Perioperative cardiac arrest

Résumé fourni par la source

Perioperative cardiac arrest (POCA) is a rare but potentially catastrophic complication during surgery and anaesthesia, and is associated with high rates of mortality and morbidity. It differs from most in-hospital cardiac arrests due to the highly monitored nature of the perioperative period, and has distinct causative and contributory factors related to the patient, surgery, and anaesthetic. This review highlights the definition, aetiology, and management of POCA, and describes those factors important for improving perioperative safety. There is no unifying or standard definition for POCA, and this contributes to the variation in the incidence reported in the literature. The key elements to the definition are the cardiac arrest itself, and the ‘perioperative’ period. The 7th National Audit Project of the Royal College of Anaesthetists (NAP7), a national cohort study, defined POCA as the need for cardiopulmonary resuscitation (CPR) that consisted of at least five chest compressions and/or defibrillation, and the perioperative period as beginning with first hands-on contact with an anaesthetist at the start of anaesthesia and ending 24 h after the recovery handover or at hospital discharge, whichever occurred first1. Other studies have focused solely on the intraoperative phase or included longer periods of follow-up. The NAP7-reported overall incidence of POCA was 3/10 000 anaesthetics2, a figure consistent with other international estimates that range from 2 to 13/10 0003–5. Despite the severity of these events, outcomes are generally better than most other in-hospital cardiac arrests due to the close monitoring and immediate access to expert resuscitation. In NAP7, 75.5% of patients with POCA achieved a return of spontaneous circulation (ROSC) and 52.5% survived to hospital discharge, although survival varied depending on the cause of arrest6. Crucially, the majority of those discharged alive had a favourable functional outcome. The risk of POCA is determined by a combination of patient, surgical, and anaesthetic factors. Patient factors include extremes of age, with infants and the elderly being at highest risk. Both chronic co-morbidities and any acute condition requiring surgery contribute, both of which are reflected by an increase in ASA physical status classification. Obesity has a range of impacts, particularly for airway and breathing-related complications, and frailty appears to act as a risk multiplier alongside age. Emergency surgery carries increased risk of POCA compared to elective procedures, as does increasing severity of procedure. Certain specialties have higher rates of POCA, for example cardiac and vascular surgery (Fig. 1). Procedures under general anaesthetic tend to be higher risk than those under regional or local anaesthesia, but this, and several of the other factors mentioned, are confounded by indication and clinical complexity. Relative risk of cardiac arrest by surgical specialty in NAP7 Relative risk calculated as proportion of cardiac arrest cases divided by proportion of surgical activity. A value greater than one infers that a specialty was overrepresented in cardiac arrest cases. The aetiology of POCA differs from other in-hospital arrests. The most common reported causes in NAP7 overall were major haemorrhage (16.9%), bradyarrhythmia (9.4%), and cardiac ischaemia (7.4%). There was, however, significant variation by specialty: for example, major haemorrhage was the leading case in vascular surgery, cardiac ischaemia in cardiac surgery, septic shock in general surgery, and bradyarrhythmia (related to vagal stimulation) in gynaecological surgery. The majority of events occur during surgery itself or between induction of anaesthesia and the start of the procedure (Fig. 2), although around a quarter were reported to be postoperative2. Most cardiac arrests were judged to have multiple contributing factors including patient factors (co-morbidity and disease process) in 81.6%, anaesthesia in 39.8%, and surgical in 35.3%. Surgery alone was judged to contribute 5.4% of cardiac arrests. Perioperative phase of cardiac arrest events reported to NAP7 Although standard Advanced Life Support (ALS) guidelines provide a framework for resuscitation in the perioperative setting, context-specific modifications may be required7. Depending on the cause, it may be necessary to work in parallel to treat a specific, reversible cause during cardiopulmonary resuscitation, for example the control of surgical bleeding or airway control. This may require pauses in chest compression to enable treatment of the underlying cause. Current ALS guidelines recommend that chest compressions should be started when systolic blood pressure remains under 50 mmHg despite initial interventions, and the initial doses of intravenous adrenaline should be titrated small doses (for example 50–100 mcg) rather than the standard ALS adrenaline bolus dose of 1 mg in adults8. Although there is no specific risk assessment tool for POCA, other generic scoring tools (for example the Surgical Outcome Risk Tool; https://www.sortsurgery.com/) do associate with the risk of POCA. Whereas in the majority of patients the absolute risk of POCA and death is small, the increased relative risk may be an important risk for some patients. A common fear of patients having surgery is ‘will I wake up after my operation?’9 Reassuringly, in low-risk (ASA 1 or 2) patients the risk of cardiac arrest was about 1/8500 cases, and the risk of death about 1/95 000 cases (Table 1). The majority of POCAs occur in higher-risk patients having higher-risk procedures. Risk of perioperative cardiac arrest and death in different patient groups Numbers are approximate for ease of presentation. Older, frailer patients are aged >65 years and Clinical Frailty Score ≥5 Risk of perioperative cardiac arrest and death in different patient groups Numbers are approximate for ease of presentation. Older, frailer patients are aged >65 years and Clinical Frailty Score ≥5 An often-overlooked issue in the perioperative period is the management of do not attempt CPR (DNACPR) recommendations or Advance Directives. Although the number of people affected is increasing, most are based on the person having a cardiac arrest in the community or ward settings where the chances of survival after cardiac arrest are considerably less than in the closely monitored anaesthetic setting. Guidelines from the Association of Anaesthetists suggest it is usually appropriate to suspend a DNACPR recommendation during the perioperative period, although the key emphasis is on early discussions with patients to achieve shared understanding and agreed aims10. Patients may want surgery to relieve symptoms but not wish to be resuscitated or receive prolonged postoperative critical care. These wishes need to be documented, respected, shared during the preoperative team brief, and used to inform which interventions are appropriate if cardiac arrest occurs. For example, a patient might accept CPR for an easily reversible cause if it returned them to their baseline healthy state but would not wish a prolonged period of intensive care and multiple organ support following ROSC. Effective team working and communication are crucial in the management of POCA, facilitated by standardized tools such as the WHO Surgical Safety Checklist and other cognitive aids, particularly in crisis situations. In NAP7, a major haemorrhage occurred in about 1% of all operations requiring anaesthesia, and when cardiac arrest occurred over half of patients died. A common theme was the need for a practiced major haemorrhage protocol, effective early clear communication between the surgeon and anaesthetist to achieve haemorrhage control, the rapid availability of blood and blood products, and use of near-patient coagulation tests to guide their use. POCA can be a traumatic event for clinicians and have a negative impact on confidence as well as both professional and persona

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