Supine fall in lung volumes in the assessment of diaphragmatic weakness in neuromuscular disorders.
OBJECTIVE
To determine whether diaphragmatic function can be determined by noninvasive respiratory indices in neuromuscular disease.


METHODS
Vital capacity (VC) and mouth pressure generated during a maximal static inspiratory effort (Pi max) were measured with patients in both sitting and supine positions.


METHODS
Rehabilitation hospital.


METHODS
Twenty-four patients with generalized neuromuscular disease.


METHODS
Changes in indices from sitting to supine position were compared with invasive diaphragmatic function indices consisting of transdiaphragmatic pressures during maximal sniff (Pdi sniff) and the ratio of gastric pressure (Pga) increases over transdiaphragmatic pressure (DeltaPga/DeltaPdi) during quiet breathing.


RESULTS
The fall in VC in the supine position was greater in the 15 patients who had spontaneous paradoxical diaphragmatic motion (DeltaPga/DeltaPdi < 0) than in the 9 patients who did not. Specificity and sensitivity of a greater than 25% supine fall in VC for the diagnosis of diaphragmatic weakness (DeltaPga/DeltaPdi < 0 and/or Pdi sniff < 30cmH2O) were 90% and 79%, respectively. Stepwise multiple regression analysis of Pdi sniff showed that both the supine fall in VC and Pi max were associated with diaphragmatic weakness (R(2) =.66; p <.0001). These factors contributed 52% and 14% of the Pdi sniff variance, respectively.


CONCLUSIONS
Simple VC measurement in the sitting and supine positions may be helpful in detecting severe or predominant diaphragmatic weakness.
Service de Physiologie-Explorations Fonctionnelles, Hôpital Raymond Poincaré, Garches, France.
C
C
Fromageot
F
F
Lofaso
D
D
Annane
L
L
Falaize
M
M
Lejaille
B
B
Clair
P
P
Gajdos
J C
JC
Raphaël
D000328:Adult; D000368:Aged; D002648:Child; D003964:Diaphragm / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009468:Neuromuscular Diseases / Q000503:physiopathology*; D012044:Regression Analysis; D013147:Spirometry; D018709:Statistics, Nonparametric; D016683:Supine Position; D014797:Vital Capacity