Assessing aeromedical risk: a three-dimensional risk matrix approach

Navigating Coronary Artery Disease in Aviation Cardiology in Australia and New Zealand

BACKGROUND

Cardiologists will commonly assess patients who hold an aviation medical certificate and require unique assessments and communications with national civil aviation authorities (in Australia, the Civil Aviation Safety Authority [CASA] and in New Zealand, the Civil Aviation Authority of New Zealand [CAA NZ]). Cardiac conditions are the most common reason for disqualification from holding an aviation licence, and coronary artery disease is considered a high-risk condition for pilot incapacitation.

AIM

To provide a contemporary update on the aeromedical approach to the evaluation, detection, and management of coronary artery disease in an Australasian context.

METHODS

A narrative view of current and historical practice in the area of aeromedical evaluation of coronary disease was undertaken.

RESULTS

This review highlights the aeromedical approach to risk stratification and specific challenges of the aviation environment for patients with coronary artery disease. Scenarios of coronary artery disease screening, common and rare acute coronary syndromes, and the assessment of established coronary artery disease are examined in detail. Suggestions to facilitate communications between specialists and CASA or CAA NZ to facilitate patient re-certification are also provided.

CONCLUSION

Patients who are pilots have unique requirements in terms of their coronary assessment, management, and follow-up to maintain eligibility to fly. It is important for cardiologists to be aware of relevant occupational requirements to provide optimal care to their patients.

Aeromedical Risk of Migraine

INTRODUCTION: Migraine is a common condition that can carry considerable risk to aeromedical duties. Because randomized controlled trials are not an appropriate method to evaluate flight safety risk for medical conditions that may cause subtle or sudden incapacitation, the determination of fitness-to-fly must be based on risk assessments informed by extrapolated evidence. Therefore, we conducted a review of current literature to provide background information to inform the aeromedical risk assessment of migraine using a risk matrix approach.METHODS: We identified studies on topics pertinent to conducting an aeromedical risk assessment of migraine. We generated an overview of the literature synthesizing the findings of articles retrieved from searches of Scopus, Ovid, PubMed, and the Cochrane Library published in English from all years, in both general and aircrew populations. International headache and neurology guidelines, as well as headache policies from the U.S. Air Force, were also reviewed.RESULTS: This review includes information on the following topics relevant to conducting an evidence-based risk assessment of migraine: diagnosis, prevalence, incidence, natural course, clinical presentation, triggers, comorbidities, neuroimaging, implications of family history, and efficacy of pharmacological and nonpharmacological therapies.DISCUSSION: This review summarizes current literature on migraine for use in a risk matrix approach to the aeromedical assessment of migraine in prospective and current aircrew. Awareness of the most current epidemiological data related to a variety of migraine parameters facilitates an evidence-based risk assessment of migraine in aircrew and requires iterative updates as new information becomes available.Mainland RL, Skinner CR, Saary J. Aeromedical risk of migraine. Aerosp Med Hum Perform. 2024; 95(2):101-112.

The risk matrix: Drug-related deaths in prisons in England and Wales, 2015-2020

This article explores the factors contributing to drug-related deaths in English and Welsh prisons between 2015 and 2020. Based on content analysis of all Prison and Probation Ombudsman 'other non-natural' fatal incident investigation reports, descriptive statistics were generated. Qualitative analysis explored the circumstances surrounding deaths and key risk factors. Most deaths were of men, whose mean age was 39 years. Drug toxicity was the main factor in causing death, exacerbated by underlying physical health conditions and risk-taking behaviours. A variety of substances were involved. New psychoactive substances became more important over time. A high proportion had recorded histories of substance use and mental illness. During this period, the prison system was under considerable stress creating dangerous environments for drug-related harm. This study highlights the process of complex interaction between substances used, individual characteristics, situational features and the wider environment in explaining drug-related deaths in prisons. Implications for policy and practice are discussed.

