D. N. O’Hara1, S. Randazzo1, S. Ahmad1, D. Pasternak1, E. Huang1, R. Jawa1 1Stony Brook University Medical Center,Trauma And Critical Care,Stony Brook, NY, USA
Introduction: Rib fractures following blunt trauma are a major cause of morbidity. Patient age, number of rib fractures, presence of pulmonary contusion, and inspiratory capacity (IC) have all been used to assist in resource allocation. In medical patients, ultrasound measurements of diaphragm thickness have been previously shown to efficiently represent relative diaphragm function by way of the calculated diaphragm thickening fraction (TF). We sought to evaluate the feasibility of incorporating TF into the evaluation of this patient population.
Methods: This prospective, IRB-approved study enrolled adults (age ≥18 years) who were admitted to a level 1 ACS trauma center with blunt traumatic rib fractures. Exclusion criteria included injuries requiring a chest tube and mechanical ventilation at study enrollment. We evaluated TF and IC within 48 hours of admission. The TF was determined by measuring the minimum and maximum diaphragm thickness (Tdi) during spontaneous tidal breathing and calculating the TF ratio (TF= (Tdimaximum-Tdiminimum)/Tdiminimum). Inspiratory Capacity was determined via bedside incentive spirometry as the maximum recorded IC of 5 attempts.
Results: Twenty-five subjects (15 male, 10 female) were enrolled in the study. Demographic characteristics of this pilot sample include a median age of 59 (IQR 51.5-73.5) years, median Injury Severity Score of 10 (IQR 10-14), and BMI of 29.0 (IQR 26.44-31.66). Five patients had pulmonary contusions. One patient had lung disease and 8 patients were current smokers. Nine patients had ≥2 comorbidities. Each complete bedside evaluation (i.e. IC and TF) by trained medical students was completed in fewer than 10 minutes. Diaphragm ultrasound evaluation required approximately 5 minutes for accurate measurements. All patients tolerated the procedure. The median TF was 0.31 (IQR 0.24-0.45). The median IC was 1875 mL (IQR 1250-2438). The median hospital LOS was 3 days (IQR 3-5). No patients required mechanical ventilation during hospitalization and no patients had a complication.
Conclusion: Bedside ultrasound, as part of the eFAST exam, is commonly used to assess blunt trauma patients. Incorporation of diaphragmatic thickening fraction as part of the ultrasound exam could be rapidly accomplished. In this feasibility study, as no patients required mechanical ventilation nor developed any respiratory complications, correlation with these outcomes was not possible. Given its ease and feasibility, patients are now being enrolled to evaluate association with outcomes. With validation, diaphragm thickening fraction, an objective measure of pulmonary mechanics, could be used to identify patients at increased risk of respiratory failure.