scholarly journals Effects of high altitude in pregnancy: an opportunity of research in KAHS

2018 ◽  
Vol 1 (3) ◽  
pp. 1-2
Author(s):  
Binod Aryal
Keyword(s):  
Birth Weight ◽  
South America ◽  
High Altitude ◽  
Work Performance ◽  
Arterial Oxygen Saturation ◽  
Functional Adaptation ◽  
European Ancestry ◽  
Arterial Oxygen ◽  
Adaptation To Hypoxia ◽  
Physiological Changes

Pregnancy is a special condition in a women’s life with unique physiological changes. There has been some research on physiological changes in human body in high altitude; however, there are many things still unknown about pregnancy at high altitude. It is an estimation that about 140 million people worldwide live in high altitude of above 2500 m, and it is believed that the hypobaric hypoxia of pregnancy at high altitude is the most common cause for maternofetal hypoxia. It has been seen that the babies born at high altitude are smaller, and the degree of smallness is inversely correlated with the number of generations of ancestors of high-altitude residence. Some studies show that women in populations with high-altitude ancestry, such as the Aymaras or Quechuas in South America and Tibetans in Asia, deliver heavier babies than women from European ancestry in South America or Han women in China living at high altitude. A study by Jensen and Moore shows that in Colorado, altitude acts as an independent factor in determining birth weight, with a reduction in birth weight of 100 g per 1000 m elevation gain. Studies have shown that low birth weight at high altitude has no association with socioeconomic status. Hence, it may reflect either hypoxia-induced intrauterine growth restriction or genetic adaptation. The latter implies a strong fetomaternal interaction involving adaptation to hypoxia on several levels. It also reflects the importance of interaction between the mother and the fetus which is stressed by the fact that better maternal ventilator response to hypoxic stress at high altitude correlates positively with birth weight. Another study shows that people living at altitudes of 4000 m and above have an arterial partial pressure of oxygen of 50 mmHg and an arterial oxygen saturation of just above 80%. There has been many studies on populations living in high-altitude regions for many generations, like Quechuas and Tibetans, which show many functional and structural adaptations in high altitude. This adaptation helps to allow for a way out for the main metabolic problem they face: maintaining an acceptably high scope for sustained aerobic metabolism despite reduced availability of oxygen in the inspired air. The functional adaptation to high altitude is measured indirectly by determining aerobic capacity, which reflects not only the maximum work performance but also the success of the individual’s biological oxygen transport system.

EGLN1 variants influence expression and SaO2 levels to associate with high-altitude pulmonary oedema and adaptation

2012 ◽  
Vol 124 (7) ◽  
pp. 479-489 ◽  
Author(s):  
Aastha Mishra ◽  
Ghulam Mohammad ◽  
Tashi Thinlas ◽  
M. A. Qadar Pasha
Keyword(s):  
High Altitude ◽  
Pulmonary Oedema ◽  
Oxygen Sensor ◽  
Arterial Oxygen Saturation ◽  
Systolic Pressure ◽  
Inverse Correlation ◽  
Functional Adaptation ◽  
Arterial Oxygen ◽  
Pulmonary Artery Systolic Pressure ◽  
Association Analyses

