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Fabus MS, Sleigh JW, Warnaby CE. Effect of Propofol on Heart Rate and Its Coupling to Cortical Slow Waves in Humans. Anesthesiology 2024; 140:62-72. [PMID: 37801625 PMCID: PMC7615371 DOI: 10.1097/aln.0000000000004795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/08/2023]
Abstract
BACKGROUND Propofol causes significant cardiovascular depression and a slowing of neurophysiological activity. However, literature on its effect on the heart rate remains mixed, and it is not known whether cortical slow waves are related to cardiac activity in propofol anesthesia. METHODS The authors performed a secondary analysis of electrocardiographic and electroencephalographic data collected as part of a previously published study where n = 16 healthy volunteers underwent a slow infusion of propofol up to an estimated effect-site concentration of 4 µg/ml. Heart rate, heart rate variability, and individual slow electroencephalographic waves were extracted for each subject. Timing between slow-wave start and the preceding R-wave was tested against a uniform random surrogate. Heart rate data were further examined as a post hoc analysis in n = 96 members of an American Society of Anesthesiologists Physical Status II/III older clinical population collected as part of the AlphaMax trial. RESULTS The slow propofol infusion increased the heart rate in a dose-dependent manner (mean ± SD, increase of +4.2 ± 1.5 beats/min/[μg ml-1]; P < 0.001). The effect was smaller but still significant in the older clinical population. In healthy volunteers, propofol decreased the electrocardiogram R-wave amplitude (median [25th to 75th percentile], decrease of -83 [-245 to -28] μV; P < 0.001). Heart rate variability showed a loss of high-frequency parasympathetic activity. Individual cortical slow waves were coupled to the heartbeat. Heartbeat incidence peaked about 450 ms before slow-wave onset, and mean slow-wave frequency correlated with mean heart rate. CONCLUSIONS The authors observed a robust increase in heart rate with increasing propofol concentrations in healthy volunteers and patients. This was likely due to decreased parasympathetic cardioinhibition. Similar to non-rapid eye movement sleep, cortical slow waves are coupled to the cardiac rhythm, perhaps due to a common brainstem generator. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Marco S. Fabus
- Wellcome Centre for Integrative Neuroimaging, FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | - Jamie W. Sleigh
- Department of Anaesthesiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Catherine E. Warnaby
- Wellcome Centre for Integrative Neuroimaging, FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
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Ingrande J, Patel HH, Kendall D, Stefanska B, Alexander S, Bakhle M, Cirino G, Docherty JR, George CH, Insel PA, Ji Y, King BF, Lilley E, Panettieri RA, Ramage AG, Sobey CG, Stanford SC, Stephens G, Teixeira M, Vergnolle N, Ahluwalia A. Guidance for the use and reporting of anaesthetic agents in BJP manuscripts involving work with animals. Br J Pharmacol 2023; 180:255-263. [PMID: 36529953 DOI: 10.1111/bph.15992] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Scientists who plan to publish in the British Journal of Pharmacology (BJP) should read this article before undertaking studies utilising anaesthetics in mammalian animals. This editorial identifies certain gaps in the reporting of details on the use of anaesthetics in animal research studies published in the BJP. The editorial also provides guidance, based upon current best practices, for performing in vivo experiments that require anaesthesia. In addition, mechanisms of action and physiological impact of specific anaesthetic agents are discussed. Our goal is to identify best practices and to provide guidance on the information required for manuscripts submitted to the BJP that involve the use of anaesthetic agents in studies with experimental animals.
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Affiliation(s)
- Jerry Ingrande
- VA San Diego Healthcare System and University of California, San Diego, California, USA
| | - Hemal H Patel
- VA San Diego Healthcare System and University of California, San Diego, California, USA
| | | | | | | | | | | | | | | | - Paul A Insel
- University of California, San Diego, California, USA
| | - Yong Ji
- Nanjing Medical University, Nanjing, China
| | | | | | | | | | | | | | | | - Mauro Teixeira
- Federal University of Minas Gerais, Belo Horizonte, Brazil
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Cattai A, Rabozzi R, Ferasin H, Isola M, Franci P. Haemodynamic changes during propofol induction in dogs: new findings and approach of monitoring. BMC Vet Res 2018; 14:282. [PMID: 30208893 PMCID: PMC6134702 DOI: 10.1186/s12917-018-1608-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 08/31/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Propofol is one of the most widely used injectable anaesthetic agents in veterinary practice. Cardiovascular effects related to propofol use in dogs remain less well defined. The main objective of this study was to evaluate the haemodynamic changes during induction of general anaesthesia with propofol in healthy dogs, by a beat-to-beat continuous monitoring. All dogs were premedicated with intramuscular acepromazine (0.015 mg/kg) and methadone (0.15 mg/kg). Transthoracic echocardiography was used to measure the velocity time integral (VTI) of the left ventricular outflow tract. A syringe driver, programmed to deliver propofol 5 mg/kg over 30 s followed by a continuous infusion of 25 mg/kg/h, was used to induce and maintain anaesthesia. From the initiation of propofol administration, heart rate (HR) and mean invasive arterial blood pressure (MAP) were recorded every 5 s for 300 s, while aortic blood flow was continuously recorded and stored for 300 S. maximum cardiovascular depression was defined the lowest MAP (MAP_Tpeak) recorded during the monitored interval. VTI and VTI*HR were calculated at 0, 30, 90, 120, 150 and 300 s post administration of propofol, and at MAP_Tpeak. Haemodynamic effects of propofol in relation to plasma and biophase concentrations were also evaluated by pharmacokinetics simulation. RESULTS The median (range) HR was significantly higher (p = 0.006) at the moment of maximum hemodynamic depression (Tpeak) [105(70-148) bpm] compared with pre-induction values (T0) [65(50-120) bpm]. The median (range) MAP was significantly lower (p < 0.001) at Tpeak [61(51-69) mmHg] compared with T0 [88(72-97) mmHg]. The median (range) VTI and VTI*HR were similar at the two time points [11.9(8.1-17.3) vs 13,3(9,4-16,5) cm, and 1172(806-1554) vs 1002(630-1159) cm*bpm, respectively]. CONCLUSIONS Induction of anaesthesia with propofol causes a drop of arterial pressure in healthy dogs, however cardiac output is well maintained by compensatory chronotropic response. The magnitude of MAP_Tpeak may be strictly related with propofol plasma concentration.
