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Stuart D Katz - One of the best experts on this subject based on the ideXlab platform.
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subacute pyridostigmine exposure increases heart rate recovery and cardiac Parasympathetic Tone in rats
Clinical and Experimental Pharmacology and Physiology, 2017Co-Authors: Manushree Bharadwaj, Stuart D Katz, Carey Pope, Michael S Davis, Christian Cook, Lara K MaxwellAbstract:Heart rate recovery (HRR) describes the rapid deceleration of heart rate after strenuous exercise and is an indicator of Parasympathetic Tone. A reduction in Parasympathetic Tone occurs in patients with congestive heart failure, resulting in prolonged HRR. Acetylcholinesterase inhibitors, such as pyridostigmine, can enhance Parasympathetic Tone by increasing cholinergic input to the heart. The objective of this study was to develop a rodent model of HRR to test the hypothesis that subacute pyridostigmine administration decreases cholinesterase activity and accelerates HRR in rats. Ten days after implantation of radiotelemetry transmitters, male Sprague Dawley rats were randomized to control (CTL) or treated (PYR; 0.14 mg/ml pyridostigmine in the drinking water, 29 days) groups. Rats were exercised on a treadmill to record HRR, and blood samples were collected on days 0, 7, 14, and 28 of pyridostigmine administration. Total cholinesterase and acetylcholinesterase (AChE) activity in plasma was decreased by 32-43% and 57-80%, respectively, in PYR rats on days 7-28, while plasma butyrylcholinesterase activity did not significantly change. AChE activity in RBCs was markedly reduced by 64-66%. HRR recorded 1 min after exercise was higher in the PYR group on days 7, 14 and 28, and on day 7 when HRR was estimated at 3 and 5 min. Autonomic Tone was evaluated pharmacologically using sequential administration of muscarinic (atropine) and adrenergic (propranolol) blockers. Parasympathetic Tone was increased in PYR rats as compared with the CTL group. These data support the study hypothesis that subacute pyridostigmine administration enhances HRR by increasing cardiac Parasympathetic Tone. This article is protected by copyright. All rights reserved.
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subacute pyridostigmine exposure increases heart rate recovery and cardiac Parasympathetic Tone in rats
Clinical and Experimental Pharmacology and Physiology, 2017Co-Authors: Manushree Bharadwaj, Stuart D Katz, Michael S Davis, Christian Cook, C N Pope, Lara K MaxwellAbstract:Heart rate recovery (HRR) describes the rapid deceleration of heart rate after strenuous exercise and is an indicator of Parasympathetic Tone. A reduction in Parasympathetic Tone occurs in patients with congestive heart failure, resulting in prolonged HRR. Acetylcholinesterase inhibitors, such as pyridostigmine, can enhance Parasympathetic Tone by increasing cholinergic input to the heart. The objective of this study was to develop a rodent model of HRR to test the hypothesis that subacute pyridostigmine administration decreases cholinesterase activity and accelerates HRR in rats. Ten days after implantation of radiotelemetry transmitters, male Sprague Dawley rats were randomized to control (CTL) or treated (PYR; 0.14 mg/mL pyridostigmine in the drinking water, 29 days) groups. Rats were exercised on a treadmill to record HRR, and blood samples were collected on days 0, 7, 14, and 28 of pyridostigmine administration. Total cholinesterase and acetylcholinesterase (AChE) activity in plasma was decreased by 32%-43% and 57%-80%, respectively, in PYR rats on days 7-28, while plasma butyrylcholinesterase activity did not significantly change. AChE activity in red blood cells was markedly reduced by 64%-66%. HRR recorded 1 minute after exercise was higher in the PYR group on days 7, 14 and 28, and on day 7 when HRR was estimated at 3 and 5 minutes. Autonomic Tone was evaluated pharmacologically using sequential administration of muscarinic (atropine) and adrenergic (propranolol) blockers. Parasympathetic Tone was increased in PYR rats as compared with the CTL group. These data support the study hypothesis that subacute pyridostigmine administration enhances HRR by increasing cardiac Parasympathetic Tone.
