Cardiorespiratory effects of the sitting position in neurosurgery

The cardiorespiratory effects of raising patients from the supine to the sitting position for neurosurgery were investigated. The change caused marked decreases in cardiac index, stroke volume, PaO2 and Qs/Qt, with a significant increase in (PAO2-PaO2) and total peripheral resistance. It is concluded that patients who maintain normotension in the sitting position do not necessarily have an adequate circulatory status.