Tourist risk assessment of pollen allergy in tourism attractions: A case study in the Summer Palace, Beijing, China

Pollen allergy has already been an increasingly prominent ecosystem disservice in tourism attractions. However, few studies have assessed the tourist risk of pollen allergy through integrating multidisciplinary knowledge of ecology, medicine, phenology, and risk management. Basing on the conceptual framework of risk assessment proposed by UNISDR, we first established an index system of pollen-allergy risk for tourists in attractions and outlined assessment methods 18 available indexes were put forward to cover three aspects: hazard of plant allergen, tourist vulnerability, and resilience of assessment units. Subsequently, taking the Summer Palace as the case study area, we conducted a tourist risk assessment of pollen allergy. Values of nine available indexes were obtained via ecological investigation, phenological observation, and data mining of visitors' logs on Sina Weibo. Risk levels of spring pollen allergy for tourists in different assessment units were revealed by combining the green zone allergenicity index model and three-dimensional risk assessment matrix. The results showed that: (1) There were seven primary pollen-allergenic plants in the Summer Palace, including Platycladus orientalis, Sabina chinensis, Salix babylonica, Pinus tabulaeformis, Populus tomentosa Carr, Morus alba L. and Fraxinus chinesis, among which Platycladus orientalis and Salix babylonica were the highest allergenic. (2) Among 18 spots, tourists faced the highest risk level of pollen allergy in spring at three spots, namely the Hall of Serenity, Hall of Benevolence and Longevity, and Gallery of Literary and Prosperity. (3) The two routes of the Long Corridor and Longevity Hill scored high on the risk level. (4) Among four areas, risk levels of the Front-hill and Rear-hill areas were high. Given the increasing spatial-temporal uncertainty of pollen allergy and tourist behaviors under global warming and urbanization, the related monitoring should be strengthened in the future. Furthermore, the dynamic and improved assessment of pollen-allergy risk should be institutionalized and be integrated into the evaluation of tourism experience quality. Tourism administration should make full use of relevant assessment results and conduct more effective risk communication.

Endogenous Risk Factors of Cardiovascular Diseases (CVDs) in Military Professionals with a Special Emphasis on Military Pilots

Cardiovascular disease (CVD) risk factors can be categorized as non-modifiable and modifiable. Modifiable risk factors include some exogenous and behavioral factors that can be easily modified, whereas endogenous modifiable risk factors, such as hypertension, hyperlipidemia, diabetes, or obesity may be modified to a limited extend. An increased prevalence of CVDs as well as their risk factors have been observed in military personnel, as specific military-related stressors are highly correlated with acute cardiac disorders. Military pilots are a subpopulation with great CVD risk due to an accumulation of different psychological and physical stressors also considered to be CVD risk factors. This review presents data concerning CVD risk in military professionals, with a special emphasis on military pilots and crew members. We also discuss the usefulness of novel indicators related to oxidative stress, inflammation, or hormonal status as well as genetic factors as markers of CVD risk. For a correct and early estimation of CVD risk in asymptomatic soldiers, especially if no environmental risk factors coexist, the scope of performed tests should be increased with novel biomarkers. An indication of risk group among military professional, especially military pilots, enables the implementation the early preventive activities, which will prolong their state of health and military suitability.

Cardiovascular risk in high-hazard occupations: the role of occupational cardiology

Work is beneficial for health, but many individuals develop cardiovascular disease (CVD) during their working lives. Occupational cardiology is an emerging field that combines traditional cardiology sub-specialisms with prevention and risk management unique to specific employment characteristics and conditions. In some occupational settings incapacitation through CVD has the potential to be catastrophic due to the nature of work and/or the working environment. These are often termed 'hazardous' or 'high-hazard' occupations. Consequently, many organizations that employ individuals in high-hazard roles undertake pre-employment medicals and periodic medical examinations to screen for CVD. The identification of CVD that exceeds predefined employer (or regulatory body) risk thresholds can result in occupational restriction, or disqualification, which may be temporary or permanent. This article will review the evidence related to occupational cardiology for several high-hazard occupations related to aviation and space, diving, high altitude, emergency workers, commercial transportation, and the military. The article will focus on environmental risk, screening, surveillance, and risk management for the prevention of events precipitated by CVD. Occupational cardiology is a challenging field that requires a broad understanding of general cardiology, environmental, and occupational medicine principles. There is a current lack of consensus and contemporary evidence which requires further research. Provision of evidence-based, but individualized, risk stratification and treatment plans is required from specialists that understand the complex interaction between work and the cardiovascular system. There is a current lack of consensus and contemporary evidence in occupational cardiology and further research is required.

