Insights into Perioperative Cardiac Arrest

A new study that looked at all cardiac arrests that occurred during or shortly after surgery in more than 300 UK hospitals over a year found that this extremely risky and often fatal event occurs in 3 out of every 10,000 procedures that require anesthetic.

The study, the 7th National Audit Project of the Royal College of Anaesthetists (NAP7), was published in Anaesthesia (the journal of the Association of Anaesthetists) and included data from all NHS hospitals as well as some in the independent sector. It was supported by over 11,000 anesthetists across the UK. It is perhaps the broadest and most in-depth investigation of the nature, causes, and consequences of perioperative cardiac arrest, possibly the most dreaded surgical complication by patients, anesthetists, and surgeons. The study comprised a thorough examination of almost 900 instances of perioperative cardiac arrest, 881 of which were included in the study.

Dr Richard Armstrong, Severn School of Anaesthesia and University of Bristol, Bristol, UK, Dr Jasmeet Soar, Consultant in Anaesthesia and Intensive Care, North Bristol NHS Trust, Bristol, UK, and Professor Tim Cook, Consultant in Anaesthesia and Intensive Care Medicine, Royal United Hospitals Bath NHS Trust, Bath, UK and Honorary Professor, School of Medicine, University of Bristol contributed to the two research papers. The whole report is the result of a partnership headed by the Royal College of Anaesthetists (RCoA), and it is also available on the RCoA website.

The authors provide the findings of a 12-month registry that ran from June 2021 to June 2022, with an emphasis on epidemiological and clinical aspects. They examined 881 occurrences of cardiac arrest out of a total yearly caseload of 2.71 million anesthetics, yielding an incidence of 3 per 10,000 anesthetics – lower than previous studies from the United States (5.7 per 10,000) and Brazil (13 per 10,000).

The incidence varies according to the patient and surgical variables. Patients who suffered this cardiac condition were more likely to be male (56%), but only 42% of all procedures were in men. The extremely old and very young were also at increased risk: 25% of cardiac arrests happened in adults over 75 years old, although only 13% of patients were in this age group; and 8% of cardiac arrests occurred in children under 1 year old, while only 1% of total patients were in this age group.

Patients who suffered cardiac arrest were more likely to be receiving emergency surgery than the general population undergoing anesthesia (65% of cardiac arrests happened during emergency surgery but only 30% of all cases were emergency). Similarly, 60% of cardiac arrests occurred during complex surgery, despite the fact that only 28% of cases were classified as complex. The timing of the operation was also important: 14% of cardiac arrests occurred on weekends (Saturday/Sunday), although only 11% of all surgeries occurred on weekends; and 19% of cardiac arrests occurred after hours (1801H-0759H), whereas only 10% of all surgeries occurred after hours.

The most cardiac arrests occurred during orthopedic trauma surgery (12%), major abdominal surgery (10%), cardiac surgery (9%), and vascular surgery (8%). When adjusted for the annual caseload in each profession, cardiac surgery (9-fold excess risk), cardiology operations requiring anesthetic care (8-fold), and vascular surgery (4-fold) had the highest risk of cardiac arrest.

Major bleeding (17% of cardiac arrests), very slow heart rate (9%), and cardiac ischemia (lack of oxygen given to the heart) (7% of cardiac arrests) were the most common causes of cardiac arrest. The authors investigated whether the cardiac arrest was caused by the patient’s chronic and present illness or by anesthesia or surgery, discovering that the patient’s condition played a crucial role in 82% of instances, anesthesia in 40%, and surgery in 35%. Frailty, severe underlying disease, and bleeding are examples of patient factors; complex surgery complicated by bleeding is an example of a surgical factor; and a severe allergic reaction to prescribed medicines is an example of an anesthesia factor.

The authors explain that the study data “highlight a complex interaction of patient, surgical and anesthetic factors in many perioperative cardiac arrests” also noting that “the cause of cardiac arrest varied widely in different surgical specialties.” The study also showed high rates of senior staff involvement in cases of cardiac arrest.

The study found that cardiac arrest was rare in healthy (ASA physical status 1) patients undergoing routine surgery, with this event occurring in fewer than 1 in 10,000 cases and mortality occurring in 1 in 132,000.

