Effect of a heated humidifier during continuous positive airway pressure delivered by a helmetReport as inadecuate




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Critical Care

, 12:R55

First Online: 21 April 2008Received: 22 November 2007Revised: 13 March 2008Accepted: 21 April 2008

Abstract

IntroductionThe helmet may be an effective interface for the delivery of noninvasive positive pressure ventilation. The high internal gas volume of the helmet can act as a -mixing chamber-, in which the humidity of the patient-s expired alveolar gases increases the humidity of the dry medical gases, thus avoiding the need for active humidification. We evaluated the temperature and humidity of respiratory gases inside the helmet, with and without a heated humidifier, during continuous positive airway pressure CPAP delivered with a helmet.

MethodsNine patients with acute respiratory failure arterial oxygen tension-fractional inspired oxygen ratio 209 ± 52 mmHg and 10 healthy individuals were subjected to CPAP. The CPAP was delivered either through a mechanical ventilator or by continuous low 40 l-min or high flow 80 l-min. Humidity was measured inside the helmet using a capacitive hygrometer. The level of patient comfort was evaluated using a continuous scale.

ResultsIn patients with acute respiratory failure, the heated humidifier significantly increased the absolute humidity from 18.4 ± 5.5 mgH2O-l to 34.1 ± 2.8 mgH2O-l during ventilator CPAP, from 11.4 ± 4.8 mgH2O-l to 33.9 ± 1.9 mgH2O-l during continuous low-flow CPAP, and from 6.4 ± 1.8 mgH2O-l to 24.2 ± 5.4 mgH2O-l during continuous high-flow CPAP. Without the heated humidifier, the absolute humidity was significantly higher with ventilator CPAP than with continuous low-flow and high-flow CPAP. The level of comfort was similar for all the three modes of ventilation and with or without the heated humidifier. The findings in healthy individuals were similar to those in the patients with acute respiratory failure.

ConclusionThe fresh gas flowing through the helmet with continuous flow CPAP systems limited the possibility to increase the humidity. We suggest that a heated humidifier should be employed with continuous flow CPAP systems.

AbbreviationsCPAPcontinuous positive airway pressure

NPPVnoninvasive positive pressure ventilation.

Electronic supplementary materialThe online version of this article doi:10.1186-cc6875 contains supplementary material, which is available to authorized users.

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Author: Davide Chiumello - Monica Chierichetti - Federica Tallarini - Paola Cozzi - Massimo Cressoni - Federico Polli - Riccardo Co

Source: https://link.springer.com/







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