Hypoxia Symptoms Research Articles

Experience of prone position ventilation in clinical nursing application

To understand the effect of supine ventilation in clinical nursing. Application method: 15 cases of respiratory failure and ARDS patients in ICU of our department were treated with recumbent ventilation and nursing measures in recent two years. Effect evaluation: after treatment, 12 patients showed significant improvement of symptoms, and 9 patients were successfully transferred to the department for further treatment. Conclusion: supine ventilation can improve the patient's hypoxia symptoms, increase functional residual air volume, improve ventilation blood flow ratio, reduce mediastinal and cardiac pressure on the lungs, and improve the compliance of the thoracic cavity.

Hypoxia signature: A useful tool for hypoxia recognition among aircrew

Introduction: Hypoxia, often referred to as “silent killer,” a common aeromedical stressor in aviation, may have catastrophic events in-flight unless recognized well in time. On exposure to hypoxia, an individual manifests a specific spectrum of symptoms referred to as “hypoxia signature.” The present study was conducted to assess the manifestation of “hypoxia signature” on repeated exposure to simulated hypobaric hypoxia for its potential usage as a tool for hypoxia recognition. Material and Methods: Twenty-two healthy adult volunteers were subjected to a simulated altitude of 22,000 feet for a duration of 5 min in the hypobaric altitude chamber. The symptoms experienced by the participants at the said altitude were recorded using a questionnaire. The heart rate (HR) and oxygen saturation (SpO2) were recorded during the exposure. The hypoxia exposure was repeated two more times with a minimum interval of 3 weeks between each. Paired t-test was used to compare the mean values of physiological parameters (HR and SpO2) between ground level and 22000 feet recorded in all the three exposures. The hypoxia symptoms and their severity reported during the exposures were compared with those of recalled symptoms (reported after 3 weeks of exposure) using McNemar test and Wilcoxon Signed Rank test, respectively. Results: Paired t-test revealed a statistically significant increase in HR and fall in SpO2 with rise in altitude from ground level to 22000 feet. The three most common symptoms consistently observed were lightheadedness, thinking slow, and warm feeling. The common hypoxic symptoms and their severity scores reported at 22,000 feet compared with recalled counterpart during subsequent exposures did not reveal any significant differences (P > 0.05). Conclusion: There was a high degree of similarity in the frequency and severity score of symptoms between acute exposure to hypobaric hypoxia and recall indicating evidence of repeatability of symptoms across the three sessions of hypoxia exposure within the individuals. This brings out the usefulness of “hypoxia signature” as a tool for hypoxia recognition and its application in hypoxia indoctrination and training for aircrew.

Analysis of Altitude Hypoxia Training and In-Flight Hypoxia Events among the Helicopter Aircrews.

All aircrews are required to undertake the altitude hypoxia training and be familiarized with the hypobaric effect on their physiological regulation. Due to the characteristics of the helicopter aircrafts, few researches have reported in-flight hypoxia events among the helicopter aircrews. The main goal of this study was designed to compare the hypoxia symptoms of helicopter aircrews between the altitude hypoxia training and during flight. We developed a questionnaire to collect the details of chamber flights and in-flight hypoxia events in 2019. All data were managed by the SPSS software and two-tailed 0.05 alpha level was considered as a significant level. Of the 213 study participants, there were eight (3.8%) cases that experienced hypoxia symptoms during the flight. The top five symptoms that appeared both in the last and current altitude hypoxia trainings were visual impairment (20.7%), difficulty concentrating (12.7%), tiredness (12.2%), cognitive impairment (8.0%), and air hunger (5.2%). Meanwhile, the frequency of those symptoms above was not significantly different from the last or current training compared with those in-flight hypoxia events. The survey unveiled a series of consistency correlations of hypoxia symptoms between the chamber flights and in-flight environment for the helicopter aircrew group.

