Therapeutic control of the circulation

Parkin, W. G.; Leaning, M.S.

doi:10.1007/s10877-008-9147-7

Cited by 85 publications

(89 citation statements)

References 12 publications

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“…1. The Pmsa estimate [9] uses a mathematical model of the systemic circulation comprising compliant arterial and venous compartments and resistances to blood flow. The model parameters are adjusted to match those of the patient’s current measured variables, such that Pmsa = a × Pcv + b × Pa + c × CO, where a and b are dimensionless constants ( a + b = 1, typically a = 0.96, b = 0.04) and c has the dimensions of resistance and is function of subject’s height, weight, and age.…”

Section: Methodsmentioning

confidence: 99%

“…This technique has the advantage of being simpler than the inspiratory hold technique but still can be measured only intermittently. Similarly, Parkin and Leaning [9] proposed to estimate effective circulatory volume based on an electrical analog simplification of Guytonian circulatory physiology estimating mean circulatory pressure (Pmsa) from directly measured Pra, mean arterial pressure (MAP), and CO. We recently compared the measures of Pms using inspiratory hold, Parm and Pmsa, to each other in 16 postoperative surgical patients [10]. We saw that inspiratory hold–derived Pms and Parm were similar but that Pmsa displayed a systematic bias, which could be corrected for.…”

Section: Introductionmentioning

confidence: 99%

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Effect of acute endotoxemia on analog estimates of mean systemic pressure

Lee

Ogundele

Pike

et al. 2013

Journal of Critical Care

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Dynamic estimates of mean systemic pressure based on a Guytonian analog model (Pmsa) appear accurate under baseline conditions but may not remain so during septic shock because blood volume distribution and resistances between arterial and venous beds may change. Thus, we examined the effect of acute endotoxemia on the ability of Pmsa, estimated from steady-state cardiac output, right atrial pressure, and mean arterial pressure, to reflect our previously validated instantaneous venous return measure of mean systemic pressure (Pmsi), derived from beat-to-beat measures of right ventricular stroke volume and right atrial pressure during positive pressure ventilation. We studied 6 splenectomized pentobarbital-anesthetized close chested dogs. Right ventricular stroke volume was measured by a pulmonary arterial electromagnetic flow probe. Instantaneous venous return measure of mean systemic pressure and Pmsa were calculated during volume loading and removal (±100-mL bolus increments ×5) both before (control) and 30 minutes after endotoxin infusion (endo). Cardiac output increased (2628 ± 905 vs 3560 ± 539 mL/min; P < .05) and mean arterial pressure decreased (107 ± 16 vs 56 ± 12 mm Hg; P < .01) during endo. Changes in Pmsi and Pmsa correlated during both control and endo (r2 = 0.7) with minimal bias by Bland-Altman analysis (mean difference ± 95% confidence interval, 0.47 ± 5.04 mm Hg). We conclude that changes in Pmsa accurately tracts Pmsi under both control and endo.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of acute endotoxemia on analog estimates of mean systemic pressure

Lee

Ogundele

Pike

et al. 2013

Journal of Critical Care

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“…Pmsa calculation is based on the values of CO, CVP, mean arterial pressure (MAP), and patient's anthropometric measures (height, weight and age) (21,22).…”

Section: Determination Of Pmsf-analogue: Pmsamentioning

confidence: 99%

Pharmacodynamic Analysis of a Fluid Challenge

Aya

Ster

Fletcher

et al. 2016

Critical Care Medicine

106

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Objective: This study aims to describe the pharmacodynamics (PD) of a fluid challenge over a ten-minute period in post-operative patients. Design: Prospective observational studySetting: General and cardiothoracic intensive care unit, tertiary hospital.Patients: 26 post-operative patients.Intervention: 250 ml fluid challenge performed over 5 minutes. Data was recorded over 10 minutes after the end of fluid infusion Measurements and main results: Cardiac output (CO) was measured with a calibratedLiDCOplus™ (LiDCO, UK) and Navigator™ (Applied Physiology, Australia) to obtain the Pmsf analogue (Pmsa). PD outcomes were modelled using a Bayesian inferential approach and Markov chain Monte Carlo estimation methods. Parameter estimates were summarized as the means of their posterior distributions and their uncertainty was assessed by the 95% Credible Intervals (CrI). Bayesian probabilities for groups' effect were also derived. The predicted maximal effect on CO was observed at 1.2 minutes (95% CrIo.6 to 2.8) in responders. The probability that the estimated area under the curve of central venous pressure (CVP) was smaller in non-responders was 0.12. (estimated difference -4.91 mmHg·min (95% CrI -13.45 to 3.3). After 10 minutes, there is no evidence of a difference between groups for any haemodynamic variable. Conclusion:The maximal change in CO should be assessed one minute after the end of the fluid infusion. The global effect of the fluid challenge on CVP is greater in nonPharmacodynamics of a fluid challenge 3 responders but not its change ten minutes after the fluid infusion. The effect of a fluid challenge on hemodynamics is dissipated in ten minutes similarly in both groups. Pharmacodynamics of a fluid challenge 4

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“…Importantly, Parkin and Leaning used a mathematical modeling technique to develop an algorithm for estimating an analogous value of Pms from commonly measured hemodynamic variables without stopping the heart. With this technique, one can accurately and continuously measure Pms, as an analogue construct, referred to as Pmsa (8). By knowing both Pmsa and Pra, one can define cardiac performance (heart efficiency, Eh) as the ratio dVR/Pms, with a perfect heart having an Eh of 1.…”

mentioning

confidence: 99%