High-Target Versus Low-Target Blood Pressure Management During Cardiopulmonary Bypass to Prevent Cerebral Injury in Cardiac Surgery Patients: A Randomized Controlled Trial

Impact of cardiopulmonary bypass flow on the lower limit of cerebral autoregulation during cardiac surgery: a randomized cross-over pilot study

Assessment of cerebral autoregulation is challenging under different hemodynamic conditions during cardiac surgery and must be rapidly calculated in order to optimize mean arterial pressure (MAP). Whether systemic flow during cardiopulmonary bypass impacts the lower limit of cerebral autoregulation (LLA) remains unclear. Forty patients requiring cardiac surgery were included in this randomized crossover study. Patients assigned to the conventional/high blood flow arm received 20 min of conventional cardiopulmonary bypass (CPB) blood flow (2.2 L/min.m-²) followed by 20 min of high blood flow (2.8 L/min.m-²), both during aortic cross clamping. Patients assigned to the high/conventional arm received the same flows but in reverse order. During each 20-minute period, MAP was gradually increased from 40 to 90 mmHg, while PaCO2, hematocrit, depth of anesthesia, central temperature and arterial oxygen tension were kept constant. Continuous cerebral blood flow velocities of the middle cerebral artery (Fv) were monitored using transcranial doppler. Cerebral autoregulation was calculated using a Pearson's correlation coefficient (Mean flow index, Mxa) between the MAP and Fv. Mxa values were then plotted across MAP ranges. The LLA was defined as the corresponding MAP value when Mxa initially decreased and crossed the threshold value of 0.4. A mixed model, including the LLA as the dependent variable, the CPB flow and period as fixed effects and patients as a random effect was used to compare conventional and high CPB flows. Thirty-seven patients were analyzed. The LLA mean difference between groups, adjusted on the period, was - 2.8 (SE 2.4) mmHg with 95% CI [-7.8, + 2.1 mmHg], p = 0.2538). 24% of patients presented an LLA < 65 mmHg during the conventional CPB flow phase versus 35% during the high CPB flow phase. Increasing the cardiopulmonary pump flow did not decrease the LLA during cardiac surgery.

2024 EACTS/EACTAIC/EBCP Guidelines on cardiopulmonary bypass in adult cardiac surgery

Clinical practice guidelines consolidate and evaluate all pertinent evidence on a specific topic available at the time of their formulation. The goal is to assist physicians in determining the most effective management strategies for patients with a particular condition. These guidelines assess the impact on patient outcomes and weigh the risk-benefit ratio of various diagnostic or therapeutic approaches. While not a replacement for textbooks, they provide supplementary information on topics relevant to current clinical practice and become an essential tool to support the decisions made by specialists in daily practice. Nonetheless, it is crucial to understand that these recommendations are intended to guide, not dictate, clinical practice, and should be adapted to each patient's unique needs. Clinical situations vary, presenting a diverse array of variables and circumstances. Thus, the guidelines are meant to inform, not replace, the clinical judgement of healthcare professionals, grounded in their professional knowledge, experience and comprehension of each patient's specific context. Moreover, these guidelines are not considered legally binding; the legal duties of healthcare professionals are defined by prevailing laws and regulations, and adherence to these guidelines does not modify such responsibilities. The European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Cardiothoracic Anaesthesiology and Intensive Care (EACTAIC) and the European Board of Cardiovascular Perfusion (EBCP) constituted a task force of professionals specializing in cardiopulmonary bypass (CPB) management. To ensure transparency and integrity, all task force members involved in the development and review of these guidelines submitted conflict of interest declarations, which were compiled into a single document available on the EACTS website (https://www.eacts.org/resources/clinical-guidelines). Any alterations to these declarations during the development process were promptly reported to the EACTS, EACTAIC and EBCP. Funding for this task force was provided exclusively by the EACTS, EACTAIC and EBCP, without involvement from the healthcare industry or other entities. Following this collaborative endeavour, the governing bodies of EACTS, EACTAIC and EBCP oversaw the formulation, refinement, and endorsement of these extensively revised guidelines. An external panel of experts thoroughly reviewed the initial draft, and their input guided subsequent amendments. After this detailed revision process, the final document was ratified by all task force experts and the leadership of the EACTS, EACTAIC and EBCP, enabling its publication in the European Journal of Cardio-Thoracic Surgery, the British Journal of Anaesthesia and Interdisciplinary CardioVascular and Thoracic Surgery. Endorsed by the EACTS, EACTAIC and EBCP, these guidelines represent the official standpoint on this subject. They demonstrate a dedication to continual enhancement, with routine updates planned to ensure that the guidelines remain current and valuable in the ever-progressing arena of clinical practice.

Analysis of influencing factors for postoperative brain injury in patients with cardiac surgery

OBJECTIVE

To identify risk factors in people with heart disease prior to undergoing cardiac surgery and to provide a prediction model.

METHODS

106 patients who underwent cardiac surgery were selected by convenience sampling method. Case-control study design was used to divide them into control and observation groups according to whether there was postoperative brain injury. General demographic data, perioperative surgery, postoperative recovery, past medical history and preoperative conditions, laboratory test indicators were collected. Univariate and multivariate Logistic regression analyses were performed to select influencing factors. A nomogram model for predicting postoperative brain injury was established.

RESULTS

Univariate Logistic regression analysis showed that age, female, stroke, diabetes mellitus, perioperative administration of dexmedetomidine, intraoperative use of cardiopulmonary bypass were related factors for postoperative brain injury(p < 0.05). Multivariate Logistic regression analysis showed that females, history of stroke, and intraoperative use of cardiopulmonary bypass were risk factors, and perioperative administration of dexmedetomidine was protective factor(p < 0.05). Nomogram model was established with an AUC of 0.847 and accuracy of 84.7%.

CONCLUSION

Preoperative stroke history and females are risk factors for brain injury after coronary artery bypass grafting under cardiopulmonary bypass, and perioperative use of dexmedetomidine is protective factor.

Prebypass Critical Closing Pressure Predicts Acute Kidney Injury After Cardiopulmonary Bypass

OBJECTIVES

Optimal blood pressure goals during cardiopulmonary bypass (CPB) remain uncertain and new metrics to individualize perfusion targets are needed. Critical closing pressure (Pcrit) is a fundamental property of the arterial circulation related to vascular tone and represents the outflow pressure impacting flow across the systemic circulation. We examined Pcrit as a prognostic marker of acute kidney injury (AKI).

DESIGN

Retrospective cohort study.

SETTING

Single tertiary care hospital PARTICIPANTS: We included 1,038 adult cardiac surgery patients who underwent CPB.

INTERVENTIONS

Pcrit was calculated using arterial waveform data before initiation of CPB. Pcrit was examined in relation to incidence of stage 2 or higher postoperative AKI according to standard Kidney Disease Improving Global Outcomes definitions.

MEASUREMENTS AND MAIN RESULTS

Of the 1,038 patients included in the study, 50 (5%) experienced AKI. Patients who suffered AKI had significantly higher preoperative risk factors, including higher incidence of severe chronic kidney disease and higher Society of Thoracic Surgeons risk score (p < 0.01). They also had longer operative times and longer cross-clamp times (p < 0.01). All patients were maintained at similar mean arterial pressure while on CPB. Patients who suffered AKI had a significantly higher prebypass Pcrit than those who did not (49.0 mmHg vs 44.1 mmHg; p = 0.018). In a multivariate regression, Pcrit remained a significant predictor, representing a 16% increased risk of AKI for each 5 mmHg increase in prebypass Pcrit (p = 0.011).

CONCLUSIONS

A higher prebypass Pcrit is associated with a significantly higher incidence of postoperative AKI. Future study is warranted to investigate using intraoperative Pcrit to determine a personalized blood pressure goal during CPB.