Exposure to hypoxia impairs helicopter pilots’ awareness of environment

The purpose of the present study was to determine how hypoxia effects awareness of environment (AoE) in helicopter pilots operating at high altitude. Eight helicopter crews flew two operational flights in a flight simulator while breathing gas mixtures of 20.9% (equivalent to 0 m altitude) and 11.4% (equivalent to 4572 m or 15,000 ft altitude) oxygen in a single blinded, counterbalanced, repeated measures study. Each flight included five missions, during which environment items were introduced that the crews needed to be aware of, and respond to. In the 4572 m simulation, the crews missed overall 28 AoE items compared to 12 in the 0 m simulation (Z = −1.992; p = .046). In contrast, the crews’ technical skills were not significantly effected by hypoxia. Remarkably, the majority of pilots did not notice they were hypoxic or recognise their hypoxia symptoms during the simulation flight at 4572 m. Practitioner summary We show that hypoxia has a detrimental effect on helicopter pilot’s AoE and alertness. This can lead to an increased risk for flight safety. To mitigate this risk we recommend performing hypoxia training in a flight simulator, developing wearable systems for physiological monitoring of pilots and re-evaluating current altitude regulations. Abbreviations: ANOVA: Analysis of variance; AoE: awareness of environment; CSV: comma-separated values; HDU: helmet display unit; HR: heart rate; IQR: interquartile range; Mdn: median; NTS: non-technical skills; RNLAF: Royal Netherlands Air Force; PPM: parts per million; SpO2: oxygen saturation; SSS: Stanford sleepiness scale; TS: technical Skills

Coronavirus disease 2019 in pregnant and non-pregnant women: a retrospective study.

Coronavirus disease 2019 in pregnant and non-pregnant women: a retrospective study.

Hypoxic Hypoxia and Brain Function in Military Aviation: Basic Physiology and Applied Perspectives.

Acute hypobaric hypoxia (HH) is a major physiological threat during high-altitude flight and operations. In military aviation, although hypoxia-related fatalities are rare, incidences are common and are likely underreported. Hypoxia is a reduction in oxygen availability, which can impair brain function and performance of operational and safety-critical tasks. HH occurs at high altitude, due to the reduction in atmospheric oxygen pressure. This physiological state is also partially simulated in normobaric environments for training and research, by reducing the fraction of inspired oxygen to achieve comparable tissue oxygen saturation [normobaric hypoxia (NH)]. Hypoxia can occur in susceptible individuals below 10,000 ft (3,048 m) in unpressurised aircrafts and at higher altitudes in pressurised environments when life support systems malfunction or due to improper equipment use. Between 10,000 ft and 15,000 ft (4,572 m), brain function is mildly impaired and hypoxic symptoms are common, although both are often difficult to accurately quantify, which may partly be due to the effects of hypocapnia. Above 15,000 ft, brain function exponentially deteriorates with increasing altitude until loss of consciousness. The period of effective and safe performance of operational tasks following exposure to hypoxia is termed the time-of-useful-consciousness (TUC). Recovery of brain function following hypoxia may also lag beyond arterial reoxygenation and could be exacerbated by repeated hypoxic exposures or hyperoxic recovery. This review provides an overview of the basic physiology and implications of hypoxia for military aviation and discusses the utility of hypoxia recognition training.

Decompression Illness Incidence and Hypoxia Symptoms After Prebreathing in Hypobaric Hypoxia Training.

INTRODUCTION: Hypobaric hypoxia training utilizing the environmental chamber is often preceded by prebreathing of 100% oxygen with the goal of reducing decompression illness (DCI). We aimed to study the impact of prebreathing 100% oxygen for 30 min prior to hypobaria exposure to 7600 m (25,000 ft) on the incidence rate of DCI, as well as the impact of prebreathing on hypoxia symptoms felt during training.METHODS: Records of participants who underwent hypobaric hypoxia training in the Republic of Singapore Air Force (RSAF) from 2011 to 2014 (before introduction of prebreathing) were compared to those who underwent similar training from 2014 to 2017 (after introduction of prebreathing) to determine the incidences of DCI for both groups. Participants who underwent hypobaric hypoxia training from January 2017 to July 2017 completed a survey to assess the impact of prebreathing on the presentation and severity of hypoxia symptoms.RESULTS: Two DCI events were recorded in 1530 hypobaric chamber exposures without prebreathing while two DCI events were recorded in 1729 exposures with prebreathing. There was no significant difference in the incidence of DCI between the two groups. The survey findings showed no significant difference in the presentation and severity of hypoxia symptoms with 30 min of prebreathing.DISCUSSION: Incidence of DCI remains low during hypobaric chamber training, with no statistical difference with or without prebreathing. Possible reasons were the short duration of hypobaric exposure of 10 min during hypoxia training, and that 30 min of prebreathing was insufficient to further decrease or eliminate the risk of DCI in short duration hypobaric exposures.Cheok LJ, Goh BLY, Soh FW, Chuan BTB. Decompression illness incidence and hypoxia symptoms after prebreathing in hypobaric hypoxia training. Aerosp Med Hum Perform. 2021; 92(5):289293.

