Research Article29th Annual New Horizons Symposium: Back to Basics—Respiratory Physiology in Critically Ill Patients

Cardiorespiratory Interactions: The Relationship Between Mechanical Ventilation and Hemodynamics

Ira M Cheifetz
Respiratory Care December 2014, 59 (12) 1937-1945; DOI: https://doi.org/10.4187/respcare.03486

Article Figures & Data

Figures

  • Fig. 1.
    Fig. 1.

    Primary determinants of oxygen delivery. Hb = hemoglobin; SaO2 = arterial oxygen saturation.

  • Fig. 2.
    Fig. 2.

    Effects of mean intrathoracic pressure on systemic vascular return. Systemic venous return to the right atrium is passive, with blood flow occurring as a result of a pressure gradient between the superior/inferior vena cava and right atrium. PSV = systemic venous pressure; RAP = right atrial pressure; PPV = positive-pressure ventilation.

  • Fig. 3.
    Fig. 3.

    Effects of preload augmentation on systemic vascular return. Intravascular fluid administration shifts the systemic venous return line upward and rightward. Thus, for the same right atrial pressure (mean intrathoracic pressure), systemic venous return is augmented. PSV = systemic venous pressure.

  • Fig. 4.
    Fig. 4.

    Effects of intrathoracic pressure on left ventricular (LV) afterload. An augmentation of mean intrathoracic pressure will reduce left ventricular afterload. PPV = positive-pressure ventilation; AO = aorta.

  • Fig. 5.
    Fig. 5.

    Effects of mean lung volume on pulmonary vascular resistance (PVR). Right ventricular afterload is affected by mean lung volume. A: Component of PVR related to the larger pulmonary vessels. B: Component of PVR related to the smaller pulmonary vessels. C: Total PVR.

  • Fig. 6.
    Fig. 6.

    Effects of oxygen delivery on tissue oxygenation. The dotted vertical line represents the anaerobic threshold.

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