Olivier Bataille: No relevant disclosure to display
Background: In cardiogenic shock and during extracorporeal membrane oxygenation (ECMO), limb perfusion is affected by low cardiac output, vasopressor use, cannula size, distal perfusion catheters, and competing flows, yet bedside assessment remains indirect. We analyzed intramuscular pressure and temperature data from a limb ischemia model to characterize perfusion changes during ischemia-reperfusion.
Methods: A preclinical large animal model was used to examine limb perfusion under controlled ischemic and reperfusion conditions (n = 4). Arterial inflow to the hindlimb was mechanically reduced and subsequently restored, with the contralateral limb serving as a nonreperfused comparator. Intramuscular pressure and temperature were continuously measured within the muscle compartment using an implantable monitoring system. Systemic and regional hemodynamics were assessed via femoral arterial pressure monitoring. Additional physiologic data included intermittent near-infrared spectroscopy (NIRS), venous lactate sampling, and arterial blood gas analysis. All datasets were reviewed retrospectively, with a focus on the temporal relationships between intramuscular pressure trends, temperature changes, and other physiological measures during ischemia and reperfusion.
Outcome: Following restoration of arterial inflow, intramuscular pressure demonstrated a consistent, short-lived rise of 8–12 mmHg that developed within 20–40 minutes and was accompanied by increased pressure waveform pulsatility before returning toward baseline. Temperature recovery of 2–3 °C occurred after pressure normalization rather than concurrently. In contrast, oxygenation changes measured by NIRS were delayed, appearing up to 45 minutes later (mean ~35 ± 10 minutes). Limbs that did not undergo reperfusion showed neither sustained pressure elevation nor temperature recovery. During periods of reduced inflow, intramuscular pressure increased gradually over time despite stable limb temperature.
Conclusion: In this preclinical animal model, intramuscular monitoring detected reproducible compartment level ischemia and reperfusion responses earlier than surface oxygenation by NIRS. In cardiogenic shock and ECMO, where cannulation strategy, distal perfusion catheters, and competing flows determine limb perfusion, surface based monitoring may lag tissue level changes. Clinical validation is ongoing.
