Feet In Altitude Research Articles

The Impact of Altitude Training on NCAA Division I Female Swimmers’ Performance

In this study, we investigate the effects of altitude training on female swimmers prior to college and how that training ultimately affects perfor- mance in their college career. In particular, for female athletes training in college at altitudes above 5,000 feet, we test whether athletes that trained at altitudes above 5,000 feet prior to college had different time drops between collegiate and high school best times, compared to athletes whose pre-collegiate training was below 5,000 feet. We test the hypothesis that having trained in college at altitudes above 5,000 feet and training prior to college at altitudes above 5,000 feet compared to altitudes below 5,000 feet will result in different observed time drops between collegiate and high school best times. We considered swimmers from four NCAA Division I colleges located in Colorado at altitudes ranging from approximately 5,000 to 7,000 feet above sea level. We collected data on the best pre- collegiate and collegiate times of 167 sprint event (50 freestyle) swimmers, 164 middle-distance event (200 freestyle) swimmers, and 69 distance event (1650 freestyle) swimmers. The subjects were grouped by event specialty and whether or not they trained at altitude prior to their collegiate careers. Time improvements from best pre-collegiate times to best collegiate times between altitude groupings were computed for swimmers and event groups. We conclude that there is no significant drop in time between swimmers who swam at below 5,000 feet in altitude prior to their collegiate careers and those who swam at or above 5,000 feet in altitude.

Correlation of ECG changes at high altitude with findings on Coronary Angiogram.

Objective: To highlight association of coronary artery disease on angiograms and high altitude-related ECG abnormalities that is thought to be ischemic in origin.
 Place and Duration of Study: This was a cross sectional study done in Armed Force Institute of Cardiology/National Institute of Heart Disease from Oct 2016 to Oct 2021.
 Methodology: This was a cross sectional study done in AFIC/NIHD from Oct 2016–Oct 2021 (5years). A total of 103 patients at a range of 9000 to 22000 feet in altitude, with new ECG changes were selected via consecutive sampling. Data was analyzed by SPSS version-23. Descriptive statistics were run to present categorical data in frequencies and percentages. Chi-square and Fisher Exact Test was applied to find the association between study variables at 95% CI and 5% margin of error (α= 5%).
 Results: The data was collected from a total of 103 respondents, mean age (years) of the respondents was 30.57±6.27, and mean duration of stay (days) at high altitude was 64.8±68.3 (Table-I). ECG changes that were recorded were: T-wave inversion in anterior leads (V1, V2, V3) were reported in n=33(32%), T- wave inversion in Inferior leads (II, III, aVF) in 21(20.3%), T-wave inversion in lateral leads (V3-V6) 10(9.7%). Normal Ejection fraction was observed in 97% of the study participants while only 3% had mild left ventricular systolic impairment. Angiographic findings were found to be normal in n=92 (89.30%), minor coronary artery disease (CAD) in n=9 (8.70%), muscle bridge in LAD in n=2 (1.90%). Our results also showed that amongst other final diagnosis, of note were vasovagal syncope (n=5; 4.8%), pulmonary embolism (n=5; 4.8%) and pulmonary arterial hypertension (n=3; 2.9%).
 Conclusion: Our work leads us to the conclusion that ECG abnormalities at high altitude do not indicate coronary artery disease since they do not reflect a delay in electrical conduction or ischemia. These patients should be treated separately based on their high altitude disease symptoms (HAI).

