INTRODUCTION: The present study evaluated the efficacy of the nine-step inflation-deflation tympanometric test for predicting recurrence of middle ear barotrauma.METHODS: Student pilots who were diagnosed with middle ear barotrauma from October 2010 to April 2011 were enrolled. The grade of barotrauma was assigned using Teed’s classification. All subjects underwent tympanometry and nine-step inflation-deflation testing at first visit and after improvement. Recurrence was monitored for 2 wk after they resumed flight. The relationships among the recurrence of middle ear barotrauma, the grade and duration of disease, and tympanometric and nine-step test results were evaluated.RESULTS: There were 35 cases enrolled. According to Teed’s classification, 16 cases were Grade 0 (45.7%) and 11 cases were Grade I (31.4%). Grade III was shown in seven cases (20.0%) and one subject was Grade IV (2.9%). The mean duration of illness was 5.9 d. In the initial 9-step tests, 29 subjects (85.3%) failed to pass the entire test. On follow-up tests, eight cases (22.9%) failed. Seven pilots (20.0%) showed recurrent middle ear barotrauma after resumed flight. All of the cases with recurrence failed the follow-up nine-step tests. The nine-step test showed high sensitivity and specificity values for predicting recurrence. A clear correlation was observed between recurrence and nine-step test results.DISCUSSION: The nine-step inflation-deflation test provides useful information about Eustachian tube function. The nine-step test can be useful to reduce the risk of recurrence of middle ear barotrauma in pilots.Sohn JH. Recurrent middle ear barotrauma in student pilots. Aerosp Med Hum Perform. 2019; 90(8):681–687.

INTRODUCTION: Changes in gravity or body position provoke changes in hydrostatic pressure in the arterial system and in venous return. Potential asymmetries between left (Q_LV) and right ventricular (Q_RV) cardiac output during transient gravity changes were investigated. It was hypothesized that blood volume is temporarily stored in the pulmonary vessels, with amount and duration depending on the level and directions of gravity.METHODS: Eight healthy, male subjects (32 ± 3 yr, 182 ± 7 cm, 82 ± 6 kg) were tested on a tilt seat (TS), in a long arm human centrifuge (laHC), and during parabolic flights (PF). The gravitational changes during PF were reconstructed by changing gravity in a laHC and different body positions on a TS. All participants were tested in the seated, resting position. Heart rate and blood pressure were recorded continuously and Q_LV was calculated, applying the Modelflow Algorithm. Gas exchange was measured breath-by-breath. Q_RV was calculated from these data according to the Fick Principle. Four sequences were superimposed and analyzed by ANOVA with the factors Time, Ventricle (Q_RV, Q_LV), and Mode (TS, PF, laHC).RESULTS: After reductions in gravity Q_RV and Q_LV were transiently desynchronized. ANOVA showed no main effect for Mode, but significant changes were found for Time and Ventricle and all interactions.DISCUSSION: Phases of reduced gravity seem to lead to transiently increased storage of blood volume inside the pulmonary vascular system. A more detailed understanding of these mechanisms might help to describe the compliance of the pulmonary vascular system in diseases of the pulmonary circulation.Hoffmann U, Koschate J, Appell Coriolano H-J, Drescher U, Thieschäfer L, Dumitrescu D, Werner A. Adaptation of systemic and pulmonary circulation to acute changes in gravity and body position. Aerosp Med Hum Perform. 2019; 90(8):688–695.

BACKGROUND: Establishing animal models of ear barotrauma (EB) to provide evaluation criteria for Eustachian tube dysfunction.METHODS: Using expansive sponges, 70 rabbits’ right pharyngeal openings of the auditory tubes were blocked to cause dysfunction in the right Eustachian tubes. The right tympanic cavities of 65 rabbits were the Model Group (Subgroups 1–13) and these rabbits’ left tympanic cavities were the Nonblockage Group. Hypobaric chamber tests (HCTs) at various vertical speeds (100 m · s⁻¹, 75 m · s⁻¹, 50 m · s⁻¹, and 15 m · s⁻¹) and altitudes (13,123 ft and 6562 ft) were conducted. The remaining five rabbits’ right tympanic cavities were the Control Group and no HCTs were conducted. After HCTs, observations were made on rabbits’ behavioral changes, oto-endoscope and tympanometry results, and pathological changes of the tympanic mucosae.RESULTS: 1) Rabbits in Subgroups 1–12 demonstrated EB, while Subgroup 13 and the Control Group did not. 2) Histopathology showed EB caused by rapid ascent/descent at 100 m · s⁻¹ was more severe than that of 75 m · s⁻¹ and 50 m · s⁻¹ (P < 0.01), and that there were no significant differences in EB caused by rapid ascent/descent at 75 m · s⁻¹ and 50 m · s⁻¹ (P > 0.05). There were no significant differences in pathological injuries at the altitudes of 6562 ft and 13,123 ft (P > 0.05). 3) Based on tympanic membrane structures, tympanometry, and histopathological results, rabbits’ EB can be classified into mild, moderate, and severe.DISCUSSION: EB’s dynamic models could be established through HCTs on rabbits with Eustachian tube dysfunction.Wang B, Xu X, Lin J, Jin Z. Dynamic rabbit model of ear barotrauma. Aerosp Med Hum Perform. 2019; 90(8):696–702.

