Perioperative extracorporeal membrane oxygenation support for pulmonary endarterectomy: A 17-year experience from the UK national cohort.

BACKGROUND: Pulmonary endarterectomy (PEA) is the guideline-recommended treatment for patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, some patients develop severe cardiopulmonary compromise before surgery, intraoperatively, or early postoperatively. This may result from advanced CTEPH, reperfusion pulmonary edema, massive endobronchial bleeding, or right ventricular (RV) failure secondary to residual pulmonary hypertension. Conventional cardiorespiratory support is ineffective when these complications are severe. Since 2005, we used extracorporeal membrane oxygenation (ECMO) as a rescue therapy for this group. We review our experience with ECMO support in these patients. METHODS: This study was a retrospective analysis of patients who received perioperative ECMO for PEA from a single national center from August 2005 to July 2022. Data were prospectively collected. RESULTS: One hundred and ten patients (4.7%) had extreme cardiorespiratory compromise requiring perioperative ECMO. Nine were established on ECMO before PEA. Of those who received ECMO postoperatively, 39 were for refractory reperfusion lung injury, 20 for RV failure, 31 for endobronchial bleeding, and the remaining 11 were for "other" reasons, such as cardiopulmonary resuscitation following late tamponade and aspiration pneumonitis. Sixty-two (56.4%) were successfully weaned from ECMO. Fifty-seven patients left the hospital alive, giving a salvage rate of 51.8%. Distal disease (Jamieson Type III) and significant residual pulmonary hypertension were also predictors of mortality on ECMO support. Overall, 5- and 10-year survival in patients who were discharged alive following ECMO support was 73.9% (SE: 6.1%) and 58.2% (SE: 9.5%), respectively. CONCLUSIONS: Perioperative ECMO support has an appropriate role as rescue therapy for this group. Over 50% survived to hospital discharge. These patients had satisfactory longer-term survival.

Effects of general versus subarachnoid anaesthesia on circadian melatonin rhythm and postoperative delirium in elderly patients undergoing hip fracture surgery: A prospective cohort clinical trial.

BACKGROUND: Circadian rhythm disturbance is common postoperatively in older patients with hip fractures, which may contribute to the development of postoperative delirium (POD). As a reliable biomarker of endogenous circadian rhythms, melatonin regulates the sleep-wake cycle and environmental adaptation, and its secretory rhythm may be modified by anaesthesia and surgery. This study compared the impact of subarachnoid anaesthesia (SA) and general anaesthesia (GA), on the peak of melatonin secretion (primary outcome), the circadian rhythm of melatonin, cortisol and sleep, and the POD incidence (secondary outcome). METHODS: In this prospective cohort observational study, hip fracture surgery patients were enrolled and assigned to receive either SA or GA. Postoperative plasma melatonin and cortisol levels were dynamically measured every six hours on seven time-points, and the circadian rhythm parameters including mesor, amplitude, and acrophase were calculated. Subjective and objective sleep assessments were performed by sleep diaries and sleep trackers, respectively. The Confusion Assessment Method was used twice daily by a specific geriatrician to screen for POD occurrence. FINDINGS: In a cohort of 138 patients who underwent hip fracture surgery, the circadian rhythm disruption of the patients in the GA group (n=69) was greater than the SA group (n=69). Compared with SA, GA provided the lower peak concentration, mesor, and amplitude of melatonin secretion on postoperative day 1 (p < 0.05). Patients in the GA group experienced higher awakenings, more sleep deprivation, and poor sleep quality on surgery day (p < 0.05). A proportion of 12 patients in the SA group (17.4%) and 24 patients in the GA group (34.8%) experienced POD (p = 0.020). INTERPRETATION: These results suggest that SA may be superior to GA in elderly patients undergoing hip fracture surgery as SA is associated with less impairment of the melatonin rhythm and sleep patterns, and fewer POD occurrences. FUNDING: The study was supported by the National Natural Science Foundation of China (81971012, 81873726, 81901095, 81701052, and 81801070), Key Clinical Projects of Peking University Third Hospital (BYSYZD2019027), and Peking University "Clinical Medicine plus X" Youth Project (PKU2020LCXQ016).

Regional extracorporeal membrane oxygenation retrieval service during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic: an interdisciplinary team approach to maintain service provision despite increased demand.