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effect of acetylcholinesterase inhibition with pyridostigmine on cardiac Parasympathetic function in sedentary adults and trained athletes
American Journal of Physiology-heart and Circulatory Physiology, 2007Co-Authors: Thomas A Dewland, Ana Silvia Androne, Rachel Lampert, Stuart D KatzAbstract:Heart rate variability and postexercise heart rate recovery are used to assess cardiac Parasympathetic Tone in human studies, but in some cases these indexes appear to yield discordant information....
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effect of acetylcholinesterase inhibition with pyridostigmine on cardiac Parasympathetic function in sedentary adults and trained athletes
American Journal of Physiology-heart and Circulatory Physiology, 2007Co-Authors: Thomas A Dewland, Ana Silvia Androne, Forrester A Lee, Rachel Lampert, Stuart D KatzAbstract:Heart rate variability and postexercise heart rate recovery are used to assess cardiac Parasympathetic Tone in human studies, but in some cases these indexes appear to yield discordant information. We utilized pyridostigmine, an acetylcholinesterase inhibitor that selectively augments the Parasympathetic efferent signal, to further characterize Parasympathetic regulation of rest and postexercise heart rate. We measured time- and frequency-domain indexes of resting heart rate variability and postexercise heart rate recovery in 10 sedentary adults and 10 aerobically trained athletes after a single oral dose of pyridostigmine (30 mg) and matching placebo in randomized, double-blind, crossover trial. In sedentary adults, pyridostigmine decreased resting heart rate [from 66.7 (SD 12.6) to 58.1 beats/min (SD 7.6), P = 0.005 vs. placebo] and increased postexercise heart rate recovery at 1 min [from 40.7 (SD 10.9) to 45.1 beats/min (SD 8.8), P = 0.02 vs. placebo]. In trained athletes, pyridostigmine did not change resting heart rate or postexercise heart rate recovery when compared with placebo. Time- and frequency-domain indexes of resting heart rate variability did not differ after pyridostigmine versus placebo in either cohort and were not significantly associated with postexercise heart rate recovery in either cohort. The divergent effects of pyridostigmine on resting and postexercise measures of cardiac Parasympathetic function in sedentary subjects confirm that these measures characterize distinct aspects of cardiac Parasympathetic regulation. The lesser effect of pyridostigmine on either measure of cardiac Parasympathetic Tone in the trained athletes indicates that the enhanced Parasympathetic Tone associated with exercise training is at least partially attributable to adaptations in the efferent Parasympathetic pathway.
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acetylcholinesterase inhibition with pyridostigmine improves heart rate recovery after maximal exercise in patients with chronic heart failure
Heart, 2003Co-Authors: Ana Silvia Androne, Katarzyna Hryniewicz, Rochelle L Goldsmith, A Arwady, Stuart D KatzAbstract:Objective: To characterise the effects of acetylcholinesterase inhibition with pyridostigmine on Parasympathetic Tone in patients with chronic heart failure (CHF). Design: Prospective randomised, double blind crossover trial. Setting: University hospital outpatient heart failure clinic. Patients: 20 ambulatory subjects with stable CHF (mean age 55 years, mean ejection fraction 24%). Interventions: Oral administration of a single dose of pyridostigmine 30 mg and matching placebo on separate days. Main outcome measures: Heart rate recovery at one minute and three minutes after completion of maximal exercise. Results: Heart rate recovery at one minute after exercise was significantly greater after administration of pyridostigmine than after administration of placebo (mean (SEM) 27.4 (3.2) beats/min v 22.4 (2.4) beats/min, p < 0.01). Heart rate recovery at three minutes after exercise did not differ after administration of pyridostigmine and placebo (mean (SEM) 44.4 (3.9) beats/min v 41.8 (3.6) beats/ min, NS). Peak heart rate, peak oxygen uptake, peak respiratory exchange ratio, plasma noradrenaline (norepinephrine) concentrations, and plasma brain natriuretic peptide concentrations did not differ after administration of pyridostigmine and placebo. Conclusions: Acetylcholinesterase inhibition with pyridostigmine increased heart rate recovery at one minute but not at three minutes after exercise. A specific effect of pyridostigmine on heart rate one minute after exercise suggests that pyridostigmine augments Parasympathetic Tone in patients with CHF.
