients in the lower CV risk group had higher cardiac output (6.1 ± 1.7 vs 4.2 ± 0.6 L min; p = 0.005), higher Ctot (2.7 ± 1.0 vs 2.0 ± 0.4 ml/mmHg, p = 0.033), lower AIx and PVR (13 ± 10 vs 32 ± 11% and 1011 ± 318 vs 1390 ± 327 dyn s/cm5; p < 0.001 and p = 0.016, respectively) and lower GALA (41 ± 15 vs 68 ± 6°; p < 0.001). GALA was the only PU Loop parameter associated with Ctot, AIx and PVR. After vasopressors, MAP increase was associated with a decrease in Ctot, an increase in AIx and PVR and an increase in alpha, beta and GALA (p < 0.001 for all). Changes in GALA and Ctot after vasopressors were strongly associated (p = 0.004). Conclusions PU Loop assessment from routine invasive hemodynamic optimization management during GA and especially GALA parameter could monitor cardiac afterload continuously in anesthetized patients, and may help clinicians to titrate vasopressor therapy.

Impact of a Novel Multiparameter Decision Support System on Intraoperative Processes of Care and Postoperative Outcomes

Background

The authors hypothesized that a multiparameter intraoperative decision support system with real-time visualizations may improve processes of care and outcomes.

Methods

Electronic health record data were retrospectively compared over a 6-yr period across three groups: experimental cases, in which the decision support system was used for 75% or more of the case at sole discretion of the providers; parallel controls (system used 74% or less); and historical controls before system implementation. Inclusion criteria were adults under general anesthesia, advanced medical disease, case duration of 60 min or longer, and length of stay of two days or more. The process measures were avoidance of intraoperative hypotension, ventilator tidal volume greater than 10 ml/kg, and crystalloid administration (ml · kg–1 · h–1). The secondary outcome measures were myocardial injury, acute kidney injury, mortality, length of hospital stay, and encounter charges.

Results

A total of 26,769 patients were evaluated: 7,954 experimental cases, 10,933 parallel controls, and 7,882 historical controls. Comparing experimental cases to parallel controls with propensity score adjustment, the data demonstrated the following medians, interquartile ranges, and effect sizes: hypotension 1 (0 to 5) versus 1 (0 to 5) min, P &lt; 0.001, beta = –0.19; crystalloid administration 5.88 ml · kg–1 · h–1 (4.18 to 8.18) versus 6.17 (4.32 to 8.79), P &lt; 0.001, beta = –0.03; tidal volume greater than 10 ml/kg 28% versus 37%, P &lt; 0.001, adjusted odds ratio 0.65 (0.53 to 0.80); encounter charges $65,770 ($41,237 to $123,869) versus $69,373 ($42,101 to $132,817), P &lt; 0.001, beta = –0.003. The secondary clinical outcome measures were not significantly affected.

Conclusions

The use of an intraoperative decision support system was associated with improved process measures, but not postoperative clinical outcomes.

Techniques for Non-Invasive Monitoring of Arterial Blood Pressure

Since both, hypotension and hypertension, can potentially impair the function of vital organs such as heart, brain, or kidneys, monitoring of arterial blood pressure (BP) is a mainstay of hemodynamic monitoring in acutely or critically ill patients. Arterial BP can either be obtained invasively via an arterial catheter or non-invasively. Non-invasive BP measurement provides either intermittent or continuous readings. Most commonly, an occluding upper arm cuff is used for intermittent non-invasive monitoring. BP values are then obtained either manually (by auscultation of Korotkoff sounds or palpation) or automatically (e.g., by oscillometry). For continuous non-invasive BP monitoring, the volume clamp method or arterial applanation tonometry can be used. Both techniques enable the arterial waveform and BP values to be obtained continuously. This article describes the different techniques for non-invasive BP measurement, their advantages and limitations, and their clinical applicability.

