Early Online.

BACKGROUND: Long-haul flights have been associated with a two- to four-fold increased risk of aviation-related thrombosis (ART). Several studies have investigated the extent to which hypoxic hypobaric exposure, dehydration and prolonged immobilisation during air travel induce changes in haemostasis. OBJECTIVE: To investigate the role of high altitude as a risk factor for ART. METHODS: Healthy volunteers aged ≥18 years (N=40), without risk factors for venous thromboembolism, were exposed to an exacerbated altitude of 18 000 feet (5 486 m) for 1 hour. During the flight, the oxygen (O2) levels of the participants, who received supplemental O2, were measured by pulse oximetry and maintained at >92%. Venous blood and urine samples were collected prior to departure and immediately after flying in an unpressurised twin-engine airplane. D-dimer levels, thromboelastography (TEG) parameters, von Willebrand factor (VWF) activity and urine osmolality were measured. RESULTS: The participants were 19 men and 21 women, with a mean (standard deviation) age of 46 (14) years. A significant difference in D-dimer levels, VWF activity, urine osmolality and TEG parameters (reaction (R) time, kinetic (K) time and maximum amplitude (MA)) before and after the 1-hour flight was observed (p<0.001). Urine osmolality correlated positively with VWF activity levels (r=0.469; p<0.002). CONCLUSION: Air travel at high altitude induced a hypercoagulable state in healthy volunteers. Future research should focus on whether thromboprophylaxis can significantly obviate the activation of coagulation in response to high altitude.

Global Mpox spread due to increased air travel.

Mpox is an emerging, infectious disease that has caused outbreaks in at least 91 countries from May to August 2022. We assessed the link between international air travel patterns and Mpox transmission risk, and the relationship between the translocation of Mpox and human mobility dynamics after travel restrictions due to the COVID-19 pandemic had been lifted. Our three novel observations were that: i) more people traveled internationally after the removal of travel restrictions in the summer of 2022 compared to pre-pandemic levels; ii) countries with a high concentration of global air travel have the most recorded Mpox cases; and iii) Mpox transmission includes a number of previously nonendemic regions. These results suggest that international airports should be a primary location for monitoring the risk of emerging communicable diseases. Findings highlight the need for global collaboration concerning proactive measures emphasizing realtime surveillance.

A methodology for estimating SARS-CoV-2 importation risk by air travel into Canada between July and November 2021.

BACKGROUND: Estimating rates of disease importation by travellers is a key activity to assess both the risk to a country from an infectious disease emerging elsewhere in the world and the effectiveness of border measures. We describe a model used to estimate the number of travellers infected with SARS-CoV-2 into Canadian airports in 2021, and assess the impact of pre-departure testing requirements on importation risk. METHODS: A mathematical model estimated the number of essential and non-essential air travellers infected with SARS-CoV-2, with the latter requiring a negative pre-departure test result. The number of travellers arriving infected (i.e. imported cases) depended on air travel volumes, SARS-CoV-2 exposure risk in the departure country, prior infection or vaccine acquired immunity, and, for non-essential travellers, screening from pre-departure molecular testing. Importation risk was estimated weekly from July to November 2021 as the number of imported cases and percent positivity (PP; i.e. imported cases normalised by travel volume). The impact of pre-departure testing was assessed by comparing three scenarios: baseline (pre-departure testing of all non-essential travellers; most probable importation risk given the pre-departure testing requirements), counterfactual scenario 1 (no pre-departure testing of fully vaccinated non-essential travellers), and counterfactual scenario 2 (no pre-departure testing of non-essential travellers). RESULTS: In the baseline scenario, weekly imported cases and PP varied over time, ranging from 145 to 539 cases and 0.15 to 0.28%, respectively. Most cases arrived from the USA, Mexico, the United Kingdom, and France. While modelling suggested that essential travellers had a higher weekly PP (0.37 - 0.65%) than non-essential travellers (0.12 - 0.24%), they contributed fewer weekly cases (62 - 154) than non-essential travellers (84 - 398 per week) given their lower travel volume. Pre-departure testing was estimated to reduce imported cases by one third (counterfactual scenario 1) to one half (counterfactual scenario 2). CONCLUSIONS: The model results highlighted the weekly variation in importation by traveller group (e.g., reason for travel and country of departure) and enabled a framework for measuring the impact of pre-departure testing requirements. Quantifying the contributors of importation risk through mathematical simulation can support the design of appropriate public health policy on border measures.

Investigating the challenges of air travel in the United States: a qualitative study of the lived experiences of wheelchair users with spinal cord injury or disorder.