BACKGROUND: Raised blood pressure (BP) is a risk factor for cardiovascular disease, which is a common cause of sudden in-flight incapacitation among pilots. Prevalence of hypertension (HT) among pilots as per new criteria is largely unknown. This study aims to understand the prevalence of hypertension and obesity in civil aviation pilots and their correlation.METHODS: Enrolled were 1185 civilian pilots reporting for medical evaluation to a regulatory medical establishment in India. Their height, weight, and blood pressure (BP) were measured. Pilots were categorized as hypertensive or normotensive as per JNC VIII criteria and hypertensive, having elevated BP, or normotensive as per new ACC/AHA criteria of 2017. Data were analyzed for prevalence of obesity and overweight as per both WHO and Asia Pacific criteria. Results were analyzed using SPSS version 17.RESULTS: Prevalence of hypertension was 4.1%. Maximum hypertensives were in the 26–35 yr age group. Under the new ACC/AHA guidelines, prevalence of HT was 18.7%. Prevalences of overweight and obesity as per WHO criteria were 39% and 7.3% and as per Asia Pacific guidelines were 23.3% and 46.3%, respectively. As BMI increased above 23, risk of developing hypertension or white coat hypertension as per JNC VIII criteria increased by 6.86 times (OR 6.86, 95% CI 0.9–52.58).CONCLUSIONS: Prevalence of HT rose from 4.1% to an alarmingly high 18.7% when new criteria were applied. Prevalence of obesity was 7.3% but increased to 46.3% when Asia Pacific guidelines were applied. Risk of hypertension increased as BMI increased above 23 kg · m⁻².Bhat KG, Verma N, Pant P, Marwaha MPS. Hypertension and obesity among civil aviation pilots. Aerosp Med Hum Perform. 2019; 90(8):703–708.

INTRODUCTION: Exposure to excess manganese (Mn) can cause multiple toxicological outcomes in humans, most notably neurotoxicity. Ample epidemiological evidence suggests that chronic, low-level exposure causes subclinical cognitive effects. Because NASA astronauts will be exposed to Mars regolith, Spacecraft Maximum Allowable Concentrations (SMACs) were developed following an extensive literature review.METHODS: Multiple databases were searched for information relevant to derivation of Mn SMAC values. An additional search for Mars dust data was performed. Risk assessment approaches were applied, including adjustments for space-relevant susceptibility to Mn effects, to develop limits for 1-h to 1000-d exposures. Rover data informed the assessment and enabled calculation of allowable total dust exposure based on Mn content.RESULTS: Over 400 relevant sources were identified. Applicability of exposure characteristics and data collection methods influenced key study choice. SMACs ranging from 3 mg · m⁻³ (1 h) – 0.0079 mg · m⁻³ (1000 d) were set to protect primarily against neurocognitive and respiratory effects. Considering 0.38 wt% total Mn presence in the dust, maximum recommended total dust exposure should not exceed 790 mg · m⁻³ (1 h) – 2 mg · m⁻³ (1000 d).DISCUSSION: This literature review allowed for identification of relevant studies to inform SMAC development. Manganese is one of several components to consider when developing an appropriate total dust limit for Martian dust; other dust elements may alter Mn bioavailability. Mission-specific activities may require alteration of assumptions regarding Mn dust concentration and exposure duration. However, based on expected toxicity of particulate matter itself, the acute SMACs are protective, even with transient exposure during activities that could produce higher concentrations.Romoser AA, Ryder VE, McCoy JT. Spacecraft maximum allowable concentrations for manganese compounds in Mars dust. Aerosp Med Hum Perform. 2019; 90(8):709–719.

