Efficacy of an Infrared Radiator for Hypothermia Prevention in a Simulated Setup of Entrapped Vehicle Accident Victims.

BACKGROUND: Prolonged extrication of entrapped patients after road traffic accidents increases the risk of sustained hypothermia. Accident-related hypothermia increases mortality in severely injured patients, and prehospital efforts to prevent hypothermia are essential. We evaluated various warming measures regarding their preclinical suitability and efficacy for patient warming, tested in realistically-simulated road traffic accident scenarios under cold ambient conditions in a climate chamber. METHODS: The effects of a chemical warming blanket (CWB), forced-air warming (FAW) device, or infrared radiator (IRR) on the core body and skin surface temperature of a subject previously exposed to a cold environment (5°C for 12 minutes) was recorded via temperature sensors and thermographically, respectively. Physiological parameters such as oxygen saturation, blood pressure, and heart rate were also monitored. RESULTS: Under cold environmental conditions, all devices were able to compensate or overcompensate the cooling of body parts directly exposed to the heating measure. In the body areas that were not directly warmed (back, lower extremities), only the CWB limited further cooling. FAW and IR irradiation rapidly and effectively warmed the heat-exposed areas (head and arms). However, both methods - but especially the IRR - led to a noticeably accelerated cooling in body parts not directly exposed to heat (back, legs). CONCLUSION: The increased mortality associated with hypothermia in severely injured crash victims during prolonged vehicle extrication has intensified efforts to prevent sustained hypothermia. The use of a CWB, FAW or IRR are in principle all suitable for reducing or compensating for heat loss. The ongoing cooling of those body parts not directly exposed to the heat source was interpreted as a steal phenomenon in regional blood flow. However, the practicality and effectiveness of these measures, combined with their logistical requirements, must be evaluated in real extrication scenarios.

Incidence and strategies for preventing sustained hypothermia of crash victims during prolonged vehicle extrication.

BACKGROUND: Vehicle extrication of crash victims is a highly-demanding challenge, due to the frequently life-threatening injuries of entrapped occupants. In this phase, crash victims are often exposed to the outdoor-temperature, with the risk of sustained hypothermia. Hypothermia can significantly raise the morbidity and mortality rates of crash victims. Therefore, we have correlated the incidence of severe car accidents with entrapped patients, the outdoor conditions, and expenditure of time for extrication. Furthermore, different warming strategies have been evaluated regarding their integrability within the rescue procedure. METHODS: To estimate the incidence of severe car accidents with entrapped patients, we performed retrospective data mining for the cold season of a three-year period in a rural district in Germany. We evaluated the integrability of a chemical heated blanket, its combined application with a forced-air warmer, or with an infrared radiator for patient warming. Therefore, we analysed the time tracking of extrication reference points during extrication exercises undertaken by the rescue services, simulating a severe vehicle accident and evaluated questionnaires administered to rescue personnel and subjects. Furthermore, we monitored subjects' physiologic parameters to estimate the warming effect. RESULTS: Incidence analysis resulted in extrication times of up to 80 min, representing two severely-entrapped patients per month in the cold seasons, corresponding to about four entrapments per 100.000 inhabitants every year. Of the different warming strategies analysed, the chemical blanket and the combination infrared radiator/chemical blanket were favoured regarding the items 'operator convenience', 'weight/size/handling', 'stability in positioning', 'time needed for installation', 'manpower requirement', 'hindrance during extrication operation', 'versality during extrication process', and 'robustness' by the rescue personnel; the forced-air warmer and the infrared radiator were preferred with regard to 'warming effect', the forced-air warmer and the chemical blanket was advantageous with regard to 'physical protection'. CONCLUSIONS: Vehicle extrication procedures are time consuming, a relevant finding that provides a rationale for discussing and optimising the rescue procedure to prevent sustained hypothermia. We determined that combined application of an infrared radiator and a chemical blanket is advantageous in terms of integration into the rescue process. However, a more detailed investigation, focussing on warming efficacy, must be performed.

Lubeluzole following traumatic brain injury in the rat.

Lubeluzole, a novel nitric oxide synthase (NOS) pathway modulator, was shown to be neuroprotective in cerebral ischemia as studied in animal models and clinical trials. The present study investigated the effect of lubeluzole on contusion volume and brain edema following traumatic brain injury. Sprague-Dawley rats (n = 36) were subjected to cortical impact injury. Lubeluzole (0.8 mg/kg i.v.; n = 18) or a corresponding volume of vehicle (n = 18) was injected 15 and 75 minutes following trauma. Animals were sacrificed 24 hours following trauma. Contusion volume was measured planimetrically from coronal slices stained with hematoxylin and eosin. In this group, T2-weighted magnetic resonance imaging (MRI) was also performed 90 minutes and 6 and 24 hours after trauma. Hemispheric swelling and water content were determined gravimetrically 24 hours after trauma. In this group, intracranial pressure (ICP), mean arterial blood pressure (MABP), and cerebral perfusion pressure (CPP) were monitored for 30 minutes before sacrifice. Lubeluzole did not reduce contusion volume, hemispheric swelling, or water content. ICP, MABP, and the resulting CPP did not differ between treated and untreated rats 24 hours after injury. T2-weighted MRI revealed a higher volume of edema at 90 minutes after trauma in treated rats. However, at 6 and 24 hours after trauma, no significant difference was discernible. Under these experimental conditions, lubeluzole fails to exert beneficial effects following experimental traumatic brain injury (TBI).

