Aviation, space, and environmental medicine最新文献

Purpose: This study was conducted to determine whether protans have slower reaction times to red lights than individuals with normal color vision and to identify whether protan reaction times increase differentially in a mildly hypoxic environment.

Methods: Simple reaction times (SRT) to a red light-emitting diode (LED) display were measured using the Psychomotor Vigilance Task (PVT) at ground (1293 ft/394 m), simulated 12,400-ft (3780-m) altitude, and 20 min after returning to ground. Subjects were 13 individuals with normal color vision (NCV), 12 with a deutan color vision defect, and 4 with a protan color vision defect.

Results: The mean reaction times increased by 8% with altitude and decreased after returning to ground for all groups. However, the reaction times of the protans were often faster than the NCV mean and never below the NCV 10(th) percentile. The only significant difference between color vision groups was the slowest mean reaction time of the NCV group was slower than both the pooled dichromats and pooled anomalous trichromats across all conditions by 23%. The number of lapses did not vary with altitude, but the dichromatic subjects had significantly fewer lapses than the trichromatic subjects across all conditions.

Conclusion: Although protans may be slower to respond to some red warning lights, this decrement in performance could not be demonstrated under the conditions of our experiment. Furthermore, the protan group's simple reaction times were not differentially affected by mild hypoxia. These results suggest that the red LEDs were sufficiently bright for these protan observers.

Background: Ejection neck safety remains a concern in military aviation with the growing use of helmet mounted displays (HMDs) worn for entire mission durations. The original USAF tensile neck injury criterion proposed by Carter et al. (4) is updated and an injury protection limit for tensile loading is presented to evaluate escape system and HMD safety.

Methods: An existent tensile neck injury criterion was updated through the addition of newer post mortem human subject (PMHS) tensile loading and injury data and the application of Survival Analysis to account for censoring in this data. The updated risk function was constructed with a combined human subject (N = 208) and PMHS (N = 22) data set.

Results: An updated AIS 3+ tensile neck injury criterion is proposed based upon human and PMHS data. This limit is significantly more conservative than the criterion proposed by Carter in 2000, yielding a 5% risk of AIS 3+ injury at a force of 1136 N as compared to a corresponding force of 1559 N.

Discussion: The inclusion of recent PMHS data into the original tensile neck injury criterion results in an injury protection limit that is significantly more conservative, as recent PMHS data is substantially less censored than the PMHS data included in the earlier criterion. The updated tensile risk function developed in this work is consistent with the tensile risk function published by the Federal Aviation Administration used as the basis for their neck injury criterion for side facing aircraft seats.

Background: Recent UK military operations in support of the fight against terrorism have resulted in UK military casualties. Movement of these casualties through the military medical chain requires a highly sophisticated aeromedical evacuation capability with worldwide reach. Recognition of the determinants of evacuation allows development to ensure optimal future configurations of military aeromedical evacuation services.

Methods: The database recording aeromedical evacuations undertaken by the Royal Air Force was searched to provide demographic and clinical data for evacuations between 1 April 2003 and 31 March 2010. Diagnoses leading to evacuation were categorized according to International Classification of Diseases codes.

Results: There were 21,477 medical evacuations undertaken. Analysis demonstrated 85.9% were for men and 86.5% were for military personnel, of whom 72.0% were in the army. The most common reasons for evacuation in military patients were musculoskeletal/connective tissue disorders (N = 9192; 50.0%), trauma (N = 1303; 7.1%), and mental health disorders (N = 1151; 6.3%). The most common reasons for evacuation in nonmilitary patients were musculoskeletal/connective tissue disorders (N = 734; 23.8%), genitourinary disorders (N = 325; 10.5%), and circulatory disorders (N = 255; 8.3%). Nontraumatic diagnoses were the determinants of evacuation in 92.9% of military and 95.1% of nonmilitary patients; 17.8% of trauma patients and 0.5% of nontrauma patients utilized high-dependency care.

Discussion: The UK aeromedical evacuation system must have the capacity to evacuate large numbers of patients with nontraumatic diagnoses, but also the flexibility to accommodate smaller, more variable numbers of higher dependency trauma patients. The military medical chain must continually review the differing requirements of civilian patients transferred within their aeromedical system.

Introduction: The prevalence, progression rates, and outcomes affecting aviator valvular heart disease have not been extensively studied.

Methods: The U.S. Air Force (USAF) School of Aerospace Medicine's Clinical Sciences Database was used to determine prevalence and progression rates for regurgitant valvular disease. A subset of the initial population was further evaluated for risk factors that increased the likelihood of progression. Descriptive statistical analysis, analysis of variance, and t-test calculations were completed.

Results: There were 8475 unique aviators with some degree of valvular regurgitation for an overall prevalence of 3.0%. The mitral and aortic valves were most likely to have mild and moderate or greater regurgitation, respectively. Progression rates from mild to moderate were 8% in the aortic valve, 2% in the mitral valve, and less than 1% in the pulmonic and tricuspid valves. Progression rates from moderate to severe were over 20% for both the mitral and aortic valves. The only risk factors correlating to progression of valvular disease were lower levels of high-density lipoproteins in the mitral and aortic valves and triglycerides in the mitral valve.

