https://nova.newcastle.edu.au/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/manager/Repository/uon:22494 Thu 22 Sep 2016 11:23:39 AEST ]]> https://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12659 Thu 03 Sep 2020 09:11:29 AEST ]]> https://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12892 Sat 24 Mar 2018 08:17:13 AEDT ]]> https://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12668 z) has been controversial. This could be, in part, due to the use in the Kubicek formula of the bench-determined blood resistivity (p)-haematocrit (Hct) relationship, which does not take into account factors such as complex blood-velocity movements. In the present study in vivo, p was calculated in dog, rabbit and man from the rearranged Kubicek formula, p = (SV. Zo²)/(L². dZ/dt max T); the stroke volumes used in the calculation being derived at different Hcts in the different species from the independent techniques of electromagnetic flowmeter, direct Fick, and direct Fick and thermodilution, respectively. The in vivo p-Hct relationship is linear, inverse and nearly constant over the range of Hcts tested (dog 26–62%, man 31–48%, rabbit 37%). No significant difference exists between meanin vivo p values determined for the three species at corresponding haematocrits despite different thoracic anatomy and circulatory dynamics. Thus, the best estimate of mean p in vivo within the normal Hct range is 135Ωcm, the use of which will result in a SV_z accuracy of better than ± 10%.]]> Sat 24 Mar 2018 08:15:49 AEDT ]]> https://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12664 τ) has been calculated in dogs from the rearranged Kubicek formula: p_τ = (SV · Z₀²)/(L² dZ/dt_max·T), where SV was measured by the electromagnetic flowmeter (EM). Hematocrit (Hct) in the dog was varied by hemorrhage and infusion. In contrast to the direct and exponential bench p-Hct relationship, p_τ varies inversely with Hct, but by no more than +6.3 Ω · cm (at Hct 26%) and -11.8 Ω · cm (at Hct 66%) about a mean p_τ of 135 ± 1.0 Ω · cm (at Hct 40%). Impedance SV calculated using p_τ over a wide range of SV bears a linear relationship to EM values with a 95% prediction limit for a single SV estimate of ±0.84 about a mean value of 26.9 ml. The findings suggest that p_τ is virtually constant during a variety of physiological disturbances.]]> Fri 27 Sep 2019 16:12:28 AEST ]]>