Comparison of the effects of ketamine and morphine on performance of representative military tasks.

BACKGROUND: When providing care under combat or hostile conditions, it may be necessary for a casualty to remain engaged in military tasks after being wounded. Prehospital care under other remote, austere conditions may be similar, whereby an individual may be forced to continue purposeful actions despite traumatic injury. Given the adverse side-effect profile of intramuscular (i.m.) morphine, alternative analgesics and routes of administration are of interest. Ketamine may be of value in this capacity. OBJECTIVES: To delineate performance decrements in basic soldier tasks comparing the effects of the standard battlefield analgesic (10 mg i.m. morphine) with 25 mg i.m. ketamine. METHODS: Representative military skills and risk propensity were tested in 48 healthy volunteers without pain stimuli in a double-blind, placebo-controlled, crossover design. RESULTS: Overall, participants reported more symptoms associated with ketamine vs. morphine and placebo, chiefly dizziness, poor concentration, and feelings of happiness. Performance decrements on ketamine, when present, manifested as slower performance times rather than procedural errors. CONCLUSIONS: Participants were more symptomatic with ketamine, yet the soldier skills were largely resistant to performance decrements, suggesting that a trained task skill (autonomous phase) remains somewhat resilient to the drugged state at this dosage. The performance decrements with ketamine may represent the subjects' adoption of a cautious posture, as suggested by risk propensity testing whereby the subject is aware of impairment, trading speed for preservation of task accuracy. These results will help to inform the casualty care community regarding appropriate use of ketamine as an alternative or opioid-sparing battlefield analgesic.

Longitudinal Changes in the Body Mass Index of British Army Pilots.

INTRODUCTION: Aircraft are manufactured according to design parameters that must account for the size and physical characteristics of the pilot. While cockpit dimensions, seats, restraints, and related components do not change substantially over the airframe lifecycle, it is conceivable that the occupant may, even if initially well-suited. This investigation focused on longitudinal body mass index (BMI) changes within a cohort of British Army Air Corps pilots.METHODS: The study was a retrospective examination of electronic medical record data to assess longitudinal change within a representative cohort of Army pilots. Voluntary subjects were assigned unique subject numbers matched with individual electronic medical record data. Subject's age, service length, height, weight, and BMI were extracted from routine historical aviation medical exams.RESULTS: Among 106 British Army Air Corps pilots, the mean age was 35.3 yr (SD = 7.4) with average length of service as a pilot of 9.0 yr (SD = 5.2). Within the observed cohort, the mean change in individual weight over time was an increase of 4.6 kg (SD = 7.3). Height remained relatively stable with a mean increase of 0.6 cm (SD = 1.9). Given the increase in weight, BMI was noted to increase longitudinally with a mean of 1.3 kg · m-2 (SD = 2.4).DISCUSSION: British Army pilots experience increases in BMI over time much like the general population. Results of this study serve to inform future policy related to the body composition of aviation applicants, the retention of previously qualified pilots, and the safety concerns of crashworthiness design specifications.Porter WD, Wilde GD, Jeffery NP, Walters PL, Eke AJ, Bushby AJR, Adams MS, Gaydos SJ. Longitudinal changes in the body mass index of British Army pilots. Aerosp Med Hum Perform. 2024; 95(2):118-122.

Hypoxic hypoxia at moderate altitudes: review of the state of the science.

Unpressurized aircraft routinely operate at altitudes where hypoxia may be of concern. A systematic literature review was conducted regarding hypoxic impairment, including mental functions, sensory deficits, and other pertinent research findings that may affect aviation-related duties at moderate altitude (8000 to 15,000 ft/2438 to 4572 m). The results of this review suggest that cognitive and psychomotor deficits may include learning, reaction time, decision-making, and certain types of memory. However, results are difficult to quantify and reliably reproduce. Inconsistency of results may be related to the subtlety of deficits compared to high altitude, differences among individual compensatory mechanisms, variation in methodology or sensitivity of metrics, presence or absence of exercise, heterogeneous neuronal central nervous system (CNS) response, and interindividual variation. Literature regarding hypoxic visual decrements is more consistent. Rod photoreceptors are more susceptible to hypoxia; visual degradation has been demonstrated at 4000 to 5000 ft (1219 to 1524 m) under scotopic and 10,000 ft (3048 m) under photopic conditions. Augmented night vision goggle resolution demonstrates more resilience to mild hypoxic effects than the unaided eye under starlight conditions. Hypocapnia enhances visual sensitivity and contrast discrimination. Hyperventilation with resulting respiratory alkalosis and cerebral vasoconstriction may confound both cognitive/ psychomotor and visual experimental results. Future research should include augmentation of validated neuropsychological metrics (surrogate investigational end points) with actual flight metrics, investigation of mixed gas formulations, contribution of hypocapnic vasoconstrictive effects on hypoxic performance, and further investigation into cellular- and systems-level approaches for heterogeneous CNS response. Research is also required into the contribution of mild-moderate hypoxia in human factors- and spatial disorientation-related mishaps.