A square-pulse flow method for measuring characteristics of the arterial bed

Abstract

A device was designed to provide a "square" pulse of blood flow into the arterial system. Pulses were injected into the carotid artery of the rabbit during transient cardiac arrest. Analysis of pressure response curves generated by the flow provides information as to the state of the arterial tree. With certain assumptions it is possible to estimate from these curves lumped values of peripheral resistance, critical closing pressure, and arterial compliance. In a series of 12 rabbits the mean value of peripheral resistance was found to be 0.21 +/- 0.7 mmHg-ml-1-min and critical closing pressure was estimated to be 23.6 +/- 3.8 mmHg. This method gives two possible values for arterial compliance 0.036 +/- 0.010 and 0.055 +/- 0.010 ml-mm-1 based, respectively, on the rise and decay curves of the pressure response. The theory and limitations of the method are discussed. The use of the method is illustrated in following the response to increased PCO2 and hemorrhage.

The modified arterial reservoir: An update with consideration of asymptotic pressure (P∞) and zero-flow pressure (Pzf)

“…A total of 1255 unique publications were identified after removal of duplicates; 1235 were excluded during screening. The remaining 20 studies 48–51,54–69 with P zf data were included in a meta-analysis (Figure 3); these included data from dog, rat, pig and human; eight of these articles also provided data on MCFP from the same studies. Some further details of these studies are shown in Supplementary Table S1.…”

The modified arterial reservoir: an update with consideration of asymptotic pressure (P∞) and zero-flow pressure (Pzf)

“…Data are shown as means (95% confidence intervals).A total of 1255 unique publications were identified after removal of duplicates; 1235were excluded during screening. The remaining 20 studies(48)(49)(50)(51)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66)(67)(68)(69) with Pzf data were included in a meta-analysis (Figure 2); these included data from dog, rat, pig and human; 8 of these articles also provided data on MCFP from the same studies. Some further details of these studies are shown inSupplementary Table S1.From this analysis Pzf = 26.5 (23.4, 29.5) mmHg (Figure 3; 20 studies; mean (95% confidence interval); n = 311; I 2 = 97%; P <0.001) and MCFP = 10.6 (9.3, 12.0) mmHg (8 studies; n = 178; I 2 = 96%; p < 0.001).…”