Change in diaphragm and intercostal muscle thickness in mechanically ventilated patients: a prospective observational ultrasonography study

Nobuto Nakanishi,Yoshitoyo Ueno,Taiga Itagaki,Masaji Nishimura,Emiko Nakataki,Jun Oto

doi:10.1186/s40560-019-0410-4

Abstract

BackgroundDiaphragm atrophy is observed in mechanically ventilated patients. However, the atrophy is not investigated in other respiratory muscles. Therefore, we conducted a two-center prospective observational study to evaluate changes in diaphragm and intercostal muscle thickness in mechanically ventilated patients.MethodsConsecutive adult patients who were expected to be mechanically ventilated longer than 48 h in the ICU were enrolled. Diaphragm and intercostal muscle thickness were measured on days 1, 3, 5, and 7 with ultrasonography. The primary outcome was the direction of change in muscle thickness, and the secondary outcomes were the relationship of changes in muscle thickness with patient characteristics.ResultsEighty patients (54 males and 26 females; mean age, 68 ± 14 years) were enrolled. Diaphragm muscle thickness decreased, increased, and remained unchanged in 50 (63%), 15 (19%), and 15 (19%) patients, respectively. Intercostal muscle thickness decreased, increased, and remained unchanged in 48 (60%), 15 (19%), and 17 (21%) patients, respectively. Decreased diaphragm or intercostal muscle thickness was associated with prolonged mechanical ventilation (median difference (MD), 3 days; 95% CI (confidence interval), 1–7 and MD, 3 days; 95% CI, 1–7, respectively) and length of ICU stay (MD, 3 days; 95% CI, 1–7 and MD, 3 days; 95% CI, 1–7, respectively) compared with the unchanged group. After adjusting for sex, age, and APACHE II score, they were still associated with prolonged mechanical ventilation (hazard ratio (HR), 4.19; 95% CI, 2.14–7.93 and HR, 2.87; 95% CI, 1.53–5.21, respectively) and length of ICU stay (HR, 3.44; 95% CI, 1.77–6.45 and HR, 2.58; 95% CI, 1.39–4.63, respectively) compared with the unchanged group.ConclusionsDecreased diaphragm and intercostal muscle thickness were frequently seen in patients under mechanical ventilation. They were associated with prolonged mechanical ventilation and length of ICU stay.Trial registrationUMIN000031316. Registered on 15 February 2018

Highlights

Diaphragm atrophy is observed in mechanically ventilated patients
Our study found that atrophy of diaphragm or intercostal muscles was associated with prolonged mechanical ventilation and length of intensive care unit (ICU) stay
In contrast to previous studies reporting the incidence of diaphragm atrophy at 41–44% [1, 5], 63% of the patients in the current study had decreased diaphragm thickness, which we propose might be due to two Change in diaphragm thickness

Summary

Introduction

Diaphragm atrophy is observed in mechanically ventilated patients. The atrophy is not investigated in other respiratory muscles. We conducted a two-center prospective observational study to evaluate changes in diaphragm and intercostal muscle thickness in mechanically ventilated patients. Ill patients experience atrophy of various muscles including respiratory muscles, with diaphragm muscle atrophy garnering increasing attention. Patients undergoing prolonged mechanical ventilation experience sustained diaphragm muscle loss, which leads to worse clinical outcomes [1]. Mechanical ventilation can affect the diaphragm and the intercostal muscles, as demonstrated in animal studies [2]. When respiratory workload increases, other respiratory muscles are more active than the diaphragm [3]. Intercostal muscles are one of the most important respiratory muscles in manipulating the movement of the rib cage [4]

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Results

Conclusion