Methodology for Evaluating Risk of Visual Inspection Tasks of Aircraft Engine Blades

Risk assessment methods are widely used in aviation, but have not been demonstrated for visual inspection of aircraft engine components. The complexity in this field arises from the variety of defect types and the different manifestation thereof with each level of disassembly. A new risk framework was designed to include contextual factors. Those factors were identified using Bowtie analysis to be criticality, severity, and detectability. This framework yields a risk metric that describes the extent to which a defect might stay undetected during the inspection task, and result in adverse safety outcomes. A simplification of the framework provides a method for go/no-go decision-making. The results of the study reveal that the defect detectability is highly dependent on specific views of the blade, and the risk can be quantified. Defects that involve material separation or removal such as scratches, tip rub, nicks, tears, cracks, and breaking, are best shown in airfoil views. Defects that involve material deformation and change of shape, such as tip curl, dents on the leading edges, bents, and battered blades, have lower risk if edge views can be provided. This research proposes that many risk assessments may be reduced to three factors: consequence, likelihood, and a cofactor. The latter represents the industrial context, and can comprise multiple sub-factors that are application-specific. A method has been devised, including appropriate scales, for the inclusion of these into the risk assessment.

Cabin crew health and fitness-to-fly: Opportunities for re-evaluation amid COVID-19

Aircrew fitness-to-fly is among the elements that make aviation the safest form of long-distance transport. The health of cabin crew is a crucial determinant in carrying out safety-related duties. 'Fitness-to-fly' is associated with defined workplace conditions, for which airlines have a legal duty to ensure fitness for employment. We explored the literature on fitness-to-fly to obtain a pragmatic assessment of the challenges for aeromedical examinations. Regulations promulgated by aviation regulatory authorities and airline-internal policies have similar status and meaning, yet there is no harmonised approach internationally, and an inability to conform periodic medical assessments to actual operational fitness. The COVID-19 pandemic has highlighted the need to better understand fitness-to-fly criteria. Fitness-to-fly measures are mainly based on self-reported data and there is a need for a 'safety' factor for self-reports. Aeromedical evaluations should evolve from meeting medical standards to include pandemics as an element of the overall risk of aircraft operations. Re-evaluating criteria for fitness-to-fly assessment will further the goal of linking research to the actual needs of public health decisionmakers. If airlines are to resume operations at pre-pandemic levels, they must demonstrate to the public and public health agencies that fitness-to-fly assessment is appropriate and effective.

Return to flying after coronary artery disease: A case series among Malaysian pilots

OBJECTIVES

Pilots with coronary artery disease (CAD) are at increased risk of myocardial infarction, stroke, and possibly death. Return to flying duties may be considered after a detailed risk assessment. The aim of this retrospective case series is to describe the return to flying duty process.

METHODS

We conducted a retrospective case review of pilots diagnosed with CAD at the Institute of Aviation Medicine (IAM), Royal Malaysian Air Force (RMAF) in October 2020.

RESULTS

Thirteen cases of CAD were included in the review. Ten pilots were diagnosed after developing acute coronary syndrome; the remaining three pilots were diagnosed during a routine medical examination via an exercise stress test. Twelve pilots required a revascularization procedure. A total of 11 pilots (84.6%) were recertified for flying duties, while another two were disqualified. The duration to recertification for these 11 pilots was between three months and one year.

CONCLUSIONS

The risk assessment was initiated with initial risk-stratification using population-appropriate risk calculator combined with the 4 × 4 aeromedical risk matrix. The reassessment of return to flying after coronary artery disease must be carried out no sooner than six months after the event. Pilots must be hemodynamically stable with no evidence of significant inducible ischemic left and a minimum 50% of ventricular ejection fraction (LVEF). A follow-up is recommended at the initial six months after recertification and then annually with a routine noninvasive cardiac assessment.

