Quality Of Anaesthetic Induction Research Articles

Comparison of different scales for the evaluation of anxiety and compliance with anesthetic induction in children undergoing scheduled major outpatient surgery

IntroductionAnxiety in children triggered by a scheduled surgical intervention is a major issue due to its frequency and consequences. Preoperative anxiety is associated with increased patient fear and agitation on anesthetic induction. The aim of this study is to compare three preoperative anxiety scales for children undergoing elective outpatient surgery, and to correlate each of these tools with the degree of patient compliance on induction, as assessed by the Induction Compliance Checklist (ICC).MethodsAn observational prospective study was performed on a cohort of children with ages between 2 and 16 years old, scheduled for outpatient surgery. Anxiety was assessed upon arrival to the hospital (M0), during transfer to the surgical unit (M1), and in the operating room during anesthetic induction (M2). Anxiety in the parents (measured with the State-Trait Anxiety Inventory, STAI) and in the children (measured with the Spence Anxiety Scale-Pediatric, SCAS-P, the State-Trait Anxiety Inventory Children, STAIC, and Modified Yale Preoperative Anxiety Scale, m-YPAS) was assessed. Compliance with anesthetic induction was assessed with ICC.ResultsThe study included 76 patients (72.4% male, median age 7.9 years). Anxiety scores (m-YPAS) increased as the moment of surgery approached, being greater at the entrance to the surgical unit (M0 = 26.1 ± 9.5; M1 = 31.8 ± 18.1; M2 = 33.5 ± 21.1). A strong correlation was found between ICC scale and m-YPAS at M1 (0.738) and M2 timepoints (0.794), but not with the rest of scales at M0.ConclusionsStandard anxiety assessment scales do not predict the quality of anesthetic induction. m-YPAS scale can detect increasing anxiety in children as they approach the surgical procedure and this correlates strongly with a worse anesthetic induction, defined by higher score on ICC scale.

Dose requirement and cardiopulmonary effects of diluted and undiluted propofol for induction of anaesthesia in dogs

ObjectiveTo compare the dose, cardiopulmonary effects and quality of anaesthetic induction in dogs using propofol (10 mg mL–1) and diluted propofol (5 mg mL–1). Study designRandomized, blinded, clinical study. AnimalsA total of 28 client-owned dogs (12 males/16 females). MethodsFollowing intramuscular acepromazine (0.02 mg kg–1) and methadone (0.2 mg kg–1), propofol (UP, 10 mg mL–1) or diluted propofol (DP, 5 mg mL–1) was administered intravenously (0.2 mL kg–1 minute–1) by an anaesthetist unaware of the allocated group to achieve tracheal intubation. Sedation, intubation and induction quality were scored from 0 to 3. Pre- and post-induction pulse rate (PR), respiratory rate (fR) and systolic (SAP), mean (MAP) and diastolic (DAP) arterial blood pressure were compared. Time to first breath and induction dose were recorded. Data were analysed for normality and Mann–Whitney U or Student t tests were performed where appropriate. Significance was set at p < 0.05. Data are presented as mean ± standard deviation or median (range). ResultsThe propofol dose administered to achieve induction was lower in the DP group (2.62 ± 0.48 mg kg–1) than in the UP group (3.48 ± 1.17 mg kg–1) (p = 0.021). No difference was observed in pre- and post-induction PR, SAP, MAP, DAP and fR between groups. The differences between post-induction and pre-induction values of these variables were also similar between groups. Time to first breath did not differ between groups. Sedation scores were similar between groups. Quality of tracheal intubation was marginally better with UP 0 (0–1) than with DP 1 (0–2) (p = 0.036), but overall quality of induction was similar between groups [UP 0 (0–1) and DP 0 (0–1), p = 0.549]. Conclusion and clinical relevanceDiluting propofol reduced the dose to induce anaesthesia without significantly altering the cardiopulmonary variables.

Evaluation of the use of midazolam as a co-induction agent with ketamine for anaesthesia in sedated ponies undergoing field castration.