Effects of noradrenaline and phenylephrine on cerebral oxygen saturation during cardiopulmonary bypass in cardiac surgery

Cardiopulmonary bypass (CPB) in cardiac surgery is associated with a high risk of postoperative neurological complications. Perioperative use of vasopressors is common to counteract arterial hypotension in this setting. However, use of α-agonist vasopressors has been associated with cerebral desaturations. Given that reductions in cerebral oxygen saturation (S c O 2 ${S_{{\mathrm{c}}{{\mathrm{O}}_2}}}$ ) can increase postoperative neurological dysfunction, we aimed to investigate the impact of noradrenaline (NA) and phenylephrine (PE) onS c O 2 ${S_{{\mathrm{c}}{{\mathrm{O}}_2}}}$ during the CPB period of a cardiac surgery in 36 patients scheduled for an elective cardiac surgery. Patients were randomized to the intra-operative use of either NA or PE. During CPB, mean arterial pressure (MAP) was elevated pharmacologically to predefined thresholds of 60 and 80 mmHg, while CPB flow was kept constant. TheS c O 2 ${S_{{\mathrm{c}}{{\mathrm{O}}_2}}}$ values were recorded for 5 min per MAP threshold. The MAP increased adequately between thresholds of 60 and 80 mmHg (NA, 59 ± 3 vs. 81 ± 3 mmHg and PE, 61 ± 4 vs. 81 ± 3 mmHg; P ˂ 0.01). TheS c O 2 ${S_{{\mathrm{c}}{{\mathrm{O}}_2}}}$ decreased between pressure thresholds of 60 and 80 mmHg (NA, 70 ± 11 vs. 69 ± 11 mmHg and PE, 64 ± 11 vs. 63 ± 11 mmHg; P ˂ 0.01). Reduction inS c O 2 ${S_{{\mathrm{c}}{{\mathrm{O}}_2}}}$ did not differ between vasopressors. The mean relative decrease inS c O 2 ${S_{{\mathrm{c}}{{\mathrm{O}}_2}}}$ across groups was 2.0% (95% confidence interval: 0.6 to 2.1). Elevation in MAP mediated solely by vasopressors induces significant decreases inS c O 2 ${S_{{\mathrm{c}}{{\mathrm{O}}_2}}}$ during cardiac surgery under CPB. However, their impact onS c O 2 ${S_{{\mathrm{c}}{{\mathrm{O}}_2}}}$ remains clinically non-significant according to current guidelines.

Intraoperative high and low blood pressures are not associated with delirium after cardiac surgery: A retrospective cohort study

STUDY OBJECTIVE

To evaluate the associations between high and low intraoperative time-weighted average mean arterial pressures before, during and after cardiopulmonary bypass on postoperative delirium.

DESIGN

Single center retrospective cohort study.

SETTING

Operating rooms and postoperative care units.

PATIENTS

11,382 patients, 18 years of age or older who had cardiac surgery requiring cardiopulmonary bypass between January 2017 and December 2020 at the Cleveland Clinic Main Campus.

INTERVENTIONS

All cardiac surgery requiring bypass except procedures requiring deep hypothermic circulatory arrest.

MEASUREMENTS

Post operative delirium was assessed from 12 to 96 h postoperatively, using the Confusion Assessment Method and brief Confusion Assessment Methods. Hypotension and hypertension were defined as time-weighted average mean arterial pressure < 60 and > 80 mmHg.

MAIN RESULTS

Postoperative delirium occurred in 678 (6.0 %) of 11,382 patients. Confounder-adjusted associations, using multivariable logistic regression models, between hypotension (time-weighted average mean arterial pressure < 60 mmHg) and hypertension (time-weighted average mean arterial pressure > 80 mmHg) and postoperative delirium were not statistically significant or clinically meaningful before, during, or after the cardiopulmonary bypass.

CONCLUSIONS

This large single-center cohort analysis found no evidence that exposure to high or low blood pressures during various intraoperative phases of cardiac surgery are associated with postoperative delirium.

The association between intraoperative cardiopulmonary bypass power and complications after cardiac surgery

BACKGROUND

Low cardiac power (product of flow and pressure) has been shown to be associated with mortality in patients with cardiogenic shock after acute myocardial infarction, but has not been studied in cardiac surgical patients. This study's hypothesis was that cardiac power during cardiopulmonary bypass for cardiac surgery would have a greater association with adverse events than either flow or MAP (mean arterial pressure) alone.

METHODS

We undertook a retrospective observational study using patient data from February 2015 to March 2022 undergoing cardiac surgery at Fiona Stanley Hospital in Perth Australia. Excluded were patient age less than 18 years old, patients undergoing thoracic transplantation, ventricular assist devices, off pump cardiac surgery and aortic surgery. The primary outcome was a composite outcome of 30-days mortality, stroke or new-onset renal insufficiency.

RESULTS

Overall, 1984 cardiac surgeries were included in the analysis. Neither duration nor area below thresholds tested for power, MAP or flow was associated with the primary composite outcome. However, we found that an area below MAP thresholds 35-50 mmHg was associated with new renal insufficiency (adjusted odds ratio 1.17 [95% CI 1.02 to 1.35] for patients spending 10 min at 10 mmHg below 50 mmHg MAP compared to those who did not).

CONCLUSIONS

This study suggests that MAP during cardiopulmonary bypass, but not power or flow, was an independent risk factor for adverse renal outcomes for cardiac surgical patients.

Comparison of 4% Albumin and Ringer's Acetate on Hemodynamics in On-pump Cardiac Surgery: An Exploratory Analysis of a Randomized Clinical Trial

OBJECTIVES

Compare hemodynamics between 4% albumin and Ringer's acetate.

DESIGN

Exploratory analysis of the double-blind randomized ALBumin In Cardiac Surgery trial.

SETTING

Single-center study in Helsinki University Hospital.

PARTICIPANTS

We included 1,386 on-pump cardiac surgical patients.

INTERVENTION

We used 4% albumin or Ringer's acetate administration for cardiopulmonary bypass priming, volume replacement intraoperatively and 24 hours postoperatively.

MEASUREMENTS AND MAIN RESULTS

Hypotension (time-weighted average mean arterial pressure of <65 mmHg) and hyperlactatemia (time-weighted average blood lactate of >2 mmol/L) incidences were compared between trial groups in the operating room (OR), and early (0-6 hours) and late (6-24 hours) postoperatively. Associations of hypotension and hyperlactatemia with the ALBumin In Cardiac Surgery primary outcome (≥1 major adverse event [MAE]) were studied. In these time intervals, hypotension occurred in 118, 48, and 17 patients, and hyperlactatemia in 313, 131, and 83 patients. Hypotension and hyperlactatemia associated with MAE occurrence. Hypotension did not differ between the groups (albumin vs Ringer's: OR, 8.8% vs 8.5%; early postoperatively, 2.7% vs 4.2%; late postoperatively, 1.2% vs 1.3%; all p > 0.05). In the albumin group, hyperlactatemia was less frequent late postoperatively (2.9% vs 9.1%; p < 0.001), but not earlier (OR, 22.4% vs 23.6%; early postoperatively, 7.9% vs 11.0%; both p > 0.025 after Bonferroni-Holm correction).

CONCLUSIONS

In on-pump cardiac surgery, hypotension and hyperlactatemia are associated with the occurrence of ≥1 MAE. Compared with Ringer's acetate, albumin did not decrease hypotension and decreased hyperlactatemia only late postoperatively. Albumin's modest hemodynamic effect is concordant with the finding of no difference in MAEs between albumin and Ringer's acetate in the ALBumin In Cardiac Surgery trial.

Low Versus High Blood Pressure Targets in Critically Ill and Surgical Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

Hypotension is associated with adverse outcomes in critically ill and perioperative patients. However, these assumptions are supported by observational studies. This meta-analysis of randomized controlled trials aims to compare the impact of lower versus higher blood pressure targets on mortality.

DATA SOURCES

We searched PubMed, Cochrane, and Scholar from inception to February 10, 2024.

STUDY SELECTION

Randomized trials comparing lower versus higher blood pressure targets in the management of critically ill and perioperative settings.

DATA EXTRACTION

The primary outcome was all-cause mortality at the longest follow-up available. This review was registered in the Prospective International Register of Systematic Reviews, CRD42023452928.