The finding that in more than 80% of all cases, and three-quarters of those occurring at night, a consultant was present during induction of anaesthesia in those cases that had a cardiac arrest suggests efforts to match clinical staffing to patient and case complexity and risk. When a consultant was not present, another senior anaesthetist able to work autonomously was commonly involved.”

Professor Tim Cook, Consultant in Anaesthesia and Intensive Care Medicine, Royal United Hospitals Bath NHS Trust, Bath, UK and Honorary Professor, School of Medicine, University of Bristol, UK

Outcomes after perioperative cardiac arrest

The second paper focuses on the outcomes of patients who experienced perioperative cardiac arrest.

Rates of effective resuscitation were much greater in perioperative cardiac arrests than in cardiac arrests that occurred outside of the hospital or in hospitals in other settings such as a hospital ward. 665 of the 881 patients who experienced a cardiac arrest were successfully resuscitated, and 384 (52%) of the 742 patients whose hospital prognosis was recorded survived. The modified Rankin score (mRS) was used to assess the extent to which those who were released had a strong functional recovery in 284 survivors, with 249 (88%) having a good functional score (0-3).

Patient age, pre-existing health, surgical specialty, heart rhythm upon cardiac arrest, and duration of resuscitation were all factors that influenced the extent of resuscitation success. Patients at the extremes of age fared poorly, with 40% of patients over 75 years old surviving and 45% of babies under one-month-old surviving. When surgery was urgent, hospital survival was also lower, with 88% of patients receiving normal surgery and 37% of emergency cases surviving to discharge.

In 31% of cases, death was determined to be an unavoidable process. The overall quality of care was good, with care during and after cardiac arrest rated as good in 80% of cases and bad in less than 2%. However, 32% of patients included characteristics of poor care before to cardiac arrest, which are a focus of potential to improve care.

Dr Soar says: “As patients undergoing surgery have become older and less healthy in the last decade, and surgical care has ever more to offer, it is inevitable that major complications, including cardiac arrest will occur. It is clear from this study that outcomes from perioperative cardiac arrests are substantially better than from other causes of cardiac arrest. Most patients survive the cardiac arrest and of those who go home the vast majority make a good recovery.”

Professor Cook adds: “It is notable that 80% of patients were successfully resuscitated and more than half managed to leave the hospital. To put this in context, only 23% of patients who have a cardiac arrest elsewhere in hospital survive to leave and fewer than 10% of patients who have a cardiac arrest outside hospital are alive a month later. The higher survival rate is likely to be contributed to by being in a highly monitored environment and attended by a trained anesthetist who can rapidly identify and respond to the causes of the cardiac arrest.”

Dr Armstrong concludes: “This study is important for clinicians and patients. For clinicians, it provides a unique insight into the frequency, causes, contributing factors, and outcomes of perioperative cardiac arrest. There are also areas identified for improvement. For patients, the project provides a rich resource of information which can be used to better inform them, so they can understand the risks and benefits of undergoing surgery and interventional procedures requiring anesthesia.”

Dr Fiona Donald, President of the Royal College of Anaesthetists said: “For the first time, we have a clear, comprehensive and detailed picture of perioperative cardiac arrest in all NHS hospitals in the UK. Several million patients undergo surgery each year and this research shows they can have confidence that their risk of cardiac arrest is very low. For the 1 in 3,000 patients who do experience it, the quality of care is high.

“NAP7 has huge potential to drive improvements in perioperative care. Alongside the wealth of in-depth data, the report also includes practical and accessible recommendations that will help us improve the prevention and treatment of perioperative cardiac arrest.”

It should be noted that this publication includes the results of NAP7, which will be published in full on November 17, 2023. The Royal College of Anaesthetists’ National Audit Projects investigate rare but possibly catastrophic anesthesia problems. They are given by the Royal College of Anaesthetists’ Centre for Research and Improvement and are meant to evaluate, report on, and stimulate improvements in practice. Each NAP focuses on a different issue that is relevant to both patients and anesthetists. NAP7 investigates postoperative cardiac arrest.

Source: AAGBI

For more information: Perioperative cardiac arrest: epidemiology and clinical features of patients analyzed in the 7th National Audit Project of the Royal College of Anaesthetists. Anaesthesia. 

doi.org/10.1111/anae.16156.