Clinical Aspects of Capnography
Capnography permits recognition of CO2 concentration changes in the patient’s airway during the respiratory cycle. The capnogram represents total CO2 eliminated by the lungs, given that no gas exchange occurs in the airways. Expired gas contains CO2 from three sequential compartments: phase I contains gas from apparatus and anatomic dead space, phase II represents increasing CO2 concentration resulting from progressive emptying of alveoli, and phase III represents essentially alveolar gas. The highest point is the end-tidal PCO2 [1–4].
KeywordsMechanical Ventilation Pulse Oximetry Spontaneous Breathing Alveolar Ventilation Intermittent Mandatory Ventilation
- 3.Hess D (1990) Capnometry and capnography: technical aspects, physiologic aspects, and clinical applications. Respir Care 35:557–576Google Scholar
- 14.Smith RA, Novak RA, Venus B (1989) End-tidal CO2 monitoring utility during weaning from mechanical ventilation. Respir Care 34:972–975Google Scholar
- 15.Rehder K, Marsch HM (1986) Respiratory mechanics during anesthesia and mechanical ventilation. In: Fishman AP (ed) Handbook of Physiology. Section 3: Respiration, vol 3. American Physiological Soc., Bethesda, pp 737–752Google Scholar
- 16.Hess D, Schlottag A, Levin B et al (1991) An evaluation of the usefulness of end-tidal PCO2 to aid weaning from mechanical ventilation following cardiac surgery. Respir Care 36:837–843Google Scholar
- 22.Nunn JF (1987) Applied respiratory physiology. 3rd ed. Butterworths, LondonGoogle Scholar