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The most-used safety recommendation for protective vests is that the impact should not cause more than a 44-mm impression in plasticine. The aim of this study was to investigate whether this criterion was sufficient if the vest was exposed to a high-velocity projectile. We tested the hypothesis with pigs divided into a 40-mm group (n = 10) and a 34-mm group (n = 8) protected by a vest allowing a 40-mm or 34-mm impression in plasticine, respectively. Five (50%) of 10 animals in the 40-mm group and 2 (25%) of 8 in the 34-mm group died due to the trauma. We observed severe lung hematoma, impaired circulation, desaturation, and electroencephalogram changes. These effects were more aggravated in the 40-mm group compared to the 34-mm group. Based on our results, the overall judgment is that the safety criterion of 44-mm impression is insufficient when a vest is exposed to a high-velocity projectile. [ABSTRACT FROM AUTHOR]

Behind armor blunt trauma (BABT) is a non-penetrating injury caused by the rapid deformation of body armor, by a projectile, which may in extreme circumstances cause death. The understanding of the mechanisms is still low, in relation to what is needed for safety threshold levels. Few models of graded kinetic energy transfer to the body exist. We established an experimental model for graded BABT. The cold gas cannon was air-driven, consisted of a pressure vessel, a barrel, and a pressure actuator. It required short training to operate and was constructed by standard components. It produced standardized expulsion of plastic projectiles with 65 mm and weight 58 g. Velocity correlated linearly to pressure (R 0.9602, p < 0.0001), equation Y = 6.558*X + 46.50. Maximum tested pressure was 10 bar, velocity 110 m/s and kinetic energy (E k ) 351 J. Crossbred male swine (n = 10) mean weight (SD) 56 ± 3 kg, were subjected to BABT, mean E k (SD) 318 (61) J, to a fix point on the right lateral thorax. Pulmonary contusion was confirmed by physiological parameters pO 2 (p < 0.05), SaO 2 (p < 0.01), pCO 2 (p < 0.01), etCO 2 (p < 0.01), MPAP (p < 0.01), Cstat (p < 0.01), intrapulmonary shunt (Q's/Q't) (p < 0.05), and qualified trans-thoracic ultrasound (p < 0.0001). The consistent injury profile enabled for the addition of future experimental interventions., (© 2023. The Author(s).)

Purpose: Pelvic and lower junctional hemorrhage result in a significant amount of trauma related deaths in military and rural civilian environments. The Abdominal Aortic and Junctional Tourniquet (AAJT) and infra-renal (zone 3) Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) are two options for resuscitation of patients with life threatening blood loss from and distal to the pelvis. Evidence suggest differences in the hemodynamic response between AAJT and zone 3 REBOA, but fluid management during resuscitation with the devices has not been fully elucidated. We compared crystalloid fluid requirements (Ringer's acetate) between these devices to maintain a carotid mean arterial pressure (MAP) > 60 mmHg., Methods: 60 kg anesthetized and mechanically ventilated male pigs were subjected to a mean 1030 (range 900-1246) mL (25% of estimated total blood volume, class II) haemorrhage. AAJT (n = 6) or zone 3 REBOA (n = 6) were then applied for 240 min. Crystalloid fluids were administered to maintain carotid MAP. The animals were monitored for 30 min after reperfusion., Results: Cumulative resuscitative fluid requirements increased 7.2 times (mean difference 2079 mL; 95% CI 627-3530 mL) in zone 3 REBOA (mean 2412; range 800-4871 mL) compared to AAJT (mean 333; range 0-1000 mL) to maintain target carotid MAP. Release of the AAJT required vasopressor support with norepinephrine infusion for a mean 9.6 min (0.1 µg/kg/min), while REBOA release required no vasopressor support., Conclusion: Zone 3 REBOA required 7.2 times more crystalloids to maintain the targeted MAP. The AAJT may therefore be considered in a situation of hemorrhagic shock to limit the need for crystalloid infusions, although removal of the AAJT caused more severe hemodynamic and metabolic effects which required vasopressor support., (© 2021. The Author(s).)

Trauma injury is the sixth leading cause of death worldwide, and interpersonal violence is one of the major contributors in particular regarding injuries to the head and neck. The incidence, demographics, and outcomes of penetrating trauma reaching hospitals in Sweden are not known. We report the largest, nationwide epidemiological study of penetrating injuries in Sweden, using the Swedish Trauma Registry (SweTrau). A multi-center retrospective descriptive study of 4,776 patients was conducted with penetrating injuries in Sweden, between 2012 and 2018. Due to the increase in coverage of the SweTrau registry during the same period, we chose to analyze the average number of cases for the time intervals 2013-2015 and 2016-2018 and compare those trends to the reports of the Swedish National Council for Crime Prevention (Brå) as well. A total of 663 patients had Injury Severity Score (ISS) ≥ 15 at admission and were included in the study. Three hundred and sixty-eight (55.5%) were stab wounds (SW), 245 (37.0%) gunshot wounds (GSW), and 50 (7.5%) other traumas. A majority of the cases involved injuries to the head, neck, and face. SW increased from 145 during 2013-2015 to 184 during the second period of 2016-2018. The increase was greater for GSW from 92 to 141 during the same respective periods. This trend of increase over time was also seen in head, neck, and face injuries. The 30-day mortality was unaffected (48-47%) in GSW and trended toward lower in SW (24-21%) when comparing 2013-2015 with 2016-2018. Patients with head trauma had 45% mortality compared to 18% for non-head trauma patients. Head trauma also resulted in worse outcomes, only 13% had Glasgow outcome score (GOS) 5 compared to 27% in non-head trauma. The increasing number of cases of both SW and GSW corresponded well with reports from Brå although further studies also are needed to address deaths outside of hospitals and not registered at the SweTrau. The majority of cases had injuries to the head, neck, and face and were associated with higher mortality and poor outcomes. Further studies are needed to understand the contributing factors to these worse outcomes in Sweden and whether more targeted trauma care of these patients can improve outcomes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Günther, Dahlberg, Rostami, Azadali, Arborelius, Linder and Rostami.)