Variability in venous gas emboli following the same dive at 3,658 meters

Update: originally posted in Vol 48 #2 Exposure to a reduction in ambient pressure such as in high-altitude climbing, flying in aircrafts, and decompression from underwater diving results in circulating vascular gas bubbles (i.e., venous gas emboli [VGE]). Incidence and severity of VGE, in part, can objectively quantify decompression stress and risk of decompression sickness (DCS) which is typically mitigated by adherence to decompression schedules. However, dives conducted at altitude challenge recommendations for decompression schedules which are limited to exposures of 10,000 feet in the U.S. Navy Diving Manual (Rev. 7). Therefore, in an ancillary analysis within a larger study, we assessed the evolution of VGE for two hours post-dive using echocardiography following simulated altitude dives at 12,000 feet. Ten divers completed two dives to 66 fsw (equivalent to 110 fsw at sea level by the cross correction method) for 30 minutes in a hyperbaric chamber. All dives were completed following a 60-minute exposure at 12,000 feet. Following the dive, the chamber was decompressed back to altitude for two hours. Echocardiograph measurements were performed every 20 minutes post-dive. Bubbles were counted and graded using the Germonpré and Eftedal and Brubakk method, respectively. No diver presented with symptoms of DCS following the dive or two hours post-dive at altitude. Despite inter- and intra-diver variability of VGE grade following the dives, the majority (11/20 dives) presented a peak VGE Grade 0, three VGE Grade 1, one VGE Grade 2, four VGE Grade 3, and one VGE Grade 4. Using the cross correction method for a 66-fsw dive at 12,000 feet of altitude resulted in a relatively low decompression stress and no cases of DCS.

Variability in venous gas emboli following the same dive at 3,658 meters

Exposure to a reduction in ambient pressure such as in high-altitude climbing, flying in aircrafts, and decompression from underwater diving results in circulating vascular gas bubbles (i.e., venous gas emboli [VGE]). Incidence and severity of VGE, in part, can objectively quantify decompression stress and risk of decompression sickness (DCS) which is typically mitigated by adherence to decompression schedules. However, dives conducted at altitude challenge recommendations for decompression schedules which are limited to exposures of 10,000 feet in the U.S. Navy Diving Manual (Rev. 7). Therefore, in an ancillary analysis within a larger study, we assessed the evolution of VGE for two hours post-dive using echocardiography following simulated altitude dives at 12,000 feet. Ten divers completed two dives to 66 fsw (equivalent to 110 fsw at sea level by the cross correction method) for 30 minutes in a hyperbaric chamber. All dives were completed following a 60-minute exposure at 12,000 feet. Following the dive, the chamber was decompressed back to altitude for two hours. Echocardiograph measurements were performed every 20 minutes post-dive. Bubbles were counted and graded using the Germonpré and Eftedal and Brubakk method, respectively. No diver presented with symptoms of DCS following the dive or two hours post-dive at altitude. Despite inter- and intra-diver variability of VGE grade following the dives, the majority (11/20 dives) presented a peak VGE Grade 0, three VGE Grade 1, one VGE Grade 2, four VGE Grade 3, and one VGE Grade 4. Using the cross correction method for a 66-fsw dive at 12,000 feet of altitude resulted in a relatively low decompression stress and no cases of DCS.

Integration of rule-based ‘Expert Systems’ on RPAS capable of Specific Category Operations within the U-space: an original mitigation strategy for operational safety risks

The use of RPAS for civil purposes is spreading across Europe and worldwide; Aviation Authorities are working to layout regulations to assure a safe and secure integration of RPAS with manned aircraft across both controlled and uncontrolled (below 500 Feet of altitude) airspace. Following the identification of a selection of safety risks potentially associated to RPAS Specific Category of operations, an original strategy of risks mitigation focused on rule-based ‘Expert Systems’, has been conceived and it is discussed in this work. The article recalls the main components of rule-based ‘Expert Systems’ that is the knowledge basis and the rules to instruct the ‘Expert system’. Then the work describes the implementation of the rules as statements derived from a safety risk matrix associated to RPAS capable of performing Specific Category operations within the U-space. Finally, the idea of integrating the ‘Expert System’ as a software module within RPAS functional architecture is presented and discussed. Such solution is deemed to be a valuable novelty for future implementations of advanced RPAS autopilots capable of recognizing and solving in flight/on ground operational safety risks in such a way to speed up the integration of RPAS into not segregated airspace and their market development.

