Safety and feasibility of nasopharyngeal evaporative cooling in the emergency department setting in survivors of cardiac arrest

doi:10.1016/j.resuscitation.2010.04.027

Resuscitation

Volume 81, Issue 8, August 2010, Pages 943-949

https://doi.org/10.1016/j.resuscitation.2010.04.027 Get rights and content

Abstract

Aim

Mild therapeutic hypothermia improves survival and neurologic recovery in primary comatose survivors of cardiac arrest. Cooling effectivity, safety and feasibility of nasopharyngeal cooling with the RhinoChill device (BeneChill Inc., San Diego, USA) were determined for induction of therapeutic hypothermia.

Methods

Eleven emergency departments and intensive care units participated in this multi-centre, single-arm descriptive study. Eighty-four patients after successful resuscitation from cardiac arrest were cooled with nasopharyngeal delivery of an evaporative coolant for 1 h. Subsequently, temperature was controlled with systemic cooling at 33 °C. Cooling rates, adverse events and neurologic outcome at hospital discharge using cerebral performance categories (CPC; CPC 1 = normal to CPC 5 = dead) were documented. Temperatures are presented as median and the range from the first to the third quartile.

Results

Nasopharyngeal cooling for 1 h reduced tympanic temperature by median 2.3 (1.6; 3.0) °C, core temperature by 1.1 (0.7; 1.5) °C. Nasal discoloration occurred during the procedure in 10 (12%) patients, resolved in 9, and was persistent in 1 (1%). Epistaxis was observed in 2 (2%) patients. Periorbital gas emphysema occurred in 1 (1%) patient and resolved spontaneously. Thirty-four of 84 patients (40%) patients survived, 26/34 with favorable neurological outcome (CPC of 1–2) at discharge.

Conclusions

Nasopharyngeal evaporative cooling used for 1 h in primary cardiac arrest survivors is feasible and safe at flow rates of 40–50 L/min in a hospital setting.

Introduction

Sudden cardiac arrest is a major cause of death in the western world, and the estimated number of out-of-hospital cardiac arrest cases is 300,000/year in the US. The median rate of survival to hospital discharge in the US is 7.9%.¹ Favorable outcome of patients admitted to the hospital range between 11% and 48%,2, 3 indicating a large number of patients that die after successful resuscitation during the hospital stay, or develop sustained severe brain damage. Two randomized controlled trials4, 5 have demonstrated that mild therapeutic hypothermia (32–34 °C) for 12–24 h improves neurologic recovery and survival after cardiac arrest. The European Resuscitation Council and The American Heart Association recommend mild hypothermia for unconscious adult patients resuscitated from cardiac arrest due to ventricular fibrillation.6, 7 Animal data suggest that a delay in cooling may negate its beneficial effects,⁸ and a study by Wolff et al. demonstrated that early achievement of hypothermia is a determinant of favorable outcome in patients after cardiac arrest.⁹ Cooling methods are needed which can be applied early after restoration of spontaneous circulation (ROSC) and cool efficiently.

The RhinoChill device (BeneChill Inc., San Diego, USA) allows evaporative cooling by spraying an inert liquid coolant into the nasal cavity. The liquid evaporates instantaneously, thereby removing heat. The coolant is a proprietary perfluorochemical. Perflourochemicals are a family of chemicals that are both chemically and biologically non-reactive. These chemicals are among the least toxic compounds known. They cannot reach appreciable concentrations in tissues of air-exposed animals since they have limited ability to dissolve in biological media. They are highly volatile and have a high air–blood partition coefficient, which facilitates their rapid elimination through pulmonary expiration should any of it remain in the body after exposure (more information is available via 3M Specialty Materials. Robust summaries and test plan: perfluoro-compounds, C5–C18; revised summaries. EPA Report 201-14684B, Aug 2003). The cooling and safety profile associated with the specific perfluorochemical used in the coolant has been determined by Wolfson et al. in a sheep model,¹⁰ where no damage to the epithelial surface could be detected. The nasal cavity with its proximity to the cerebral circulation, basal brain regions and the brain stem offers an approach that might cause preferential brain cooling. The device has been tested in a pig model of prolonged ventricular fibrillation cardiac arrest during cardiopulmonary resuscitation (CPR). After 10 min of cardiac arrest, cooling and CPR were begun simultaneously. Jugular vein temperature, which was used as surrogate for brain temperature, dropped from 38.1 °C to 34.2 °C within 5 min of CPR.¹¹ Pigs and sheep however differ considerably to humans in their ratio between the size of their nasal cavity and their brain. We hypothesized that nasal evaporative cooling is safe and feasible in patients after cardiac arrest and successful resuscitation, and effective in inducing systemic mild therapeutic hypothermia.

Section snippets

Study design

The primary aim of this prospective, multi-center, single-arm observational study was to demonstrate safety, feasibility and cooling effectivity of nasopharyngeal evaporative cooling in comatose patients after successful resuscitation from cardiac arrest. Primary endpoints were cooling rate, time needed to achieve mild hypothermia (34 °C) and target temperature (33 °C), and the evaluation of possible side effects of evaporative cooling in the nasopharynx and elsewhere. The secondary endpoints

Patient characteristics

Between September 2007 and August 2008, 84 patients were enrolled. Age was 71 (63; 79) years, body mass index 26 (24; 29), 64 (76%) patients were male. None of the patients who regained consciousness denied consent or was lost to follow-up. Patient characteristics and resuscitation data are presented in Table 1.

Cooling effectivity

Cooling was initiated 90 (68; 125) min after collapse, 70 (41; 96) min after ROSC and 35 (17; 73) min after arrival in the emergency department. Duration of nasopharyngeal cooling was 60

Discussion

In this observational study the RhinoChill device effectively lowered tympanic and core temperatures in patients after cardiac arrest. The device proved feasible in an emergency department setting, and safe during 1 h use, with the exception of persistent tissue damage in 1 patient at the high oxygen flow rate of 60–80 L/min. At the lower oxygen flow rate of 40–50 L/min, no persistent cold-related tissue damage was observed. Importantly, this reduction in flow rate did not affect the cooling rate.

Conclusion

Nasopharyngeal cooling for 1 h using the RhinoChill device is effective in reducing core temperature in cardiac arrest survivors. The method device is safe at oxygen flow rates of 40–50 L/min. Clinical studies will have to confirm safety and feasibility of the device for more prolonged use.

Conflict of interest statement

BeneChill Inc. supported the participating centres with a per-patient-support used for medical supplies and personnel for data processing. This conflict of interest applies for all authors and co-authors. Dr. Andreas Janata received a travel grant and support for manuscript preparation from BeneChill Inc. Denise Barbut is co-founder of BeneChill Inc., intellectual property holder and stockholder. Becky Inderbitzen is an employee of BeneChill Inc.

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^☆: A Spanish translated version of the abstract of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2010.04.027.

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Clinical paperSafety and feasibility of nasopharyngeal evaporative cooling in the emergency department setting in survivors of cardiac arrest☆

Abstract

Aim

Methods

Results

Conclusions

Introduction

Section snippets

Study design

Patient characteristics

Cooling effectivity

Discussion

Conclusion

Conflict of interest statement

Ann Emerg Med

J Am Coll Cardiol

Resuscitation

Int J Cardiol

J Am Coll Cardiol

Ann Emerg Med

Resuscitation

Resuscitation

Resuscitation

Clinical paper
Safety and feasibility of nasopharyngeal evaporative cooling in the emergency department setting in survivors of cardiac arrest☆