Influence of the Ventilatory Cycle on Cardiac Output Determination during Mechanical Ventilation

Abstract

The effects of different conditions during mechanical ventilation on the accuracy of thoracic electrical bioimpedance compared to the standard thermodilution method were evaluated in 12 adult men and women undergoing neurosurgical removal of intracranial tumors or aneurysms. Measurements were made (1) at fixed points of the ventilatory cycle and (2) spread over the entire ventilatory cycle with a low respiratory rate and a high tidal volume and with a high respiratory rate and low tidal volume. There was no significant difference in cardiac output measurements for all conditions (total(TD) = 3.72 liters/min and total(TEB) = 3.69 liters/min with a mean difference of 0.85% for all conditions). In conclusion, thoracic electrical bioimpedance is an appropriate method for measuring cardiac output during different conditions of mechanical ventilation.