There are limited investigations comparing ketamine to a ketamine-midazolam co-induction. To compare quality and safety of general anaesthesia induced using ketamine alone with anaesthesia co-induced using ketamine and midazolam. Randomised, double blinded, placebo controlled trial. After i.v. detomidine (20 μg/kg) thirty-eight ponies undergoing field castration received either 0.06 mg/kg (0.6 mL/50 kg) midazolam (group M) or 0.6 mL/50 kg placebo (group P) with 2.2 mg/kg ketamine i.v. for anaesthetic induction. Quality of anaesthetic induction, endotracheal intubation, surgical relaxation and recovery were scored using combinations of simple descriptive and visual analogue scales. Time of sedation, induction, start of endotracheal intubation, first movement, sternal recumbency and standing were recorded, as were time, number and total quantity of additional i.v. detomidine and ketamine injections. Cardiorespiratory variables were assessed every 5 min. Adverse effects were documented. Data were tested for normality and analysed with a mixed model ANOVA, Fisher's exact test, unpaired Students' t test and Wilcoxon Rank-sum as appropriate; P<0.05 was considered significant. Group M had better scores for induction (P = 0.005), intubation (P<0.001) and surgical relaxation (P<0.001) and required fewer additional injections of detomidine and ketamine (P = 0.04). Time (minutes) from induction to first movement (P<0.001), sternal recumbency (P =< 0.001) and standing was longer (P = 0.05) in group M. Recoveries were uneventful with no difference in quality between groups (P = 0.78). Clinical study with noninvasive monitoring undertaken in field conditions. Ketamine-midazolam co-induction compared to ketamine alone improved quality of induction, ease of intubation and muscle relaxation without impacting recovery quality.

Effects of intramuscular dexmedetomidine in combination with ketamine or alfaxalone in swine

ObjectiveTo evaluate and compare the use of intramuscular (IM) premedication with dexmedetomidine in combination with ketamine or alfaxalone in pigs. Study designProspective, randomized, ‘blinded’ trial. AnimalsFourteen healthy 2-month-old Landrace × Large White pigs weighing 21.5 ± 0.6 kg. MethodsAnimals were distributed randomly into two groups: group KD (n = 7) was given 10 mg kg−1 IM ketamine + 10 μg kg−1 IM dexmedetomidine; and group AD (n = 7) was given 5 mg kg−1 IM alfaxalone + 10 μg kg−1 IM dexmedetomidine mixed in the same syringe. Pain on injection, degree of sedation and quality of induction were scored. The time from induction of anaesthesia to recumbency was recorded. Once pigs were recumbent, reflexes were evaluated. Pulse and respiratory rates, end-tidal carbon dioxide and arterial oxygen saturation were recorded at 5 and 10 minutes after drug administration. Data were compared using a two-way anova or a t-test for unpaired data as relevant. Data are presented as the mean ± standard deviation (range). ResultsTwo animals in both groups showed slight pain on drug injection. The time to lateral recumbency in group KD [187 ± 34 seconds (153-230)] was similar to group AD [206 ± 36 seconds (150-248)]. In group AD, sedation was deeper, and the quality of anaesthetic induction was smoother. When moved for anaesthesia, five pigs in group KD vocalized. There were no differences between groups in pulse rates, arterial oxygen saturation and end-tidal carbon dioxide; however, the respiratory rate at 10 minutes was significantly higher in group KD than in group AD. Conclusions and clinical relevanceIM dexmedetomidine in combination with ketamine in pigs induced moderate to deep sedation and fair to smooth induction of anaesthesia. When dexmedetomidine was combined with alfaxalone, sedation was deeper, and induction was of a better quality.

The pharmacological effects of the anesthetic alfaxalone after intramuscular administration to dogs.

The pharmacological effects of the anesthetic alfaxalone were evaluated after intramuscular (IM) administration to 6 healthy beagle dogs. The dogs received three IM doses each of alfaxalone at increasing dose rates of 5 mg/kg (IM5), 7.5 mg/kg (IM7.5) and 10 mg/kg (IM10) every other day. Anesthetic effect was subjectively evaluated by using an ordinal scoring system to determine the degree of neuro-depression and the quality of anesthetic induction and recovery from anesthesia. Cardiorespiratory variables were measured using noninvasive methods. Alfaxalone administered IM produced dose-dependent neuro-depression and lateral recumbency (i.e., 36 ± 28 min, 87 ± 26 min and 115 ± 29 min after the IM5, IM7.5 and IM10 treatments, respectively). The endotracheal tube was tolerated in all dogs for 46 ± 20 and 58 ± 21 min after the IM7.5 and IM10 treatments, respectively. It was not possible to place endotracheal tubes in 5 of the 6 dogs after the IM5 treatment. Most cardiorespiratory variables remained within clinically acceptable ranges, but hypoxemia was observed by pulse oximetry for 5 to 10 min in 2 dogs receiving the IM10 treatment. Dose-dependent decreases in rectal temperature, respiratory rate and arterial blood pressure also occurred. The quality of recovery was considered satisfactory in all dogs receiving each treatment; all the dog exhibited transient muscular tremors and staggering gait. In conclusion, IM alfaxalone produced a dose-dependent anesthetic effect with relatively mild cardiorespiratory depression in dogs. However, hypoxemia may occur at higher IM doses of alfaxalone.

