Weathersby. Natural history of severe decompression sickness after rapid ascent from air saturation in a porcine model. J Appl Physiol 89: 791-798, 2000.-We developed a swine model to describe the untreated natural history of severe decompression sickness (DCS) after direct ascent from saturation conditions. In a recompression chamber, neutered male Yorkshire swine were pressurized to a predetermined depth from 50-150 feet of seawater [fsw; 2.52-5.55 atmospheres absolute (ATA)]. After 22 h, they returned to the surface (1 ATA) at 30 fsw/min (0.91 ATA/min) without decompression stops and were observed. Depth was the primary predictor of DCS incidence (R ϭ 0.52, P Ͻ 0.0001) and death (R ϭ 0.54, P Ͻ 0.0001). Severe DCS, defined as neurological or cardiopulmonary impairment, occurred in 78 of 128 animals, and 42 of 51 animals with cardiopulmonary DCS died within 1 h after surfacing. Within 24 h, 29 of 30 survivors with neurological DCS completely resolved their deficits without intervention. Pretrial Monte Carlo analysis decreased subject requirement without sacrificing power. This model provides a useful platform for investigating the pathophysiology of severe DCS and testing therapeutic interventions. The results raise important questions about present models of human responses to similar decompressive insults.

To plan for any future rescue of personnel in a disabled and pressurized submarine, the US Navy needs a method for predicting risk of decompression sickness under possible scenarios for crew recovery. Such scenarios include direct ascent from compressed air exposures with risks too high for ethical human experiments. Animal data, however, with their extensive range of exposure pressures and incidence of decompression sickness, could improve prediction of high-risk human exposures. Hill equation dose-response models were fit, by using maximum likelihood, to 898 air-saturation, direct-ascent dives from humans, pigs, and rats, both individually and combined. Combining the species allowed estimation of one, more precise Hill equation exponent (steepness parameter), thus increasing the precision associated with human risk predictions. These predictions agreed more closely with the observed data at 2 ATA, compared with a current, more general, US Navy model, although the confidence limits of both models overlapped those of the data. However, the greatest benefit of adding animal data was observed after removal of the highest risk human exposures, requiring the models to extrapolate.

The United States military remains engaged in the longest armed conflict in this nation's history. The majority of casualties in the global war on terror come from blast-related injuries. Multiple centers have published their experience and outcomes with these complex patients. Findings from the study of injured military personnel have implications for mass casualty events resulting from industrial accidents or terrorism in the civilian sector. This article will review the pathophysiology of blast-related injury. The authors will summarize treatment considerations, priorities, and techniques that have proven successful. Finally, the authors will discuss the incidence and management of common complications after blast-related injuries.

Background Through-knee amputation is a common amputation level after battlefield injuries during the medical evacuation process. However, there are limited data comparing through-knee amputation with transfemoral amputation as a definitive amputation level in terms of gait parameters. Questions/purposes (1) Does through-knee amputation result in improved gait velocity when compared with matched transfemoral amputees? (2) Do through-knee amputees have a faster gait cadence than matched transfemoral amputees? (3) Do through-knee amputees have a different stride length or stride width than matched transfemoral amputees? (4) Does through-knee amputation result in decreased work of ambulation when compared with matched transfemoral amputees? Methods Between January 2008 and December 2012, six male active-duty military patients who had undergone unilateral through-knee amputations as a result of trauma underwent gait studies at our institution. Of those, four of six underwent gait analysis after being able to walk for at least 3 months without assistive devices, and this group was studied here. Most through-knee amputees who were not included had elective revisions of their amputations from through-knee to a transfemoral amputation before completing 3-month gait data. Each of the amputees studied was matched to a transfemoral amputee based on height, body mass index, and contralateral amputation level resulting in a case-control study of active-duty Each author certifies that neither he or she, nor any member of his or her immediate family, has funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research® neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA-approval status, of any drug or device prior to clinical use. Each author certifies that his or her institution approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.