Decompression Tables for Diving at Altitude

checkorphan
Learn more about:
Acute mountain sickness
Related Clinical Trial
Effect of Acetazolamide on Sleep Disordered Breathing in Lowlanders Older Than 40 Years at Altitude Effects of Melatonin on Sleep, Ventilatory Control and Cognition at Altitude. Effect of Acetazolamide on Lung Water Content by Ultrasound in Lowlanders Older Than 40 Years at Altitude Effect of Acetazolamide on Right Heart Function During Exercise in Lowlanders Older Than 40 Years at Altitude Effect of Acetazolamide on Visuo-motor Learning in Lowlanders Older Than 40 Years at Altitude Effect of Acetazolamide on Maximal Exercise Performance in Lowlanders Older Than 40 Years at Altitude Physiological Adaptations to Simulated Intermittent Altitude on Human Health and Performance Iron Status and Cardiopulmonary Physiology Effect of Acetazolamide on Right Heart Function at Rest in Lowlanders Older Than 40 Years at Altitude. Effect of Acetazolamide on Postural Control in Lowlanders Older Than 40 Years at Altitude Monitoring of the Cerebral Tissue Oxygenation and Perfusion in the Adapting Climber During Sleep in High Altitude The Psychophysiological Effect of Simulated and Terrestrial Altitude Relationship Between Succinate Dehydrogenase Mutations and High-Altitude Illness Cardio-respiratory Responses During Hypoxic Exercise in Individuals Born Prematurely Gut-microbiota Targeted Nutritional Intervention for Gut Barrier Integrity at High Altitude AZ, MZ, and the Pulmonary System Response to Hypoxia Study of the Effects of Iron Levels on the Lungs at High Altitude Effects of Aircraft Cabin Altitude on Passenger Comfort and Discomfort Three New Ideas to Protect Special Forces From the Stress of High Altitude Breathing Training to Improve Human Performance at High Altitude Oxidative Stress in Hypobaric Hypoxia Safety Evaluation of Aminophylline and Methazolamide Decompression Tables for Diving at Altitude Chronic Mountain Sickness, Systemic Vascular Function Evaluation of the Prevention and Treatment Effects of Chinese Medicine on High Altitude Illness Inhaled Budesonide for Altitude Illness Prevention Sickness Evaluation at Altitude With Acetazolamide at Relative Doses Prevention of Altitude Illness With Non-steroidal Anti-inflammatory Study (PAINS) Spectroscopic and Diffusion Weighted Analysis of the Effects of Dexamethasone on High Altitude Cerebral Oedema (HACE) Drug Combination on Exercise Performance at High Altitude Acclimatization Mechanisms During Ascent to 7500m Prevention of Acute Mountain Sickness by Intermittent Hypoxia Sickness Evaluation at Altitude With Acetazolamide at Relative Dosages Study Looking at End Expiratory Pressure for Altitude Illness Decrease (SLEEP-AID) Can Rhodiola Crenulata Intake Improve Oxygen Saturation and Decrease the Incidence of Acute Mountain Sickness Comparison of Metoclopramide and Ibuprofen for the Treatment of Acute Mountain Sickness A Trial of Acetazolamide Versus Placebo in Preventing Mountain Sickness During Rapid Ascent Training in Hypoxia to Prevent Acute Mountain Sickness Study of Compound Danshen Dripping Pills to Treat Acute Mountain Sickness Altitude Sickness Prevention With Ibuprofen Relative to Acetazolamide and Treatment Efficacy Controlled Hyperventilation as Prophylaxis for Acute Mountain Sickness Inhaled Budesonide and Acute Mountain Sickness Altitude Sickness Prevention and Efficacy of Comparative Treatments Alternative Treatments in Acute Mountain Sickness Effect of Acetazolamide on Acute Mountain Sickness in Lowlanders Older Than 40 Years Safety and Efficacy of T89 in Prevention and Treatment of Adults With Acute Mountain Sickness (AMS)

Brief Title

Decompression Tables for Diving at Altitude

Official Title

Development of Decompression Tables for Diving at Altitude

Brief Summary

      The aims of this proposal are to test current USN procedures for adjusting decompression
      procedures during air diving at 8,000 and 10,000 ft altitude and to provide a decompression
      algorithm for no-stop dives to 100 feet of sea water (fsw) at 10,000 and 12,000 ft altitude
      using enriched O2 (PO2=1.3 ATM). Additionally, the experiments will determine whether a
      period of hyperbaric hyperoxia, such as would be experienced during a dive at altitude,
      reverses altitude acclimatization, resulting in a return of acute mountain sickness (AMS)
      symptoms.