OBJECTIVES: Coronavirus disease 2019 is a new contagious disease that has spread rapidly across the world. It is associated with high mortality in those who develop respiratory complications and require admission to intensive care. Extracorporeal membrane oxygenation (ECMO) is a supportive therapy option for selected severely ill patients who deteriorate despite the best supportive care. During the coronavirus disease 2019 pandemic, extra demand led to staff reorganization; hence, cardiac surgery consultants joined the ECMO retrieval team. This article describes how we increased service provisions to adapt to the changes in activity and staffing. METHODS: The data were collected from 16 March 2020 to 8 May 2020. The patients were referred through a dedicated Web-based referral portal to cope with increasing demand. The retrieval team attended the referring hospital, reviewed the patients and made the final decision to proceed with ECMO. RESULTS: We reported 41 ECMO retrieval runs during this study period. Apart from staffing changes, other retrieval protocols were maintained. The preferred cannulation method for veno-venous ECMO was drainage via the femoral vein and return to the right internal jugular vein. There were no complications reported during cannulation or transport. CONCLUSIONS: Staff reorganization in a crisis is of paramount importance. For those with precise transferrable skills, experience can be gained quickly with appropriate supervision. Therefore, the team members were selected based on skill mix rather than on roles that are more traditional. We have demonstrated that an ECMO retrieval service can be reorganized swiftly and successfully to cope with the sudden increase in demand by spending cardiac surgeons services to supplement the anaesthetic-intensivist roles.

European Association of Cardiothoracic Anesthesiology (EACTA) Cardiothoracic and Vascular Anesthesia Fellowship Curriculum: First Edition.

This special article summarizes the design and certification process of the European Association of Cardiothoracic Anesthesiology (EACTA) Cardiothoracic and Vascular Anesthesia (CTVA) Fellowship Program. The CTVA fellowship training includes a two-year curriculum at an EACTA-accredited educational facility. Before fellows are accepted into the program, they must meet a number of requirements, including evidence of a valid license to practice medicine, a specialist degree examination in anesthesiology, and appropriate language skills as required in the host centers. The CVTA Fellowship Program has 2 sequential and complementary levels of training-both with a modular structure that allows for individual planning and also takes into account the differing national healthcare needs and requirements of the 36 countries represented in EACTA. The basic training period focuses on the anesthetic management of patients undergoing cardiac, thoracic, and vascular surgery and related procedures. The advanced training period is intended to deepen and to extend the clinical and nontechnical skills that fellows have acquired during the basic training. The goal of the EACTA fellowship is to produce highly trained and competent perioperative physicians who are able to care for patients undergoing cardiac, thoracic, and vascular anesthesia.

The Effects of Escalation of Respiratory Support and Prolonged Invasive Ventilation on Outcomes of Cardiac Surgical Patients: A Retrospective Cohort Study.

OBJECTIVES: The aim of this study was to determine the effects of escalation of respiratory support and prolonged postoperative invasive ventilation on patient-centered outcomes, and identify perioperative factors associated with these 2 respiratory complications. DESIGN: A retrospective cohort analysis of cardiac surgical patients admitted to the cardiothoracic intensive care unit (ICU) between August 2015 and January 2018. Escalation of respiratory support was defined as "unplanned continuous positive airway pressure," "non-invasive ventilation," or "reintubation" after surgery; prolonged invasive ventilation was defined as "invasive ventilation beyond the first 12 hours following surgery." The primary endpoint was the composite of escalation of respiratory support and prolonged ventilation. SETTING: Tertiary cardiothoracic ICU. PARTICIPANTS: A total of 2,098 patients were included and analyzed. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The composite of escalation of support or prolonged ventilation occurred in 509 patients (24.3%). Patients who met the composite had higher mortality (2.9% v 0.1%; p < 0.001) and longer median [interquartile range] length of ICU (2.1 [1.0-4.9] v 0.9 [0.8-1.0] days; p < 0.0001) and hospital (10.6 [8.0-16.0] v 7.2 [6.2-10.0] days; p < 0.0001) stay. Hypoxemia and anemia on admission to ICU were the only 2 factors independently associated with the need for escalation of respiratory support or prolonged invasive ventilation. CONCLUSIONS: Escalation of respiratory support or prolonged invasive ventilation is frequently seen in cardiac surgery patients and is highly associated with increased mortality and morbidity. Hypoxemia and anemia on admission to the ICU are potentially modifiable factors associated with escalation of respiratory support or prolonged invasive ventilation.

