Apnoeic oxygenation with high-flow nasal oxygen for laryngeal surgery: a case series

Surgery under apnoeic conditions with the use of high-flow nasal oxygen is novel. Between November 2016 and May 2017, 28 patients underwent tubeless laryngeal or tracheal surgery under apnoeic conditions with high-flow nasal oxygen as the sole method of gas exchange. Patients received total intravenous anaesthesia and neuromuscular blocking agents for the duration of their surgery. The median (IQR [range]) apnoea time was 19 (15-24 [9-37]) min. Four patients experienced an episode of oxygen desaturation to a value between 85% and 90%, lasting less than 2 min in each case. Median (IQR [range]) end-tidal carbon dioxide (ETCO2) level following apnoea was 8.2 (7.2-9.4 [5.8-11.8]) kPa. The mean (SD) rate of ETCO2 increase was 0.17 (0.07) kPa. min(-1) from an approximated baseline value of 5.00 kPa. Venous blood sampling from 19 patients demonstrated a mean (SD) partial pressure of carbon dioxide (PVCO2) of 6.29 (0.71) kPa at baseline and 9.44 (1.12) kPa after 15 min of apnoea. This equates to a mean (SD) PVCO2 rise of 0.21 (0.08) kPa. min(-1) during this period. Mean (SD) pH was 7.40 (0.03) at baseline and 7.23 (0.04) after 15 min of apnoea. Mean (SD) standard bicarbonate was 26.7 (1.8) mmol.l(-1) at baseline and 25.4 (1.8) mmol.l(-1) at 15 min. We conclude that high-flow nasal oxygen under apnoeic conditions can provide satisfactory gas exchange in order to allow tubeless anaesthesia for laryngeal surgery.