18 Clinical Trials for Various Conditions
1) Oxygen Transport in Normobaric versus Hypobaric Hypoxia. 2) The purpose of this study is to examine acute responses in arterial and muscle tissue oxygenation during incremental exercise in normobaric versus hypobaric hypoxia. 3) The participants in this study will consist of 12 recreationally active males and females between the ages of 19 and 45.Recreationally active is defined as participating in moderate to vigorous physical activity for 30 minutes at least 3 days per week.4) Subjects will complete an incremental cycle test to volitional fatigue in three conditions in a randomized counter-balanced order, normobaric normoxia (20.9% O2, 730 mmHg), normobaric hypoxia (14.3% O2, 730 mmHg) and hypobaric hypoxia (20.9% O2, 530mmHg). Two of the three trials will be conducted in an environmental chamber to simulate normobaric normoxia at 350 m (elevation of Omaha, NE) and normobaric hypoxia at 3094 m (elevation of Leadville, CO). The hypobaric hypoxia trial will be conducted in Leadville, Colorado at 3094 m. Trials will be separated by at least two days. Rating of perceived exertion, heart rate, blood oxygenation, respiration rate, muscle tissue oxygenation, and whole body gases will be analyzed during the trials. 5) There is no follow-up as a part of this study.
This study seeks to determine whether a simple, single intervention of Cetirizine / Zyrtec® use can improve exercise performance of active individuals when acutely exposed to altitude. For this project, healthy subjects will perform steady state and progressive work rate exercise, endurance performance time trials, and repeated sprint performance time trials in the laboratory at a simulated altitude of 3000m (9900ft) after dosing with 10 mg of Cetirizine or a placebo in a repeated measures design.
In low oxygen environments, such as altitude, some adults may become ill and suffer from acute mountain sickness. Further, all adults will find that exercising becomes much more difficult when compared with exercise at lower altitudes (e.g. sea-level). The purpose of this investigation is to study the effects of two drugs that may help people adjust to high-altitude quickly, prevent them from becoming ill and improve their exercise performance. The drugs are Methazolamide and Aminophylline.
The investigators expect to find that different intensity and altitude exposure levels will show what kind of intermittent exposure protocol is more beneficial to athletes and healthy individuals that experience acute exposure to altitude during exercise. This may furthermore be related to acute altitude exposure for recreational exercise use as well.
Low oxygen at altitude causes pauses in breathing during sleep, called central sleep apnea. Central sleep apnea causes repeated awakenings and poor sleep. Low oxygen itself and the induced oxidative stress can damage mental function which is likely worsened by poor sleep. Reduced mental function due to low oxygen can pose a serious danger to mountain climbers. However there is also mounting evidence that even in populations of people that live at high altitudes and are considered adapted, low oxygen contributes to reductions in learning and memory. Therefore there is a serious need for treatments which may improve sleep, control of breathing and mental function during low oxygen. Melatonin is a hormone produced in the brain during the night which regulates sleep patterns with strong antioxidant and anti-inflammatory properties. A study previously reported that melatonin taken 90 mins before bed at 4,300 m (14,200 ft) induced sleep earlier, reduced awakenings and improved mental performance the following day. However how melatonin caused these effects was not determined. Therefore this study aims to determine how melatonin effects control of breathing, sleep and mental performance during exposure to low oxygen.
Dyspnea and exercise intolerance are well known to travelers who have experienced time at high elevations, greater than 2500 meters (8200 feet). As individuals ascend to higher elevations, oxygen saturations significantly decrease as the partial pressure of oxygen decreases. Additionally, many individuals develop subclinical cases of high altitude pulmonary edema (HAPE), which may worsen hypoxemia and decrease exercise performance. While dyspnea and exercise intolerance are usually self-limiting and improve with rest, some individuals experience severe symptoms that prevent safe evacuation to lower elevation. Individuals experiencing high altitude dyspnea, subclinical HAPE, or clinical HAPE will see improvements in symptoms and SpO2 when receiving supplemental oxygen, however this requires heavy and unwieldy tanks that make it difficult to carry across irregular terrain. Additionally, given the often-remote conditions where supplemental oxygen is needed, it is often difficult to replenish supplies. Other devices, such as the portable hyperbaric chamber (often referred to as Gamow bag), can temporarily improve dyspnea and oxygen saturation at high and extreme altitudes without the use of oxygen tanks. This device also carries some of the same disadvantages as supplemental oxygen, however, as the bag is also heavy and patients are not ambulatory while using the device. Similar to supplemental oxygen and the portable hyperbaric chamber, there is some evidence that CPAP may improve SpO2 and dyspnea at high and extreme altitudes. CPAP has already demonstrated significant efficacy in reducing symptoms of acute mountain sickness (AMS) when used in the field. At the time these small studies were conducted, CPAP therapy carried similar disadvantages in weight and portability. In recent years, however, CPAP devices have become increasingly lightweight and portable, with recent models weighing less than 1 kilogram (2.2 pounds). These devices are often powered by batteries, which themselves are light and easy to carry, and can be charged in the field using either a generator or foldable solar panels. These newer features of CPAP devices overcome some of the previous disadvantages that have limited its potential uses. CPAP devices can easily be carried across difficult terrain directly to individuals suffering from altitude-related symptoms, to be used as a rescue device until definitive care is available. Its portability not only allows for easy delivery to a patient, but also may allow for a patient to experience enough symptom relief to walk themselves down to lower elevation, greatly improving speed and resource utilization involved in high altitude rescues. In previous studies, CPAP devices have been found to be effective and safe to use in high and extreme altitude locations. While a few pilot studies have assessed CPAP's utility in treating dyspnea and SpO2 at altitude, these studies were done at rest. While one study showed improved symptoms and SpO2 in normobaric and hypobaric hypoxia, the study was limited by its lack of real-world condition, and its authors suggested further study in field and extreme environmental conditions. Additional investigation is needed to determine whether or not CPAP is an effective tool in the field to improve SpO2, dyspnea, and exercise tolerance in individuals traveling at high elevations.
