- Research article
- Open Access
- Open Peer Review
Temperature modulation with an esophageal heat transfer device- a pediatric swine model study
© Kulstad et al.; licensee BioMed Central. 2015
- Received: 12 October 2014
- Accepted: 15 January 2015
- Published: 4 February 2015
An increasing number of conditions appear to benefit from control and modulation of temperature, but available techniques to control temperature often have limitations, particularly in smaller patients with high surface to mass ratios. We aimed to evaluate a new method of temperature modulation with an esophageal heat transfer device in a pediatric swine model, hypothesizing that clinically significant modulation in temperature (both increases and decreases of more than 1°C) would be possible.
Three female Yorkshire swine averaging 23 kg were anesthetized with inhalational isoflurane prior to placement of the esophageal device, which was powered by a commercially available heat exchanger. Swine temperature was measured rectally and cooling and warming were performed by selecting the appropriate external heat exchanger mode. Temperature was recorded over time in order to calculate rates of temperature change. Histopathology of esophageal tissue was performed after study completion.
Average swine baseline temperature was 38.3°C. Swine #1 exhibited a cooling rate of 3.5°C/hr; however, passive cooling may have contributed to this rate. External warming blankets maintained thermal equilibrium in swine #2 and #3, demonstrating maximum temperature decrease of 1.7°C/hr. Warming rates averaged 0.29°C/hr. Histopathologic analysis of esophageal tissue showed no adverse effects.
An esophageal heat transfer device successfully modulated the temperature in a pediatric swine model. This approach to temperature modulation may offer a useful new modality to control temperature in conditions warranting temperature management (such as maintenance of normothermia, induction of hypothermia, fever control, or malignant hyperthermia).
- Malignant Hyperthermia
- Hypoxic Ischemic Encephalopathy
- Patient Temperature
- Heat Transfer Device
- External Heat Exchanger
Modifying or influencing the temperature of patients has been shown to be important for a number of conditions. Temperature modulation includes reduction of body temperature below normal, maintenance of normal body temperature for the avoidance of febrile or hyperthermic states, and active warming of patients to avoid unintended reductions of body temperature. The strength of evidence for improved outcomes when temperature modulation is implemented in several clinical scenarios is such that it is now considered a standard of care, endorsed by major resuscitative, cardiovascular, neonatal, and/or surgical standards groups (including the American Heart Association, the International Liaison Committee on Resuscitation, the European Resuscitation Council, the National Institute of Child Health and Human Development, the National Institute for Health and Care Excellence, the Centers for Medicare and Medicaid Services via the Surgical Care Improvement Project, and the American Society of Anesthesiologists) [1–8]. In particular, adults who remain comatose after resuscitation from cardiac arrest, neonates suffering from hypoxic ischemic encephalopathy, and patients undergoing general surgical procedures longer than one hour in duration all have strong recommendations for temperature modulation. More broadly, temperature control has been shown either preliminarily, or potentially, to be beneficial for certain subsets of traumatic brain injury [9, 10], spinal cord injury [11–13], certain subsets of stroke [14–18], acute myocardial infarction [19–22], traumatic/hemorrhagic cardiac arrest , surgical operations lasting longer than one hour [24–29], hepatic encephalopathy [30–32], and sepsis/septic shock . The challenge of maintaining operative normothermia during procedures on patients with high surface to mass ratios, such as pediatric patients, is significant, and many approaches are being developed to address this need [34–36].
This prospective interventional study was performed by an experienced team under a protocol approved by the Institutional Animal Care and Use Committee (IACUC) of Loyola University Medical Center. The study utilized methods consistent with current veterinary and USDA standards, with a state-of-the-art, Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC) International-accredited vivarium. Animal care and handling was in accord with Office of Laboratory Animal Welfare guidance for humane care and use of animals and with regulations outlined in the USDA Animal Welfare Act (9 CFR Parts 1, 2 and 3) and the conditions specified in the Guide for the Care and Use of Laboratory Animals (National Academy Press, Washington DC, 1996). Animal experimentation was required to determine the in vivo feasibility of modulating temperature with this approach, as in vitro models can only roughly approximate human cardiovascular physiology. A swine model of the size chosen has similarity in size, physiology, and thoracic anatomy to pediatric patients.