DATA SYNTHESIS

Of 2940 studies identified by the search string, 28 (12 in critically ill and 16 in perioperative settings) were included totaling 15,672 patients. Patients in the low blood pressure target group had lower mortality (23 studies included: 1019/7679 [13.3%] vs. 1103/7649 [14.4%]; relative risk 0.93; 95% CI, 0.87-0.99; p = 0.03; I2 = 0%). This corresponded to a 97.4% probability of any increase in mortality with a Bayesian approach. These findings were mainly driven by studies performed in the ICU setting and with treatment lasting more than 24 hours; however, the magnitude and direction of the results were similar in the majority of sensitivity analyses including the analysis restricted to low risk of bias studies. We also observed a lower rate of atrial fibrillation and fewer patients requiring transfusion in low-pressure target groups. No differences were found in the other secondary outcomes.

CONCLUSIONS

Based on pooled randomized trial evidence, a lower compared with a higher blood pressure target results in a reduction of mortality, atrial fibrillation, and transfusion requirements. Lower blood pressure targets may be beneficial but there is ongoing uncertainty. However, the present meta-analysis does not confirm previous findings and recommendations. These results might inform future guidelines and promote the study of the concept of protective hemodynamics.

Prolonged Inotrope Use After Surgery for Congenital Heart Disease: A Common Occurrence with a High Burden of Mortality

Outcomes in patients requiring prolonged inotropes (PI) following surgery for congenital heart disease (CHD) have not been well studied. We aimed to describe the burden of PI use in the immediate postoperative period after CHD surgery and identify risk factors for in-hospital mortality. We conducted a retrospective cohort study using the Pediatric Health Information System® (PHIS) database. Patients 0-18 years with CHD who underwent cardiovascular surgery from 2010 to 2020 were included. Patients who received inotropic medications for > 7 consecutive days after surgery were in the PI group and all others in the control group. Patients who died before 7 days were excluded. Multivariable mixed-effect logistic regression was used to examine risk factors for in-hospital mortality. There were 110,271 patients from 48 centers included, 10,292 in the PI group and 99,979 in the control group. In-hospital mortality was significantly higher in the PI group (24.9% vs. 4.6%, p < 0.001). Ventricular assist device use was rare (1.6%). After adjustment, odds of in-hospital mortality in the PI group was 3.5 (95% CI 3.3-3.8) times higher than in controls. Independent risk factors for in-hospital mortality were age, non-White race, class of CHD, number of complex chronic conditions, preoperative inotrope, preoperative extracorporeal membrane oxygenation, sepsis, stroke, renal failure, number of inotropes at 7 days, and discharge year (p < 0.01 for all). Postoperative PI use in CHD is common and carries a considerable burden of mortality. Additional work is needed to understand which risk factors are modifiable and which patients may benefit from reintervention or advanced heart failure therapies.

Postoperative stroke in acute type A aortic dissection: incidence, outcomes, and perioperative risk factors

BACKGROUND

Despite advances in surgical techniques, the incidence of stroke following acute type A aortic dissection (ATAAD) repair remains markedly high, with substantial immediate and long-term adverse outcomes such as elevated mortality, extended hospital stays, and persistent neurological impairments. The complexity of managing ATAAD extends beyond the operation itself, highlighting a crucial gap in research concerning modifiable preoperative patient conditions and perioperative anesthetic management strategies.

OBJECTIVES

This investigation aimed to elucidate the incidence, consequences, and perioperative determinants of stroke following surgical intervention for acute type A aortic dissection (ATAAD).

METHODS

In a multicenter retrospective analysis, 516 ATAAD surgery patients were evaluated. The data included demographic information, clinical profiles, surgical modalities, and outcomes. The primary endpoint was postoperative stroke incidence, with hospital mortality and other complications serving as secondary endpoints.

RESULTS

Postoperative stroke occurred in 13.6% of patients (70 out of 516) and was associated with significant extension of the ICU (median 10 vs. 5 days, P < 0.001) and hospital stay (median 18 vs. 12 days, P < 0.001). The following key independent stroke risk factors were identified: modified Frailty Index (mFI) ≥ 4 (odds ratio [OR]: 4.18, 95% confidence interval [CI]: 1.24-14.1, P = 0.021), common carotid artery malperfusion (OR: 3.76, 95% CI: 1.23-11.44, P = 0.02), pre-cardiopulmonary bypass (CPB) hypotension (mean arterial pressure ≤ 50 mmHg; OR: 2.17, 95% CI: 1.06-4.44, P = 0.035), ≥ 20% intraoperative decrease in cerebral regional oxygen saturation (rSO2) (OR: 1.93, 95% CI: 1.02-3.64, P = 0.042), and post-CPB vasoactive-inotropic score (VIS) ≥ 10 (OR: 2.24, 95% CI: 1.21-4.14, P = 0.01).

CONCLUSIONS

Postoperative stroke significantly increases ICU and hospital durations in ATAAD surgery patients. These findings highlight the critical need to identify and mitigate major risks, such as high mFI, common carotid artery malperfusion, pre-CPB hypotension, significant cerebral rSO2 reductions, and elevated post-CPB VIS, to improve outcomes and reduce stroke prevalence.

TRIAL REGISTRATION

Thai Clinical Trials Registry (TCTR20230615002). Date registered on June 15, 2023. Retrospectively registered.

The Association of Cerebral Oxygen Desaturation with Postoperative Cognitive Dysfunction in Older Patients: A Review

Postoperative cognitive dysfunction (POCD) is a neurological complication associated with surgery and anesthesia that is commonly observed in older patients, and it can significantly affect patient prognosis and survival. Therefore, predicting and preventing POCD is important. Regional cerebral oxygen saturation (rSO2) reflects cerebral perfusion and oxygenation, and decreased intraoperative cerebral oxygen saturation has been reported to increase the risk of POCD. In this review, we elucidated the important relationship between the decline in rSO2 and risk of POCD in older patients. We also emphasized the importance of monitoring rSO2 during surgery to predict and prevent adverse perioperative cognitive outcomes. The findings reveal that incorporating intraoperative rSO2 monitoring into clinical practice has potential benefits, such as protecting cognitive function, reducing perioperative adverse outcomes, and ultimately improving the overall quality of life of older adults.

Cardiac Surgery-Associated Acute Kidney Injury

AKI is a common and serious complication of cardiac surgery that has a significant impact on patient morbidity and mortality. The Kidney Disease Improving Global Outcomes definition of AKI is widely used to classify and identify AKI associated with cardiac surgery (cardiac surgery-associated AKI [CSA-AKI]) on the basis of changes in serum creatinine and/or urine output. There are various preoperative, intraoperative, and postoperative risk factors for the development of CSA-AKI which should be recognized and addressed as early as possible to expedite its diagnosis, reduce its occurrence, and prevent or ameliorate its devastating complications. Crucial issues are the inaccuracy of serum creatinine as a surrogate parameter of kidney function in the perioperative setting of cardiothoracic surgery and the necessity to discover more representative markers of the pathophysiology of AKI. However, except for the tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 ratio, other diagnostic biomarkers with an acceptable sensitivity and specificity are still lacking. This article provides a comprehensive review of various aspects of CSA-AKI, including pathogenesis, risk factors, diagnosis, biomarkers, classification, prevention, and treatment management.