Ecotoxicological effects of pyraclostrobin on tilapia (Oreochromis niloticus) via various exposure routes

Pyraclostrobin is a widely used and highly efficient fungicide that also has high toxicity to aquatic organisms, especially fish. Although some research has reported the toxic effects of pyraclostrobin on fish, the main toxic pathways of pyraclostrobin in fish remain unclear. The present study has integrated histopathological, biochemical and hematological techniques to reveal the main toxic pathways and mechanisms of pyraclostrobin under different exposure routes. Our results indicated that pyraclostrobin entered fish mainly through the gills. The highest accumulation of pyraclostrobin was observed in the gills and heart compared with accumulation in other tissues and gill tissue showed the most severe damage. Hypoxia symptoms (water jacking, tummy turning and cartwheel formation) in fish were observed throughout the experiment. Taken together, our results suggested that the gills are important target organs. The high pyraclostrobin toxicity to gills might be associated with oxidative damage to the gills, inducing alterations in ventilation frequency, oxygen-carrying substances in blood and disorders of energy metabolism. Our research facilitates a better understanding of the toxic mechanisms of pyraclostrobin in fish, which can promote the ecotoxicological research of agrochemicals on aquatic organisms.

Contributions of Hypoxia-Awareness Training to the Familiarization of Personal Symptoms for Occupational Safety in the Flight Environment.

Hypoxia remains a flight-safety issue in terms of aviation medicine. Hypoxia-awareness training has been used to help aircrew members recognize personal hypoxia symptoms. There is still no study, as yet, to establish the association of within-subject data between inflight hypoxia events and the altitude chamber. The main purpose of our study was to use paired subjects’ data on inflight hypoxia symptoms compared with those experienced during training. A questionnaire was developed to obtain information on military aircrew members in 2018. Among 341 subjects, 46 (13.49%) suffered from inflight hypoxia. The majority of the subjects detected ongoing inflight hypoxia on the basis of their previous experience with personal hypoxia symptoms or sensations in previous chamber flights. Of the top five hypoxia symptoms, the data revealed that hot flashes, poor concentration, and impaired cognitive function appeared both during the inflight events and during the hypoxia-awareness training. The occurrence rate of hypoxia symptoms was found to not be significantly different between the in-flight events and the past chamber flights through an analysis of within-subject data. Because the individual memory had faded away over time, fresher hypoxia awareness training is still mandatory and valuable to recall personal hypoxia experience for military aircrew members.

Effect of early oxygen therapy and antiviral treatment on disease progression in patients with COVID-19: A retrospective study of medical charts in China

BackgroundUntil now, no antiviral treatment has been proven to be effective for the coronavirus disease 2019 (COVID-19). The timing of oxygen therapy was considered to have a great influence on the symptomatic relief of hypoxemia and seeking medical intervention, especially in situations with insufficient medical resources, but the evidence on the timing of oxygen therapy is limited.Methods and findingsMedical charts review was carried out to collect the data of hospitalized patients with COVID-19 infection confirmed in Tongji hospital, Wuhan from 30th December 2019 to 8th March 2020. In this study, the appropriate timing of oxygen therapy and risk factors associated with severe and fatal illness were identified and the effectiveness of antivirus on disease progression was assessed. Among 1362 patients, the prevalence of hypoxia symptoms was significantly higher in those patients with severe and fatal illness than in those with less severe disease. The onset of hypoxia symptoms was most common in the second to third week after symptom onset, and patients with critical and fatal illness experienced these symptoms earlier than those with mild and severe illness. In multivariable analyses, the risk of death increased significantly when oxygen therapy was started more than 2 days after hypoxia symptoms onset among critical patients (OR, 1.92; 95%CI, 1.20 to 3.10). Compared to the critically ill patients without IFN-a, the patients who were treated with IFN-a had a lower mortality (OR, 0.60; 95%CI, 0.39 to 0.91).ConclusionsEarly initiation of oxygen therapy was associated with lower mortality among critical patients. This study highlighted the importance of early oxygen therapy after the onset of hypoxia symptoms. Our results also lend support to potentially beneficial effects of IFNα on critical illness.

