Spontaneous Ventilation Using Target-Controlled Propofol Infusion for Microlaryngoscopy in Adults: A Retrospective Audit

Abstract

We conducted a retrospective audit of 285 adult elective microlaryngoscopy cases in our institution over a three-and-a-half year period. Conventional anaesthesia with intubation and mechanical ventilation was the most common technique, used in 71% of cases. Tubeless spontaneous ventilation during total intravenous anaesthesia with a target-controlled infusion of propofol (SVTCI) was the most common alternative. Spontaneous ventilation with target-controlled infusion was used for 79 (27.7%) anaesthetic inductions and was continued through the maintenance phase for 60 patients (21.1%). Jet and intermittent ventilation were both used infrequently (1% each). The most common SVTCI technique since 2013 involved adjusting the target-controlled infusion rate during induction using a formula we developed based on intermittently increasing the target rate, such that the predicted plasma concentration minus the predicted effect site concentration was maintained at 1 μg/ml. We found that this method maintained ventilation during induction more reliably than other SVTCI strategies, and was associated with fewer complications than other spontaneous ventilation techniques or mechanical ventilation: it was associated with only one (3.1%) failed induction and one (3.9%) episode of apnoea. Jet ventilation was associated with the most severe complications, including two cases of barotrauma.

SponTaneous Respiration using IntraVEnous anaesthesia and Hi-flow nasal oxygen (STRIVE Hi) maintains oxygenation and airway patency during management of the obstructed airway: an observational study

“…This finding contrasts our previous STRIVE series without the use of HFNO 9 , and it is likely that the preserved oxygenation using HFNO also resulted from an increased functional residual capacity.…”

“…Although minor jaw thrust was applied to ensure airway patency, no patient required major upper airway intervention or adjuvant use. This was also in contrast to our initial STRIVE series without HFNO, where upper airway interventions were common and nasopharyngeal airways were required in most of the inductions 9 . Similar upper airway benefits using HFNO, attributed to the nasopharyngeal pressure generated by high flow rates, have been reported in sedated patients undergoing bronchoscopy and patients with OSA 5 7 8 …”

“…anaesthesia to maintain spontaneous ventilation has several advantages compared with the more traditional inhalation induction 22 23 , which was associated with multiple failures in the 4 th National Audit Project (NAP4) 18 . It has good airway reflex suppression; separates anaesthesia delivery from ventilation and its use can extend beyond the induction to facilitate tubeless airway surgery 9 22 . In addition, as HFNO is an open oxygen delivery system, it cannot be used during an inhalation induction, as a result of the dilutional effect on the inspired volatile agents 24 …”

“…anaesthesia is the primary technique used at our institution for tubeless airway surgery 9 . Although we have found spontaneous ventilation to be associated with numerous benefits, general anaesthesia does have detrimental effects on respiratory mechanics, which may limit application of the technique in certain patient subgroups, particularly those with severe respiratory co-morbidity.…”

Tubeless Total Intravenous Anesthesia Spontaneous Ventilation for Adult Suspension Microlaryngoscopy

“…Although both of these agents can cause apnea, with proper titration, the delicate balance of anesthesia for SML with spontaneous ventilation can be achieved in most patients. 3,[7][8][9] Other adjunctive anesthetic agents were used in this series. Ketamine was used in 9 cases successfully.…”