Fever is an important determinant of prognosis following acute brain injury. Current non-pharmacologic techniques to reduce fever are limited and induce a shivering response. We investigated the safety and efficacy of a novel transnasal unidirectional high flow air device in reducing core body temperature in the neurocritical care unit (NCCU) setting.
This pilot study included seven consecutive patients in the NCCU who were febrile (> 37.5 °C) for > 24 h despite standard non-pharmacologic and first-line antipyretic agents. Medical grade high flow air was delivered transnasally using a standard continuous positive airway pressure machine with a positive pressure of 20 cmH2O for 2 h. Core esophageal and tympanic temperature were continuously monitored.
Mean age was 40 ± 14 yo, and 72% (5/7 patients) were men. Five patients had intracerebral or intraventricular hemorrhage, one subject had transverse myelitis, and the remaining patient had anoxic brain injury due to a cardiac arrest. After 2 h of cooling, core temperature was significantly lower than the baseline pre-cooling temperature (37.3 ± 0.5 °C vs. 38.4 ± 0.6 °C; p < 0.002). Mean transnasal airflow rate was 57.5 ± 6.5 liters per minute. Five of the seven subjects were normothermic at the end of the 2-h period. One subject with severe hyperthermia (39.7 °C) and the other with multiple interruptions to therapy due to technical reasons did not cool. The core temperature within 30 min of cessation of airflow increased and was similar to the pre-cooling baseline temperature (38.3 ± 0.4 °C vs. 38.4 ± 0.6 °C, p = NS). Rate of core cooling was 0.6 ± 0.15 °C per hour at this flow rate. No shivering response was observed. No protocol-related adverse events occurred.
High flow transnasal air in a unidirectional fashion lowers core body temperature in febrile patients in the NCCU setting. No adverse events were seen, and the process showed no signs of shivering or any other serious side effects during short-term exposure. This pilot study should inform further investigation.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
Tax calculation will be finalised during checkout.
Neurocritical care unit
Ear, nose and throat
Continuous positive airway pressure
Liters per minute
Systolic blood pressure
Diastolic blood pressure
Bohman L-E, Levine JM. Fever and therapeutic normothermia in severe brain injury: an update. Curr Opin Crit Care. 2014;20:182–8.
Madden LK, Hill M, May TL, Human T, Guanci MM, Jacobi J, Moreda MV, Badjatia N. The implementation of targeted temperature management: an evidence-based guideline from the Neurocritical Care Society. Neurocrit Care. 2017;27(3):468–87.
Fernandez A, Schmidt J, Claassen J, et al. Fever after subarachnoid hemorrhage risk factors and impact on outcome. Neurology. 2007;68:1013–9.
Ntaios G, Dziedzic T, Michel P, et al. European Stroke Organisation (ESO) guidelines for the management of temperature in patients with acute ischemic stroke. Int J Stroke. 2015;10:941–9.
Diringer MN. Treatment of fever in the neurologic intensive care unit with a catheter-based heat exchange system. Crit Care Med. 2004;32:559–64.
Diringer MN, Reaven NL, Funk SE, Uman GC. Elevated body temperature independently contributes to increased length of stay in neurologic intensive care unit patients. Crit Care Med. 2004;32:1489–95.
Scaravilli V, Tinchero G, Citerio G. Participants in the international multi-disciplinary consensus conference on the critical care management of subarachnoid H. Fever management in SAH. Neurocrit Care. 2011;15:287–94.
Polderman KH, Herold I. Therapeutic hypothermia and controlled normothermia in the intensive care unit: practical considerations, side effects, and cooling methods. Crit Care Med. 2009;37:1101–20.
Hoedemaekers CW, Ezzahti M, Gerritsen A, van der Hoeven JG. Comparison of cooling methods to induce and maintain normo- and hypothermia in intensive care unit patients: a prospective intervention study. Crit Care. 2007;11:R91.
Mayer SA, Kowalski RG, Presciutti M, et al. Clinical trial of a novel surface cooling system for fever control in neurocritical care patients. Crit Care Med. 2004;32:2508–15.
Badjatia N, Strongilis E, Gordon E, et al. Metabolic impact of shivering during therapeutic temperature modulation: the Bedside Shivering Assessment Scale. Stroke. 2008;39:3242–7.