Purpose. Behind armor blunt trauma (BABT) is a non-penetrating injury caused by the rapid deformation of body armor, by a projectile, which may in extreme circumstances cause death. The understanding of the mechanisms is still low, in relation to what is needed for safety threshold levels. High velocity projectile BABT causes immediate and severe hypoxia by increased venous admixture (Q's/Q't), but it is not known whether the level of hypoxia correlates to the kinetic energy (E k ) of the projectile. Materials and Methods. We constructed a 65 mm BABT-simulator to measure the E k absorbed by the thorax. The simulator was validated to 7.62 mm high velocity BABT (swine with removed organs) for 7.62 mm (n = 7) and 65 mm (n = 12). Physiological measurements during 60 minutes were performed in 40 anesthetized swine in groups control (n = 9), 7.62 mm (n = 7), 65 mm weight variation (n = 24), 65 mm speed variation (n = 12, included in the weight variation group). New calculations were done for a previously studied group of 7.62 mm with backing (n = 9). Results. 65 mm BABT simulation and 7.62 mm BABT had similar back-face signatures (24 mm), and maximum thoracic impression speed (24-34 m/s). Back-face signatures correlated linearly to E k (R 2 =0.20). Rib fractures had a 50% likelihood at back-face signature 23.0 mm (95% CI 18.5 to 29.0 mm, area under ROC curve 0.93). E k correlated linearly to pO 2 (R 2 =0.34, p = 0.0026) and venous admixture (R 2 =0.37, p = 0.0046). The extrapolated E k at 5 minutes for pO 2 =0 kPa was 587 J and for venous admixture = 100% 574 J. Conclusions. Hypoxia and venous admixture correlated linearly to E k , allowing for a calculated predicted lethal E k to ≥574 J, which should be verified in survival studies. Lethality predictions from lung physiology is an alternative to clay impressions and may facilitate the development of ballistic safety equipment and new BABT safety criteria.Supplemental data for this article is available online at https://doi.org/10.1080/01902148.2021.1950869 .

Most blast-induced traumatic brain injuries (bTBI) are mild in severity and culpable for the lingering and persistent neuropsychological complaints in affected individuals. There is evidence that the prevalence of symptoms post-exposure may be sex-specific. Our laboratory has focused on changes in the monoamine and the neuropeptide, galanin, systems in male rodents following primary bTBI. In this study, we aimed to replicate these findings in female rodents. Brainstem sections from the locus coeruleus (LC) and dorsal raphe nuclei (DRN) were processed for in situ hybridisation at 1 and 7 days post-bTBI. We investigated changes in the transcripts for tyrosine hydroxylase (TH), tryptophan hydroxylase two (TPH2) and galanin. Like in males, we found a transient increase in TH transcript levels bilaterally in the female LC. Changes in TPH2 mRNA were more pronounced and extensive in the DRN of females compared to males. Galanin mRNA was increased bilaterally in the LC and DRN, although this increase was not apparent until day 7 in the LC. Serum analysis revealed an increase in corticosterone, but only in exposed females. These changes occurred without any visible signs of white matter injury, cell death, or blood-brain barrier breakdown. Taken together, in the apparent absence of visible structural damage to the brain, the monoamine and galanin systems, two key players in emotional regulation, are activated deferentially in males and females following primary blast exposure. These similarities and differences should be considered when developing and evaluating diagnostic and therapeutic interventions for bTBI., (Copyright © 2020 Kawa, Arborelius, Hökfelt and Risling.)

β adrenergic receptors mediate effects via activation of G proteins, transactivation of membrane growth factor receptors, or β adrenergic receptor-β arrestin-facilitated scaffold-mediated signaling. Agonist occupancy of the β adrenergic receptor induces desensitization by promoting β adrenergic receptor kinase phosphorylation of the carboxyl terminal domain, facilitating binding of the amino terminal of the β arrestin, which sterically inhibits interactions between β adrenergic receptors and G proteins and induces clathrin-coated pit-mediated receptor endocytosis. Scaffold formation promoted by β arrestin binding to the β adrenergic receptor activates extracellular regulated kinase 1/2 in a manner which elicits cytosolic retention of, and prevents promotion of nuclear transcriptional activity by, mitogen-activated protein kinase. The β adrenergic receptor kinase also interacts with a yet to be determined microsomal membrane protein via high-affinity electrostatic interactions. We evaluate β adrenergic receptor structure, function, and downstream signaling and β arrestin-mediated desensitization, receptor endocytosis, and scaffold-facilitated signal transduction in order to illumine therapeutic strategies designed to modulate these pathways. We trust these approaches may arm us with the capacity to selectively modulate signal transduction pathways regulating cellular proliferation, immunogenicity, angiogenesis, and invasive and metastatic potential implicated in cancer initiation, promotion, and progression.

Background: Behind armor blunt trauma (BABT) is a non-penetrating injury caused by the rapid deformation of body armor, by a projectile, which may in extreme circumstances cause death. Although there is not a high incidence of high energy BABT, the understanding of the mechanisms is still low, in relation to what is needed for safety threshold levels. BABT is also useful as a model for blunt thoracic trauma, with a compressive speed between traffic accidents and blast caused by explosives. High velocity projectile BABT causes severe hypoxia. The mechanisms are not fully known. We investigated the acute pulmonary consequences in the individual lungs, and the effects of alveolar recruitment., Methods: 12 swine (mean weight 62.5 kg) were randomized to groups BABT by 7.62 × 51 mm NATO-type bullets (mean velocity 803 m/s) to a military grade ceramic plate armor (n = 7) or control (n = 5). Modified double lumen tracheal tubes provided respiratory dynamics in the lungs separately/intermittently for two hours, with alveolar recruitment after one hour., Results: Venous admixture increased 5 min after BABT (p < .05) and correlated with increased cardiac output. Static compliance decreased 5 minutes after BABT (p < .05) and further by recruitment (p < .005). Physiological dead space decreased 5 minutes after BABT (p < .01) and further by recruitment (p < .01), while not in the contralateral lung. V'A/Q' decreased 5 minutes after BABT (p < .05), also shown in phase III volumetric capnography (p < .05). Most effects regressed after one hour., Conclusions: High velocity projectile BABT caused hypoxia by a severe and transient decrease in V'A/Q' to <1 and increased venous admixture in the exposed lung. Alveolar recruitment was hemodynamically and respiratory tolerable and increased V'A/Q'. Body armor development should aim at ameliorating severe pulmonary consequences from high projectile velocities which also needs to include further understanding of how primary and secondary effects are distributed between the lungs.

