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BACKGROUND: In military aviation, due to high-altitude flight operations, hypoxia training is mandatory and nowadays is mainly done as normobaric hypoxia training in flight simulators. During the last decade, scientific data has been published about delayed recovery after normobaric hypoxia, known as a "hypoxia hangover." Sopite syndrome is a symptom complex that develops as a result of exposure to real or apparent motion, and it is characterized by yawning, excessive drowsiness, lassitude, lethargy, mild depression, and a reduced ability to focus on an assigned task. CASE REPORT: In this study, we present the case of a 49-yr-old pilot who participated in normobaric hypoxia refreshment training in an F/A-18C Hornet simulator and experienced delayed drowsiness, even 3 h after the training. DISCUSSION: This case report demonstrates the danger of deep hypoxia. Hypoxia training instructions should include restrictions related to driving a car immediately after hypoxia training. In addition, hypoxia may lower the brain threshold for sopite syndrome. Varis N, Leinonen A, Perälä J, Leino TK, Husa L, Sovelius R. Delayed drowsiness after normobaric hypoxia training in an F/A-18 Hornet simulator . Aerosp Med Hum Perform. 2023; 94(9):715-718.

INTRODUCTION: Physiological episodes are an issue in military aviation. Some non-pressure-related in-flight symptoms are proved to be due to hyperventilation rather than hypoxia. The aim of this study was to validate a new training method provoking hyperventilation during normobaric hypoxia (NH) training in an F/A-18 Hornet simulator. METHODS: In a double-blind setting, 26 fighter pilots from the Finnish Air Force performed 2 setups in a WTSAT simulator in randomized order with full flight gear. Without the pilot's knowledge, 6% O₂ in nitrogen or 6% O₂ + 4% CO₂ in nitrogen was turned on. Ventilation (VE) was measured before, during, and after hypoxia. S p o₂ and ECG were monitored and symptoms documented. The subjects performed a tactical identification flight until they recognized symptoms of hypoxia. Thereafter, they performed hypoxia emergency procedures with 100% O₂ and returned to the base with a GPS malfunction and executed an instrument landing system (ILS) approach with the waterline HUD mode evaluated by the flight instructor on a scale of 1 to 5. RESULTS: Ventilation increased during normobaric hypoxia (NH) from 12 L · min -1 to 19 L · min -1 at S p o₂ 75% with 6% O₂, and from 12 L · min -1 to 26 L · min -1 at S p o₂ 77% with 6% O₂ + 4% CO₂. ILS flight performance was similar 10 min after combined hyperventilation and hypoxia (3.1 with 6% O₂ + 4% CO₂ and 3.2 with 6% O₂). No adverse effects were reported during the 24-h follow-up. DISCUSSION: Hyperventilation-provoking normobaric hypoxia training is a new and well-tolerated method to meet NATO Standardization Agreement hypoxia training requirements. Leinonen AM, Varis NO, Kokki HJ, Leino TK. A new method for combined hyperventilation and hypoxia training in a tactical fighter simulator . Aerosp Med Hum Perform. 2022; 93(9):681-687.

Introduction: In military aviation during high-altitude operations, an oxygen or cabin pressure emergency can impair brain function and performance. There are variations in individuals' physiological responses to low partial pressure of oxygen and hypoxia symptoms can vary from one exposure to another. The aim of this study was to evaluate how normobaric hypoxia (NH) affects pilots' minute ventilation and 10 min afterwards on Instrument Landing System (ILS) flight performance in Hawk simulator during a tactical flight sortie. Methods: Fifteen volunteer fighter pilots from the Finnish Air Force participated in this double blinded, placebo controlled and randomized study. The subjects performed three flights in a tactical Hawk simulator in a randomized order with full flight gear, regulators and masks on. In the middle of the flight without the subjects' knowledge, 21% (control), 8% or 6% oxygen in nitrogen was turned on. Minute ventilation (VE) was measured before, during NH and after NH. Forehead peripheral oxygen saturation (SpO 2 ), wireless ECG and subjective symptoms were documented. The flights were conducted so that both subjects and flight instructors were blinded to the gas mixture. The pilots performed tactical maneuvers at simulated altitude of 20,000 ft or 26,000 ft until they recognized the symptoms of hypoxia. Thereafter they performed hypoxia emergency procedures with 100% oxygen and returned to base (RTB). During the ILS approach, flight performance was evaluated. Results: The mean VE increased during NH from 12.9 L/min (21% O2 on the control flight) to 17.8 L/min with 8% oxygen ( p < 0.01), and to 21.0 L/min with 6% oxygen ( p < 0.01). Ten minutes after combined hyperventilation and hypoxia, the ILS flight performance decreased from 4.4 (control flight) to 4.0 with 8% oxygen ( p = 0.16) and to 3.2 with 6% oxygen ( p < 0.01). A significant correlation (r = -0.472) was found between the subjects' VE during 6% oxygen exposure and the ILS flight performance. Discussion: Hyperventilation during NH has a long-lasting and dose-dependent effect on the pilot's ILS flight performance, even though the hypoxia emergency procedures are executed 10 min earlier. Hyperventilation leads to body loss of carbon dioxide and hypocapnia which may even worsen the hypoxia hangover., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Varis, Leinonen, Parkkola and Leino.)

BACKGROUND: Sinus barotraumas are a common condition in aviation medicine, sometimes compromising flight safety and even permanently grounding aircrew. Considering this and the ever-increasing amount of commercial aviation, a thorough examination is required. METHODS: In this survey study, an anonymous, electronic questionnaire was distributed to commercial aircrew of the three major commercial airlines operating in Finland ( N 3799), covering 93% of the target population (i.e., all commercial aircrew operating in Finland, N 4083). Primary outcomes were self-reported prevalence, clinical characteristics, and health and occupational effects of sinus barotraumas in flight. Secondary outcomes were adjusted odds ratios (OR) for frequency of sinus barotraumas with respect to possible risk factors. RESULTS: Response rate was 47% ( N 1789/3799), with 61% ( N 1088) of the respondents having experienced sinus barotraumas in flight. Of those affected, 59% had used medications, 18% had undergone surgical procedures, and 53% had been on sick leave due to sinus barotraumas (38% during the last year) in flight. Factors associated with sinus barotraumas were female sex [OR, 2.47; 95% confidence interval (CI) 1.354.50] and a high number of upper respiratory tract infections (3 vs. <3 URTIs/yr: OR, 3.61; 95% CI 2.654.93). CONCLUSION: Sinus barotraumas were reported by 61% of commercial aircrew. They caused an increased need for medications, otorhinolaryngology-related surgical procedures, and sickness absence from flight duty. The possible risk factors were female sex and a high number of URTIs/yr. Lindfors OH, Ketola KS, Klockars TK, Leino TK, Sinkkonen ST. Sinus barotraumas in commercial aircrew . Aerosp Med Hum Perform. 2021; 92(11):857-863 .