Respiratory Musculature Evaluated by Computed Tomography in the Setting of Prolonged Mechanical Ventilation

BACKGROUND: Diaphragm atrophy has been observed in subjects who undergo invasive mechanical ventilation. We propose a new method to assess for respiratory muscle (RM) changes in subjects who undergo invasive mechanical ventilation by assessing for changes in respiratory muscles through computed tomography (CT).

METHODS: A retrospective case series study was conducted on subjects who underwent invasive mechanical ventilation and received at least 2 chest CT scans during admission. Exclusion criteria included history of chronic mechanical ventilation dependence and neuromuscular disease. Respiratory muscle cross-sectional area (CSA) was measured at the T6 vertebrae.

RESULTS: Fourteen subjects were included: mean (± SD) age, BMI, and admission APACHE II scores were 54.0 y (± 14.9), 32.6 kg/m² (± 10.9), and 23.5 (± 6.0), respectively. Ten (71%) subjects were male. Mean length of time between CT chest scans was 7.5 d (± 3.3). Mean duration of invasive mechanical ventilation was 4.5 d (± 3.4). The percentage change in TM CSA among those who underwent invasive mechanical ventilation was 10.5% (± 6.1).

CONCLUSIONS: We demonstrated that serial analysis of respiratory muscle CSA through CT chest scans can be a method to assess for respiratory muscle atrophy in subjects undergoing mechanical ventilation. Future prospective studies involving larger populations are needed to better understand how this method can be used to predict outcomes in mechanically ventilated patients.