Background: Vein of Galen aneurysmal malformations (VOGMs) are pial arteriovenous fistulas possessing Galenic venous drainage most commonly presenting during the neonatal period and infancy, with initial discovery during adulthood quite rare., Objectives and Methods: We conducted a literature survey of the PubMed database in order to identify Galenic pial arteriovenous fistulas (GPAVFs) with major manifestation or initial presentation during adulthood. Inclusionary criteria included pial AVFs with Galenic drainage with major manifestation or initial presentation at, or older than, 18 years. Exclusionary criteria included exclusive pediatric onset of symptomatology attributable to GPAVFs without a new onset major presentation during adulthood, exclusive or major dural arterial supply, arteriovenous malformations with Galenic drainage, developmental venous anomalies with Galenic drainage, isolated varices or anomalies of the vein of Galen, and any lesions with uncertainty regarding true GPAVF nature., Results: Our search generated 1589 articles. Excluding duplicates, 26 cases met criteria for evaluation. Mean age was 34.1 +/- 2.53 years. Clinical presentations of GPAVFs among adults included headache, intracranial hemorrhage, seizures, and focal neurologic deficits. Management strategies included observation (n = 5), emergent ventriculostomy or Torkildsen shunt (n = 3), cerebrospinal fluid diversion via ventriculoperitoneal shunting (n = 4), microsurgical obliteration or thrombectomy (n = 4), transarterial and/or transvenous embolotherapeutic obliteration (n = 7), and concurrent embolotherapy and radiosurgical irradiation (n = 1)., Conclusions: GPAVFs in adults often present with symptomatology of mild severity and may be effectively managed conservatively, though occasionally present catastrophically or may be treated via cerebrospinal fluid diversion, microsurgical obliteration, or endovascular embolization. Severity sufficient to require emergent intervention portended a poor outcome., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Severe thoracic trauma affects 55% of patients with multiple traumatic injuries and may lead to acute lung injury or acute respiratory distress syndrome. Pulmonary trauma differs clinically and biologically from lung injury of other origins and carries a mortality rate of 10%. Treatment options are limited, and it is not possible to monitor the progression of lung injury with specific biomarkers. Microdialysis of pleural fluid may offer a viable entry to monitor the lung directly and specifically. Bronchial microdialysis has been described, but not pleural microdialysis. We therefore investigated the feasibility of microdialysis of pleural fluid, and its ability to detect pulmonary injury and inflammation in the pleural cavity after traumatic acute lung injury. Methods: 16 pigs (mean weight 64 kg) were randomized to groups "exposed with MD", receiving a focally severe pulmonary contusion and microdialysis (n = 7), "control with MD", receiving only microdialysis and no pulmonary contusion (n = 5), "normal no MD" receiving only anesthesia (n = 2) and "naïve no MD" (no instrumentation) (n = 2). Microdialysate from the pleura and the perilesional subcutis, plasma and bronchoalveolar lavage were collected for 5 hours. Results: Pleura lactate, plasma lactate and pleura lactate/pyruvate ratio increased in injured lungs ( p  < 0.05). Subcutis and plasma glucose increased after trauma ( p  < 0.05). Pleura glycerol increased although not reaching statistical significance. IL-6 and IL-8 were dissimilar in plasma, bronchoalveolar lavage and pleural fluid, while IL-1 did not differ. Neutrophils increased in bronchoalveolar lavage ( p  < 0.001) after trauma, and in pleural fluid, although not when the microdialysis catheter was omitted. Conclusion: Pleural microdialysis was technically feasible and detected signs of cellular injury and anaerobic metabolism after focally severe pulmonary contusion and may be of interest for future clinical applications. The microdialysis catheter triggered a recruitment of neutrophils to the pleura which needs to be elucidated further before taking the technique into clinical practice.

Background: Traumatic hemorrhage remains a major cause of death in rural civilian and combat environments. Potential interventions to control hemorrhage from the pelvis and lower junctional regions include the abdominal aortic and junctional tourniquet (AAJT) and resuscitative endovascular balloon occlusion of the aorta (REBOA). The AAJT requires low technical skills and may thus be used by nonmedical professionals, but is associated with time-dependent ischemic complications. In combination with delayed patient evacuation, it may therefore be deleterious. Transition to zone 3 REBOA in higher levels of care may be a possibility to maintain hemostasis, mitigate adverse effects and enable surgery in patients resuscitated with the AAJT. It is possible that a transition between the interventions could lead to hemodynamic penalties. Therefore, we investigated the feasibility of replacing the AAJT with zone 3 REBOA in a porcine model of uncontrolled femoral hemorrhage., Methods: Domestic pigs (n = 12) averaging 57 kg were exposed to a class IV uncontrolled hemorrhage from the common femoral artery. The animals were randomized to 60-minute AAJT (n = 6) or 30-minute AAJT with transition to 30-minute zone 3 REBOA. Hemodynamic and metabolic parameters and ultrasonographic measurements of the common femoral artery were collected., Results: Transition from AAJT to zone 3 REBOA caused a significant decrease in mean arterial pressure (25 mm Hg). Hemostasis was maintained. The common femoral artery diameter decreased by 1.8 mm (38%) after hemorrhage and further 0.7 mm (23%) after aortic occlusion., Conclusion: Transition from AAJT to zone 3 REBOA after a class IV bleeding is feasible with hemodynamic support. Vascular access to the femoral artery for REBOA insertion poses a technical challenge after hemorrhage and AAJT application., Level of Evidence: Laboratory animal study, level IV.

