Respiratory rate and PaCO2 of spontaneously breathing adults are not affected by removing a heat moisture exchanging filter (HMEF) from the breathing circuit

Bryan DeHaven, O. C. Kirton, J. Morgan, David V Shatz, M. Navarro

Research output: Contribution to journalArticle

Abstract

Introduction: A recurrent clinical perception is postulated on a heat moisture exchange filter (HMEF) somehow "stressing" patients, possibly causing them to becoming hypercarbic and tachypneic. We studied the response of spontaneously breathing adults augmented with pressure support ventilation (PSV), SIMV and CPAP, to the removal of the passive HMEF from the ventilator Circuit, and changing it to an active, hot water heated wire humidification circuit (hw-w). Methods: We prospectively, sequentially studied 50 adult patients in a 25 bed trauma ICU of an academic medical center over 5 months who received augmented ventilation with PSV, SIMV and CPAP. Respiratory rate, PaCO2, pH, and temperature were measured before and after the patient ventilator circuit humidification was changed from a HMEF (Pall BB-100F) to a Hw-w ventilator circuit, at the same level of ventilatory support. Only these clinical variables were assessed, as they were frequently the only data utilized by the clinician when evaluating the patient. Results: There were no differences in respiratory rate, pH, temperature or PaCO2 between the two different ventilator circuits. Data were evaluated by student's t-test. Conclusion: The data demonstrate that patients with intact respiratory drives and existing spontaneous respiration ventilated with PSV and CPAP are unlikely to be adversely effected by the addition of added mechanical dead space. Their respiratory rate and PaCO2 do not change when passive humidification de-vices are removed and replaced with an active humidification system. HMEF Water Humidifier p-value PaCO2 mmHg 46+8 47+10 0.47 pH 7.39+0.09 7.38+0.09 0.49 Reipiatory rate 25+7 26+7 0.23 Tempeature F 100.1+1.6 100.1+1.6 0.89.

Original languageEnglish (US)
JournalCritical Care Medicine
Volume27
Issue number12 SUPPL.
StatePublished - 1999
Externally publishedYes

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine

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