Microsoft word - as cooling references summaries 8-3-06.rtf

1. Calver P, Braungardt T, Kupchik N, Jensen A, Cutler C. The big chill: improving the odds after cardiac arrest. RN 2005; 68:58-62. Review article written by nurses about the use of mild hypothermia for post cardiac arrest patients. They present a case study on a 53yr old man who they treated with mild hypothermia (33°C) for 24 hours. He woke up 36 hours later with no permanent brain damage and fully restored cardiac function. Some of the key clinical studies which support the use of hypothermia in such patients are reviewed. The Arctic Sun is described as a preferred alternative to their standard cooling blankets and is also pictured in the article. 2. Carhuapoma JR, Gupta K, Coplin WM, Muddassir SM, Meratee MM. Treatment of refractory fever in the neurosciences critical care unit using a novel, water-circulating cooling device: a single-center pilot experience. J Neurosurg Anesthesiol 2003; 15:313-318. This is a safety and efficacy study of the Arctic Sun used in 6 febrile acute brain injury patients. Each patient had a fever of greater than 38oC that was refractory to antipyretic pharmacological treatment. The target temperature was 36.5oC. The temperature response of the patients was analyzed for the first 600 minutes of treatment. The mean starting temperature for all patients was 38.4oC and at 120 minutes they had reached 36.9oC. All patients were controlled at the target temperature for the remainder of the treatment. 5 of the 6 patients developed shivering that was controlled by increased sedation (propofol) and supplemental low dose meperidine. No skin reactions were noted in any of the 6 patients. Carhuapoma, et al conclude that the Arctic Sun is safe, effective and able to maintain sustained normothermia following fever in a cohort of critically ill neurologic/neurosurgical patients. Medivance arctic sun temperature management system. Neurocrit Care 2005; 3:63-67. Geocadin and Carhuapoma describe the Arctic Sun temperature Management System in this article. The Arctic Sun is a non-invasive, thermal regulating system composed of a control module and disposable, non-sterile Energy Transfer Pads. They note that the Arctic Sun design is based on the principle of water immersion that is known to be the most efficient non-invasive method for hypothermia induction. The control module provides temperature controlled water to the Energy Transfer Pads. In automatic mode, a patient temperature probe provides a feedback signal that enables the control module to adjust water temperature to achieve a preset target temperature. Construction of the Energy Transfer pads is described and the early clinical experience with the system is summarized. Finally there is a discussion of the practical aspects of using the Arctic Sun, including the need to manage shivering. Clinically induced hypothermia: why chill your patient? AACN Adv Crit Care 2006; 17:125-132. Review article written by a nursing manager on therapeutic hypothermia for post cardiac arrest, which discusses the benefits and potential adverse effects of hypothermia, as well as the various methods. The Arctic Sun is included with a paragraph summary of how it differs from other surface methods. Nursing considerations in the management of hypothermic patients, including monitoring temperature and shivering control are discussed. 5. Ly HQ, Denault A, Dupuis J, Vadeboncoeur A, Harel F, Arsenault A, Gibson CM, Bonan R. A pilot study: The Noninvasive Surface Cooling Thermoregulatory System for Mild Hypothermia Induction in Acute Myocardial Infarction (The NICAMI Study). Am Heart J 2005; 150:933. Hypothermia has been shown to reduce metabolic demand, limit reperfusion injury and salvage the injured myocardium in STEMI. Ly, et al report a safety and efficacy study of the Arctic Sun for inducing hypothermia in ST-elevation myocardial infarction (STEMI) patients undergoing percutaneous coronary intervention (PCI). Hypothermia was initiated in the emergency department continued in the cath lab and was complete in the intensive care unit. Nine patients were successfully cooled with a mean time to target of 79 minutes. In the last four patients of the series, the time to target was 49 minutes. Cooling duration was 267 minutes. Shivering was controlled using meperidine and there were no adverse effects of hypothermia. Ly, et al conclude that mild hypothermia can induced with the Arctic Sun in patients with STEMI undergoing primary PCI allowing earlier myocardial protection before mechanical reperfusion therapy. 