Abstract 11936: The Value of Pulse Wave Timing Properties in the Detection of Circulatory Shock
The value of pulse wave timing properties in detection of circulatory shock has recently been shown using the relative ventilatory variation in the pre-ejection period (ΔPEP). Here we aimed to improve the use of pulse wave timing properties in shock by testing the hypothesis that the relative ventilatory variation in the isovolumic contraction period determined by arterial pulse wave analysis (ΔAIC) is a more reliable indicator of blood loss than ΔPEP, as ΔPEP is influenced by pulse wave travel time and ventricular electro-mechanical delay. For this purpose, we studied the responses of ΔAIC and ΔPEP to a graded hemorrhage protocol, and compared these to the response of stroke volume (SV) and the clinically used pulse pressure variation (ΔPP). ΔAIC and ΔPEP were determined from both the aortic and the carotid pulse wave (subscript indices Ao and Ca respectively). A graded hemorrhage protocol (blood withdrawal up to 20ml/kg) was performed in 7 anesthetized swine. Both ΔPEPAo and ΔAICAo correlated well with SV (r=-0.51, p<0.01 and r=-0.64, p<0.001, respectively) and ΔPP (r=0.91, p<0.001 and r=0.87, p<0.001, respectively). Similarly, ΔPEPCa and ΔAICCa correlated well with SV (r=-0.49, p=0.01 and r=-0.63, p<0.001 respectively) and ΔPP (r=0.85, p<0.001 and r=0.78, p<0.001, respectively). The relative ventilatory variation in electro-mechanical delay did not significantly contribute to the increase in ΔPEPAo following hemorrhage, indicated by the lower magnitude of ΔPEPAo as compared to that of ΔAICAo (see figure). As expected, pulse travel time decreased ΔPEP, indicated by a significantly lower ΔPEPCa as compared to ΔPEPAo (p<0.001). In contrast, ΔAICAo was not significantly different from ΔAICCa. These results support the value of pulse wave timing properties in the detection of shock, and show the superiority of ΔAIC over ΔPEP as an indicator of a decreased circulating blood volume since it is independent of the measurement site.
- © 2011 by American Heart Association, Inc.