Aviation, space, and environmental medicine最新文献

Introduction: Some commercial spaceflight participants (SFPs) may have medical conditions that require implanted medical devices (IMDs), such as cardiac pacemakers, defibrillators, insulin pumps, or similar electronic devices. The effect of space radiation on the function of IMDs is unknown. This review will identify known effects of terrestrial and aviation electromagnetic interference (EMI) and radiation on IMDs in order to provide insight into the potential effects of radiation exposures in the space environment.

Methods: A systematic literature review was conducted on available literature on human studies involving the effects of EMI as well as diagnostic and therapeutic radiation on IMDs.

Results: The literature review identified potential transient effects from EMI and diagnostic radiation levels as low as 10 mGy on IMDs. High-energy, therapeutic, ionizing radiation can cause more permanent device malfunctions at doses as low as 40 mGy. Radiation doses from suborbital flight altitudes and durations are anticipated to be less than those experienced during an average round-trip, cross-country airline flight and are unlikely to result in significant detriment, though longer, orbital flights may expose SFPs to doses potentially harmful to IMD function.

Discussion: Individuals with IMDs should experience few, if any, radiation-related device malfunctions during suborbital flight, but could have problems with radiation exposures associated with longer, orbital flights.

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: Radiotherapy is the standard and most effective treatment for nasopharyngeal carcinoma (NPC) in its early stages. However, its application in fighter pilots returning to flying duties with NPC has not been previously reported, presumably due to post-radiotherapeutic complications.

Case report: A 36-yr-old male fighter pilot had a painless mass in the left neck for 5 mo. Pathological diagnosis demonstrated nonkeratinizing squamous cell carcinoma in the left nasopharynx which had metastasized to lymph nodes in the left side of the neck. He was diagnosed and staged with NPC (T1N2M0) before treatment with radiotherapy and adjuvant chemotherapy. The patient suffered from catarrhal otitis media and xerostomia after 3 mo of radiotherapy, but these symptoms resolved. After a total of 8 mo of radiotherapy, he was in remission with no evidence of tumor recurrence or metastasis. He had normal Eustachian tube, hearing, and vestibular function before and after hypobaric chamber testing and passed all flight-related physical examinations. Consequently, he was granted a medical waiver and returned to flying status in two-seat fighter aircraft, flying for 53 h in a 12-mo period. After passing all flight-related tests again, he was then allowed to fly in single-seat aircraft. At the time of submission of this article, he has flown for 147 h and remained on flying status for 26 mo. He will be monitored annually for long-term effects of radiotherapy and/or disease recurrence.

Conclusions: Fighter pilots with NPC may be safely considered for medical waiver with appropriate monitoring after successful treatment.