There’s a whole herd of ‘holy cows’ in anaesthesia. Practices we have despite total lack of evidence, that are so holy that we are afraid to discuss them. It seems to take few decades and a generational shift before they are seriously challenged.
Cricoid pressure was one of those holy cows that only after decades was sent packing into oblivion.
It is hard to tell which cow that is due next for the house on the hill but it seems our current thinking around intubating women for caesareans in general anaesthesia is a prime candidate.
For ages we have been rapid sequence intubating women who are due for general anaesthesia for caesareans. We did this because we thought they were more prone to aspirations. With good reason. Back in the days there was horrendous mortality of aspirational pneumonias in obstetric anaesthesia.
We decided something had to be done and one of the many countermeasures we implemented was the RSI with cricoid pressure. As a result of our attention the mortality dwindled. Between 1995 and 2005 there were only two reported cases of death due to aspirational pneumonia in women undergoing caesarean.
So we had won. But how? Who cares? No-one wants to change a winning concept. RSI became one of the many unproven tenets that we never cared or dared to challenge. Despite there being heaps of other factors that could explain the reduction like implementing fasting regimes, better information, pharmacological prophylaxis, better supervision and what not.
Until now, that is. In a time where RSI and cricoid pressure is under siege researchers have looked closer at caesareans in general anaesthesia. They’re asking ‘do we really need to RSI fasting, healthy pregnant women who are due for caesareans? Do they even need a tube?’
They make some observations.
- The general risk of aspiration in fasting patients undergoing general anesthesia is 1 in 3000-4000 patients.
- Huge retrospective studies tell us pregnancy is not an independent predictor of pulmonary aspiration.
- This could be explained by other studies that demonstrate pregnant women, obese or of normal weight, who are not in labor show the same rates of gastric emptying as non-pregnant women. Contrary to common knowledge.
- There is indeed a higher rate of gastroesophageal reflux but that can be efficiently managed by pharmacological means.
So, given that there is no reduced gastric emptying or elevated risk of aspiration. Then we should be able to safely do cesareans in GA with only a LMA for airway control. Right?
Indeed, one study from 2010 (Halasseh, Sukkar, Hassan et al) does just that. It looks at 3000 fasting, healthy women undergoing elective caesareans in GA with a LMA. No RSI, no tube and no cricoid pressure.
The results are pretty convincing. In a series of 3000 patients there was only one regurgitation and no aspirations pneumonias.
In the same issue of BJA professor M.J. Paech writes an editorial commentary on the study that is also a good read. He remains conservative but concludes with
‘The cow is on the move but should not be sent packing just yet!’