Effects of induced hypothermia after soft-tissue injury.

BACKGROUND: Hypothermia is occasionally employed to reduce the metabolic rate and to protect the brain in patients undergoing surgery, but it is controversial whether hypothermia (HT) is beneficial or harmful in trauma victims with soft-tissue injuries. For this purpose, we studied the acute effects of hypothermia induced after infliction of a standardized soft-tissue injury. METHODS: After a standardized high-energy gunshot wound to the right hind leg of 14 anesthetized piglets, the animals were randomized to normothermia or HT (30 degrees C) induced with a HT bed. The cardiovascular and hematological status was monitored for 6 h after the injury. RESULTS: The heart rate, mean arterial pressure, neutrophil count, and plasma adrenaline level were significantly lower in the HT pigs than in the controls (p<0.05). The arterial oxygen tension was significantly elevated in the HT group. Cardiac index and oxygen delivery decreased slightly in both groups, but no difference developed between the groups in these parameters. Serum potassium increased significantly in the controls (p<0.001). CONCLUSION: HT down to 30 degrees C following high-energy penetrating soft-tissue injury had a modest effect on the hemodynamics and oxygen delivery. However, evidence of 'stress' was reduced, and the pigs developed a progressive increase in their serum potassium concentration.

The effect of body mass and physical activity on the development of guinea pig osteoarthrosis.

We quantitatively evaluated the morphological and biochemical effects of body mass and physical activity on spontaneously developing guinea pig osteoarthrosis (OA). 6-month-old male guinea pigs were allocated to 3 groups: controls (C) living under standard laboratory conditions with food ad libitum; mobilized animals (M) allowed unrestricted motion in large rooms with food ad libitum; and a diet group (D) weight-matched with the M-group. At 9- and 12-months of age they were killed and the left proximal tibia was processed for quantitative histology and the right tibial articular cartilage for analyses of glycosaminoglycan (GAG). OA mostly occurred on the medial condyle's central part not covered by the meniscus. The thinnest cartilage was found in 12-month-old M-animals (M12), which had 60% of the central cartilage surface affected by lesions that extended down to the mineralized cartilage. C12 had 25% exposed mineralized cartilage and D12, 2%. Subchondral bone density followed the loading patterns--the highest in M12 and lowest in D12. M12 had the lowest cartilage GAG concentrations. Load appears to be a key external factor in guinea pig OA. An increase in physical activity may be chondroprotective in the early phase, but harmful when fibrillations eventually have developed. This is underscored by the extensive OA changes in M12, although these animals weighed about the same as D12 (which had the least extensive OA). Therefore, a reduction in body mass seems to retard the progression of OA in animals, which are mainly subjected to a static load (C12 and D12), but not sufficiently in animals with a more dynamic load (M12). Changes in morphological patterns are paralleled by changes in GAG concentration, which probably reflect the metabolic capacity of the cartilage.

Distribution of chondroitin 4-sulfate epitopes (2/B/6) in various zones and compartments of articular cartilage in guinea pig osteoarthrosis.

We studied changes in the morphology of tibial articular cartilage in early guinea pig osteoarthrosis (OA) at 6 and 12 months of age with quantitative light microscopy, and the distribution of chondroitin-4-sulfate with quantitative ultrastructural immunolabeling, using the 2/B/6 epitope. Labeling was correlated to previous chromatography findings concerning proteoglycan (PG) concentration in animals of the same age. The cell volume fraction had decreased at 12 months in the superficial zone of cartilage with OA (medial condyle) as well as in cartilage without OA (lateral condyle), being lower medially than laterally. The PG concentration differed between the zones and matrix compartments. Medially, a reduction in PG concentration occurred between 6 and 12 months in the interterritorial compartment of the two uppermost zones. Laterally, the concentrations increased. In general, the pericellular PG concentration was higher than the interterritorial in the two uppermost zones. The striking variation in structural and labeling responses in the various zones and compartments indicate a heterogeneous tissue response in guinea pig OA that will probably affect sampling in biochemical analyses of cartilage homogenates and synovial fluid.

Mechanisms of shock wave induced endothelial cell injury.