Neuropsychiatric outcome in attempted hanging: A case report.

Factors involved in causation of death by hanging include carotid and vertebral artery occlusion, jugular venous compression, tracheal obstruction, stimulation of carotid sinuses, and the parasympathetic and sympathetic nervous systems.[1] Survivors of attempted hanging may manifest a range of neuropsychiatric sequelae. We report a young male who survived a suicidal attempt by hanging but had prominent neuropsychiatric sequelae. A 29-year-old male survivor of suicidal hanging was brought to the psychiatric outpatient unit with complaints of forgetfulness, persistent and pervasive low mood, decreased social interaction, reduced interest in work as well as his daily routine, and disturbed appetite. He did not remember the hanging incident and also the past year. About 4 years back, following a breakup with his girlfriend, he developed low mood, reduced interest in work as well as his daily routine, anhedonia, getting tired easily, disturbed sleep, pessimistic views of future, and ideas of hopelessness and worthlessness, and attempted suicide by drinking poison. Luckily, his mother found him in the act and stopped him. His family members got him married in the next three months, thinking that it would help him, but his condition worsened. He began consuming alcohol at the age of 20 year, but has been consuming daily for the past 3 years. One day, he came back home drunk, and after a minimal provocation by his mother, he went into his room and locked the door. Sensing it to be unusual, they went to the window and found him hanging by a ligature tied to the ceiling fan. The family members brought him down. He had turned blue and was gasping at the time of rescue and was admitted to a nearby hospital. He remained in coma for 72 h. There was no evidence of hypoxic/ischemic changes in the brain on neuroimaging. In the initial 3–4 days of regaining consciousness, he remained disoriented to time and place but recognized relatives who visited him. He did not remember the hanging episode as well as events of almost 6 months preceding the attempted suicide. One and a half years after the incident, antero/retrograde amnesia still persisted. Although he was able to take care of self, he lacked initiative, remained apathetic, had unprovoked anger outbursts, and occasionally wept profusely. On physical examination, icterus was present. Mental status examination revealed restricted affect, impaired immediate, recent and remote memory, poor attention span, impaired insight, and judgment. His mini mental status examination score was 20. Magnetic resonance imaging (MRI) brain revealed frontal lobe atrophy. His memory scores on verbal retention for dissimilar pairs, mental balance and visual retention to be in the lowest quartiles, a below-average performance quotient, and severe visuospatial disturbance. He was started on tablet mirtazapine 15 mg, which leads to improvement in his symptoms. At the time of presentation, the patient had apathetic behavior, retro/anterograde amnesia, and mood symptoms, which made it difficult to diagnose. MRI changes and history of alcohol further led to a diagnostic dilemma between primary amnesic syndrome versus Korsakoff's syndrome. Since the patient also had along term history of low mood symptoms, he showed a significant improvement after treatment with antidepressant. Soon after, his memory, low mood features, and social interaction improved. Thereafter, the final diagnosis was made as depression with pseudodementia. Coma of more than 24 h duration carries a risk of severe neuropsychiatric defect on recovery of consciousness. The greater the duration of unconsciousness, more is the chances of irreversible damage. Hanging leads to hypoxic /anoxic injury, due to obstruction of airway. Hanging also leads to ischemia, due to occlusion of blood flow and is significant in causing cerebralnecrosis.[23] Furthermore, there is a selective vulnerability in different brain regions to undergo hypoxic–ischemic injuries such as hippocampus, striatum, thalamus, globus pallidus, and third layer of cerebral cortex.[1] Survivors of cerebral anoxia due to suicidal hanging may present with diverse neurological deficits and psychiatric symptoms or syndromes such as acute and chronic amnestic syndromes, dementia, Korsakoff's syndrome, and even hysteria. An analysis of the neuropsychiatric features found in hanging survivors highlights the diagnostic difficulty, which may lead to hypoxic symptoms being misjudged for hysterical disturbance.[4] Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Normobaric hypoxia training in military aviation and subsequent hypoxia symptom recognition