Detailed Description

      Three different types of experiments will be performed:

      (A). Testing of Cross corrections breathing air at 8,000 (0.743 ATA) and 10,000 ft (0.688
      ATA). Subjects will be decompressed in a hypobaric chamber to one of the altitudes above. A
      no-stop dive to 60 fsw will be tested at each altitude (2.82 ATA at sea level, 2.56 ATA at
      8,000 ft, 2.51 ATA at 10,000 ft). Using the Cross corrections, the virtual depth for both
      altitudes is 90 fsw, for which the no-stop time is 30 minutes. During the dive the subject
      will be immersed/submersed at rest/mild exercise in 28°C water. Ascent rate will be 30
      fsw/min. Upon surfacing the diver will be monitored for 12 hours for symptoms of
      decompression sickness and transthoracic echocardiography (rest and leg/arm motion) to
      examine for venous gas embolism (VGE) at 5, 15, 30, 60 and 120 minutes after surfacing. After
      that, measurements will be continued until no bubbles are detected.

      (B). Testing of a no-stop dive to 100 fsw at 10,000 ft and 12,000 ft breathing 35% O2. For
      this series of experiments all subjects will remain at altitude for 48 hours before diving,
      in order to allow for resolution of AMS symptoms. Appropriate depth-time profiles have been
      assessed by calculating the equivalent sea level air depth for each of these dives (PN2
      values 2.42 and 2.36 ATM, respectively). These yield equivalent air depths of 68 and 66 fsw,
      respectively. Cross corrected virtual depths would therefore be 99 and 104 fsw, yielding
      no-stop times of 25 and 20 minutes, respectively. The Cross correction method will be used in
      this instance because, although largely untested, it is presently in use by the Navy. As with
      the air dives described above, the more provocative dives (12,000 ft) will be completed
      before the ones at 10,000 ft, which will increase the confidence for the bottom time used at
      the lower altitude.

      (C). Testing to determine whether a high PO2 dive would reverse altitude acclimatization and
      re-establish susceptibility to AMS. Subjects will ascend in the chamber to 15,000 ft in a
      graded fashion over 12 hours (15,000 ft has been chosen due to extensive Duke experience with
      this altitude). Then, after 48 hours they will simulate a hyperoxic dive by breathing 100% O2
      for 120 minutes at 1.3 ATA. This will simulate, for example, a 2 hour dive at 12,000 ft to 65
      fsw breathing 50% O2. The diver will then return to 15,000 ft and remain at that altitude for
      24 hours to allow for AMS symptoms to recur (if indeed they do). Lake Louise AMS scores will
      be collected every 8 hours. AMS symptoms will be treated with acetaminophen, NSAIDs and
      anti-emetics as needed. Subjects will be assessed clinically every 12 hours for high altitude
      pulmonary edema (HAPE) and high altitude cerebral edema (HACE). Occurrence of either HAPE or
      HACE will require that the subject be returned immediately to 1 ATA and treated
      appropriately.

Study Type

Interventional

Primary Outcome

Decompression Sickness

Secondary Outcome

 Venous Gas Emboli

Condition

Decompression Sickness

Intervention

Pressure

Study Arms / Comparison Groups

 Altitude Dive Altitude profile
Description:  Subjects are exposed to Pressure profiles (Altitude followed by a Dive with a return to Altitude) and Breathing Gases during dive exposures.

Publications

* Includes publications given by the data provider as well as publications identified by National Clinical Trials Identifier (NCT ID) in Medline.

Recruitment Information

Recruitment Status

Other

Estimated Enrollment

72

Start Date

February 13, 2018

Completion Date

October 2020

Primary Completion Date

October 2020

Eligibility Criteria

        Inclusion Criteria:

        -

        Exclusion Criteria:

          -  smoking, cardiorespiratory disease (including hypertension, airways obstruction),
             seizure disorder, pregnancy, history of middle ear or sinus disease or high altitude
             cerebral or pulmonary edema (HACE, HAPE), inability to perform middle ear
             autoinflation, anemia, sickle cell disease and sickle cell trait. Individuals with
             VO2peak <35 mL.kg-1.min-1 (males) and <30 mL.kg-1.min-1 (females)

Gender

All

Ages

18 Years - 40 Years

Accepts Healthy Volunteers

Accepts Healthy Volunteers

Contacts

Richard Moon, MD, ,

Location Countries

United States

Location Countries

United States

Administrative Informations

NCT ID

NCT03390335

Organization ID

Pro00087803

Responsible Party

Sponsor

Study Sponsor

Duke University

Collaborators

 United States Department of Defense

Study Sponsor

Richard Moon, MD, Principal Investigator, Duke Universtiy Health System

Verification Date

August 2020