Robert J Cody - One of the best experts on this subject based on the ideXlab platform.
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sustained augmentation of Parasympathetic Tone with angiotensin converting enzyme inhibition in patients with congestive heart failure
Journal of the American College of Cardiology, 1993Co-Authors: Philip F Binkley, Garrie J Haas, Randall C Starling, Enrico Nunziata, Patricia A Hatton, Carl V Leier, Robert J CodyAbstract:Abstract Objectives. The objective of this investigation was to evaluate the changes in Parasympathetic Tone associated with long-term angiotensin-converting enzyme inhibitor therapy in patients with congestive heart failure. Background. Angiotensin-converting enzyme inhibitors provide hemodynamic and symptomatic benefit and are associated with improved survivel in patients with congestive heart failure. Angiotensin II, whose production is ultimately inhibited by these agents, exerts significant regulatory influence on a variety of target organs including the central and peripheral nervous systems. Accordingly, it would be anticipated that angiotensin-converting enzyme inhibitors would significantly alter the autonomic imbalance characteristic of patients with congestive heart failure and that this influence over neural mechanisms of cardiovascular control may significantly contribute to the hemodynamic benefit and improved survival associated with angiotensin-converting enzyme inhibitor therapy. Methods. In the current investigation, changes in autonomic Tone associated with long-term administration of an angiotensin-converting enzyme inhibitor were measured using spectral analysis of heart rate variability in 13 patients with congestive heart failure who were enrolled in a double-blind randomized placebo-controlled trial of the angiotensin-converting enzyme inhibitor zofenopril. Both placebo and treatment groups were balanced at baseline study in terms of functional class, ventricular performance and autonomic Tone. Results. After 12 weeks of therapy with placebo, there was no change in total heart rate variability, Parasympathetically governed high frequency heart rate variability or sympathetically influenced low frequency heart rate variability. In contrast, therapy with zofenopril was associated with a 50% increase in total heart rate variability (p = 0.09) and a significant (p = 0.03) twofold increase in high frequency heart rate variability, indicating a significant augmentation of Parasympathetic Tone. Conclusions. These results demonstrate that long-term treatment of patients having congestive heart failure with an angiotensin-converting enzyme inhibitor is associated with a restoration of autonomic balance, which derives in part from a sustained augmentation of Parasympathetic Tone. Such augmentation of vagal Tone is known to be protective against malignant ventricular arrhythmias in patients with ischemic heart disease and therefore may have similar benefit in the setting of ventricular failure, thus contributing to the improved survival associated with angiotensin-converting enzyme inhibitor therapy in patients with congestive heart failure.
