Use of Auto Transfusion Tourniquet increases end-tidal-CO₂ in out-of-hospital cardiac arrest patients - a feasibility...

Out-of-hospital cardiac arrest (OHCA) remains a leading cause of mortality, with low survival rates despite advancements in cardiopulmonary resuscitation (CPR) and emergency care. This study aimed to evaluate the safety and effectiveness of the HemaShock® Auto-Transfusion Tourniquet (A-TT) in OHCA patients by assessing its impact on ACLS quality, ROSC rate and end-tidal CO₂ partial pressure (PetCO₂).

This was a feasibility pilot study conducted in the pre-hospital setting of Maribor, Slovenia. The study was registered at ClinicalTrials.org #NCT06153160 and was approved by the Institutional Ethics Committee. Twenty-four OHCA patients were enrolled and divided into two groups: 12 patients received standard advanced cardiac life support (ACLS) plus A-TT (Study Group), while 12 received only ACLS (Control Group). The primary efficacy outcome was the difference in PetCO₂ before and after A-TT application in the Study Group. The primary safety outcome was assessed by evaluating the standard quality parameters of CPR in the two groups and by verifying that the rate of ROSC in the Study Group was not lower than in the Control Group.

There were no significant demographic differences between the two groups.. A-TT was successfully applied in 12 patients, with one case being ineffective. Return of spontaneous circulation (ROSC) was achieved in 50 % of the Study Group and 33 % of the Control Group (NS). PetCO₂ increased by 24.8 % (P < 0.005) immediately after A-TT application, sustaining for 5 min before returning to baseline. No adverse effects on ACLS delivery quality or patient management were observed.

The use of A-TT in OHCA patients did not interfere with ACLS protocols and did not reduce ROSC rate. The significant transient increase in PetCO₂ may be due to shifting of CO₂-loaded blood from the legs to the core by the A-TT, or due to improved tissue perfusion and O₂ delivery during resuscitation. Earlier application of A-TT may enhance its effect on outcome. Further randomized controlled studies with larger sample sizes are needed to assess its impact on survival and neurological outcomes.

The pilot study was registered into Clinical Trials in February 2023. The trial number is NCT06153160. The trial protocol can be assessed through the webpage cinicaltrials.gov.org.