Grounding of Pilots: Medical Reasons and Recommendations for Prevention.

BACKGROUND: This article presents the results of an EASA-commissioned study aimed at analyzing the medical causes of grounding of a broad European pilot population and recommending measures to reduce the risk of in-flight incapacitation in commercial air transport pilots.METHOD: European National Aviation Authorities (NAAs) were requested to provide data concerning the total number of pilots that were examined, their age and license category, number of unfit pilots, and the medical causes of each case of grounding. Diagnoses were classified according to the format and definitions laid down in Commission Regulation (EU) No. 1178/2011 Part Med.RESULTS: Analyzed were 82,435 cases assessed by 6 NAAs. Of these cases, 2.1% were assessed as unfit to fly. Frequent causes for grounding a pilot were cardiovascular (19%), psychiatric (11%), neurological (10%), and psychological (9%). Cardiovascular conditions were the most frequent cause for grounding in the older age groups, with 21% in the age 51-60 cohort, 28% in the age 61-65 cohort, and 48% in those beyond 65 yr. Psychiatric and psychological diagnoses were most frequent in the age 20-40 cohort.DISCUSSION: Cardiovascular conditions were the most frequent cause for grounding. Cardiovascular diseases (CVD) are associated with modifiable risk factors. Tackling these risk factors gives aeromedical examiners the opportunity to improve the health of pilots and reduce CVD-related flight safety risks by reducing the number of pilots at risk of in-flight incapacitation. The mandatory periodical medical examination of pilots provides an excellent framework for risk prevention and follow-up of preventive measures.Simons R, Maire R, Van Drongelen A, Valk P. Grounding of pilots: medical reasons and recommendations for prevention. Aerosp Med Hum Perform. 2021; 92(12):950-955.

Continuous Glucose Monitoring for In-Flight Measurement of Glucose Levels of Insulin-Treated Pilots.

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.

Cognitive Performance Effects of Bilastine 20 mg During 6 Hours at 8000 ft Cabin Altitude.

INTRODUCTION: Bilastine is a new oral, second generation antihistamine used in the symptomatic treatment of allergic rhinoconjunctivitis and urticaria. It is considered a nonsedating antihistamine and might be recommended for use in pilots, pending research on the effects on flying-related performance under hypobaric conditions that prevail in an airliner. We assessed the effects of a single dose of bilastine 20 mg on alertness and complex task performance of healthy volunteers in a hypobaric chamber at 75.2 kPa (8000 ft/2438 m cabin altitude). METHODS: In a randomized, double-blind, crossover study, 24 volunteers received a single dose of bilastine 20 mg, hydroxyzine 50 mg (active control), and placebo. Using the Vigilance and Tracking Task, Multi-Attribute Task Battery, and Stanford Sleepiness Scale, assessments were made before and up to 6 h after intake of the study medication. RESULTS: Bilastine 20 mg had no impairing effects on sleepiness levels, vigilance, or complex task performance for up to 6 h post-dose. Hydroxyzine 50 mg (active control) was associated with significant sleepiness and impaired performance across this time period, confirming the sensitivity of the tests. CONCLUSION: Bilastine 20 mg did not cause sleepiness or impaired performance on tasks related to flying. It is anticipated that a single dose of bilastine 20 mg will not affect flying performance. Bilastine may provide a safe therapeutic alternative for pilots suffering from allergic rhinitis or urticaria. Our findings might also have implications for the treatment of allergic disorders of personnel involved in other safety-sensitive jobs. Valk PJL, Simons R, Jetten AM, Valiente R, Labeaga L. Cognitive performance effects of bilastine 20 mg during 6 hours at 8000 ft cabin altitude. Aerosp Med Hum Perform. 2016; 87(7):622-627.

Use of Gene Expression Biomarkers to Predict Suicidality.

Since the tragic accident of Germanwings flight 4U9525, there has been discussion about methods to identify and prevent suicidality in pilots. Neurogenetic scientists claim that biomarker tests for suicidality as part of healthcare assessments may lead to early identification of suicidal behavior. In this commentary the value of these gene expression biomarkers for aeromedical purposes is evaluated based on relevant literature. It is concluded that the currently identified biomarkers for suicidality need thorough validation before they can be used. The aeromedical examiner's most important tool is still an anamnesis, in which warning signs of suicidal behavior can be picked up. Simons R. Use of gene expression biomarkers to predict suicidality. Aerosp Med Hum Perform. 2016; 87(7):659-660.

Health risk assessment of exposure to TriCresyl Phosphates (TCPs) in aircraft: a commentary.