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Parasympathetic withdrawal is an integral component of autonomic imbalance in congestive heart failure demonstration in human subjects and verification in a paced canine model of ventricular failure
Journal of the American College of Cardiology, 1991Co-Authors: Philip F Binkley, Garrie J Haas, Enrico Nunziata, Steven D Nelson, Robert J CodyAbstract:Abstract Although enhanced sympathetic Tone is a well recognized component of the autonomic profile characteristic of congestive heart failure, the contribution of Parasympathetic withdrawal to this autonomic imbalance is less well described. The technique of spectral analysis of heart rate variability provides a dynamic map of sympathetic and Parasympathetic Tone and was thus used to define the nature of sympathetic-Parasympathetic interactions in humans with idiopathk dilated cardiomyopathy and in a paced canine model of congestive heart failure. Humans with cardiomyopathy were found to have an augmentation of the sympathetically mediated low frequency area of the power density spectrum. Parasympathetic withdrawal was demonstrated by significant reductions in the Parasympathetically mediated high frequency area (p Induction of congestive heart failure in a paced canine model resulted in alterations in the autonomic profile that resembled those seen in humans with ventricular failure. The prominent high frequency region of the spectrum at baseline, indicating a predominance of Parasympathetic Tone, was absent after the evolution of congestive heart failure, and there was a marked augmentation of the low frequency region of the spectrum. These observations indicate that Parasympathetic withdrawal, in addition to the well known augmentation of sympathetic drive, is an integral component of the autonomic imbalance characteristic of chronic congestive heart failure and can be detected noninvasively by spectral analysis of heart rate variability. Furthermore, enhanced sympathetic stimulation alone does not reproduce this characteristic profile, as evidenced by the isoproterenol-induced changes in the power density spectrum in normal subjects.
Paul Grossman - One of the best experts on this subject based on the ideXlab platform.
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cardiac autonomic mechanisms associated with borderline hypertension under varying behavioral demands evidence for attenuated Parasympathetic Tone but not for enhanced beta adrenergic activity
Psychophysiology, 2007Co-Authors: Paul Grossman, Annemiek Brinkman, Johan De VriesAbstract:Elevated blood pressure in psychophysiological studies of borderline hypertension is frequently attributed to the effects of increased sympathetic Tone, and with few exceptions, the potential Parasympathetic contributions have not been considered. Furthermore, of the investigations that have addressed vagal influences upon blood pressure, most have employed invasive pharmacological assessment of Parasympathetic Tone. In this study, cardiac Parasympathetic and beta-adrenergic influences in borderline hypertension were evaluated noninvasively employing respiratory sinus arrhythmia as a vagal index and pree-jection period as a sympathetic index of cardiac functioning. Subjects were 30 borderline hypertensive and 23 normotensive males (age range, 24–45 years). The ECG, blood pressure, impedance cardiography, and respiration were measured during two baselines (initial and post-task), a memory-comparison reaction time task, the cold pressor, and CO2-rebreathing. Results indicated tonic differences between groups in all cardiovascular variables across tasks, with the exception of pre-ejection period, which showed no group effects at all. Hypertensives additionally manifested somewhat heightened systolic blood pressure reactivity and attenuated cardiac Parasympathetic responsivity to specific tasks. Our findings provide no support for an exaggerated cardiac beta-adrenergic tonic level or reactivity in borderline hypertensives. On the other hand, the consistently lower magnitude of respiratory sinus arrhythmia in our hypertensives suggests that reduced Parasympathetic control may be involved in the pathophysiology of hypertension.
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respiratory sinus arrhythmia cardiac vagal Tone and respiration within and between individual relations
Psychophysiology, 1993Co-Authors: Paul Grossman, Mark KollaiAbstract:Respiratory sinus arrhythmia (RSA) is frequently employed as an intra- and interindividual index of cardiac Parasympathetic Tone, although the relationship of RSA to interindividual differences in cardiac vagal Tone remains questionable. Our study examined between- and within-subject relations among RSA, cardiac vagal Tone, and respiratory parameters. Twenty-nine young adults performed two sessions of tasks under no medication and single and double autonomic blockade (intravenously administered propranolol and atropine). Parasympathetic Tone was determined from heart period responses to complete vagal blockade. Results indicated the following. Resting RSA does not accurately predict individual differences in cardiac vagal Tone. However, RSA and heart period together do predict such individual differences reasonably well. The relationship between individual variations in RSA and vagal Tone is not improved by controlling respiratory parameters. Substantial cardiac vagal activity occurs during inspiration, and intraindividual variations in respiratory measures confound the association between RSA and cardiac vagal Tone.
Philip F Binkley - One of the best experts on this subject based on the ideXlab platform.
