OBJECTIVE: We examined whether additional helmet flow obtained by a single-circuit and a modified plateau valve applied at the helmet expiratory port (open-circuit ventilators) improves CO(2) wash-out by increasing helmet airflow. DESIGN AND SETTING: Randomized physiological study in a university research laboratory. PARTICIPANTS: Ten healthy volunteers. INTERVENTIONS:Helmet continuous positive airway pressure and pressure support ventilation delivered by an ICU ventilator (closed-circuit ventilator) and two open-circuit ventilators equipped with a plateau valve placed either at the inspiratory or at the helmet expiratory port. MEASUREMENTS AND RESULTS: We measured helmet air leaks, breathing pattern, helmet minute ventilation (Eh)), minute ventilation washing the helmet (Ewh)), CO(2) wash-out, and ventilator inspiratory assistance. Air leaks were small and similar in all conditions. Breathing pattern was similar among the different ventilators. Inspiratory and end-tidal CO(2) were lower, while (Eh) and (Ewh) were higher only using open-circuit ventilators with the plateau valve placed at the helmet expiratory port. This occurred notwithstanding these ventilators delivered a lower inspiratory assistance. CONCLUSIONS: Additional helmet flow provided by open-circuit ventilators can lower helmet CO(2) rebreathing. However, inspiratory pressure assistance significantly decreases using open-circuit ventilators, still casting doubts on the choice of the optimal helmet ventilation setup.
RCT Entities:
OBJECTIVE: We examined whether additional helmet flow obtained by a single-circuit and a modified plateau valve applied at the helmet expiratory port (open-circuit ventilators) improves CO(2) wash-out by increasing helmet airflow. DESIGN AND SETTING: Randomized physiological study in a university research laboratory. PARTICIPANTS: Ten healthy volunteers. INTERVENTIONS: Helmet continuous positive airway pressure and pressure support ventilation delivered by an ICU ventilator (closed-circuit ventilator) and two open-circuit ventilators equipped with a plateau valve placed either at the inspiratory or at the helmet expiratory port. MEASUREMENTS AND RESULTS: We measured helmet air leaks, breathing pattern, helmet minute ventilation (Eh)), minute ventilation washing the helmet (Ewh)), CO(2) wash-out, and ventilator inspiratory assistance. Air leaks were small and similar in all conditions. Breathing pattern was similar among the different ventilators. Inspiratory and end-tidal CO(2) were lower, while (Eh) and (Ewh) were higher only using open-circuit ventilators with the plateau valve placed at the helmet expiratory port. This occurred notwithstanding these ventilators delivered a lower inspiratory assistance. CONCLUSIONS: Additional helmet flow provided by open-circuit ventilators can lower helmet CO(2) rebreathing. However, inspiratory pressure assistance significantly decreases using open-circuit ventilators, still casting doubts on the choice of the optimal helmet ventilation setup.
Authors: Fabrizio Racca; Lorenzo Appendini; Cesare Gregoretti; Elisa Stra; Antonio Patessio; Claudio F Donner; V Marco Ranieri Journal: J Appl Physiol (1985) Date: 2005-06-16
Authors: Paolo Navalesi; Roberta Costa; Piero Ceriana; Annalisa Carlucci; George Prinianakis; Massimo Antonelli; Giorgio Conti; Stefano Nava Journal: Intensive Care Med Date: 2006-10-13 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; Jerôme Pugin; Jan Wernerman; Haibo Zhang Journal: Intensive Care Med Date: 2009-01-06 Impact factor: 17.440