Background: Uncontrolled hemorrhage is a leading cause of tactical trauma-related deaths. Hemorrhage from the pelvis and junctional regions are particularly difficult to control due to the inability of focal compression. The Abdominal Aortic and Junctional Tourniquet (AAJT) occludes aortic blood flow by compression of the abdomen. The survivability of tourniquet release beyond 120 minutes is unknown and fluid requirements to maintain sufficient blood pressure during prolonged application are undetermined. We therefore compared 60-minute and 240-minute applications and release of the AAJT for 30 minutes, with crystalloid fluid therapy, after a Class II hemorrhage., Methods: Sixty-kilogram anesthetized pigs were subjected to 900-mL hemorrhage and AAJT application for 60 minutes (n = 5), 240 minutes (n = 5), and fluid therapy only for 240 minutes (n = 5) and reperfusion for 30 minutes., Results: The AAJT application was hemodynamically and respiratory tolerable for 60 minutes and 240 minutes. Cumulative fluid requirements decreased by 64%, comparable to 3000 mL of crystalloids. Mechanical ventilation was impaired. AAJT increased the core temperature by 0.9°C compared with fluid therapy. Reperfusion consequences were reversible after 60 minutes but not after 240 minutes. A 240-minute application resulted in small intestine and liver ischemia, persisting hyperkalemia, metabolic acidosis, and myoglobinemia, suggesting rhabdomyolysis., Conclusion: The AAJT application for 240 minutes with reperfusion was survivable in an intensive care setting and associated with abdominal organ damage. Long time consequences and spinal cord effects was not assessed. We propose an application time limit within 60 minutes to 240 minutes, though further studies are needed to increase the temporal resolution. The AAJT application may be considered as a rescue option to maintain central blood pressure and core temperature in cases of hemorrhagic shock from extremity bleedings, if fluid therapy is unavailable or if the supply is limited., Level of Evidence: Therapeutic study, level II.

Repeated mild blast-induced traumatic brain injury (rmbTBI), caused by recurrent exposure to low levels of explosive blast, is a significant concern for military health systems. However, the pathobiology of rmbTBI is currently poorly understood. Animal models are important tools to identify the molecular changes of rmbTBI, but comparisons across different models can present their own challenges. In this study, we compared two well-established rodent models of mbTBI, the "KI model" and the "USU/WRAIR model." These two models create different pulse forms, in terms of peak pressure and duration. Following single and double exposures to mild levels of blast, we used in situ hybridization (ISH) to assess changes in mRNA levels of tyrosine hydroxylase (TH), tryptophan hydroxylase (TPH2), and galanin in the locus coeruleus (LC) and dorsal raphe nucleus (DRN). These systems and their transmitters are known to mediate responses to stress and anxiety. We found increased mRNA levels of TH, TPH2 and galanin in the LC and DRN of single-exposed rats relative to sham rats in the KI but not the USU/WRAIR model. Sham mRNA values measured in the USU/WRAIR model were substantially higher than their KI counterparts. Double exposure caused similarly significant increases in mRNA values in the KI model but not the USU/WRAIR model, except TPH2 and galanin levels in the DRN. We detected no cumulative effect of injury in either model at the used inter-injury interval (30 min), and there were no detectable neuropathological changes in any experimental group at 1 day post-injury. The apparent lack of early response to injury as compared to sham in the USU/WRAIR model is likely caused by stressors (e.g., transportation and noise), associated with the experimental execution, that were absent in the KI model. This study is the first to directly compare two established rodent models of rmbTBI, and to highlight the challenges of comparing findings from different animal models. Additional studies are needed to understand the role of stress, dissect the effects of psychological and physical injuries and to identify the window of increased cerebral vulnerability, i.e., the inter-injury interval that results in a cumulative effect following repeated blast exposure.

The symptomatology, mood and cognitive disturbances seen in post-traumatic stress disorder (PTSD) and mild blast-induced traumatic brain injury (mbTBI) overlap considerably. However the pathological mechanisms underlying the two conditions are currently unknown. The neuropeptide galanin has been suggested to play a role in the development of stress and mood disorders. Here we applied bio- and histochemical methods with the aim to elucidate the nature of any changes in the expression of galanin and its receptors in a rodent model of mbTBI. In situ hybridization and quantitative polymerase chain reaction studies revealed significant, injury-induced changes, in some cases lasting at least for one week, in the mRNA levels of galanin and/or its three receptors, galanin receptor 1-3 (GalR1-3). Such changes were seen in several forebrain regions, and the locus coeruleus. In the ventral periaqueductal gray GalR1 mRNA levels were increased, while GalR2 were decreased. Analysis of galanin peptide levels using radioimmunoassay demonstrated an increase in several brain regions including the locus coeruleus, dorsal hippocampal formation and amygdala. These findings suggest a role for the galanin system in the endogenous response to mbTBI, and that pharmacological studies of the effects of activation or inhibition of different galanin receptors in combination with functional assays of behavioral recovery may reveal promising targets for new therapeutic strategies in mbTBI., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Exposure to improvised explosive devices can result in a unique form of traumatic brain injury--blast-induced traumatic brain injury (bTBI). At the mild end of the spectrum (mild bTBI [mbTBI]), there are cognitive and mood disturbances. Similar symptoms have been observed in post-traumatic stress disorder caused by exposure to extreme psychological stress without physical injury. A role of the monoaminergic system in mood regulation and stress is well established but its involvement in mbTBI is not well understood. To address this gap, we used a rodent model of mbTBI and detected a decrease in immobility behavior in the forced swim test at 1 d post-exposure, coupled with an increase in climbing behavior, but not after 14 d or later, possibly indicating a transient increase in anxiety-like behavior. Using in situ hybridization, we found elevated messenger ribonucleic acid levels of both tyrosine hydroxylase and tryptophan hydroxylase 2 in the locus coeruleus and the dorsal raphe nucleus, respectively, as early as 2 h post-exposure. High-performance liquid chromatography analysis 1 d post-exposure primarily showed elevated noradrenaline levels in several forebrain regions. Taken together, we report that exposure to mild blast results in transient changes in both anxiety-like behavior and brain region-specific molecular changes, implicating the monoaminergic system in the pathobiology of mbTBI.

