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Inspiratory muscle effort during nasal intermittent positive pressure ventilation in patients with chronic obstructive airways disease
Author(s) -
ELLIOTT M. W.,
MULVEY D. A.,
MOXHAM J.,
GREEN M.,
BRANTHWAITE M. A.
Publication year - 1993
Publication title -
anaesthesia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.839
H-Index - 117
eISSN - 1365-2044
pISSN - 0003-2409
DOI - 10.1111/j.1365-2044.1993.tb06782.x
Subject(s) - medicine , ventilation (architecture) , anesthesia , respiratory system , peak inspiratory pressure , mechanical ventilation , respiratory minute volume , cardiology , tidal volume , mechanical engineering , engineering
Summary Effective intermittent positive pressure ventilation can be achieved noninvasively using a nasal mask, but patient comfort may be compromised and respiratory effort increased unless the trigger threshold is low and the response time of the ventilator short. The effect of nasal ventilation upon inspiratory muscle effort and the functional characteristics of the trigger of a purpose‐built ventilator were evaluated in five patients with chronic obstructive airways disease. A measure of inspiratory muscle effort, the average pressure time integral per minute, decreased by at least 80% in four patients and by 50% in one. Only two patients had significant numbers of triggered breaths (17% and 47% of total) during I h of ventilation with settings as used at home. Therefore trigger function was evaluated when the patients were made to trigger the ventilator by slowing the control rate. A high resting end‐expiratory intrathoracic pressure decreased the effective trigger sensitivity so that a mean (SD) change in oesophageal pressure of 14.8 (4.8) cmH 2 O was required to lower mask pressure by 2.4 (0.3) cmH 2 O and activate the trigger. Even under these conditions of lowest trigger sensitivity inspiratory muscle effort was not increased compared to spontaneous ventilation.