System Operation of Regional UTM in Taiwan

The hierarchical unmanned aerial systems (UAS) traffic management (UTM) is proposed for UAS operation in Taiwan. The proposed UTM is constructed using the similar concept of ATM from the transport category aviation system. Based on the airspace being divided by 400 feet of altitude, the RUTM (regional UTM) is managed by the local government and the NUTM (national UTM) by the Civil Aeronautical Administration (CAA). Under construction of the UTM system infrastructure, this trial tests examine the effectiveness of UAV surveillance under 400 feet using automatic dependent surveillance-broadcast (ADS-B)-like on-board units (OBU). The ground transceiver station (GTS) is designed with the adoptable systems. In these implementation tests, five long-range wide area network (LoRa) gateways and one automatic packet reporting system (APRS) I-Gate are deployed to cover the Tainan Metropolitan area. The data rates are set in different systems from 8 to 12 s to prevent from data conflict or congestion. The signal coverage, time delay, data distribution, and data variance in communication are recorded and analyzed for RUTM operation. Data streaming and Internet manipulation are verified with cloud system stability and availability. Simple operational procedures are defined with priority for detect and avoid (DAA) for unmanned aerial vehicles (UAVs). Mobile communication and Zello broadcasts are introduced and applied to establish controller-to-pilot communication (CPC) for DAA. The UAV flight tests are generally beyond visual line-of-sight (BVLOS) near suburban areas with flight distances to 8 km. On the GTS deployment, six test locations examine communication coverage and effectiveness using ADS-B like OBUs. In system verification, the proposed ADS-B like OBU works well in the UTM infrastructure. The system feasibility is proven with support of receiving data analysis and transceiver efficiency. The trial test supports RUTM in Taiwan for UAV operations.

The impact of altitude on screening for critical congenital heart disease.

The objectives were to determine the frequency with which pulse oximetry identifies critical congenital heart defects in asymptomatic full-term and late preterm newborns using the AAP expert panel algorithm in a variety of different hospital settings and to evaluate the impact of altitude on the rate of positive screens. We conducted a prospective clinical study of implementation of a newborn pulse oximetry screening for congenital heart disease in 34 independent hospitals. Infants were eligible for enrollment if their gestational age was 35-44 weeks. Of the 34 sites which enrolled infants into our study, 24 were located at or below 2000 feet; 5 were located between 4700 and 6000 feet and 5 were located above 6000 feet in altitude. We screened 6109 infants; 65 (1.1%) had a positive screen. There were no differences in median gestational age, birth weight, mode of delivery or race/ethnicity for infants with a positive screen compared to infants with a negative screen. Infants with positive screens were more often male and more often born at sites located at high altitudes. The frequency of a positive screen increased from 0.2% for infants born at sites at or less than 2000 feet to 6% for sites located above 6000 feet. We stopped enrollment at the site located at 8163 feet after enrolling 65 infants because 23 (35%) were positive. Screening infants for critical cardiac defects at altitude is complicated by the increased false positive screens.

The New Proof of Ptolemy’s Theorem & Nine Point Circle Theorem

The main purpose of the paper is to present a new proof of the two celebrated theorems: one is “Ptolemy's Theorem” which explains the relation between the sides and diagonals of a cyclic quadrilateral and another is “Nine Point Circle Theorem” which states that in any arbitrary triangle the three midpoints of the sides, the three feet of altitudes, the three midpoints of line segments formed by joining the vertices and Orthocenter, total nine points are concyclic. Our new proof is based on a metric relation of circumcenter.

Altitude Does Not Reduce Concussion Incidence: Letter to the Editor.

Altitude Does Not Reduce Concussion Incidence: Letter to the Editor.

Could the Increased Prevalence of Thrombotic Complications at High Altitude In Polycythemia Vera (PV) Be Contributed by Hypoxia?