Comparison of the effect of high versus low mean arterial pressure levels on clinical outcomes and complications in elderly patients during non-cardiothoracic surgery under general anesthesia: study protocol for a randomized controlled trial

BACKGROUND

Intraoperative blood pressure (BP) is a concern in daily clinic anesthesia and contributes to the differences in clinical outcome. We conducted a randomized controlled trial (RCT) to compare the effect of high vs. low mean arterial pressure (MAP) levels on clinical outcomes and complications in elderly patients under general anesthesia (GA).

METHODS

In this multicenter, randomized, parallel-controlled, open-label, assessor-blinded clinical trial, 322 patients aged more than 65 years will be randomized for a low-level MAP (60-70 mmHg) or high-level MAP (90-100 mmHg) during non-cardiothoracic surgery under GA. The primary outcome will be the incidence of postoperative delirium. The secondary outcomes will include the delirium duration days, intraoperative urine volume, intraoperative blood loss, specific postoperative complications, and all-cause 28-day mortality.

DISCUSSION

Results of this trial will help clarify whether BP management is beneficial for elderly patients under GA and will make clear whether the effect of high-level MAP can reduce the postoperative complication compared to low-level MAP.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02857153 . Registered on 15 July 2016.

Effect of Individualized vs Standard Blood Pressure Management Strategies on Postoperative Organ Dysfunction Among High-Risk Patients Undergoing Major Surgery: A Randomized Clinical Trial

IMPORTANCE

Perioperative hypotension is associated with an increase in postoperative morbidity and mortality, but the appropriate management strategy remains uncertain.

OBJECTIVE

To evaluate whether an individualized blood pressure management strategy tailored to individual patient physiology could reduce postoperative organ dysfunction.

DESIGN, SETTING, AND PARTICIPANTS

The Intraoperative Norepinephrine to Control Arterial Pressure (INPRESS) study was a multicenter, randomized, parallel-group clinical trial conducted in 9 French university and nonuniversity hospitals. Adult patients (n = 298) at increased risk of postoperative complications with a preoperative acute kidney injury risk index of class III or higher (indicating moderate to high risk of postoperative kidney injury) undergoing major surgery lasting 2 hours or longer under general anesthesia were enrolled from December 4, 2012, through August 28, 2016 (last follow-up, September 28, 2016).

INTERVENTIONS

Individualized management strategy aimed at achieving a systolic blood pressure (SBP) within 10% of the reference value (ie, patient's resting SBP) or standard management strategy of treating SBP less than 80 mm Hg or lower than 40% from the reference value during and for 4 hours following surgery.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of systemic inflammatory response syndrome and dysfunction of at least 1 organ system of the renal, respiratory, cardiovascular, coagulation, and neurologic systems by day 7 after surgery. Secondary outcomes included the individual components of the primary outcome, durations of ICU and hospital stay, adverse events, and all-cause mortality at 30 days after surgery.

RESULTS

Among 298 patients who were randomized, 292 patients completed the trial (mean [SD] age, 70 [7] years; 44 [15.1%] women) and were included in the modified intention-to-treat analysis. The primary outcome event occurred in 56 of 147 patients (38.1%) assigned to the individualized treatment strategy vs 75 of 145 patients (51.7%) assigned to the standard treatment strategy (relative risk, 0.73; 95% CI, 0.56 to 0.94; P = .02; absolute risk difference, -14%, 95% CI, -25% to -2%). Sixty-eight patients (46.3%) in the individualized treatment group and 92 (63.4%) in the standard treatment group had postoperative organ dysfunction by day 30 (adjusted hazard ratio, 0.66; 95% CI, 0.52 to 0.84; P = .001). There were no significant between-group differences in severe adverse events or 30-day mortality.

CONCLUSIONS AND RELEVANCE

Among patients predominantly undergoing abdominal surgery who were at increased postoperative risk, management targeting an individualized systolic blood pressure, compared with standard management, reduced the risk of postoperative organ dysfunction.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01536470.