Possible exposure to TriCresyl Phosphates (TCPs) has led to concerns among airline crew members. One isomer, Tri-ortho-Cresyl Phosphate (ToCP) is known to be neurotoxic and exposure to ToCP via contaminated cabin air has been suggested to be associated with the alleged Aerotoxic syndrome. The symptoms associated with Aerotoxic syndrome are diverse, including headaches, loss of balance, numbness and neurobehavioral abnormalities such as emotional instability, depression and cognitive dysfunction. Other ortho-isomers are toxic as well, but the non-ortho isomers are regarded as less toxic. In a collaborative effort to increase insight into the possible association between exposure to TCPs via contaminated cabin air and Aerotoxic syndrome, we performed an exposure- and toxicological risk assessment. Measurements in KLM 737 aircraft have demonstrated the presence of non-ortho isomers in low concentrations, though ToCP and other ortho-isomers could not be detected. Based on this exposure assessment, we established a toxicological risk model that also takes into account human differences in bioactivation and detoxification to derive a hazard quotient. From this model it appears unlikely that the health effects and alleged Aerotoxic syndrome are due to exposure to ToCP. Alternative explanations for the reported symptoms are discussed, but evaluation of the current findings in light of the criteria for occupational disease leads to the conclusion that the Aerotoxic Syndrome cannot be regarded as such. Additional research is thus required to unravel the underlying causes for the reported health complaints.

Effects of dexamphetamine with and without alcohol on simulated driving.

RATIONALE: In party circuits dexamphetamine is frequently used in combination with alcohol. It is hypothesized that co-administration of dexamphetamine to alcohol might reduce the sedative effects of alcohol, but may potentiate risk-taking behaviour. OBJECTIVES: The study was aimed at assessing the effects of alcohol, dexamphetamine and the combination of both on simulated driving and cognitive performance. METHOD: Eighteen subjects participated in a randomized, crossover, placebo-controlled study employing four conditions: 10 mg dexamphetamine, 0.8 g/kg alcohol, 10 mg dexamphetamine + 0.8 g/kg alcohol, and placebo. Fundamental driving skills and risk-taking behaviour were assessed in a driving simulator. Subjects also completed vigilance and divided attention tasks, and subjective ratings. RESULTS: Mean BAC levels during simulated driving were between 0.91‰ and 0.64‰. Subjects using alcohol showed a significantly larger mean standard deviation of lateral position and shorter accepted gap time and distance. Use of alcohol or dexamphetamine + alcohol was associated with a higher frequency of red light running and collisions than the dexamphetamine or placebo conditions. Performance of vigilance and divided attention tasks was significantly impaired in the alcohol condition and, to a lesser degree, in the dexamphetamine + alcohol condition. CONCLUSION: Single doses of 0.8 g/kg alcohol increased risk-taking behaviours and impaired tracking, attention and reaction time during a 3-h period after drinking when BACs declined from 0.9 to 0.2 mg/ml. The stimulatory effects of co-administration of dexamphetamine 10 mg were not sufficient to overcome the impairing effects of alcohol on skills related to driving.

[Doctor, may I travel in space? Aeromedical considerations regarding commercial suborbital space flights]. / Dokter, mag ik de ruimte in? Vliegmedische overwegingen bij de commerciële ruimtevaart.

Within a few years, the first commercial operators will start flying passengers on suborbital flights to the verge of space. Medical data on the effects of space journeys on humans have mainly been provided by professional astronauts. There is very little research into the aeromedical consequences of suborbital flights for the health of untrained passengers. Low air pressure and oxygen tension can be compensated for by pressurising the spacecraft or pressure suit. Rapid changes in gravitational (G-)force pose ultimate challenges to cardiovascular adaptation mechanisms. Zero-gravity and G-force may cause motion sickness. Vibrations and noise during the flight may disturb communication between passengers and crew. In addition, the psychological impact of a suborbital flight should not be underestimated. There are currently no legal requirements available for medical examinations for commercial suborbital flights, but it seems justifiable to establish conditions for potential passengers' states of health.

Sleep and alertness in North Sea helicopter operations.

INTRODUCTION: Dutch North Sea helicopter operations are characterized by multiple sector flights to offshore platforms under difficult environmental conditions. In the context of a Ministry of Transport program to improve safety levels of helicopter operations, we assessed effects of pre-duty sleep, pre-duty travel time, and workload factors on the alertness and vigilance of pilots. METHOD: Data of 24 pilots comprising 224 duty days were analyzed. Pilots performed 10-min test sessions after wake up, pre-duty, halfway-duty, end-duty, and at bedtime during normal duty rosters. Test sessions included completion of a vigilance task, vigor and sleepiness ratings, and questions on sleep and operational characteristics. Pilots wore an actometer to objectify sleep data. RESULTS: Vigor scores were high and sleepiness levels were low during the entire flight duty periods (FDPs), while vigilance was impaired only 6.8% in the course of the FDPs. Pre-duty sleep before morning duties was 1.5 h shorter than sleep before duties starting after midday. Longer pre-duty travel time was correlated with shorter pre-duty sleep and lower vigilance levels during duty. CONCLUSION: During the FDPs, pilots maintained alertness and vigilance levels that may be considered safe in terms of alertness-related flight safety. This favorable outcome may be attributed to reasonable length of FDPs, favorable circadian start and end times of duties, sufficient opportunities for restorative pre-duty sleep, and relatively good weather conditions. Appropriate FDP scheduling is an important measure to optimize alertness of helicopter pilots who have to cope with adverse environmental conditions and limited landing and air traffic control facilities.

Leisure pilot license proposed for Europe: do you want such pilots crossing your flight path?

In a Notice of Proposed Amendment, the European Aviation Safety Agency proposes to introduce a Leisure Pilot License (LPL). Holders of a LPL for airplanes will be allowed to fly single-engine piston airplanes with a maximum takeoff mass of 2000 kg or less, carrying a maximum of three passengers. In this commentary paper, we express significant concern about the flight safety consequences of the proposed aeromedical requirements of the LPL. We argue that the proposed minimum age, validity period of the medical certificate, and issuance of certificates by general practitioners may increase the flight safety risk. Major revision of the proposed LPL regulation is recommended.

Fluid loss does not explain coagulation activation during air travel.

The mechanism of air travel-related venous thrombosis is unclear. Although immobility plays a pivotal role, other factors such as fluid loss may contribute. We investigated whether fluid loss occurred more in individuals with coagulation activation after air travel than in subjects without. As a secondary aim, we investigated whether fluid loss per se occurred during air travel. In this crossover study, 71 healthy volunteers were exposed to eight hours of air travel, eight hours immobilization in a cinema, and a daily-life control situation. Markers of fluid loss (haematocrit, serum osmolality and albumin) and of coagulation activation were measured before and after each exposure. The study included 11 volunteers with and 55 volunteers without coagulation activation during the flight. The change in parameters of fluid loss was not different in volunteers with an activated clotting system from those without (difference between groups in haematocrit: -0.6%, 95% confidence interval [CI]: -1.9 to 0.6). On a group level, mean haematocrit values decreased during all three exposures. However, in some individuals it increased, which occurred in more participants during the flight (34%; 95% CI 22 to 46) than during the daily-life situation (19%; 95% CI 10 to 28). These findings do not support the hypothesis that fluid loss contributes to thrombus formation during air travel.

Usefulness of temazepam and zaleplon to induce afternoon sleep.

UNLABELLED: Insufficient daytime sleep may result in reduction of effectiveness and safety during overnight military missions. The usefulness of temazepam and zaleplon to optimize afternoon sleep and their effects on performance and alertness during a subsequent night shift were studied. METHOD: In a randomized double-blind within-subjects design, 11 subjects took 20 mg of temazepam, 10 mg of zaleplon, or placebo before a 5:30-10:00 p.m. sleep period. Sleep length and quality were measured. Subjects were kept awake throughout the night while alertness, cognitive performance, and muscle power were repeatedly measured. RESULTS: Temazepam provided significantly longer and qualitatively better sleep than zaleplon or placebo. During the night, sleepiness increased and muscle power was impaired in all conditions. Better sleep was correlated with less sleepiness during the night. CONCLUSION: Temazepam is useful to optimize a 4.5-hour afternoon sleep before overnight missions. Irrespective of hypnotic treatment, sleepiness and fatigue increased during the night shift.

Malaria prophylaxis for aircrew: safety of atovaquone/proguanil in healthy volunteers under aircraft cabin pressure conditions.

BACKGROUND: Because malaria in endemic areas presents a serious threat to the health of aircrew, optimal prevention is important. An effective and safe prophylactic antimalarial drug is needed. The combination of 250 mg atovaquone with 100 mg proguanil HCl (atovaquone/proguanil, or A/P) has shown good prophylactic efficacy and tolerance for prevention of falciparum malaria. However, medication for use by aircrew on duty is subject to approval by national and international aviation authorities, who require convincing evidence that the treatment has no negative effects on the flight performance of crews. The purpose of the present study was to evaluate the risk of detrimental effects of atovaquone/proguanil on flight-related performance and alertness in healthy subjects under conditions of aircraft cabin pressure. METHODS: A randomized, double-blind crossover study was conducted in which 24 subjects were enrolled to use A/P and placebo, each in a 14-day prophylactic dosing regimen with a 21-day washout phase. Vigilance, alertness, complex information processing, and sleepiness were assessed in a hypobaric chamber at 75.2 kPa, which equals the lower limit of commercial aircraft cabin pressure. Furthermore, duration and quality of sleep at home were recorded during the 14 days of drug administration. RESULTS: Twenty-two subjects completed the study. No significant differences were found between the effects of placebo and A/P on vigilance, alertness, complex information processing, sleep duration and quality, and the occurrence of adverse effects. CONCLUSIONS: In-flight performance and alertness of aircrew will not be affected by the prophylactic use of A/P during a period of 14 days.