AbstractAbstract 1988# Both authors contributed equally.Thrombotic complications are a major cause of morbidity and mortality in polycythemia vera (PV). While the risk of PV thrombotic complications is significantly higher in patients with a previous history of thrombosis or transient ischemic attacks, advanced age (> 60 years), leukocytosis and possibly a high JAK2 V617F allelic burden, other contributing etiologies have not been excluded. It is unclear whether environmental variations including hypoxia could modify thrombosis risk. Chronic hypoxia induces many phenotypic changes, including increased erythropoietin production resulting in secondary erythrocytosis and pulmonary hypertension. Moreover, a congenital disorder of augmented hypoxia sensing at ambient oxygen tension, Chuvash polycythemia, is associated with a marked, yet unexplained, increased rate of thrombotic complications.Salt Lake City, UT is located in a valley at ~5,000 feet of altitude and the surrounding areas from which PV patients are referred ranges from 4,300 to 6,900 feet in altitude. In this area, the average hemoglobin concentration is 0.6–1.3 gm/dL higher than the average US value, indicating a physiological response to this level of hypoxia.To analyze the possible effect of moderate hypoxia on PV thrombotic complications, we retrospectively compared the history of thrombotic complications in PV patients from Salt Lake City and Baltimore, MD, a city with a referral area in which the elevation is <500 feet. A total of 237 PV patients were analyzed in this study; 166 were treated in Baltimore and 71 were treated in Salt Lake City, Their demographics are presented in the Table.Salt Lake City (N = 71)Baltimore (N = 166)PAge (yrs.) mean (SD)67 (13)53 (15)<0.0001Female gender in no. (%)23 (32%)106 (64%)0.0001Disease duration (yrs.) mean (SD)7.8 (7.0)5.6 (5.9)0.021White blood cells (X1000/uL) mean (SD)11.7 (7.4)15.4 (10.7)0.003History of thrombosis no. (%)41 (58%)45 (27%)<0.0001Age at first thrombosis (yrs.) mean (SD)60 (14)55 (19)0.2Patients from Salt Lake City were older than the Baltimore patients, more often male, and had longer disease duration. A history of thrombosis was present in 58% of the Salt Lake City patients compared to 27% of the Baltimore patients (P <0.0001). After adjusting for age, sex and disease duration, Salt Lake City patients had an estimated 3.9-fold increase in the odds of history of thrombosis compared to Baltimore patients (95% confidence interval of 1.9 to 7.8; P = 0.0002).The analysis suggests that hypoxia may modify the PV phenotype. The degree of HIF-1 and HIF-2 augmentation and altered regulation of their target genes, and the potential for increased thrombotic risk due to environmental hypoxia should be evaluated prospectively in PV patients living at different altitudes. Disclosures:No relevant conflicts of interest to declare.

ALTITUDE AND HYPERTENSION

In order to study the prevalence of hypertension and some of the factors relevant to its natural history, cross-sectional surveys were performed during the period 1967 to 1973 in five small Peruvian communities, two located at sea level and three above 13,000 feet of altitude. In total, 4,359 persons were studied at sea level (1,970 males and 2,389 females) and 3,055 at high altitude 2,189 males and 866 females). At high altitude, the age-adjusted prevalence of hypertension (particularly systolic) was definitely low; diastolic hypertension was more frequent in men than in women, and it was commoner than systolic hypertension. The reverse was observed in communities at sea level. Long-term blood pressure changes observed in natives accustomed to high altitudes but living at sea level, as well as in white persons usually living at sea level but residing at high altitude, appear to indicate that environmental forces are more important than genetic predispositions in determing the rarity of hypertension in the highlands. Among the environmental forces, chronic hypoxia seems to play an important causal role.

Effect of high-altitude exposure on myopic laser in situ keratomileusis

Purpose: To study the effect of high-altitude exposure on visual acuity after myopic laser in situ keratomileusis (LASIK). Setting: Aconcagua, Mendoza, Argentina. Methods: In the early postoperative period after uneventful myopic LASIK, 2 physicians prospectively assessed their visual acuity during an ascent of Aconcagua (22841 feet). The distance uncorrected visual acuity (UCVA) and peripheral oxygenation were measured at approximately every 2000 feet of altitude. Results: Both climbers developed a moderate loss of distance UCVA but described normal near and pinhole acuity consistent with a myopic shift. The distance UCVA diminished to 20/100 in the right eye and 20/125 in the left eye of Climber A and to 20/160 and 20/30, respectively, of Climber B. The vision loss worsened with increased altitude, duration of exposure, and decreased peripheral oxygenation. One week after the climb, the manifest refraction demonstrated a small myopic shift in both eyes of Climber A; these subsequently resolved. Conclusions: Two climbers, 8 and 14 weeks after myopic LASIK, experienced vision loss consistent with a temporary myopic shift in the refractive error with ascent to high altitude. Climbers who have LASIK, particularly those in the early postoperative period, should be prepared for visual acuity fluctuations with high-altitude exposure.

Hypoxia and induced mutations in Syrian (golden) hamsters. The origin and perpetuation of a species.