Patel N, Nair SU, Gowd P, et al. Central line associated blood stream infection related to cooling catheter in cardiac arrest survivors undergoing therapeutic hypothermia by endovascular cooling. Conn Med. 2013;77:35–41.
Polderman KH, Callaghan J. Equipment review: cooling catheters to induce therapeutic hypothermia? Crit Care. 2006;10:234.
Chava R, Zviman M, Raghavan MS, et al. Rapid Induction of therapeutic hypothermia using transnasal high flow dry air. Ther Hypothermia Temp Manag. 2017;7:50–6.
Covaciu L, Allers M, Enblad P, Lunderquist A, Wieloch T, Rubertsson S. Intranasal selective brain cooling in pigs. Resuscitation. 2008;76:83–8.
Castren M, Nordberg P, Svensson L, et al. Intra-arrest transnasal evaporative cooling: a randomized, prehospital, multicenter study (PRINCE: Pre-ROSC IntraNasal Cooling Effectiveness). Circulation. 2010;122:729–36.
Song SS, Lyden PD. Overview of therapeutic hypothermia. Curr Treat Options Neurol. 2012;14:541–8.
Hinz J, Rosmus M, Popov A, Moerer O, Frerichs I, Quintel M. Effectiveness of an intravascular cooling method compared with a conventional cooling technique in neurologic patients. J Neurosurg Anesthesiol. 2007;19:130–5.
Flint AC, Hemphill JC, Bonovich DC. Therapeutic hypothermia after cardiac arrest: performance characteristics and safety of surface cooling with or without endovascular cooling. Neurocrit Care. 2007;7:109–18.
Lyden P, Ernstrom K, Cruz-Flores S, et al. Determinants of effective cooling during endovascular hypothermia. Neurocrit Care. 2012;16:413–20.
Badjatia N, Bodock M, Guanci M, et al. Rapid infusion of cold saline (4°) as adjunctive treatment of fever in patients with brain injury. Neurology. 2006;66:1739–41.
Choi HA, Ko SB, Presciutti M, et al. Prevention of shivering during therapeutic temperature modulation: the Columbia anti-shivering protocol. Neurocrit Care. 2011;14:389–94.
Einer-Jensen N, Khorooshi M. Cooling of the brain through oxygen flushing of the nasal cavities in intubated rats: an alternative model for treatment of brain injury. Exp Brain Res. 2000;130:244–7.
Mellergård P. Changes in human intracerebral temperature in response to different methods of brain cooling. Neurosurgery. 1992;31:671–7.
Harris B, Andrews P, Murray G. Enhanced upper respiratory tract airflow and head fanning reduce brain temperature in brain-injured, mechanically ventilated patients: a randomized, crossover, factorial trial. BJA Br J Anaesth. 2006;98:93–9.
Busch H-J, Eichwede F, Födisch M, et al. Safety and feasibility of nasopharyngeal evaporative cooling in the emergency department setting in survivors of cardiac arrest. Resuscitation. 2010;81:943–9.
Boller M, Lampe JW, Katz JM, Barbut D, Becker LB. Feasibility of intra-arrest hypothermia induction: a novel nasopharyngeal approach achieves preferential brain cooling. Resuscitation. 2010;81:1025–30.
Chava R, Zviman M, Assis FR, Raghavan MS, Halperin H, Maqbool F, Geocadin R, Quinones-Hinojosa A, Kolandaivelu A, Rosen BA, Tandri H. Effect of high flow transnasal dry air on core body temperature in intubated human subjects. Resuscitation. 2019;134:49–54.
Funding was provided by Key Technologies Inc.
Conflict of interest
Harikrishna Tandri is the founder of CoolTech Inc, which is developing a transnasal device for hypothermia. Other authors declare that they have no conflict of interest.
Ethical Approval/Informed Consent
This study was approved by the Johns Hopkins University Institutional Review Board (IRB00086134).
Human and Animal Rights
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Ziai, W.C., Shah, D., Assis, F.R. et al. Feasibility and Safety of Transnasal High Flow Air to Reduce Core Body Temperature in Febrile Neurocritical Care Patients: A Pilot Study. Neurocrit Care 31, 280–287 (2019). https://doi.org/10.1007/s12028-019-00702-x
- Neurocritical Care
- Transnasal evaporative cooling