LAUSR

THRIVE is safe during apnoeic oxygenation [2]. It is therefore expected that apnoeic oxygenation using THRIVE is superior to no oxygenation during intubation, regardless of the type of pre-oxygenation. There is evidence that apnoeic oxygenation using nasal oxygen flow rates of 2– 15 l.min 1 prolongs safe apnoea time [3, 4]. It would have been interesting to choose an active comparator (e.g. nasal cannula oxygen at 2– 10 l.min ) instead of no oxygen administration during apnoea to see if THRIVE provides a significant benefit over lower oxygen flow rates, considering the low cost of standard nasal cannula compared with the relatively expensive THRIVE equipment. We note that SpO2 dropped to 71% within 150 s in one patient in the facemask group, but no details on the specific circumstances under which this profound desaturation occurred were provided, and whether not analysing this patient would have changed the results significantly. Once apnoea occurred, anaesthetists waited for a median of 58 s in the facemask group before inserting the laryngoscope (apnoea time – intubation time = time until laryngoscope insertion). In the THRIVE group they started after 68 s. Is there any reason why it took longer in the THRIVE group to insert the laryngoscope during these ‘rapid’ sequence intubations? Although THRIVE might reduce the desaturation risk, the risk of regurgitation and aspiration are still there. The start of apnoea time was assessed differently for the two groups. This needs to be explained to avoid bias. Monitoring of endtidal CO2 was used in the facemask group to determine if spontaneous breathing was present and the disappearance of end-tidal CO2 was defined as the start of apnoea. In contrast, in the THRIVE group, visual observation of chest movements was used to confirm cessation of spontaneous ventilation. Small respiratory movements are sometimes difficult to observe by eye but easier to detect using ETCO2 traces on the monitor. Could the different methods of assessing the start of apnoea have contributed to the duration of apnoea? Another study has described the potential benefits of THRIVE during RSI [5], but the benefits of THRIVE over low-flow nasal cannula oxygen (as well as any added ventilatory effects) still remain unclear. Finally, we suggest that the authors studied rapid sequence intubation rather than rapid sequence induction, as intubation time was measured rather than induction time. We are aware that in everyday use, the ‘I’ in ‘RSI’ is used interchangeably to mean ‘induction’ or ‘intubation’, but perhaps research needs to standardise the ‘I’ to denote ‘induction’, as originally intended?