INTRODUCTION: The incidence of hypoxia-like symptoms in military aviators is on the rise. Cases can be related to On-Board Oxygen Generating System (OBOGS) malfunction, air contamination, loss of cabin pressurization, hyperventilation, or a combination of these issues simultaneously. Normobaric hypoxia training in tactical fighter simulations has been conducted in the Finnish Air Force since 2008. This training helps aviators to recognize their individual hypoxia symptoms and refreshes hypoxia emergency procedures in a realistic cockpit.METHODS: A flight mission included three set-ups and a return to base (RTB) after the third set-up. In a tactical Hawk simulator, different concentrations of oxygen were used (8%, 7%, and 6% oxygen in nitrogen) to create normobaric hypoxia exposures. During the RTB, the flight instructor evaluated the subjects’ flight performance (N = 16) in order to estimate cognitive functions after hypoxia. A control flight was evaluated before or after the flight with normobaric hypoxia exposure.RESULTS: Instrumental flight rule performance during RTB decreased significantly from 4.81 to 3.63 after normobaric hypoxia and emergency procedures. Some pilots reported fatigue, headache, memory problems, and cognitive impairment as adverse effects up to 12 h after normobaric hypoxia training.DISCUSSION: Hypoxia has a significant effect on flight performance during RTB, even 10 min after hypoxia emergency procedures. Since 100% oxygen was used as emergency oxygen, as in a real aircraft, the oxygen paradox may decrease flight performance. Hypoxia training in tactical fighter simulations provides an opportunity for pilots to also understand the effects of the “hypoxia hangover” on their flight performance.Varis N, Parkkola KI, Leino TK. Hypoxia hangover and flight performance after normobaric hypoxia exposure in a Hawk simulator. Aerosp Med Hum Perform. 2019; 90(8):720–724.

INTRODUCTION: Aerospace medicine training is often difficult to obtain outside of military education streams. Undergraduate medical trainees and residents may undertake training opportunities, but often have trouble locating programs and/or receiving credit for their experiences and learning. In many countries, no formal aerospace medicine training program or pathway exists and trainees must search out opportunities on their own. Canada is used as an example of a country which, until recently, had no defined civilian aerospace medicine training program or credentialing pathway. Recent development of a Diploma in Aerospace Medicine certified by the Royal College of Physicians and Surgeons now outlines a series of competencies for trainees and medical professionals seeking advancement in aerospace medicine. Growth of the aviation and aerospace fields will require more training opportunities and more aerospace medicine professionals to support the increased number of aviators and the spacefaring population. This will be particularly important as commercial space companies develop the potential for civilian spaceflight. While few opportunities exist for training, we highlight the major aerospace medicine training opportunities that have been recently available to Canadians. It is our hope that highlighting previous and current opportunities may aid in the development of a formal training program leading to certification in aerospace medicine for Canadians and act as an example for other nations.Sirek A, Samoil K, Harrison MF. Space medicine training in Canada. Aerosp Med Hum Perform. 2019; 90(8):725–729.

BACKGROUND: For over 30 yr the global medical community has attempted to define the acceptable cardiovascular risk in pilots. This challenge is compounded by the ever-changing technological and medical landscape of air travel. We aimed to review the existing literature on estimating the risk of pilot cardiovascular incapacitation and determine if the current guidelines are founded in the best available evidence.METHODS: A detailed review of the guidelines and literature that supports them was completed. Relevant articles were identified by review of the source literature of the guidelines and the references of these source documents. All articles referenced were reviewed in full by both authors. Data that informed the existing recommendations were reviewed and compared to available modern data. The results of these findings were incorporated into a formula that allows for the calculation of acceptable pilot cardiovascular risk given any operator-determined set of variables.RESULTS: Among the evidence that informs current guidelines, there exists a need for further updating. A number of assumptions have been made in creating guidelines and these may no longer reflect the current technological or medical aviation environment. Incorporating the identified variables into a formula allows for the calculation of acceptable cardiovascular risk. This formula was tested using past data and reproduced existing results.DISCUSSION: Current guidelines for pilot cardiovascular risk assessment require review by the international aviation medical community. We propose a novel formula that may serve as a template for future guidelines and may be adapted as aviation technology and health data evolve.Mulloy A, Wielgosz A. Cardiovascular risk assessment in pilots. Aerosp Med Hum Perform. 2019; 90(8):730–734.

INTRODUCTION: Due to the risk of hypoglycemia-related incapacitation, diabetic pilots requiring insulin are assessed as unfit according to the International Civil Aviation Organization and most national authorities. Some authorities, such as those from Canada, the United Kingdom, and the United States, permit selected insulin-treated pilots (ITDM-pilots) to fly subject to a protocol requiring pre- and in-flight capillary glucose measurements to show safe levels (>100–<300 mg · dl⁻¹). Critics of such permission question the practicability of these in-flight measurements and whether clinically desired glycemic targets can be achieved while keeping glucose levels in the safe range. Subcutaneous continuous glucose monitoring (CGM) has recently been approved by the FDA as a stand-alone method to provide accurate glucose levels and treatment decision guidance in patients. This commentary considers that use of CGM by ITDM pilots facilitates practicability and recording of in-flight glucose measurements and facilitates achievement of clinically desired glycemic targets without increasing hypoglycemia risks.Strollo F, Simons R, Mambro A, Strollo G, Gentile S. Continuous glucose monitoring for in-flight measurement of glucose levels of insulin-treated pilots. Aerosp Med Hum Perform. 2019; 90(8):735–737.

Gear M. You’re the flight surgeon: pituitary adenoma. Aerosp Med Hum Perform. 2019; 90(8):740–743.