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Measurement of maximal inspiratory pressure in ventilated children
Author(s) -
Harikumar Gopinathannair,
Moxham John,
Greenough Anne,
Rafferty Gerrard F.
Publication year - 2008
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.20905
Subject(s) - medicine , functional residual capacity , expiration , lung volumes , residual volume , occlusion , anesthesia , cardiology , airway , ventilation (architecture) , respiratory system , lung , mechanical engineering , engineering
Maximal inspiratory pressure (PIMAX), the maximum negative pressure generated during temporary occlusion of the airway, is commonly used to measure inspiratory muscle strength in mechanically ventilated infants and children. There are, however, no guidelines as to how the PIMAX measurement should be made. We compared the maximum inspiratory pressure generated during airway occlusion (PIMAX OCC ) to that when a unidirectional valve (PIMAX UNI ), which allowed expiration, but not inspiration was used. Twenty‐two mechanically ventilated children (mean (SD) age 4.8 (4.5) years) were studied. Three sets of end expiratory occlusions were performed for each method in random order. The expired volume during PIMAX UNI was assessed and related to the functional residual capacity (FRC) measured using a helium dilution technique. The mean (SD) PIMAX UNI (45.5 (15.2) cmH 2 O) was significantly greater than mean (SD) PIMAX OCC (30.9 (9.0) cmH 2 O) ( P < 0.0001). The mean (SD) expired volume during PIMAX UNI , was 98 ml (62.3), a mean reduction in FRC of 33.1% (SD 13.9). There were no significant differences between techniques in the baseline respiratory drive, the number of efforts required and the time to reach PIMAX. Regardless of technique, PIMAX was reached in 10 inspiratory efforts or 15 sec of airway occlusion. A unidirectional valve allowing expiration, but not inspiration yields greater PIMAX values in children. Occlusions should be maintained for 12 sec or eight breaths (99% CI of mean). Pediatr. Pulmonol. 2008; 43:1085–1091. © 2008 Wiley‐Liss, Inc.