Difficult intubation rare in caesarean delivery under general anaesthesia in Singapore

One in 20 local obstetric patients delivering by caesarean section go through a difficult intubation, but none of them has had any failure of intubation, reports a Singapore study.

“The true incidence of difficult intubation was likely to be lower, as 90.1 percent of intubations were performed by junior residents,” the researchers said. “As the frequency of obstetric general anaesthesia is declining, there is a need to provide residents with every opportunity possible to manage the obstetric airway under appropriate supervision.”

Pregnant women who underwent caesarean delivery under general anaesthesia from 2013 to 2016 were included in this study. The researchers reviewed their medical records to extract relevant data.

Difficult intubation was defined as “requiring more than one attempt at intubation or documented as such, based on the opinion of the anaesthetist,” while a failed intubation referred to an “inability to intubate the trachea, with subsequent abandonment of intubation as a means of airway management.”

A total of 660 caesarean delivery under general anaesthesia were identified. These women had a mean age of 32.1 years, with a median body mass index of 27.5 kg/m². All patients had rapid sequence induction with cricoid pressure, of whom 91.2 percent had been administered thiopentone and 98.1 percent succinylcholine. [Singapore Med J 2022;63:152-156]

Thirty-three difficult intubations occurred, yielding a 5.0-percent incidence. Most of the intubations (90 percent), as well as difficult intubations (28 out of 33, 84.8 percent) were carried out by junior trainees. Repeat intubations were done by senior residents/fellows (57.1 percent) and consultants (14.3 percent). No incidence of failed intubation transpired.

“The frequency of general anaesthesia for caesarean delivery at our institution has declined from 20.4 percent in the early 2000s to 4.5 percent in the present study, in line with global trends,” the researchers said. [Int J Obstet Anesth 2004;13:221-226; Anaesthesia 2003;58:1114-1118]

“Similar to the indications elsewhere, general anaesthesia was administered mainly in emergency settings to facilitate expeditious delivery or when regional anaesthesia was contraindicated,” they added.

Performance barometer

Of note, the incidence of difficult intubation was higher than previously reported, but the definition of difficult intubation was not clearly stated in the earlier study. [Singapore Med J 1992;33:362-364]

Furthermore, the decreased utilization of general anaesthesia for caesarean deliveries could potentially compromise obstetric airway training, according to the researchers. [Anaesthesia 2000;55:179-183; Int J Obstet Anesth 2005;14:2-4; Int J Obstet Anesth 2008;17:233-237]

Statistics on failed or difficult intubation serve as a barometer of trainee performance and is helpful in identifying gaps in supervision. [Anaesthesia 2006;61:192-193]

“The relatively high incidence of difficult intubation observed in our setting could be attributable to the fact that 90.1 percent of intubations had been performed by junior residents,” the researchers said. “The true incidence of difficult intubation is likely lower.”

To address the declining opportunities at managing obstetric general anaesthesia, several studies proposed the use of simulation as a solution. [Int J Obstet Anesth 2001;10:273-277; Simul Healthc 2010;5:320-324; Int J Obstet Anesth 2014;23:341-347]