Assessment of safety and bleeding risk in the use of extracorporeal membrane oxygenation for multitrauma patients: A multicenter review.

BACKGROUND: Respiratory failure is the most common form of organ failure following traumatic injury. Previously, there have been concerns regarding extracorporeal membrane oxygenation (ECMO) use in the trauma setting because of the increased risk of bleeding and thrombotic complications. We sought to examine the management of trauma patients with ECMO and to assess the safety and outcome of its use. METHODS: Data of all patients who experienced a traumatic injury and were supported with ECMO were collected from the five National Respiratory ECMO centers in the United Kingdom over the period from December 2011 to May 2017. Primary outcome variables included 30-day and 6-month mortality and exacerbation of underlying traumatic injury after ECMO commencement. Secondary outcome variables included duration of ECMO support, thrombotic complications, and worsening of intracranial injury. RESULTS: Fifty-two patients were identified. The overall hospital mortality was 15%. The incidence of bleeding complications was 50%, the majority of these not requiring intervention. Forty patients underwent surgical management prior to ECMO commencement; only four patients required take-back to the operating theater. There was no significant difference between the bleeding and nonbleeding groups in time of injury to ECMO commencement (median difference, 4.5 days; 95% CI, -3 to 3 days; p = 0.75). There was no statistically significant difference between the bleeding and nonbleeding groups in regard to time to anticoagulation commencement after starting ECMO (median difference, - 1 hour; 95% CI, -48 to 2 hours; p = 0.29) or after trauma (median difference, - 1 day; 95% CI, -4 to 2 days; p = 0.41). Nineteen patients were diagnosed with significant neurological injury. Twelve of these patients were anticoagulated. Two patients died as a direct result of worsening neurological injury. CONCLUSIONS: Our findings suggest that the use of ECMO in trauma patients does not exacerbate primary traumatic injury regardless of anticoagulation commencement and may confer a survival benefit. Neurological injury should not be seen as an absolute contraindication to ECMO. LEVEL OF EVIDENCE: Therapeutic/Care Management, Level V.

Usefulness of the STOP-Bang Questionnaire in a Cardiac Surgical Population.

OBJECTIVE: The aim of this study was to assess the predictive accuracy of the STOP-Bang questionnaire in relation to obstructive sleep apnea (OSA) detected by nocturnal oximetry, as well as postoperative outcomes, in a population undergoing cardiac surgery. DESIGN: A prospective observational cohort study. SETTING: The specialist cardiothoracic center at the Royal Papworth Hospital, Cambridge University Health Partners, United Kingdom. PARTICIPANTS: All adult patients, undergoing elective coronary artery bypass grafting with or without cardiac valve surgery between March 2013 and July 2014 were included. The authors excluded patients participating in other interventional studies, those who had a tracheostomy before surgery, and those who required emergency surgery or were due to be admitted on the day of surgery. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Cardiac surgical patients were screened for the risk of OSA with the use of STOP-Bang questionnaire. The presence of OSA prior to surgery was assessed with overnight oximetry. The predictive performance of the STOP-Bang questionnaire was assessed by calculating sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve (AUC)-receiver operating characteristic curve (ROC). Multiple-logistic regression models were used to assess for associations between the STOP-Bang scores and postoperative outcomes. The STOP-Bang questionnaire discriminated poorly between mild OSA (AUC-ROC 0.57 [95% confidence interval (CI) 0.47-0.67]) and moderate/severe OSA (AUC-ROC 0.82 (95% CI 0.69-0.95)]. Accuracy was increased by modifying the cut-off value to 6 or greater, with sensitivity and specificity of 75% and 77%, respectively. A STOP-Bang score indicating the possibility of OSA was not significantly associated with prolonged intensive care unit lengths of stay (hazard ratio [HR] 1.1; 95% CI 0.99-1.19; p = 0.08) or postoperative complications (odds ratio [OR] 1.0; 95% CI 0.59-1.72; p = 0.98). CONCLUSIONS: In the study population, a STOP-Bang questionnaire score of 3 or greater had limited predictive value for identifying cardiac surgical patients at high risk of OSA. STOP-Bang scores were not significantly associated with worse postoperative outcomes. A STOP-Bang score of 6 or greater could help identify patients in need of a sleep study to confirm the presence of OSA as such patients may be at increased risk of postoperative complications.

