[abstract] END-TIDAL COMPARED TO ARTERIAL CARBON DIOXIDE TENSION DURING HYPERBARIC OXYGEN THERAPY

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[abstract] END-TIDAL COMPARED TO ARTERIAL CARBON DIOXIDE TENSION DURING HYPERBARIC OXYGEN THERAPY

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Title: [abstract] END-TIDAL COMPARED TO ARTERIAL CARBON DIOXIDE TENSION DURING HYPERBARIC OXYGEN THERAPY
Author: Haberstock, D; Weaver, LK; Churchill, S
Abstract: BACKGROUND: During mechanical ventilation of patients treated with HBO2 therapy, it may be important to monitor arterial carbon dioxide tension (PaCO2). End-tidal CO2 (EtCO2) is used in the ICU as a surrogate for the PaCO2, and we routinely use EtCO2 measurements to monitor the adequacy of mechanical ventilation of patients treated with HBO2 therapy, yet we do not know how EtCO2 correlates with the PaCO2. MATERIALS AND METHODS: Retrospective chart review (2004) of intubated, mechanically ventilated patients treated with HBO2 who had both EtCO2 and PaCO2 measurements. We used a Capnogard EtCO2 monitor (Novametrix, Wallingford, CT). The airway gases were side-stream sampled from the patient's endotracheal tubes and passed out of the monoplace chamber to the EtCO2 monitor. We used a Radiometer 520 (Copenhagen, Denmark) for PaCO2 measurements. Arterial blood was withdrawn and analyzed in methods described previously.1 Because EtCO2 gases were sampled inside the chamber, but measured at atmospheric pressure we used a corrected EtCO2 = measured EtCO2 x chamber pressure/atmospheric pressure in atm abs. Data are expressed as mean +/-SD. RESULTS: We analyzed EtCO2 and PaCO2 from 15 patients (9 necrotizing infections, 2 crush, 2 AGE, 1 failing flap). At baseline: PaO2/FiO2 = 243 +/- 106; minute ventilation = 9.4 +/- 2.4 L/m; PaCO2 = 39.6 +/- 6.4 Torr, and the EtCO2 = 29.9 +/-7.3 Torr. During HBO2, the PaCO2 - EtCO2 ranged from 36 to +27 Torr. Only 16 of 35 measurement pairs were within +/- 10 Torr. There was poor correlation between EtCO2 and PaCO2 (EtCO2 = 0.4778 x PaCO2 + 23; R2 = 0.04). CONCLUSIONS: With the Capnogard monitor, the EtCO2 can be used to follow trends, but did not correlate with the PaCO2, including at atmospheric pressure. 1Weaver LK, Howe S. Normobaric Measurement of Arterial Oxygen Tension in Subjects Exposed to Hyperbaric Oxygen. Chest 1992;102:1175-81.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/1761
Date: 2005

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  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

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