Continuous positive airway pressure and ventilation are more effective with a nasal mask than a full face mask in unconscious subjects: a randomized controlled trial

Upper airway obstruction (UAO) is a major problem in unconscious subjects, making full face mask ventilation difficult. The mechanism of UAO in unconscious subjects shares many similarities with that of obstructive sleep apnea (OSA), especially the hypotonic upper airway seen during rapid eye moveme...

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Bibliographic Details
Published in:Critical care (London, England) England), 2013-12, Vol.17 (6), p.R300-R300, Article R300
Main Authors: Oto, Jun, Li, Qian, Kimball, William R, Wang, Jingping, Sabouri, Abdolnabi S, Harrell, Priscilla G, Kacmarek, Robert M, Jiang, Yandong
Format: Article
Language:English
Subjects:
Adolescent
Adult
Aged
Airway obstruction (Medicine)
Airway Obstruction - therapy
Artificial respiration
Care and treatment
Continuous positive airway pressure
Continuous Positive Airway Pressure - instrumentation
Diagnosis
Female
Health aspects
Humans
Male
Masks
Middle Aged
Tidal Volume
Unconsciousness
Young Adult
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Summary:Upper airway obstruction (UAO) is a major problem in unconscious subjects, making full face mask ventilation difficult. The mechanism of UAO in unconscious subjects shares many similarities with that of obstructive sleep apnea (OSA), especially the hypotonic upper airway seen during rapid eye movement sleep. Continuous positive airway pressure (CPAP) via nasal mask is more effective at maintaining airway patency than a full face mask in patients with OSA. We hypothesized that CPAP via nasal mask and ventilation (nCPAP) would be more effective than full face mask CPAP and ventilation (FmCPAP) for unconscious subjects, and we tested our hypothesis during induction of general anesthesia for elective surgery. In total, 73 adult subjects requiring general anesthesia were randomly assigned to one of four groups: nCPAP P0, nCPAP P5, FmCPAP P0, and FmCPAP P5, where P0 and P5 represent positive end-expiratory pressure (PEEP) 0 and 5 cm H2O applied prior to induction. After apnea, ventilation was initiated with pressure control ventilation at a peak inspiratory pressure over PEEP (PIP/PEEP) of 20/0, then 20/5, and finally 20/10 cm H2O, each applied for 1 min. At each pressure setting, expired tidal volume (Vte) was calculated by using a plethysmograph device. The rate of effective tidal volume (Vte > estimated anatomical dead space) was higher (87.9% vs. 21.9%; P
ISSN:1364-8535
1466-609X
1364-8535
DOI:10.1186/cc13169