STUDY DESIGN: Qualitative exploratory study. OBJECTIVES: To understand the lived experiences of individuals with spinal cord injuries or disorders (SCI/D) who use wheelchairs during air travel in the United States (US), with a focus on the challenges and barriers to accessing this form of transportation. SETTING: Wheelchair users with SCI/D living in the community in the US. METHODS: Semi-structured interviews were used to collect data from six wheelchair users with SCI/D. Data were analyzed using a six-step thematic analysis. RESULTS: Experiences of wheelchair users during air travel clustered into three themes; experiences interacting with the airport, experiences interacting with the airplane, and experiences across all stages of air travel. Barriers to airport accessibility were minimal. Physical barriers to airplane accessibility and damage to wheelchairs occurred when interacting with the airplane and airline staff. Undertrained staff and a shift in responsibility to the passenger with a disability impacted all stages of the experience. CONCLUSION: Wheelchair users with SCI/D encounter challenges that can result in unsafe and inaccessible air travel within the US. Adverse consequences of air travel often impact the individual's independence and quality of life during and after the flight. Participants provided recommendations to improve the air travel experience for wheelchair users, including the ability to remain in one's wheelchair while onboard the airplane.

Perception, confidence, and willingness to respond to in-flight medical emergencies among medical students: a cross sectional study.

BACKGROUND: In-flight medical emergencies (IMEs) are expected to increase as air travel normalized in the post-COVID-19 era. However, few studies have examined health professions students' preparedness to respond to such emergencies. Therefore, this study aimed to investigate medical students' knowledge, confidence, and willingness to assist during an IME in their internship program. METHODS: This cross-sectional survey utilized an online, self-administered questionnaire-based survey targeted at medical students at two medical colleges in Saudi Arabia. The questionnaire comprised three parts: sociodemographic characteristics, knowledge about aviation medicine (10 items), and confidence (7 items)/willingness (4 items) to assist during an IME. Odds Ratios (OR) and 95% Confidence Intervals (95%CI) were computed to detect potential associations between the knowledge levels and the other independent variables. Responses to confidence and willingness questions were scored on a 5-point Likert scale. RESULTS: Overall, 61.4% of participants had inadequate knowledge scores for providing care during an IME, and the proportion of participants did not differ between those who had or had not attended life support courses (60.4% vs. 66.7%, p > 0.99). Only frequency of air travel ≥ two times per year was associated with higher odds of adequate knowledge score [OR = 1.89 (95%CI 1.14-3.17), p = 0.02]. In addition, 93.3% of the participants had low, 6.3% had moderate, and 0.8% had high willingness scores, while 86.3% had low, 12.2% had moderate, and 1.5% had high confidence scores. There were no differences in the proportion of participants with low, moderate, and high willingness or confidence scores by attendance in life support courses. CONCLUSION: Even though over 8 in 10 students in our study had previously attended life support courses, the overwhelming majority lacked the knowledge, confidence, and willingness to assist. Our study underscores the importance of teaching medical students about IMEs and their unique challenges before entering their 7th-year mandatory general internship.

Temporal variations in international air travel: implications for modelling the spread of infectious diseases.

BACKGROUND: The international flight network creates multiple routes by which pathogens can quickly spread across the globe. In the early stages of infectious disease outbreaks, analyses using flight passenger data to identify countries at risk of importing the pathogen are common and can help inform disease control efforts. A challenge faced in this modelling is that the latest aviation statistics (referred to as contemporary data) are typically not immediately available. Therefore, flight patterns from a previous year are often used (referred to as historical data). We explored the suitability of historical data for predicting the spatial spread of emerging epidemics. METHODS: We analysed monthly flight passenger data from the International Air Transport Association to assess how baseline air travel patterns were affected by outbreaks of Middle East respiratory syndrome (MERS), Zika and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) over the past decade. We then used a stochastic discrete time susceptible-exposed-infected-recovered (SEIR) metapopulation model to simulate the global spread of different pathogens, comparing how epidemic dynamics differed in simulations based on historical and contemporary data. RESULTS: We observed local, short-term disruptions to air travel from South Korea and Brazil for the MERS and Zika outbreaks we studied, whereas global and longer-term flight disruptions occurred during the SARS-CoV-2 pandemic. For outbreak events that were accompanied by local, small and short-term changes in air travel, epidemic models using historical flight data gave similar projections of the timing and locations of disease spread as when using contemporary flight data. However, historical data were less reliable to model the spread of an atypical outbreak such as SARS-CoV-2, in which there were durable and extensive levels of global travel disruption. CONCLUSION: The use of historical flight data as a proxy in epidemic models is an acceptable practice, except in rare, large epidemics that lead to substantial disruptions to international travel.

