Fig. 4

The impacts of positive end-expiratory pressure on common carotid arterial blood flow (Series IV, n = 6). Data were presented as mean and standard deviation. RM-ANOVA was used. The corresponding changes of mean arterial pressure were presented in grey lines (showing means only), solid line: pre-exsanguination, dash line: post-exsanguination. A Common carotid arterial blood flow decreased significantly when PEEP was increased (p < 0.001 for both conditions), and the magnitude was significantly greater in the post-exsanguination (i.e., hypovolemic) condition than in the pre-exsanguination (i.e., normovolemic) condition (p < 0.001). B CO significantly decreased with PEEP increment (p < 0.001 for both conditions), there was a significantly greater decrease in CO in the post-exsanguination condition than in the pre-exsanguination condition (p < 0.001). PEEP positive end-expiratory pressure, CO cardiac output