We were able to identify anomalous chromosome patterns-monosomy, trisomy, and polyploidy-in metaphase plates prepared from embryos of Syrian hamsters (Mesocricetus auratus) whose mothers had been exposed to low-pressure hypoxia during the hours after copulation. These females were exposed in a low-pressure chamber for 4 hours at pressures equivalent to 30,000 feet of altitude before (estimated) ovulation to create acid shifts of pH equilibrium in the milieu of newly released eggs during passage of sperm upward, during fertilization itself, and during early cleavage stages. The D group chromosomes were most frequently involved in both monosomy and hyperdiploidy. The easily identifiable X chromosome also appeared to be susceptible to aneuploid formation. Chromosomally abnormal patterns most frequently among sibling embryos conceived by aging mothers exposed to low-pressure hypoxia. The significance of induced mutations is discussed.

Graves triads in the geometry of the triangle

A Graves triad is a cyclic triad of triangles, each circumscribing the next, thus forming a Pappus configuration. In the Euclidean geometry of the triangle the points of contact of the inscribed and escribed circles, the intersections of internal and external angle bisectors with opposite sides, and the feet of altitudes give rise to sixteen Graves triads, in four sets of four each. Each set of four is associated with a rectangular hyperbola through the vertices, orthocentre, in-centre, Gergonne point, and Nagel point, or their external analogues, and having its centre at a Feuerbach point.

Our Cratered Sister Planet

A new radar map of Venus-the most detailed such map ever obtained -shows that surface of cloudcovered planet pocked with craters. Or at least one swatch is-an area 910 miles across, about size of Alaska. region contains a dozen large craters ranging from 21 miles across to one 100 miles across and possibly many smaller craters invisible to radar. craters are all relatively shallow. 100-mile-wide crater only a quarter of a mile deep. This area of Venus appears to be as crater-infested as moon, says Richard M. Goldstein, head of radar mapping team that produced map at Jet Propulsion Laboratory (JPL) in Pasadena. whole area itself basically flat, says Howard C. Rumsey, team member who devised computer techniques for making map. area may vary by no more than about 3,300 feet in altitude. The surprising thing to discover any craters at all, he says. Why are large craters so shallow? That question, says Goldstein, is bound to be important relative to internal and external processes that have gone on [and may still be going on] on Venus. shallow craters could be result of preatmospheric bombardment of planet and then subsequent isostatic readajustment. Extensive internal degassing may have flooded craters with a fill such as lava. Or subsequent erosion on surface could have filled craters with dust. The shallower craters are, says Harold Masursky of U.S. Geological Survey, the more dynamic crust of a planet is. He, along with many others who have been studying craters on earth, moon and most recently Mars, ecstatic about craters on Goldstein's map. Several of us are convinced that surface of Venus will help us understand earth's crust and dynamics that lead to continental drift. He suggests that Venus' crust may be even more mobile than earth's crust, because Venus still hot. But to determine whether craters were made shallow by isostatic readjustment or by lava fill, much-higher-resolution radar maps of Venus' surface would be needed. Masursky suggests that these might be obtainable from a spacecraft placed into orbit around Venus equipped with a radar altimeter and side-looking radar. NASA has been studying such a mission. Certainly seeing through to surface of a cloud-shrouded planet from earth-such as Goldstein's group has done-was no easy task. It took radar. an array of sophisticated computer techniques and signal-processing equipment and a year of painstaking work. just now completed. results are images of surface with a resolution of about six miles-five times better than map of Venus team produced in 1970. JPL scientists used two antennas -the 210-foot dish and 85-foot dish at Goldstone site near Pasadena. 210-foot dish beamed a series of .I.:

Effect of the South Polar Plateau on Plasma and Urine Erythropoietin Levels

The increased level of plasma and urine erythropoietic stimulatory factor in subjects exposed to high altitude is viewed as one of the early manifestations of the individual's acclimatization to the low oxygen environment. The barometric pressure on the South Polar Plateau ranges from 487 to 525 mm Hg which is the equivalent to that, at 11,000 feet of altitude. Plasma erythropoietin activity on the second, third, and fourth days ranged from 0.05 to 0.43 units of erythropoietin and urine erythropoietin values ranged from 0.32 to 73.3 units. These observations indicate that erythropoietin levels of subjects in this environment are similar to those of individuals subjected to low barometric pressure in other less hostile environments.