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Affiliation(s)
- Andrea Cattai
- Department of Animal Medicine, Production and Health, Agripolis, Università degli Studi di Padova, Padua, Italy
| | | | - Heidi Ferasin
- Specialist Veterinary Cardiology Consultancy, Lymington Bottom, Four Marks, Hampshire, UK
| | - Maurizio Isola
- Department of Animal Medicine, Production and Health, Agripolis, Università degli Studi di Padova, Padua, Italy
| | - Paolo Franci
- Department of Animal Medicine, Production and Health, Agripolis, Università degli Studi di Padova, Padua, Italy
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Hedenqvist P, Edner A, Jensen-Waern M. Anaesthesia in medetomidine premedicated New Zealand White rabbits: a comparison between intravenous sufentanil-midazolam and isoflurane anaesthesia for orthopaedic surgery. Lab Anim 2014; 48:155-63. [PMID: 24464922 DOI: 10.1177/0023677213516311] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Eighteen female New Zealand White rabbits (3.9 ± 0.4 kg) were anaesthetized with sufentanil-midazolam by intravenous infusion (SUF-MID, n = 9) or isoflurane (ISO, n = 9) for bilateral creation of an osteochondral defect in the medial femur condyle. Subcutaneous premedication with 0.1 mg/kg medetomidine and anaesthesia induction by intravenous infusion of 1.1 µg/kg sufentanil and 0.2 mg/kg midazolam were identical in both groups. During surgery (60 min), the effects on respiratory and circulatory variables serum lactate, total protein and blood glucose were examined. Intermittent positive pressure ventilation (IPPV) was initiated if apnoea lasted>30 s or if end-tidal CO2 ≥8 kPa. The righting reflex was lost in 3 min. IPPV was necessary during most of the anaesthesia for most of the rabbits. Maintenance doses during surgery were 2.0 µg/kg/h sufentanil and 0.4 mg/kg/h midazolam, and 1.4% isoflurane, respectively. Mean arterial blood pressure (MAP) was higher in group SUF-MID than group ISO during surgery (63 ± 12 vs 50 ± 8 mmHg). In group ISO the heart rate was higher during surgery than before anaesthesia (197 ± 26 vs 158 ± 40 bpm) as was blood glucose (9 ± 2 vs 12 ± 3 mmol/L). Serum lactate levels remained unchanged whereas total protein decreased in both groups. Time to recover from anaesthesia did not differ between groups (20 min). Intravenous sufentanil-midazolam infusion provided surgical anaesthesia with a higher MAP than isoflurane anaesthesia. The protocol can be useful in situations in which gas anaesthesia cannot be used or in animals with limited cardiovascular reserves. However, IPPV is necessary.
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Affiliation(s)
- Patricia Hedenqvist
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Yin H, Chen WM, Zhao P. Cerebral state index may reflect electrical brain activity during propofol or isoflurane anaesthesia in rabbits. Vet Rec 2013; 172:184. [PMID: 23292947 DOI: 10.1136/vr.100600] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- H Yin
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang 110004, China
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Hedenqvist P, Edner A, Fahlman Å, Jensen-Waern M. Continuous intravenous anaesthesia with sufentanil and midazolam in medetomidine premedicated New Zealand White rabbits. BMC Vet Res 2013; 9:21. [PMID: 23351150 PMCID: PMC3568725 DOI: 10.1186/1746-6148-9-21] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 01/14/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Anaesthesia in rabbits is associated with a high mortality rate, compared to that in cats and dogs. Total intravenous anaesthesia (TIVA) with drugs that provide cardiovascular stability and are rapidly metabolised could be of benefit for use in rabbits. The aim was to evaluate cardiorespiratory effects of TIVA with sufentanil-midazolam in eight New Zealand White rabbits. Subcutaneous premedication with medetomidine (0.1 mg/kg BW) was followed by IV administration of a mixture of 2.5 μg/mL sufentanil and 0.45 mg/mL midazolam at a rate of 0.3 mL/kg BW/h for anaesthetic induction. Additionally, intravenous boluses of 0.1 mL of the mixture were administered every 20 s until the righting reflex was lost. Following endotracheal intubation, anaesthesia was maintained for 60 min with an infusion rate adjusted to supress the pedal withdrawal reflex. Air and oxygen (1:2) were delivered at 3 L/min. Physiological variables were recorded before induction and at predefined time points during and after anaesthesia. RESULTS Righting and pedal withdrawal reflexes were lost within 3 and 5 min, respectively. Doses of sufentanil and midazolam were 0.48 μg/kg BW and 0.09 mg/kg BW for induction, and 0.72 μg/kg BW/h and 0.13 mg/kg BW/h for maintenance. Apnoea occurred in two rabbits. Induction of anaesthesia caused a significant increase in heart rate, cardiac output and arterial CO2 partial pressure and a decrease in mean arterial pressure, respiratory rate and pH. Mean time from stopping the infusion to endotracheal extubation was 5 min, and to return of the righting reflex 7 min. Anaesthesia was characterized by induction and recovery without excitation, with muscle relaxation, and absence of the pedal withdrawal reflex. CONCLUSIONS TIVA with sufentanil-midazolam provided smooth induction and recovery of anaesthesia in rabbits but with marked hypotension and respiratory depression, requiring mechanical ventilation. Further evaluation is needed to establish if the protocol is useful for rabbits undergoing surgery.
