Combining Physiology-Based Modeling and Evolutionary Algorithms for Personalized, Noninvasive Cardiovascular Assessment Based on Electrocardiography and Ballistocardiography

Purpose: This study proposes a novel approach to obtain personalized estimates of cardiovascular parameters by combining (i) electrocardiography and ballistocardiography for noninvasive cardiovascular monitoring, (ii) a physiology-based mathematical model for predicting personalized cardiovascular variables, and (iii) an evolutionary algorithm (EA) for searching optimal model parameters.Methods: Electrocardiogram (ECG), ballistocardiogram (BCG), and a total of six blood pressure measurements are recorded on three healthy subjects. The R peaks in the ECG are used to segment the BCG signal into single BCG curves for each heart beat. The time distance between R peaks is used as an input for a validated physiology-based mathematical model that predicts distributions of pressures and volumes in the cardiovascular system, along with the associated BCG curve. An EA is designed to search the generation of parameter values of the cardiovascular model that optimizes the match between model-predicted and experimentally-measured BCG curves. The physiological relevance of the optimal EA solution is evaluated a posteriori by comparing the model-predicted blood pressure with a cuff placed on the arm of the subjects to measure the blood pressure.Results: The proposed approach successfully captures amplitudes and timings of the most prominent peak and valley in the BCG curve, also known as the J peak and K valley. The values of cardiovascular parameters pertaining to ventricular function can be estimated by the EA in a consistent manner when the search is performed over five different BCG curves corresponding to five different heart-beats of the same subject. Notably, the blood pressure predicted by the physiology-based model with the personalized parameter values provided by the EA search exhibits a very good agreement with the cuff-based blood pressure measurement.Conclusion: The combination of EA with physiology-based modeling proved capable of providing personalized estimates of cardiovascular parameters and physiological variables of great interest, such as blood pressure. This novel approach opens the possibility for developing quantitative devices for noninvasive cardiovascular monitoring based on BCG sensing.

Penanganan Trigeminocardiac Reflex (TCR) selama Anestesi untuk Bedah Saraf

Trigeminocardiac reflex (TCR) is a unique brain stem reflex that manifests as negative cardio-respiratory perturbations. The trigeminocardiac reflex (TCR) is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve. Clinically, the TCR has been reported in all the surgical procedures in which a structure innervated by the trigeminal nerve is involved. This reflex is largely reported in skull base surgeries/interventions; however, in recent times, it has been also linked with many neurosurgical, neurointerventional procedures, non-neurosurgical and non-surgical conditions. This reflex presents with many cardiovascular changes that can create catastrophic complications, worse outcome as well as diagnostic dilemmas. Although, there is an abundant literature with reports of incidences and risk factors of the TCR; the physiological significance and function of this brainstem reflex has not yet been fully elucidated. In addition, there are complexities within the TCR that requires examination and clarification. If a CTR occurs, it can risk factor identification and modification, depth of anesthesia assessment, prophylactic treatment with either vagolytic agents or peripheral nerve block in case of peripheral manipulations of the nerve, careful cardiovascular monitoring during anesthesia, especially in those with a risk factor for TCR, treatment of the condition when it occurs: cessation of the manipulation, and administration of vagolytic agents and adrenaline. Therefore, this narrative review intends to elaborate on its mechanisms, definition, pathophysiology, manifestations, diagnosis and management.