Coronary Artery Disease Screening Using CT Coronary Angiography

BACKGROUND: The increased utility of CT coronary angiography (CTCA) in cardiovascular screenings of aircrew has led to the increased detection of asymptomatic coronary artery disease (CAD). A systematic review of studies relevant to the interpretation of CTCA for the occupational fitness assessment of high-risk vocations was performed, with findings used to describe the development of a pathway for the aeromedical disposition of military aviators with asymptomatic CAD.METHODS: Medline was searched using the terms CT coronary angiogram and screening and prognosis. The inclusion criteria were restricted to study populations ages > 18 yr, were asymptomatic, were not known to have CAD, had undergone CTCA, and with their associations with major adverse cardiovascular events (MACE) and other relevant cardiac outcomes reported.RESULTS: Included in this systematic review were 10 studies. When compared to subjects with no or nonobstructive CAD, those with obstructive CAD on CTCA had hazard ratios (HR) for cardiac events ranging from 1.42 to 105.48. Comparing subjects with nonobstructive CAD and those without CAD on CTCA, a lower HR of 1.19 for cardiac events was found. The annual event rates of subjects with no CAD on CTCA were extremely low, ranging from 0 to 0.5%.CONCLUSIONS: Based on the findings, we suggest that CTCA should only be performed in aircrew with higher cardiac risk profiles. Those found to have no CAD or minimal CAD (i.e., 25% stenosis) in a non-left main coronary artery on CTCA can be returned to flying duties. All other results should be further evaluated with an invasive angiogram.Cheong RWL, See B, Tan BBC, Koh CH. Coronary artery disease screening using CT coronary angiography. Aerosp Med Hum Perform. 2020; 91(10):812817.

Management of established coronary artery disease in aircrew without myocardial infarction or revascularisation

This paper is part of a series of expert consensus documents covering all aspects of aviation cardiology. In this manuscript, we focus on the broad aviation medicine considerations that are required to optimally manage aircrew with established coronary artery disease in those without myocardial infarction or revascularisation (both pilots and non-pilot aviation professionals). We present expert consensus opinion and associated recommendations. It is recommended that in aircrew with non-obstructive coronary artery disease or obstructive coronary artery disease not deemed haemodynamically significant, nor meeting the criteria for excessive burden (based on plaque morphology and aggregate stenosis), a return to flying duties may be possible, although with restrictions. It is recommended that aircrew with haemodynamically significant coronary artery disease (defined by a decrease in fractional flow reserve) or a total burden of disease that exceeds an aggregated stenosis of 120% are grounded. With aggressive cardiac risk factor modification and, at a minimum, annual follow-up with routine non-invasive cardiac evaluation, the majority of aircrew with coronary artery disease can safely return to flight duties.

Impact of stressors in the aviation environment on xenobiotic dosimetry in humans: physiologically based prediction of the effect of barometric pressure or altitude

Standard health risks from volatile organic compounds (VOCs) are generally interpreted at ambient environmental conditions. The aim of this study was to develop a strategy for using physiologically based pharmacokinetic (PBPK) modeling to compare known risks in the general population to calculated risks in pilots experiencing pressure-based stressors. PBPK models facilitate these comparisons by prediction of how target-tissue specific doses are altered when a stressor, such as high altitude, produces changes in physiological parameters. Cardiac output, regional blood flow, and alveolar ventilation rate following acute exposure to altitude ranging from moderate to extremely high were estimated from published data from 52 groups of human subjects. Scenarios where pilots might inhale toluene, 1,2,4-trimethylbenzene (1,2,4-TMB), or cyclohexane during routine military flight training were simulated. At the recommended Threshold Limit Values (TLV), arterial blood concentrations were predicted to be higher for exposure at 15000 ft (4572 m) than at sea level. The differences were greater for toluene and TMB, which have higher blood: air and fat: blood partition coefficients than less lipophilic cyclohexane. In summary, quantitative approaches to internal dosimetry prediction that take advantage of existing knowledge of physiological changes induced by occupational stressors possess potential as tools in performing a human health risk assessment.

