Dexmedetomidine for balanced anaesthesia in horses

258 Pages·2013·1.82 MB·English

Dexmedetomidine for balanced anaesthesia
in horses

Miguel Gozalo Marcilla

Dissertation submitted in fulfilment of the requirements for the degree of Doctor of
Philosophy (PhD) in Veterinary Sciences

May 2013

Promotors:
Dr. Stijn Schauvliege
Prof. dr. Frank Gasthuys

Department of Surgery and Anaesthesia of Domestic Animals
Faculty of Veterinary Medicine
Ghent University
Dexmedetomidine for balanced anaesthesia in horses

Miguel Gozalo Marcilla

Vakgroep Heelkunde en Anesthesie van de Huisdieren

Faculteit Diergeneeskunde

Universiteit Gent

ISBN: 978-90-5864-348-3

Cover design: Ryhove Grafimedia, Gent
“Choose a job you love, and you will never have to work a day in
your life”.

Confucius (551-479 B.C.)

Table of contents

List of abbreviations 7

GENERAL INTRODUCTION 9

Section 1.- Intravenous drugs used in combination with inhalation anaesthesia 21
1.1.- Lidocaine 24
1.2.- Ketamine 30
1.3.- Opioids 34
1.4.- Alpha -adrenoceptor agonists 40
2

Section 2.- The use of dexmedetomidine for balanced anaesthesia in horses 67
2.1.- History of dexmedetomidine 70
2.2.- Mechanism of action of dexmedetomidine 70
2.3.- Pharmacokinetics of dexmedetomidine 72
2.4.- Clinical effects of dexmedetomidine 73
2.4.1.- Sedation and analgesia 73
2.4.2.- Anaesthetic sparing effects 75
2.4.3.- Cardiorespiratory effects 76
2.4.4.- Organ protective effects 77
2.4.5.- Other effects 79
2.5.- Dexmedetomidine in horses 79

SCIENTIFIC AIMS 91

EXPERIMENTAL & CLINICAL STUDIES

Chapter 1.- Cardiopulmonary effects of two constant rate infusions of 97
dexmedetomidine in isoflurane anaesthetized ponies

5
Chapter 2.- Influence of a constant rate infusion of dexmedetomidine 119
on cardiopulmonary function and recovery in isoflurane
anaesthetized horses

Chapter 3.- Effects of a constant rate infusion of dexmedetomidine 141
on the minimum alveolar concentration of sevoflurane in ponies

Chapter 4.- Influence of dexmedetomidine on the minimum end-tidal 161
sevoflurane concentration necessary to prevent movement during
a constant rate infusion of morphine in ponies

Chapter 5.- Comparison of the influence of two different constant rate 179
infusions (dexmedetomidine versus morphine) on anaesthetic
requirements, cardiopulmonary function and recovery quality
in isoflurane anaesthetized horses

GENERAL DISCUSSION 207

SUMMARY 227

SAMENVATTING 233

CURRICULUM VITAE 239

BIBLIOGRAPHY 243

ACKNOWLEDGEMENTS 249

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List of abbreviations

ABP Arterial blood pressure
ANOVA Analysis of variance
ASA American Society of Anesthesiologists
CaO Arterial oxygen content
2
CC Constant current
CEPEF Confidential Enquiry into Perioperative Equine Fatalities
CI Cardiac indexed to weight
CNS Central nervous system
CRI Constant rate infusion
CvO Venous oxygen content
2
CYP450 Cytochrome 450
DAP Diastolic arterial pressure
DO Oxygen delivery
2
DO I Oxygen delivery indexed to weight
2
ECG Electrocardiogram
F ´ Expired fraction
E
FiO Inspired oxygen fraction
2
GABA Gamma-aminobutyric acid
HALO Halothane
Hb Haemoglobin
HR Heart rate
ICU Intensive care unit
IM Intramuscular
IPPV Intermitent positive pressure ventilation
IV Intravenous
ISO Isoflurane
LC Locus coeruleus
LiDCO Lithium dilution cardiac output
MAC Minimum alveolar concentration
MAC Minimum alveolar concentration no movement
NM
MAP Mean arterial pressure
7
NMDA N-methyl-D-aspartate
PaCO Arterial partial pressure of carbon dioxide
2
PaO Arterial partial pressure of oxygen
2
P Barometric pressure
B
PCV Packed cell volume
PEEP Positive end-expiratory pressure
PIVA Partial intravenous anaesthesia
POI Post-operative ileus
Cardiac output
RAP Right atrial pressure
RR Respiratory rate
SAP Systolic arterial pressure
SD Standard deviation
SEVO Sevoflurane
SV Stroke volume
SVI Stroke volume indexed to weight
SVR Systemic vascular resistance
SVRI Systemic vascular resistance indexed to weight
TCI Target-controlled infusions
TIVA Total intravenous anaesthesia
t Terminal half-life
1/2
Ventilation/perfusion
V Steady state volume of distribution
ss

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General introduction

General introduction

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