Differential responses of cerebral and renal oxygenation to altered perfusion conditions during experimental cardiopulmonary bypass in sheep

We tested whether the brain and kidney respond differently to cardiopulmonary bypass (CPB) and to changes in perfusion conditions during CPB. Therefore, in ovine CPB, we assessed regional cerebral oxygen saturation (rSO2 ) by near-infrared spectroscopy and renal cortical and medullary tissue oxygen tension (PO2 ), and, in some protocols, brain tissue PO2 , by phosphorescence lifetime oximetry. During CPB, rSO2 correlated with mixed venous SO2 (r = 0.78) and brain tissue PO2 (r = 0.49) when arterial PO2 was varied. During the first 30 min of CPB, brain tissue PO2 , rSO2 and renal cortical tissue PO2 did not fall, but renal medullary tissue PO2 did. Nevertheless, compared with stable anaesthesia, during stable CPB, rSO2 (66.8 decreasing to 61.3%) and both renal cortical (90.8 decreasing to 43.5 mm Hg) and medullary (44.3 decreasing to 19.2 mm Hg) tissue PO2 were lower. Both rSO2 and renal PO2 increased when pump flow was increased from 60 to 100 mL kg-1  min-1 at a target arterial pressure of 70 mm Hg. They also both increased when pump flow and arterial pressure were increased simultaneously. Neither was significantly altered by partially pulsatile flow. The vasopressor, metaraminol, dose-dependently decreased rSO2 , but increased renal cortical and medullary PO2 . Increasing blood haemoglobin concentration increased rSO2 , but not renal PO2 . We conclude that both the brain and kidney are susceptible to hypoxia during CPB, which can be alleviated by increasing pump flow, even without increasing arterial pressure. However, increasing blood haemoglobin concentration increases brain, but not kidney oxygenation, whereas vasopressor support with metaraminol increases kidney, but not brain oxygenation.

Adverse renal effects associated with cardiopulmonary bypass

Cardiac surgery on cardiopulmonary bypass (CPB) is associated with postoperative renal dysfunction, one of the most common complications of this surgical cohort. Acute kidney injury (AKI) is associated with increased short-term morbidity and mortality and has been the focus of much research. There is increasing recognition of the role of AKI as the key pathophysiological state leading to the disease entities acute and chronic kidney disease (AKD and CKD). In this narrative review, we will consider the epidemiology of renal dysfunction after cardiac surgery on CPB and the clinical manifestations across the spectrum of disease. We will discuss the transition between different states of injury and dysfunction, and, importantly, the relevance to clinicians. The specific facets of kidney injury on extracorporeal circulation will be described and the current evidence evaluated for the use of perfusion-based techniques to reduce the incidence and mitigate the complications of renal dysfunction after cardiac surgery.

Mean Arterial Pressure (MAP) Trial: study protocol for a multicentre, randomized, controlled trial to compare three different strategies of mean arterial pressure management during cardiopulmonary bypass

BACKGROUND

One of the main goals of cardiopulmonary bypass (CPB) is targeting an adequate mean arterial pressure (MAP) during heart surgery, in order to maintain appropriate perfusion pressures in all end-organs. As inheritance of early studies, a value of 50-60 mmHg has been historically accepted as the "gold standard" MAP. However, in the last decades, the CPB management has remarkably changed, thanks to the evolution of technology and the availability of new biomaterials. Therefore, as highlighted by the latest European Guidelines, the current management of CPB can no longer refer to those pioneering studies. To date, only few single-centre studies have compared different strategies of MAP management during CPB, but with contradictory findings and without achieving a real consensus. Therefore, what should be the ideal strategy of MAP management during CPB is still on debate. This trial is the first multicentre, randomized, controlled study which compares three different strategies of MAP management during the CPB.

METHODS

We described herein the methodology of a multicentre, randomized, controlled trial comparing three different approaches to MAP management during CPB in patients undergoing elective cardiac surgery: the historically accepted "standard MAP" (50-60 mmHg), the "high MAP" (70-80 mmHg) and the "patient-tailored MAP" (comparable to the patient's preoperative MAP). It is the aim of the study to find the most suitable management in order to obtain the most adequate perfusion of end-organs during cardiac surgery. For this purpose, the primary endpoint will be the peak of serum lactate (Lmax) released during CPB, as index of tissue hypoxia. The secondary outcomes will include all the intraoperative parameters of tissue oxygenation and major postoperative complications related to organ malperfusion.

DISCUSSION

This trial will assess the best strategy to target the MAP during CPB, thus further improving the outcomes of cardiac surgery.

TRIAL REGISTRATION

NCT05740397 (retrospectively registered; 22/02/2023).

Higher perfusion pressure and pump flow during cardiopulmonary bypass are beneficial for kidney function-a single-centre prospective study

Background: Kidneys play an essential role in the circulatory system, regulating blood pressure and intravascular volume. They are also set on maintaining an adequate filtration pressure in the glomerulus. During the CPB, a decrease in systemic blood pressure and hemoglobin concentration may lead to renal ischemia and subsequent acute kidney injury. Methods: One hundred nine adult patients were prospectively enrolled in this study. The intervention in this study was increasing the flow of the CPB pump to reach the target MAP of > 90 mmHg during the procedure. The control group had a standard pump flow of 2.4 L/min/m2. Results: Standard pump flow of 2.4 L/min/m2 resulted in mean MAP < 90 mmHg during the CPB in most patients in the control group. Maintaining a higher MAP during CPB in this study population did not affect CSA-AKI incidence. However, it increased the intraoperative and postoperative diuresis and decreased renin release associated with CPB. Higher MAP during the CPB did not increase the incidence of cerebrovascular complications after the operation; patients in the highest MAP group had the lowest incidence of postoperative delirium, but the result did not obtain statistical significance. Conclusion: Maintaining MAP > 90 mmHg during the CPB positively impacts intraoperative and postoperative kidney function. It significantly reduces renal hypoperfusion during the procedure compared to MAP < 70 mmHg. MAP > 90 mmHg is safe for the central nervous system, and preliminary results suggest that it may have a beneficial impact on the incidence of postoperative delirium.

Captopril to Lisinopril Conversion in Pediatric Cardiothoracic Surgery Patients Less Than 7 Years of Age (RISE-7)

Hypertension after cardiothoracic surgery is common, often requiring pharmacologic management. The recommended first-line antihypertensives in pediatrics are angiotensin converting enzyme inhibitors. Captopril and enalapril are approved for infants and children; however, lisinopril is only approved for > 7 years of age. This study evaluated safety and efficacy of converting from captopril to lisinopril in patients utilizing a pre-defined conversion of 3 mg captopril to 1 mg lisinopril. This was a single center, retrospective study including patients less than 7 years of age admitted for cardiothoracic surgery who received both captopril and lisinopril from 01/01/2017 to 06/01/2022.The primary outcome was mean change in systolic blood pressure (SBP) from baseline for 72 h after conversion of captopril to lisinopril. A total of 99 patients were enrolled. There was a significant decrease in mean SBP (99.12 mmHg vs 94.86 mmHg; p = 0.007) with no difference in DBP (59.23 mmHg vs 61.95 mmHg; p = 0.07) after conversion to lisinopril. Of the 99 patients who were transitioned to lisinopril, 79 (80%) had controlled SBP, 20 (20%) remained hypertensive, 13 (13%) received an increase in their lisinopril dose, and 2 (2%) required an additional antihypertensive agent. There was a low overall rate of AKI (3%) and hyperkalemia (4%) respectively. This study demonstrates that utilizing lisinopril with a conversion rate of 3 mg of captopril to 1 mg of lisinopril was safe and effective for controlling hypertension in pediatric patients following cardiothoracic surgery.

Perioperative stroke

Ischaemic or haemorrhagic perioperative stroke (that is, stroke occurring during or within 30 days following surgery) can be a devastating complication following surgery. Incidence is reported in the 0.1-0.7% range in adults undergoing non-cardiac and non-neurological surgery, in the 1-5% range in patients undergoing cardiac surgery and in the 1-10% range following neurological surgery. However, higher rates have been reported when patients are actively assessed and in high-risk populations. Prognosis is significantly worse than stroke occurring in the community, with double the 30-day mortality, greater disability and diminished quality of life among survivors. Considering the annual volume of surgeries performed worldwide, perioperative stroke represents a substantial burden. Despite notable differences in aetiology, patient populations and clinical settings, existing clinical recommendations for perioperative stroke are extrapolated mainly from stroke in the community. Perioperative in-hospital stroke is unique with respect to the stroke occurring in other settings, and it is essential to apply evidence from other settings with caution and to identify existing knowledge gaps in order to effectively guide patient care and future research.

Intraoperative Blood Pressure Variability and Early Postoperative Stroke: A Case-Control Study

BACKGROUND

This study aims to assess the association of postoperative stroke with intraoperative hemodynamic variability and transfusion management.