Novel Approach for Detecting the Neurological or Behavioral Impact of Physiological Episodes (PEs) in Military Aircraft Crews

Introduction

Military and civil aviation have documented physiological episodes among aircrews. Therefore, continued efforts are being made to improve the internal environment. Studies have shown that exposures to many organic compounds present in emissions are known to cause a variety of physiological symptoms. We hypothesize that these compounds may reversibly inhibit acetylcholinesterase, which may disrupt synaptic signaling. As a result, neural proteins leak through the damaged blood-brain barrier into the blood and in some, elicit an autoimmune response.

Materials and Methods

Neural-specific autoantibodies of immunoglobulin-G (IgG) class were estimated by the Western blotting technique in the sera of 26 aircrew members and compared with the sera of 19 normal healthy nonaircrew members, used as controls.

Results

We found significantly elevated levels of circulating IgG-class autoantibodies to neurofilament triplet proteins, tubulin, microtubule-associated tau proteins (Tau), microtubule-associated protein-2, myelin basic protein, and glial fibrillary acidic protein, but not S100 calcium-binding protein B compared to healthy controls.

Conclusion

Repetitive physiological episodes may initiate cellular injury, leading to neuronal degeneration in selected individuals. Diagnosis and intervention should occur at early postinjury periods. Use of blood-based biomarkers to assess subclinical brain injury would help in both diagnosis and treatment.

An introduction to aviation cardiology

The management of cardiovascular disease (CVD) has evolved significantly in the last 20 years; however, the last major publication to address a consensus on the management of CVD in aircrew was published in 1999, following the second European Society of Cardiology conference of aviation cardiology experts. This article outlines an introduction to aviation cardiology and focuses on the broad aviation medicine considerations that are required to manage aircrew appropriately and optimally (both pilots and non-pilot aviation professionals). This and the other articles in this series are born out of a 3 year collaborative working group between international military aviation cardiologists and aviation medicine specialists, many of whom also work with and advise civil aviation authorities, as part of a North Atlantic Treaty Organization (NATO) led initiative to address the occupational ramifications of CVD in aircrew (HFM-251). This article describes the types of aircrew employed in the civil and military aviation profession in the 21st century; the types of aircraft and aviation environment that must be understood when managing aircrew with CVD; the regulatory bodies involved in aircrew licensing and the risk assessment processes that are used in aviation medicine to determine the suitability of aircrew to fly with medical (and specifically cardiovascular) disease; and the ethical, occupational and clinical tensions that exist when managing patients with CVD who are also professional aircrew.

Non-coronary cardiac surgery and percutaneous cardiology procedures in aircrew

This manuscript focuses on the broad aviation medicine considerations that are required to optimally manage aircrew following non-coronary surgery or percutaneous cardiology interventions (both pilots and non-pilot aviation professionals). Aircrew may have pathology identified earlier than non-aircrew due to occupational cardiovascular screening and while aircrew should be treated using international guidelines, if several interventional approaches exist, surgeons/interventional cardiologists should consider which alternative is most appropriate for the aircrew role being undertaken; liaison with the aircrew medical examiner is strongly recommended prior to intervention to fully understand this. This is especially important in aircrew of high-performance aircraft or in aircrew who undertake aerobatics. Many postoperative aircrew can return to restricted flying duties, although aircrew should normally not return to flying for a minimum period of 6 months to allow for appropriate postoperative recuperation and assessment of cardiac function and electrophysiology.

Congenital heart disease in aircrew

This article focuses i on the broad aviation medicine considerations that are required to optimally manage aircrew ii with suspected or confirmed congenital heart disease (both pilots and non-pilot aviation professionals). It presents expert consensus opinion and associated recommendations and is part of a series of expert consensus documents covering all aspects of aviation cardiology. This expert opinion was born out of a 3 year collaborative working group between international military aviation cardiologists and aviation medicine specialists, as part of a North Atlantic Treaty Organization (NATO) led initiative to address the occupational ramifications of cardiovascular disease in aircrew (HFM-251) many of whom also work with and advise civil aviation authorities.