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Affiliation(s)
- Patricia Hedenqvist
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, P.O. Box 7054, SE, 750 07, Uppsala, Sweden
| | - Anna Edner
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, P.O. Box 7054, SE, 750 07, Uppsala, Sweden
| | - Åsa Fahlman
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, P.O. Box 7054, SE, 750 07, Uppsala, Sweden
| | - Marianne Jensen-Waern
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, P.O. Box 7054, SE, 750 07, Uppsala, Sweden
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Durand M. [Anaesthesia and vasomotor tone during CPB: intravenous anaesthetics]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 2012; 31 Suppl 1:S31-S33. [PMID: 22721519 DOI: 10.1016/s0750-7658(12)70052-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Anaesthesia during CBP is frequently provided using intravenous anaesthetic drugs, particularly propofol. The effects of the different drugs have been studied during CPB. These drugs have an arterial and venous vasodilator effect during CPB which is dose dependent and is more pronounced for propofol. High doses of propofol or thiopental reduce cerebral blood flow but provide no additional neurological protection.
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Affiliation(s)
- M Durand
- Unité De Réanimation Cardiovasculaire et Thoracique, Pole Anesthésie Réanimation, Hôpital Albert Michallon, BP 217, 38043 Grenoble cedex 9, France. MDurand@CHU- Grenoble.fr
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Wiese AJ, Lerche P, Cleale RM, Muir WW. Investigation of escalating and large bolus doses of a novel, nano-droplet, aqueous 1% propofol formulation in cats. Vet Anaesth Analg 2010; 37:250-7. [DOI: 10.1111/j.1467-2995.2010.00529.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Leite W, Barrêto Júnior R, Queiroz G, Paula V. Uso do propofol na indução anestésica de cutias (Dasyprocta sp.). ARQ BRAS MED VET ZOO 2008. [DOI: 10.1590/s0102-09352008000400012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Avaliou-se o emprego do propofol, por via intravenosa, como agente indutor anestésico em cutias (Dasyprocta sp), utilizando-se 10 fêmeas adultas, com pesos entre 1,5 a 2,0kg, criadas em cativeiro. Avaliaram-se as freqüências cardíaca e respiratória, a temperatura retal e a pressão arterial sistólica, antes da administração do propofol e logo após a anestesia dos animais. Foram mensurados o período hábil e de recuperação da anestesia. As médias das freqüências cardíaca e respiratória, temperatura retal e a pressão arterial sistólica basais foram de 220bcm, 92mrm, 38,95ºC e 110mmHg, respectivamente. Após a indução, as médias obtidas para essas variáveis foram de 214bcm, 84mrm, 39,05ºC e 80mmHg. As médias dos períodos hábil e de recuperação da anestesia foram de 10min e 45seg e 15min e 40seg, respectivamente. O propofol, quando utilizado em dose única, mostrou-se seguro, não alterando significativamente os parâmetros fisiológicos, podendo ser considerado um fármaco de escolha para a indução anestésica de cutias.
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Baumgartner C, Bollerhey M, Henke J, Wagner S, Ungerer M, Erhardt W. Effects of propofol on ultrasonic indicators of haemodynamic function in rabbits. Vet Anaesth Analg 2008; 35:100-12. [PMID: 17850227 DOI: 10.1111/j.1467-2995.2007.00360.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
OBJECTIVE To evaluate the cardiovascular effects of intravenous propofol in rabbits. STUDY DESIGN Randomized, prospective, experimental study. ANIMALS Thirty-one female New Zealand White rabbits. METHODS Rabbits were allocated to one of two groups [propofol (P) or conscious (C)]. In C (n = 16) vascular dimensions were measured using ultrasound of the left common carotid artery (ACC) and the abdominal aorta (AA). Group P (n = 15) received propofol 4.0-8.0 mg kg(-1) intravenously (IV). Anaesthesia was maintained with propofol at 1.2-1.3 mg kg(-1) minute(-1). Subsequently, three propofol injections (8 mg kg(-1)) were given. Before and for 10 minutes after each injection the following vascular and haemodynamic variables were recorded (a) at the ACC after the first injection; and (b) at the AA after the second injection: vessel diameter [D, (mm)], peak systolic, minimum diastolic, end-diastolic and average blood flow velocities [psBFV, mdBFV, edBFV, Vave (cm second(-1))], average volumetric flow [VFave (mL s(-1))], resistance index (RI) and pulsatility index (PI) mean arterial pressure (MAP), heart rate (HR), arterial oxygen saturation (SpO(2)) and end-tidal CO(2) (Pe'CO(2)). Echocardiography was performed after the third propofol bolus injection to investigate changes in cardiac parameters [fractional shortening, FS (%)]. RESULTS Intravenous propofol injections caused a significant decrease in vessel diameter, volumetric flow and edBFV, and significant increases in psBFV, RI and PI. Baseline levels for vessel diameter and psBFV were restored 6-8 minutes after injection. Propofol injection decreased FS significantly by 7 minutes after injection while MAP and HR were significantly reduced for 4 minutes. CONCLUSION AND CLINICAL RELEVANCE Injections of propofol (8 mg kg(-1)) produced an immediate, transient decrease in vascular diameters, a significant decrease in ventricular performance and an increase in peripheral vascular resistance (ACC and AA). Propofol should probably not be or only carefully used in rabbits with ventricular dysfunction.
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Affiliation(s)
- Christine Baumgartner
- Working Group of Experimental Surgery, Institute for Experimental Oncology and Therapeutic Research, Technical University, Munich, Germany.