METHODS

In this case-control study, adult patients (≥ 18 years) who had a stroke within 72 hours of a surgical procedure were matched to 2 control patients according to age, sex, and procedure type. Primary risk factors assessed were intraoperative fluid administration, blood product transfusion, vasopressor use, and measures of variability in systolic and diastolic blood pressure and heart rate: maximum, minimum, range, SD, and average real variability. The variables were analyzed with conditional logistic regression, which accounted for the 1:2 matched case-control study design.

RESULTS

Among 687 581 procedures, we identified 64 postoperative strokes (incidence, 9.3 [95% CI, 7.2-11.9] strokes per 100 000 procedures). These cases were matched with 128 controls. Stroke cases had higher Charlson cmorbidity index scores than did controls (P = .046). Blood pressure and heart rate variability measures were not associated with stroke. The risk of stroke was increased with red blood cell (RBC) transfusion (odds ratio [OR], 14.82; 95% CI, 3.40-64.66; P < .001), vasopressor use (OR, 3.91; 95% CI, 1.59-9.60; P = .003), and longer procedure duration (OR, 1.23/h; 95% CI, 1.01-1.51; P = .04). Multivariable analysis of procedure duration, RBC transfusion, and vasopressor use showed that only RBC transfusion was independently associated with an increased risk of stroke (OR, 10.10; 95% CI, 2.14-47.72; P = .004).

CONCLUSIONS

Blood pressure variability was not associated with an increased risk of postoperative stroke; however, RBC transfusion was an independent risk factor.

Acute Kidney Injury after Cardiac Surgery: Prediction, Prevention, and Management

Acute kidney injury (AKI) is a common complication in cardiac surgery patients, with a reported incidence of 20 to 30%. The development of AKI is associated with worse short- and long-term mortality, and longer hospital length of stay. The pathogenesis of cardiac surgery-associated AKI is poorly understood but likely involves an interplay between preoperative comorbidities and perioperative stressors. AKI is commonly diagnosed by using increases in serum creatinine or decreased urine output and staged using a standardized definition such as the Kidney Disease Improving Global Outcomes classification. Novel biomarkers under investigation may provide earlier detection and better prediction of AKI, enabling mitigating therapies early in the perioperative period. Recent clinical trials of cardiac surgery patients have demonstrated the benefit of goal-directed oxygen delivery, avoidance of hyperthermic perfusion and specific fluid and medication strategies. This review article highlights both advances and limitations regarding the prevention, prediction, and treatment of cardiac surgery-associated AKI.

Neurologic complications after cardiopulmonary bypass - A narrative review

Neurologic complications, associated with cardiac surgery and cardiopulmonary bypass (CPB) in adults, are common and can be devastating in some cases. This comprehensive review will not only consider the broad categories of stroke and neurocognitive dysfunction, but it also summarises other neurological complications associated with CPB, and it provides an update about risks, prevention and treatment. Where appropriate, we consider the impact of off-pump techniques upon our understanding of the contribution of CPB to adverse outcomes.

Alterations to Kidney Physiology during Cardiopulmonary Bypass-A Narrative Review of the Literature and Practical Remarks

INTRODUCTION

According to different authors, cardiac surgery-associated acute kidney injury (CSA-AKI) incidence can be as high as 20-50%. This complication increases postoperative morbidity and mortality and impairs long-term kidney function in some patients. This review aims to summarize current knowledge regarding alterations to renal physiology during cardiopulmonary bypass (CPB) and to discuss possible nephroprotective strategies for cardiac surgeries. Relevant sections: Systemic and renal circulation, Vasoactive drugs, Fluid balance and Osmotic regulation and Inflammatory response.

CONCLUSIONS

Considering the available scientific evidence, it is concluded that adequate kidney perfusion and fluid balance are the most critical factors determining postoperative kidney function. By adequate perfusion, one should understand perfusion with proper oxygen delivery and sufficient perfusion pressure. Maintaining the fluid balance is imperative for a normal kidney filtration process, which is essential for preserving the intra- and postoperative kidney function.

FUTURE DIRECTIONS

The review of the available literature regarding kidney function during cardiac surgery revealed a need for a more holistic approach to this subject.

Intraoperative hypotension and postoperative outcomes: a meta-analysis of randomised trials

INTRODUCTION

Intraoperative hypotension is associated with adverse postoperative outcomes; however these findings are supported only by observational studies. The aim of this meta-analysis of randomised trials was to compare the postoperative effects permissive management with targeted management of intraoperative blood pressure.

METHODS

We searched PubMed, Cochrane, and Embase up to June 2023 for studies comparing permissive (mean arterial pressure ≤60 mm Hg) with targeted (mean arterial pressure >60 mm Hg) intraoperative blood pressure management. Primary outcome was all-cause mortality at the longest follow-up available. Secondary outcomes were atrial fibrillation, myocardial infarction, acute kidney injury, delirium, stroke, number of patients requiring transfusion, time on mechanical ventilation, and length of hospital stay.

RESULTS

We included 10 randomised trials including a total of 9359 patients. Mortality was similar between permissive and targeted blood pressure management groups (89/4644 [1.9%] vs 99/4643 [2.1%], odds ratio 0.88, 95% confidence interval [CI], 0.65-1.18, P=0.38, I2=0% with nine studies included). Atrial fibrillation (102/3896 [2.6%] vs 130/3887 [3.3%] odds ratio 0.71, 95% CI 0.53-0.96, P=0.03, I2=0%), and length of hospital stay (mean difference -0.20 days, 95% CI -0.26 to -0.13, P<0.001, I2=0%) were reduced in the permissive management group. No significant differences were found in subgroup analysis for cardiac and noncardiac surgery.

CONCLUSION

Pooled randomised evidence shows that a target intraoperative mean arterial pressure ≤60 mm Hg is not associated with increased mortality; nevertheless it is surprisingly associated with a reduced rate of atrial fibrillation and of length of hospital stay.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42023393725.

Intraoperative hemodynamics and risk of cardiac surgery-associated acute kidney injury: An observation study and a feasibility clinical trial

Targeting greater pump flow and mean arterial pressure (MAP) during cardiopulmonary bypass (CPB) could potentially alleviate renal hypoxia and reduce the risk of postoperative acute kidney injury (AKI). Therefore, in an observational study of 93 patients undergoing on-pump cardiac surgery, we tested whether intraoperative hemodynamic management differed between patients who did and did not develop AKI. Then, in 20 patients, we assessed the feasibility of a larger-scale trial in which patients would be randomized to greater than normal target pump flow and MAP, or usual care, during CPB. In the observational cohort, MAP during hypothermic CPB averaged 68.8 ± 8.0 mmHg (mean ± SD) in the 36 patients who developed AKI and 68.9 ± 6.3 mmHg in the 57 patients who did not (p = 0.98). Pump flow averaged 2.4 ± 0.2 L/min/m2 in both groups. In the feasibility clinical trial, compared with usual care, those randomized to increased target pump flow and MAP had greater mean pump flow (2.70 ± 0.23 vs. 2.42 ± 0.09 L/min/m2 during the period before rewarming) and systemic oxygen delivery (363 ± 60 vs. 281 ± 45 mL/min/m2 ). Target MAP ≥80 mmHg was achieved in 66.6% of patients in the intervention group but in only 27.3% of patients in the usual care group. Nevertheless, MAP during CPB did not differ significantly between the two groups. We conclude that little insight was gained from our observational study regarding the impact of variations in pump flow and MAP on the risk of AKI. However, a clinical trial to assess the effects of greater target pump flow and MAP on the risk of AKI appears feasible.

Incorporating intraoperative blood pressure time-series variables to assist in prediction of acute kidney injury after type a acute aortic dissection repair: an interpretable machine learning model

BACKGROUND

Acute kidney injury (AKI) is a common and serious complication after the repair of Type A acute aortic dissection (TA-AAD). However, previous models have failed to account for the impact of blood pressure fluctuations on predictive performance. This study aims to develop machine learning (ML) models combined with intraoperative medicine and blood pressure time-series data to improve the accuracy of early prediction for postoperative AKI risk.

