A recent study, possibly the largest of its kind, examining all cardiac arrests occurring during or soon after surgery in more than 300 UK hospitals over 12 months, has identified that this often fatal event happens in three per 10 000 surgeries requiring anaesthesia.
The study – the 7th National Audit Project of the Royal College of Anaesthetists (NAP7) published in Anaesthesia (the journal of the Association of Anaesthetists) – included data from all NHS hospitals and some in the independent sector and received the support of more than 11 000 anaesthetists throughout Britain.
It is the most in-depth study of the nature, causes and consequence of perioperative cardiac arrest, the complication of surgery most feared by patients, anaesthetists and surgeons, reports News-Medical.Net.
It included detailed review of more than 900 cases of perioperative cardiac arrest, of which 881 were included in the research.
The authors report the results of the 12-month registry, from June 2021 to June 2022, focusing on epidemiology and clinical features. They reviewed 881 cases of cardiac arrest among an annual caseload of 2.71m anaesthetics, giving an incidence of three per 10 000 anaesthetics – lower than other studies from the USA (5.7 per 10 000) and Brazil (13 per 10 000) had estimated.
Incidence varied with patient and surgical factors. Compared with all surgeries, patients who had cardiac arrest were more frequently male (56%), while only 42% of all surgeries were in men. Increased risk was also shown for the very old and very young: 25% of cardiac arrests occurred in people over 75, while only 13% of patients were in this age group; and 8% of cardiac arrests occurred in children aged under one year, while only 1% of total patients were in this age group.
Compared with the overall population undergoing anaesthesia, those experiencing cardiac arrest were more often ill or had other significant medical conditions and were less often healthy.
Patients who were ill or had significant medical conditions (ASA physical status 4–5) accounted for 37% of cardiac arrests but only 4% of the surgical population, whereas healthy patients (ASA physical status 1-2) accounted for 26% of those who had a cardiac arrest and 73% of the surgical population.
Compared with the overall population undergoing anaesthesia, patients who had cardiac arrest were more likely to be undergoing emergency surgery (65% of cardiac arrests occurred during emergency surgery but only 30% of all cases were emergency).
Similarly, 60% of the cardiac arrests happened during complex surgery while only 28% of cases were classed as complex.
Timing of surgery also mattered: 14% of cardiac arrests occurred during the weekend (Saturday/Sunday), while only 11% of all surgeries were during the weekend; and 19% of cardiac arrests occurred out-of-hours, while only 10% of all surgeries were out of hours.
The highest number of cardiac arrests occurred during orthopaedic trauma surgery (12% of all cardiac arrests), major abdominal surgery (10%), cardiac surgery (9%) and vascular surgery (8%). When adjusted for the annual caseload in each specialty, those with the highest risk of cardiac arrest were cardiac surgery (nine-fold excess risk), cardiology procedures requiring anaesthetic care (eight-fold) and vascular surgery (four-fold).
The most common causes of cardiac arrest were major bleeding (causing 17% of cardiac arrests), very slow heart rate (9%), and cardiac ischaemia (lack of oxygen delivered to the heart) (7%).
The authors explored whether the cardiac arrest was due to underlying patient chronic and current ill health or due to anaesthesia or surgery, finding that key factors were the patient's condition in 82% of cases, anaesthesia in 40% and surgery in 35%.
Examples of patient factors include frailty, severe underlying disease and bleeding; examples of surgical factors include complex surgery complicated by bleeding; and anaesthesia examples include a severe allergic reaction to administered drugs.
The authors said the study data “highlight a complex interaction of patient, surgical and anaesthetic 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.
Reassuringly, in healthy (ASA physical status 1) patients undergoing routine surgery, the study showed the rarity of cardiac arrest, with this event occurring in fewer than one in 10 000 cases and death in one 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,” said Professor Tim Cook, Consultant in Anaesthesia and Intensive Care Medicine, Royal United Hospitals Bath NHS
Trust, and honorary professor, University of Bristol.
Outcomes after perioperative cardiac arrest
The second paper addresses the outcomes for patients who had a perioperative cardiac arrest.
Rates of successful resuscitation were notably higher for perioperative cardiac arrest than is achieved in cardiac arrests that take place out of hospital or in hospitals in other settings, like a hospital ward.
Among 881 patients who had a cardiac arrest, 665 were successfully resuscitated and of 742 in whom their hospital outcome was known, 384 (52%) had survived. The extent to which those who were discharged made a good functional recovery was reported in 284 survivors using a scale called the modified Rankin score (mRS), with 249 (88%) having a good functional score (0-3).
Multiple factors influenced the extent of success of resuscitation, including patient age, pre-existing health, surgical specialty, the heart rhythm at cardiac arrest and duration of resuscitation. Survival to hospital discharge was worse in patients at the extremes of age with 40% of patients aged over 75 and 45% of babies aged under four weeks surviving.
Hospital survival was also poorer when surgery was urgent, with 88% patients undergoing routine surgery and 37% of emergency cases surviving to discharge.
When death occurred, it was judged to be an unpreventable process in 31% of cases. The quality of care was generally good with care during and after cardiac arrest judged good in 80% and poor in fewer than 2%.
However, elements of poor care before cardiac arrest were identified in 32% of cases and are a focus of opportunities to improve care.
Study details
Peri-operative cardiac arrest: epidemiology and clinical features of patients analysed in the 7th National Audit Project of the Royal College of Anaesthetists
R. Armstrong, J. Soar, A. Kane, S. Kendall, et al.
Published in Anaesthesia on 16 November 2023
Summary
The 7th National Audit Project of the Royal College of Anaesthetists studied peri-operative cardiac arrest in the UK, a topic of importance to patients, anaesthetists and surgeons. Here we report the results of the 12-month registry, from 16 June 2021 to 15 June 2022, focusing on epidemiology and clinical features. We reviewed 881 cases of peri-operative cardiac arrest, giving an incidence of 3 in 10,000 anaesthetics (95%CI 3.0–3.5 per 10,000). Incidence varied with patient and surgical factors. Compared with denominator survey activity, patients with cardiac arrest: included more males (56% vs. 42%); were older (median (IQR) age 60.5 (40.5–80.5) vs. 50.5 (30.5–70.5) y), although the age distribution was bimodal, with infants and patients aged > 66 y overrepresented; and were notably more comorbid (73% ASA physical status 3–5 vs. 27% ASA physical status 1–2). The surgical case-mix included more weekend (14% vs. 11%), out-of-hours (19% vs. 10%), non-elective (65% vs. 30%) and major/complex cases (60% vs. 28%). Cardiac arrest was most prevalent in orthopaedic trauma (12%), lower gastrointestinal surgery (10%), cardiac surgery (9%), vascular surgery (8%) and interventional cardiology (6%). Specialities with the highest proportion of cases relative to denominator activity were: cardiac surgery (9% vs. 1%); cardiology (8% vs. 1%); and vascular surgery (8% vs. 2%). The most common causes of cardiac arrest were: major haemorrhage (17%); bradyarrhythmia (9%); and cardiac ischaemia (7%). Patient factors were judged a key cause of cardiac arrest in 82% of cases, anaesthesia in 40% and surgery in 35%.
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