EGLN1 [encoding HIF (hypoxia-inducible factor)-prolyl hydroxylase 2] plays a pivotal role in the HIF pathway and has emerged as one of the most intriguing genes with respect to physiology at HA (high altitude). EGLN1, being an actual oxygen sensor, appears to have a potential role in the functional adaptation to the hypobaric hypoxic environment. In the present study, we screened 30 polymorphisms of EGLN1, evaluated its gene expression and performed association analyses. In addition, the role of allelic variants in altering TF (transcription factor)-binding sites and consequently the replacement of TFs at these loci was also investigated. The study was performed in 250 HAPE-p [HAPE (HA pulmonary oedema)-patients], 210 HAPE-f (HAPE-free controls) and 430 HLs (healthy Ladakhi highland natives). The genotypes of seven polymorphisms, rs1538664, rs479200, rs2486729, rs2790879, rs480902, rs2486736 and rs973252, differed significantly between HAPE-p and HAPE-f (P<0.008). The genotypes AA, TT, AA, GG, CC, AA and GG of rs1538664, rs479200, rs2486729, rs2790879, rs480902, rs2486736 and rs973252, prevalent in HAPE-p, were identified as risk genotypes and their counterpart homozygotes, prevalent in HLs, were identified as protective. EGLN1 expression was up-regulated 4.56-fold in HAPE-p (P=0.0084). The risk genotypes, their haplotypes and interacting genotypes were associated with up-regulated EGLN1 expression (P<0.05). Similarly, regression analysis showed that the risk alleles and susceptible haplotypes were associated with decreased SaO2 (arterial oxygen saturation) levels in the three groups. The significant inverse correlation of SaO2 levels with PASP (pulmonary artery systolic pressure) and EGLN1 expression and the association of these polymorphisms with SaO2 levels and EGLN1 expression contributed to uncovering the molecular mechanism underlying hypobaric hypoxic adaptation and maladaptation.

scholarly journals Spleen contraction elevates hemoglobin concentration at high altitude during rest and exercise

2020 ◽  
Vol 120 (12) ◽  
pp. 2693-2704
Author(s):  
Erika Schagatay ◽  
Alexander Lunde ◽  
Simon Nilsson ◽  
Oscar Palm ◽  
Angelica Lodin-Sundström
Keyword(s):  
High Altitude ◽  
Acute Hypoxia ◽  
Arterial Oxygen Saturation ◽  
Hemoglobin Concentration ◽  
Step Test ◽  
Arterial Oxygen ◽  
Spleen Volume ◽  
Spleen Contraction ◽  
Response To Exercise ◽  
Rest And Exercise

Abstract Purpose Hypoxia and exercise are known to separately trigger spleen contraction, leading to release of stored erythrocytes. We studied spleen volume and hemoglobin concentration (Hb) during rest and exercise at three altitudes. Methods Eleven healthy lowlanders did a 5-min modified Harvard step test at 1370, 3700 and 4200 m altitude. Spleen volume was measured via ultrasonic imaging and capillary Hb with Hemocue during rest and after the step test, and arterial oxygen saturation (SaO2), heart rate (HR), expiratory CO2 (ETCO2) and respiratory rate (RR) across the test. Results Resting spleen volume was reduced with increasing altitude and further reduced with exercise at all altitudes. Mean (SE) baseline spleen volume at 1370 m was 252 (20) mL and after exercise, it was 199 (15) mL (P < 0.01). At 3700 m, baseline spleen volume was 231 (22) mL and after exercise 166 (12) mL (P < 0.05). At 4200 m baseline volume was 210 (23) mL and after exercise 172 (20) mL (P < 0.05). After 10 min, spleen volume increased to baseline at all altitudes (NS). Baseline Hb increased with altitude from 138.9 (6.1) g/L at 1370 m, to 141.2 (4.1) at 3700 m and 152.4 (4.0) at 4200 m (P < 0.01). At all altitudes Hb increased from baseline during exercise to 146.8 (5.7) g/L at 1370 m, 150.4 (3.8) g/L at 3700 m and 157.3 (3.8) g/L at 4200 m (all P < 0.05 from baseline). Hb had returned to baseline after 10 min rest at all altitudes (NS). The spleen-derived Hb elevation during exercise was smaller at 4200 m compared to 3700 m (P < 0.05). Cardiorespiratory variables were also affected by altitude during both rest and exercise. Conclusions The spleen contracts and mobilizes stored red blood cells during rest at high altitude and contracts further during exercise, to increase oxygen delivery to tissues during acute hypoxia. The attenuated Hb response to exercise at the highest altitude is likely due to the greater recruitment of the spleen reserve during rest, and that maximal spleen contraction is reached with exercise.

