A 22-year-old soldier sustains a stab wound to his chest during a military attack. The soldier reports shortness of breath. He is alert and oriented to time, place, and person. His pulse is 99/min, respirations are 32/min, and blood pressure is 112/72 mm Hg. Examination shows a 2-cm wound at the left fourth intercostal space at the midclavicular line. Bubbling of blood is seen with each respiration at the wound site. There is no jugular venous distention. There is hyperresonance to percussion and decreased breath sounds on the left side. The trachea is at the midline. Which of the following changes have most likely occurred in this patient's left hemithorax and left lung compared to his preinjury state?

Question

Quizplus · Accepted Answer

Eductional Objective: The lungs exert collapsing force, and the resting chest wall exerts expanding force.  These opposing forces are in equilibrium at the functional residual capacity and generate sustained intrapleural negative pressure that allows the lung and chest wall to move together as a combined respiratory unit.  Loss of intrapleural negative pressure (eg, pneumothorax) disrupts the combined system, causing the chest wall to spring outward to its equilibrium position, enlarging the hemithorax.  Similarly, the lung collapses to its equilibrium position where inspiratory compliance is decreased.

A 22-Year-Old Soldier Sustains a Stab Wound to His Chest