Prediction of Patient Length of Stay on the Intensive Care Unit Following Cardiac Surgery: A Logistic Regression Analysis Based on the Cardiac Operative Mortality Risk Calculator, EuroSCORE.

OBJECTIVE: The aim of this study was to develop a statistical model based on patient parameters to predict the length of stay (LOS) in the intensive care unit (ICU) following cardiac surgery in a single center. DESIGN: Data were collected from patients admitted to the ICU following cardiac surgery over a 10-year period (2006-2016). Both the additive and logistic EuroSCORE were calculated, and logistic regression analysis was carried out to formulate a model relating the predicted LOS to the EuroSCORE. This model was used to stratify patients into short stay (less than 48 hours) or long stay (more than 48 hours). SETTING: ICU at Papworth Hospital, Cambridgeshire. PARTICIPANTS: A total of 18,377 consecutive patients who had been in ICU following cardiac surgery (coronary graft bypass surgery, valve surgery, or a combination of both). INTERVENTIONS: This was an observational study. MEASUREMENTS AND MAIN RESULTS: The authors have shown that both the additive and logistic EuroSCORE can be used to stratify cardiac surgical patients in various predicted LOS in ICU. Further adjustments can be made to increase the number of patients correctly identified as either short stay or long stay. Comparison of the model predictions to the data demonstrated a high overall accuracy of 79.77%, and receiver operating characteristic curve analysis showed the area under the curve to be 0.7296. CONCLUSION: This analysis of an extensive data set shows that patient LOS in ICU after cardiac surgery in a single center can be predicted accurately using the simple cardiac operative risk scoring tool EuroSCORE. Using such predictions has the potential to improve ICU resource management.

Central Veno-Arterial Extracorporeal Membrane Oxygenation (C-VA-ECMO) After Cardiothoracic Surgery: A Single-Center Experience.

OBJECTIVES: Central veno-arterial extracorporeal membrane oxygenation (C-VA-ECMO) provides temporary cardiorespiratory support for patients in heart failure who cannot be weaned from cardiopulmonary bypass successfully. Outcomes are influenced by the reversibility of the initial insult and complications of the technique. METHODS: The authors reviewed their single-center experience over the last 8 years to inform future practice. The study included all patients supported with C-VA-ECMO after cardiothoracic surgery between January 2008 and July 2016. The authors identified mortality risk factors using logistic regression analysis and chi-square tests. RESULTS: One hundred and one patients were supported with C-VA-ECMO during the studied period. Weaning from ECMO was successful in 57.4% of patients, whereas 7.9% were bridged to veno-venous ECMO, 2% to peripheral veno-arterial ECMO, and 2% to biventricular ventricular assist devices. In-hospital and 1-year survival for all patients was 33.7% and 27.7%, respectively. Survival was considerably higher in transplantation patients (n = 11), at 63.6% and 54.5%, respectively. Risk factors linked to in-hospital mortality were age older than 70 years, lactate level greater than 4 mmol/L after 48 hours, and hepatic and kidney failure during ECMO support. CONCLUSIONS: Overall one-third of patients in the cohort who the authors believe would otherwise have died from postcardiotomy cardiogenic shock survived because C-VA-ECMO was commenced after cardiac surgery. Survival is greater in transplantation patients necessitating this form of support during or immediately after surgery.

Association between severity of untreated sleep apnoea and postoperative complications following major cardiac surgery: a prospective observational cohort study.

OBJECTIVE: To examine whether untreated sleep apnoea is associated with prolonged Intensive Care Unit (ICU) stay and increased frequency of postoperative ICU complications, in patients undergoing major cardiac surgery. PATIENTS/METHODS: Adult patients, undergoing elective coronary artery bypass grafting with or without cardiac valve surgery, between March 2013 and July 2014, were considered. We excluded patients participating in other interventional studies, those who had a tracheostomy before surgery, required emergency surgery or were due to be admitted on the day of surgery. Patients underwent inpatient overnight oximetry on the night prior to their surgery to assess for the presence of sleep apnoea. Since oximetry alone cannot differentiate obstructive from central apnoea, the results are reported as sleep apnoea which was diagnosed in patients with an arterial oxygen desaturation index (ODI) ≥ 5/h. RESULTS: The primary outcome measure was length of stay (LoS) in ICU in days. The secondary outcome was a composite measure of postoperative complications in ICU. Multivariate models were developed to assess associations between ODI and the primary and secondary outcome measures, adjusting for preselected predictor variables, relative to primary and secondary outcomes. There was no significant association between ODI and ICU LoS, HR 1.0, 95% CI 0.99-1.02; p = 0.12. However we did find a significant association between ODI and postoperative complications in the ICU, OR = 1.1; 95% CI 1.02-1.17; p = 0.014. The probability of developing complications rose with higher ODI, reflecting sleep apnoea severity. CONCLUSIONS: Acknowledging the limitations of this prospective study, untreated sleep apnoea did not predict an increased length of stay in ICU but we do report an association with postoperative complications in patients undergoing major cardiac surgery.