METHODS

Indicators reflecting the duration and depth of hypotension were obtained by analyzing continuous mean arterial pressure (MAP) monitored intraoperatively with multiple thresholds (<65, 60, 55, 50) set in the study. The predictive features were selected by logistic regression and the least absolute shrinkage and selection operator (LASSO), and 4 ML models were built based on the above features. The performance of the models was evaluated by area under receiver operating characteristic curve (AUROC), calibration curve and decision curve analysis (DCA). Shapley additive interpretation (SHAP) was used to explain the prediction models.

RESULTS

Among the indicators reflecting intraoperative hypotension, 65 mmHg showed a statistically superior difference to other thresholds in patients with or without AKI (p < .001). Among 4 models, the extreme gradient boosting (XGBoost) model demonstrated the highest AUROC: 0.800 (95% 0.683-0.917) and sensitivity: 0.717 in the testing set and was verified the best-performing model. The SHAP summary plot indicated that intraoperative urine output, cumulative time of mean arterial pressure lower than 65 mmHg outside cardiopulmonary bypass (OUT_CPB_MAP_65 time), autologous blood transfusion, and smoking were the top 4 features that contributed to the prediction model.

CONCLUSION

With the introduction of intraoperative blood pressure time-series variables, we have developed an interpretable XGBoost model that successfully achieve high accuracy in predicting the risk of AKI after TA-AAD repair, which might aid in the perioperative management of high-risk patients, particularly for intraoperative hemodynamic regulation.

Effect of preoperative risk on the association between intraoperative hypotension and postoperative acute kidney injury in cardiac surgery

BACKGROUND

Acute kidney injury (AKI), a common and severe complication after cardiac surgery, has been demonstrated to be associated with intraoperative hypotension (IOH). The reproducibility of this finding and whether preoperative risk modifies the association remain unclear. We hypothesised that the relationship between IOH and AKI after cardiac surgery varies by preoperative risk.

METHODS

We conducted a single-centre, retrospective cohort study to analyse the association between IOH and postoperative AKI by stratifying patients using preoperative risk factors. IOH was defined as a mean arterial pressure (MAP) of less than 65 mmHg and characterised by the cumulative duration and area under the curve (AUC).

RESULTS

Ten variables could be identified as risk factors: age, smoking status, NYHA III/Ⅳ, emergency surgery, peripheral vascular disease, cerebrovascular disease, heart failure, hypertension, previous cardiac surgery, and NT-proBNP concentration. The risk prediction model divided the patients into three equal-sized preoperative risk groups. Low-risk patients demonstrated no association between AKI and IOH of any severity, while high-risk patients demonstrated a statistically significant association between AKI and IOH with a cumulative duration greater than 104 min (adjusted odds ratio [OR]: 2.27, 95% confidence interval [CI]: 1.10-4.74; and adjusted OR: 3.63, 95% CI: 1.77-7.58) and an AUC greater than 905 mmHg min (adjusted OR: 2.08, 95% CI: 1.01-4.36; and adjusted OR: 4.00, 95% CI: 1.95-8.43).

CONCLUSION

IOH is a significant independent risk factor for AKI after cardiac surgery. Patients with higher baseline risk showed a more prominent relationship between IOH and postoperative AKI than low-risk patients.

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.

Postoperative delirium: identifying the patient at risk and altering the course: A narrative review

Postoperative delirium (POD) is a common neurocognitive syndrome seen in older patients after major surgery. POD is linked to longer stays in hospital and intensive care, a greater incidence of postoperative complications, worse functional outcome, and higher mortality. Researchers have not yet fully elucidated the exact pathophysiology of POD. Several risk factors that contribute to the development of POD have been identified, such as advanced age, cardiac or hip surgery, preoperative cognitive decline or delirium, disturbances in brain levels of neurotransmitters and information processing, oxidative stress and neuro-inflammation. Identifying patients at risk for POD enables a more precise and efficient allocation of medical resources and facilitates POD prevention and management. The present review addresses how to identify patients at risk of POD and summarizes the currently available evidence and best-practice recommendations for peri-operative management and prevention of POD.

Anaesthesia and environment: impact of a green anaesthesia on economics

The excessive growth of the health sector has created an industry that, while promoting health, is now itself responsible for a significant part of global environmental pollution. The health crisis caused by climate change urges us to transform healthcare into a sustainable industry. This review aims to raise awareness about this issue and to provide practical and evidence-based recommendations for anaesthesiologists.

Perioperative Neurocognitive Disorders in Adults Requiring Cardiac Surgery: Screening, Prevention, and Management

Neurocognitive changes are the most common complication after cardiac surgery, ranging from acute postoperative delirium to prolonged postoperative neurocognitive disorder. Changes in cognition are distressing to patients and families and associated with worse outcomes overall. This review outlines definitions and diagnostic criteria, risk factors for, and mechanisms of Perioperative Neurocognitive Disorders and offers strategies for preoperative screening and perioperative prevention and management of neurocognitive complications.

Antiplatelet therapy adjustment improved the radiomic characteristics of acute silent cerebral infarction after stent-assisted coiling in patients with high on-treatment platelet reactivity: A prospective study

Background

We aimed to investigate the effects of high on-treatment platelet reactivity (HPR) and antiplatelet therapy adjustment on high-risk radiomic features in patients with antiplatelet therapy adjustment on acute silent cerebral infarction (ASCI) who had unruptured intracranial aneurysms (UIA) after stent placement.

Methods

This single-institution study prospectively included 230 UIA patients who had ACSI after stent placement in our hospital between January 2015 and July 2020. All patients underwent magnetic resonance imaging with diffusion-weighted imaging (MRI-DWI) after stent placement and 1,485 radiomic features were extracted from each patient. The least absolute shrinkage and selection operator regression methods were used for selection of high-risk radiomic features associated with clinical symptoms. In addition, 199 patients with ASCI were classified into three groups: controls without HPR (n = 113), HPR patients with standard antiplatelet therapy (n = 63) and HPR patients with antiplatelet therapy adjustment (n = 23). We compared high-risk radiomic features between three groups.

Results

Of the patients who had acute infarction after MRI-DWI, 31 (13.5%) exhibited clinical symptoms. Eight risk radiomic features associated with clinical symptoms were selected, and the radiomics signature exhibited good performance. In ASCI patients, compared with controls, the radiomic characteristics of ischemic lesion in HPR patients were consistent with the following high-risk radiomic features associated with clinical symptoms: higher gray-level values, greater variance in intensity values, and greater homogeneity. However, the adjustment of antiplatelet therapy in HPR patients modified the high-risk radiomic features, which showed lower gray-level values, less variance in intensity values, and more heterogeneous texture. The radiomic shape feature of elongation showed no notable difference between three groups.

Conclusion

Adjustment of antiplatelet therapy might reduce the high-risk radiomic features of UIA patients with HPR after stent placement.

Predictive Value of Multimodality Intraoperative Neurophysiological Monitoring During Cardiac Surgery

INTRODUCTION

This study aimed to determine the ability of multimodality intraoperative neurophysiologic monitoring, including somatosensory evoked potentials (SSEP) and EEG, to predict perioperative clinical stroke and stroke-related mortality after open-heart surgery in high-risk patients.

METHODS

The records of all consecutive patients who underwent coronary artery bypass grafting, and cardiac valve repair/replacement with high risk for stroke who underwent both SSEP and EEG recording at the University of Pittsburgh Medical Center between 2009 and 2015 were reviewed. Sensitivity and specificity of these modalities to predict in-hospital clinical strokes and stroke-related mortality were calculated.

RESULTS

A total of 531 patients underwent open cardiac procedures monitored using SSEP and EEG. One hundred thirty-one patients (24.67%) experienced significant changes in either modality. Fourteen patients (2.64%) suffered clinical strokes within 24 hours after surgery, and eight patients (1.50%) died during their hospitalization. The incidence of in-hospital clinical stroke and stroke-related mortality among patients who experienced a significant change in monitoring compared with those with no significant change was 11.45% versus 1.75%. The sensitivity and specificity of significant changes in either SSEP or EEG to predict in-hospital major stroke and stroke-related mortality were 0.93 and 0.77, respectively.

