title: Baroreflex sensitivity variations in response to propofol anesthesia: comparison between normotensive and hypertensive patients.
abstract: The aim of this paper is to compare baroreflex sensitivity (BRS) following anesthesia induction via propofol to pre-induction baseline values through a systematic and mathematically robust analysis. Several mathematical methods for BRS quantification were applied to pre-operative and intra-operative data collected from patients undergoing major surgery, in order to track the trend in BRS variations following anesthesia induction, as well as following the onset of mechanical ventilation. Finally, a comparison of BRS trends in chronic hypertensive patients (CH) with respect to non hypertensive (NH) patients was performed. 10 NH and 7 CH patients undergoing major surgery with American Society of Anesthesiologists classification score 2.5 ± 0.5 and 2.6 ± 0.5 respectively, were enrolled in the study. A Granger causality test was carried out to verify the causal relationship between RR interval duration and systolic blood pressure (SBP), and four different mathematical methods were used to estimate the BRS: (1) ratio between autospectra of RR and SBP, (2) transfer function, (3) sequence method and (4) bivariate closed loop model. Three different surgical epochs were considered: baseline, anesthetic procedure and post-intubation. In NH patients, propofol administration caused a decrease in arterial blood pressure (ABP), due to its vasodilatory effects, and a reduction of BRS, while heart rate (HR) remained unaltered with respect to baseline values before induction. A larger decrease in ABP was observed in CH patients when compared to NH patients, whereas HR remained unaltered and BRS was found to be lower than in the NH group at baseline, with no significant changes in the following epochs when compared to baseline. To our knowledge, this is the first study in which the autonomic response to propofol induction in CH and NH patients was compared. The analysis of BRS through a mathematically rigorous procedure in the perioperative period could result in the availability of additional information to guide therapy and anesthesia in uncontrolled hypertensive patients, which are prone to a higher rate of hypotension events occurring during general anesthesia induction.
authors: Department of Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milan, MI, Italy.
authors: Guadalupe
authors: G
authors: Dorantes Mendez
authors: Federico
authors: F
authors: Aletti
authors: Nicola
authors: N
authors: Toschi
authors: Antonio
authors: A
authors: Canichella
authors: Mario
authors: M
authors: Dauri
authors: Filadelfo
authors: F
authors: Coniglione
authors: Maria
authors: M
authors: Guerrisi
authors: Maria G
authors: MG
authors: Signorini
authors: Sergio
authors: S
authors: Cerutti
authors: Manuela
authors: M
authors: Ferrario
mesh_terms: D000368:Aged; D000465:Algorithms; D000758:Anesthesia / Q000379:methods*; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D062186:Arterial Pressure / Q000187:drug effects; D017704:Baroreflex / Q000187:drug effects* / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D015742:Propofol / Q000008:administration & dosage*; D013997:Time Factors
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol