New survey data from the 7th National Audit Project of the Royal College of Anaesthetists (NAP7) published in Anaesthesia (the journal of the Association of Anaesthetists) shows that potentially serious complications occur in one in 18 procedures under the care of an anaesthetist.
The risk factors associated with these potentially serious complications include very young age (babies); comorbidities; being male; increased frailty; the urgency and extent of surgery; and surgery taking place at night and/or at weekends.
This paper has been produced by a team of authors across UK hospitals including; Dr Andrew Kane, Consultant in Anaesthesia, James Cook University Hospital, Middlesbrough and Fellow, Health Services Research Centre, Royal College of Anaesthetists, London, UK; Dr Jasmeet Soar, Consultant in Anaesthesia and Intensive Care Medicine, Southmead Hospital, North Bristol NHS Trust, Bristol, UK; and Professor Tim Cook, Consultant in Anaesthesia and Intensive Care Medicine, Royal United Hospitals Bath NHS Foundation Trust, Bath, UK, and Honorary Professor, School of Medicine, University of Bristol, UK.
Complications and critical incidents during anaesthesia, arising due to patient, surgical or anaesthetic factors, may cause harm themselves or progress to more severe events, including cardiac arrest or death. As part of the Royal College of Anaesthetists' 7th National Audit Project, which focuses on peri-operative cardiac arrest, the authors studied a prospective national cohort of unselected patients.
Anaesthetists recorded anonymous details of all cases undertaken over four days at their site through an online survey. Of 416 hospital sites invited to participate, 352 (85%) completed the study. Obstetric cases were analysed separately and will be the focus of a separate paper later. Of 20,996 non-obstetric cases, 1,705 potentially serious complications were reported during 1,150 (5.5%) cases. Circulatory events (such as severely low blood pressure or abnormalities of heart rate and rhythm) accounted for most of these complications [616 (36%)], followed by airway complications (e.g. low oxygen levels) [418 (25%)], metabolic [264 (15%)], breathing (e.g. difficulty in ventilating the lungs) [259 (15%)], 'other' [107 (6%)] and neurological [41 (2%)] events. A single complication was reported in 851 (4%) of total cases, two complications in 166 (1%), and three or more complications in 133 (1%).
In elective surgery, all complications were 'uncommon' (1-10 per 1000 cases) or even less frequent. Emergency (urgent and immediate priority) surgery accounted for 3454 (16%) of the included cases but 714 (42%) of the recorded complications with severe low blood pressure (hypotension), major bleeding, severe alterations in heart rhythm (arrhythmias), septic shock, significant acidosis, and electrolyte (mineral) disturbances all being 'common' (10-100 per 1000 cases).
Complications were associated with very young age (less than 1 year); higher comorbidity as assessed by the American Society of Anesthesiology (ASA) physical status; male sex; increased frailty; urgency and extent of surgery; day of the week (higher risk at weekends); and time of day.
The estimated risk of complications by risk factors were as follows:
Lines with * are the most prominent effects - babies, high ASA ('serious underlying medical issues'), emergency surgery (e.g. bleeding from trauma), operations at night (nearly all emergencies)
*New-born babies (age less than 28 days) (18%) 3.8 times higher risk than young adults (19-25y, 4.7%)
Older adults compared with younger adults (19-25y, 4.7%):
Adults aged 66-75 y – 6.0%, 28% higher risk
Adults aged 76-85 y – 6.1%, 30% higher risk
Adults aged over 85 y - 5.7%, 21% higher risk
*ASA1 (fit and healthy, 3.5%) v ASA 4 (patient with major medical conditions e.g. heart or lung disease, 19%), 5.5 times increased risk for ASA 4 patients
Males (6.4%) v females (4.7%), 40% higher risk for males
Frail (e.g. needing help with daily activities such as cooking, shopping and housework 8.5%) vs. non-frail (4.5%), double the risk for patients who are frail