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Umehara S, Tanaka M, Nishikawa T. Effects of Sevoflurane Anesthesia on Carotid-Cardiac Baroreflex Responses in Humans. Anesth Analg 2006; 102:38-44. [PMID: 16368802 DOI: 10.1213/01.ane.0000183651.10514.9a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Sevoflurane depresses cardio-vagal baroreflex gain (ability of vagally mediated R-R interval response to arterial blood pressure change). We examined the effects of sevoflurane anesthesia on maximum buffering capacity of vagally mediated hemodynamic control (baroreflex range) by examining the entire stimulus-response baroreflex relation. Electrocardiogram and invasive arterial blood pressure were monitored in 11 healthy volunteers. Carotid-cardiac baroreflex responses were elicited by increasing neck chamber pressure (external pressure applied over the bilateral carotid sinuses) to 40 mm Hg for 5 heartbeats followed by decreasing chamber pressure by successive 15-mm Hg R-wave triggered decrements to -65 mm Hg during held expiration. R-R intervals were plotted as functions of preceding carotid distending pressure. Range, maximum gain, and operational point (relative position of the resting set point within the entire baroreflex response curve) were determined at conscious baseline, during 2% (end-tidal) sevoflurane anesthesia, without and with phenylephrine infusion to maintain conscious arterial blood pressure, and at 30, 60, 120, and 180 min after emergence from anesthesia. Sevoflurane anesthesia significantly depressed maximum gain (from 3.84 +/- 0.99 to 1.04 +/- 0.40 ms/mm Hg [mean +/- sd]; P < 0.001) and range (from 207 +/- 43 to 52 +/- 19 ms; P < 0.001) of the reflex relation, both of which recovered at 120 and 180 min after emergence. Phenylephrine infusion only partially restored these variables. The operational point was unchanged throughout the study. Our results indicate that maximum cardio-vagal compensatory response to buffer hemodynamic perturbation is depressed during sevoflurane anesthesia. Sevoflurane-induced hypotension, which produced vagal withdrawal, did not play an important role in depressing cardio-vagal reflex function.
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Affiliation(s)
- Shino Umehara
- Department of Anesthesia, Akita University School of Medicine, Akita-city, Japan
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Sato M, Tanaka M, Umehara S, Nishikawa T. Baroreflex control of heart rate during and after propofol infusion in humans. Br J Anaesth 2005; 94:577-81. [PMID: 15722386 DOI: 10.1093/bja/aei092] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND This study was designed to determine cardiovagal baroreflex gain during propofol infusion and to characterize its recovery profile using the pharmacological and spontaneous sequence methods in 13 healthy volunteers without cardiovascular or autonomic disorders. METHODS After an 8- to 10-h fast and no premedication, measurements of RR intervals obtained from the electrocardiogram and non-invasive beat-to-beat systolic blood pressure (SP) were made at conscious baseline, at 60 and 120 min after induction of general anaesthesia using propofol, and at 20, 60, 120 and 180 min after emergence from anaesthesia. During propofol anaesthesia, ventilation was mechanically controlled to maintain normocapnia and calculated propofol concentration was adjusted by a TCI system at 5 microg ml(-1). Baroreflex responses were triggered by bolus i.v. injections of phenylephrine and nitroprusside to alter SP by 15-30 mm Hg. The linear portions of the baroreflex curves relating RR intervals and SP by least-square regression analysis were determined to obtain pharmacological gains. In addition, spontaneous sequence baroreflex gains were calculated from spontaneously fluctuating SP and RR intervals. RESULTS Baseline pressor and depressor test gains before propofol anaesthesia were 29.1 (SD 14.9) and 12.5 (7.8) ms mm Hg(-1), respectively. They were significantly depressed by 65-73% during propofol infusions. Similarly, baseline up- and down-sequence baroreflex gains were 33.8 (28.9) and 27.3 (19.8) ms mm Hg(-1), respectively, and were significantly depressed by 71-87% during propofol anaesthesia. Pressor test and up-sequence baroreflex gains returned to the baseline values 20 min after emergence from propofol anaesthesia, but depressor test and down-sequence baroreflex gains did not recover until 60 min after emergence. CONCLUSIONS We conclude that heart rate responses to both lowering and elevating blood pressure were depressed by propofol anaesthesia, and 60 min was required for their full recovery after discontinuation of propofol infusion.
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Affiliation(s)
- M Sato
- Department of Anaesthesia, Akita University School of Medicine, Akita City 010-8543, Japan
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Brookes ZLS, Brown NJ, Reilly CS. Response of the rat cremaster microcirculation to hemorrhage in vivo: differential effects of intravenous anesthetic agents. Shock 2002; 18:542-8. [PMID: 12462563 DOI: 10.1097/00024382-200212000-00010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Anesthetic agents are known to have differential effects on both the systemic circulation and the microcirculation. The aim of this study was to compare the effects of several intravenous (i.v.) agents on the microcirculatory response to hemorrhage. Male Wistar rats (n = 52) were anesthetized i.v. either with propofol and fentanyl (propofol fentanyl), ketamine, or thiopental. Cardiovascular variables were monitored. The cremaster muscle was observed by using fluorescent intravital microscopy. FITC-BSA was administered (0.25 mL/100 g, i.a.) to determine macromolecular leak, an index of vessel integrity. Animals were further allocated into control (C), 10% hemorrhage (H), or hemorrhage re-infusion (H-R, removal of 10% blood volume and then re-infusion of saline and blood) groups. When systolic arterial pressure (SAP) was maintained after hemorrhage, constriction of A3 and A4 arterioles (5-30 microm) was accompanied by no change in the diameter of A1 (80-130 microm): most frequent with ketamine (A1: -1.7 +/- 1.2; A4: -13.9 +/- 2.7%; H and H-R: n = 9/11). With lower SAP, dilation of the A3 and A4 was accompanied by constriction of the A1: most frequent with propofol/fentanyl (A1: -8.0 +/- 2.5; A4; 35.1 +/- 9.4%; H and H-R: n = 6/11). No increases in macromolecular leak occurred with any anesthetic agent or in H or H-R groups. The response of cremaster muscle microcirculation to hemorrhage differs with different i.v. anesthetic agents. Dilation of small arterioles is the predominant response with propofol/fentanyl and constriction of small arterioles with ketamine.
