Ultrasound: a novel translational tool to study diaphragmatic dysfunction in critical illness

Serial ultrasonographic monitoring of diaphragmatic and mid-upper arm muscle thickness in mechanically ventilated respiratory patients: A single-center observational study

INTRODUCTION

Muscle monitoring during mechanical ventilation (MV) is gaining great interest nowadays; however, a proper monitoring tool is not well-established yet.

OBJECTIVES

To assess the role of ultrasound in muscle monitoring during MV in respiratory patients.

METHODS

Eligible 68 mechanically ventilated patients were consecutively enrolled. Serial ultrasound measurements of diaphragmatic thickness at the end of inspiration (Tdi) and mid-upper arm (MUA) muscle thickness were recorded every other day till weaning. Before discharge, functional status score (FSS) was assessed.

RESULTS

Tdi decreased in 72.1%, did not change in 13.2% and increased in 14.7% of the patients. MUA muscle thickness decreased in 47.17% and did not change in others. Significant correlation between Tdi and MUA muscle thickness change was found (r = 0.404, P = 0.001); however, MUA muscle thickness change could not predict Tdi change (B = 0.067, P = 0.059). Diaphragmatic and MUA thickness change showed significant negative correlation with ICU stay (r = -0.260, -0.647, P = 0.032, <0.001) and MV duration (r = -0.335, -0.596, P = 0.005, <0.001), respectively. Weaning failure was significantly higher among patients with decreased Tdi (64.28%) and FSS was significantly lower in those with decreased MUA muscle thickness. US measurements of Tdi and MUA muscle thickness showed excellent intra-observer (ICC = 0.996, 0.999, P < 0.001) and inter-observer agreement (ICC = 0.992, 0.998, P < 0.001), respectively.

CONCLUSION

Sonographic muscle monitoring during MV is promising. Changes in the diaphragmatic thickness during MV are common and weakly related to those of peripheral muscles. Early decreased muscle thickness heralds poor weaning and functional outcome.

Point of care diaphragm ultrasound in infants with bronchiolitis: A prospective study

BACKGROUND

Bronchiolitis is the most common reason for hospitalization of children worldwide. Many scoring systems have been developed to quantify respiratory distress and predict outcome, but none of them have been validated. We hypothesized that the ultrasound evaluation of the diaphragm could quantify respiratory distress and therefore we correlated the ultrasound diaphragm parameters with outcome.

METHODS

Prospective study of infants with bronchiolitis (1-12 months) evaluated in a pediatric emergency department. Ultrasonography examinations of the diaphragm was performed (diaphragm excursion [DE], inspiratory excursion [IS], inspiratory/expiratory relationship [I/E], and thickness at end-expiration [TEE] and at end-inspiration [TEI]; thickening fraction [TF]).

RESULTS

We evaluated 61 infants, 50.8 % males. Mean TF was 47% (IQR 28.6-64.7), mean I/E 0.47 (± 0.15), mean DE 10.39 ± 4 mm. There was a linear correlation between TF and oxygen saturation at first evaluation (P = 0.006, r = 0.392). All children with lower values of TF required HFNC and one of them required CPAP. A higher IS was associated with the future need of respiratory support during admission (P = 0.007). IS correlated with the hours of oxygen delivery needed (P = 0.032, r = 0.422). TEI (t = 3.701, P = 0.002) was found to be main predictor of hours of oxygen delivery needed.

CONCLUSION

This study described ultrasound diaphragmatic values of previously healthy infants with bronchiolitis. DE, IS, and TEI correlated with outcome. If confirmed in larger studies, bedside ultrasound semiology of the diaphragm can be a new objective tool for the evaluation and outcome prediction of infants with bronchiolitis.