CONCLUSIONS

Intraoperative neurophysiologic monitoring with SSEP and EEG has high sensitivity and specificity in predicting perioperative stroke and stroke-related mortality after open cardiac procedures. These results support the benefits of multimodality neuromonitoring during cardiac surgery.

Diagnosis, pathophysiology and preventive strategies for cardiac surgery-associated acute kidney injury: a narrative review

Acute kidney injury (AKI) is a common and serious complication of cardiac surgery and is associated with increased mortality and morbidity, accompanied by a substantial economic burden. The pathogenesis of cardiac surgery-associated acute kidney injury (CSA-AKI) is multifactorial and complex, with a variety of pathophysiological theories. In addition to the existing diagnostic criteria, the exploration and validation of biomarkers is the focus of research in the field of CSA-AKI diagnosis. Prevention remains the key to the management of CSA-AKI, and common strategies include maintenance of renal perfusion, individualized blood pressure targets, balanced fluid management, goal-directed oxygen delivery, and avoidance of nephrotoxins. This article reviews the pathogenesis, definition and diagnosis, and pharmacological and nonpharmacological prevention strategies of AKI in cardiac surgical patients.

The Conundrum of Systemic Arterial Pressure Management on Cardiopulmonary Bypass

The recently released EACTS/EACTA/EBCP guidelines on cardiopulmonary bypass (CPB) in adult cardiac surgery [...].

Subject-wise model generalization through pooling and patching for regression: Application on non-invasive systolic blood pressure estimation

BACKGROUND

Subject-wise modeling using machine learning is useful in many applications requiring low error and complexity, such as wearable medical devices. However, regression accuracy depends highly on the data available to train the model and the model's generalization ability. Adversely, the prediction error may increase severely if unknown data patterns test the model; such a model is known to be overfitted. In medicine-related applications, such as Non-Invasive Blood Pressure (NIBP) estimation, the high error renders the estimation model useless and dangerous.

METHODS

This paper presents a novel algorithm to handle overfitting by editing the training data to achieve generalization for subject-wise models. The pooling and patching (PaP) algorithms use a relatively short record segment of a subject as a Key-Segment (KS) to search through a larger dataset for similar subjects. Then samples taken from the matched subjects' pool records are used to patch the original subject's KS. Due to the significance of systolic blood pressure (SBP) and the complexity of its variability, non-invasive estimation of SBP from electrocardiography (ECG) and photoplethysmography (PPG) is introduced as an application to assess the algorithm. The study was performed on 2051 subjects with a wide range of age, height, weight, length, and health status. The subjects' records were taken from a large public dataset, VitalDB, which is acquired from subjects undergoing different surgeries. Finally, all the results are obtained without using other model generalization techniques.

RESULTS

The generalization effect of the proposed algorithm, PaP, significantly outperformed cross-validation, which is widely used in regression model generalization. Moreover, the testing results show that a KS of 200 to 2000 samples is sufficient for providing high accuracy for much longer testing data of about 12000 to 24000 samples long, which is less than %10 of the record length on average. Furthermore, compared to other works based on the same dataset, PaP provides a significantly lower mean error of -0.75 ± 5.51 mmHg, with a small training data portion of 15% over 2051 subjects.

High versus low blood pressure targets for cardiac surgery while on cardiopulmonary bypass

BACKGROUND

Cardiac surgery is performed worldwide. Most types of cardiac surgery are performed using cardiopulmonary bypass (CPB). Cardiac surgery performed with CPB is associated with morbidities. CPB needs an extracorporeal circulation that replaces the heart and lungs, and performs circulation, ventilation, and oxygenation of the blood. The lower limit of mean blood pressure to maintain blood flow to vital organs increases in people with chronic hypertension. Because people undergoing cardiac surgery commonly have chronic hypertension, we hypothesised that maintaining a relatively high blood pressure improves desirable outcomes among the people undergoing cardiac surgery with CPB.

OBJECTIVES

To evaluate the benefits and harms of higher versus lower blood pressure targets during cardiac surgery with CPB.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search of databases was November 2021 and trials registries in January 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing a higher blood pressure target (mean arterial pressure 65 mmHg or greater) with a lower blood pressure target (mean arterial pressure less than 65 mmHg) in adults undergoing cardiac surgery with CPB.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Primary outcomes were 1. acute kidney injury, 2. cognitive deterioration, and 3. all-cause mortality. Secondary outcomes were 4. quality of life, 5. acute ischaemic stroke, 6. haemorrhagic stroke, 7. length of hospital stay, 8. renal replacement therapy, 9. delirium, 10. perioperative transfusion of blood products, and 11. perioperative myocardial infarction. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included three RCTs with 737 people compared a higher blood pressure target with a lower blood pressure target during cardiac surgery with CPB. A high blood pressure target may result in little to no difference in acute kidney injury (risk ratio (RR) 1.30, 95% confidence interval (CI) 0.81 to 2.08; I² = 72%; 2 studies, 487 participants; low-certainty evidence), cognitive deterioration (RR 0.82, 95% CI 0.45 to 1.50; I² = 0%; 2 studies, 389 participants; low-certainty evidence), and all-cause mortality (RR 1.33, 95% CI 0.30 to 5.90; I² = 49%; 3 studies, 737 participants; low-certainty evidence). No study reported haemorrhagic stroke. Although a high blood pressure target may increase the length of hospital stay slightly, we found no differences between a higher and a lower blood pressure target for the other secondary outcomes. We also identified one ongoing RCT which is comparing a higher versus a lower blood pressure target among the people who undergo cardiac surgery with CPB.

AUTHORS' CONCLUSIONS

A high blood pressure target may result in little to no difference in patient outcomes including acute kidney injury and mortality. Given the wide CIs, further studies are needed to confirm the efficacy of a higher blood pressure target among those who undergo cardiac surgery with CPB.

Higher blood pressure versus normotension targets to prevent acute kidney injury: a systematic review and meta-regression of randomized controlled trials

BACKGROUND

Renal hypoperfusion is one of the most common causes of acute kidney injury (AKI), especially in shock and perioperative patients. An optimal blood pressure (BP) target to prevent AKI remains undetermined. We conducted a systematic review and meta-analysis of available randomized clinical trial (RCT) results to address this knowledge gap.

METHODS

From inception to May 13, 2022, we searched Ovid Medline, EMBASE, Cochrane Library, SCOPUS, clinicaltrials.gov, and WHO ICTRP for RCTs comparing higher BP target versus normotension in hemodynamically unstable patients (shock, post-cardiac arrest, or surgery patients). The outcomes of interest were post-intervention AKI rate and renal replacement therapy (RRT) rate. Two investigators independently screened the citations and reviewed the full texts for eligible studies according to a predefined form.

RESULTS

Twelve trials were included, enrolling a total of 5759 participants, with shock, non-cardiac, and cardiac surgery patients accounting for 3282 (57.0%), 1687 (29.3%) and 790 (13.7%) patients, respectively. Compared to lower mean arterial blood pressure (MAP) targets that served as normotension, targeting higher MAP had no significant effect on AKI rates in shock (RR [95% CI] = 1.10 [0.93, 1.29]), in cardiac-surgery (RR [95% CI] = 0.87 [0.73, 1.03]) and non-cardiac surgery patients (RR [95% CI] = 1.25 [0.98, 1.60]) using random-effects meta-analyses. In shock patients with premorbid hypertension, however, targeting MAP above 70 mmHg resulted in significantly lower RRT risks, RR [95%CI] = 1.20 [1.03, 1.41], p < 0.05.

CONCLUSIONS

Targeting a higher MAP in shock or perioperative patients may not be superior to normotension, except in shock patients with premorbid hypertension. Further studies are needed to assess the effects of a high MAP target to preventing AKI in hypertensive patients across common settings of hemodynamic instability. Trial registration This systematic review has been registered on PROSPERO ( CRD42021286203 ) on November 19, 2021, prior to data extraction and analysis.

