Bmj Military Health最新文献

Introduction: Administering supplemental oxygen is a standard of care for trauma casualties to minimise the deleterious effects of hypoxaemia. Forward deployment of oxygen using pressurised cylinders is challenging, for example, logistics (weight and finite resource) and environmental risk (fire and explosion). Oxygen concentrators may overcome these challenges. Although previous studies successfully demonstrated fractional inspired oxygen (FiO₂) >0.8 using oxygen concentrators and ventilators, the systems did not fulfil the size, weight and power requirements of agile military medical units. This study evaluated whether a modular system of commercially available clinical devices could supply high FiO₂ to either ventilated or spontaneously breathing casualties.

Methods: As a proof of principle, we configured an Inogen One G5 oxygen concentrator, Ventway Sparrow ventilator and Wenoll rebreather system to ventilate a simulated lung (tidal volume 500 mL). Casualty oxygen consumption (gas withdrawal inspiratory limb) and carbon dioxide (CO₂) production (CO₂ added expiratory limb) were simulated (respiratory quotient of 0.7-0.8). Three circuit configurations were evaluated: open (supplementary oxygen introduced into air inlet of ventilator); semiclosed (ventilator replaces rebreather bag of Wenoll, oxygen connected to either ventilator or Wenoll); and semiclosed with reservoir tubing (addition of 'deadspace' tube between ventilator patient circuit and Wenoll). Data presented as mean and 95% reference range.

Results: There were modest increases in FiO₂ with increasing Inogen settings in 'open' configuration 0.23 (0.23-0.24) and 0.30 (0.28-0.32) (Inogen output 420 and 1260 mL/min, respectively). With the 'semiclosed' configuration and oxygen added directly into rebreather circuit, FiO₂ increased to 0.36 (0.36-0.37). The addition of the 'reservoir tubing' elevated FiO₂ to 0.78 (0.71-0.85). FiO₂ remained stable over a 4-hour evaluation period. Fractional inspired carbon dioxide CO₂ increased over time, reaching 0.005 after 170 (157-182) min.

Conclusion: Combining existing lightweight devices can deliver high (>0.8) FiO₂ and offers a potential solution for the forward deployment of oxygen without needing pressurised cylinders.

Introduction: Delivering balanced blood resuscitation at the point of injury remains a significant logistical challenge in prehospital trauma care. To inform optimal transfusion strategies in austere environments, we conducted a simulation-based study comparing the operational demands of three prehospital transfusion approaches.

Methods: Three doctor-paramedic teams (six clinicians) undertook a crossover simulation of traumatic haemorrhage, completing all three arms in random order: two units red-cells-in-plasma (RCP), two units red blood cells plus two units thawed fresh frozen plasma (RBC+FFP), and two units red cells plus two units lyophilised plasma (RBC+LyoP). Outcomes were flow time (defined as time from decision-to-transfuse to completion of transfusion of all units), touch time (hands-on time) and process burden (steps, equipment, checks, personnel), timed in real-time and verified on video. A postscenario questionnaire captured user perceptions.

Results: All scenarios were completed without missing data. RCP consistently required the least time and operational effort. Median flow times (min:s) were 06:31 (RCP), 12:20 (RBC+FFP) and 16:29 (RBC+LyoP) (p=0.019). Median touch times (min:s) were 02:31 (RCP), 05:21 (RBC+FFP) and 13:03 (RBC+LyoP) (p=0.017). Touch/flow ratios were lowest for RCP (0.39), indicating reduced cognitive and physical load. Standardised process mapping identified 26 steps for RCP versus 46 for RBC+FFP and 52 for RBC+LyoP, reflecting a single set-up and one repetition for RCP compared with multiple repetitions and added reconstitution steps for LyoP. Equipment (4, 10, 12), checks (8, 16, 16) and personnel required (2, 2, 3) followed the same efficiency gradient. Five of six participants rated RCP as optimal for the patient, and all six for the crew; LyoP was unanimously judged as the most demanding.

