Back to the drawing board: Exploring the composition and physical properties of traumatic hemothorax

BACKGROUND Despite a wide array of management options for traumatic hemothorax (HTX), rates of secondary intervention remain high. Exploring the composition and physical properties of HTX thrombi may inform improved management. We hypothesized that the composition and physical properties of HTX thrombi vary based upon time postinjury. METHODS Hemothorax samples were collected during resuscitative thoracotomy or thoracic surgical procedures for rib plating or retained HTX evacuation. Hemothorax thrombi were grouped according to the timing of collection (acute <72 hours postinjury vs. subacute ≥72 hours). Hemothorax compressive yield strength was quantified with rheometry, while composition and degree of contraction were determined using scanning electron microscopy. RESULTS Of eight HTX samples collected, five were acute (median collection, 0.5 hours postinjury [interquartile range, 0.5-0.6 hours]) and three were subacute (median collection, 108 hours postinjury [interquartile range, 77-128 hours]). Compressive yield strength was lower among acute HTX thrombi compared with subacute thrombi (median, 52.3 vs. 79.1 kPa; p = 0.01). Acute HTX thrombi exhibited a greater proportion of biconcave erythrocytes (11.0% vs. 4.0%, p = 0.006) but similar proportions of deformed erythrocytes and fibrin (38.8% vs. 42.1%, p = 0.226; 30.6% vs. 38.4%, p = 0.454). Acute HTX thrombi were also less contracted than subacute thrombi (median, 19.0% vs. 25.0%; p < 0.001). DISCUSSION The composition and physical properties of HTX thrombi vary significantly depending on the time postinjury. These findings support the use of early mechanical adjuncts to drainage including thoracic lavage. Retained HTX thrombi were significantly contracted and less porous, suggesting that lytic therapy could be enhanced with disruptive adjuncts such as lavage, ultrasound, or vibration. The timing of this transition and the effect on various interventions warrant further characterization.