The circulatory response to specific ventilatory patterns using a tidal volume ventilator.
The circulatory response to different ventilatory patterns during artificial ventilation was examined in 17 sternotomized piglets. A constant CO2-tension level was maintained in all investigations by reference to analyses of the end-tidal infra-red CO2 fraction and arterial CO2-tension. The greatest variation in mean values for end-tidal CO2-tension was 0.2 kPa. Total compliance and lung compliance were lower at a ventilator volume/pressure quotient of 20 compared to those at 80 ml/kPa, and at f = 30 compared to f = 11 cycles/min. Higher cardiac output, lower pulmonary vascular resistance and systemic vascular resistance were measured at f = 11 (inspiration 20%) than at f = 30 (inspiration 50%). An increase in inspiration time by about 100% at the lower ventilatory frequency (f = 11) resulted in a significant but uncompensated decrease in cardiac output and stroke volume. These results demonstrate the value of a rapid insufflation in order to give longer expiration time per minute for the benefit of the venous return and cardiac output.
D000818:Animals; D002302:Cardiac Output; D006439:Hemodynamics; D008170:Lung Compliance; D008176:Lung Volume Measurements; D010313:Partial Pressure; D011312:Pressure; D012121:Respiration, Artificial; D013318:Stroke Volume; D013552:Swine; D013990:Tidal Volume; D014132:Trachea; D014655:Vascular Resistance; D012122:Ventilators, Mechanical