Recommended medical and non-medical factors to assess military preventable deaths: subject matter experts provide valuable insights.

INTRODUCTION: Historically, there has been variability in the methods for determining preventable death within the US Department of Defense. Differences in methodologies partially explain variable preventable death rates ranging from 3% to 51%. The lack of standard review process likely misses opportunities for improvement in combat casualty care. This project identified recommended medical and non-medical factors necessary to (1) establish a comprehensive preventable death review process and (2) identify opportunities for improvement throughout the entire continuum of care. METHODS: This qualitative study used a modified rapid assessment process that includes the following steps: (1) identification and recruitment of US government subject matter experts (SMEs); (2) multiple cycles of data collection via key informant interviews and focus groups; (3) consolidation of information collected in these interviews; and (4) iterative analysis of data collected from interviews into common themes. Common themes identified from SME feedback were grouped into the following subject areas: (1) prehospital, (2) in-hospital and (3) forensic pathology. RESULTS: Medical recommendations for military preventable death reviews included the development, training, documentation, collection, analysis and reporting of the implementation of the Tactical Combat Casualty Care Guidelines, Joint Trauma System Clinical Practice Guidelines and National Association of Medical Examiners autopsy standards. Non-medical recommendations included training, improved documentation, data collection and analysis of non-medical factors needed to understand how these factors impact optimal medical care. CONCLUSIONS: In the operational environment, medical care must be considered in the context of non-medical factors. For a comprehensive preventable death review process to be sustainable in the military health system, the process must be based on an appropriate conceptual framework implemented consistently across all military services.

Hyperbaric oxygen therapy and the eye.

Hyperbaric oxygen therapy (HBOT) is a primary or adjunctive therapy for a variety of medical disorders including some involving the eye. This paper is the first comprehensive review of HBOT for ocular indications. The authors recommend the following as ocular indications for HBOT: decompression sickness or arterial gas embolism with visual signs or symptoms, central retinal artery occlusion, ocular and periocular gas gangrene, cerebro-rhino-orbital mucormycosis, periocular necrotizing fasciitis, carbon monoxide poisoning with visual sequelae, radiation optic neuropathy, radiation or mitomycin C-induced scleral necrosis, and periorbital reconstructive surgery. Other ocular disorders that may benefit from HBOT include selected cases of ischemic optic neuropathy, ischemic central retinal vein occlusion, branch retinal artery occlusion with central vision loss, ischemic branch retinal vein occlusion, cystoid macular edema associated with retinal venous occlusion, post-surgical inflammation, or intrinsic inflammatory disorders, periocular brown recluse spider envenomation, ocular quinine toxicity, Purtscher's retinopathy, radiation retinopathy, anterior segment ischemia, retinal detachment in sickle cell disease, refractory actinomycotiC lacrimal canaliculitis, pyoderma gangrenosum of the orbit and refractory pseudomonas keratitis. Visual function should be monitored as clinically indicated before, during, and after therapy when HBOT is undertaken to treat vision loss. Visual acuity alone is not an adequate measure of visual function to monitor the efficacy of HBOT in this setting. Ocular examinations should also include automated perimetry to evaluate the central 30 degrees of visual field at appropriate intervals. Interpretation of the literature on the efficacy of HBOT in treating ocular disorders is complicated by several factors: frequent failure to include visual field examination as an outcome measure, failure to adequately address the interval from symptom onset to initiation of HBOT, and lack of evidence for optimal treatment regimens for essentially all ocular indications. Because some ocular disorders require rapid administration of HBOT to restore vision, patients with acute vision loss should be considered emergent when they present. Visual acuity should be checked immediately, including vision with pinhole correction. If the patient meets the criteria for emergent HBOT outlined in the paper, normobaric oxygen should be started at the highest inspired oxygen fraction possible until arrangements can be made for HBOT.

Orbital hemorrhage following face-mask barotrauma.

A 41-yr-old female recreational diver suffered an orbital hemorrhage following face-mask barotrauma This case illustrates the potential for significant orbital injury to occur as a result of face-mask barotrauma Barotraumatic orbital hemorrhage is an unusual disorder, but recognition of this entity is important for diving physicians. The signs and symptoms should not be mistaken for decompression sickness or arterial gas embolism. Patients with barotraumatic orbital hemorrhage require emergency referral to an ophthalmologist so that potentially vision-threatening ocular complications may be identified and treated. Barotrauma may result in several different types of cranial neuropathies and should be recognized as another possible cause for neurologic deficits following a dive.

Tactical medicine training for SEAL mission commanders.

The Tactical Combat Casualty Care (TCCC) project initiated by the Naval Special Warfare Command and continued by the U.S. Special Operations Command has developed a new set of combat trauma care guidelines that seek to combine good medical care with good small-unit tactics. The principles of care recommended in TCCC have gained increasing acceptance throughout the Department of Defense in the 4 years since their publication, and increasing numbers of combat medical personnel and military physicians have been trained in this concept. Because casualty scenarios in small-unit operations typically present tactical as well as medical problems, however, it has become apparent that a customized version of this course suitable for small-unit mission commanders is a necessary addition to the program. This paper describes the development of a course in tactical medicine for SEAL mission commanders and its transition into use in the Naval Special Warfare community.

