Effects of High-Intensity Inspiratory Muscle Training Following a Near-Fatal Gunshot Wound

Abstract

Background and Purpose: Severe injuries sustained during combat may classify individuals as undeployable for active service. It is imperative that every effort is made to optimize physical function following such injuries. Case Description: A 38-year-old man sustained a gunshot wound during armed combat. The bullet entered via the left axilla and exited from the right side of the abdomen, resulting in severe thoracic and abdominal injuries. Five months later, he continued to describe severe dyspnea on exertion. During a cardiopulmonary exercise test on a cycle ergometer, he achieved a maximum rate of oxygen uptake of 2,898 mL•min−1 (114% predicted) and maximum power of 230 W (114% predicted). His maximum forced inspiratory flow was 5.95 L•s−1, and inspiratory reserve volume at test end was ∼80 mL. The test was terminated by the patient due to dyspnea that was too severe to tolerate. Video fluoroscopy demonstrated impaired right hemidiaphragm function. The main goals of therapy were to reduce dyspnea on exertion and to enable return to full work duties. A program of high-intensity, interval-based threshold inspiratory muscle training (IMT) was undertaken. Outcomes: An average of 5 sessions of IMT were completed each week for 10 weeks. During a repeat cardiopulmonary exercise test, the patient achieved a similar power and maximum rate of oxygen uptake. His maximum forced inspiratory flow increased by 48% to 8.83 L•s−1, and he was limited by leg fatigue. Discussion: High-intensity IMT was safe and well tolerated. It was associated with improvements in maximum forced inspiratory flow and changed the locus of symptom limitation during high-intensity exercise from dyspnea to leg fatigue.