Objective: Histological evaluation of porcine posterior cervical muscles after a forceful translational and extensional head retraction simulating high-speed rear end impact., Methods: Four anesthetized pigs were exposed to a cervical spine distortion (CSD)-like motion in a lying position. After 2 different survival times of 4 and 6 h (posttrauma), the pigs were euthanized and tissue sampling of posterior cervical muscles was performed. A standard histological staining method involving paraffin-embedded sections was used to analyze the muscles, focusing on injury signs like hemorrhage and inflammatory cell reaction. A pig that was not subjected to impact was used as a control pig and was subjected to the same procedure to exclude any potential artifacts from the autopsy., Results: The differentiation of 8 different posterior neck muscles in the dissection process was successful in more than 50 percent for each muscle of interest. Staining and valid analysis was possible from all extracted samples. Muscle injuries to the deepest posterior neck muscles could be found, especially in the musculus obliquus samples, which showed laminar bleedings in 4 out of 4 samples. In addition, in 4 out of 4 samples we were able to see increased cellular reactions. The splenius muscle also showed bleeding in all 4 samples. All animals showed muscle injury signs in more than three quarters of analyzed neck muscles. Differences between survival times of 4 and 6 h in terms of muscular injury were not of primary interest and could not be found., Conclusions: By simulating a CSD-like motion we were able to confirm injuries in the posterior cervical muscles under severe loading conditions. Further studies need to be conducted to determine whether these muscle injuries also occur under lower exposure forces.

Background: Injured lungs are sensitive to fluid resuscitation after trauma. Such treatment can increase lung water content and lead to desaturation. Hypertonic saline with dextran (HSD) has hyperosmotic properties that promote plasma volume expansion, thus potentially reducing these side effects. The aim of this study was to (1) evaluate whether fluid treatment counteracts hypotension and improves survival after nonhemorrhagic shock caused by lung contusion and (2) analyze whether resuscitation with HSD is more efficient than treatment with Ringer's acetate (RA) in terms of blood oxygenation, the amount of lung water, circulatory effects, and inflammatory response., Methods: Twenty-nine pigs, all wearing body armor, were shot with a 7.62-mm assault rifle to produce a standardized pulmonary contusion. These animals were allocated into three groups: HSD, RA, and an untreated shot control group. Exposed animals were compared with animals not treated with fluid and shot with blank ammunition. For 2 hours after the shot, the inflammatory response and physiologic parameters were monitored., Results: The impact induced pulmonary contusion, desaturation, hypotension, increased heart rate, and led to an inflammatory response. No change in blood pressure was observed after fluid treatment. HSD treatment resulted in significantly less lung water (p < 0.05) and tended to give better Pao2 (p = 0.09) than RA treatment. Tumor necrosis factor-α release and heart rate were significantly lower in animals given fluids., Conclusion: Fluid treatment does not affect blood pressure or mortality in this model of nonhemorrhagic shock caused by lung contusion. However, our data indicate that HSD, when compared with RA, has advantages for the injured lung.

Background: Behind armor blunt trauma (BABT) is defined as the nonpenetrating injury resulting from a ballistic impact on body armor. Some of the kinetic energy is transferred to the body, causing internal injuries and, occasionally, death. The aim of this study was to investigate if apnea and other pathophysiological effects after BABT is a vagally mediated reflex., Methods: Sixteen anesthetized pigs wearing body armor, of which five were vagotomized, were shot with a standard 7.62 mm assault rifle. These animals were compared with control animals (n = 8), shot with blank ammunition. We performed bilateral vagotomy before the shot and assessed the outcome on the apnea period, respiration, circulation, and brain function. Animals were monitored during a 2-hour period after the shot., Results: Nonvagotomized animals had a mean apnea period of 22 (6-44) seconds. This group also showed a significant decrease in oxygen saturation compared with control animals. Furthermore, electroencephalogram-changes were more pronounced in nonvagotomized animals. In contrast, vagotomized animals were protected from apnea and showed only a minor decrease in oxygen saturation. All exposed animals showed impaired circulation, and postmortem examination revealed a pulmonary contusion., Conclusion: This study shows that apnea after BABT is a vagally mediated reflex that can be inhibited by bilateral vagotomy. Our results indicate that the initial apnea period is an important factor for hypoxia after BABT. Supported ventilation should begin immediately if the affected person is unconscious and suffers from apnea. It should continue until the neurologic paralysis disappears and sufficient spontaneous breathing begins.

Background: Behind armor blunt trauma (BABT) is defined as the nonpenetrating injury resulting from a ballistic impact on personal body armor. The protective vest may impede the projectile, but some of the kinetic energy is transferred to the body, causing internal injuries and occasionally death. The aim in this study was to investigate changes in electroencephalogram (EEG) and physiologic parameters after high-velocity BABT., Methods: Eight anesthetized pigs, wearing body armor (including a ceramic plate) on the right side of their thorax, were shot with a 7.62-mm assault rifle (velocity approximately 800 m/s). The shots did not penetrate the armor and these animals were compared with control animals (n = 4), shot with blank ammunition. EEG and several physiologic parameters were thereafter monitored during a 2-hour period after the shot., Results: All animals survived during the experimental period. Five of the exposed animals showed a temporary effect on EEG. Furthermore, exposed animals displayed decreased cardiac capacity and an impaired oxygenation of the blood. Postmortem examination revealed subcutaneous hematomas and crush injuries to the right lung., Conclusion: The results in our animal model indicate that high-velocity BABT induce circulatory and respiratory dysfunction, and in some cases even transient cerebral functional disturbances.

The electromyogram and posture angles of the shoulder and arm were recorded during sitting manipulative work in three positions, with and without the forearm suspended by a balancer. A Selspot system was used to record movements. The results from 12 female subjects (mean age 29 yr) showed that the activity in deltoideus anterior decreased significantly by using a balancer. Lower mean values were also noted for deltoideus lateralis and the trapezius muscles. The neck inclination increased with higher work area position, but was independent of the use of a balancer.