To compare the effects of IV iron versus placebo (saline) injection on arterial oxygen saturation, submaximal exercise responses, and 2-mile treadmill time-trial performance during acute exposure to hypobaric hypoxia (430 mmHg, simulating \~4800m) assessed 1 and 14 days after treatment. Primary Hypothesis 1: IV iron treatment will improve arterial oxygen saturation at rest and during exercise in acute hypobaric hypoxia and this effect will persist for 2 weeks Primary Hypothesis 2) IV iron treatment will improve 2-mile treadmill time trial performance in acute hypobaric hypoxia and this effect will persist for 2 weeks
The aim of this randomized, double-blind study is to determine whether erythropoietin (Procrit) and acetazolamide: 1) mitigates altitude-induced decrements in performance at moderate altitude (3,000 m) and 2) mitigates altitude-induced decrements in performance and reduce acute mountain sickness during prolonged exposure to high altitude (4,300 m; 15 days). Volunteers will complete 5 study phases: Phase 1) sea level baseline testing and a moderate altitude exposure; Phase 2) 4 week study intervention - randomly assigned to receive erythropoietin or placebo); Phase 3) 3 1/2 days of acetazolamide and a moderate altitude exposure; Phase 4) high altitude acclimatization - 15 days at Pikes Peak; and Phase 5) two week deacclimatization. Test battery include VO2peak, 3.2 km treadmill time trial, measures of gas exchange and ventilation during rest and exercise, and blood collection.
This is a randomized, placebo-controlled, crossover study of Trans Sodium Crocetinate (TSC) in healthy volunteers, age 18-40 (inclusive), exercising at altitude. The primary objective is to determine the effect of (TSC) on partial pressure of oxygen (PaO2) and maximal oxygen consumption (VO2 max); the secondary objective is to assess the effect of TSC on oxygen saturation (SpO2).
Low oxygen at altitude causes pauses in breathing during sleep, called central sleep apnea. Central sleep apnea causes repeated awakenings and poor sleep. Low oxygen itself and the induced oxidative stress can damage mental function which is likely worsened by poor sleep. Reduced mental function due to low oxygen can pose a serious danger to mountain climbers. However there is also mounting evidence that even in populations of people that live at high altitudes and are considered adapted, low oxygen contributes to reductions in learning and memory. Therefore there is a serious need for treatments which may improve sleep, control of breathing and mental function during low oxygen.Therefore this study aims to determine how melatonin effects control of breathing, sleep and mental performance during exposure to low oxygen.
The goals of the present study are to evaluate whether the most common, and effective, treatment for acute mountain sickness (AMS), acetazolamide (AZ), has a negative, positive, or no influence on exercise performance, cognitive performance, or manual dexterity in young healthy subjects during simulated altitude exposure. AMS represents a serious challenge to the health and performance of the Warfighter who may need to rapidly deploy to high altitude. However, there have been concerns that AZ might alter or impair endurance exercise performance, and possibly fine motor skills. These would represent major limitations to the use of this drug in a Warfighter who has a specific timeframe in which to accomplish mission tasks. In the present project, we will use exposure to simulated altitude in the USARIEM hypobaric chamber to quantify the impact, if any, of AZ on endurance exercise performance following rapid ascent to 3500 meters (m) in unacclimatized lowlander volunteers. The study will be conducted using a randomized, single-blind, placebo-controlled crossover study design. Ten male and female volunteers will complete one orientation day, one VO2peak day, three days of familiarization testing at sea level (SL), then two rounds of experimental testing. Each round of experimental testing consists of six days including four days to establish baseline euhydration, followed by a 30 hour (hr) exposure to 3500 m. Volunteers will have a two week break between experimental testing rounds for washout of any effects of altitude acclimation. During one experimental round, volunteers will take two doses of AZ each day (Phase 1: 250 mg/dose,500 mg/day, Phase 2: 125 mg/dose, 250 mg/day) starting 48 hr prior to their altitude exposure and continuing for the 30 hr stay at high altitude. During the other experimental condition, volunteers will be given a placebo at the same time points as the doses of AZ. Prior to altitude exposure, AMS will be evaluated and volunteers will then ascend to a simulated altitude of 3500 m, where they will remain for 30 hr. Volunteers will rest at altitude for an hr, after which they will complete an AMS questionnaire, resting ventilation measurements, provide a blood sample and complete cognitive and finger dexterity testing. Subjects will then perform 15 minutes (min) of steady state (SS) treadmill exercise at 40-45% of SL VO2peak and a 2 mile treadmill time trial (TT). Volunteers will stay overnight in the hypobaric chamber with research staff supervision. The following morning, metabolic and blood measurements will again be completed, after which volunteers will perform the exercise testing for a second time. Cognitive and finger dexterity testing will be performed before volunteers return to sea level (i.e., "descend" from the simulated altitude). The results of the proposed study will, for the first time, provide quantitative evidence regarding whether AZ treatment impairs endurance exercise performance in the context of a Warfighter-relevant endurance exercise task.
