Cardiovascular effects of mechanical ventilation.
OBJECTIVE
To review the cardiovascular effects of spontaneous breathing and mechanical ventilation in healthy and pathological states.


METHODS
A review of articles published in peer-reviewed journals from 1966 to 1998 and identified through a MEDLINE search on cardiopulmonary interaction.


RESULTS
Respiration has a hydraulic influence upon cardiovascular function. Pulmonary and cardiac pathology alter this interaction. Spontaneous inspiration increases right ventricular (RV) preload and left ventricular (LV) afterload. Mechanical ventilation with positive pressure (MV) reduces LV preload and afterload. The influence of MV upon the cardiovascular system (CVS), particularly in critically ill patients, depends upon the mode of ventilation and the pre-existing cardiac and respiratory status. The influence of these factors is reviewed. Consideration of these parameters will enable the clinician to predict the likely effect of MV and develop strategies to minimise adverse events.


CONCLUSIONS
Mechanical ventilation has an adverse effect upon the CVS in healthy subjects and in patients with pulmonary pathology, particularly in the presence of preload-dependent LV dysfunction or afterload-induced RV dysfunction. Mechanical ventilation may benefit cardiac function in patients with respiratory failure and afterload-dependent or exercise-induced LV dysfunction.
Duke
G J
GJ
Intensive Care Department, The Northern Hospital, Epping, Victoria. gduke@tnh.vic.gov.au