Amanda Pinder (Leeds General Infirmary), David Milne (Leeds General Infirmary), Heather Gorton (Leeds General Infirmary), Marian Knight (NPEU)
Severe maternal morbidity and mortality
Obstetric Anaesthetists Association
Reports from the Confidential Enquiries into Maternal Deaths have shown a decrease in the number of anaesthetic related deaths over recent years.
However, a consistent cause of deaths is hypoxia relating to a failure to intubate and ventilate.
The incidence of failed intubation for general anaesthesia among the pregnant population is estimated to be up to eight times that of the non-pregnant population, however, there are no national data in the UK.
Concerns about the risk of the condition when emergency obstetric anaesthesia is required may be associated with a move to planned elective surgery.
The aims of this study were to calculate the national incidence of failed intubation in obstetric general anaesthesia, to quantify the associated risk factors, and to describe how failed intubation is currently managed in the UK.
The overall incidence was one in 224 general anaesthetics (95% confidence interval (CI) 1 in 179 to 1 in 281).
Failed intubation was associated with obesity, with a 6% increase in the odds of failed intubation with every 1 kg/m2 increase in BMI (adjusted odds ratio (aOR) 1.06, 95% CI 1.00-1.13).
Maternal age (aOR 1.07, 95% CI 1.01-1.14 for every one year increase) and making an assessment of the airway (aOR 3.06, 95% 1.18-7.88 if a Mallampati score was recorded) were also significantly associated.
Management was very variable; the most common rescue procedure was the use of a classical laryngeal mask airway (68% of cases).
There were four cases of gastric aspiration amongst the 57 women with failed intubation (8%), but there were no significant differences in rates of either maternal or neonatal intensive care unit admission amongst cases and controls.
No women died.
The study suggests that the risk of failed intubation is low, but continuing monitoring is important in view of the increasing prevalence of obesity and older maternal age amongst the obstetric population.