Effectiveness of Face mask only oxygenation and apnoeic oxygenation in addition to face mask in sustaining PaO2 during rapid sequence induction - A randomized control trial.

Background and aims: Apnoeic oxygenation, although useful during elective intubations, has not shown consistent beneficial results during emergency intubations in critically ill patients. We aimed to study the effectiveness of adding apnoeic oxygenation to our routine practice of using facemask alone, in emergency laparotomy patients needing rapid sequence induction (RSI), for sustaining partial pressure of oxygen (PaO₂).

Material and methods: Seventy-two patients undergoing RSI for emergency laparotomy were randomly allocated to either receive pre-oxygenation with 5 L/min of oxygen (O₂) with a facemask (Group-FM) or apnoeic oxygenation with 10 L/min of O₂ through a nasal catheter in addition to pre-oxygenation (Group-NC). Apnoea (90 s) was allowed from the removal of the facemask before the resumption of ventilation. Arterial blood gas analysis was done at the baseline, following pre-oxygenation and after 90 s of apnoea to study the PaO₂ and partial pressure of carbon dioxide (PaCO₂). The circuit O₂ concentrations (fraction of inspired [FiO₂] and end-tidal [EtO₂]) were also noted to ensure a steady state of O₂ uptake was reached.

Results: The circuit O₂ concentrations were 90 ± 4% in group FM and 93 ± 5% in Group-NC. The FiO₂-EtO₂ difference was 4% in both groups. During the 90 s apnoea following pre-oxygenation, there was a fall in the PaO₂ by 38% in Group-FM and 12% in Group-NC (P = 0.000). Increase in PaCO₂ was similar in both groups (Group-FM: 44 [range: 32-55] mmHg; Group-NC: 42 [range: 33-54] mmHg, P = 0.809).

Conclusion: Apnoeic insufflation of O₂ using a nasopharyngeal catheter along with facemask oxygenation is more effective in sustaining PaO₂ for 90 s during RSI than facemask-only oxygenation in patients undergoing emergency laparotomy.