The effects of midazolam and butorphanol, administered alone or combined, on the dose and quality of anaesthetic induction with alfaxalone in goats.

Goats are rarely anaesthetised; consequently, scant information is available on the efficacy of anaesthetic drugs in this species. Alfaxalone is a relatively new anaesthetic agent, of which the efficacy in goats has not yet been studied. In this study, the sedative and alfaxalone sparing effects of midazolam and butorphanol, administered alone or concomitantly, in goats were assessed. Eight clinically healthy goats, four does and four wethers, were enlisted in a randomised crossover manner to receive intramuscular sedative treatments consisting of saline 0.05 mL/kg, or midazolam 0.30 mg/kg, or butorphanol 0.10 mg/kg, or a combination of midazolam 0.30 mg/kg with butorphanol 0.10 mg/kg before intravenous induction of general anaesthesia with alfaxalone. Following induction, the goats were immediately intubated and the quality of anaesthesia and basic physiological cardiorespiratory and blood-gas parameters were assessed until the goats had recovered from anaesthesia. The degree of sedation, quality of induction and recovery were scored. When compared with saline (3.00 mg/kg), midazolam,administered alone or with butorphanol, caused a statistically significant increased level of sedation and a reduction in the amount of alfaxalone required for induction (2.00 mg/kg and 1.70 mg/kg, respectively). Butorphanol alone (2.30 mg/kg) did not cause significant changes in level of sedation or alfaxalone-induction dose. During induction and recovery, the goats were calm following all treatments, including the control group. Cardiorespiratory and blood-gas parameters were maintained within clinically acceptable limits. The present study showed that midazolam, administered alone or combined with butorphanol, produces a degree of sedation that significantly reduces the dose of alfaxalone required for induction of general anaesthesia in goats, without causing any major adverse cardiorespiratory effects.

Effects of tramadol with tiletamine/zolazepam-xylazine as anaesthesia in cats

This study was conducted to investigate the effect of the combination of tiletamine/zolazepam-xylazine-tramadol (TZXT) in cats and to compare its efficacy as an anaesthetic technique with tiletamine/zolazepam-xylazine (TZX). Fourteen healthy thirteen-month-old cats of both sexes were immobilized by TZXT or TZX on two different occasions. The cats’ scores for immobilization, analgesia and baseline physiological indicators, heart rate, respiratory rate and rectal temperature, were recorded before and 5, 10, 15, 20, 30, 40, 50, 60, 80, 100 and 120 min after administration of TZXT or TZX. Animals in both groups became laterally recumbent within 3 min and physiological indicators changed after administration. These changes were within biologically acceptable limits; these measurements did not differ between the treatments. Induction and recovery quality in animals was better with TZXT than with TZX. Sedation, analgesia, muscle relaxation and posture scores was higher in TZXT group. During recovery, cats in TZXT group were more conscious than cats in TZX group. This study showed that in cats, addition of tramadol (T) to TZX improved the quality of anaesthetic induction and increased the analgesic effect without adversely affecting the physiological indicators. Thus tiletamine/zolazepam-xylazine-tramadol shows to be more suitable for cat anaesthesia.

AVALIAÇÃO COMPORTAMENTAL DA ANESTESIA POR ISOFLUORANO E INFUSÃO CONTÍNUA DE XILAZINA E MEDETOMIDINA EM EQUINOS

The association of an -2 agonist to an anesthetic protocol leads to deep sedation, muscle relaxation and potent analgesia, reducing the quantity of other anesthetic agents to reach the ideal anesthetic plan to the surgical procedure. This study evaluated comparatively the tranquilization, induction and recovery quality of the isofluorane anesthesia and xylazine and medetomidine continuous infusion in 16 horses. It was possible to conclude that, in this specie, the medetomidine protocol warrants wider muscle relaxation, better quality of anesthetic induction and recovery, even though it presents the same tranquilization quality of the xylazine protocol.KEYWORDS: egg quality; glutamine; intestinal morphology; thermal stress.

