Mechanical Ventilation and Diaphragmatic Atrophy in Critically Ill Patients: An Ultrasound Study

Objective: Mechanical ventilation contributes to diaphragmatic atrophy and dysfunction, and few techniques exist to assess diaphragmatic function: the purpose of this study was to quantify diaphragm atrophy in a population of critically ill mechanically ventilated patients with ultrasound and to identify risk factors that can worsen diaphragmatic activity. Design: Prospective observational study. Setting: ICU of a 1,200-bed university hospital. Patients: Newly intubated adult critically ill patients. Interventions: Diaphragm thickness in the zone of apposition was measured daily with ultrasound, from the first day of mechanical ventilation till discharge to the main ward. Measurements and Main Results: Daily atrophy rate (&Dgr;Tdi/d) was calculated as the reduction in percentage from the previous measurement. To analyze the difference in atrophy rate (&Dgr;Tdi/d), ventilation was categorized into four classes: spontaneous breathing or continuous positive airway pressure; pressure support ventilation 5–12 cm H2O (low pressure support ventilation); pressure support ventilation greater than 12 cm H2O (high pressure support ventilation); and controlled mechanical ventilation. Multivariate analysis with ventilation support and other clinical variables was performed to identify risk factors for atrophy. Forty patients underwent a total of 153 ultrasonographic evaluations. Mean (SD) &Dgr;Tdi/d was –7.5% (12.3) during controlled mechanical ventilation, –5.3% (12.9) at high pressure support ventilation, –1.5% (10.9) at low pressure support ventilation, +2.3% (9.5) during spontaneous breathing or continuous positive airway pressure. At multivariate analysis, only the ventilation support was predictive of diaphragm atrophy rate. Pressure support predicted diaphragm thickness with coefficient –0.006 (95% CI, –0.010 to –0.002; p = 0.006). Conclusions: In critically ill mechanically ventilated patients, there is a linear relationship between ventilator support and diaphragmatic atrophy rate.

[1]  W. Yost,et al.  Diaphragmatic thickness-lung volume relationship in vivo. , 1989, Journal of applied physiology.

[2]  G. Rubenfeld,et al.  Measuring diaphragm thickness with ultrasound in mechanically ventilated patients: feasibility, reproducibility and validity , 2015, Intensive Care Medicine.

[3]  H. Grosu,et al.  Diaphragm muscle thinning in patients who are mechanically ventilated. , 2012, Chest.

[4]  S. Eveloff,et al.  Diaphragm thickening during inspiration. , 1997, Journal of applied physiology.

[5]  S. Powers,et al.  Rapid disuse atrophy of diaphragm fibers in mechanically ventilated humans. , 2008, The New England journal of medicine.

[6]  L. Heunks,et al.  Monitoring of the respiratory muscles in the critically ill. , 2013, American journal of respiratory and critical care medicine.

[7]  Saoussen Dimassi,et al.  Sonographic evaluation of the diaphragm in critically ill patients. Technique and clinical applications , 2013, Intensive Care Medicine.

[8]  S. Jaber,et al.  Rapid Onset of Specific Diaphragm Weakness in a Healthy Murine Model of Ventilator-induced Diaphragmatic Dysfunction , 2012, Anesthesiology.

[9]  T. Similowski,et al.  Diaphragm dysfunction on admission to the intensive care unit. Prevalence, risk factors, and prognostic impact-a prospective study. , 2013, American journal of respiratory and critical care medicine.

[10]  Luca Cabrini,et al.  Diaphragmatic Ultrasound in Critically Ill Patients , 2013 .

[11]  A. Zangrillo,et al.  Ultrasound in critically ill patients: focus on diaphragm , 2013, Intensive Care Medicine.

[12]  T. Vassilakopoulos,et al.  Ventilator-induced diaphragmatic dysfunction. , 2004, American journal of respiratory and critical care medicine.

[13]  Tossaporn Yimlamai,et al.  Mechanical ventilation-induced diaphragmatic atrophy is associated with oxidative injury and increased proteolytic activity. , 2002, American journal of respiratory and critical care medicine.

[14]  George Tomlinson,et al.  Evolution of Diaphragm Thickness during Mechanical Ventilation. Impact of Inspiratory Effort. , 2015, American journal of respiratory and critical care medicine.

[15]  Aissam Lyazidi,et al.  Diaphragm ultrasonography to estimate the work of breathing during non-invasive ventilation , 2012, Intensive Care Medicine.