BACKGROUND AND OBJECTIVES: Medical procedures, for example, laser angioplasty and extracorporeal lithotripsy as well as high-energy trauma expose human tissues to shock waves (SWs) that may cause tissue injury. The mechanisms for this injury, often affecting blood vessel walls, are poorly understood. Here we sought to assess the role of two suggested factors, viz., cavitation or reactive oxygen species (ROS). STUDY DESIGN/MATERIALS AND METHODS: A laser driven flyer-plate model was used to expose human umbilical cord vein endothelial cell (HUVEC) monolayers to SWs or to SWs plus cavitation (SWC). Cell injury was quantified with morphometry, trypan blue staining, and release of (51)Cr from labeled HUVECs. RESULTS: HUVECs, exposed to SWs only, could not be distinguished from controls in morphological appearance or ability to exclude trypan blue. Yet, release of (51)Cr, indicated a significant cell injury (P < 0.05). HUVEC cultures exposed to SWC, exhibited cell detachment and cell membrane damage detectable with trypan blue. Release of (51)Cr was fourfold compared to SW samples (P < 0.01). Signs of cell injury were evident at 15 minutes and did not change over the next 4 hours. No protective effects of ROS scavengers were demonstrated. CONCLUSIONS: Independent of ROS, SWC generated an immediate cell injury, which can explain, for example, vessel wall perturbation described in relation to SW treatments and trauma.

Induced hypothermia after high-energy soft-tissue injury and subsequent hemorrhagic shock.

Many cases of hypothermia (HT) occur in trauma victims subjected to soft tissue injury and hemorrhage. The aim of the present study was to study the effects of HT on the combination of these insults. A standardized gunshot wound was inflicted on the right hind leg of 14 anesthetized piglets. They were then exsanguinated of 50% of their blood volume and randomized to normothermia or HT (30 degrees C). The animals were observed for 4 h after the injury with measurements of hemodynamics, oxygen consumption, and of plasma catecholamines and electrolytes. The insults reduced cardiac output and the arterial pressure by approximately 50%, but no further reduction occurred when HT was induced. The oxygen extraction ratio increased from approximately 35% to 75% in both groups. The gradual reduction of oxygen consumption in HT animals (P < 0.05) decreased the oxygen extraction ratio to around 50%. Heart rate, the serum potassium and creatinine concentrations, and the leukocyte counts were all maintained closer to baseline in the presence of HT. Hypothermia tended to decrease oxygen extraction and was associated with less evidence of tissue injury. These effects are potentially beneficial in soft-tissue trauma combined with hypovolemia.

The medical severity index of disasters

In 1980 an international working party postulated a definition for a disaster. later this concept was formulated into a classification and scoring system. This system has now been refined to be used prospectively during the management stage of a calamity. By calculating the medical severity index, which is the product of the casualty load and the severity of the incident, and comparing this figure with the available total capacity of the medical services, which is the medical rescue capacity, the medical transport capacity and the hospital treatment capacity, the dispatcher at the control center can fairly quickly and precisely identify if a calamity is to be regarded as a disaster or not and if the region can cope with the situation. Moreover a calculation of the hospital treatment capacity in the dimensions needed for the medical rescue capacity and medical transport capcity when planning how to deal with a disaster.(AU)

The terrorist bomb explosion in Bologna, Italy, 1980 : An analysis of the effects and injuries sustained

In August 1980 a terrorist bomb attack was made on the central railway station of Bologna, Italy. Altogether 291 persons were injuried, 73 of whom died at the scene. An analysis of the nature of the injuries and the mechanism by which they occurred showed that three types of bomb injuries could be distinguished: primary blast injuries (pulmonary injuries and flashburns), and secondary and tertiary injuries (concussions, lacerations, and fractures), the latter two types from flying debris set in motion by the blast wave or propulsion of the body. Chest X-ray should be included as a routine part of the examination of blast-injured patients on admission, since many of them develop respiratory insufficieney within 24 hours even when primary symptoms are mild. Because the secondary and tertiary effects of a bomb explosion often lead to multiple injuries, these patients require considerable therapeutic and medical care resources. By an evaluation of the degree of severity of the injuries with use of the AIS (Abbreviated Injury Scale) and ISS (Injury Severity Score) systems, the injurious effects of different types of disasters can be estimated and the findings can serve as a basis for future planning of disaster preparedness(AU)

The medical severity index of disasters

By calculating the medical severity index, which is the product of the casualty load and the severity of the incident, and comparing this figure with the available total capacity of the medical services, which is the medical rescue capacity, it is possible to be regarded as a disaster or not and if the region can cope with the situation. Moreover a calculation of the hospital treatment capacity in the region could serve as a guideline for estimation of the dimensions needed for the medical rescue and medical transport capacity when planning how to deal with a disaster