P6480Asymmetric dimethylarginine (ADMA) predicts altitude-associated hypoxic pulmonary arterial hypertension

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
R H Boeger ◽  
P Siques ◽  
J Brito ◽  
E Schwedhelm ◽  
E Pena ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Logistic Regression ◽  
Oxygen Saturation ◽  
High Altitude ◽  
Sea Level ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Arterial Blood ◽  
Pulmonary Arterial

Abstract Prolonged exposure to altitude-associated chronic hypoxia (CH) may cause high altitude pulmonary hypertension (HAPH). Chronic intermittent hypobaric hypoxia (CIH) occurs in individuals who commute between sea level and high altitude. CIH is associated with repetitive acute hypoxic acclimatization and conveys the long-term risk of HAPH. As nitric oxide (NO) is an important regulator of systemic and pulmonary vascular tone and asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthesis that increases in hypoxia, we aimed to investigate whether ADMA predicts the incidence of HAPH among Chilean frontiers personnel exposed to six months of CIH. We performed a prospective study of 123 healthy male subjects who were subjected to CIH (5 days at appr. 3,550 m, followed by 2 days at sea level) for six months. ADMA, SDMA, L-arginine, arterial oxygen saturation, systemic arterial blood pressure, and haematocrit were measured at baseline and at months 1, 4, and 6 at high altitude. Acclimatization to high altitude was determined using the Lake Louise Score and the presence of acute mountain sickness (AMS). Echocardiography was performed after six months of CIH in a subgroup of 43 individuals with either good (n=23) or poor (n=20) aclimatization to altitude, respectively. Logistic regression was used to assess the association of biomarkers with HAPH. 100 study participants aged 18.3±1.3 years with complete data sets were included in the final analysis. Arterial oxygen saturation decreased upon the first ascent to altitude and plateaued at about 90% during the further course of the study. Haematocrit increased to about 47% after one month and remained stable thereafter. ADMA continuously increased and SDMA decreased during the study course, whilst L-arginine levels showed no distinct pattern. The incidence of AMS and the Lake Louise Score were high after the first ascent (53 and 3.1±2.4, respectively) and at one month of CIH (47 and 3.0±2.6, respectively), but decreased to 20 and 1.4±2.0 at month 6, respectively (both p<0.001 for trend). In echocardiography, 18 participants (42%) showed a mean pulmonary arterial pressure (mPAP) greater than 25 mm Hg (mean ± SD, 30.4±3.9 mm Hg), out of which 9 (21%) were classified as HAPH (mPAP ≥30 mm Hg; mean ± SD, 33.9±2.2 mm Hg). Baseline ADMA, but not SDMA, was significantly associated with mPAP at month 6 in univariate logistic regression analysis (R = 0.413; p=0.007). In ROC analysis, a cut-off for baseline ADMA of 0.665 μmol/l was determined as the optimal cut-off level to predict HAPH (mPAP >30 mm Hg) with a sensitivity of 100% and a specificity of 63.6%. ADMA concentration increases during long-term CIH. It is an independent predictive biomarker for the incidence of HAPH. SDMA concentration decreases during CIH and shows no association with HAPH. Our data support a role of impaired NO-mediated pulmonary vasodilation in the pathogenesis of high altitude pulmonary hypertension. Acknowledgement/Funding CONICYT/FONDEF/FONIS Sa 09I20007; FIC Tarapaca BIP 30477541-0; BMBF grant 01DN17046 (DECIPHER); Georg & Jürgen Rickertsen Foundation, Hamburg

scholarly journals Associations between arterial oxygen saturation, body size and limb measurements among high-altitude andean children

2013 ◽  
Vol 25 (5) ◽  
pp. 629-636 ◽  
Author(s):  
Emma Pomeroy ◽  
Jay T. Stock ◽  
Sanja Stanojevic ◽  
J. Jaime Miranda ◽  
Tim J. Cole ◽  
...  
Keyword(s):  
Body Size ◽  
Oxygen Saturation ◽  
High Altitude ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen

scholarly journals Pulmonary artery pressure and arterial oxygen saturation in people living at high or low altitude: systematic review and meta-analysis

