A human thermoregulation simulator for calibrating water-perfused cooling pad systems for therapeutic hypothermia

Priya S.E. Chacko, Ali Seifi, Kenneth R. Diller

Research output: Contribution to journalArticle

Abstract

The induction of a mild reduction in body core temperature has been demonstrated to provide neuroprotection for patients who have suffered a medical event resulting in ischemia to the brain or vital organs. Temperatures in the range of 32-34 °C provide the required level of protection and can be produced and maintained by diverse means for periods of days. Rewarming from hypothermia must be conducted slowly to avoid serious adverse consequences and usually is performed under control of the thermal therapeutic device based on a closed-loop feedback strategy based on the patient's core temperature. Given the sensitivity and criticality of this process, it is important that the device control system be able to interact with the human thermoregulation system, which itself is highly nonlinear. The therapeutic hypothermia device must be calibrated periodically to ensure that its performance is accurate and safe for the patient. In general, calibration processes are conducted with the hypothermia device operating on a passive thermal mass that behaves much differently than a living human. This project has developed and demonstrated an active human thermoregulation simulator (HTRS) that embodies major governing thermal functions such as central metabolism, tissue conduction, and convective transport between the core and the skin surface via the flow of blood and that replicates primary dimensions of the torso. When operated at physiological values for metabolism and cardiac output, the temperature gradients created across the body layers and the heat exchange with both an air environment and a clinical water-circulating cooling pad system match that which would occur in a living body. Approximately two-thirds of the heat flow between the core and surface is via convection rather than conduction, highlighting the importance of including the contribution of blood circulation to human thermoregulation in a device designed to calibrate the functioning of a therapeutic hypothermia system. The thermoregulation simulator functions as anticipated for a typical living patient during both body cooling and warming processes. This human thermoregulatory surrogate can be used to calibrate the thermal function of water-perfused cooling pads for a hypothermic temperature management system during both static and transient operation.

Original languageEnglish (US)
Article number034506
JournalJournal of Medical Devices, Transactions of the ASME
Volume11
Issue number3
DOIs
StatePublished - Sep 1 2017

Fingerprint

Hypothermia
Induced Hypothermia
Body Temperature Regulation
Cooling water
Hot Temperature
Simulators
Water
Equipment and Supplies
Temperature
Metabolism
Cooling
Hemodynamics
Rewarming
Torso
Convection
Blood Circulation
Thermal gradients
Brain Ischemia
Body Temperature
Brain

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Biomedical Engineering

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A human thermoregulation simulator for calibrating water-perfused cooling pad systems for therapeutic hypothermia. / Chacko, Priya S.E.; Seifi, Ali; Diller, Kenneth R.

In: Journal of Medical Devices, Transactions of the ASME, Vol. 11, No. 3, 034506, 01.09.2017.

Research output: Contribution to journalArticle

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