The inspiratory to end-tidal oxygen difference during exercise
Authors: Bengtsson J.1; Bengtson J.P.2
Source: International Journal of Clinical Monitoring and Computing, Volume 14, Number 4, November 1997 , pp. 217-223(7)
Publisher: Springer
Abstract:
Objective. Fast paramagnetic oxygen analyzers have made it possible to measure inspiratory to end-tidal oxygen concentration difference (P(i-et)O_2) breath-by-breath. It is now frequently displayed on monitors during routine anesthesia. We wanted to study the effects of major changes in metabolism, ventilation and circulation on P(i-et)O_2. Methods. Ten healthy male volunteers were studied under exercise. P(i-et)O_2 was measured with a fast-response paramagnetic differential oxygen sensor. Cardiac output was measured with non-invasive transthoracic electrical bioimpedance. Metabolism was measured with indirect calorimetry and ventilation with a side stream spirometer. After a rest period, the subjects cycled at 30W and 60W, 6 minutes on each work load and were then observed during 10 minutes of rest. Results. P(i-et)O_2 corresponded well to VO_2/VA (the oxygen uptake to alveolar ventilation quotient) correlation showed r = 0.79. P(i-et)O_2 was influenced by changes in cardiac output which occurred primarily at the start and at the end of exercise. Expired minute ventilation (VE) multiplied by P(i-et)O_2 was related to cardiac output with a high intrapersonal correlation. Conclusion. P(i-et)O_2 is a good measure of adequate ventilation in relation to the oxygen consumption level and multiplied by VE it might offer a non-invasive bedside parameter indicating changes in cardiac output.
Keywords: cardiac output; end-tidal oxygen; oxygen consumption; end-tidal carbon dioxide; exercise
Language: English
Document Type: Regular paper
Affiliations: 1: Dep. of Pediatric Anesthesia and Intensive Care, Östra Hospital, Göteborg University, S-416 85 Göteborg, Sweden 2: Dep. of Anesthesia and Intensive Care, Sahlgren University Hospital, Göteborg University, Sweden

Click here for Page Help