The pharmacokinetics and pharmacodynamics of the injectable anaesthetic alfaxalone in the horse

ObjectiveTo determine the pharmacokinetics and pharmacodynamics of the neurosteroidal anaesthetic, alfaxalone, in horses after a single intravenous (IV) injection of alfaxalone, following premedication with acepromazine, xylazine and guaiphenesin. Study designProspective experimental study. AnimalsTen (five male and five female), adult, healthy, Standardbred horses. MethodsHorses were premedicated with acepromazine (0.03 mg kg−1 IV). Twenty minutes later they received xylazine (1 mg kg−1 IV), then after 5 minutes, guaiphenesin (35 mg kg−1 IV) followed immediately by IV induction of anaesthesia with alfaxalone (1 mg kg−1). Cardiorespiratory variables (pulse rate, respiratory rate, pulse oximetry) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Venous blood samples were collected at strategic time points and plasma concentrations of alfaxalone were assayed using liquid chromatography-mass spectrometry (LC/MS) and analysed by noncompartmental pharmacokinetic analysis. The quality of anaesthetic induction and recovery was scored on a scale of 1–5 (1 very poor, 5 excellent). ResultsThe median (range) induction and recovery scores were 4 (3–5) (good: horse slowly and moderately gently attained recumbency with minimal or no rigidity or paddling) and 4 (1–5) (good: horse stood on first attempt with some knuckling and ataxia) respectively. The monitored cardiopulmonary variables were within the range expected for clinical equine anaesthesia. The mean ± SD durations of anaesthesia from induction to sternal recumbency and from induction to standing were 42.7 ± 8.4 and 47 ± 9.6 minutes, respectively. The mean ± SD plasma elimination half life (t1/2), plasma clearance (Clp) and volume of distribution (Vd) for alfaxalone were 33.4 minutes, 37.1 ± 11.1 mL minute−1 kg−1 and 1.6 ± 0.4 L kg−1, respectively. Conclusions and clinical relevanceAlfaxalone, in a 2-hydroxypropyl-beta-cyclodextrin formulation, provides anaesthesia with a short duration of recumbency that is characterised by a smooth induction and satisfactory recovery in the horse. As in other species, alfaxalone is rapidly cleared from the plasma in the horse.

Clinical efficacy and cardiorespiratory effects of alfaxalone, or diazepam/fentanyl for induction of anaesthesia in dogs that are a poor anaesthetic risk

ObjectiveTo evaluate the clinical efficacy and cardiorespiratory effects of alfaxalone as an anaesthetic induction agent in dogs with moderate to severe systemic disease. Study designRandomized prospective clinical study. AnimalsForty dogs of physical status ASA III-V referred for various surgical procedures. MethodsDogs were pre-medicated with intramuscular methadone (0.2 mg kg−1) and allocated randomly to one of two treatment groups for induction of anaesthesia: alfaxalone (ALF) 1–2 mg kg−1 administered intravenously (IV) over 60 seconds or fentanyl 5 μg kg−1 with diazepam 0.2 mg kg−1± propofol 1–2 mg kg−1 (FDP) IV to allow endotracheal intubation. Anaesthesia was maintained with isoflurane in oxygen and fentanyl infusion following both treatments. All dogs were mechanically ventilated to maintain normocapnia. Systolic blood pressure (SAP) was measured by Doppler ultrasound before and immediately after anaesthetic induction, but before isoflurane administration. Parameters recorded every 5 minutes throughout subsequent anaesthesia were heart and respiratory rates, end-tidal partial pressure of carbon dioxide and isoflurane, oxygen saturation of haemoglobin and invasive systolic, diastolic and mean arterial blood pressure. Quality of anaesthetic induction and recovery were recorded. Continuous variables were assessed for normality and analyzed with the Mann Whitney U test. Repeated measures were log transformed and analyzed with repeated measures anova (p < 0.05). ResultsTreatment groups were similar for continuous and categorical data. Anaesthetic induction quality was good following both treatments. Pre-induction and post-induction systolic blood pressure did not differ between treatments and there was no significant change after induction. The parameters measured throughout the subsequent anaesthetic procedures did not differ between treatments. Quality of recovery was very, quite or moderately smooth. Conclusions and clinical relevanceInduction of anaesthesia with alfaxalone resulted in similar cardiorespiratory effects when compared to the fentanyl-diazepam-propofol combination and is a clinically acceptable induction agent in sick dogs.