Three female Yorkshire swine weighing 21 kg, 22.5 kg, and 24.6 kg, for a mean 22.7 kg ± 1.8 kg, were acclimated to the facility as part of an unrelated dermal study investigating a small (2 square centimeter) region of skin for a topical pharmaceutical. Animals were given 12 hours food restriction but free access to water before the intervention. Subjects were medicated with a pre-anesthetic mix of Telazol (tiletamine/zolazepam) 4.4 mg/kg and xylazine 2.0 mg/kg intramuscularly, endotracheally intubated and anesthetized with 3% inhalational isoflurane (with concentration adjusted as needed to maintain anesthesia). No paralytics were used during any part of the study. Normal saline was instilled at a maintenance rate (2 cc/kg/hr) via ear vein. Continuous cardiac monitoring was performed with a 3-lead EKG rhythm recorder.
The heat exchange device was connected to an external heat exchange unit (Gaymar Medi-Therm III, Gaymar industries, Inc., Orchard Park, New York) which uses distilled water as the coolant, and the unit was powered up. The tip of the device was lubricated with a water soluble lubricant and inserted through the oropharynx into the esophagus to a depth sufficient for the tip to rest in the stomach. Adequate placement was confirmed by auscultation of stomach sounds during insufflation of air via syringe, followed by withdrawal of stomach contents through the central gastric access pathway within the device. The heat exchange unit was operated in patient control mode, in which the Medi-Therm III machine automatically regulates the patient’s temperature to the selected set point. The machine constantly compares actual patient temperature with the set point value, and automatically adjusts the water temperature so that the desired patient temperature is achieved.
Although the first subject demonstrated a maximum temperature decrease of 3.5°C/hr, passive cooling theoretically may have contributed up to 1.8°C/hr of this rate. Likewise, due to passive losses in the cold laboratory environment, upon switching the chiller to warming mode at 83 minutes, additional decreases in temperature were seen (albeit at a much slower rate). In order to achieve full reversal of temperature decrease, the subject was covered at 155 minutes, and warm IV fluids were substituted for the room temperature fluids initially administered at 165 minutes into the protocol. These measures were sufficient to counteract the ongoing passive heat losses and resulted in a demonstrable increase in temperature (at a rate of 0.34°C/hr). Finally, at 243 minutes into the protocol, an external heated water blanket was applied and set to 39°C, resulting in further increase in the rate of temperature gain (to a rate of 0.95°C/hr).
Histopathology of the esophagus of all three animals, performed after necropsy by a certified veterinary pathologist immediately after device removal using standard microscopic evaluation of thin sections of tissues, revealed normal tissue without evidence of injury.
Although a variety of approaches currently exist for controlling a patient’s temperature, many have inherent limitations. Surface devices are cumbersome, uncomfortable to surrounding operative staff, and of limited effectiveness when removed to gain access for surgical procedures. Intravascular catheters require sterile placement into the vasculature and the consequent risk of blood clots or infections. Controlling a patient’s temperature through the gastrointestinal tract has been accomplished with varying degrees of efficacy, both for cooling [39–42] and for warming [43–46] using various techniques and approaches. Using a free installation of liquid (water, or normal saline) that is either cooled with ice or warmed as appropriate for the intended effect has been the most common method of temperature control through the gastrointestinal tract, and is utilized as a mechanism of inducing therapeutic hypothermia in various hospitals [47, 48]. Warming efforts in the past have been less successful , and interest in this approach to temperature management specifically for warming appears to have diminished after publication of a letter which our research group recently found to contain an incorrect mathematical analysis . In the device evaluated in this report, liquid is contained in a closed circuit system, avoiding the risks and potential complications of instilling free liquid into the gastrointestinal system. Additionally, the device tested in this investigation likely leverages more advanced materials, design specifications, and tolerances than were available in earlier investigations, allowing for greater performance and efficiency than has been achieved in earlier attempts to induce temperature change through the gastrointestinal tract.
