Peri-operative SARS-CoV-2 infection increases postoperative mortality. The aim of this study was to determine the optimal duration of planned delay before surgery in patients who have had SARS-CoV-2 infection. This international, multicentre, prospective cohort study included patients undergoing elective or emergency surgery during October 2020. Surgical patients with pre-operative SARS-CoV-2 infection were compared with those without previous SARS-CoV-2 infection. The primary outcome measure was 30-day postoperative mortality. Logistic regression models were used to calculate adjusted 30-day mortality rates stratified by time from diagnosis of SARS-CoV-2 infection to surgery. Among 140,231 patients (116 countries), 3127 patients (2.2%) had a pre-operative SARS-CoV-2 diagnosis. Adjusted 30-day mortality in patients without SARS-CoV-2 infection was 1.5% (95%CI 1.4-1.5). In patients with a pre-operative SARS-CoV-2 diagnosis, mortality was increased in patients having surgery within 0-2 weeks, 3-4 weeks and 5-6 weeks of the diagnosis (odds ratio (95%CI) 4.1 (3.3-4.8), 3.9 (2.6-5.1) and 3.6 (2.0-5.2), respectively). Surgery performed ≥ 7 weeks after SARS-CoV-2 diagnosis was associated with a similar mortality risk to baseline (odds ratio (95%CI) 1.5 (0.9-2.1)). After a ≥ 7 week delay in undertaking surgery following SARS-CoV-2 infection, patients with ongoing symptoms had a higher mortality than patients whose symptoms had resolved or who had been asymptomatic (6.0% (95%CI 3.2-8.7) vs. 2.4% (95%CI 1.4-3.4) vs. 1.3% (95%CI 0.6-2.0), respectively). Where possible, surgery should be delayed for at least 7 weeks following SARS-CoV-2 infection. Patients with ongoing symptoms ≥ 7 weeks from diagnosis may benefit from further delay.

SARS-CoV-2 has been associated with an increased rate of venous thromboembolism in critically ill patients. Since surgical patients are already at higher risk of venous thromboembolism than general populations, this study aimed to determine if patients with peri-operative or prior SARS-CoV-2 were at further increased risk of venous thromboembolism. We conducted a planned sub-study and analysis from an international, multicentre, prospective cohort study of elective and emergency patients undergoing surgery during October 2020. Patients from all surgical specialties were included. The primary outcome measure was venous thromboembolism (pulmonary embolism or deep vein thrombosis) within 30 days of surgery. SARS-CoV-2 diagnosis was defined as peri-operative (7 days before to 30 days after surgery); recent (1-6 weeks before surgery); previous (≥7 weeks before surgery); or none. Information on prophylaxis regimens or pre-operative anti-coagulation for baseline comorbidities was not available. Postoperative venous thromboembolism rate was 0.5% (666/123,591) in patients without SARS-CoV-2; 2.2% (50/2317) in patients with peri-operative SARS-CoV-2; 1.6% (15/953) in patients with recent SARS-CoV-2; and 1.0% (11/1148) in patients with previous SARS-CoV-2. After adjustment for confounding factors, patients with peri-operative (adjusted odds ratio 1.5 (95%CI 1.1-2.0)) and recent SARS-CoV-2 (1.9 (95%CI 1.2-3.3)) remained at higher risk of venous thromboembolism, with a borderline finding in previous SARS-CoV-2 (1.7 (95%CI 0.9-3.0)). Overall, venous thromboembolism was independently associated with 30-day mortality ). In patients with SARS-CoV-2, mortality without venous thromboembolism was 7.4% (319/4342) and with venous thromboembolism was 40.8% (31/76). Patients undergoing surgery with peri-operative or recent SARS-CoV-2 appear to be at increased risk of postoperative venous thromboembolism compared with patients with no history of SARS-CoV-2 infection. Optimal venous thromboembolism prophylaxis and treatment are unknown in this cohort of patients, and these data should be interpreted accordingly.

Explain the Sternbach and Hunter criteria for diagnosing serotonin syndrome. Describe the wide variety of signs and symptoms of serotonin syndrome. Distinguish the pathophysiology of serotonin syndrome. Summarise the principles of management of a patient with serotonin syndrome.The serotonin syndrome (SS) is a potentially life-threatening drug interaction caused by excessive serotoninergic activity in the CNS. It can arise from therapeutic drug use, drug interactions, or intentional overdose of medications that affect the serotonergic system. The clinical features of SS have been described as a triad of changes in mental status, neuromuscular abnormalities, and autonomic hyperactivity. 1 Clinical presentation is highly variable, and ranges from mild symptoms to a severe life-threatening condition. The first human case reports of serotonin-related adverse effects of psychotropic drugs were published in the 1950s. The term serotonin syndrome was first used in the early 1980s to describe the presence of hyperthermia and behavioural changes in patients receiving medications that have serotoninergic activity. 2 Diagnosis during the perioperative period is particularly challenging because many confounding factors can obscure the clinical picture. In addition, other conditions, such as malignant hyperthermia and neuroleptic malignant syndrome, have similar features to SS, and are part of the differential diagnosis of delirium and neuromuscular abnormalities during the perioperative period. Many agents with potential serotoninergic activity are given during relatively short periods of time in the perioperative period. This increases the likelihood for drug interactions and their consequences, such as the SS.In this article, we review the epidemiology, diagnostic challenges, and management of perioperative SS. In addition, Ashish Bartakke FRCA EDAIC is a senior clinical fellow in cardiothoracic anaesthesia and critical care who has special interests in cardiothoracic anaesthesia, cardiopulmonary exercise testing, and pain management.Carlos Corredor FRCA FFICM is a consultant in cardiothoracic anaesthesia and intensive care whose interests include anaesthesia for major aortovascular surgery, mechanical circulatory support, and perioperative echocardiography.Adriaan van Rensburg FCA (SA) MMED (ANES) MD FRCPC is an associate professor in anaesthesiology at the University of Toronto. Dr van Rensburg has clinical and research interests in cardiovascular and transplant anaesthesia and perioperative ultrasound. He is the Chair for the annual meeting of the Canadian Anaesthesiologists' Society. Key pointsSerotonin syndrome has been described as a triad of changes in mental status, neuromuscular abnormalities, and autonomic hyperactivity. It is difficult to diagnose serotonin syndrome in a patient under general anaesthesia because the signs and symptoms are similar to other perioperative conditions. Concurrent use of antidepressants has been strongly associated with the occurrence of serotonin syndrome. The Hunter criteria for pre...

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