GA sections - polls from DAS 2022

| Moon-Moon Majumdar | Nuala Lucas |

At DAS 2022 we polled attendees on their routine practice of obstetric GA, and we present the results here.

Oxygenation

A variety of strategies are available to support pre-oxygenation. Face mask breathing until EtO2 is >0.9 was stated as the preferred technique by 46% of delegates. Interestingly the percentage of those using high flow nasal oxygen (HFNO) to pre-oxygenate (14%) is the same as those using tidal volume breathing for 3 minutes (14%). There is evidence in nonobstetric patients with obesity that HFNO, when used as a technique for preoxygenation and apnoeic oxygenation during rapid sequence induction (RSI), can prolong the apnoeic period.1 In pregnant women, there is no evidence of benefit of HFNO as a preoxygenation tool.2 However, one small study did suggest that it can confer benefit when used during the apnoeic period of RSI, as assessed by the surrogate marker of arterial PaO2 immediately after intubation.3 It is noteworthy that this study was confined to elective GA for caesarean section in patients with a normal BMI.

23% of DAS 2022 attendees routinely use apnoeic oxygenation during obstetric GA, with just 17% of attendees stating they never use it. In non-obstetric patients, there have been two interesting studies investigating THRIVE. One demonstrated a prolonged apnoea time in the HFNO THRIVE group compared to the facemask preoxygenation group,4 and the other demonstrated increased incidence of desaturation below 93% in the facemask group compared to the THRIVE group. 5 However, a clinical trial has yet to be undertaken in obstetric patients.6

Drugs

The majority of delegates (58%) are now using rocuronium as compared to 40% still using suxamethonium. This shift to rocuronium in obstetrics has been slow, in contrast to nonobstetric practice. There is debate around time to- and quality of- intubating conditions, incidence of anaphylaxis between suxamethonium and rocuronium, and the cost of sugammadex. However, as it becomes more evident that adequate paralysis is importance for optimising first-pass intubation success and effective facemask ventilation7 (facemask ventilation is crucial as part of the OAA-DAS guidelines8 to ensure rescue oxygenation), it is likely that rocuronium will continue to increase in acceptance.

Most attendees routinely use opioids at induction (42%), with 24% sometimes using opioids and 21% rarely using opioids. Just 13% never use opioids at induction. That 13% of respondents never use opioids at induction is perhaps surprising. The use of opioids at induction has a vital role in minimising the hypertensive response to laryngoscopy,

particularly relevant in patients with hypertensive disorders of pregnancy and also in reducing the risk of accidental awareness. A recent meta-analysis found no difference in neonatal Apgar scores with remifentanil and alfentanil use at induction of GA.9

Laryngoscopy

54% of attendees use videolaryngoscopy as the first line intubating device for obstetric GA and 27% stated this practice has developed over the last year. For 40% of attendees, videolaryngoscopy is their Plan B. Provided the anaesthetist is appropriately trained, there is now compelling evidence that videolaryngoscopy provides improved laryngeal view and higher rates of successful intubation.10

Conclusion

From this snapshot, it seems that practice for obstetric GA is slowly changing in-line with best evidence available and to become more consistent with RSI in non-obstetric practice. There are important gaps in our knowledge, and further investigation – particularly into apnoeic oxygenation in parturients – is crucial.

Link to references