Towards Portable Leg Perfusion: Initial Prototype Testing of a Selective Leg Perfusion System

Limb loss after combat injury is a major factor for morbidity in combat casualties. Although tourniquets clearly save lives, they can result in prolonged ischemia in large scale combat operations where evacuation from the point of injury is significantly delayed. We are developing a dedicated extracorporeal limb perfusion system suitable for organ preservation and present preliminary data on the feasibility of this approach. Amputated donor swine hindlimbs were perfused for 6 hours in a circulation system consisting of: containment unit, cardiotomy filter, peristaltic pump, with (OXY+) and without (OXY-) membrane oxygenator. Temperature, blood flow, pump revolutions per minute, and arterial blood gas analyses were performed hourly for 6 hours. Histology results were compared with limbs in cold storage. Statistics using SAS 9.4, 1-way mixed model with Dunnett correction and repeated measures mixed model with Tukey's adjustment (α = .05). Flow rates and pump settings were consistent. After 6 hours, the OXY+ group showed higher blood pH (7.38 ± 0.70 vs. 7.03 ± 0.7, P = .006), base excess (-15.8 ± 2.0 vs. -23.2 ± 1.8 mmol/L, P = .019) and oxygen saturation (64 ± 11% vs. 18 ± 4%, P = .003) compared to the OXY- group. Similarly, the pCO2 was lower in OXY+ (18.2 ± 2.1 vs. 27.6 ± 3.5 mmHg) compared to the OXY- group. Both groups showed an increase in potassium (OXY+: 6.2 ± 0.4 to 9.15 ± 0.70 mmol/L, P < .001; OXY-: 5.5 ± 0.2 to 10.3 ± 0.5 mmol/L, P < .001) and lactate (OXY+: 9.1 ± 1.3 to 15.9 ± 1.3 mmol/L, P < .001; OXY-: 6.7 ± 0.6 to 16.78 ± 0.83 mmol/L, P < .001), with no between group difference. Histological biopsy analysis showed a reduction of sarcoplasm and sarcolemma damage in the treatment group at 6 hours. Explanted limbs were successfully cannulated and perfused, and circulation was maintained at a constant flow rate with no adverse clotting events. Development of a purpose-built perfusion system is a promising avenue for limb preservation during large scale combat operations.