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Updated: Aug 6, 2026

Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
Published on: January 29, 2011
Bimodality of expiratory time in patients anaesthetized with propofol
1University Department of Anaesthesia, Southmead Hospital, Bristol.
Abstract:
In the records of breathing from five of 32 patients in two previous studies, the distribution of expiratory times appeared bimodal. Records of breathing from another 40 patients anaesthetized for up to 1 h with propofol infusions were examined; there was clear evidence of bimodality in the distribution of expiratory time in 14 records. The bimodality was independent of tidal volume or inspiratory time, and seemed to be caused largely by differing durations of expiratory pause. In six records there was a change of state between unimodality and bimodality. There was no obvious common factor to explain the bimodality or why a change of state should occur.
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