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Affiliation(s)
- Zoë L S Brookes
- Section of Surgical and Anaesthetic Sciences, University of Sheffield, Royal Hallamshire Hospital, Sheffield S10 2JF, United Kingdom
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Akine A, Suzuka H, Hayashida Y, Kato Y. Effects of ketamine and propofol on autonomic cardiovascular function in chronically instrumented rats. Auton Neurosci 2001; 87:201-8. [PMID: 11476280 DOI: 10.1016/s1566-0702(00)00271-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this study C. we systematically examined the effects of ketamine and propofol at various doses (5-20 mg/kg) on blood pressure, heart rate and renal sympathetic nerve activity in chronically instrumented Wistar rats. We also assessed the effects of these anesthetics on the baroreflex control of heart rate and renal sympathetic nerve activity. Ketamine (10 mg/kg) increased blood pressure by 30.0+/-4.5%, heart rate by 17.7-3.3% and renal sympathetic nerve activity by 38.8+/-14.6%, while propofol (10 mg/kg) decreased blood pressure by 18.9+/-3.5%, heart rate by 5.5+/-2.5% and renal sympathetic nerve activity by 7.5+/-2.1%. These variables showed dose-dependent responses to both agents. Both ketamine and propofol decreased the range and maximum gain of the logistic function curve obtained by relating mean blood pressure to heart rate and blood pressure to renal sympathetic nerve activity. In conclusion, ketamine and propofol had different effects on autonomic cardiovascular function, but attenuated the baroreflex sensitivity of heart rate and renal sympathetic nerve activity in a dose-dependent manner. These results suggest the possibility that baroreflex sensitivity may reflect the depth of anethesia.
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Affiliation(s)
- A Akine
- Department of Dental Pharmacology, Nagasaki University School of Dentistry, Japan.
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Keyl C, Schneider A, Dambacher M, Wegenhorst U, Ingenlath M, Gruber M, Bernardi L. Dynamic cardiocirculatory control during propofol anesthesia in mechanically ventilated patients. Anesth Analg 2000; 91:1188-95. [PMID: 11049907 DOI: 10.1097/00000539-200011000-00027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
UNLABELLED We evaluated dynamic cardiovascular control by spectral analytical methods in 20 young adults anesthetized with propofol (2.5 mg/kg, followed by continuous infusion of 0.1 mg/kg/min) and in an awake control group during cyclic stimulation of the carotid baroreceptors via sinusoidal neck suction at 0.2 Hz (baroreflex response mediated mainly by vagal activity) and at 0.1 Hz (baroreflex response mediated by vagal and sympathetic activity). During anesthesia and mechanical ventilation at 0.25 Hz, major underdampened hemodynamic oscillations occurred at 0.055 +/- 0.012 Hz. The response of RR intervals to baroreceptor stimulation at 0.2 Hz was markedly decreased during anesthesia (median of transfer function magnitude between neck suction and RR intervals 3% of the awake control). Blood pressure response to baroreceptor stimulation at 0.1 Hz was significantly decreased during anesthesia to 26% (systolic blood pressure), and 44% (diastolic blood pressure) of the awake control. There was a significant delay in baroreflex effector responses during anesthesia. Our results demonstrate a markedly depressed vagally mediated heart rate response and an impaired blood pressure response to cyclic baroreceptor stimulation during propofol anesthesia in mechanically ventilated patients. The disturbed baroreflex control is accompanied by an irregular dynamic behavior of cardiovascular regulation, indicating a decreased stability of the control system. IMPLICATIONS An irregular dynamic behavior of the cardiovascular control system, associated with an impaired baroreflex control of heart rate and blood pressure, can be observed during propofol anesthesia in mechanically ventilated subjects.
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Affiliation(s)
- C Keyl
- Department of Anesthesiology, University Medical Center, University of Regensburg, Germany.
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Keyl C, Schneider A, Dambacher M, Wegenhorst U, Ingenlath M, Gruber M, Bernardi L. Dynamic Cardiocirculatory Control During Propofol Anesthesia in Mechanically Ventilated Patients. Anesth Analg 2000. [DOI: 10.1213/00000539-200011000-00027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Xu H, Aibiki M, Yokono S, Ogli K. Dose-dependent effects of propofol on renal sympathetic nerve activity, blood pressure and heart rate in urethane-anesthetized rabbits. Eur J Pharmacol 2000; 387:79-85. [PMID: 10633164 DOI: 10.1016/s0014-2999(99)00767-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To evaluate the role of the autonomic nervous system in hemodynamic changes after propofol bolus injection, we used direct recordings of renal sympathetic nerve activity to examine the dose-dependent effects of propofol (2.5, 5, 10, and 20 mg/kg) on heart rate, mean blood pressure and renal sympathetic nerve activity in urethane-anesthetized rabbits. The animals were divided into four groups: animals with an intact neuraxis (intact group), cervical vagal nerve-sectioned animals (vagotomy group), carotid sinus and aortic-nerve sectioned animals (SAD group), and animals with SAD plus vagotomy (SADV group). Heart rate did not change significantly even after administration of 2.5 and 5 mg/kg but decreased markedly on 20 mg/kg injection in all groups. The intact and vagotomy groups had augmented renal sympathetic nerve activity with insignificant changes in mean blood pressure after 5 mg/kg injection of the agent. Insignificant changes of renal sympathetic nerve activity but a remarkable decrease of mean blood pressure appeared after 10 mg/kg propofol. Sustained hypotension in parallel with a profound depression of renal sympathetic nerve activity developed at the dose of 20 mg/kg. In SAD and SADV groups, however, dose-dependent depressions of renal sympathetic nerve activity were accompanied by decreases of mean blood pressure. These results suggest the following: (1) propofol-induced hypotensive effects are probably produced by the central-mediated sympathetic depression. (2) The baroreceptor reflex may be preserved at the lower dose of the agent. (3) Heart rate does not change significantly unless a large dose of propofol is used. The difference in effects on heart rate and on mean blood pressure may denote a greater inhibition of sympathetic vascular outflow than of the cardiac sympathetic outflow regulating cardiac rate and contractility. This hypothesis needs further clarification.
