TY - JOUR
T1 - Maximal inspiratory pressure is not a reliable test of inspiratory muscle strength in mechanically ventilated patients
AU - Multz, A. S.
AU - Aldrich, T. K.
AU - Prezant, D. J.
AU - Karpel, J. P.
AU - Hendler, J. M.
PY - 1990
Y1 - 1990
N2 - Maximal inspiratory pressure (MIP) is an important clinical method used to assess respiratory muscle strength. The reliability and reproducibility of this measurement in mechanically ventilated patients is not certain. In 14 stable, mechanically ventilated patients, capable of spontaneous inspiratory efforts, we assessed maximal inspiratory efforts using the technique originally described by Marini and associates. MIP was measured in triplicate, by one to five experienced investigators, on one to seven successive days, for a total of 396 determinations on 54 patient days. The coefficients of variation among the triplicate efforts averaged 12 ± 1%, indicating the test to be highly reproducible. There was significant variation among the MIP reported by different investigators studying the same patient on the same day (32 ± 4%). The differences between best MIP by different investigators averaged 12.6 ± 1.3 cm H2O (40 ± 4%). In 17 of 44 cases, one investigator placed MIP above -30 cm H2O, whereas another placed it below. ANOVA showed that MIP was significantly affected by investigator (p < 0.0001) as well as by patient (p < 0.0001). Because 'true' MIP must be equal to or greater than the best measured MIP, these data indicate that the MIP is commonly underestimated in patients receiving mechanical ventilation, even when standardized technique is used. Furthermore, our data show that reproducibility of triplicate MIP determination by a single observer does not indicate that the test is reliable.
AB - Maximal inspiratory pressure (MIP) is an important clinical method used to assess respiratory muscle strength. The reliability and reproducibility of this measurement in mechanically ventilated patients is not certain. In 14 stable, mechanically ventilated patients, capable of spontaneous inspiratory efforts, we assessed maximal inspiratory efforts using the technique originally described by Marini and associates. MIP was measured in triplicate, by one to five experienced investigators, on one to seven successive days, for a total of 396 determinations on 54 patient days. The coefficients of variation among the triplicate efforts averaged 12 ± 1%, indicating the test to be highly reproducible. There was significant variation among the MIP reported by different investigators studying the same patient on the same day (32 ± 4%). The differences between best MIP by different investigators averaged 12.6 ± 1.3 cm H2O (40 ± 4%). In 17 of 44 cases, one investigator placed MIP above -30 cm H2O, whereas another placed it below. ANOVA showed that MIP was significantly affected by investigator (p < 0.0001) as well as by patient (p < 0.0001). Because 'true' MIP must be equal to or greater than the best measured MIP, these data indicate that the MIP is commonly underestimated in patients receiving mechanical ventilation, even when standardized technique is used. Furthermore, our data show that reproducibility of triplicate MIP determination by a single observer does not indicate that the test is reliable.
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U2 - 10.1164/ajrccm/142.3.529
DO - 10.1164/ajrccm/142.3.529
M3 - Article
C2 - 2389903
AN - SCOPUS:0025128319
SN - 0003-0805
VL - 142
SP - 529
EP - 532
JO - American Review of Respiratory Disease
JF - American Review of Respiratory Disease
IS - 3
ER -