Comparison of racemic ketamine and S-ketamine as agents for the induction of anaesthesia in goats

ObjectiveTo compare racemic ketamine and S-ketamine as induction agents prior to isoflurane anaesthesia. Study designProspective, blinded, randomized experimental study. AnimalsThirty-one healthy adult goats weighing 39-86 kg. MethodsGoats were premedicated with xylazine (0.1 mg kg−1) intravenously (IV) given over 5 minutes. Each goat was assigned randomly to one of two treatments for IV anaesthetic induction: group RK (15 goats) racemic ketamine (3 mg kg−1) and group SK (16 goats) S-ketamine (1.5 mg kg−1). Time from end-injection to recumbency was measured and quality of anaesthetic induction and condition for endotracheal intubation were scored. Anaesthesia was maintained with isoflurane in oxygen for 90 minutes. Heart rate, invasive arterial blood pressure, oxygen saturation, temperature, end-tidal carbon dioxide and isoflurane were recorded every 5 minutes. Arterial blood samples were taken for analysis every 30 minutes. Recovery time to recurrence of swallowing reflex, to first head movement and to standing were recorded and recovery quality was scored. Two-way repeated measures anova, Mann-Whitney and a Mantel-Cox tests were used for statistical analysis as relevant with a significance level set at p < 0.05. ResultsInduction of anaesthesia was smooth and uneventful in all goats. There was no statistical difference between groups in any measured parameter. Side effects following anaesthetic induction included slight head or limb twitching, moving forward and backward, salivation and nystagmus but were minimal. Endotracheal intubation was achieved in all goats at first or second attempt. Recovery was uneventful on all occasions. All goats were quiet and needed only one or two attempts to stand. Conclusions and clinical relevanceS-ketamine at half the dose rate of racemic ketamine in goats sedated with xylazine and thereafter anaesthetised with isoflurane induces the same clinically measurable effects.

Alfaxalone in cyclodextrin for induction and maintenance of anaesthesia in ponies undergoing field castration

ObjectiveTo evaluate the induction and maintenance of anaesthesia using alfaxalone following pre-anaesthetic medication with romifidine and butorphanol in ponies undergoing castration in the field. Study designProspective clinical study. AnimalsSeventeen male ponies weighing 169 ± 29 kg. MethodsThe ponies were sedated with romifidine and butorphanol intravenously (IV). Induction time was recorded following administration of alfaxalone 1 mg kg−1 and diazepam 0.02 mg kg−1 IV. If movement during surgery occurred, alfaxalone 0.2 mg kg−1 was administered IV. The quality of anaesthetic induction, and recovery were scored on a subjective scale of 1 (good) to 5 (poor). The number of attempts to attain sternal recumbency and standing, quality of recovery and times from induction to end of surgery, first head lift, sternal recumbency and standing were recorded. ResultsInduction quality was good [median score (range) 1 (1–3)] with a mean ± SD time of 29 ± 6 seconds taken to achieve lateral recumbency. Ten ponies required incremental doses of alfaxalone during surgery. Mean times to the end of surgery, first head lift, sternal recumbency and standing were 26 ± 9 minutes, 31 ± 9 minutes, 33 ± 9 minutes and 34 ± 9 minutes respectively. The number of attempts to attain sternal recumbency was 1(1–1) and to attain standing was 1(1–2). Quality of recovery was good, with a recovery score of 1(1–2). Conclusions and clinical relevanceAlfaxalone provided smooth induction and recovery characteristics and was considered suitable for maintenance of anaesthesia for castration in ponies.

Comparison of the anesthetic efficacy and cardiopulmonary effects of continuous rate infusions of alfaxalone-2-hydroxypropyl-β-cyclodextrin and propofol in dogs

To compare the cardiopulmonary effects of continuous rate infusions (CRIs) of alfaxalone-2-hydroxypropyl-beta-cyclodextrin (HPCD) and propofol in healthy dogs. 6 young adult medium-sized healthy crossbred dogs. A crossover design was used with a washout period of 6 days between anesthetic treatments. Each dog was sedated with acepromazine (0.02 mg/kg, IV) and hydromorphone (0.05 mg/kg, IV). Anesthesia was induced with propofol (4 mg/kg) or alfaxalone-HPCD (2 mg/kg). After endotracheal intubation, anesthesia was maintained with the same agent (propofol, 0.25 mg/kg/min; alfaxalone-HPCD, 0.07 mg/kg/min) for 120 minutes. Dogs spontaneously breathed 100% oxygen. Measurements included end-tidal partial pressure of carbon dioxide, heart and respiratory rates, mean arterial blood pressure, thermodilution-derived cardiac output, and body temperature. Paired arterial and mixed venous blood samples were collected for determination of blood pH, PaCO(2), and PaO(2). Data were recorded prior to induction; 5, 15, 30, 60, 90, and 120 minutes after induction of anesthesia; and 20 minutes after stopping the CRI, when feasible. Stroke volume and systemic vascular resistance were calculated. Quality of anesthetic induction and recovery and interval to recovery were recorded. Both propofol and alfaxalone-HPCD produced excellent induction of anesthesia, maintenance, and recovery. Respiratory depression was evident with both anesthetics. Clinically acceptable, mild hemodynamic changes were similar for both anesthetics. Alfaxalone-HPCD produced clinically acceptable anesthetic quality and hemodynamic values ideal for use as a CRI. Ventilation may need to be supported if hydromorphone is used at these propofol and alfaxalone-HPCD infusion rates.