The U.S. Navy decompression computer.

The U.S. Navy has recently approved the Cochran NAVY decompression computer (DC) for use in Naval Special Warfare diving. This action represents the first approval of a diver-worn DC for use in the U.S. Navy. This paper reviews the development and testing of both the decompression algorithm and the hardware chosen for the Navy's DC. The decompression software in the Cochran NAVY is the VVAL 18 algorithm developed at the Navy Experimental Diving Unit (NEDU) by Captain Ed Thalmann. A discussion of the relative conservatism of the VVAL18 algorithm in comparison to the U.S. Navy Standard Air Tables and the basis for the differences between the two is provided. The initial guidelines establishing DC diving practice for the Navy SEAL community are outlined as are plans for future research efforts in U.S. Navy DC diving.

Screening for oxygen sensitivity in U.S. Navy combat swimmers.

The United States Naval Special Warfare Community uses oxygen tolerance testing to screen Navy combat swimmer candidates for sensitivity to the toxic effects of hyperbaric oxygen (HBO2). Between 1976 and 1997, 6,250 oxygen-tolerance tests were performed at the Naval Special Warfare Center and Naval Special Warfare Group One. Our review of these data found only six episodes of O2 toxicity for an incidence of 0.096%, an incidence considerably lower than the rate of 1.9% reported in an earlier review using data from the Naval Safety Center. Additionally, we reviewed data from the Naval Safety Center from 1986 to 1997 and found only one episode of O2 toxicity among 157,930 LAR V dives. Many factors other than individual sensitivity to HBO2 may contribute to the occurrence of O2 toxicity episodes during combat swimmer operations. The authors conclude that O2 tolerance testing of U. S. Navy SEAL candidates is not a useful screening test and recommend discontinuation of this test.

Hyperoxic myopia in a closed-circuit mixed-gas scuba diver.

A myopic shift occurred in a closed-circuit mixed-gas scuba diver using a 1.3 atm abs constant partial pressure of oxygen in a nitrogen-oxygen mix. This change was noticed after approximately 18 days of diving with a mean dive time of 4.04 h each day. The observed myopic shift was due to hyperoxic myopia, one sign of lenticular oxygen toxicity, and resolved over a 1 mo. period after diving was completed. On a subsequent drive trip, a myopic shift was found in both the index diver as well as two other divers breathing the same gasmix on similar profiles. Diving communities should be aware of the risk of both lenticular and pulmonary oxygen toxicity when conducting intensive diving at oxygen partial pressures in the 1.3-1.6 atm abs range.

Infraorbital hypesthesia after maxillary sinus barotrauma.

We report a case of a diver who suffered an episode of maxillary sinus barotrauma that presented with decreased sensation over the cutaneous distribution of the infraorbital nerve after an ascent which produced facial pain and crepitus. This case illustrates a potential confusion between a decompression sickness etiology and a barotraumatic etiology for the observed sensory deficit. The clinical features of this case were most consistent with a barotraumatic etiology for the findings noted. The anatomy of the trigeminal nerve and previous reports of cranial nerve deficits following barotrauma are reviewed.

Tactical combat casualty care in special operations.

U.S military medical personnel are currently trained to care for combat casualties using the principles taught in the Advanced Trauma Life Support (ATLS) course. The appropriateness of many of the measures taught in ATLS for the combat setting is unproven. A 2-year study to review this issue has been sponsored by the United States Special Operations Command. This paper presents the results of that study. We will review some of the factors that must be considered in caring for wounded patients on the battlefield with an emphasis on the Special Operations environment. A basic management protocol is proposed that organizes combat casualty care into three phases and suggests appropriate measures for each phase. A scenario-based approach is needed to plan in more detail for casualties on specific Special Operations missions, and several sample scenarios are presented and discussed.

Preliminary results of photorefractive keratectomy in active-duty United States Navy personnel.

PURPOSE: To evaluate the safety, efficacy, and quality of vision after photorefractive keratectomy (PRK) in active-duty military personnel. METHODS: Photorefractive keratectomy (6.0-mm ablation zone) was performed on 30 navy/marine personnel(-2.00 to -5.50 diopters [D]; mean, -3.35 D). Glare disability was assessed with a patient questionnaire and measurements of intraocular light scatter and near contrast acuity with glare. RESULTS: At 1 year, all 30 patients had 20/20 or better uncorrected visual acuity with no loss of best-corrected vision. By cycloplegic refraction, 53% (16/30) of patients were within +/- 0.50 D of emmetropia and 87% (26/30) were within +/- 1.00 D. The refraction (mean +/- standard deviation) was +0.45 +/- 0.56 D (range, -1.00 to 1.63 D). Four patients (13%) had an overcorrection of more than 1 D. Glare testing in the early (1 month) postoperative period demonstrated increased intraocular light scatter (P<0.01) and reduced contrast acuity (with and without glare, (P<0.01). These glare measurements statistically returned to preoperative levels by 3 months (undilated) and 12 months (dilated) postoperatively. Two patients reported moderate to severe visual symptoms (glare, halo, night vision) worsened by PRK. One patient had a decrease in the quality of night vision severe enough to decline treatment in the fellow eye. Intraocular light scatter was increased significantly (>2S D) in this patient after the procedure. CONCLUSIONS: Photorefractive keratectomy reduced myopia and improved the uncorrected vision acuity of all patients in this study. Refinement of the ablation algorithm is needed to decrease the incidence of hyperopia. Glare disability appears to be a transient event after PRK. However, a prolonged reduction in the quality of vision at night was observed in one patient and requires further study.

