title: Head helmet versus face mask for non-invasive continuous positive airway pressure: a physiological study.
abstract: OBJECTIVE
  To assess selected physiological effects of non-invasive continuous positive airway pressure delivered by head helmet (CPAPH), a special interface device designed to completely contain the head of the patient, compared to face mask (CPAPM).
  
  
  METHODS
  Randomized physiological study.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  Eight healthy volunteers.
  
  
  METHODS
  Continuous positive airway pressure delivered by face mask and CPAPH in random order. Three gas flow rates (20-30-40 l/min and 30-45-60 l/min, respectively, for CPAPM and CPAPH) and four CPAP levels (0-5-10-15 cmH2O) were employed in a randomized sequence.
  
  
  RESULTS
  In each patient we monitored airway pressure, esophageal pressure, expiratory flow, and inspiratory and expiratory CO2 concentration. End-expiratory lung volume changes from CPAP 0 were measured by inductance plethysmography. The application of increased levels of CPAP resulted in a significant increase in end-expiratory lung volume, similar for CPAPH and CPAPM. Inspiratory changes of airway pressure were comparable for the two CPAP modes. Inspiratory CO2 concentration was higher during CPAPH (significantly decreased at increased gas flow rates), compared to CPAPM.
  
  
  CONCLUSIONS
  Continuous positive airway pressure delivered by head helmet is as effective as CPAPM in increasing end-expiratory lung volume and in compensating for airway pressure changes without the need of a reservoir bag. Higher gas flow rates are necessary to maintain a relatively low inspiratory CO2 concentration.
authors.affiliation: Department of Anesthesia and Intensive Care, Ospedale San Gerardo Nuovo dei Tintori, University of Milano-Bicocca, Via Donizetti 106, 20052 Monza (Milano), Italy. nicolo.patroniti@unimib.it
authors.forename: Nicolò
authors.initials: N
authors.lastname: Patroniti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Foti
authors.forename: Annamaria
authors.initials: A
authors.lastname: Manfio
authors.forename: Anna
authors.initials: A
authors.lastname: Coppo
authors.forename: Giacomo
authors.initials: G
authors.lastname: Bellani
authors.forename: Antonio
authors.initials: A
authors.lastname: Pesenti
mesh_terms: D000328:Adult; D045422:Continuous Positive Airway Pressure / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008397:Masks; D012123:Pulmonary Ventilation; D012119:Respiration