Timing, Threshold, and Duration of Intraoperative Hypotension in Cardiac Surgery: Their Associations With Postoperative Delirium

OBJECTIVES

To study the timing, threshold, and duration of intraoperative hypotension (IOH) associated with the risk of postoperative delirium (POD).

DESIGN

A single-center retrospective observational study.

SETTING

University teaching hospital.

PARTICIPANTS

A total of 503 adult patients who underwent cardiac valvular surgery that required cardiopulmonary bypass (CPB).

MEASUREMENTS AND MAIN RESULTS

The authors predefined the following 4 periods: (1) during surgery, (2) pre-CPB, (3) during CPB, and (4) post-CPB, and 8 thresholds of mean arterial pressure for IOH according to every 5 mmHg between 50 mmHg and 85 mmHg. The authors calculated the cumulative duration below the 8 thresholds in each period. The primary outcome was delirium defined as a score of ≥4 for at least one Intensive Care Delirium Screening Checklist assessment during 48 h after the surgery. Among 503 patients, POD occurred in 95 patients (18.9%). There was no significant association of POD with all of the thresholds of IOH in the periods of pre-CPB, during CPB, and during surgery. However, in the post-CPB period, the patients with POD had a significantly longer cumulative duration of IOH according to all of the thresholds of mean arterial pressure. In multivariate analyses, 4 IOH thresholds in the post-CPB period were associated independently with POD: <60 mmHg (odds ratio [OR] =1.84 [95% CI 1.10-3.10]), <65 mmHg (OR = 1.72 [1.01-2.92]), <70 mmHg (OR = 1.83 [1.03-3.26]), and <75 mmHg (OR = 1.94 [1.02-3.69]).

CONCLUSIONS

A longer cumulative duration of IOH with the threshold between <60 and <75 mmHg that occurred after CPB was independently associated with the risk of POD.

Stroke, Seizures, Hallucinations and Postoperative Delirium as Neurological Complications after Cardiac Surgery and Percutaneous Valve Replacement

(1) Background: Neurological complications such as acute ischemic stroke or postoperative delirium are frequent after cardiac surgery or percutaneous valve replacement. This study aimed to identify corresponding risk factors. (2) Methods: 297 patients with percutaneous valve replacement or cardiac surgery were postoperatively screened for neurological complications such as delirium, stroke, seizures and hallucinations twice daily for three days. Pre- and perioperative risk factors were evaluated in a multivariate model. (3) Results: Neurological complications occurred in 43.8% (n = 130) as composed of delirium (43.43%, n = 129), stroke (2.7%, n = 8), seizures (1.35%, n = 4) and real hallucinations (3.36%, n = 10). Multiple logistic regression revealed an association of neurological complications with lower Montreal Cognitive Assessment scores (Exp(B) 2.042; 95% CI, 1.183−3.525, p = 0.010), older age (Exp(B) 1.071; 95% CI, 1.036−1.107, p < 0.001), red blood cell transfusions until postoperative day 3 (Exp(B) 1.157; 95% CI, 1.030−1.300, p = 0.014), history of heart failure (Exp(B) 1.985; 95% CI, 1.130−3.487, p = 0.017) and increased CRP levels (Exp(B) 1.004; 95% CI, 1.000−1.008, p = 0.037). (4) Conclusions: Postoperative delirium remains a frequent complication after cardiac surgery, while stroke and seizures occur rarely. A preoperative risk profile including older age, history of heart failure and cognitive impairment was identified for a complicated postoperative course. However, the impact of an intense inflammatory response must not be neglected.

Comparison of Machine Learning Models Including Preoperative, Intraoperative, and Postoperative Data and Mortality After Cardiac Surgery

IMPORTANCE

A variety of perioperative risk factors are associated with postoperative mortality risk. However, the relative contribution of routinely collected intraoperative clinical parameters to short-term and long-term mortality remains understudied.

OBJECTIVE

To examine the performance of multiple machine learning models with data from different perioperative periods to predict 30-day, 1-year, and 5-year mortality and investigate factors that contribute to these predictions.

DESIGN, SETTING, AND PARTICIPANTS

In this prognostic study using prospectively collected data, risk prediction models were developed for short-term and long-term mortality after cardiac surgery. Included participants were adult patients undergoing a first-time valve operation, coronary artery bypass grafting, or a combination of both between 1997 and 2017 in a single center, the University Medical Centre Groningen in the Netherlands. Mortality data were obtained in November 2017. Data analysis took place between February 2020 and August 2021.

EXPOSURE

Cardiac surgery.

MAIN OUTCOMES AND MEASURES

Postoperative mortality rates at 30 days, 1 year, and 5 years were the primary outcomes. The area under the receiver operating characteristic curve (AUROC) was used to assess discrimination. The contribution of all preoperative, intraoperative hemodynamic and temperature, and postoperative factors to mortality was investigated using Shapley additive explanations (SHAP) values.

RESULTS

Data from 9415 patients who underwent cardiac surgery (median [IQR] age, 68 [60-74] years; 2554 [27.1%] women) were included. Overall mortality rates at 30 days, 1 year, and 5 years were 268 patients (2.8%), 420 patients (4.5%), and 612 patients (6.5%), respectively. Models including preoperative, intraoperative, and postoperative data achieved AUROC values of 0.82 (95% CI, 0.78-0.86), 0.81 (95% CI, 0.77-0.85), and 0.80 (95% CI, 0.75-0.84) for 30-day, 1-year, and 5-year mortality, respectively. Models including only postoperative data performed similarly (30 days: 0.78 [95% CI, 0.73-0.82]; 1 year: 0.79 [95% CI, 0.74-0.83]; 5 years: 0.77 [95% CI, 0.73-0.82]). However, models based on all perioperative data provided less clinically usable predictions, with lower detection rates; for example, postoperative models identified a high-risk group with a 2.8-fold increase in risk for 5-year mortality (4.1 [95% CI, 3.3-5.1]) vs an increase of 11.3 (95% CI, 6.8-18.7) for the high-risk group identified by the full perioperative model. Postoperative markers associated with metabolic dysfunction and decreased kidney function were the main factors contributing to mortality risk.

CONCLUSIONS AND RELEVANCE

This study found that the addition of continuous intraoperative hemodynamic and temperature data to postoperative data was not associated with improved machine learning-based identification of patients at increased risk of short-term and long-term mortality after cardiac operations.

Intraoperative hyperoxygenation may negatively affect postoperative cognitive functions in coronary artery bypass graft operations: A randomized controlled study

OBJECTIVE

In this study, it was aimed to compare various parameters during surgery and postoperative cognitive functions in patients undergoing coronary artery bypass graft (CABG) surgery using different levels of perioperative oxygen.

METHODS

One hundred patients scheduled for elective CABG surgery were included in the study. The patients were divided into two groups according to arterial oxygen levels during surgery. In the normoxia group (NG) (n = 50), partial arterial oxygen pressure (PaO₂ ) was between ≥100 and <180 mmHg with at least 40% fraction of inspired oxygen (FiO₂ ) mechanical ventilation (MV), and in the hyperoxia group (HG) (n = 50), PaO₂ was ≥180 mmHg with 100% FiO₂ MV. Hemodynamic parameters, peripheral oxygen saturation (SpO₂ ), regional cerebral oxygen saturation (rSO₂ ) measured from bilateral sensors, and blood gas values were recorded at the planned measurement times. Postoperative features (mortality and infection rates, length of stay in the hospital, and intensive care unit) and complications of the patients have been recorded (low cardiac output syndrome, renal failure, delirium). Mini-Mental State Examination (MMSE) test was applied to the patients before and at the 12th, 24th hours; on the first, third, sixth months after surgery.

RESULTS

Extubation time was found to be shorter in NG (p < .05). Between the groups, rSO₂ and mean arterial pressure were found to be significantly lower in HG at the time of T4 measurement (p = .042, p = .038, respectively). MMSE values of the groups at the first, third, and sixth months were found to be significantly higher in NG (p = .017, p = .014, p = .002, respectively).

CONCLUSION

Hyperoxemia application during CABG may be associated with worse postoperative late-term cognitive functions.