A Method to Determine Accuracy in End-Tidal Carbon Dioxide Monitoring

Abstract

An injection system was developed to determine the accuracy of end- tidal monitoring of carbon dioxide in a hyperbaric chamber. Sample tube diameter, flow rates, placement of reducing valves to control flow, and water traps were studied with sample tubes (34 m long) from 1,000 to 150 feet of sea water (FSW). A sensitive indicator of sample tube mixing in response time, defined as time to reach 90% of full scale deflection of a known calibration gas injection. From 1,000 to 380 FSW, ideal sample tube was Lee (internal diameter = 0.0.32 in) and from 190 to 150 FSW, Nylaflow (internal diameter = 0.078 in). Sampling rate of 2,500 ml/min, controlled at depth, gave adequate response times of 240 to 320 msec for injections from 1,000 to 150 FSW. Controlling the flow at the surface, using water traps (test tubes) and sample flows less than 2,500 ml/ min prolonged the response time to unacceptable levels. This technique predetermines appropriate sample tube diameter and flow and eliminated sources of mixing to insure accurate end-tidal CO2 measurements. (JES)

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Document Details

Document Type
Technical Report
Publication Date
May 01, 1990
Accession Number
ADA224079

Entities

People

  • John A. Sterba

Organizations

  • United States Navy Experimental Diving Unit

Tags

Communities of Interest

  • Biomedical

DTIC Thesaurus Topics

  • Accuracy
  • Availability
  • Calibration
  • Carbon Dioxide
  • Classification
  • Data Analysis
  • Deflection
  • Flow Rate
  • Hyperbaric Chambers
  • Indicators
  • Mass Spectrometers
  • Measurement
  • Monitoring
  • Partial Pressure
  • Sea Water
  • Security
  • Spectrometers

Readers

  • Analytical Chemistry
  • Mathematics or Statistics
  • Plasma Physics.