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sustained augmentation of Parasympathetic Tone with angiotensin converting enzyme inhibition in patients with congestive heart failure
Journal of the American College of Cardiology, 1993Co-Authors: Philip F Binkley, Garrie J Haas, Randall C Starling, Enrico Nunziata, Patricia A Hatton, Carl V Leier, Robert J CodyAbstract:Abstract Objectives. The objective of this investigation was to evaluate the changes in Parasympathetic Tone associated with long-term angiotensin-converting enzyme inhibitor therapy in patients with congestive heart failure. Background. Angiotensin-converting enzyme inhibitors provide hemodynamic and symptomatic benefit and are associated with improved survivel in patients with congestive heart failure. Angiotensin II, whose production is ultimately inhibited by these agents, exerts significant regulatory influence on a variety of target organs including the central and peripheral nervous systems. Accordingly, it would be anticipated that angiotensin-converting enzyme inhibitors would significantly alter the autonomic imbalance characteristic of patients with congestive heart failure and that this influence over neural mechanisms of cardiovascular control may significantly contribute to the hemodynamic benefit and improved survival associated with angiotensin-converting enzyme inhibitor therapy. Methods. In the current investigation, changes in autonomic Tone associated with long-term administration of an angiotensin-converting enzyme inhibitor were measured using spectral analysis of heart rate variability in 13 patients with congestive heart failure who were enrolled in a double-blind randomized placebo-controlled trial of the angiotensin-converting enzyme inhibitor zofenopril. Both placebo and treatment groups were balanced at baseline study in terms of functional class, ventricular performance and autonomic Tone. Results. After 12 weeks of therapy with placebo, there was no change in total heart rate variability, Parasympathetically governed high frequency heart rate variability or sympathetically influenced low frequency heart rate variability. In contrast, therapy with zofenopril was associated with a 50% increase in total heart rate variability (p = 0.09) and a significant (p = 0.03) twofold increase in high frequency heart rate variability, indicating a significant augmentation of Parasympathetic Tone. Conclusions. These results demonstrate that long-term treatment of patients having congestive heart failure with an angiotensin-converting enzyme inhibitor is associated with a restoration of autonomic balance, which derives in part from a sustained augmentation of Parasympathetic Tone. Such augmentation of vagal Tone is known to be protective against malignant ventricular arrhythmias in patients with ischemic heart disease and therefore may have similar benefit in the setting of ventricular failure, thus contributing to the improved survival associated with angiotensin-converting enzyme inhibitor therapy in patients with congestive heart failure.
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Parasympathetic withdrawal is an integral component of autonomic imbalance in congestive heart failure demonstration in human subjects and verification in a paced canine model of ventricular failure
Journal of the American College of Cardiology, 1991Co-Authors: Philip F Binkley, Garrie J Haas, Enrico Nunziata, Steven D Nelson, Robert J CodyAbstract:Abstract Although enhanced sympathetic Tone is a well recognized component of the autonomic profile characteristic of congestive heart failure, the contribution of Parasympathetic withdrawal to this autonomic imbalance is less well described. The technique of spectral analysis of heart rate variability provides a dynamic map of sympathetic and Parasympathetic Tone and was thus used to define the nature of sympathetic-Parasympathetic interactions in humans with idiopathk dilated cardiomyopathy and in a paced canine model of congestive heart failure. Humans with cardiomyopathy were found to have an augmentation of the sympathetically mediated low frequency area of the power density spectrum. Parasympathetic withdrawal was demonstrated by significant reductions in the Parasympathetically mediated high frequency area (p Induction of congestive heart failure in a paced canine model resulted in alterations in the autonomic profile that resembled those seen in humans with ventricular failure. The prominent high frequency region of the spectrum at baseline, indicating a predominance of Parasympathetic Tone, was absent after the evolution of congestive heart failure, and there was a marked augmentation of the low frequency region of the spectrum. These observations indicate that Parasympathetic withdrawal, in addition to the well known augmentation of sympathetic drive, is an integral component of the autonomic imbalance characteristic of chronic congestive heart failure and can be detected noninvasively by spectral analysis of heart rate variability. Furthermore, enhanced sympathetic stimulation alone does not reproduce this characteristic profile, as evidenced by the isoproterenol-induced changes in the power density spectrum in normal subjects.