2016 ◽  
Vol 121 (5) ◽  
pp. 1151-1159 ◽  
Author(s):  
Rodrigo Soria ◽  
Matthias Egger ◽  
Urs Scherrer ◽  
Nicole Bender ◽  
Stefano F. Rimoldi
Keyword(s):  
Systematic Review ◽  
Pulmonary Artery ◽  
Oxygen Saturation ◽  
High Altitude ◽  
Pulmonary Artery Pressure ◽  
Meta Analysis ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Low Altitude ◽  
Apparently Healthy

More than 140 million people are living at high altitude worldwide. An increase of pulmonary artery pressure (PAP) is a hallmark of high-altitude exposure and, if pronounced, may be associated with important morbidity and mortality. Surprisingly, there is little information on the usual PAP in high-altitude populations. We, therefore, conducted a systematic review (MEDLINE and EMBASE) and meta-analysis of studies published (in English or Spanish) between 2000 and 2015 on echocardiographic estimations of PAP and measurements of arterial oxygen saturation in apparently healthy participants from general populations of high-altitude dwellers (>2,500 m). For comparison, we similarly analyzed data published on these variables during the same period for populations living at low altitude. Twelve high-altitude studies comprising 834 participants and 18 low-altitude studies (710 participants) fulfilled the inclusion criteria. All but one high-altitude studies were performed between 3,600 and 4,350 m. The combined mean systolic PAP (right ventricular-to-right atrial pressure gradient) at high altitude [25.3 mmHg, 95% confidence interval (CI) 24.0, 26.7], as expected was significantly (P < 0.001) higher than at low altitude (18.4 mmHg, 95% CI 17.1,19.7), and arterial oxygen saturation was significantly lower (90.4%, 95% CI 89.3, 91.5) than at low altitude (98.1%; 95% CI 97.7, 98.4). These findings indicate that at an altitude where the very large majority of high-altitude populations are living, pulmonary hypertension appears to be rare. The reference values and distributions for PAP and arterial oxygen saturation in apparently healthy high-altitude dwellers provided by this meta-analysis will be useful to future studies on the adjustments to high altitude in humans.

scholarly journals Angiotensin-Converting Enzyme Genotype and Arterial Oxygen Saturation at High Altitude in Peruvian Quechua

2008 ◽  
Vol 9 (2) ◽  
pp. 167-178 ◽  
Author(s):  
Abigail W. Bigham ◽  
Melisa Kiyamu ◽  
Fabiola León-Velarde ◽  
Esteban J. Parra ◽  
Maria Rivera-Ch ◽  
...  
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Oxygen Saturation ◽  
High Altitude ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Converting Enzyme ◽  
Angiotensin Converting Enzyme Genotype

scholarly journals Physiological Changes at Altitude in Nonasthmatic and Asthmatic Subjects

2004 ◽  
Vol 11 (3) ◽  
pp. 197-199 ◽  
Author(s):  
Dianna Louie ◽  
Peter D Paré
Keyword(s):  
Peak Expiratory Flow ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Physiological Changes ◽  
High Altitudes ◽  
Exercise Challenge ◽  
Per Se ◽  
Expiratory Flow ◽  
Exercise Induced ◽  
Very High

Exercised-induced asthma is not due to exercise itself per se, but rather is due to cooling and/or drying of the airway because of the increased ventilation that accompanies exercise. Travel to high altitudes is accompanied by increased ventilation of cool, often dry, air, irrespective of the level of exertion, and by itself, this could represent an 'exercise' challenge for asthmatic subjects. Exercise-induced bronchoconstriction was measured at sea level and at various altitudes during a two-week trek through the Himalayas in a group of nonasthmatic and asthmatic subjects. The results of this study showed that in mild asthmatics, there was a significant reduction in peak expiratory flow at very high altitudes. Contrary to the authors' hypothesis, there was not a significant additional decrease in peak expiratory flow after exercise in the asthmatic subjects at high altitude. However, there was a significant fall in arterial oxygen saturation postexercise in the asthmatic subjects, a change that was not seen in the nonasthmatic subjects. These data suggest that asthmatic subjects develop bronchoconstriction when they go to very high altitudes, possibly via the same mechanism that causes exercise-induced asthma.