Discussion: In USAF aviators, progression rates for mild or greater aortic valve regurgitation and moderate or greater mitral valve regurgitation are significant and should be followed closely. Classic risk factors of age, tobacco use, elevated blood pressure, and hyperlipidemia have no association with increased risk of valvular progression or rate of progression. Study outcomes validate the current USAF policy for valvular heart disease in aviators.

Background: Hypobaric hypoxic exposures are associated with a number of risks, most notably decompression sickness and various ophthalmologic disorders, including high altitude retinopathy. Central serous chorioretinopathy (CSCR) is an idiopathic condition that typically affects young males and is associated with several comorbidities and medications; however, an association with hypoxia or high altitude has not been identified. We present a case of CSCR in an aviator following a simulated flight in a hypobaric chamber.

Case report: A 30-yr-old male U.S. Navy pilot presented with complaints of painless unilateral scotoma, micropsia, and blurred vision 1 h after completing a training exercise in a hypobaric chamber. A dilated fundoscopic examination, macular optical coherence tomography, and intravenous fluorescein angiography confirmed a diagnosis of CSCR. The patient was restricted from flying duty and observed for a period of 1 mo, after which point his symptoms spontaneously resolved and flight status was restored.

Discussion: Complaints of visual symptoms immediately following hypobaric exposure should primarily trigger suspicion of decompression sickness; however, once ruled out, patients should be referred to an eye specialist for detailed ocular examination. This case suggests a possible link between CSCR and hypobaric hypoxia as a topic of further investigation.

Objectives: This study was aimed at investigating the caries status of Chinese civilian pilots and the relationship between caries and oral health behaviors, including sugar intake, smoking, alcohol consumption, tooth brushing, and dental check-up attendance.

Methods: This cross-sectional investigation enrolled pilots from Shenzhen Airline. A questionnaire was used to collect general information and oral health behaviors. The Decayed, Missing, and Filled Teeth (DMFT) Index, International Caries Detection and Assessment System (ICDAS) II, caries prevalence, and rate of missing teeth were recorded via oral examination. Rank correlation was used to reveal the correlation between caries and oral health behavior.

Results: All of the pilots were men ages 21-58 yr (mean, 31.48 ± 7.20). In the caries group (CG), the frequency of tooth brushing and flossing was a little higher; more subjects had already given up smoking; more subjects had higher alcohol consumption; the sugar intake index (SII) was a little bit higher; and the last dental attendance time (LDAT) was shorter than that in the noncaries group (NCG). A total of 211 pilots (37.95%) had caries and 85 (15.29%) had missing teeth. The average DMFT was 2.19, while the mean ICDAS was 0.72. The frequency of sugary beverage consumption was negatively correlated with caries (r = -0.088), while a positive relationship was found between LDAT and caries (r = 0.094).

Conclusions: Chinese civilian pilots have relatively good oral hygiene behavior and dental health. A relationship was found between sugary beverage consumption/LDAT and caries.

Introduction: Flying after diving may increase decompression sickness risk (DCS), but strong evidence indicating minimum preflight surface intervals (PFSI) is missing.

Methods: On return flights after a diving week on a live-aboard, 32 divers were examined by in-flight echocardiography with the following protocol: 1) outgoing flight, no previous dive; 2) during the diving week; 3) before the return flight after a 24-h PFSI; and 4) during the return flight.

Results: All divers completed similar multiple repetitive dives during the diving week. All dives were equivalent as to inert gas load and gradient factor upon surfacing. No bubbles in the right heart were found in any diver during the outgoing flight or at the preflight control after a 24-h PFSI following the diving week. A significant increase in the number and grade of bubbles was observed during the return flight. However, bubbles were only observed in 6 of the 32 divers. These six divers were the same ones who developed bubbles after every dive.

Conclusions: Having observed a 24-h preflight interval, the majority of divers did not develop bubbles during altitude exposure; however, it is intriguing to note that the same subjects who developed significant amounts of bubbles after every dive showed equally significant bubble grades during in-flight echocardiography notwithstanding a correct PFSI. This indicates a possible higher susceptibility to bubble formation in certain individuals, who may need longer PFSI before altitude exposure after scuba diving.

Background: Prior reports have shown that decompression sickness (DCS) in scuba divers is accompanied by vascular endothelium damage attributed to gas emboli formation, resulting in capillary leak with hemoconcentration. The significance of serum albumin as a biomarker of vascular permeability in this condition has been insufficiently investigated. We studied whether there was a relationship between low serum albumin values on admission and the occurrence of neurological DCS.

Methods: Demographic, diving, and laboratory data of 52 randomly selected DCS divers were compared with those of 52 asymptomatic divers referred for inadequate decompression. The diagnostic performance of serum albumin in predicting neurological DCS was assessed.

Results: Both groups did not differ from the variables examined. Serum albumin was significantly lower in injured divers than in controls (38.7 ± 3 g · L(-1) vs. 41 ± 2.9 g · L(-1)). At a cut-off value of 35.2 g · L(-1), we found a specificity of 98% (95% CI 90-100) and a sensitivity of 16% (95% CI 7-28) for the prediction of neurological DCS development.

Conclusion: Our findings suggest that hypoalbuminemia at initial presentation, albeit rare, accurately predicts the occurrence of neurological DCS in scuba divers. The prognostic value of this biomarker and the potential beneficial role of albumin infusion in more severe cases remain to be investigated.