Ibuprofen is often taken by travelers to high altitude to treat the symptoms of acute mountain sickness such as headache and malaise. However, the blunting of inflammation by ibuprofen may slow the process of acclimatization to altitude, which relies on mediators of inflammation for adjustments in breathing. The study randomizes healthy subjects to receive ibuprofen or placebo and then ascend to altitude (12,500 feet). Blood cytokines and non-invasive measurements of blood and tissue oxygen levels will be made for 48 hours at altitude. The hypothesis being tested is that subjects receiving ibuprofen will have lower blood and tissue oxygen levels after 48 hours at altitude than will placebo subjects.
The purpose of this study is to look at how a reduction in oxygen levels (hypoxia) influences insulin sensitivity and carbohydrate metabolism. It is expected that 10 nights of exposure to moderate hypoxia (\~ 15% O2, similar to conditions at an altitude of \~7500 feet) will improve glucose metabolism.
The proposed study is a prospective, randomized, double-blind, placebo-controlled clinical trial evaluating ibuprofen and placebo for the prevention of neurological forms of altitude illness \[including high altitude headache (HAH), acute mountain sickness (AMS), high altitude cerebral edema (HACE), and an emerging concept of High Altitude Anxiety\]. The study will take place in the spring and summer of 2012 at the Marine Corps Mountain Warfare Training Center in the Eastern Sierras near Bridgeport, California. US Marines from near sea level will participate in battalion-level training exercises at between 8,500-11,500 Feet, where some altitude illness is expected. Concurrent measures used to determine objective markers of altitude illness, such that validated clinical scales, rapid cognitive screening tests, will inform us of symptoms of altitude illness.
The main purpose of this study is to determine if a drug (acetyl-cysteine or ACCY) can increase the amount of oxygen in your body at a high altitude of 11,500 feet. ACCY is approved by the Food and Drug Administration (FDA) as a treatment or antidote for Tylenol overdoses. Other forms of ACCY are also sold over-the-counter as nutritional supplements. In this study, the FDA-approved form of ACCY will be used "off-label" (meaning in a way not approved by the FDA). This study is being conducted by researchers from the United States Army Research Institute of Environmental Medicine (USARIEM). The study will take place in the Altitude Chamber located in the basement of USARIEM. A total of approximately 30 volunteers (men and women, military and civilians) will take part in the study. They can expect to be in the study for a minimum of a few hours each day for two weeks. The investigators hypothesize that ACCY will improve ventilation and oxygenation while at altitude.
Hypobaric hypoxia (decreased oxygen supply to body tissues due to low atmospheric pressure) caused by exposure to high altitude disrupts sleep. Sleep deprivation is associated with degraded post-sleep performance of neurobehavioral tasks. The lowest altitude at which sleep and/or post-sleep performance are affected is not known. The study hypothesis is that sleep and/or post-sleep performance of neurobehavioral tasks will occur due to hypobaric hypoxia at altitudes of 8,000 or less.
This study is to determine whether bosentan will alter exercise capacity after rapid ascent to high altitude. We hypothesize that bosentan administration will improve arterial oxygenation and exercise capacity.
The current protocol is composed of two studies. The first study is designed to carefully evaluate the safety of high-dose salmeterol/fluticasone (Advair HFA) versus placebo (hydrofluoroalkane, HFA) administration over 7 days, as well as the efficacy of the study drug to increase exercise performance, in healthy individuals exercising under hypoxic, simulated high-altitude conditions (Phase 1/2a study). The second study will examine sensitive measures of cardiopulmonary function using invasive cardiopulmonary testing, in both HAPE-sensitive and HAPE-resistant individuals, to assess the potential efficacy of salmeterol/fluticasone to prevent pulmonary edema and to enhance exercise capacity (Phase 2a) in these individuals.