Conclusions: In a simulated trauma scenario, a combined RCP component was delivered more quickly and with substantially less process burden than separate components. These operational gains support combined-component strategies for prehospital haemorrhage resuscitation in both military and civilian settings.

Introduction: Polytrauma is often characterised by rhabdomyolysis, hyperkalaemia and renal failure, which is treated with acute haemodialysis. Transport and storage of dialysate are expensive and cumbersome and require space that may be unavailable in resource-limited scenarios. We examined a portable, powerless dialysate generator in a porcine model of continuous renal replacement therapy (CRRT).

Methods: Anaesthetised swine (n=12) underwent bilateral nephrectomy and placement of a haemodialysis catheter. Intravenous potassium and urea were infused, and animals received CRRT with either a dialysate solution prepared with tap water through a novel portable dialysate generator (PDG) or commercially available dialysate (CAD, NxStage). Both groups were dialysed with a NxStage System One through an in-line haemodialysis filter at typical flow rates. Blood samples were drawn hourly during 6 hours of CRRT.

Results: There were no differences in conductivity between PDG and CAD (p=0.31), as well as no detected arsenic, lead, mercury or free chlorine in the PDG dialysate produced. After 6 hours of CRRT, total effluent fluid was 10.09±0.18 L and 10.04±0.30 L in the PDG and CAD groups, respectively (p=0.89). Urea reduction ratio was similar in the two groups (p=0.39), as were serum levels of potassium (p=0.87). All animals survived until the end of CRRT.

Conclusions: A PDG machine using potable water created dialysate of similar efficacy as commercial prepackaged dialysate in a porcine CRRT model. The generated dialysate may obviate transport and storage of large quantities of dialysate in a resource-limited combat or natural disaster environments.

Introduction: Anterior cruciate ligament reconstruction (ACL reconstruction) and the subsequent return to military duty are important concerns for military personnel. This study aimed to evaluate the outcomes of ACL reconstruction and the rate of and factors influencing return to duty among military personnel.

Methods: A retrospective cross-sectional study of military personnel undergoing ACL reconstruction between 2010 and 2020, with at least 2 years of follow-up. Demographic data, injury and surgery details, activity at injury, Lachman test, Lysholm score, complications and return to military duty were recorded.

Results: We included 408 military personnel. Injuries mostly occurred during sports (76.5%), mainly football. Autologous hamstring tendon grafts were used in 79.2%. Meniscal injury was present in 54.9%, treated with repair or partial meniscectomy. Complications were infrequent, with 0.7% infection or graft re-rupture. Postoperative knee stability improved significantly, with 84.1% showing no anterior tibial translation. Over 90% achieved good or excellent Lysholm scores. Return to duty was achieved in 89.2%, with the majority returning to previous military duties; 8.8% had occupational reassignment due to physical limitations, and 2% were medically discharged. Most patients had a normal body mass index (BMI); return rates were lower in patients with BMI <18.5 or ≥30.

Conclusions: ACL reconstruction provides favourable functional and stability outcomes, resulting in high return-to-duty rates in military personnel. Extremes of BMI adversely impact return to duty, highlighting the need for tailored perioperative and rehabilitation strategies to optimise recovery and military readiness.

Obesity remains a significant public health concern with substantial implications for military readiness. Rising rates of overweight and obesity among service members challenge recruitment, retention and deployability. Although the military continues to screen and manage obesity, current body composition tools and policies often fail to capture true health risk or operational capability. This narrative review evaluates the prevalence and impact of obesity in the US military, critiques existing assessment methods and discusses recent policy updates across service branches. Particular attention is given to limitations of traditional metrics such as body mass index and circumference-based measures, as well as the potential of modern approaches to improve accuracy and effectiveness. Despite policy revisions, obesity remains the leading medical disqualifier for service and a major contributor to lost workdays, injuries and medical costs. Aligning body composition standards with scientific evidence and operational demands is essential for supporting readiness across modern defence forces.