Stephane Junot - One of the best experts on this subject based on the ideXlab platform.
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performance of the Parasympathetic Tone activity pta index to predict changes in mean arterial pressure in anaesthetized horses with different health conditions
Research in Veterinary Science, 2021Co-Authors: Christelle Mansour, Emmanuel Boselli, Bernard Allaouchiche, Rana Chaaya, Rita Mocci, Bruna Santangelo, Jerneja Sredensek, Jeannemarie Bonnetgarin, Stephane JunotAbstract:Abstract The Parasympathetic Tone activity (PTA) index is based on heart rate variability and has been developed recently in animals to assess their relative Parasympathetic Tone. This study aimed to evaluate PTA index in anaesthetized horses with different health conditions and the performance of PTA variations (∆PTA) to predict changes in mean arterial pressure (MAP). Thirty-nine client-horses were anaesthetized for elective or colic surgery and divided into “Elective” and “Colic” groups. During anaesthesia, dobutamine was administered as treatment of hypotension (MAP In both groups, no significant variation of PTA and MAP were detected immediately before and after cutaneous incision. The PTA index increased 5 min before each hypotension, whereas it decreased 1 min after dobutamine administration. Horses of the Colic group had lower PTA values than those of the Elective group, whereas MAP did not differ between groups. To predict a 10% decrease in MAP, ΔPTA performance was associated with: AUC ROC [95% CI] =0.80 [0.73 to 0.85] (p The PTA index in anaesthetized horses appears to be influenced by the health condition. The shift toward lower PTA values in colic horses may reflect a sympathetic predominance. An increase in PTA of >25% in 1 min showed an acceptable performance to predict MAP decrease of >10% within 5 min. Even though these results require further evaluation, this index may thus help to predict potential autonomic dysfunctions in sick animals.
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performance of the Parasympathetic Tone activity pta index to assess the intraoperative nociception using different premedication drugs in anaesthetised dogs
International Journal of Veterinary Science and Medicine, 2020Co-Authors: Christelle Mansour, Nour El Hachem, Patrick Jamous, Georges Saade, Emmanuel Boselli, Bernard Allaouchiche, Jeannemarie Bonnet, Stephane Junot, Rana ChaayaAbstract:The dynamic variations of the Parasympathetic Tone Activity (PTA) index were evaluated to assess nociception in dogs undergoing anaesthetic protocols with different premedication drugs. Sixty-six d...
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evaluation of the Parasympathetic Tone activity pta index to assess the analgesia nociception balance in anaesthetised dogs
Research in Veterinary Science, 2017Co-Authors: Christelle Mansour, Emmanuel Boselli, Bernard Allaouchiche, Rana Chaaya, Rita Mocci, Jeannemarie Bonnetgarin, Tristan Merlin, Clara Conde Ruiz, Stephane JunotAbstract:The Parasympathetic Tone Activity (PTA) is an index based on the analysis of heart rate variability that has been recently developed to assess the analgesia/nociception balance in anaesthetised animals. The present study aimed to evaluate its performance in dogs undergoing surgery. Thirty dogs admitted for elective surgeries, were anaesthetised with a standardised protocol. PTA, heart rate (HR), systolic blood pressure (SBP) and HDR (defined as an increase by >20% in HR and/or SBP within 5min) were assessed at the following predefined time-points: TStSt (steady-state, after induction of anaesthesia and before start of surgery), TClamp (clamping of surgical drapes on the skin), TCut (cutaneous incision), TPrePTA (retrospectively assessed 1min before a PTA decline of at least 20%) and TEndIso (isoflurane discontinuation). The dynamic variation of PTA over 1min (∆PTA) was calculated at each predefined time-points and its performance to predict HDR was assessed by building Receiver Operating Characteristics (ROC) curves. A significant decrease of PTA (p<0.002) was detected 1min after TClamp, TCut and TPrePTA followed by a significant increase in HR and/or SBP within 5min after the time points (p<0.01). The ΔPTA was associated with the following performance in predicting HDR: AUC ROC [95% CI]=0.80 [0.71 to 0.88] (p<0.05), with a sensitivity of 77% and a specificity of 72% for a threshold value of -18%. Although encouraging, the performance of the PTA index and its dynamic variation needs to be further evaluated, particularly in different clinical contexts.