Altitude hypoxia episodes are increasingly common in military aviation. Hypoxia training is mandatory for fighter pilots, but evidence-based data on the effects of training are scarce. The purpose of this study was to validate the normobaric hypoxia (NH) training effect. Data were collected from 89 pilots from the Finnish Air Force (FINAF). This survey was conducted in a tactical F/A-18C Hornet simulator in two sessions under normobaric conditions, in which the pilots performed flight missions and breathed 21% oxygen (O2) in nitrogen (N2), and blinded to the pilot, the breathing gas was changed to a hypoxic mixture containing either 8, 7 or 6% O2 in N2. The time taken to notice hypoxia symptoms and peripheral capillary O2 saturation was measured. A mean of 2.4 years after the initial training, pilots recognised their hypoxic symptoms 18 s quicker with 8% O2 mixture, 20 s quicker with 7% O2 and 10 s quicker with 6% O2. Our data indicate that NH training in a flight simulator helps pilots to recognise hypoxia symptoms earlier, and may, thus, enhance flight safety. Practitioner Summary: We show that hypoxia training enhances pilots’ ability to recognise symptoms of acute normobaric hypoxic exposure up to 2.4 years after an initial NH training session. Based on these data, refreshment NH training is nowadays mandatory every 3 years in the FINAF as opposed to the North Atlantic Treaty Organisation (NATO) Standardisation Agreement (STANAG) requirement of 5-year intervals between hypoxia trainings. Abbreviations: O2: oxygen; TUC; time of usefull consciousness; SpO2: peripheral capillary oxygen saturation; NATO: North Atlantic Treaty Organization; STANAG: stanrdization agreement; HH: hypobaric hypoxia; NH: normobaric hypoxia; FINAF: finnish air force; N2: nitrogen; ECG: electrocardiogram; CI: confidence interval; SD: standard deviation

Psychophysiological Responses of Pilots in Hypoxia Training at 7000 and 7500 m.

INTRODUCTION: We compared the physiological responses, psychomotor performances, and hypoxia symptoms between 7000 m and 7500 m (23,000 and 24,600 ft) exposure to develop a safer hypoxia training protocol.METHODS: In altitude chamber, 66 male pilots were exposed to 7000 and 7500 m. Heart rate and arterial oxygen saturation were continuously monitored. Psychomotor performance was assessed using the computational task. The hypoxic symptoms were investigated by a questionnaire.RESULTS: The mean duration time of hypoxia was 323.0 56.5 s at 7000 m and 218.2 63.3 s at 7500 m. The 6-min hypoxia training was completed by 57.6% of the pilots and 6.1% of the pilots at 7000 m and at 7500 m, respectively. There were no significant differences in pilots heart rates and psychomotor performance between the two exposures. The Spo₂ response at 7500 m was slightly severer than that at 7000 m. During the 7000 m exposure, pilots experienced almost the same symptoms and similar frequency order as those during the 7500 m exposure.CONCLUSIONS: There were concordant symptoms, psychomotor performance, and very similar physiological responses between 7000 m and 7500 m during hypoxia training. The results indicated that 7000-m hypoxia awareness training might be an alternative to 7500-m hypoxia training with lower DCS risk and longer experience time.Wen D, Tu L, Wang G, Gu Z, Shi W, Liu X. Psychophysiological responses of pilots in hypoxia training at 7000 and 7500 m. Aerosp Med Hum Perform. 2020; 91(10):785789.

Comparison of hypobaric hypoxia symptoms between a recalled exposure and a current exposure.