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Affiliation(s)
- H Xu
- Department of Anesthesiology and Emergency Medicine, and Intensive Care Unit, Kagawa Medical University, 1750-1, Ikenobe, Miki, Japan
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Matthews NS, Hartsfield SM, Hague B, Carroll GL, Short CE. Detomidine-propofol anesthesia for abdominal surgery in horses. Vet Surg 1999; 28:196-201. [PMID: 10338166 DOI: 10.1053/jvet.1999.0196] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To evaluate propofol for induction and maintenance of anesthesia, after detomidine premedication, in horses undergoing abdominal surgery for creation of an experimental intestinal adhesion model. STUDY DESIGN Prospective study. ANIMALS Twelve horses (424 +/- 81 kg) from 1 to 20 years of age (5 females, 7 males). METHODS Horses were premedicated with detomidine (0.015 mg/kg i.v.) 20 to 25 minutes before induction, and a propofol bolus (2 mg/kg i.v.) was administered for induction. Propofol infusion (0.2 mg/kg/min i.v.) was used to maintain anesthesia. The infusion rate was adjusted to maintain an acceptable anesthetic plane as determined by muscle relaxation, occular signs, response to surgery, and cardiopulmonary responses. Oxygen (15 L/min) was insufflated through an endotracheal tube as necessary to maintain the SpO2 greater than 90%. Systolic (SAP), mean (MAP), and diastolic (DAP) arterial pressures, heart rate (HR), electrocardiogram (ECG), respiratory rate (RR), SpO2 (via pulse oximetry), and nasal temperature were recorded at 15 minute intervals, before premedication and after induction of anesthesia. Arterial blood gas samples were collected at the same times. Objective data are reported as mean (+/-SD); subjective data are reported as medians (range). RESULTS Propofol (2.0 mg/kg i.v.) induced anesthesia (mean bolus time, 85 sec) within 24 sec (+/-22 sec) after the bolus was completed. Induction was good in 10 horses; 2 horses showed signs of excitement and these two inductions were not smooth. Propofol infusion (0.18 mg/kg/min +/- 0.04) was used to maintain anesthesia for 61 +/- 19 minutes with the horses in dorsal recumbency. Mean SAP, DAP, and MAP increased significantly over time from 131 to 148, 89 to 101, and 105 to 121 mm Hg, respectively. Mean HR varied over time from 43 to 45 beats/min, whereas mean RR increased significantly over anesthesia time from 4 to 6 breaths/min. Mean arterial pH decreased from a baseline of 7.41 +/- 0.07 to 7.30 +/- 0.05 at 15 minutes of anesthesia, then increased towards baseline values. Mean PaCO2 values increased during anesthesia, ranging from 47 to 61 mm Hg whereas PaO2 values decreased from baseline (97 +/- 20 mm Hg), ranging from 42 to 57 mm Hg. Muscle relaxation was good and no horses moved during surgery: Recovery was good in 9 horses and acceptable in 3; mean recovery time was 67 +/- 29 minutes with 2.4 +/- 2.4 attempts necessary for the horses to stand. CONCLUSIONS Detomidine-propofol anesthesia in horses in dorsal recumbency was associated with little cardiovascular depression, but hypoxemia and respiratory depression occurred and some excitement was seen on induction. CLINICAL RELEVANCE Detomidine-propofol anesthesia is not recommended for surgical procedures in horses if dorsal recumbency is necessary and supplemental oxygen is not available (eg, field anesthesia).
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Affiliation(s)
- N S Matthews
- Texas Veterinary Medical Center, Texas A & M University, College Station 77843-4474, USA
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Ikeno S, Akazawa S, Shimizu R, Nakaigawa Y, Ishii R, Inoue S, Satoh M. Propofol does not affect the canine cardiac conduction system under autonomic blockade. Can J Anaesth 1999; 46:148-53. [PMID: 10083995 DOI: 10.1007/bf03012549] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
PURPOSE To determine the effects of propofol on the cardiac conduction system in dogs with pharmacological autonomic blockade. METHODS In eight mongrel dogs receiving 6 mg.kg-1.hr-1 propofol and vecuronium under pharmacological autonomic blockade with atropine and propranolol the infusion rates of propofol were increased from 6, (baseline), to 12, 18 and 24 mg.kg-1.hr-1 at 60-min intervals. An electrophysiological study assessed sinus rate, sinus node recovery time, corrected sinus node recovery time, intraatrial conduction time, AV nodal effective refractory period, Wenckebach cycle length and AV conduction times. Electrocardiographical variables and arterial pressures were also measured. All measurements were repeated at 30 min after the beginning of each infusion of propofol. RESULTS Propofol did not produce direct effects on the electrophysiological or electrocardiographical variables at any infusion rates. Heart rates did not change at higher infusion rates in the presence of decreases in arterial pressures. CONCLUSION Propofol did not affect the cardiac conduction system in the presence of autonomic blockade. Thus, the direct cardiac effects of propofol do not play a causative role in the genesis of propofol-associated bradyarrhythmias.
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Affiliation(s)
- S Ikeno
- Department of Anaesthesiology, Jichi Medical School, Tochigi, Japan.
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Hartikainen K, Rorarius M, Mäkelä K, Yli-Hankala A, Jäntti V. Propofol and isoflurane induced EEG burst suppression patterns in rabbits. Acta Anaesthesiol Scand 1995; 39:814-8. [PMID: 7484040 DOI: 10.1111/j.1399-6576.1995.tb04176.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The aim of this study was to compare propofol produced EEG burst suppression with isoflurane produced burst suppression in rabbits and to see whether rabbits can serve as models in studying the effects of different anaesthetics on human EEG. We recorded EEG of eight rabbits anaesthetised with isoflurane and propofol. The isoflurane bursts had higher amplitude than propofol bursts (P < 0.005). Isoflurane bursts appeared on distinct DC-shifts while propofol bursts were on slow waves. The EEG patterns were, however, different from those seen in humans. Rabbits did not have the rhythms seen in humans. We conclude that rabbits can be used to study the EEG effects of anaesthetics, such as the timing properties and reactivity of burst suppression pattern. However, this model seems less promising in the study of rhythmic activity seen in human EEG during burst suppression.
