Air Trapping as a Serious Problem during Mechanical Ventilation—A Case Report

Abstract

A middle-aged man with a five-year history of respiratory distress was hospitalized in acute respiratory failure (ARF). He was intubated, started on mechanical ventilation (MV) at tidal volumes of 700 ml, and immediately became agitated and soon stopped breathing. MV was stopped and the patient resumed spontaneous but inadequate breathing. No mechanical obstruction to ventilation was discovered and MV was started again. The patient again became uncomfortable, prolonged expiration was noted, chest diameter increased, and spontaneous breathing ceased again. After resumption of spontaneous breathing, MV was started with tidal volume reduced from 700 to 400 ml and the difficulty did not recur. A subsequent clinical trial at high tidal volumes to document gas trapping showed that as much as 150 ml gas was trapped per breath. Weaning from MV was successful but the patient later died from another episode of ARF. Postmortem examination showed severe emphysema, right-heart hypertrophy, and numerous bilateral emphysematous bullae. Air trapping may have occurred in bullous areas, because of increased collapsibility of airways, because of asthma, or from a combination of factors. The emergency problem of gas trapping during MV was solved by reduction of tidal volume to reduce expiratory time and permit recovery of functional residual capacity between expiration and inspiration.