Oculometric Feature Changes During Acute Hypoxia in a Simulated High-Altitude Airdrop Scenario

2021 ◽  
Vol 92 (12) ◽  
pp. 928-936
Author(s):  
Gaurav N. Pradhan ◽  
William Ottestad ◽  
Anders Meland ◽  
Jan Ivar Kåsin ◽  
Lars Øivind Høiseth ◽  
...  

BACKGROUND: Severe acute hypoxia results in a rapid deterioration of cognitive functioning and thus poses a risk for human operations in high altitude environments. This study aimed at investigating the effects of oxygen system failure during a high-altitude high-opening (HAHO) parachute jump scenario from 30,000 ft (9144 m) on human physiology and cognitive performance using a noncontact eye-tracking task.METHODS: Nine healthy male volunteers (ages 27–48) were recruited from the Norwegian Special Operations Commandos. Eye-tracking data were collected to derive information on cognitive performance in the context of rapid dynamic changes in pressure altitude while performing a modified King-Devick test. The baseline data was collected at 8000 ft (2438 m) while breathing 100% oxygen during decompression. For every test, the corresponding arterial blood gas analysis was performed.RESULTS: The study subjects endured severe hypoxia, which resulted in significant prolongations of fixation time (range: 284.1–245.6 ms) until 23,397 ft (131 m) and fixation size (range: 34.6–32.4 mm) until 25,389 ft (7739 m) as compared to the baseline (217.6 ± 17.8 ms and 27.2 ± 4.5 mm, respectively). The increase in the saccadic movement and decrease in the saccadic velocity was observed until 28,998 ft and 27,360 ft (8839 and 8339 m), respectively.DISCUSSION: This is the first study to investigate cognitive performance from measured oculometric variables during severe hypobaric hypoxia in a simulated high-altitude airdrop mission scenario. The measurement of altered oculometric variables under hypoxic conditions represents a potential avenue to study altered cognitive performance using noncontact sensors that can derive information and serve to provide the individual with a warning from impending incapacitation.Pradhan GN, Ottestad W, Meland A, Kåsin JI, Høiseth LØ, Cevette MJ, Stepanek J. Oculometric feature changes during acute hypoxia in a simulated high-altitude airdrop scenario. Aerosp Med Hum Perform. 2021; 92(12):928–936.

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xiaozheng Wu ◽  
Wen Li ◽  
Zhenliang Luo ◽  
Yunzhi Chen

Objective. To systematically review the efficacy and safety of Ligustrazine in the treatment of idiopathic pulmonary fibrosis (IPF). Methods. The electronic literature databases (PubMed, EMbase, CNKI, WanFang database, and VIP) were retrieved through a computer to find out the randomized controlled trials (RCT) of Ligustrazine in the treatment of IPF according to the inclusion/exclusion criteria screening test. Cochrane’s bias risk table was also used to evaluate the quality of the study and to extract effective data. RevMan 5.3 was used for statistical analysis. Results. A total of 7 RCTs (a total of 366 patients, including 196 in experimental and 170 in control group). Compared with the control group, Ligustrazine could improve the clinical symptoms ([OR] = 2.20, 95% CI [1.40, 3.46], P = 0.0006 ), lung function (VC % [MD] = 3.92, 95% CI [0.68, 7.17], P = 0.02 ), (TLC% [MD] = 4.94, 95% CI [0.37, 9.52], P = 0.03 ), the pulmonary diffusion function (DLCO % [MD] = 9.12, 95% CI [5.70, 12.55], P < 0.00001 ), and arterial blood gas analysis (PaO2 [MD] = 7.11, 95% CI [1.96, 12.25], P = 0.007 ) (PaCO2 [MD] = −2.42, 95% CI [−4.36, −0.49], P = 0.01 ) of IPF patients, respectively. However, FEV1/FVC % ([MD] = 9.37, 95% CI [−1.23, 19.97], P = 0.08 ) and adverse reactions ([MD] = 0.35, 95% CI [0.02, 5.36], P = 0.45 ) were not significantly improved. Conclusion. Ligustrazine has certain clinical efficacy in the treatment of IPF, but the safety of applying it and the adverse reactions need to be further analyzed and determined. It can be considered as a new alternative and complementary medicine to be promoted and recommended for use in medical units in various countries in the world and it solved the difficult problem of conventional drug treatment of IPF; therefore, more research strength can be put in the treatment of the pathological mechanism of IPF for further exploration. The study was registered under registration number CRD42020193626.


2017 ◽  
Vol 123 (6) ◽  
pp. 1443-1450 ◽  
Author(s):  
William Ottestad ◽  
Tor Are Hansen ◽  
Gaurav Pradhan ◽  
Jan Stepanek ◽  
Lars Øivind Høiseth ◽  
...  

High-Altitude High Opening (HAHO) is a military operational procedure in which parachute jumps are performed at high altitude requiring supplemental oxygen, putting personnel at risk of acute hypoxia in the event of oxygen equipment failure. This study was initiated by the Norwegian Army to evaluate potential outcomes during failure of oxygen supply, and to explore physiology during acute severe hypobaric hypoxia. A simulated HAHO without supplemental oxygen was carried out in a hypobaric chamber with decompression to 30,000 ft (9,144 m) and then recompression to ground level with a descent rate of 1,000 ft/min (305 m/min). Nine subjects were studied. Repeated arterial blood gas samples were drawn throughout the entire hypoxic exposure. Additionally, pulse oximetry, cerebral oximetry, and hemodynamic variables were monitored. Desaturation evolved rapidly and the arterial oxygen tensions are among the lowest ever reported in volunteers during acute hypoxia. PaO2 decreased from baseline 18.4 (17.3–19.1) kPa, 138.0 (133.5–143.3) mmHg, to a minimum value of 3.3 (2.9–3.7) kPa, 24.8 (21.6–27.8) mmHg, after 180 (60–210) s, [median (range)], N = 9. Hyperventilation with ensuing hypocapnia was associated with both increased arterial oxygen saturation and cerebral oximetry values, and potentially improved tolerance to severe hypoxia. One subject had a sharp drop in heart rate and cardiac index and lost consciousness 4 min into the hypoxic exposure. A simulated high-altitude airdrop scenario without supplemental oxygen results in extreme hypoxemia and may result in loss of consciousness in some individuals. NEW & NOTEWORTHY This is the first study to investigate physiology and clinical outcome of oxygen system failure in a simulated HAHO scenario. The acquired knowledge is of great value to make valid risk-benefit analyses during HAHO training or operations. The arterial oxygen tensions reported in this hypobaric chamber study are among the lowest ever reported during acute hypoxia.


1985 ◽  
Vol 32 (2) ◽  
pp. 112-118
Author(s):  
Seong Gyu Hwang ◽  
Su Taik Uh ◽  
Byung Soo Ahn ◽  
Dong Cheul Han ◽  
Choon Sik Park ◽  
...  

2017 ◽  
Vol 32 (2) ◽  
pp. 148-153
Author(s):  
Asifa Karamat ◽  
Shazia Awan ◽  
Muhammad Ghazanfar Hussain ◽  
Fahad Al Hameed ◽  
Faheem Butt ◽  
...  

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