On-line computer estimation of carbon dioxide response curves

Duane L. Sherrill, George D. Swanson

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Anesthesiologists are concerned with the effect of various anesthetics on a patient's central nervous ventilatory control. The most widely accepted method of determining the effect of a drug is to compare carbon dioxide response curves (Δ {Mathematical expression}e/ΔP etCO2, where {Mathematical expression}e = minute ventilation [in L/min] and PetCO2 = end-tidal carbon dioxide [in mm Hg]) measured before and after administration of the drug. Additional information concerning neuromechanical control can be obtained by also including a measure of the airway occlusion pressure (generally measured 100 ms after occlusion, i.e., P100). To facilitate these measurements we have developed a portable, computer-controlled data acquisition system. It includes an Apple II+ computer and measures {Mathematical expression}e, PetCO2, and P100. Each subject rebreathes exhaled carbon dioxide through a two-way breathing valve attached to a 9-liter reservoir, which is initially filled with 5% carbon dioxide and balance oxygen. Exhaled carbon dioxide concentrations are measured with an infrared medical gas analyzer on samples taken through a catheter connected at the mouthpiece. The exhaled flow is measured with a pneumotachograph in conjunction with a differential pressure transducer, and P100 is determined with a Validyne MP45 pressure transducer.

Original languageEnglish (US)
Pages (from-to)198-202
Number of pages5
JournalJournal of Clinical Monitoring
Issue number3
StatePublished - Jul 1986
Externally publishedYes


  • Carbon dioxide
  • Equipment
  • Measurement techniques
  • Statistics
  • Ventilation
  • carbon dioxide response curves
  • central nervous ventilatory control
  • computer data acquisition
  • hypercapnic response
  • linear regression
  • ventilatory response

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine


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