Systemic blood pressure in white men born at sea level: Changes after long residence at high altitudes

A retrospective survey performed in 100 men born at sea level, residing at 12,398 feet of altitude for 2 to 15 years, has provided a basis for studying the systemic blood pressure changes possibly associated with prolonged residence in a hypoxic environment. Comparison of the blood pressure at the initial and final examinations revealed: (1) decrements of 10 mm. Hg or more for systolic and diastolic pressures in the whole sample in 56 and 46 per cent of the subjects, respectively; (2) significant differences except for diastolic pressure in the subjects with the longest period of residence at high altitude; and (3) in lowlanders, a response of blood pressure to aging at this altitude differing from that at sea level. In general, the final blood pressure closely resembled that observed in healthy natives of the same altitude. Since diet, physical activity on the job, and habits in these subjects were similar to those of their original countries and quite different from those of the Andean population, it seems probable that these findings are causally related to an environmental hypoxic stimulus. Functional or anatomic vascular changes decreasing peripheral vascular resistance to blood flow would be the principal determinant of the observed differences.

Regulation of Erythropoiesis: XXIII. Dissociation between Stem Cell and Erythroid Response to Hypoxia

Abstract The effect of hypoxia on red cell production and stem cells, as measured by CFU, was studied in two strains of mice. One of these strains, the CAF1, has been shown to produce relatively little erythropoietin in response to hypoxia; the other, the CF1, produces substantial amounts of erythropoietin. In the studies reported herein the CAF1 mice had an increase of ∼ 30 per cent in red cell mass after 23 days of exposure to either discontinuous (16 hrs./day) or continuous hypoxia equivalent to 23,000 feet of altitude. The CF1 mouse doubled its red cell mass after similar exposure. The splenic CFU decreased to as low as 17 per cent in the poorly responding CAF1 but remained at or near control levels in the CF1. It is suggested that the dissociation between erythroid response and changes in the CFU reflect a secondary effect of hypoxia not directly related to the erythropoietin-induced increase in red cell production.

Status report on latest development in clear air turbulence.

Jn 1962 and 1963 there was one jet transport accident and several severe incidents which injured passengers and can set! structural damage and/or loss of several thousand feet of altitude because of either connective or clear-air turbulence (CAT). Revised pilot operating instruction for handling turbulence and improved forecasting of CAT has reduced greatly incidents of a drastic nature in 1964 and 1965. The pilot has radar to guide him around storm cores, but he has only the meteorologists' forecasts to tell him where CAT may be encountered. The Air Force, !\avy, ]\ASA, FAA, U. S. Weather Bureau, and the airlines are interested in the development of a good CAT detector. In the Fall of 1964, NASA contracted with Flight Safety Foundation to find out and report on all the activities in the United States and the world in the field of CAT forecasting and detection. This is a service to the governmental departments interested in this Held and to industry. This paper is a status report about new developments in CAT forecasting; it also is a resume of the various proposed principles of CAT detection and the detection devices being developed and laboratory and flight tested.

POLYCYTHEMIA AND RIGHT VENTRICULAR HYPERTROPHY.

Polycythemia was induced in rats by injecting 10 mg CoCl 2 /kg body wt/day intraperitoneally or by placing them in a low pressure chamber at a reduced barometric pressure equivalent to 18,000 feet of altitude for approximately 23 hours/day. After 63 days of treatment a significant hypertrophy of the right ventricular wall was found in both groups of animals. The increase in weight of the right ventricle in the CoCl 2 -injected rats was approximately 45% of that found in rats exposed to chronic hypoxia. Polycythemia was induced in mice by injecting 0.5 ml of packed, whole erythrocytes per day, intraperitoneally, for four consecutive days. A high hematocrit was maintained by additional periodic intraperitoneal injections of erythrocytes. After twenty-two days a significant right ventricular hypertrophy was observed. It is concluded that polycythemia and hypervolemia are important factors in producing right ventricular hypertrophy in rats and mice without airway hypoxia and also may be significant factors in the cardiac hypertrophy induced by high altitude.