Validation of XVal-He-8_040 and XVal-He-9_040 Thalmann Algorithm Parameter Sets for Computing Decompression Schedules for Extended Duration 1.3 atm PO2 He-O2 Diving with N2-O2 Decompression

Abstract

The U.S. Navy 1.3 atm PO2 He-O2 Decompression Tables are based on the LEM-he8n25 probabilistic decompression model and all schedules have a near-uniform estimated probability of decompression sickness (PDCS) near 2.3 percent. These decompression tables were developed to support short bottom time, repetitive, multiday diving. To support long, single dives, an algorithm that computed schedules with higher PDCS and consequently faster decompression, and which could be implemented in a dive computer, was desirable. The XVal-He-8_040 and XVal-He-9_040 parameter sets were developed to cause the Thalmann Algorithm to emulate decompression schedules computed with LEM-he8n25 with target PDCS=4 percent. XVal-He-8_040 and XVal-He-9_040 produce nearly identical schedules for the bottom times of interest, and either can be implemented in currently available dive computer hardware (NEDU TR 18-05). Simulated bell lock-out dives were conducted in the NEDU Ocean Simulation Facility to depths (160200 feet of sea water) where bottom times of about two hours could be accomplished with a maximum 8-hour dive time. 44 divers breathing 1.3 atm PO2 He-O2 completed wet, working dives followed by simulated bell lock-in. Decompression according to XVal-He-8_040 Thalmann Algorithm was completed in the dry breathing 1.3 atm PO2 N2-O2 with air breaks. Divers were monitored for VGE with 2-D echocardiography and for symptoms and signs of DCS. 120 man-dives were completed on six schedules. Median peak resting VGE grade (EB scale) was 0 (IQR: 02). One case of Type 1 decompression sickness (knee pain) occurred for a cumulative incidence (95 percent exact binomial confidence limits) of 0.8 percent (0.02 percent , 4.6 percent). Manned-validation of XVal-He-8_040 and XVal-He-9_040 Thalmann Algorithm schedules for long bottom times with decompression in the dry resulted in a low cumulative incidence of DCS.

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Document Details

Document Type
Technical Report
Publication Date
Jul 01, 2019
Accession Number
AD1215272

Entities

People

  • David J. Doolette
  • F. G. Murphy
  • Wayne A. Gerth

Organizations

  • United States Navy Experimental Diving Unit

Tags

DTIC Thesaurus Topics

  • Algorithms
  • Biomedical Research
  • Breathing Gases
  • Data Acquisition
  • Decompression Sickness
  • Divers
  • Diving Operations
  • Gases
  • Health Services
  • Hyperbaric Medicine
  • Measurement
  • Pain
  • Partial Pressure
  • Respiration Disorders
  • Signs And Symptoms
  • Time Domain
  • Two Dimensional

Readers

  • Regression Analysis.
  • Underwater engineering and Marine Technology.