Using ventilator and cardiovascular graphics in the patient who is hemodynamically unstable.
The interaction of a mechanical ventilator and the human cardiovascular system is complex. One of the most important effects of positive-pressure ventilation (PPV) is that it can decrease venous return. PPV also alters right- and left-ventricular ejection. Increased lung volume increases right-ventricular size by increasing pulmonary vascular resistance, causing intraventricular cardiac-septum shift, and decreasing left-ventricular filling. Increased intrathoracic pressure reduces afterload on the LV and increases ejection of blood from the LV. Understanding and managing these complex and often opposing interactions in critically ill patients is facilitated by analysis of hemodynamic and ventilator waveforms at the bedside. The relationship of PPV to changes in the arterial pressure waveform gives important information regarding appropriate fluid and vasopressor treatment. This article focuses on effects of respiratory pressures on hemodynamics and considers how cardiac pressures can be transmitted to the airway and cause ventilator malfunction.
Murphy
Bryant A
BA
Department of Anesthesiology, University of Virginia Helth Science Center, PO Box 800710, Charlottesville, VA 22908-0170, USA. cgd8v@virginia.edu
Durbin
Charles G
CG
D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000209:etiology; D003196:Computer Graphics; D003626:Data Display; D006439:Hemodynamics; D006801:Humans; D008170:Lung Compliance; D011175:Positive-Pressure Respiration / Q000009:adverse effects / Q000379:methods; D012120:Respiration Disorders / Q000503:physiopathology* / Q000628:therapy*; D012121:Respiration, Artificial / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D013318:Stroke Volume; D012122:Ventilators, Mechanical; D016276:Ventricular Function