Splenic Subcapsular Hematoma from Commercial Air Travel: Case Report of a Unique Incident of Altitude-Associated Splenic Syndrome.

BACKGROUND: Sickle cell trait (SCT), the heterozygous form of sickle cell disease, is generally thought of as a benign condition. However, it is possible for those with SCT to have serious complications, especially when they are exposed to high altitudes where oxygen levels are low. CASE REPORT: We present a case of a 41-year-old man with a history of SCT who developed severe epigastric pain and nearly lost consciousness while traveling on a commercial airplane. His twin brother, who also has SCT, had a similar episode in the past and required a splenectomy. A splenic subcapsular hematoma was found in a computed tomography scan of the abdomen and pelvis with intravenous contrast. He was admitted and managed conservatively until his symptoms resolved. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Though SCT is prevalent in our population, the complications that can arise, such as altitude-associated splenic syndrome, have likely not been thoroughly investigated. Physicians should add this condition to their differential if they practice at locations near airports or in areas of higher altitude and if their patients have a past medical history of SCT.

Understanding the impact of network structure on air travel pattern at different scales.

This study examines the global air travel demand pattern using complex network analysis. Using the data for the top 50 airports based on passenger volume rankings, we investigate the relationship between network measures of nodes (airports) in the global flight network and their passenger volume. The analysis explores the network measures at various spatial scales, from individual airports to metropolitan areas and countries. Different attributes, such as flight route length and the number of airlines, are considered in the analysis. Certain attributes are found to be more relevant than others, and specific network measure models are found to better capture the dynamics of global air travel demand than others. Among the models, PageRank is found to be the most correlated with total passenger volume. Moreover, distance-based measures perform worse than the ones emphasising the number of airlines, particularly those counting the number of airlines operating a route, including codeshare. Using the PageRank score weighted by the number of airlines, we find that airports in Asian cities tend to have more traffic than expected, while European and North American airports have the potential to attract more passenger volume given their connectivity pattern. Additionally, we combine the network measures with socio-economic variables such as population and GDP to show that the network measures could greatly augment the traditional approaches to modelling and predicting air travel demand. We'll also briefly discuss the implications of the findings in this study for airport planning and airline industry strategy.

COVID-19 passenger screening to reduce travel risk and translocation of disease.

Aviation passenger screening has been used worldwide to mitigate the translocation risk of SARS-CoV-2. We present a model that evaluates factors in screening strategies used in air travel and assess their relative sensitivity and importance in identifying infectious passengers. We use adapted Monte Carlo simulations to produce hypothetical disease timelines for the Omicron variant of SARS-CoV-2 for travelling passengers. Screening strategy factors assessed include having one or two RT-PCR and/or antigen tests prior to departure and/or post-arrival, and quarantine length and compliance upon arrival. One or more post-arrival tests and high quarantine compliance were the most important factors in reducing pathogen translocation. Screening that combines quarantine and post-arrival testing can shorten the length of quarantine for travelers, and variability and mean testing sensitivity in post-arrival RT-PCR and antigen tests decrease and increase with the greater time between the first and second post-arrival test, respectively. This study provides insight into the role various screening strategy factors have in preventing the translocation of infectious diseases and a flexible framework adaptable to other existing or emerging diseases. Such findings may help in public health policy and decision-making in present and future evidence-based practices for passenger screening and pandemic preparedness.

Pneumothorax and Timing to Safe Air Travel.

INTRODUCTION: Current guidelines regarding the time to flight after an acquired pneumothorax have been generally accepted and in place for years. The majority of these typically advise holding off on air travel until the complete resolution of a pneumothorax. Over the past decade, however, there has been an increase in the amount of literature focusing on this subject and challenging this well-held dogma. A review of these studies has shown that recent evidence contradicts the historical guidelines that many practitioners follow about the safety and timing of flying after pneumothoraces. Based on these studies, air travel with a known pneumothorax is likely safe and can be undertaken much sooner than current guidelines advise.Kashtan HW, Schulte SN, Connelly KS. Pneumothorax and timing to safe air travel. Aerosp Med Hum Perform. 2024; 95(2):113-117.

Quantitatively assessing early detection strategies for mitigating COVID-19 and future pandemics.