We encountered greater ambient heat loss than initially expected. Cold laboratory conditions, combined with the small size of the swine, caused an unexpectedly high rate of heat loss, prompting the use of passive (blankets) as well as active (warmed IV fluids) warming methods to compensate. This permitted a more accurate determination of the cooling capability of the device, but limits the ability to make definitive conclusions regarding the maximum potential warming rates. It is likely that this device alone would not be sufficient to counter the threat of perioperative hypothermia in the most extreme cases (prolonged surgeries with extensive thoraco-abdominal exposure, for example); however, this esophageal heat transfer approach may be useful as an adjunct to these cases, and in less intense heat-loss situations, may be sufficient as the sole modality to avoid inadvertent perioperative hypothermia.
Placement of a device into the esophagus for the purpose of controlling patient temperature is more invasive than the use of external surface heat transfer devices; however, as compared with intravascular catheter devices used for this purpose, an esophageal approach can be considered less invasive. Additionally, an esophageal device requires no sterility for placement, and many patients undergoing temperature management, such as in the intensive care unit or operating room, receive a standard nasogastric or orogastric tube anyway.
Limitations of this investigation include the small sample size utilized. Although a larger sample would provide more refined data, the current data generally support the hypothesis that clinically significant modulations in temperature are possible in a pediatric model, and suggest that this may hold true in pediatric patients as well. Isoflurane may have contributed to systemic vasodilation and consequent increase in heat loss to the environment, particularly at the upper ranges of concentration utilized. We only measured temperature rectally, and rectal temperatures are known to lag those obtained from either bladder or intravascular means. Nevertheless, the expected differences in rates of temperature change are unlikely to affect our overall conclusions on the ability of this approach to have the intended effect on body temperature.
In conclusion, we found that an esophageal heat transfer device successfully modulated the temperature of a pediatric swine model. This approach to temperature modulation may offer a useful new modality to control temperature in conditions warranting temperature management, such as maintenance of normothermia during surgery, induction of hypothermia for a growing number of indications (cardiac arrest, hypoxic ischemic encephalopathy, traumatic brain or spinal cord injury, stroke, etc.), fever control, or in the treatment of malignant hyperthermia.
Supported in part by a grant from the National Science Foundation (IIP-1142664). The esophageal device was provided by Advanced Cooling Therapy. Funding organizations were not involved in design, collection, analysis, and interpretation of data; in the writing of the manuscript; or in the decision to submit the manuscript for publication. Abstracts of this work were presented at the Society of Critical Care Medicine 42nd Critical Care Congress, held in San Juan, Puerto Rico, January 19-23, 2013, and the Illinois College of Emergency Physicians Spring Symposium held in Chicago, Illinois, May 2, 2013.
- Higgins RD, Raju TN, Perlman J, Azzopardi DV, Blackmon LR, Clark RH, et al.: Hypothermia and perinatal asphyxia: executive summary of the National Institute of Child Health and Human Development workshop.J Pediatr 2006,148(2):170–5. 10.1016/j.jpeds.2005.12.009View ArticlePubMedGoogle Scholar