6. Mahmood MA, Voorhees ME, Parnell M, Zweifler RM. Transcranial Doppler ultrasonographic evaluation of middle cerebral artery hemodynamics during mild hypothermia. J Neuroimaging 2005; 15:336-340. The effect of mild hypothermia on cerebral hemodynamics is not well known. The authors investigated the influence of brain temperature on middle cerebral artery (MCA) mean flow velocity (MCA FV) and pulsatility index (MCA PI) in nonintubated, healthy volunteers undergoing mild induced hypothermia. Mild hypothermia (target tympanic membrane temperature 34.5oC) was induced in subjects using the Arctic Sun Temperature Management System. MCA FV and MCA PI were recorded bilaterally with a 2 MHz pulsed probe every 30 minutes via the transtemporal window. Eighteen subjects (8 males, 10 females) 32 +/- 8 years of age were studied. Multivariate analysis indicated that MCA FV increased with increasing change in temperature (P< .001), heart rate (HR) (P< .001), end-tidal CO 2(P= .025), arterial oxygen saturation (O2%) (P= .001), and with decreasing mean arterial blood pressure (P= .004). Multivariate analysis also indicated that ln(MCA PI) (natural logarithm of MCA PI) decreased with decreasing T tym(P< .001) and increasing HR (P< .001). Mild induced hypothermia is associated with an increase in MCA FV and a decrease in MCA PI. The increase in MCA FV may be partially due to microcirculatory vasodilation. 7. Mayer SA, Kowalski RG, Presciutti M, Ostapkovich ND, McGann E, Fitzsimmons BF, Yavagal DR, Du YE, Naidech AM, Janjua NA, Claassen J, Kreiter KT, Parra A, Commichau C. Clinical trial of a novel surface cooling system for fever control in neurocritical care patients. Crit Care Med 2004; 32:2508-2515. A comparative study to evaluate the effectiveness of the Arctic Sun (AS) versus conventional cooling blankets was conducted in 47 patients with fever (> 38.3°C for 2 consecutive hours after receiving 650mg of acetaminophen). This was a prospective trial in which mostly mechanically ventilated and sedated patients were randomized to either the Arctic Sun group or the cooling blanket group for 24 hours of treatment to attempt to achieve normothermia (37.2°C). Diagnoses of patients included subarachnoid hemorrhage (60%), cerebral infarction (23%), intracerebral hemorrhage (11%), and traumatic brain injury (4%). The groups were matched for baseline values; however, the mean patient temperature of the AS group was slightly higher than the blanket group. The AS group of 23 patients experienced a 75% reduction in fever burden (median 4.1 vs. 16.1°-hrs, p=.001). The Arctic Sun patients also spent less time febrile, more time normothermic, and attained normothermia faster than the blanket group. Shivering, once noted in either group,, was controlled by implementing via focal (hands and feet) and whole body forced air warming, and in some cases pharmacologic intervention (buspirone, meperidine, propofol, dexmedetomidine). Although in the AS group shivering occurred more frequently (39% vs. 8%, p=.013),it did not effect the ability of the product to rapidly bring a patient to normothermia. Shivering was managed in all patients in both groups in this study; however, shivering in patients being cooled can generally be avoided if treated for proactively, rather than to attempt to treat once after it begins. The authors conclude that the Arctic Sun system is superior to conventional cooling blanket therapy for controlling fever in critically ill neurologic patients. 8. Polderman KH, Rijnsburger ER, Peerdeman SM, Girbes AR. Induction of hypothermia in patients with various types of neurologic injury with use of large volumes of ice-cold intravenous fluid. Crit Care Med 2005; 33:2744-2751. Speed of induction is thought to be a key factor in hypothermia efficacy. In this prospective interventional study, the authors hypothesized that infusion of refrigerated fluids could be a safe accessory method to increase cooling speed. One hundred and thirty four (134) patients with various types of neurologic injury were included in the study. They were cooled by infusion of refrigerated fluids and the use of surface cooling devices. One of the surface cooling devices used was the Arctic Sun. An average volume of 2340 +/- 890 mL of refrigerated fluids was infused in 50 mins. Core temperatures decreased from 36.9 +/- 1.9 degrees C to 34.6 +/- 1.5 degrees C at t = 30 mins and to 32.9 +/- 0.9 degrees C at t = 60 mins (target temperature: 32 degrees C-33 degrees C). No patients developed pulmonary edema and there were no other adverse effects. The authors conclude that induction of hypothermia by means of cold-fluid infusion combined with surface cooling devices is safe, efficacious, and quick. Because the speed of cooling is important to increase its protective effects, they recommend that cold-fluid infusion be used in all patients treated with induced hypothermia. This should be combined with another method to safely and accurately maintain hypothermia once target temperatures have been reached. 