Researchers and policymakers have proposed systems to detect novel pathogens earlier than existing surveillance systems by monitoring samples from hospital patients, wastewater, and air travel, in order to mitigate future pandemics. How much benefit would such systems offer? We developed, empirically validated, and mathematically characterized a quantitative model that simulates disease spread and detection time for any given disease and detection system. We find that hospital monitoring could have detected COVID-19 in Wuhan 0.4 weeks earlier than it was actually discovered, at 2,300 cases (standard error: 76 cases) compared to 3,400 (standard error: 161 cases). Wastewater monitoring would not have accelerated COVID-19 detection in Wuhan, but provides benefit in smaller catchments and for asymptomatic or long-incubation diseases like polio or HIV/AIDS. Air travel monitoring does not accelerate outbreak detection in most scenarios we evaluated. In sum, early detection systems can substantially mitigate some future pandemics, but would not have changed the course of COVID-19.

Barotrauma inducido por vuelo en otorrinolaringología: Una revisión de la literatura / Flight-induced barotrauma in otorhinolaryngology: A literature review

Barotrauma se define como el daño tisular generado por diferencias de presión entre un espacio no ventilado dentro del cuerpo y el gas o fluido circundante. La causa más frecuente de barotrauma es el viaje en avión y se espera un aumento progresivo de los casos en el tiempo. Los órganos habitualmente comprometidos son el oído, cavidades paranasales y nervio facial. La fisiopatología del barotrauma por vuelo se fundamenta en la exposición a cambios bruscos de altitud y presión asociados a infecciones respiratorias altas y/o disfunción de la tuba auditiva. Los síntomas más frecuentes son otalgia, hipoacusia, tinnitus, vértigo y parálisis facial periférica. Muchas formas de barotrauma son autolimitadas y prevenibles mediante técnicas simples como la deglución de líquidos o maniobras de Valsalva durante las fases de ascenso o descenso. El tratamiento del barotrauma puede ser conservador, médico o quirúrgico, la decisión será individualizada de acuerdo con las características del paciente, gravedad del cuadro y recurrencias. Esto incluye el uso de descongestionantes orales y tópicos, dispositivos de autoinflación, técnicas quirúrgicas, entre otros. La mayoría de estas intervenciones se basan en recomendaciones de expertos y algoritmos extrapolados de guías clínicas para el manejo de otras patologías similares. Esta revisión presenta los principales hallazgos fisiopatológicos y clínicos, las opciones de tratamiento y las medidas preventivas para el barotrauma otorrinolaringológico inducido por el vuelo, en base a la evidencia disponible.

Barotrauma is defined as tissue damage caused by pressure differences between an unventilated space within the body and the surrounding gas or fluid. The most frequent cause of barotrauma is air travel, and a progressive increase in cases over time is expected. The most frequently affected organs are the ear, paranasal sinuses, and facial nerve. The pathophysiology of flight-induced barotrauma is based on exposure to sudden changes in altitude and pressure associated with upper respiratory tract infections and/or Eustachian tube dysfunction. The most frequent symptoms are otalgia, hypoacusis, tinnitus, dizziness, and peripheral facial palsy. Many forms of barotrauma are self-limiting and preventable through simple techniques such as swallowing fluids or performing Valsalva maneuvers during ascent or descent phases. The treatment of barotrauma can be either conservative, medical or surgical, according to patient's characteristics, severity of the condition, and recurrence. This includes the use of oral and topical decongestants, auto-inflation devices, surgical techniques, among others. Most of these interventions are based on expert recommendations and algorithms extrapolated from clinical guidelines for the management of other similar pathologies. This review presents key pathophysiologic and clinical findings, treatment options, and preventive measures for flight-induced otorhinolaryngologic barotrauma, based on available evidence.

Assessing the global risk of typhoid outbreaks caused by extensively drug resistant Salmonella Typhi.

Since its emergence in 2016, extensively drug resistant (XDR) Salmonella enterica serovar Typhi (S. Typhi) has become the dominant cause of typhoid fever in Pakistan. The establishment of sustained XDR S. Typhi transmission in other countries represents a major public health threat. We show that the annual volume of air travel from Pakistan strongly discriminates between countries that have and have not imported XDR S. Typhi in the past, and identify a significant association between air travel volume and the rate of between-country movement of the H58 haplotype of S. Typhi from fitted phylogeographic models. Applying these insights, we analyze flight itinerary data cross-referenced with model-based estimates of typhoid fever incidence to identify the countries at highest risk of importation and sustained onward transmission of XDR S. Typhi. Future outbreaks of XDR typhoid are most likely to occur in countries that can support efficient local S. Typhi transmission and have strong travel links to regions with ongoing XDR typhoid outbreaks (currently Pakistan). Public health activities to track and mitigate the spread of XDR S. Typhi should be prioritized in these countries.

