Anesthesia and Intraoperative High-Frequency Oscillatory Ventilation During Burn Surgery

Abstract

High-frequency oscillatory ventilation (HFOV) is a mainstay in the ventilatory management of severe acute respiratory distress syndrome in our burn center. Many patients require burn surgery while on HFOV, potentially necessitating the use of HFOV during general anesthesia in the operating room. The purpose of this study was to describe the technique of providing and maintaining intraoperative HFOV. This is a retrospective analysis of the hospital and anesthesia records of all adult burn patients who went to the operating room on HFOV at our regional burn center between October 22, 1999, and April 30, 2009. There were 57 procedures performed on 36 patients who were receiving HFOV for severe acute respiratory distress syndrome available for analysis (age 45 ± 16 years, %TBSA burn 43 ± 14, % full-thickness burn 32 ± 19, and 69% with inhalation injury). Intraoperative HFOV settings were mean airway pressure 33 ± 4 cm H₂O, frequency 5 ± 1 Hz, and FiO₂ 0.7 ± 0.2. There were no significant changes in oxygenation as measured by the PaO₂/FiO₂ ratio and the oxygenation index, but there was a transient but significant increase in PaCO₂ intraoperatively. Existing continuous infusions of midazolam, opioids, and neuromuscular blockers were continued during surgery and were augmented by a variety of parenteral agents, including propofol, fentanyl, and ketamine during surgery. Prone positioning was required in 16 of 57 procedures. Subanalysis of the prone cases showed no significant changes in the PaO₂/FiO₂ ratio or oxygenation index but again showed a significant but temporary increase in intraoperative PaCO₂. HFOV was aborted for conventional mechanical ventilation in three cases due to respiratory deterioration (2 cases) and hemodynamic instability (1 case). There were no intraoperative deaths. In-hospital mortality was 33%. Intraoperative HFOV was feasible and safe in the overwhelming majority of cases, and aside from an inconsequential period of intraoperative hypercapnia, this was not associated with any hemodynamic instability or compromise in oxygenation.