The Maximal Expiratory-to-Inspiratory Pressure Ratio and Supine Vital Capacity as Screening Tests for Diaphragm Dysfunction.
The change in vital capacity from the seated to supine position (∆VC-supine) is used to screen for diaphragm dysfunction (DD), but some individuals are unable to tolerate the supine position. Since expiratory muscle function is often preserved in patients with isolated DD and inspiratory strength is reduced, the purpose of this study was to examine if the ratio of maximal expiratory pressure to maximal inspiratory pressure (MEP/MIP) may provide an alternative to ∆VC-supine when screening patients for DD.



We performed a cross-sectional analysis on 76 patients referred for evaluation of unexplained dyspnea and possible DD. MEP and MIP were measured in the seated position as well as the percent change in VC from the seated to supine position (∆VC-supine %). The presence of unilateral diaphragm paralysis (UDP), bilateral diaphragm paralysis (BDP), or normal diaphragm function (N) was confirmed by ultrasound.



Of the 76 patients, 23 had N, 40 had UDP, and 13 had BDP. MEP/MIP was significantly greater for UDP compared to N (2.1(1.2-5.7) and 1.5(0.7-2.2), respectively) (median and interquartile range) and for BDP compared to UDP (4.3(2.3-7.5) and 2.1(1.2-5.7), respectively) (p < 0.001). The area (AUC) under the receiver-operating characteristic curve for MEP/MIP between N and UDP was 0.84 (95% confidence interval (CI) 0.74-0.94) and between UDP and BDP was 0.90 (95% CI 0.80-0.99). MEP/MIP had a strong monotonic relationship with ∆VC-supine % (Spearman's ρ = 0.68, p < 0.001).



The MEP/MIP ratio provides a method with comparable sensitivity and specificity to ∆VC-supine % that can be used to screen patients with suspected isolated phrenic neuropathy and alleviates the need for measuring supine pulmonary function.
Department of Pulmonary, Critical Care, and Sleep Medicine, Alpert Medical School of Brown University and Memorial Hospital of Rhode Island, 111 Brewster Street 3rd Floor, Pawtucket, RI, 02860, USA.
Patrick
P
Koo
Department of Pulmonary, Critical Care, and Sleep Medicine, Alpert Medical School of Brown University and Memorial Hospital of Rhode Island, 111 Brewster Street 3rd Floor, Pawtucket, RI, 02860, USA.
Dennis O
DO
Oyieng'o
Department of Pulmonary, Critical Care, and Sleep Medicine, Alpert Medical School of Brown University and Memorial Hospital of Rhode Island, 111 Brewster Street 3rd Floor, Pawtucket, RI, 02860, USA.
Eric J
EJ
Gartman
Department of Pulmonary, Critical Care, and Sleep Medicine, Alpert Medical School of Brown University and Memorial Hospital of Rhode Island, 111 Brewster Street 3rd Floor, Pawtucket, RI, 02860, USA.
Jigme M
JM
Sethi
Department of Family Medicine and Epidemiology, Alpert Medical School of Brown University and Memorial Hospital of Rhode Island, 111 Brewster Street 2nd Floor, Pawtucket, RI, 02860, USA.
Charles B
CB
Eaton
Division of Pulmonary, Critical Care, and Sleep, Alpert Medical School of Brown University, Memorial Hospital of Rhode Island, 111 Brewster Street, 3rd Floor, Pawtucket, RI, 02860, USA. f_mccool@brown.edu.
F Dennis
FD
McCool
D000368:Aged; D019540:Area Under Curve; D003430:Cross-Sectional Studies; D003964:Diaphragm / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004417:Dyspnea / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D000072277:Maximal Respiratory Pressures; D008875:Middle Aged; D012372:ROC Curve; D012133:Respiratory Paralysis / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D016683:Supine Position / Q000502:physiology; D014463:Ultrasonography; D014797:Vital Capacity
Diaphragm; Diaphragm paralysis; Pulmonary function testing; Respiratory measurement; Respiratory muscles