9.Zweifler RM, Voorhees ME, Mahmood MA, Alday DD. Induction and maintenance of mild hypothermia by surface cooling in non-intubated subjects. J Stroke Cere Dis 2003; 12:237-243. This publication describes the initial use of the Arctic Sun Energy Transfer Pads and the Arctic Sun control module for induction of mild hypothermia. Ten non-intubated, healthy volunteers were cooled to 34.5oC for over 5 hours. Meperidine was used to suppress shivering. In Phase I, five volunteers were cooled using the Energy Transfer Pads with manual water control. In Phase II, five volunteers were cooled using the Energy Transfer Pads with the Arctic Sun control module. The cooling rate for all subjects was 1.4oC per hour and subjects were maintained at a stable target temperature. Zweifler, et al conclude that the Arctic Sun rapidly and comfortably induces mild hypothermia in unanesthetized, non-intubated humans. 10. Zweifler RM, Voorhees ME, Mahmood MA, Parnell M. Rectal Temperature Reflects Tympanic Temperature During Mild Induced Hypothermia in Nonintubated Subjects. J Neurosurg Anesthesiol 2004; 16:232-235. Dependable non-invasive measurements of brain temperature are necessary for the clinical application of mild hypothermia. Tympanic temperature correlates best with brain temperature but it is a cumbersome location to record from continuously in the clinical setting. The objective of this study was to determine the relationship between tympanic and rectal temperature. Mild hypothermia was induced in twenty-two volunteers with the Arctic Sun Temperature Management System. Subjects showed a triphasic temperature response: induction, maintenance, and rewarming. The mean gradient (Ttym-Trec) at baseline was -0.1 +/- 0.3 degrees C and the maximum gradient increased to -0.6 +/- 0.4 degrees C at 105 minutes. During maintenance of hypothermia (from 150 to 300 minutes), the mean gradient was -0.3 +/- 0.5 degrees C. The authors concluded that tympanic and rectal temperatures are not related during induction of hypothermia, but correlate during the maintenance of hypothermia. 11. Zweifler RM, Voorhees ME, Mahmood MA, Parnell M. Magnesium sulfate increases the rate of hypothermia via surface cooling and improves comfort. Stroke 2004; 35:2331-2334. The purpose of this study was to assess the hypothesis that the addition of intravenous MgSO4 to an antishivering pharmacological regimen increases the cooling rate when using a surface cooling technique. Twenty-two healthy volunteers were studied. Hypothermia was induced using a surface technique with a target tympanic temperature of 34.5 degrees C. Subjects received 1 of the following pharmacological regimens: (1) meperidine monotherapy (n=5); (2) meperidine plus buspirone, 30 to 60 mg PO administered at the time of initiation of cooling (n=4); (3) meperidine and ondansetron, 8 to 16 mg IV administered as an 8 mg bolus at the time of initiation of cooling with an optional second dose after 4 hours as needed for nausea (n=5); or (4) meperidine, ondansetron, and MgSO4, 4 to 6 g IV bolus followed by 1 to 3 g per hour infusion (n=8). Thermal comfort was evaluated with a 100-mm-long visual analog scale. More subjects who received MgSO4 were vasodilated during hypothermia induction (7 of 8 [88%] versus 4 of 14 [29%]; P=0.024). MgSO4 (coefficient -17.265; p=0.039), weight (1.838, 0.001), and the initial 2-hour meperidine dose (0.726, 0.003) were found to significantly impact the time to achieve tympanic temperature of 35 degrees C. Subjects who received MgSO4 had significantly higher mean comfort scores than those who did not (48+/-15 versus 38+/-12; P<0.001). The authors concluded that administration of intravenous MgSO4 increases the cooling rate and comfort when using a surface cooling technique.

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