BackgroundAircrew members are required to attend hypoxia awareness training regularly to strengthen their memory of their personal hypoxia symptoms by undergoing training inside a hypobaric chamber. The aim of this study was to examine the association between hypoxia symptoms experienced during two training sessions that were 4 years apart.MethodsThis was a crossover study to compare hypoxia symptoms and self-reported physiological effects of trapped gas between a previous training session and a current training session in an altitude chamber. The subjects were military crew members who undertook a 25,000-feet refresher training course in 2018. We used a structured questionnaire to obtain the target information before and during hypoxia exposure. Data were analyzed using SPSS software.ResultsA total of 341 trainees participated in this survey and completely filled out the questionnaire. Gastrointestinal tract discomfort caused by the expansion of trapped gas was the main physiological reaction during the previous and current training sessions. Frequently reported symptoms were poor concentration (30.5%), impaired cognitive function (20.5%), visual disturbances (16.4%), hot flashes (15.8%), and paresthesia (12.6%) during both exposures. However, the proportions of participants reporting poor concentration (P = 0.378) and visual disturbances (P = 0.594) were not significantly different between the recalled and current training sessions. The five most common symptoms among the subjects with less than 1,000 flight hours were poor concentration (29.8%), visual disturbance (27.3%), impaired cognitive function (14.9%), dizziness/lightheadedness (11.6%), and hot flashes (9.9%), which overlapped substantially with the symptoms reported by other subjects. The occurrence of those five most common symptoms in the group with more than 1,000 flight hours did not significantly differ between the recalled training session and the current training session.ConclusionsThe most common hypoxia symptoms reported were similar between the recalled and current training sessions in an environment with a low oxygen concentration. This finding was also clearly affected by the duration of flight experience. Moreover, GI effects of the expansion of trapped gas were commonly observed at low atmospheric pressure.

Application of rapid induction of intubation by sedatives combined with cis-atracurium in the emergency department

Objective To study the effect of sedative combined with cis-atracurium in rapid induction intubation in emergency department. Methods From October 15, 2017 to April 15, 2019, 52 critically ill patients who needed tracheal intubation in emergency department of the People's Hospital of Changzhi were selected.And the patients were numbered according to the time sequence of enrollment, and then randomly divided into group A and group B according to the random number table, with 26 cases in each group.Group A was given sedatives combined with cis-atracurium to induce rapid intubation.Group B only received sedatives to induce intubation.The success rate of intubation, successful intubation time were compared between the two groups.Before and after endotracheal intubation, the heart rate, mean arterial blood pressure, pulse oxygen concentration and the change of catecholamine concentration were compared. Results The success rate of intubation in group A was 100.0%, which in group B was 76.9%, the difference between the two groups was statistically significant (χ2=12.15, P 0.05). The serum adrenaline level was higher compared with before intubation, but there was no statistically significant difference (t=-1.03, P>0.05). In group B, the pulse oxygen concentration was significantly increased after intubation compared with before intubation (t=5.74, P 0.05). Conclusion In the airway management of critically ill patients in emergency department, the application of sedatives combined with cis-atracurium to rapidly induce intubation can improve the hypoxia symptoms of patients more rapidly and can keep patients' hemodynamics, catecholamine concentration is relatively stable, it has the characteristics of safety and efficiency. Key words: Emergency service, hospital; Emergencies; Critical illness; Airway management; Intubation, intratracheal; Atracurium; Hypnotics and sedatives; Hemodynamics

Chronic decompression illness cognitive dysfunction improved with hyperbaric oxygen: a case report

Altitude chamber exposures are used for training to allow aircrew to experience their hypoxia and pressure effect symptoms. Decompression illness (DCI) can occur subsequent to altitude chamber training or in operational aircraft when the cabin altitude is at least 18,000 feet. Definitive emergent treatment is hyperbaric oxygen (HBO2) to decrease bubble size, dissipate excess nitrogen, hyperoxygenate tissue and reduce inflammation. A 27-year-old female underwent altitude chamber training to 25,000 feet. She developed tingling in both legs and left arm, headache, dizziness, malaise, then difficulty talking. She underwent two HBO2 treatments. Over the next 12 months, she had paresthesia, decreased memory and cognitive function similar to symptoms seen following traumatic brain injury. She was referred 14 months after the event for evaluation. Using pre-deployment Automated Neuropsychological Assessment Metrics (ANAM) and serial tests over 58 HBO2 treatments, the patient demonstrated near-return to her pre-deployment test scores.. The reason for HBO2 treatment was based on previous experience with chronic traumatic brain injury subjects where HBO2 improved outcome. The patient's chronic neurological symptoms mimicked chronic TBI. The patient was unique in that baseline cognitive tests existed that could be used to monitor her changes during the treatment series.