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Affiliation(s)
- K Hartikainen
- Department of Biomedical Sciences, University of Tampere, Finland
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Krassioukov AV, Gelb AW, Weaver LC. Action of propofol on central sympathetic mechanisms controlling blood pressure. Can J Anaesth 1993; 40:761-9. [PMID: 8403160 DOI: 10.1007/bf03009773] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
This study was done using Wistar rats to determine if the actions of propofol (22 +/- 1, 40 +/- 2, 64 +/- 3 and 103 +/- 3 mg.kg-1 x hr-1) decreased blood pressure and heart rate through depression of brain stem vasomotor centres. All rats were given atropine to block vagal influences on the heart. Propofol decreased renal nerve activity as well as blood pressure and heart rate in a dose-dependent manner. Infusion of the lowest dose of propofol (22 +/- 1 mg.kg-1 x hr-1) had no effect on blood pressure, heart rate and renal nerve activity. Infusion of propofol at 40 +/- 2 mg.kg-1 x hr-1 decreased renal activity by 22 +/- 4% (mean +/- SEM) and at 64 +/- 3 mg.kg-1 x hr-1 it decreased renal nerve activity by 36 +/- 6%. Finally, infusion of the largest dose of propofol (102 +/- 3 mg.kg-1 x hr-1) decreased nerve activity by 50 +/- 5%. The haemodynamic changes observed in our experiments during the infusion propofol paralleled the changes in sympathetic firing, suggesting that hypotension was caused by central actions of propofol to depress sympathetic firing. In experiments with bolus injections of propofol, the renal nerve activity returned to normal before arterial pressure and heart rate recovered. Because decreases in blood pressure and heart rate were longer-lasting than changes in renal nerve activity, a part of the vasodepression and bradycardia caused by propofol likely resulted from direct actions on blood vessels and the heart. Sympathetic and cardiovascular responses to blocking neurons in the ventrolateral medulla with microinjection of glycine were depressed by propofol.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A V Krassioukov
- Department of Stroke and Aging, John P. Robarts Research Institute, University of Western Ontario
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Abstract
Propofol is an intravenous anaesthetic which is chemically unrelated to other iv anaesthetics. Most anaesthetists are now becoming familiar with propofol's pharmacokinetic and pharmacodynamic properties. It has proved to be a reliable drug that can be used safely for induction and maintenance of anaesthesia for most surgical procedures and unlike other anaesthetic agents, it can especially be extended into the postoperative setting or intensive care unit for sedation. Propofol's greatest attributes are its pharmacokinetic properties which result in a rapid, clear emergence and lack of cumulative effects even after prolonged administration. Compared with other iv anaesthetics, the induction dose of propofol has a relatively higher incidence of respiratory depression, short-lived apnoea and blood pressure reduction that may occasionally be marked. Possible mechanisms for the hypotension may relate to (1) its action on peripheral vasculature (vasodilatation), (2) decreased myocardial contractility, (3) resetting of the baroreflex activity and (4) inhibition of the sympathetic nervous system outflow. In vitro studies indicate that propofol depresses the immunological reaction to bacterial challenge as well as the chemotactic activity. Clinical studies, in cardiac surgery, have demonstrated that propofol, in association with an opioid, is a logical anaesthetic choice. Propofol is about to receive approval for continuous iv sedation. Comparative studies of propofol and midazolam have clearly demonstrated the superiority of propofol in terms of rapid recovery and precise control of the level of sedation.
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Affiliation(s)
- N R Searle
- Department of Anaesthesia, Montreal Heart Institute, Quebec, Canada
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Kamijo Y, Goto H, Nakazawa K, Benson KT, Arakawa K. Arterial baroreflex attenuation during and after continuous propofol infusion. Can J Anaesth 1992; 39:987-91. [PMID: 1451228 DOI: 10.1007/bf03008351] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The reduction of arterial blood pressure produced by propofol may be, in part, attributable to impaired baroreflex integrity. The purpose of this study was to investigate arterial baroreflex sensitivity during and after continuous propofol infusion. In urethane anaesthetized rabbits, left renal sympathetic nerves were exposed and placed on a bipolar silver electrode to record renal sympathetic nerve activity (RSNA). Mean arterial pressure (MAP) via a femoral artery and heart rate (HR) by electrocardiogram were continuously recorded. The rabbits were divided into two groups of eight each: Group 1, propofol 5 mg.kg-1 bolus followed by infusion 0.5 mg.kg-1 x min-1; Group 2, propofol 2 mg.kg-1 bolus followed by 0.2 mg.kg-1 x min-1. Phenylephrine pressor and sodium nitroprusside (SNP) depressor tests were carried out before propofol was started (control), at 15 and 30 min during 30 min infusion, and at 15, 30 and 60 min after its discontinuation. The change of RSNA was plotted with respect to every 5 mmHg increment and decrement of MAP to construct sympathetic baroreflex sigmoid curves, and to evaluate baroreflex sensitivity. The baroreflex sensitivity was also evaluated by calculating the ratio of maximum increase of RSNA or HR to SNP-induced maximum decrease of MAP (delta RSNA/delta MAP, delta HR/delta MAP). Despite the same decreases or increases in MAP, RSNA was attenuated after 15 and 30 min of propofol infusion in both groups compared with control (P < 0.05). Decreased delta RSNA/delta MAP gradually returned to the control level 60 min after discontinuation of propofol in Group 1.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- Y Kamijo
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City 66160-7415
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Sellgren J, Biber B, Henriksson BA, Martner J, Pontén J. The effects of propofol, methohexitone and isoflurane on the baroreceptor reflex in the cat. Acta Anaesthesiol Scand 1992; 36:784-90. [PMID: 1466215 DOI: 10.1111/j.1399-6576.1992.tb03565.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The effects of propofol (P), methohexitone (M) and isoflurane (I) on the baroreceptor reflex were studied in a cat model in which the blood pressure in a bilateral isolated carotid sinus preparation was artificially varied between 50-200 mmHg. The influence from aortic and cardiopulmonary baroreceptors was excluded by vagotomy. With basal chloralose anaesthesia as control, the investigated anaesthetics were used in doses corresponding to MAC 0.5 and 1.0. The maximum change in systemic mean arterial pressure (MAP) and heart rate (HR) following a defined increase in carotid sinus pressure was used as an index of baroreceptor reflex sensitivity. Compared to control, M and I anaesthesia were associated with significant depression of baroreceptor reflex sensitivity at the high dose (corresponding to MAC 1.0), and during I anaesthesia also at the low dose (MAC 0.5). The baroreceptor reflex sensitivity was maintained during propofol anaesthesia. The carotid sinus pressure interval at which the maximum changes in MAP could be elicited, was significantly higher during M than during P. This indicates resetting of the baroreflex.
