Diaphragmatic Dysfunction Is Characterized by Increased Duration of Mechanical Ventilation in Subjects With Prolonged Weaning.
BACKGROUND
Diaphragmatic dysfunction is often underdiagnosed and is among the risk factors for failed weaning. The purpose of this study was to determine the prevalence of diaphragmatic dysfunction diagnosed by B-mode ultrasonography and to determine whether prolonged weaning subjects with diaphragmatic dysfunction have increased duration of mechanical ventilation compared with those without diaphragmatic dysfunction.


METHODS
This was a prospective observational study in mechanically ventilated subjects who failed ≥3 spontaneous breathing trials or required >7 d of weaning after the first spontaneous breathing trial. Diaphragm thickness was measured in the zone of apposition using a 6-13-MHz ultrasound transducer during a spontaneous breathing trial. The diaphragmatic thickening fraction was calculated as a percentage from the formula: (Thickness at peak inspiration - thickness at end expiration)/thickness at end expiration. Intra-observer and inter-observer reliability were also evaluated.


RESULTS
Forty-one subjects (24 males; 62.2 ± 15.9 y old) were included in the study. Of these, the prevalence of ultrasonographic diaphragmatic dysfunction (defined as diaphragmatic thickening fraction of <20% with inspiration) was 34.1% (n = 14). Subjects with diaphragmatic dysfunction had longer ventilation time after inclusion (293.4 ± 194.8 vs 145.1 ± 101.3 h, P = .02) and ICU stay (29.2 ± 11.4 vs 22.4 ± 7.7 d, P = .03) than subjects without diaphragmatic dysfunction.


CONCLUSIONS
Diaphragmatic dysfunction as assessed by B-mode ultrasonography is common in subjects with prolonged weaning. Subjects with such diaphragmatic dysfunction show longer mechanical ventilation durations and ICU stays.
Department of Critical Care Medicine.
Zhihua
Z
Lu
Department of Critical Care Medicine.
Qiuping
Q
Xu
Department of Respiratory Care, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
Yuehua
Y
Yuan
Department of Critical Care Medicine.
Ge
G
Zhang
Department of Critical Care Medicine.
Feng
F
Guo
Department of Respiratory Care, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China. gehq@zju.edu.cn.
Huiqing
H
Ge
D000368:Aged; D003964:Diaphragm / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012119:Respiration; D012120:Respiration Disorders / Q000209:etiology / Q000503:physiopathology*; D012121:Respiration, Artificial / Q000009:adverse effects*; D012307:Risk Factors; D013997:Time Factors; D014463:Ultrasonography / Q000379:methods; D015300:Ventilator Weaning / Q000009:adverse effects*
diaphragm; intensive care units; mechanical ventilation; prevalence; ultrasonography; ventilator weaning