May - 2019
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Effect of Trans-Nasal Evaporative Intra-arrest Cooling on Functional Neurologic Outcome in Out-of-Hospital Cardiac Arrest - The PRINCESS Randomized Clinical Trial
JAMA, 2019, 321(17):1677-1685
There is probably a diverse range of opinions about therapeutic cooling after OHCA, from don’t believe in it, to advocating temperature management in a target from 32-36C for 24 to 72-hours. In addition, there is the question of pre-hospital cooling, and the technique used for cooling.
This RCT of 677 patients with OHCA examines the efficacy of intra-arrest trans-nasal cooling for adults with bystander witnessed OHCA. The possible benefits of intra-nasal evaporative cooling are avoidance of the volume and hemodynamic effects of cold saline, and the ability to be rapidly used in-arrest, with preferential cooling of the brain.
Patients randomised to cooling received a mixture of air or oxygen and a liquid coolant (perfluorohexane) via nasal catheters. As coolant evaporates it absorbs heat from surrounding tissue and rapidly cools the nasal cavity to about 2C. The method
was developed primarily to cool the brain because it takes advantage of the nasal pathways (ie, the conchal folds and turbinates) that provide a highly vascular and large, diffuse surface area that is in close proximity to the cerebral circulation. If ROSC occurred cooling was continued until hospital arrival.
Patients randomised to standard care received no cooling. All patients followed post-resuscitation guidelines including TTM.
What did they find;
Overall pre-hospital trans-nasal evaporative intra-arrest cooling did not result in an improvement in survival with good neurologic outcome for adult patients with OHCA. The subgroup analysis of patients with shockable rhythm revealed an area of further interest, ie incense in good recovery (CPC 1) in intervention vs control group. The authors note the intervention may have been too late, ie time to cooling was 105 minutes, after CPR. This was due to cooling being placed in secondary EMS vehicle.
Importance Therapeutic hypothermia may increase survival with good neurologic outcome after cardiac arrest. Trans-nasal evaporative cooling is a method used to induce cooling, primarily of the brain, during cardiopulmonary resuscitation (ie, intra-arrest).
Objective To determine whether prehospital trans-nasal evaporative intra-arrest cooling improves survival with good neurologic outcome compared with cooling initiated after hospital arrival.
Design, Setting, and Participants The PRINCESS trial was an investigator-initiated, randomized, clinical, international multicenter study with blinded assessment of the outcome, performed by emergency medical services in 7 European countries from July 2010 to January 2018, with final follow-up on April 29, 2018. In total, 677 patients with bystander-witnessed out-of-hospital cardiac arrest were enrolled.
Interventions Patients were randomly assigned to receive trans-nasal evaporative intra-arrest cooling (n = 343) or standard care (n = 334). Patients admitted to the hospital in both groups received systemic therapeutic hypothermia at 32°C to 34°C for 24 hours.
Main Outcomes and Measures The primary outcome was survival with good neurologic outcome, defined as Cerebral Performance Category (CPC) 1-2, at 90 days. Secondary outcomes were survival at 90 days and time to reach core body temperature less than 34°C.
Results Among the 677 randomized patients (median age, 65 years; 172 [25%] women), 671 completed the trial. Median time to core temperature less than 34°C was 105 minutes in the intervention group vs 182 minutes in the control group (P < .001). The number of patients with CPC 1-2 at 90 days was 56 of 337 (16.6%) in the intervention cooling group vs 45 of 334 (13.5%) in the control group (difference, 3.1% [95% CI, −2.3% to 8.5%]; relative risk [RR], 1.23 [95% CI, 0.86-1.72]; P = .25). In the intervention group, 60 of 337 patients (17.8%) were alive at 90 days vs 52 of 334 (15.6%) in the control group (difference, 2.2% [95% CI, −3.4% to 7.9%]; RR, 1.14 [95% CI, 0.81-1.57]; P = .44). Minor nosebleed was the most common device-related adverse event, reported in 45 of 337 patients (13%) in the intervention group. The adverse event rate within 7 days was similar between groups.
Conclusions and Relevance Among patients with out-of-hospital cardiac arrest, trans-nasal evaporative intra-arrest cooling compared with usual care did not result in a statistically significant improvement in survival with good neurologic outcome at 90 days.
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