New insights into ocular blood flow at very high altitudes

2009 ◽  
Vol 106 (2) ◽  
pp. 454-460 ◽  
Author(s):  
Martina M. Bosch ◽  
Tobias M. Merz ◽  
Daniel Barthelmes ◽  
Benno L. Petrig ◽  
Frederic Truffer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
High Altitude ◽  
Cerebral Edema ◽  
Arterial Oxygen Saturation ◽  
Acute Mountain Sickness ◽  
Fundus Photography ◽  
Arterial Oxygen ◽  
High Altitudes ◽  
Choroidal Blood Flow

Little is known about the ocular and cerebral blood flow during exposure to increasingly hypoxic conditions at high altitudes. There is evidence that an increase in cerebral blood flow resulting from altered autoregulation constitutes a risk factor for acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) by leading to capillary overperfusion and vasogenic cerebral edema. The retina represents the only part of the central nervous system where capillary blood flow is visible and can be measured by noninvasive means. In this study we aimed to gain insights into retinal and choroidal autoregulatory properties during hypoxia and to correlate circulatory changes to symptoms of AMS and clinical signs of HACE. This observational study was performed within the scope of a high-altitude medical research expedition to Mount Muztagh Ata (7,546 m). Twenty seven participants underwent general and ophthalmic examinations up to a maximal height of 6,800 m. Examinations included fundus photography and measurements of retinal and choroidal blood flow, as well as measurement of arterial oxygen saturation and hematocrit. The initial increase in retinal blood velocity was followed by a decrease despite further ascent, whereas choroidal flow increase occurred later, at even higher altitudes. The sum of all adaptational mechanisms resulted in a stable oxygen delivery to the retina and the choroid. Parameters reflecting the retinal circulation and optic disc swelling correlated well with the occurrence of AMS-related symptoms. We demonstrate that sojourns at high altitudes trigger distinct behavior of retinal and choroidal blood flow. Increase in retinal but not in choroidal blood flow correlated with the occurrence of AMS-related symptoms.

Risk factors for high-altitude headache in mountaineers

Cephalalgia ◽  
2011 ◽  
Vol 31 (6) ◽  
pp. 706-711 ◽  
Author(s):  
Martin Burtscher ◽  
Klemens Mairer ◽  
Maria Wille ◽  
Gregor Broessner
Keyword(s):  
Risk Factors ◽  
High Altitude ◽  
Perceived Exertion ◽  
Medical Condition ◽  
Arterial Oxygen Saturation ◽  
Structured Interview ◽  
Arterial Oxygen ◽  
Caffeine Intake ◽  
High Prevalence ◽  
Study Participants

Aim: The aim was to identify most relevant risk factors of high-altitude headache within a broad mountaineering population through a prospective, observational, rater-blinded study. Methods: A total of 506 mountaineers were enrolled after their first overnight stay in one of seven alpine huts between 2200–3817 m. Structured interview including information on mountaineering histories, caffeine intake, smoking habits, alcohol consumption, intake of medication, rate of ascent, physical fitness, the level of exertion and the amount of fluids intake at the day of ascent were recorded along with a standardized medical examination. Results: High-altitude headache occurred in 31% of study participants. Logistic regression analysis revealed a migraine history, low arterial oxygen saturation, high ratings of perceived exertion and fluid intake below 2 l to be independent risk factors for the development of high-altitude headache. Conclusion: Given the high prevalence, high-altitude headache is a relevant medical condition and a better understanding of risk factors has important impact and may facilitate patient behaviour and future study design.

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