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Affiliation(s)
- J Sellgren
- Department of Anaesthesiology and Intensive Care, University of Gothenburg, Sweden
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25
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Bricchi M, Gemma M. [Asystole during anesthesia with propofol]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 1991; 10:492. [PMID: 1755563 DOI: 10.1016/s0750-7658(05)80858-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Van Leeuwen AF, Evans RG, Ludbrook J. Effects of halothane, ketamine, propofol and alfentanil anaesthesia on circulatory control in rabbits. Clin Exp Pharmacol Physiol 1990; 17:781-98. [PMID: 2078906 DOI: 10.1111/j.1440-1681.1990.tb01280.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
1. We have made a within-rabbit comparison of the effects of four general anaesthetic regimens on the haemodynamic response to acute reduction in central blood volume and on baroreflex control of heart rate. 2. Acute haemorrhage was simulated by gradually inflating a cuff on the inferior vena cava in order to cause cardiac output to fall at a constant rate of 8.5%/min while the responses of systemic vascular resistance, arterial pressure and heart rate were measured. The full range of the baroreceptor-heart rate reflex was elicited by inflating aortic and vena caval cuffs. These indices of circulatory control were repeatedly measured within five protocols, to which each rabbit was exposed in randomized order. 3. In each protocol the rabbit was first studied unanaesthetized. Then a small dose of thiopentone sodium was given (16 mg/kg). In the four main protocols the rabbit was then intubated and ventilated, first with 100% oxygen and then with 50% nitrous oxide, during administration of one of four anaesthetic agents. These were halothane (2.0 and 2.5%), ketamine (2.5 mg/kg per min), propofol (0.83 and 1.25 mg/kg per min) and alfentanil (2.5 and 3.33 micrograms/kg per min). In a sham protocol the effects of 100% oxygen, then those of 50 and 75% nitrous oxide, were studied while the rabbit remained conscious. 4. In unanaesthetized rabbits, in the presence or absence of nitrous oxide, the normal biphasic haemodynamic response to simulated haemorrhage occurred. The first, vasoconstrictor, phase was attenuated by halothane, ketamine and propofol, so that arterial pressure fell more steeply than normal. Not only was the vasoconstrictor phase unaffected by alfentanil but it was extended, so that arterial pressure remained at a normal level even when cardiac output had fallen by 59%. This effect of alfentanil appeared to be mediated centrally, since it could be reproduced by injecting small doses (1.5-7.5 micrograms) into the fourth ventricle. All four anaesthetic agents and nitrous oxide attenuated the baroreceptor control of heart rate. The effect was least with nitrous oxide and alfentanil, greatest with halothane.
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Affiliation(s)
- A F Van Leeuwen
- Department of Surgery, University of Melbourne, Parkville, Victoria, Australia
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Van Leeuwen AF, Evans RG, Ludbrook J. Haemodynamic responses to acute blood loss: new roles for the heart, brain and endogenous opioids. Anaesth Intensive Care 1989; 17:312-9. [PMID: 2570536 DOI: 10.1177/0310057x8901700312] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Information has come forward recently from several sources which provides new insights into the mechanisms that underlie the haemodynamic responses to acute blood loss. In unanaesthetised animals and human volunteers there are two distinct phases to these responses. At first, the engagement of baroreflexes results in a progressive rise in sympathetic vasoconstrictor drive and peripheral resistance, and the maintenance of arterial blood pressure at a near-normal level. When about one-third of blood volume has been lost, reflex sympathetic drive is switched off, and peripheral resistance and blood pressure fall abruptly to low levels despite a burst of vasopressin release. Research in conscious animals has now shown that the onset of this decompensatory phase is triggered by a signal from the heart, which activates an endogenous opioid mechanism in the brain. Activation of this mechanism can be prevented by administering a selective delta-receptor antagonist, or selective mu-receptor agonists (including alfentanil). It has not yet been established that this endogenous opioid mechanism is responsible for the decompensatory phase of acute blood loss in man, nor that it can be prevented or reversed by selective opioid agonists or antagonists.
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Affiliation(s)
- A F Van Leeuwen
- University of Melbourne Department of Surgery, Royal Melbourne Hospital, Victoria, Australia
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Thirion B, Haberer JP. [Circulatory arrest during anesthesia with propofol]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 1989; 8:386-7. [PMID: 2817554 DOI: 10.1016/s0750-7658(89)80090-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Abstract
A review of the pharmacology of propofol, a new IV anesthetic agent, is presented. Solubilized in a soybean emulsion, propofol is one of a series of sterically hindered phenols that exhibit anesthetic activity. Induction of anesthesia with propofol may be associated with pain on injection, apnea, and a reduction in arterial blood pressure (BP) and cardiac output. Caution should be ascribed to its use in patients with coronary artery disease, where these effects may have the potential for producing myocardial ischemia. The hemodynamic responses to laryngoscopy and intubation are attenuated. The pharmacokinetic profile suggests suitability as an infusion for either maintenance of anesthesia or sedation. Use of propofol as an infusion during surgery may result in a further reduction in cardiac output, particularly with the concomitant administration of adjuvant increments of fentanyl. The ventilatory response to CO2 is depressed during such an infusion. The high clearance of propofol suggests that even after a prolonged infusion, recovery should be rapid. This finding has been confirmed in a series of studies establishing propofol as an ideal agent for use in a total IV anesthetic technique. Both the quality and speed of recovery, together with the absence of emetic sequelae, support the use of propofol in an outpatient setting. Propofol appears to have no long-term effect on adrenocortical function and appears safe for use in patients with acute intermittent porphyria and susceptibility to malignant hyperpyrexia.
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Affiliation(s)
- M A Skues
- Sir Humphry Davy Department of Anaesthesia, Bristol Royal Infirmary, University of Bristol, United Kingdom
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