Abstracts of the ICARE 2023 77th SIAARTI National Congress

Rapid sequence induction (RSI) is an anesthesia technique for tracheal intubation in patients at high risk of aspiration of gastric content. As manual ventilation is not recommended in RSI, pre-oxygenation is a fundamental strategy to ensure an adequate period of safe apnea [1]. The current standard for pre-oxygenation entails spontaneous facemask ventilation (FM) delivering a fraction of inspired oxygen (FiO2) of 100% at 15 L/min flow such as to reach an end tidal O2 (EtO2) of at least 90% prior to the administration of induction medications and myorelaxants. The use of High Flow Nasal Oxygen (HFNO) may offer some advantages over the standard technique [2]. Patients and methods After obtaining informed consent, patients undergoing anesthesia with indication for RSI were randomized for FM or HFNO. Patients belonging to the FM-group were pre-oxygenated with an anesthesia mask for 5 minutes (15 L/min, FiO2 of 1). After the anesthesia induction, the mask was left in place during the apnea time and removed during the intubation. Patients of the HFNO-group were pre-oxygenated for 5 minutes with HFNO at 40 L/min and FiO2 1. Oxygen flow was increased to 70 l/min after the anesthesia induction and the cannula was left in place during the apnea time and the intubation (figure 1). PaO2, PaCO2, SpO2 and oxygen reserve index (ORi) were measured before, at 5 minutes of pre-oxygenation and immediately after intubation. Apnea time was measured in each patient. The variables considered were compared. For each patient, the variation of PaO2 and PaCO2 during apnea was related to the apnea time to obtain and compare the mean variation per second during apnea of these variables. Results We enrolled 50 patients and randomized 25 for each group. There was no difference in the baseline patient characteristics and basal SpO2, PaO2 and PaCO2. Patients in the HFNO group showed a lower decrease in PaO2 during the apnea time (p=0.0009). In a sub-population with apnea time greater than 300 seconds, PaO2 at intubation was significantly higher in the HFNO group (p=0.046) than in FMgroup. Differently, there were no differences between the two groups in PaCO2 (table 1-2). Conclusions HFNO might increase the safe apnea compared to the standard method for the pre-oxygenation of patients undergoing RSI offering additional safety especially when the intubation procedure needs more time. In addition, ORi can be a useful non-invasive monitoring of the patient oxygen status during RSI. There was no evidence in CO2 clearance under HFNO.