Cooling Techniques for Hyperthermia Publications (557)


Cooling Techniques for Hyperthermia Publications

Acta Ophthalmol
Acta Ophthalmol 2016 Dec 21. Epub 2016 Dec 21.
Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.

To assess the effect of elevated core body temperature on temporal and spatial contrast sensitivity and retinal vessel diameters.
The study included 13 healthy volunteers aged 20-37 years. Core body temperature elevation (target +1. Read More

1°C) was induced by wrapping the participants in cling film, tinfoil and warming blankets. Subsequent cooling was achieved by undressing. Flicker sensitivity (critical flicker fusion frequency) was chosen to assess temporal resolution, while the Freiburg Vision Test was used to determine spatial contrast sensitivity at 1.5 cycles per degree. Scanning laser ophthalmoscopy was used to measure retinal trunk vessel diameters. Assessment was made at baseline, during hyperthermia and after cooling.
The induction of a mean increase in core body temperature of 1.02°C was associated with a 7.15-mmHg mean reduction in systolic blood pressure (p < 0.01), a 10.6-mmHg mean reduction in diastolic blood pressure (p < 0.01), a mean increase in pulse rate of 36.3 bpm (p < 0.0001), a 2.66% improvement in flicker sensitivity (CI95 1.37-3.94, p < 0.001), a 2.80% increase in retinal artery diameters (CI95 1.09-4.51, p < 0.01) and a 2.95% increase in retinal vein diameters (CI95 0.96-4.94, p < 0.01). There was no detectable effect of temperature on spatial contrast sensitivity. All ocular test parameters returned to baseline levels after cooling.
Increased core body temperature was accompanied by improved temporal visual resolution and retinal trunk vessel dilation. The results suggest that hyperthermia is associated with enhanced retinal function and increased retinal metabolism.

Int J Occup Saf Ergon
Int J Occup Saf Ergon 2016 Dec 20:1-30. Epub 2016 Dec 20.
a Centre for Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory , University of Brighton , UK.
Ther Hypothermia Temp Manag
Ther Hypothermia Temp Manag 2016 Dec 13. Epub 2016 Dec 13.
Department of Neurology, University of Missouri , Columbia, Missouri.

Fever increases mortality and morbidity and length of stay in neurocritically ill patients. Various methods are used in the neuroscience intensive care unit (NSICU) to control fever. Two such methods involve the Arctic Sun hydrogel wraps and the Gaymar cooling wraps. Read More

The purpose of our study was to compare these two methods in neurocritical care patients who had temperature >37.5°C for more than three consecutive hours and that was refractory to standard treatments. Data of patients requiring cooling wraps for treatment of hyperthermia at an NSICU at an academic, tertiary referral center were retrospectively reviewed. The average temperature before cooling was 38.5°C ± 0.38°C and 38.4°C ± 0.99°C for the Gaymar and Arctic Sun groups, respectively (p = 0.89). The Gaymar group took on average 16 ± 21.9 hours to reach goal temperature, whereas the Arctic Sun group took 2.22 ± 1.39 hours (p = 0.08). The average time outside of the target temperature was 57.0 ± 58.0 hours in the Gaymar group compared with 13.7 ± 17.1 hours in the Arctic Sun group (p = 0.04). Average duration of using the cooling wraps was similar between the two groups; 81.8% of patients had rebound hyperthermia in the Gaymar group compared with 20% in the Arctic Sun group (p = 0.0089). The Arctic Sun group had a nonsignificant increased incidence of shivering compared with the Gaymar group (40% vs. 18.18%, p = 0.36). We found that Arctic Sun surface cooling device was more efficient in attaining the target temperature, had less incidence of rebound hyperthermia, and was able to maintain normothermia better than Gaymar cooling wraps. The incidence of shivering tended to be more common in the Arctic Sun group.

Ann Emerg Med
Ann Emerg Med 2016 Nov 16. Epub 2016 Nov 16.
Korey Stringer Institute, University of Connecticut, Storrs, CT.

We investigated the efficacy of tarp-assisted cooling as a body cooling modality.
Participants exercised on a motorized treadmill in hot conditions (ambient temperature 39.5°C [103. Read More

1°F], SD 3.1°C [5.58°F]; relative humidity 38.1% [SD 6.7%]) until they reached exercise-induced hyperthermia. After exercise, participants were cooled with either partial immersion using a tarp-assisted cooling method (water temperature 9.20°C [48.56°F], SD 2.81°C [5.06°F]) or passive cooling in a climatic chamber.
There were no differences in exercise duration (mean difference=0.10 minutes; 95% CI -5.98 to 6.17 minutes or end exercise rectal temperature (mean difference=0.10°C [0.18°F]; 95% CI -0.05°C to 0.25°C [-0.09°F to 0.45°F] between tarp-assisted cooling (48.47 minutes [SD 8.27 minutes]; rectal temperature 39.73°C [103.51°F], SD 0.27°C [0.49°F]) and passive cooling (48.37 minutes [SD 7.10 minutes]; 39.63°C [103.33°F], SD 0.40°C [0.72°F]). Cooling time to rectal temperature 38.25°C (100.85°F) was significantly faster in tarp-assisted cooling (10.30 minutes [SD 1.33 minutes]) than passive cooling (42.78 [SD 5.87 minutes]). Cooling rates for tarp-assisted cooling and passive cooling were 0.17°C/min (0.31°F/min), SD 0.07°C/min (0.13°F/min) and 0.04°C/min (0.07°F/min), SD 0.01°C/min (0.02°F/min), respectively (mean difference=0.13°C [0.23°F]; 95% CI 0.09°C to 0.17°C [0.16°F to 0.31°F]. No sex differences were observed in tarp-assisted cooling rates (men 0.17°C/min [0.31°F/min], SD 0.07°C/min [0.13°F/min]; women 0.16°C/min [0.29°F/min], SD 0.07°C/min [0.13°F/min]; mean difference=0.02°C/min [0.04°F/min]; 95% CI -0.06°C/min to 0.10°C/min [-0.11°F/min to 0.18°F/min]). Women (0.04°C/min [0.07°F/min], SD 0.01°C/min [0.02°F/min]) had greater cooling rates than men (0.03°C/min [0.05°F/min], SD 0.01°C/min [0.02°F/min]) in passive cooling, with negligible clinical effect (mean difference=0.01°C/min [0.02°F/min]; 95% CI 0.001°C/min to 0.024°C/min [0.002°F/min to 0.04°F/min]). Body mass was moderately negatively correlated with the cooling rate in passive cooling (r=-0.580) but not in tarp-assisted cooling (r=-0.206).
In the absence of a stationary cooling method such as cold-water immersion, tarp-assisted cooling can serve as an alternative, field-expedient method to provide on-site cooling with a satisfactory cooling rate.

