Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content ++Figure 43-1. Normal CapnogramGraphic Jump LocationView Full Size||Download Slide (.ppt)(I) Anatomic dead space.(II) Transition from anatomic dead space to alveolar plateau.(III) Alveolar plateau (typically slight upward slope).Reproduced from Longnecker DE, Brown DL, Newman MF, Zapol WM. Anesthesiology. Figure 31-7. Available at: http://www.accessanesthesiology.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved. ++ Healthy lungs: 2–3 mm Hg awake, 5–8 mm Hg anesthetizedCOPD: up to 10 mm Hg awake, 15–20 mm Hg anesthetizedFurther increased by heat/moisture exchangerFurther increased by V/Q mismatch: PE, hypovolemia, lateral position ++Table Graphic Jump Location | Download (.pdf) | PrintCauses of Acute Changes in CapnogramExponential decreaseIncreased dead space (suspect PE or arrest)Sudden drop to zeroLikely circuit disconnectGradual decrease but not to zeroLeakage or partial obstruction of airwayAir embolism, PEDrop in CO: hypovolemia, IVC cross-clampingDecrease in metabolic rate: hypothermia, deep anesthesiaGradual increaseProlapse of expiratory valve or decreased minute ventilationSudden increaseRelease of tourniquet, aortic unclamping, MH++Figure 43-2. Changes in Capnogram in Different Disease StatesGraphic Jump LocationView Full Size||Download Slide (.ppt)(A) A normal capnograph demonstrating the three phases of expiration: phase I—dead space; phase II—mixture of dead space and alveolar gas; phase III—alveolar gas plateau. (B) Capnograph of a patient with severe chronic obstructive pulmonary disease. No plateau is reached before the next inspiration. The gradient between end-tidal CO2 and arterial CO2 is increased. (C) Depression during phase III indicates spontaneous respiratory effort. (D) Failure of the inspired CO2 to return to zero may represent an incompetent expiratory valve or exhausted CO2 absorbent. (E) The persistence of exhaled gas during part of the inspiratory cycle signals the presence of an incompetent inspiratory valve. Reproduced from Morgan GE, Mikhail MS, Murray MJ. Clinical Anesthesiology. 4th ed. Figure 6-25. Available at: http://www.accessmedicine.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved. ++1. Swedlow DB. Capnometry and capnography: the anesthesia disaster early warning system. Semin Anesth. 1986;3:194–205.++2. West JB. Respiratory Physiology: The Essentials. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2000. ++3. Berengo A, Cutillo A. Single-breath analysis of carbon dioxide concentration records. J Appl Physiol. 1961;16:522–530. Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth