Prevalence and outcome of diaphragmatic dysfunction assessed by ultrasound technology during acute exacerbation of chronic obstructive pulmonary disease: a pilot study.

Background. The prevalence and clinical consequences of diaphragmatic dysfunction (DD) during acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are still not known. The aim of this study was a) to evaluate the prevalence of DD as assessed by ultrasonography, b) to report the impact of DD on non-invasive ventilation (NIV) failure, length of hospital stay, and short and long-term mortality in severe AECOPD patients admitted to intensive care. Method. Forty one consecutive patients with AECOPD and respiratory acidosis admitted over a 12 month period to the respiratory Intensive Care Unit (ICU) of the University Hospital of Modena were studied. Diaphragmatic ultrasound was performed on admission before starting NIV. A change of diaphragm thickness (ΔTdi) less than 20% during spontaneous breathing was considered to confirm the presence of dysfunction (DD+). NIV failure and other clinical outcomes (duration of MV, tracheostomy, length of hospital stay and mortality ) were also recorded. Results. Ten out of 41 patients (24.3%) presented DD+, which was significantly associated with steroid use (p=0.002, R-squared=0.19). DD+ was found to correlate with NIV failure (p<0.001, R-squared=0.27), longer ICU stay (p=0.02, R-squared=0.13), prolonged mechanical ventilation (p=0.023, R-squared=0.15) and need for tracheostomy (p=0.006, R-squared=0.20). Moreover, the Kaplan-Meyer survival estimates showed that NIV failure (log-rank=0.001) and mortality in respiratory ICU (log-rank=0.039) were significantly associated with DD+. Conclusions. In AECOPD patients hospitalised and submitted to NIV, severe dysfunction of the diaphragm was seen in almost a quarter of patients. Dysfunction of the diaphragm may cause NIV failure, and impact on the use of clinical resources and on the patient’s short-term mortality.