Abstract P194: Endothelin as a Persistent Biomarker of Hypoxia

Rationale: Hypoxic symptoms at moderate altitude are not well characterized. Hypoxia can cause cognitive impairment, temporarily affecting the performance of aircrew, ground soldiers or other critical workers. Therefore, there is a need to determine if an individual has experienced asymptomatic hypoxemia after exposure to high altitude. Goal: To identify reliable blood biomarkers that are quickly modified by hypoxia which correlate with blood gases and cardiac-hemodynamic parameters. Plasma endothelin-1 [ET-1]p was initially investigated as a potential biomarker due to its upregulation by hypoxia. Methods: Mean arterial pressure (MAP), heart rate (HR) and electrocardiogram (ECG) were wirelessly recorded in conscious rats during exposure. Blood was obtained from rats exposed to normoxia (21% O 2 ) or hypoxia (12% O 2 ) after 0.5, 1, 6, or 24 hours. [ET-1] p level was assessed by ELISA. Results: MAP and HR increased after 6 hrs of hypoxia. PR interval of the ECG progressively increased in hypoxic rats correlating with the decrease in HR. Low frequency/high frequency (LF/HF) component of HR variability (HRV) decreased only after 30 min of hypoxia suggesting early parasympathetic effects. [ET-1] p increased after 1-24 hrs of hypoxia. [ET-1] p negatively correlated with Pa O2 , Pa CO2 , HCO 3 - , MAP and HR, but positively with LF (baroreceptor band) and HF (respiratory band). These results suggest hypoxia rapidly increases [ET-1] p , which may contribute to restoration of MAP. Conclusions: Our data suggest that ET-1 is a reliable hypoxia biomarker. Future studies will determine other potential biomarkers and for how long ET-1 remains elevated after returning to normoxia.

Hypoxia Hangover and Flight Performance After Normobaric Hypoxia Exposure in a Hawk Simulator.

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.

An Elusive Case of Acute Interstitial Pneumonia

Acute interstitial pneumonia (AIP) is a rare and severe form of diffuse lung injury that affects previously healthy individuals. It is a subset of idiopathic lung disease with a rapidly progressive course. The prognosis is poor with over 50% of patients dying during hospital admission from progressive respiratory failure. Presented herein is a case of a previously healthy 64-year-old woman without a prior history of tobacco use who presented with progressive hypoxia, dyspnea, and nonspecific constitutional symptoms.

The Anti-depression Effect of Angelicae Sinensis Radix Is Related to the Pharmacological Activity of Modulating the Hematological Anomalies.

Angelicae Sinensis Radix (AS), a well-known herb in traditional Chinese medicine (TCM), has been wildly used for replenishing the blood and promoting circulation, in Asia for thousands of years. It has been confirmed that AS also possesses the pharmacological activity of anti-depression. At the same time, recent studies suggested that depression is associated with anemia, and depression could be ameliorated via modulating the blood system. However, it is still unknown whether the anti-depression effect of AS is related to its pharmacological activity of modulating the blood system. In the current study, hematological examination and metabonomic techniques were performed to explore potential anti-depression mechanisms of AS, related to the function of modulating the blood system in a chronic unpredictable mild stress (CUMS) model. The results demonstrated that AS could significantly improve CUMS-induced depressive symptom, hematological anomalies, and hypoxia symptoms. The analysis of metabonomics demonstrated that 26 potential biomarkers in depression could be regulated by the administration of AS. Among them, eight biomarkers participate in the metabolic pathways of amino acid and sphingolipid, and energy metabolism could also be regulated in an anemia model through the administration of AS, as reported in previous literatures. Further results proved that AS modulated energy metabolism in depression through the inhibition of the expression of pyruvate dehydrogenase lipoamide kinase isozyme 1 (PDK-1) and lactate dehydrogenase A (LDHA). These results suggested that the modulation of the blood system was involved in the anti-depression effect of AS. The mechanism may be associated with the promotion of the body’s energy metabolism, the stabilization of cell membranes, the promotion of serum protein synthesis, and the enhancement of immunity.