Desloratadine shows no effect on performance during 6 h at 8,000 ft simulated cabin altitude.

INTRODUCTION: Sustained vigilance is required by pilots and crew during flight; therefore, the use of antihistamines with sedating properties is widely prohibited. The purpose of this study was to determine the effects of desloratadine, a long-acting, nonsedating antihistamine, on healthy volunteers placed under conditions of simulated cabin pressure. METHODS: In a double-blind crossover study, 21 subjects randomly received single doses of desloratadine 5 mg, diphenhydramine 50 mg (active control), and placebo on different days separated by washout periods of 7 d. On test days, predose levels of alertness and fatigue were determined, as were post-dose levels at 1, 2, 3, 5, and 6 h. Measurements included vigilance and tracking, a multi-attribute task battery, the Stanford Sleepiness Scale, and pulse oximetry. RESULTS: Desloratadine had no detrimental effects on sleepiness or performance of tasks associated with flying ability. Conversely, diphenhydramine (active control) caused significantly more sleepiness than did the placebo [F (2,40) = 6.52, p < 0.01], as well as impaired performance (tracking performance p < 0.05 at 3 h post dose), and an increased percentage of omissions (p < 0.05 at 2 h post dose). CONCLUSION: A single dose of desloratadine 5 mg did not cause sleepiness and did not impair the performance of tasks associated with flying ability.

The use of actimetry to assess changes to the rest-activity cycle.

The endogenous circadian oscillator (the body clock) is slow to adjust to altered rest-activity patterns. As a result, several negative consequences arise during night work and after time-zone transitions. The process of adjustment can be assessed by measurements of the sleep electroencephalogram (EEG), core temperature or melatonin secretion, for example, but these techniques are very difficult to apply in field studies, and make very great demands upon both experimenters and subjects. We have sought to establish if the activity record, measured conveniently and unobtrusively by a monitor attached to the wrist, can be treated in ways that enable estimates to be made of the disruption caused by changes to the rest-activity cycle, and the process of adjustment to them. In Part A, we describe the calculation and assessment of a series of "activity indices" that measure the overall activity pattern, activity when out of bed or in bed, or the activity in the hours adjacent to going to bed or getting up. The value of the indices was assessed by measuring changes to them in subjects undergoing night work or undergoing time-zone transitions. In both cases, there is a large body of literature describing the changes that would be expected. First, night workers (working 2 to 4 successive night shifts) were investigated during rest days and night shifts. The indices indicated that night work was associated with lower activity when the subjects were out of bed and higher activity when in bed. Some indices also measured when subjects took an afternoon nap before starting a series of night shifts and gave information about the process of adjustment to night work and recovery from it. Second, in studies from travelers crossing six or more time zones to the east or west, the indices indicated that there were changes to the rest-activity cycle immediately after the flights, both in its overall profile and when activity of the subjects in bed or out of bed was considered, and that adjustment took place on subsequent days. By focusing on those indices describing the activity records during the last hour in bed (LHIB) and the first hour out of bed (FHOB), some evidence was found for incomplete adjustment of the body clock, and for differences between westward and eastward flights. In Part B, the battery of indices are applied to the activity records of long-haul pilots, whose activity patterns showed a mixture of effects due to night work and time-zone transitions. Actimetry was performed during the flights themselves and during the layover days (which were either rest or work days). The indices indicated that all pilots had disrupted rest-activity cycles caused by night flights, and that there were added problems for those who had also undergone time-zone transitions. Rest days were valuable for normalizing the activity profile. For those pilots who flew to the west, adjustment was by delay, though not all aspects of the rest-activity cycle adjusted immediately; for those who flew to the east, some attempted to advance their rest-activity cycle while others maintained home-based activity profiles. The indices indicated that the activity profile was disrupted more in those pilots who attempted to advance their rest-activity cycle. We conclude that objective estimates of the disruption caused to the rest-activity cycle and the circadian system can be obtained by suitable analysis of the activity record.