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performance du Parasympathetic Tone activity pta pour predire la reactivite hemodynamique chez le chien anesthesie
Anesthésie & Réanimation, 2015Co-Authors: Christelle Mansour, Emmanuel Boselli, Bernard Allaouchiche, Jeannemarie Bonnetgarin, Tristan Merlin, Stephane JunotAbstract:Introduction L’Analgesia Nociception Index (ANI) a montre une bonne performance pour predire une reactivite hemodynamique (RH) chez l’homme [1] . Un index similaire variant de 0 a 100, base sur la composante parasympathique de la variabilite de la frequence cardiaque et denomme Parasympathetic Tone Activity (PTA) a ete developpe pour une utilisation chez l’animal. L’objectif de cette etude etait d’evaluer la performance du PTA pour predire une RH peroperatoire chez le chien anesthesie. Materiel et methodes Le PTA a ete evalue sur des chiens en bonne sante (ASA 1–2) anesthesies pour une chirurgie viscerale, orthopedique ou cutanee. Les animaux etaient premediques par morphine 0,2 mg/kg intramusculaire. L’anesthesie etait induite par diazepam 0,2 mg/kg et propofol 4 mg/kg intraveineux suivis par un entretien a l’isoflurane. Les chiens etaient ventiles artificiellement (frequence respiratoire = 15 cycles/min, volume courant = 8 mL/kg) et recevaient une analgesie de secours par fentanyl 1 μg/kg en cas de RH, definie par une augmentation de plus de 20 % de la frequence cardiaque (FC) et/ou de la pression arterielle systolique (PAS) en 5 min. Le PTA a ete mesure pour chaque animal avec le moniteur PhysioDoloris™ (Mdoloris Medical Systems, Lille, France) a des temps definis : T0 (induction), T1 (incision cutanee), T2 (5 min avant RH ou 1 min avant une baisse de PTA ≥ 20 %) et T3 (5 min apres l’arret de l’isoflurane). Les variations normalisees du PTA (ΔPTA) ont egalement ete calculees : ΔPTA = [(PTA1min–PTAi)/(PTAi + PTA1 min)/2], ou PTAi est la valeur de PTA au temps predefini et PTA1 min est la valeur de PTA 1 min apres le temps predefini. L’analyse statistique a consiste en des tests de Friedman pour mesures repetees et test a posteriori de Tukey pour comparer le ΔPTA chez les chiens presentant ou ne presentant pas de RH aux temps T0, T1, T2 et T3. La performance du ΔPTA pour predire une RH a egalement ete evaluee par courbe ROC avec les donnees groupees des temps T0 a T3. Une valeur de p Resultats Vingt chiens ont ete incorpores dans l’etude. L’indice PTA diminuait significativement apres 1 min pour les temps T1 (p Fig. 1 ), avec une sensibilite de 75 % et une specificite de 74 % pour une valeur de –19 % ( Tableau 1 ). Discussion Dans un contexte veterinaire clinique et avec un protocole anesthesique standardise, le PTA a permis de predire une RH apres stimulation nociceptive peroperatoire. Cet index pourrait ainsi permettre d’optimiser l’administration d’analgesique sous anesthesie generale chez le chien. Il necessite cependant d’etre evalue dans des contextes cliniques et protocoles anesthesiques varies afin de confirmer ces resultats.