Use of a Structured Mirrors Intervention Does Not Reduce Delirium Incidence But May Improve Factual Memory Encoding in Cardiac Surgical ICU Patients Aged Over 70 Years: A Pilot Time-Cluster Randomized Controlled Trial.

Introduction: Post-operative delirium remains a significant problem, particularly in the older surgical patient. Previous evidence suggests that the provision of supplementary visual feedback about ones environment via the use of a mirror may positively impact on mental status and attention (core delirium diagnostic domains). We aimed to explore whether use of an evidence-based mirrors intervention could be effective in reducing delirium and improving post-operative outcomes such as factual memory encoding of the Intensive Care Unit (ICU) environment in older cardiac surgical patients. Methods: This was a pilot time-cluster randomized controlled trial at a 32-bed ICU, enrolling 223 patients aged 70 years and over, admitted to ICU after elective or urgent cardiac surgery from October 29, 2012 to June 23, 2013. The Mirrors Group received a structured mirrors intervention at set times (e.g., following change in mental status). The Usual Care Group received the standard care without mirrors. Primary outcome was ICU delirium incidence; secondary outcomes were ICU delirium days, ICU days with altered mental status or inattention, total length of ICU stay, physical mobilization (balance confidence) at ICU discharge, recall of factual and delusional ICU memories at 12 weeks, Health-Related Quality of Life at 12 weeks, and acceptability of the intervention. Results: The intervention was not associated with a significant reduction in ICU delirium incidence [Mirrors: 20/115 (17%); Usual Care: 17/108 (16%)] or duration [Mirrors: 1 (1-3); Usual Care: 2 (1-8)]. Use of the intervention on ICU was predictive of significantly higher recall of factual (but not delusional) items at 12 weeks after surgery (p = 0.003) and acceptability was high, with clinicians using mirrors at 86% of all recorded hourly observations. The intervention did not significantly impact on other secondary outcomes. Conclusion: Use of a structured mirrors intervention on the post-operative ICU does not reduce delirium, but may result in improved factual memory encoding in older cardiac surgical patients. This effect may occur via mechanisms unrelated to delirium, altered mental status, or inattention. The intervention may provide a new means of improving outcomes in patients at risk of post-ICU anxiety and/or Post-Traumatic Stress Disorder. Trial Registration: Clinicaltrials.gov identifier NCT01599689.

Cytokine phenotype, genotype, and renal outcomes at cardiac surgery.

BACKGROUND: Cardiac surgery modulates pro- and anti-inflammatory cytokine balance involving plasma tumour necrosis factor alpha (TNFα) and interleukin-10 (IL-10) together with urinary transforming growth factor beta-1 (TGFß1), interleukin-1 receptor antagonist (IL1ra) and tumour necrosis factor soluble receptor-2 (TNFsr2). Effects on post-operative renal function are unclear. We investigated if following cardiac surgery there is a relationship between cytokine (a) phenotype and renal outcome; (b) genotype and phenotype and (c) genotype and renal outcome. Since angiotensin-2 (AG2), modulates TGFß1 production, we determined whether angiotensin converting enzyme insertion/deletion (ACE I/D) genotype affects urinary TGFß1 phenotype as well as renal outcome. METHODS: In 408 elective cardiac surgery patients we measured pre- and 24 h post-operative urinary TGFß-1, IL1ra and TNFsr2 and pre- and 2 h post-operative plasma TNFα and IL-10. Post-operative responses were compared for each cytokine in patients grouped according to presence or absence of renal dysfunction defined as a drop from baseline eGFR of greater than 25% (as calculated by the method of modification of diet in renal disease (MDRD)) occurring (1) within the first 24 and (2) 48 postoperative hours (early renal dysfunction), (3) on the fifth postoperative day (late renal dysfunction) or (4) at any time throughout the 5 day postoperative period (early and late combined). Patient genotype was determined for TNF/G-308A, TGFß1-509 C/T, IL10/G-1082A and ACE I/D. RESULTS: Post-operative plasma IL-10 and urinary TGFß1 responses were significantly higher in patients who developed early renal dysfunction. IL1ra and TNFsr2 responses were significantly lower 24h post-operatively in patients who developed late renal dysfunction. Genotype did not alter cytokine phenotype or outcome. CONCLUSIONS/INFERENCES: Cytokine profiling may help predict early and late renal dysfunction. Genotypes studied did not alter phenotype or outcome.

