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PRINCESS: Transnasal cooling safe, may improve outcomes in out-of-hospital cardiac arrest
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CHICAGO — Transnasal evaporative cooling initiated during CPR in patients with out-of-hospital cardiac arrest before they arrived at the hospital was hemodynamically safe as it shortened the time to target temperature, according to data presented at the American Heart Association Scientific Sessions.
The primary outcome of a Cerebral Performance Category score of 1 or 2 at 90 days was not statistically significant between the intervention and control groups, although patients with ventricular fibrillation who received the transnasal evaporative cooling device (RhinoChill, Benechill Inc.) had improved neurologic outcomes and were more likely to have improved complete recovery, according to the presentation.
“What we have done in this trial, we have used a completely different method called transnasal evaporative cooling,” Per Nordberg, MD, PhD, of the Center for Resuscitation Science at Karolinska Institutet in Stockholm, said during the presentation. “It cools primarily the brain. It’s a method where you insert a nasal catheter into the nasal cavity and deliver a spray, a mixture of oxygen and coolant. It cools very rapidly the surrounding tissue and also the blood circulation going to the brain. This is a noninvasive method. You can apply it wherever you are. In this trial, it was the scene of the arrest, but you can also start at the ER, cath lab and X-ray, depending on where you are with the patient.”
Researchers analyzed data from 677 patients (median age, 65 years; 75% men) with out-of-hospital cardiac arrest in Europe between 2010 and 2018. Patients were assigned either prehospital cooling with the transnasal evaporative cooling device (n = 343) or standard care (n = 334). Both groups received systemic cooling once they arrived at the hospital.
The primary outcome was survival with a Cerebral Performance Category score of 1 or 2 at 90 days.
“[Cerebral Performance Category] 1 and 2 was considered traditionally as a good outcome,” Nordberg said during the presentation. “However, there’s a big difference between those two groups. [Cerebral Performance Category] 1 is complete neurologic recovery. You can go back to the activity you had prior to the arrest. ... [Cerebral Performance Category] 2, you can do some independent activities and you can work in a sheltered environment.”
Of the patients in the study, 60% received bystander CPR and 40% had ventricular fibrillation. CPR initiated by emergency medical services occurred at a median of 9 minutes, and an airway was established within 14 minutes. Patients underwent randomization at 17 minutes and cooling was initiated at 19 minutes.
The time to target temperature was 101 minutes in the intervention group and 182 minutes in the control group (P < .001).
Device-related events in the intervention group included prolonged nosebleed (1%), minor nosebleed (14%) and white nose tip (6%).
Complications within 7 days in patients assigned the intervention or to the control group included ventricular fibrillation (2% vs. 4%, respectively), cardiogenic shock (22% vs. 24%, respectively), pulmonary edema (5% vs. 13%, respectively) and the requirement of a vasopressor (76% vs. 70%, respectively).
The primary outcome occurred in 16.6% of patients in the intervention group and 13.5% in the control group (absolute difference = 3.1%; relative difference = 23%; P = .26). In patients with ventricular fibrillation, the primary outcome was seen in 34.8% of patients assigned the intervention compared with 25.9% of those assigned the control (absolute difference = 8.9%; relative difference = 25%; P = .11).
“We have no statistically significant difference in the whole population, but there is a signal in the ventricular fibrillation group towards a benefit in the primary outcome,” Nordberg said during the presentation.
Complete neurologic recovery occurred in 32.6% of patients in the intervention group vs. 20% in the control group (P = .02). Of the patients with ventricular fibrillation, 14.8% assigned the intervention and 10.5% assigned the control had complete neurologic recovery (P = .09).
In patients who were alive at 90 days in the intervention (n = 60) and control groups (n = 52), a Cerebral Performance Category score of 1 was achieved in 50 patients assigned the intervention and 35 patients in the control group.
“As guidelines are stated at the moment, you should not cool the patient outside of the hospital,” Nordberg said during the presentation. “We have shown that this is possible with this new method.”
“This well-conducted trial confirmed that patients can be safely and rapidly cooled early and during arrest, but we still do not know if this has meaningful improvement in clinical outcome,” Christopher B. Granger, MD, professor of medicine, professor in the school of nursing and member in the Duke Clinical Research Institute at Duke University School of Medicine, said during the discussant portion of the presentation. – by Darlene Dobkowski
Reference:
Nordberg P, et al. LBS.04 – Preserving Brain & Heart in Acute Care Cardiology. Presented at: American Heart Association Scientific Sessions; Nov. 10-12, 2018; Chicago.
Disclosures: The device used in this study was provided without cost to the sites. Nordberg reports he received research grants from The Swedish Heart and Lung Foundation. Granger reports he is a consultant/advisory board member for Abbvie, Armetheon, AstraZeneca, Bayer, Boehringer Ingelheim, Boston Scientific, Bristol-Myers Squibb, Daiichi Sankyo, Gilead Sciences, GlaxoSmithKline, Janssen Pharmaceuticals, Medtronic, Merck, NIH, Novartis, Novo Nordisk, Pfizer, Rho Pharmaceuticals, Sirtex and Verseon and received research grants from Armetheon, AstraZeneca, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Daiichi Sankyo, Duke Clinical Research Institute, the FDA, GlaxoSmithKline, Janssen Pharmaceuticals, Medtronic Foundation, Novartis, Pfizer.
Perspective
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Marco Perez, MD
These are really exciting data. The researchers were hoping to show differences in survival with good cerebral function. There was a measurable difference, but it was not statistically significant. However, there are some secondary analyses performed that show great promise.
The most important secondary finding is that the degree of brain recovery in the group that received the cooling in the field was much better in those who ended up surviving. It was a secondary analysis. That was not the main purpose of the study, but it is something that is promising. The researchers are going to need to conduct further studies to verify that since it was not their primary analysis, but that is one of the more exciting aspects of the study.
In these patients who have a cardiac arrest and then go on to survive, one of the most important aspects of their survival is how much brain recovery they’ve had. If you can do something to improve the amount of brain recovery, if it is proven to really work as well as their secondary analyses suggest, that could lead to the use of technologies like transnasal cooling in the field. It could have a direct impact if this secondary analysis is verified.
Also of interest is another secondary analysis where there was a trend toward greater survival with good brain function in ventricular fibrillation arrest patients. Again, it was not statistically significant, it was not the primary analysis, but that is another question that the study brings up that needs to be studied further.
Also, it makes you wonder if there are other groups of patients who are may not benefit from transnasal cooling in the field. If the overall effect of a study is null, but there’s a subgroup that benefits, it is possible that there is another subgroup that is not benefitting or maybe even having some harm caused to them. That can be a cautionary note. We just have to be careful in thinking about which patients are best going to be served by cooling technologies in the field.
Stanford University Medical Center
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