The aim of this study was to evaluate different arm supports by comparing the activity of shoulder and arm muscles during various work tasks, with and without the lower arm supported. Twelve female subjects, aged between 23 and 37 years, were asked to perform three types of tasks: typing, simulated assembly work (in two different positions), and pipetting. The supports used were: fixed arm support (FIX), horizontal movable arm support (HOR), and spring-loaded arm support (SLA). During the experiments, the electromyograms (EMG) of four muscles were simultaneously recorded: m. deltoideus anterior and lateralis, m. trapezius pars descendens and m. extensor carpi radialis brevis. Normalization was made against maximum isometric contraction. The mean values of the normalized EMG levels showed a reduced EMG level of the shoulder muscles when using arm supports in all the tasks, and for all muscles but the wrist extensor, compared to the EMG levels without arm supports. The horizontal movable support was more effective in reducing the EMG levels of the shoulder muscles than other arm supports, in tasks at table height. Thus, it is possible to reduce muscle activity of the shoulder region by using arm supports. Further research is needed to make biomechanical calculations to compare the EMG level of these muscles using suspension and the effects of inclination of work task.

The aim of this study was to determine the power output and work done by different muscle groups at the hip and knee joints during a rising movement, to be able to tell the degree of activation of the muscle groups and the relationship between concentric and eccentric work. Nine healthy male subjects rose from a chair with the seat at knee level. The moments of force about the hip and knee joints were calculated semidynamically. The power output (P) and work in the different muscle groups surrounding the joints was calculated as moment of force times joint angular velocity. Work was calculated as: work = integral of P dt. The mean peak concentric power output was for the hip extensors 49.9 W, hip flexors 7.9 W and knee extensor 89.5 W. This power output corresponded to a net concentric work of 20.7 J, 1.0 J and 55.6 J, respectively. There was no concentric power output from the knee flexor muscles. Energy absorption through eccentric muscle action was produced by the hip extensors and hip flexors with a mean peak power output of 4.8 W and 7.4 W, respectively. It was concluded that during rising, the hip and knee muscles mainly worked concentrically and that the greatest power output and work were produced during concentric contraction of the knee and hip extensor muscles. There was however also a demand for eccentric work by the hip extensors as well as both concentric and eccentric work by the hip flexors. The knee flexor muscles were unloaded.

Unlabelled: Nine healthy male subjects and 8 patients with unilateral knee osteoarthrosis were studied while rising from a chair with and without the aid of a spring-loaded flap seat. The seat force started at 216 N and decreased with increasing seat angle. Ground reaction forces and motion were recorded using a force plate and video. EMG of the left vastus lateralis muscle was recorded. The effort when rising was estimated by the Borg scale. The use of the flap seat reduced the mean peak knee moment for the healthy subjects from 73 to 41 Nm and for the patients from 55 to 33 Nm. The decreases were significant at a p < 0.001 level. The patients also reduced their hip moment significantly from 50 to 35 Nm (p < 0.005). The muscle activity in the vastus lateralis was also significantly lower when the flap seat was used (p < 0.005). When the theoretically maximal friction force between seat and subject was added, the effective seat force decreased more slowly, and the relation between its horizontal and vertical force components was more advantageous. The patients estimated greater effort reduction than the healthy subjects comparing the ordinary chair and the flap seat., Conclusion: a spring-loaded flap seat can reduce knee and hip load and can thus be useful for people with knee osteoarthrosis.

Nine healthy male subjects rose from four different stools. The 'ordinary' stool (K) was set at normal chair height, approximately 50 cm, and the 'low ordinary' stool (O), the one-legged stool (T), and the pneumatically-sprung stool (S) were all approximately 32 cm high. The moments of force in the hip, knee, and ankle joints were calculated with a semidynamic technique using a Kistler force plate and video. EMG in four leg muscles was recorded. The part of bodyweight carried by the different stools when the subjects were sitting was measured, and the subjects estimated the effort of rising, using the Borg scale. The low ordinary stool gave higher knee and hip moments than the ordinary stool. Use of the pneumatic stool reduced the knee and hip moments to a level comparable with that of the ordinary stool. The reduction in moment compared with the one-legged stool (T) and the low ordinary stool (O) was significant, both in the knee (p < 0.005) and the hip (p < 0.001). Rising from the three low stools gave no significant differences in mean maximum muscle activity in any of the muscles investigated. The subjects estimated that the pneumatic stool and the ordinary stool were the easiest to rise from. The part of bodyweight carried by the ordinary stool and the low ordinary stool, both around 80% when sitting, was significantly higher than for the two other stools (p < 0.005). It was concluded that a pneumatic stool can be a useful device to workers who work in low positions and rise frequently.

The loading moments of force about the hip and knee joints of ten healthy male subjects were calculated using recorded forces from a force plate and static contribution from body segments. The subjects rose from a chair while using armrests in ten different ways, and, as a reference, without arm aid. The influence of different armrest heights, hand placements and arm forces was studied. Horizontal and vertical forces on the armrests were measured. Irrespective of armrest height and hand placement, the use of armrests significantly reduced the hip and knee moments compared to rising without arm aid (P < 0.001). However, there were no statistically significant differences between different armrest heights or hand placements. High arm force reduced both hip and knee moments. The greatest reduction occurred for high armrests and high arm force, which reduced the mean peak hip moment from 39 to 17 N m and the knee moment from 83 to 28 N m. Calculation of patellofemoral compressive force and the force on the femoral head due to extensor muscle activity demonstrated that local hip and knee forces were reduced when armrests were used. Horizontal forces applied to the armrests were small. Subjectively 'doubled' arm force resulted in nearly double force on the armrests., (Copyright © 1993. Published by Elsevier Ltd.)