- Blackmon LR, Stark AR: Hypothermia: a neuroprotective therapy for neonatal hypoxic-ischemic encephalopathy.Pediatrics 2006,117(3):942–8. 10.1542/peds.2005-2950View ArticlePubMedGoogle Scholar
- Field JM, Hazinski MF, Sayre MR, Chameides L, Schexnayder SM, Hemphill R, et al.: Part 1: executive summary: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.Circulation 2010,122(18 Suppl 3):S640–56.View ArticlePubMedGoogle Scholar
- Roehr CC, Hansmann G, Hoehn T, Buhrer C: The 2010 Guidelines on Neonatal Resuscitation (AHA, ERC, ILCOR): similarities and differences–what progress has been made since 2005?Klin Padiatr 2011,223(5):299–307. 10.1055/s-0031-1280750View ArticlePubMedGoogle Scholar
- Peberdy MA, Callaway CW, Neumar RW, Geocadin RG, Zimmerman JL, Donnino M, et al.: Part 9: post-cardiac arrest care: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.Circulation 2010,122(18 Suppl 3):S768–86.View ArticlePubMedGoogle Scholar
- Nolan JP, Neumar RW, Adrie C, Aibiki M, Berg RA, Bottiger BW, et al.: Post-cardiac arrest syndrome: Epidemiology, pathophysiology, treatment, and prognostication A Scientific Statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke.Resuscitation 2008,79(3):350–79. 10.1016/j.resuscitation.2008.09.017View ArticlePubMedGoogle Scholar
- Deakin CD, Morrison LJ, Morley PT, Callaway CW, Kerber RE, Kronick SL, et al.: International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations.Resuscitation 2010,2010(81 Suppl 1):e93–174.View ArticleGoogle Scholar
- Nolan JP, Morley PT, Hoek TL, Hickey RW: Therapeutic hypothermia after cardiac arrest. An advisory statement by the Advancement Life support Task Force of the International Liaison committee on Resuscitation.Resuscitation 2003,57(3):231–5. 10.1016/S0300-9572(03)00184-9View ArticlePubMedGoogle Scholar
- Crossley S, Reid J, McLatchie R, Hayton J, Clark C, MacDougall M, et al.: A systematic review of therapeutic hypothermia for adult patients following traumatic brain injury.Crit Care 2014,18(2):R75. 10.1186/cc13835View ArticlePubMedPubMed CentralGoogle Scholar
- Andrews PJ, Sinclair LH, Harris B, Baldwin MJ, Battison CG, Rhodes JK, et al.: Study of therapeutic hypothermia (32 to 35 degrees C) for intracranial pressure reduction after traumatic brain injury (the Eurotherm3235Trial): outcome of the pilot phase of the trial.Trials 2013,14(1):277. 10.1186/1745-6215-14-277View ArticlePubMedPubMed CentralGoogle Scholar
- Ahmad FU, Wang MY, Levi AD: Hypothermia for acute spinal cord injury–a review.World Neurosurg 2014,82(1–2):207–14.View ArticlePubMedGoogle Scholar
- Dietrich WD, Levi AD, Wang M, Green BA: Hypothermic treatment for acute spinal cord injury.Neurotherapeutics 2011,8(2):229–39. 10.1007/s13311-011-0035-3View ArticlePubMedPubMed CentralGoogle Scholar
- Dididze M, Green BA, Dalton Dietrich W, Vanni S, Wang MY, Levi AD: Systemic hypothermia in acute cervical spinal cord injury: a case-controlled study.Spinal Cord 2013,51(5):395–400. 10.1038/sc.2012.161View ArticlePubMedGoogle Scholar
- Polderman KH: Induced hypothermia and fever control for prevention and treatment of neurological injuries.Lancet 2008,371(9628):1955–69. 10.1016/S0140-6736(08)60837-5View ArticlePubMedGoogle Scholar
- Piironen K, Tiainen M, Mustanoja S, Kaukonen KM, Meretoja A, Tatlisumak T, et al.: Mild hypothermia after intravenous thrombolysis in patients with acute stroke: a randomized controlled trial.Stroke 2014,45(2):486–91. 10.1161/STROKEAHA.113.003180View ArticlePubMedGoogle Scholar
- Murtha LA, McLeod DD, McCann SK, Pepperall D, Chung S, Levi CR, et al.: Short-duration hypothermia after ischemic stroke prevents delayed intracranial pressure rise.Int J Stroke 2014,9(5):553–9. 10.1111/ijs.12181View ArticlePubMedGoogle Scholar
- Hong JM, Lee JS, Song HJ, Jeong HS, Choi HA, Lee K: Therapeutic hypothermia after recanalization in patients with acute ischemic stroke.Stroke 2014,45(1):134–40. 10.1161/STROKEAHA.113.003143View ArticlePubMedGoogle Scholar
