High-Flow Nasal Oxygen Improves Safe Apnea Time in Morbidly Obese Patients Undergoing General Anesthesia: A Randomized Controlled Trial

Abstract

BACKGROUND: Morbidly obese patients undergoing general anesthesia are at risk of hypoxemia during anesthesia induction. High-flow nasal oxygenation use during anesthesia induction prolongs safe apnea time in nonobese surgical patients. The primary objective of our study was to compare safe apnea time, between patients given high-flow nasal oxygenation or conventional facemask oxygenation during anesthesia induction, in morbidly obese surgical patients. METHODS: Research ethics board approval was obtained. Elective surgical patients ≥18 years with body mass index ≥40 kg·m−2 were included. Patients with severe comorbidity, gastric reflux disease, known difficult airway, or nasal obstruction were excluded. After obtaining informed consent patients were randomized. In the intervention (high-flow nasal oxygenation) group, preoxygenation was provided by 100% nasal oxygen for 3 minutes at 40 L·minute−1; in the control group, preoxygenation was delivered using a facemask with 100% oxygen, targeting end-tidal O2 >85%. Anesthesia was induced with propofol, remifentanil, and rocuronium. Bag-mask ventilation was not performed. At 2 minutes after rocuronium, videolaryngoscopy was performed. If the laryngoscopy grade was I or II, laryngoscope was left in place and the study was continued; if grade III or IV was observed, the patient was excluded from the study. During the apnea period, high-flow nasal oxygenation patients received nasal oxygen at 60 L·minute−1; control group patients received no supplemental oxygen. The primary outcome, safe apnea time, was reached when oxygen saturation measured by pulse oximetry (Spo 2) fell to 95% or maximum 6 minutes of apnea. The patient was then intubated. T tests and χ2 analyses were used to compare groups. P < .05 was considered significant. RESULTS: Forty patients completed the study. Baseline parameters were comparable between groups. Safe apnea time was significantly longer (261.4 ± 77.7 vs 185.5 ± 52.9 seconds; mean difference [95% CI], 75.9 [33.3–118.5]; P = .001) and the minimum peri-intubation Spo 2 was higher (91.0 ± 3.5 vs 88.0 ± 4.8; mean difference [95% CI], 3.1 [0.4–5.7]; P = .026) in the high-flow nasal oxygenation group compared to the control group. CONCLUSIONS: High-flow nasal oxygenation, compared to conventional oxygenation, provided a longer safe apnea time by 76 seconds (40%) and higher minimum Spo 2 in morbidly obese patients during anesthesia induction. High-flow oxygenation use should be considered in morbidly obese surgical patients.

Carbon dioxide clearance during apnoea with high‐flow nasal oxygen: epiphenomenon or a failure to THRIVE?

“…In contrast to the other clinically available apnoeic oxygenation devices (low flow nasal prongs , insufflating laryngoscopes , buccal oxygen ) it is remarkable that high‐flow nasal oxygen during apnoea in adults became established into practice on the basis of several case series alone. The first randomised controlled trial in adults with a prescribed apnoeic test has only just been published . This confirmed an oxygenation benefit in morbidly obese patients, extending the safe apnoea time from 180 to 261 s, but reported no difference in plateau end‐tidal carbon dioxide at the end of apnoea (5.11 kPa vs. 4.99 kPa).…”

“…High‐flow nasal oxygen administration during apnoea was first described in a case series of 25 adults in Anaesthesia in 2015 . Subsequently, case series by other groups , randomised trials and widespread international experience have confirmed beyond doubt that this is a highly effective approach to apnoeic oxygenation. However, the data surrounding the concept of carbon dioxide clearance during apnoea with high‐flow nasal oxygen is more limited, raising the possibility that recent modelling and simulation exercises are premature, and that appropriately conducted randomised trials in adults are still required.…”

“…High-flow nasal oxygen administration during apnoea was first described in a case series of 25 adults in Anaesthesia in 2015 [1]. Subsequently, case series by other groups [2,3], randomised trials [4][5][6] and widespread international experience have confirmed beyond doubt that this is a highly effective approach to apnoeic oxygenation.…”

Measurement of airway pressure during high‐flow nasal therapy in apnoeic oxygenation: a randomised controlled crossover trial*

“…Since Patel et al reported that HFNT can prolong the safe apnoea period during airway surgery [10], HFNT has been used for pre-oxygenation [26,27]; for awake fibreoptic intubation in adults [28] and morbidly obese patients [29];…”

THRIVE: five years on and into the COVID-19 era

“…The THRIVE effect of extended safe apnoea time prior to desaturation with reduced rate of carbon dioxide accumulation compared with historical studies of 'classical' apnoeic oxygenation using low-flow oxygen, has now been reproduced in: (i) many centres worldwide; [5][6][7][8][9][10] (ii) in different patient populations; 5 (iii) in patients with 'difficult' and compromised/stridulous airways; 2,10 (iv) during both peri-intubation 6 and extended apnoea application of THRIVE; [7][8][9] and (v) using different methods to measure carbon dioxide, e.g. end-tidal CO 2 (ETCO 2 ) on termination of THRIVE, transcutaneous CO 2 , and PaCO 2 .…”