OBJECTIVE: To assess the behavior of different helmets after discontinuation of fresh gas flow by disconnection at the helmet inlet, flow generator, or gas source. DESIGN AND SETTING: Randomized physiological study in a university research laboratory. PATIENTS: Five healthy volunteers. INTERVENTION: CPAP (FIO2 50%, PEEP 5 cmH2O) delivered in random sequence with three different helmets: 4Vent (Rüsch), PN500 (Harol), CaStar (StarMed) with antisuffocation valve open or locked. For each helmet all three disconnections were randomly employed up to 4 min. MEASUREMENTS AND RESULTS: During flow disconnection we measured: respiratory rate and tidal volume by respitrace; inspiratory and expiratory CO2 concentration, and FIO2 from a nostril; SpO2 by pulse oxymetry. Independently of the site of disconnection we observed a fast increase in CO2 rebreathing and minute ventilation, associated with a decrease in inspired O2 concentration. In the absence of an operational safety valve, larger helmet size and lower resistance of the inlet hose resulted in slower increase in CO2 rebreathing. The presence of the safety valve limited the rebreathing of CO2, and the increase in minute ventilation but did not protect from a decrease in FIO2 and loss of PEEP. CONCLUSIONS: While the use of a safety valve proved effective in limiting CO2 rebreathing, it did not protect from the risk of hypoxia related to decrease in FIO2 and loss of PEEP. In addition to a safety antisuffocation valve, a dedicated monitoring and alarming systems are needed to employ helmet CPAP safely.
RCT Entities:
OBJECTIVE: To assess the behavior of different helmets after discontinuation of fresh gas flow by disconnection at the helmet inlet, flow generator, or gas source. DESIGN AND SETTING: Randomized physiological study in a university research laboratory. PATIENTS: Five healthy volunteers. INTERVENTION: CPAP (FIO2 50%, PEEP 5 cmH2O) delivered in random sequence with three different helmets: 4Vent (Rüsch), PN500 (Harol), CaStar (StarMed) with antisuffocation valve open or locked. For each helmet all three disconnections were randomly employed up to 4 min. MEASUREMENTS AND RESULTS: During flow disconnection we measured: respiratory rate and tidal volume by respitrace; inspiratory and expiratory CO2 concentration, and FIO2 from a nostril; SpO2 by pulse oxymetry. Independently of the site of disconnection we observed a fast increase in CO2 rebreathing and minute ventilation, associated with a decrease in inspired O2 concentration. In the absence of an operational safety valve, larger helmet size and lower resistance of the inlet hose resulted in slower increase in CO2 rebreathing. The presence of the safety valve limited the rebreathing of CO2, and the increase in minute ventilation but did not protect from a decrease in FIO2 and loss of PEEP. CONCLUSIONS: While the use of a safety valve proved effective in limiting CO2 rebreathing, it did not protect from the risk of hypoxia related to decrease in FIO2 and loss of PEEP. In addition to a safety antisuffocation valve, a dedicated monitoring and alarming systems are needed to employ helmet CPAP safely.
Authors: Jean-Marie Tonnelier; Gwenaël Prat; Emmanuel Nowak; David Goetghebeur; Anne Renault; Jean Michel Boles; Erwan L'her Journal: Intensive Care Med Date: 2003-11 Impact factor: 17.440
Authors: Nicolò Patroniti; Giuseppe Foti; Annamaria Manfio; Anna Coppo; Giacomo Bellani; Antonio Pesenti Journal: Intensive Care Med Date: 2003-08-28 Impact factor: 17.440
Authors: Massimo Antonelli; Elie Azoulay; Marc Bonten; Jean Chastre; Giuseppe Citerio; Giorgio Conti; Daniel De Backer; François Lemaire; Herwig Gerlach; Johan Groeneveld; Goran Hedenstierna; Duncan Macrae; Jordi Mancebo; Salvatore M Maggiore; Alexandre Mebazaa; Philipp Metnitz; Jerme Pugin; Jan Wernerman; Haibo Zhang Journal: Intensive Care Med Date: 2008-01-31 Impact factor: 17.440
Authors: Manuela Milan; Alberto Zanella; Stefano Isgrò; Salua Abd El Aziz El Sayed Deab; Federico Magni; Antonio Pesenti; Nicolò Patroniti Journal: Intensive Care Med Date: 2011-03-30 Impact factor: 17.440