Magnetic resonance imaging studies with cluster algorithm for characterization of brain edema after controlled cortical impact injury (CCII).

Objective of this study was the characterization of traumatic brain injury induced by a "Controlled Cortical Impact" with magnetic resonance imaging techniques. The impact was applied to the intact dura of the left hemisphere in Sprague-Dawley rats. The pneumatic impactor was accelerated to a velocity of 7 m/s contusing the left temporo-parietal hemisphere to a depth of 2 mm. Posttraumatic hemispheric swelling and water content were determined gravimetrically, Evans Blue extravasation photometrically, and volume of ischemia by TTC-staining and planimetry. Magnetic resonance imaging was performed by a Bruker biospec 24/40, 90 min, 24 and 72 h post trauma using a T2w RARE sequence, a T1w sequence, before and after application of contrast agent, and a set of diffusion weighted images for calculation of ADC-maps. Data analysis was performed using a cluster algorithm enabling to interpret corresponding image pairs simultaneously. T2w imaging indicates the maximum edema about 24 h post trauma. Blood-brain barrier damage, detected by T1w imaging, is more predominant in the early posttraumatic phase. The cluster algorithm detects different edema components: from the necrotic core to the perifocal vasogenic rim. MRI in combination with the cluster algorithm will hopefully be a valuable tool in testing neuroprotective agents.

Characterisation of brain edema following "controlled cortical impact injury" in rats.

Significance, origin and nature of posttraumatic brain edema are still being debated. Recently, a "controlled cortical impact injury" (CCII) was introduced to model traumatic brain injury. Purpose of this study was to investigate the development and nature of brain edema following CCII. Traumatic brain injury was applied to the intact dura of the left hemisphere in Sprague-Dawley rats (n = 52, 250-350 g b.w.). Ketamine/xylazine-anesthesia or inhalation-anesthesia were used. A pneumatic impactor with a diameter of 5 mm contused the temporo-parietal cortex with a velocity of 7 m/s and an impact depth of 2 mm. 24 hours post injury the brains were removed. Posttraumatic hemispheric swelling and water content were determined gravimetrically, Evans blue extravasation spectrophotometrically, area and volume of ischemia by staining with TTC. MRI studies were performed with T1-,T2- and diffusion-weighted sequences. Posttraumatic swelling following CCII was 14.3 +/- 3.1%. Brain water content increased to 82.5 +/- 0.5% in lesioned hemisphere compared to 79.9 +/- 0.2% in control hemisphere. Following TTC staining, the average ischemic tissue volume was 56.7 +/- 19.2 mm3. There was a moderate uptake of Evans blue into the lesioned hemisphere. MRI studies demonstrated edema in 35.4 +/- 9.5 mm3 of the lesioned hemisphere. Gd-DTPA was taken up early after trauma only. A significantly decreased ADC (apparent diffusion coefficient) indicates the cytotoxic (ischemic) component of edema in this model. In conclusion, CCII produces significant posttraumatic brain swelling and edema which is both, of vasogenic and cytotoxic nature. Thus, the CCII models the human cortical contusion more appropriately and opens new avenues for therapeutical studies focussing on cortical contusions.

1H, 13C, and 15N resonance assignments and secondary structure analysis of the HU protein from Bacillus stearothermophilus using two- and three-dimensional double- and triple-resonance heteronuclear magnetic resonance spectroscopy.

Nearly complete 1H, 13C, and 15N resonance assignments have been obtained for the protein HU from Bacillus stearothermophilus (dimer, 19.5 kDa) using double- and triple-resonance 2D and 3D NMR experiments. This has resulted in assignments of 91% of the observable protons, 98% of all 13C, and 92% of all 15N nuclei. NOEs obtained from a 3D time-shared NOESY-(13C,15N)-HSQC spectrum, exchange data of amide protons, and chemical shifts of the 1H alpha, 1HN, 13C beta, 13C alpha, 13CO, and 15N nuclei have been used to identify the secondary structure elements. Three alpha-helices (residues 3-13, 18-37, and 83-90) and three extended strands (residues 40-45, 48-62, and 67-82) have been found in HU. The arrangement of these elements of secondary structure is very similar to the X-ray structure [Tanaka et al. (1984) Nature 310, 376-381; White et al. (1989) Proteins 5, 281-288]. The conformation of the proposed DNA-binding region of HU, i.e., an antiparallel beta-hairpin, was not observed previously in the X-ray structure. In the NMR structure long range NOEs in the beta-arm region (residues 53-76) suggest a distortion between residue Pro-72 and Ala-73 and between Pro-63 and Gln-64 with concomitant distortions in the opposite strand. The NOE data indicate further that the loop region in the DNA-binding arms of HU is arranged as a type I beta-turn from Pro-63 to Gly-66.