- Guluma KZ, Hemmen TM, Olsen SE, Rapp KS, Lyden PD: A trial of therapeutic hypothermia via endovascular approach in awake patients with acute ischemic stroke: methodology.Acad Emerg Med 2006,13(8):820–7. 10.1111/j.1553-2712.2006.tb01731.xView ArticlePubMedGoogle Scholar
- Erlinge D, Gotberg M, Lang I, Holzer M, Noc M, Clemmensen P, et al.: Rapid endovascular catheter core cooling combined with cold saline as an adjunct to percutaneous coronary intervention for the treatment of acute myocardial infarction. The CHILL-MI trial: a randomized controlled study of the use of central venous catheter core cooling combined with cold saline as an adjunct to percutaneous coronary intervention for the treatment of acute myocardial infarction.J Am Coll Cardiol 2014,63(18):1857–65. 10.1016/j.jacc.2013.12.027View ArticlePubMedGoogle Scholar
- Schwartz BG, Kloner RA, Thomas JL, Bui Q, Mayeda GS, Burstein S, et al.: Therapeutic hypothermia for acute myocardial infarction and cardiac arrest.Am J Cardiol 2012,110(3):461–6. 10.1016/j.amjcard.2012.03.048View ArticlePubMedGoogle Scholar
- Mottillo S, Sharma K, Eisenberg MJ: Therapeutic hypothermia in acute myocardial infarction: a systematic review.Can J Cardiol 2011,27(5):555–61. 10.1016/j.cjca.2010.12.027View ArticlePubMedGoogle Scholar
- Gotberg M, Olivecrona GK, Koul S, Carlsson M, Engblom H, Ugander M, et al.: A pilot study of rapid cooling by cold saline and endovascular cooling before reperfusion in patients with ST-elevation myocardial infarction.Circ Cardiovasc Interv 2010,3(5):400–7. 10.1161/CIRCINTERVENTIONS.110.957902View ArticlePubMedGoogle Scholar
- Tisherman SA: Salvage techniques in traumatic cardiac arrest: thoracotomy, extracorporeal life support, and therapeutic hypothermia.Curr Opin Crit Care 2013,19(6):594–8.PubMedGoogle Scholar
- Ruiz Tovar J, Badia JM: Prevention of surgical site infection in abdominal surgery. A critical review of the evidence.Cir Esp 2014,92(4):223–31. 10.1016/j.ciresp.2013.08.003View ArticlePubMedGoogle Scholar
- Steelman VM, Perkhounkova YS, Lemke JH: The Gap between Compliance with the Quality Performance Measure “Perioperative Temperature Management” and Normothermia.J Healthc Qual 2014. doi: 10.1111/jhq.12063. [Epub ahead of print]Google Scholar
- Tran AH, Kiamanesh F, Maga JM, Blitz A, Salgado CJ: Use of an intravascular warming catheter to maintain normothermia during flap reconstruction of the sternum.J Clin Anesth 2012,24(5):430–1. 10.1016/j.jclinane.2011.07.010View ArticlePubMedGoogle Scholar
- Carpenter L, Baysinger CL: Maintaining perioperative normothermia in the patient undergoing cesarean delivery.Obstet Gynecol Surv 2012,67(7):436–46. 10.1097/OGX.0b013e3182605ccdView ArticlePubMedGoogle Scholar
- Mahoney CB, Odom J: Maintaining intraoperative normothermia: a meta-analysis of outcomes with costs.AANA J 1999,67(2):155–63.PubMedGoogle Scholar
- Rajagopalan S, Mascha E, Na J, Sessler DI: The effects of mild perioperative hypothermia on blood loss and transfusion requirement.Anesthesiology 2008,108(1):71–7. 10.1097/01.anes.0000296719.73450.52View ArticlePubMedGoogle Scholar
- Mohsenin V: Assessment and management of cerebral edema and intracranial hypertension in acute liver failure.J Crit Care 2013,28(5):783–91. 10.1016/j.jcrc.2013.04.002View ArticlePubMedGoogle Scholar
- Mpabanzi L, Jalan R: Neurological complications of acute liver failure: pathophysiological basis of current management and emerging therapies.Neurochem Int 2012,60(7):736–42. 10.1016/j.neuint.2011.10.014View ArticlePubMedGoogle Scholar
- Stravitz RT, Larsen FS: Therapeutic hypothermia for acute liver failure.Crit Care Med 2009,37(7 Suppl):S258. -264-S258–264View ArticlePubMedGoogle Scholar
