Intraoperative Awareness with Recall Due to Inadvertent Use of Activated Charcoal Filters

Barry Swerdlow

doi:10.4236/ojanes.2019.96012

Abstract

A 57-year-old woman underwent abdominal surgery with a subarachnoid block supplemented by “light” general endotracheal anesthesia consisting of a propofol infusion and a sub-MAC concentration of sevoflurane. The previous case in the same operating room had involved a malignant hyperthermia-susceptible patient, and charcoal filters had been placed in the breathing circuit as a precautionary measure. Because it had not been used on the evening beforehand, the circuit with filters was left in situ with a strip of tape indicating that it was clean. The woman’s anesthesiologist assumed that these filters were heat and moisture exchanger filters in an unused circuit and therefore did not remove them. Subsequently, the patient had awareness with intraoperative recall. This case highlights the potential for inadvertent use of activated charcoal filters with potentially catastrophic results. Such unintended utilization of these products likely can be minimized by improved labeling techniques.

Highlights

Awareness with recall (AWR), including both intraoperative consciousness and explicit recall of intraoperative events during general anesthesia, is a potentially devastating occurrence
An increasingly common, opioid-sparing anesthetic technique for elective major abdominal surgery utilizes a combination of neuraxial blockade and a minimal level of general anesthesia—the latter addition largely to allow for controlled ventilation with adequate surgical relaxation
Because of its many beneficial properties, as part of this scheme, propofol is frequently delivered by infusion often in combination with a sub-MAC dose of volatile agent to minimize the risk of AWR

Summary

Introduction

Awareness with recall (AWR), including both intraoperative consciousness and explicit recall of intraoperative events during general anesthesia, is a potentially devastating occurrence. When “light” general anesthesia is predicated largely on a propofol infusion, supplementation with measured doses of potent intravenous (IV) amnestics or with a sub-MAC concentration of inhalational anesthesia has been advocated [2] In this context, an increasingly common, opioid-sparing anesthetic technique for elective major abdominal surgery utilizes a combination of neuraxial blockade and a minimal level of general anesthesia—the latter addition largely to allow for controlled ventilation with adequate surgical relaxation. Because of its many beneficial properties, as part of this scheme, propofol is frequently delivered by infusion often in combination with a sub-MAC dose of volatile agent to minimize the risk of AWR In such cases, failure to deliver inhalational anesthesia may result in AWR, if relatively low doses of propofol are employed. The current report details the occurrence of AWR in a patient otherwise not at high risk for this phenomenon, and highlights an unusual equipment-related etiology for such an adverse event

Case Description

Discussion

Conclusion