Water content of delivered gases during Helmet Continuous Positive Airway Pressure in healthy subjects: Humidification during Helmet CPAP

Alberto Lucchini; Stefano Bambi; Stefano  Elli; Martina Bruno; Roberto Dallari; Pamela Puccio; Silvia Villa; Roberto Rona; Roberto Fumagalli; Giacomo Bellani; Giuseppe Foti

doi:10.23750/abm.v90i11-S.8820

Water content of delivered gases during Helmet Continuous Positive Airway Pressure in healthy subjects

Humidification during Helmet CPAP

Authors

Alberto Lucchini ASST Monza, Ospedale San Gerardo - università degli Studi di Milano-Bicocca
Stefano Bambi Medical and Surgical Intensive Care Unit - Careggi University Hospital, Florence, Italy
Stefano Elli General Intensive Care Unit, Emergency Department – ASST Monza - San Gerardo Hospital, Via Pergolesi 33, Monza (MB), Italy - University of Milano-Bicocca.
Martina Bruno General Intensive care Unit - Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, MI, Italy
Roberto Dallari Anesthesia Service – Carate Hospital, ASST Vimercate, MB - Italy
Pamela Puccio General Intensive care unit – Prato Hospital, USL Centro Toscana, Italy
Silvia Villa General Intensive Care Unit, Emergency Department - ASST Monza - San Gerardo Hospital, University of Milano-Bicocca, Monza, Italy
Roberto Rona General Intensive Care Unit, Emergency Department – ASST Monza - San Gerardo Hospital, Via Pergolesi 33, Monza (MB), Italy - University of Milano-Bicocca
Roberto Fumagalli Department of Anesthesia and Intensive Care Medicine, Niguarda Ca' Granda, University Hospital of Milano-Bicocca, Milano, Italy.
Giacomo Bellani General Intensive Care Unit, Emergency Department – ASST Monza - San Gerardo Hospital, Via Pergolesi 33, Monza (MB), Italy - University of Milano-Bicocca
Giuseppe Foti General Intensive Care Unit, Emergency Department – ASST Monza - San Gerardo Hospital, Via Pergolesi 33, Monza (MB), Italy - University of Milano-Bicocca

DOI: https://doi.org/10.23750/abm.v90i11-S.8820

Keywords:

CPAP, Humidification, Comfort, NIV, Helmet, heated humidifier

Abstract

Introduction: During Continuous Positive Pressure Ventilation delivered through helmet, the patient inhales high flows of gas without adequate conditioning. However, the need to humidify the inspired gas during Helmet-CPAP, has not been sufficiently explored. Methods: Experimental design study. Six healthy individuals underwent High Flow Helmet CPAP with different gas flows (60 and 80 L/min) and FiO₂ (0.35, 0.5, 0.7 and 1) generated by a Venturi system, with and without active humidification. The active humidifier setting was 26 ° at the humidification chamber and 28 ° at the helmet gas inlet. At each setting, measurements about temperature and relative humidity inside helmet were taken. Comfort level at each setting was evaluated using a visual analog scale rated from 0 to 10. Results: Without heated humidification, the mean value of absolute humidity in the eight combinations investigated was 5.9±2.1 mg H₂O/L, with a mean temperature of 25.8±0.9°. With heated humidification mean absolute humidity was 15.0±3.5 mg H₂O/L with mean temperature of 29.0±0.1°. The median comfort scale value was 6 (IQR: 5.25-6.75) during the phase without humidification vs 8 (7.25-8.0 - P<0.01) when active humidification was applied. Conclusions: In healthy subjects undergoing High Flow Helmet CPAP, heated humidifiers with heated wires tubes are necessary to avoid the under-humidification inside the helmet. To obtain patient’s comfort and airways mucosal humidification during continuous Helmet CPAP, the most desirable conditions are reached by heated humidifiers with a humidifying chamber temperature settled between 26-28°C.