- Young PJ, Bellomo R: Fever in sepsis: is it cool to be hot?Crit Care 2014,18(1):109. 10.1186/cc13726View ArticlePubMedPubMed CentralGoogle Scholar
- Perl T, Peichl LH, Reyntjens K, Deblaere I, Zaballos JM, Brauer A: Efficacy of a novel prewarming system in the prevention of perioperative hypothermia. A prospective, randomized, multicenter study.Minerva Anestesiol 2014,80(4):436–43.PubMedGoogle Scholar
- Lin EP, Smith K, Valley RD: Wet forced-air warming blankets are ineffective at maintaining normothermia.Paediatr Anaesth 2008,18(7):642–4. 10.1111/j.1460-9592.2008.02556.xView ArticlePubMedGoogle Scholar
- Kim P, Taghon T, Fetzer M, Tobias JD: Perioperative hypothermia in the pediatric population: a quality improvement project.Am J Med Qual 2013,28(5):400–6. 10.1177/1062860612473350View ArticlePubMedGoogle Scholar
- Vaicys V, Eason A, Schieber JD, Kulstad EB: Therapeutic hypothermia induction via an esophageal route–a computer simulation.Am J Emerg Med 2012,30(6):932–5. 10.1016/j.ajem.2011.04.026View ArticlePubMedGoogle Scholar
- Kulstad E, Metzger AK, Courtney DM, Rees J, Shanley P, Matsuura T, et al.: Induction, maintenance, and reversal of therapeutic hypothermia with an esophageal heat transfer device.Resuscitation 2013,84(11):1619–24. 10.1016/j.resuscitation.2013.06.019View ArticlePubMedGoogle Scholar
- Khalil HH, Mackeith RC: A simple method of raising and lowering body temperature.Br Med J 1954,2(4890):734–6. 10.1136/bmj.2.4890.734View ArticlePubMedPubMed CentralGoogle Scholar
- Barnard CN: Hypothermia; a method of intragastric cooling.Br J Surg 1956,44(185):296–8. 10.1002/bjs.18004418512View ArticlePubMedGoogle Scholar
- Wangensteen OH, Salmon PA, Griffen WO, Paterson JR, Fattah F: Studies of local gastric cooling as related to peptic ulcer.Ann Surg 1959, 150:346–60. 10.1097/00000658-195909000-00003View ArticlePubMedPubMed CentralGoogle Scholar
- Dunn JE, Williams LF: Esophageal Cooling as a Technic of Selective Brain Hypothermia. Techn Docum Rep Sam-Tdr-63–19.Tech Doc Rep U S Air Force Syst Command Electron Syst Div 1963, 94:1–7.PubMedGoogle Scholar
- Kristensen G, Gravesen H, Jordening H: Internal rewarming in hypothermia using a specially constructed gastro-oesophageal tube. A non-invasive method.Acta Anaesthesiol Belg 1984, 35 Suppl:175–7.PubMedGoogle Scholar
- Kristensen G, Gravesen H, Benveniste D, Jordening H: An oesophageal thermal tube for rewarming in hypothermia.Acta Anaesthesiol Scand 1985,29(8):846–8. 10.1111/j.1399-6576.1985.tb02308.xView ArticlePubMedGoogle Scholar
- Steib A, Beller JP, von Bandel M, Beck F, Chabrol JL, Otteni JC: Oesophageal thermal tube for intraoperative hypothermia in liver transplantation.Acta Anaesthesiol Scand 1993,37(2):199–202. 10.1111/j.1399-6576.1993.tb03701.xView ArticlePubMedGoogle Scholar
- Rasmussen YH, Leikersfeldt G, Drenck NE: Forced-air surface warming versus oesophageal heat exchanger in the prevention of peroperative hypothermia.Acta Anaesthesiol Scand 1998,42(3):348–52. 10.1111/j.1399-6576.1998.tb04928.xView ArticlePubMedGoogle Scholar
- Knapik P, Rychlik W, Siedy J, Nadziakiewicz P, Ciesla D: Comparison of intravascular and conventional hypothermia after cardiac arrest.Kardiol Pol 2011,69(11):1157–63.PubMedGoogle Scholar
- Kory P, Weiner J, Mathew JP, Fukunaga M, Palmero V, Singh B, et al.: A rapid, safe, and low-cost technique for the induction of mild therapeutic hypothermia in post-cardiac arrest patients.Resuscitation 2011,82(1):15–20. 10.1016/j.resuscitation.2010.08.020View ArticlePubMedGoogle Scholar
- Bräuer A, Weyland W: Oesophageal heat exchanger in the prevention of perioperative hypothermia.Acta Anaesthesiol Scand 1998,42(10):1232–3.View ArticlePubMedGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2253/15/16/prepub
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.