Discussion
neuromuscular blockade, atelectasis, neuromuscular block, ORI, muscle paralysis
ATELECTASIS, NEUROMUSCULAR BLOCKADE
The present study revealed that the ORI was not significantly different between patients who received HFNO and facemask oxygenation. The ORI reflects a wider range of PaOThere was no significant difference in the maximum ORI obtained by the different preoxygenation methods used or in the time required to reach the maximum ORI. Pillai et al. reported that HFNO at 60 L·minHerein, 23% of patients who underwent HFNO reported discomfort at a flow rate of 40 L·minEndotracheal intubation was conducted 3 min after the neuromuscular block was administered, during which time the ORI decreased. The ORI was not significantly different between the two groups during this period. While mask ventilation was possible after neuromuscular blockade in the facemask oxygenation group, the ORI continued to decrease, possibly due to the ventilation/perfusion mismatch caused by atelectasis after anaesthesia induction and the decreased functional residual capacity due to muscle paralysis [Although oxygen was supplied at a constant flow through the nasal cannula without ventilation, patients in the HFNO group had a similar oxygenation status during mechanical positive pressure ventilation as the facemask oxygenation group. These findings are consistent with previous results—HFNO did not cause significant differences in patient lung volume relative to positive-pressure ventilation, as measured via electrical impedance tomography [Other advantages of HFNO include facilitation of a high level of humidification in the airway and reduction of atelectasis, which is positive end-expiratory pressure effect with the mouth closed [This study had some limitations. First, the ORI may differ at different flow rates of HFNO. A flow rate of 40 L·min