Effect of humidifying devices on the measurement of tidal volume by mechanical ventilators

Abstract

Monitored expiratory tidal volume was underestimated by approximately 10%, when using a heat-moisture exchanger.

Humidification During Noninvasive Ventilation in the Critically IllThe Authors Respond:

“…3,4 In some cases, suboptimal pressure support levels may be insufficient to overcome the humidifier's internal resistance and, hence, may lead indirectly to a slower decrease in PaCO 2 , as shown in the current study. 2 Such effect will be of greater relevance in patients with higher degrees of expiratory air flow obstruction and acidosis.…”

“…Fujita et al showed that monitored expiratory tidal volume was underestimated with different ventilators from 8% to 14% when using an HME. 4 Thus, the difference we found in minute ventilation (15.5 Ϯ 6.4 L/min with HME vs 13.7 Ϯ 5.8 L/min with HH, P Ͻ .001) may have been even larger if one considers a potential overestimation of volumes with HH.…”

“…High V E, particularly in patients with hypercapnia and acidosis, could have a significant effect on the internal resistance of HMEs. [3][4][5] …”

Influence of breathing resistance of heat and moisture exchangers on tracheal climate and breathing pattern in laryngectomized individuals

“…Theoretically, warm and humid air has a larger volume expansion that requires an additional correction. 17 …”

Malfunction of heat and moisture exchanger filters: Causality or unresolved problem?

“…This is crucial point during prolonged mechanical ventilation[5] and monitoring ventilatory parameters. [6]…”