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Bhavani Shankar Kodali MD

Analysis of CO2 waveforms: 4

Clinical Aspects

Bhavani Shankar Kodali MD

Analysis of CO2 waveforms:  

Height of the plateau:
Increases in metabolism raise the height of the plateau whereas decreases in metabolism, cardiac output and effective circulating blood volume reduce the height.1-8 The height of the plateau is also dependent on ventilation. Hyperventilation decreases it whereas hypoventilation can result in a gradual increase in the height of the plateau.

 Hypermetabolic states increase the height of the capnograms


 Decreases in cardiac output decreases the height of capnograms


 Effective circulating blood volume can reduce the height of capnograms


 Hypoventilation  (Gradual elevation of the height of the capnogram, base line remaining at zero)


 Hyperventilation (Gradual decrease in the height of the capnogram, base line remaining at zero)


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2.    Askrog V.  Changes in  (a-A)CO2 difference and pulmonary artery pressure in anesthetized man. J Appl Physiol 1966;;21:1299-1305.

3    Shibutani K, Muraoka M, Shirasaki S, Kabul K, Sanchala VT, Gupte P.  Do changes in end-tidal PCO2 quantitatively reflect changes in cardiac output? Anesth Analg 1994;79:829-33.

4.    Maslow A, Stearns G, Bert A, Feng W, Price D, Schwartz C, Mackinnon S, Rotenberg F, Hopkins R, Cooper G, Singh A, Loring SH. Monitoring end-tidal carbon dioxide during weaning from cardiopulmonary bypass in patients without significant lung disease. Anesth Analg 2001;92:306-13.

5.    Weil MH, Bisera J, Trevino RP, Rackow EC.  Cardiac output and end-tidal carbon dioxide. Crit Care Med 1985;13:907-9.

6.    Ornato JP, Garnett AR, Glauser FL.  Relationship between cardiac output and the end-tidal carbon dioxide tension.  Ann Emerg Med 1990;19:1104-6.

7.    Jin X, Weil MH, Povoas H, Pernat A, Xie J, Bisera J.  End-tidal carbon dioxide as a noninvasive indicator of cardiac index during circulatory shock. Crit care Med 2000;28:2415-9.

8.    Isserles SA, Breen PH.  Can changes in end-tidal PCO2 measure changes in cardiac output? Anesth Analg 1991;73:808-14.

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