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BP and HR Interactions: Assessment of Spontaneous Baroreceptor Reflex Sensitivity
Published in Herbert F. Jelinek, David J. Cornforth, Ahsan H. Khandoker, ECG Time Series Variability Analysis, 2017
Tatjana Lončar-Turukalo, Nina Japundžić-Žigon, Olivera Šarenac, Dragana Bajić
This first technique to assess BRS used in physiology was developed by Smyth in 1969. The Oxford method introduced by Smyth induces the increase in BP by bolus injections of vasoactive medication phenylephrine with minimal effect on the sinoatrial node. This method is focused on the HR BRR branch and measures changes in RRIs provoked by induced changes in BP. The limitation of the Oxford method is that only vasoconstrictors are used, exploring only a limited part of the RR–SBP sigmoidal curve and mainly the vagal component of the BRR. The modified Oxford method introduced the use of vasodilators to produce a fall in the BP and a response of the sinoatrial node partly mediated by sympathetic branches (Rudas et al. 1999). BRS is estimated by the means of linear regression between SBP and one-beat-delayed RRI values in the time span between the beginning and the end of the induced change in BP.
Blood pressure response simulator to vasopressor drug infusion (PressorSim)
Published in International Journal of Control, 2021
Guoyan Cao, Karolos M. Grigoriadis
Vasopressors (or pressors) are intravenous drugs that are administered in critical care to increase and regulate the blood pressure of hypotensive patients to restore perfusion and achieve hemodynamic stability (Herget-Rosenthal et al., 2008). Pressors, such as phenylephrine (PHP), epinephrine, ephedrine and norepinephrine, raise reduced blood pressure by acting as vasoconstrictors to increase total peripheral resistance. They are used for resuscitation of critical patients suffering from haemorrhage, spinal cord injury, septic shock, traumatic brain injury, severe burn or other critical hypotensive conditions (Hollenberg, 2007). Accurate administration of pressors is essential to achieve adequate cardiac output without drug overdosing that could lead to tachycardia and cardiac arrest. Resuscitation is achieved by seeking to regulate the patient’s mean arterial pressure (MAP) to target values by appropriate intravenous pressor infusion via volumetric bolus injections (Flancbaum et al., 1997). Pressor administration is significantly complicated by the fact that responsiveness to the drug is vastly varying from patient to patient (inter-patient variability), as well as, as within a given patient over time (intra-patent variability) due to varying human physiology (Ortiz & Garvin, 2001). Hence, the resuscitation of hypovolemic patients by medical personnel using pressors is a challenging process, especially in a critical care environment where dedicated medical attention is often sparse.