CRM: Desarrollo de Aspectos Críticos Pendientes / CRM: Development of Pending Critical Aspects

La evolución de los programas de CRM ha supuesto para la aviación un enorme progreso en cuanto al estudio de los factores humanos y su relación con la reducción de los accidentes aéreos. Si bien es cierto que los programas de CRM han sufrido una exitosa evolución desde su aparición en 1979, no lo es menos, que los avances en la ciencia psicológica de las últimas décadas hacen necesario revisar y profundizar en aspectos ya abordados en etapas anteriores por dichos programas. Uno de estos aspectos es la importancia que presentan los Tripulantes de Cabina de Pasajeros (TCP) como integrantes del equipo de vuelo. Retrotrayéndose a los programas de CRM de tercera generación, el presente artículo analiza las actuaciones que han tenido los TCP en diferentes accidentes aéreos, poniendo de manifiesto la importancia que tiene su ejecución y la coordinación de la misma con la del resto de la tripulación de cara al éxito en la resolución de la emergencia aérea.(AU)

The evolution of CRM programs has meant enormous progress for aviation in terms of the study of human factors and their relationship with the reduction of air accidents. Although it is true that CRM programs have undergone a successful evolution since their appearance in 1979, it is no less true that the advances in psychological science in recent decades make it necessary to review and expand on aspects already addressed in previous stages by these programs. One of these aspects is the importance of the cabin crew members (CCM) as members of the flight team. Going back to the third generation programs, this paper analyzes the actions that the CCM have taken in different air accidents, highlighting the importance of their performance and their coordination with the rest of the crew in order to achieve success in resolving the air emergency.(AU)

Ethical Considerations of Climate Justice and International Air Travel in Short-Term Electives in Global Health.

In July 2022, the American Society of Tropical Medicine and Hygiene Green Task Force advocated to acknowledge the health impacts of climate change, particularly on those in low- and middle-income countries, and called on global health organizations to act. Simultaneously, academic medical centers are resuming Short-Term Electives in Global Health (STEGH) as travel restrictions imposed during the COVID-19 pandemic ease in most countries. International flights by trainees from academic medical centers in high-income countries (HIC) on these electives encapsulate the climate injustice of who generates carbon emissions and who bears the impacts of climate change. Using "decolonization" and "decarbonization" as guiding principles, we suggest several strategies that global medical education programs in HIC could implement. First, restructure rotations to halt STEGH with minimal benefit to host institutions, optimize trainee activities while abroad, and lengthen rotation duration. Second, programs can calculate the carbon impact of their STEGH and implement concrete measures to cut emissions. Finally, we urge academic medical centers to promote climate-resilient healthcare infrastructure in host countries and advocate for climate solutions on the global stage.

Influenza: seasonality and travel-related considerations.

RATIONALE FOR REVIEW: This review aims to summarize the transmission patterns of influenza, its seasonality in different parts of the globe, air travel- and cruise ship-related influenza infections and interventions to reduce transmission. KEY FINDINGS: The seasonality of influenza varies globally, with peak periods occurring mainly between October and April in the northern hemisphere (NH) and between April and October in the southern hemisphere (SH) in temperate climate zones. However, influenza seasonality is significantly more variable in the tropics. Influenza is one of the most common travel-related, vaccine-preventable diseases and can be contracted during travel, such as during a cruise or through air travel. Additionally, travellers can come into contact with people from regions with ongoing influenza transmission. Current influenza immunization schedules in the NH and SH leave individuals susceptible during their respective spring and summer months if they travel to the other hemisphere during that time. CONCLUSIONS/RECOMMENDATIONS: The differences in influenza seasonality between hemispheres have substantial implications for the effectiveness of influenza vaccination of travellers. Health care providers should be aware of influenza activity when patients report travel plans, and they should provide alerts and advise on prevention, diagnostic and treatment options. To mitigate the risk of travel-related influenza, interventions include antivirals for self-treatment (in combination with the use of rapid self-tests), extending the shelf life of influenza vaccines to enable immunization during the summer months for international travellers and allowing access to the influenza vaccine used in the opposite hemisphere as a travel-related vaccine. With the currently available vaccines, the most important preventive measure involves optimizing the seasonal influenza vaccination. It is also imperative that influenza is recognized as a travel-related illness among both travellers and health care professionals.