Iran Red Crescent Med J
Iran Red Crescent Med J 2016 Aug 5;18(8):e23827. Epub 2016 Jun 5.
Department of Pediatrics, Turgut Ozal University, Ankara, Turkey.
J Occup Environ Hyg
J Occup Environ Hyg 2017 Feb;14(2):124-134
a TRC Environmental , New York , New York.

Although many apheresis centers offer extracorporeal photopheresis (ECP), little is known about current treatment practices.
An electronic survey was distributed to assess ECP practice internationally.
Of 251 responses, 137 met criteria for analysis. Read More

Most respondents were from North America (80%). Nurses perform ECP at most centers (84%) and the majority of centers treat adults only (52%). Most centers treat fewer than 50 patients/year (83%) and perform fewer than 300 procedures/year (70%). Closed system devices (XTS and/or Cellex) are used to perform ECP at most centers (96%). The most common indications for ECP are acute/chronic skin graft versus host disease (89%) and cutaneous T-cell lymphoma (63%). The typical wait time for ECP treatment is less than 2 weeks (91%). Most centers do not routinely perform quality control assessment of the collected product (66%). There are device-specific differences in treatment parameters. For example, XTS users more frequently have a minimum weight limit (P = 0.003) and use laboratory parameters to determine eligibility for treatment (P = 0.03). Regardless of device used, the majority of centers assess the clinical status of the patient before each procedure. Greater than 50% of respondents would defer treatment for hemodynamic instability due to active sepsis or heart failure, positive blood culture in the past 24 h or current fever.
This survey based study describes current ECP practices. Further research to provide evidence for optimal standardization of patient qualifications, procedure parameters and product quality assessment is recommended.

Int J Hyperthermia
Int J Hyperthermia 2016 Nov 11;32(7):749-56. Epub 2016 Jul 11.
a Department of General, Visceral and Vascular Surgery , Charité - Campus Benjamin Franklin , Berlin ;

Major limitations of conventional RFA are vascular cooling effects. However, vascular cooling effects are supposed to be less pronounced in multipolar RFA. The objective of this ex vivo study was a systematic evaluation of the vascular cooling effects in multipolar RFA. Read More

Multipolar RFA with three bipolar RFA applicators was performed ex vivo in porcine liver (applicator distance 20 mm, energy input 40 kJ). A saline-perfused glass tube ('vessel') was placed parallel to the applicators in order to simulate a natural liver vessel. Five applicator-to-vessel geometries were tested. A liquid-filled glass tube without perfusion was used as a dry run. Ablations were orthogonally cut to the applicators at a defined height. Cooling effects were analysed qualitatively and quantitatively along these cross sectional areas.
Thirty-six ablations were performed. A cooling effect could be seen in all ablations with perfused vessels compared to the dry run. While this cooling effect did not have any influence on the ablation areas (859-1072 mm(2) versus 958 mm(2) in the dry run, p > 0.05), it had a distinctive impact on ablation shape. A vascular cooling effect could be observed in all ablations with perfusion directly around the vessel independent of the applicator position compared to the dry run (p < 0.01).
A vascular cooling effect occurred in all multipolar RFA with simulated liver vessels ex vivo independent of the applicator-to-vessel geometry. While the cooling effect did not influence the total ablation area, it had a distinctive impact on the ablation shape.

Expert Rev Med Devices
Expert Rev Med Devices 2016 May 15;13(5):423-33. Epub 2016 Apr 15.
d Department of Emergency Medicine, Advocate Christ Medical Center , University of Illinois , Chicago, Oak Lawn , IL , USA.

Managing core temperature is critical to patient outcomes in a wide range of clinical scenarios. Previous devices designed to perform temperature management required a trade-off between invasiveness and temperature modulation efficiency. The Esophageal Cooling Device, made by Advanced Cooling Therapy (Chicago, IL), was developed to optimize warming and cooling efficiency through an easy and low risk procedure that leverages heat transfer through convection and conduction. Read More

Clinical data from cardiac arrest, fever, and critical burn patients indicate that the Esophageal Cooling Device performs very well both in terms of temperature modulation (cooling rates of approximately 1.3°C/hour, warming of up to 0.5°C/hour) and maintaining temperature stability (variation around goal temperature ± 0.3°C). Physicians have reported that device performance is comparable to the performance of intravascular temperature management techniques and superior to the performance of surface devices, while avoiding the downsides associated with both.