The loading moment of force on the hip, knee, and ankle joints of nine healthy men rising from four different types of stools were compared, together with the levels of myoelectrical activity (EMG) in four leg muscles. Two types of stool (stand stools) had higher seats than a normal chair. The other two were of ordinary seat height, but one also had armrests. The bodyweight carried by the different stools when sitting was also measured, and the subject estimated the effort required for each trial. The mean maximum knee moment was over 60% lower when rising from the high stool than from 'ordinary' seat height. The difference between the high and low stand stool was also significant (p less than 0.001). Using the high stool or help of the arms reduced the mean maximum hip moment by about 50%. The mean maximum ankle moment was only marginally influenced by the different stools. Knee moment was influenced more by seat height than was hip moment. Vastus lateralis activity was significantly higher when subjects rose from 'ordinary' height than when rising from either stand stool (p less than 0.001). The rectus femoris muscle was little activated and the semitendinosus muscle was activated earlier when rising from higher seat heights. All subjects estimated the effort of rising from the higher stand stool to be lower than from the lower stand stool or from 'ordinary' height without arm rests. It was concluded that stand stools are good alternatives for workers who change frequently between sitting and standing work.

Biomechanical calculations of loads on the locomotor system in lifting tasks are often based on static models. Several investigators have shown, though, that in a dynamic act like lifting, inertial effects are not generally negligible. A complete dynamic analysis includes the calculation of linear and angular accelerations of body segments and is rather complicated to carry out. So it was of interest to find out whether the contribution of single body segments to the dynamic effects of the whole body might be negligible. Ten male subjects lifted a 12.8 kg box using two different techniques and two speeds. Ground reactions and body segment movements were recorded and reaction forces and net moments at different joints were calculated with static, dynamic and 'semidynamic' methods. The latter method incorporated the ground reaction forces as measured from a force plate but was otherwise equal to the static method. The results from semidynamic analyses agreed well with those from complete dynamic analyses for the ankle, knee, hip, and L5/S1 joints. For example, the semidynamically calculated peak moments at L5/S1 differed on average less than 3% from the dynamically calculated values. The contributions of the lower extremities and the pelvis to the dynamic effects of the whole body seemed to be quite small. The less complicated semidynamic method offers a good alternative to a fully dynamic analysis for estimations of peak moments in the lower back, at least for the studied lifting techniques.

Existing studies of shoulder joint loading, muscle strength and muscular activity do not, from the point of view of clinical application, adequately cover these factors, knowledge of which is important for the design of optimal exercises for training shoulder impairments. In the present study, exercises using a weight-and-pulley device have been analysed in order to map the resistance moments of force in relation to the muscular strength capacity of shoulder internal rotators , and to map the activation of these muscles in response to the resistance from the device. The relationships established in the study provide a basis for optimising various types of shoulder training exercises. For example, an angle of 40 degrees between frontal plane and shoulder-pulley line has been found to give the best adaptation of resistance to strength. The study also demonstrates the possibility of using a pulley apparatus for shoulder inward rotator muscle training.

The aim of this study was to calculate the magnitude of the instantaneous muscular power output at the hip, knee and ankle joints during ergometer cycling. Six healthy subjects pedalled a weight-braked bicycle ergometer at 120 watts (W) and 60 revolutions per minute (rpm). The subjects were filmed with a cine camera, and pedal reaction forces were recorded from a force transducer mounted in the pedal. The muscular work at the hip, knee and ankle joint was calculated using a model based upon dynamic mechanics described elsewhere. The mean peak concentric power output was, for the hip extensors, 74.4 W, hip flexors, 18.0 W, knee extensors, 110.1 W, knee flexors, 30.0 W and ankle plantar flexors, 59.4 W. At the ankle joint, energy absorption through eccentric plantar flexor action was observed, with a mean peak power of 11.4 W and negative work of 3.4 J for each limb and complete pedal revolution. The energy production relationships between the different major muscle groups were computed and the contributions to the total positive work were: hip extensors, 27%; hip flexors, 4%; knee extensors, 39%; knee flexors, 10%; and ankle plantar flexors 20%.

The load on the knee joints during lifting has been less studied than low back load. Healthy subjects lifted a 12.8-kg box from floor to table-level in three different ways; 1) with straight knees, 2) with bent knees and the box in front of the knees, and 3) with bent knees and the box between the knees. The loading moment of force about the bilateral knee axis was calculated by means of a computerized static sagittal plane model. Electromyography was recorded from quadriceps and ischiocrural muscles. The beginning of the flexed-knee lifts caused a flexing loading knee moment of about 50 Nm and a knee angle of 90 degrees. Straight-knee lifts gave all through the lift an extending loading moment. During the final phase of all lifts there was an extending loading knee moment of about 55 Nm and a knee angle of 0 degrees. The three lifts were compared and discussed from a biomechanical and ergonomical point of view.

The mechanical load on the gleno-humeral joint and the muscular activity during shoulder external rotation resisted by a pulley apparatus were analysed using normalized, low-pass-filtered EMG recorded from the infraspinatus, deltoid, pectoralis major and trapezius muscles. The load moment about the longitudinal axis of the joint was compared with the distribution of maximum muscle moment over different angles throughout the range of motion. The effect of subject positioning on the joint load and the muscular activity was studied. The best adaptation between the curves for load moment and maximum muscle moment was obtained when the subject was positioned sitting with the pulley located 20 degrees posterior to a frontal plane through the shoulders at a distance of 1.3 m from the joint. Of the four muscles investigated, the infraspinatus was the most active. The method described might be used to find optimal designs of shoulder external rotation exercises with special regard to avoiding unintentional overloading of joint structures weakened by disease or trauma.

The aim of this study was to evaluate the effects on the levels on neck and shoulder muscular activity of ergonomic aids used to support or suspend the arm in different sitting postures, both with and without movement of the arm-hand. Ten skilled women workers performed a standardized simulated work cycle similar to assembling printed circuit boards, in different sitting postures with and without ergonomic aids. The elbow was supported by a loosely-mounted, padded plate. For suspension, a new device, the K-block, was used giving an adjustable, constant suspending force. Full-wave rectified, low-pass filtered, time-averaged and normalized EMG was used. Surface electrodes were applied over six neck and shoulder muscles. The results show that a reduction in the level of activity in neck and shoulder muscles can be obtained with either aid. The reduction, whether caused by suspension or support of the arm, was related to the sitting posture. Elbow support might be more efficient than arm suspension in a sitting posture with the whole spine flexed, while arm suspension might be more efficient when the trunk is inclined slightly backward. Elbow support and, particularly, arm suspension may thus be recommended as technical aids in sedentary assembly work for patients with easily elicited cervical spine and/or shoulder pain. It is also suggested that arm suspension may be used to improve ergonomic conditions at workplaces.

