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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.

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 .

BACKGROUND: Middle ear (ME) barotraumas are the most common condition in aviation medicine, sometimes seriously compromising flight safety. Considering this and the ever-increasing amount of commercial aviation, a detailed overview is warranted. 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 ME barotraumas in flight. Secondary outcomes were adjusted odds ratios (OR) for frequency of ME barotraumas with respect to possible risk factors. RESULTS: Response rate was 47% ( N 1789/3799), with 85% ( N 1516) having experienced ME barotraumas in flight. Of those affected, 60% had used medications, 5% had undergone surgical procedures, and 48% had been on sick leave due to ME barotraumas (40% during the last year). Factors associated with ME barotraumas included a high number of upper respiratory tract infections [3 URTIs/yr vs. 0 URTIs/yr: OR, 9.02; 95% confidence interval (CI) 3.9920.39] and poor subjective performance in Valsalva (occasionally vs. always successful: OR, 7.84; 95% CI 3.9715.51) and Toynbee (occasionally vs. always successful: OR, 9.06; 95% CI 2.6730.78) maneuvers. CONCLUSION: ME barotraumas were reported by 85% of commercial aircrew. They lead to an increased need for medications, otorhinolaryngology-related surgical procedures, and sickness absence from flight duty. Possible risk factors include a high number of URTIs and poor performance in pressure equalization maneuvers. Lindfors OH, Ketola KS, Klockars TK, Leino TK, Sinkkonen ST. Middle ear barotraumas in commercial aircrew. Aerosp Med Hum Perform. 2021; 92(3):182189.

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.

Background: The present study aimed to find out if possible differences in early military flight career +Gz exposure level could predict permanent flight duty limitations (FDL) due to spinal disorders during a pilot's career., Methods: The study population consisted of 23 pilots flying with Gz limitation (max limitation ranging from +2 Gz to +5 Gz) due to spinal disorders and 50 experienced (+1000 flight hours) symptomless controls flying actively in operative missions in the Finnish Air Force. Data obtained for all subjects included the level of cumulative Gz exposure measured sortie by sortie with fatigue index (FI) recordings and flight hours during the first 5 yr of the pilot's career., Results: The mean (± SD) accumulation of FI in the first 5 yr of flying high-performance aircraft was 8.0 ± 1.8 among the pilots in the FDL group and 7.7 ± 1.7 in the non-FDL group. There was no association between flight duty limitations and early career cumulative +Gz exposure level measured with FI or flight hours., Discussion: According to the present findings, it seems that the amount of cumulative +Gz exposure during the first 5 yr of a military pilot's career is not an individual risk factor for spinal disorders leading to flight duty limitation. Future studies conducted with FI recordings should be addressed to reveal the relationship between the actual level of +Gz exposure and spinal disorders, with a longer follow-up period and larger sample sizes.Honkanen T, Sovelius R, Mäntysaari M, Kyröläinen H, Avela J, Leino TK. +Gz exposure and spinal injury-induced flight duty limitations. Aerosp Med Hum Perform. 2018; 89(6):552-556.

Introduction: Radio communication remains important for the delivery of safety-critical information in military aviation. Pilots are exposed to high noise levels. Noise attenuation provided by certain helmets is not sufficient, and resulting noise exposure can deteriorate operational effectiveness and flight safety. A need for hearing protection that enables efficient communication is obvious, especially for fighter and helicopter pilots. One possible solution for this issue is molded communication earplugs (m-CEP). Data about the advantages and disadvantages of m-CEPs are limited., Methods: To determine the usage rates, advantages, disadvantages and pilot opinions about m-CEPs, an anonymous survey study including 31 questions was conducted in fighter, fighter trainer, helicopter, and transport aircraft units of the Finnish Defense Forces., Results: Of the pilots who responded, 136 (93%) had used or tried m-CEPs and 90 (62%) were currently using them. There are many benefits to m-CEPs: they seem to enhance experienced speech intelligibility, since 85% of the pilots who had experience about them reported improved speech intelligibility under difficult hearing conditions, and 93% would recommend them to other pilots. It seems m-CEPs provide equal benefits to pilots with and without current hearing problems. They were also considered better than previously used hearing protectors. Still, problems were common: 82% of the pilots reported m-CEP related drawbacks, of which technical problems and discomfort issues were the most prevalent., Discussion: Most military pilots hold a positive opinion on m-CEPs and are willing to recommend their use. Technical problems and discomfort issues are, however, relatively common.