Diving and hyperbaric ophthalmology.

Exposure of the human body to ambient pressures greater than that at sea level may result in various disorders, some of which have ocular manifestations. Additionally, some eye disorders and postoperative states may be adversely affected by the underwater environment or other hyperbaric exposures. The prevalence of recreational, military, and commercial diving, as well as the medical use of hyperbaric oxygen therapy, requires that ophthalmologists be familiar with the effects of the hyperbaric environment on the normal and diseased eye. The ophthalmology and diving medical literatures were surveyed for publications relating to the ophthalmic aspects of diving and hyperbaric exposures. Underwater optics, underwater refractive correction, and ophthalmic aspects of a fitness-to-dive evaluation are summarized. The evaluation and management of ocular manifestations of decompression sickness and arterial gas embolism are reviewed and guidelines for diving after ocular surgery are proposed.

Altitude retinopathy on Mount Everest, 1989.

The authors studied prospectively the incidence of and risk factors for high altitude retinal hemorrhages among 14 members of the 1989 American Everest Expedition. All subjects had comprehensive eye examinations and fundus photography performed at sea level before the expedition and again at the Mt. Everest Base Camp after 6 weeks of exposure to altitudes between 5300 and 8200 meters. Asymptomatic intraretinal hemorrhages were found in five eyes of four climbers. An additional eye of one of these climbers had a central retinal vein occlusion with vitreous hemorrhage, which reduced visual acuity to counting fingers. Higher baseline intraocular pressure and use of nonsteroidal anti-inflammatory drugs were found to be significant risk factors for development of altitude retinopathy.

Decompression sickness presenting as optic neuropathy.

Decompression sickness (DCS) is a systemic disorder caused by an abrupt decrease in the ambient atmospheric pressure to which an individual is exposed. A previously healthy 23-year-old male parachutist developed optic neuropathy after a series of multiple repeated hypobaric exposures; his symptoms improved promptly with recompression and hyperbaric oxygen therapy. We believe this to be the first reported case of DCS presenting as optic neuropathy.

Visual reaction time performance preceding CNS oxygen toxicity.

The visual reaction time performance of divers experiencing CNS oxygen toxicity was assessed during the development of closed-circuit 100% oxygen breathing diving schedules at the U.S. Navy Experimental Diving Unit. Divers repeatedly performed the visual reaction time test of the Performance Measurement System (PMS) during multiple excursion dives. Each diver wore a Draeger LAR V UBA and performed moderate work on an underwater bicycle ergometer while engaged in the reaction time test. A single subject, repeated measures design was used. Six divers experienced 7 episodes of CNS oxygen toxicity while engaged in the visual reaction time test. Two episodes were preceded by a slowing and increase in variability of reaction time. Five episodes were not preceded by changes in reaction time performance. Other objective and subjective symptoms of toxicity experienced by the divers did not appear to be correlated with reaction time performance. Thus, the PMS visual reaction time test was not reliable method of detecting CNS oxygen toxicity in this study.

Progressive ulnar palsy as a late complication of decompression sickness.

We report an unusual case of decompression sickness in which a progressive ulnar palsy developed 22 days after the onset of neurological decompression sickness. The initial symptoms of numbness and paresthesias of the hand were treated with recompression therapy, resulting in only partial relief. The patient subsequently developed weakness of the left hand, which increased in severity until the institution of repeated daily hyperbaric oxygen treatments. A total of seven treatments resulted in partial resolution of the patient's signs and symptoms. Recovery was complete within four months.

A blitz of bends: decompression sickness in four students after hypobaric chamber training.

This paper reports three cases of type II and one case of type I decompression sickness occurring in a group of nine vigorously active US Army parachutists who took a hypobaric chamber HALO (high altitude-low opening) training flight to a maximum altitude of 9,908.5 m (32,500 ft). After the cases of decompression sickness were diagnosed and treated, the aviator mask regulators were checked and found to be functioning properly; the oxygen supply was analyzed and found to be pure. All cases fully recovered after treatment on US Navy Diving Table 6 and have returned to full military duty. This HALO training profile is not in use with either the US Navy or the US Air Force and should probably be considered unsafe for future use in training.