Prolonged stay in intensive care unit is a powerful predictor of adverse outcomes after cardiac operations.

BACKGROUND: The aim of this study was to examine the impact of prolonged intensive care unit (ICU) stay on in-hospital mortality and long-term survival. METHODS: Prospectively collected data from 6,101 consecutive patients who underwent surgery between 2003 and 2007 were analyzed. Prolonged ICU stay was defined as a total duration of ICU stay of 3 days or more postoperatively, including readmissions; patients with an ICU stay less than 3 days were identified as controls. Univariate and multiple variable analyses were performed to identify risk factors associated with prolonged ICU stay. RESULTS: Of 6,101 patients, 1,139 (18.7%) patients had a prolonged ICU stay. These patients had a higher ICU mortality (10%) compared with controls (0.6%; p < 0.001). On discharge from the ICU, their hospital mortality was still 6-fold higher (1.2%) compared with controls (0.2%; p < 0.001). Finally, the patients who had prolonged ICU stays had lower survival after discharge from the ICU-89.2% and 81.2% at 1 year and 3 years, respectively, compared with 97.8% and 93.6%, respectively, for controls (p < 0.001). Multiple variable analysis revealed prolonged ICU stay to be an independent predictor of prolonged hospital stay, higher hospital mortality, and poorer long-term survival (all p < 0.001). CONCLUSIONS: Prolonged ICU stay is an important predictor of adverse immediate, short-term, and long-term outcomes after cardiac operations.

Circulatory arrest versus cerebral perfusion during pulmonary endarterectomy surgery (PEACOG): a randomised controlled trial.

BACKGROUND: For some surgical procedures to be done, a patient's blood circulation needs to be stopped. In such situations, the maintenance of blood flow to the brain is perceived beneficial even in the presence of deep hypothermia. We aimed to assess the benefits of the maintenance of antegrade cerebral perfusion (ACP) compared with deep hypothermic circulatory arrest (DHCA). METHODS: Patients aged 18-80 years undergoing pulmonary endarterectomy surgery in a UK centre (Papworth Hospital, Cambridge) were randomly assigned with a computer generated sequence to receive either DHCA for periods of up to 20 min at 20°C or ACP (1:1 ratio). The primary endpoint was change in cognitive function at 12 weeks after surgery, as assessed by the trail-making A and B tests, the Rey auditory verbal learning test, and the grooved pegboard test. Patients and assessors were masked to treatment allocation. Primary analysis was by intention to treat. The trial is registered with Current Controlled Trials, number ISRCTN84972261. FINDINGS: We enrolled 74 of 196 screened patients (35 to receive DHCA and 39 to receive ACP). Nine patients crossed over from ACP to DHCA to allow complete endarterectomy. At 12 weeks, the mean difference between the two groups in Z scores (the change in cognitive function score from baseline divided by the baseline SD) for the three main cognitive tests was 0·14 (95% CI -0·14 to 0·42; p=0·33) for the trail-making A and B tests, -0·06 (-0·38 to 0·25; p=0·69) for the Rey auditory verbal learning test, and 0·01 (-0·26 to 0·29; p=0·92) for the grooved pegboard test. All patients showed improvement in cognitive function at 12 weeks. We recorded no significant difference in adverse events between the two groups. At 12 weeks, two patients had died (one in each group) [corrected]. INTERPRETATION: Cognitive function is not impaired by either ACP or DHCA. We recommend circulatory arrest as the optimum modality for patients undergoing pulmonary endarterectomy surgery. FUNDING: J P Moulton Charitable Foundation.