The aim of the present study was to investigate how different ways of using a weight-and-pulley-circuit (wpc) influence the mechanics of a joint with adjacent muscles. A formula for the resisting moment with respect to a joint was developed and used in a computer model. The resistive effect of various modes of application of the wpc was calculated. It is shown how the resisting moment is influenced by changes of the following factors: 1) Angle between the horizontal plane and a line between joint and pulley (height of position of pulley); 2) Distance between joint and pulley; 3) Weight applied to the rope of the wpc; 4) Weight of the limb.

The maximum isometric extensor muscle strength was measured in 10 healthy subjects of different combinations of hip and knee angles. An ordinary exercise device was used for the measurements and the method could be useful in clinical work. The results revealed that the knee angle does not affect the hip extensor strength. The highest extensor muscular moments occurred at 90 degrees hip flexion, decreasing with decreasing hip angle. The distribution of the strength over the motion sector differed between male and female. The weight of the body segments was found to utilize 10-24% of the maximum strength at hip angles 60 degrees-0 degrees with subjects in a prone position.

When a patient with a musculoskeletal disorder returns to work after rehabilitation, the work-station should be designed so that the impaired muscle groups are less exposed to load. The work posture desirable for a particular muscle group might impose higher load on another muscle group. Since the shoulder muscles usually are stronger than the elbow muscles, a direct comparison of the loads is difficult. To make comparisons possible, the load moment about the investigated joints were divided by the counteracting maximum muscular moments, and a Muscular strength Utilization Ratio (MUR) was obtained. Using this principle, the muscular load on the shoulder and elbow was investigated in 72 different packing work postures. Different combinations of box size, box angle, edge height and weight of object handled were studied. There was a higher relative load on the shoulder than on the elbow. The concept of relating joint load to strength may serve as a guideline for how high a patient's strength should be before returning to work to avoid further injuries.

The load on the hip joint and activation of the gluteus maximus, hamstrings, adductor magnus and rectus femoris muscles during rising exercises including different adaptive adjustments were investigated in nine healthy subjects. The joint load was calculated from forces recorded with a force-measuring platform and pictures on cine-film. Levels of muscular activity were recorded with rectified, low-pass filtered, time-averaged and normalized EMGs. The loading moment about the hip joint was about 45 Nm during the initial part of the rising exercise, decreasing with smaller hip angle. Increase of the backward inclination of the trunk increased the load moment, which was maintained at about the same level during the rising exercise. Two adaptive adjustments lowered the joint load: foot position further backward and reduced resistance from the device. Foot position further forward increased the joint load. The levels of muscular activity in the hip extensors were low to medium and were slightly increased by posterior foot position and increased resistance from the device. Increased backward trunk inclination increased the activity in the final part of the rising exercise.

The load on the hip joint during lifting was studied. Healthy subjects lifted a 12.8 kg box from floor to table level with straight and flexed knees in four different ways. The loading moment of force about the bilateral hip axis was calculated by means of a computerized static sagittal plane model. The highest load moment, 124 Nm, occurred initially in the straight knee lift and the compressive joint reaction force was 2.7 times body-weight. The lowest load moment, 82 Nm, occurred in the flexed knee lift with the burden moved close to the trunk, the compressive force was 3.2 X bw. The load moment was also discussed in relation to the strength capability. The EMG levels of seven different hip muscles were normalized and expressed as a percentage of the recorded level of each muscle group during an isometric maximum voluntary contraction. The initial activity in the hamstrings was higher in the straight knee lift compared to flexed knees. The gluteus maximus was activated to a moderate level.

The aim of this study was to investigate load on shoulder joint and muscles in healthy adults during four different ways of lifting a moderate burden (12.8 kg) from floor to table level. The methods used were surface electrode EMG with linear envelope, and calculation of loading moments of force using a static biomechanical model. The shoulder load at the beginning of the lift was lowest for the straight knee lift. The peak load occurred in the late phase of all lifts. On completion of the lift, load and activation were considerably lower when the subject was allowed to step forward before putting the box down. The most activated shoulder muscles were the anterior and lateral parts of the deltoid, and the serratus anterior. Around 80% of the shoulder load moment was caused by the weight of the burden. Some 75% of maximum shoulder strength was required for lifting the burden.

The aim of the study was to investigate which muscles contract (and to what extent) during diagonal shoulder movements resisted by a weight-and-pulley-circuit and the relationship between the calculated resisting moment of force and the maximum voluntary isometrical muscular moment. EMG, mechanical calculations and measurements of moments of force were used. With the resistance used in the study, flexion-abduction-external rotation (FLABER) highly activated all three parts of the deltoideus muscle and the infraspinatus. Flexion-adduction-external rotation (FLADER) highly activated the anterior and middle parts of the deltoideus, infraspinatus and moderately the sternocostal part of the pectoralis major. Extension-abduction-internal rotation (EXABIR) highly activated the posterior deltoideus and moderately the latissimus dorsi. Extension-adduction-internal rotation (EXADIR) highly activated the sternocostal part of the pectoralis major.

The aim of the study was to analyze the effect of different sitting postures on the level of activity in some neck and shoulder muscles in a standardized work cycle involving movement of the arm/hand. Ten experienced female workers volunteered in a laboratory study. Full-wave rectified, low-pass filtered, time-averaged and normalized e.m.g. was used. Surface electrodes were applied unilaterally at six locations. The course of the level of muscle activity during the standardized work cycle is presented. There was a tendency to higher level of activity when the arm/hand was moving along the high part of the work object compared to along the low part. The level of activity during the standardized work movement with the arm/hand was significantly influenced by the sitting postures chosen. The highest activity levels were found in the posture with the whole spine flexed. A marked reduction of the level of activity was obtained when a posture with the thoraco-lumbar spine slightly inclined backward was used., (Copyright © 1987. Published by Elsevier Ltd.)