Fentanyl or midazolam for co-induction of anaesthesia with propofol in dogs

ObjectivePropofol may cause adverse effects (e.g. apnoea, hypotension) at induction of anaesthesia. Co-induction of anaesthesia may reduce propofol requirements. The effect of fentanyl or midazolam on propofol dose requirements and cardiorespiratory parameters was studied. Study designRandomized, controlled, blinded clinical study. AnimalsSixty-six client owned dogs (35 male, 31 female, ASA I-II, age 6–120 months, body mass 4.7–48.0 kg) were selected. MethodsPre-medication with acepromazine (0.025 mg kg−1) and morphine (0.25 mg kg−1) was administered by intramuscular injection. After 30 minutes group fentanyl-propofol (FP) received fentanyl (2 μg kg−1), group midazolam-propofol (MP) midazolam (0.2 mg kg−1) injected over 30 seconds via a cephalic catheter and in a third group, control-propofol (CP), the IV catheter was flushed with an equivalent volume of heparinized saline. Anaesthesia was induced 2 minutes later, with propofol (4 mg kg−1minute−1) administered to effect. After endotracheal intubation anaesthesia was maintained with a standardized anaesthetic protocol. Pulse rate, respiratory rate (RR) and mean arterial pressure (MAP) were recorded before the co-induction agent, before induction, and 0, 2 and 5 minutes after intubation. Apnoea ≥30 seconds was recorded and treated. Sedation after pre-medication, activity after the co-induction agent, quality of anaesthetic induction and endotracheal intubation were scored. ResultsPropofol dose requirement was significantly reduced in FP [2.90 mg kg−1(0.57)] compared to CP [3.51 mg kg−1 (0.74)] and MP [3.58 mg kg−1(0.49)]. Mean pulse rate was higher in MP than in CP or FP (p = 0.003). No statistically significant difference was found between groups in mean RR, MAP or incidence of apnoea. Activity score was significantly higher (i.e. more excited) (p = 0.0001), and quality of induction score was significantly poorer (p = 0.0001) in MP compared to CP or FP. Intubation score was similar in all groups. Conclusions and clinical relevanceFentanyl decreased propofol requirement but did not significantly alter cardiovascular parameters. Midazolam did not reduce propofol requirements and caused excitement in some animals.

Assessment of a medetomidin/propofol intravenous anaesthesia (TIVA) for clinical anaesthesia in equidae

This study investigated the clinical use of a medetomidine/propofol TIVA technique in horses. Twenty-seven equidae of mixed breed, age [mean ± SD (range)] 2.9 ± 2.74 (0.11–11) years, weight (n = 15) 237 ± 130.22 (64–470) kg were anaesthetized for the following procedures: intra-abdominal (3); castration (15); joint flush (4); screw removal (1); desmotomy (3) and dermatoma removal (1). Horses were sedated with 7 µg kg−1 medetomidine IV and 10 minutes later anaesthesia was induced with 2 mg kg−1 propofol IV. Incremental doses of medetomidine were given prior to induction if the horse lifted its head when approached. Following induction, trachea were intubated and oxygen administered at FIO2 > 90%. Anaesthesia was maintained with 3.5 µg kg−1 h−1 medetomidine IV and propofol infused to effect (initial dose 0.1 mg kg−1min−1) 1. Heart rate, respiratory rate, propofol dose and arterial blood pressure were recorded every five minutes and arterial blood gases every 15 minutes. Quality of sedation, anaesthetic induction and recovery were evaluated by the first author according to previously described scores ( Bettschart-Wolfensberger et al. 1998). Data were analysed in a preliminary manner by descriptive statistical methods. Twelve horses required additional medetomidine for adequate sedation prior to induction (2 µg kg, n = 11; 6 µg kg, n = 1). Induction to anaesthesia was variable; excellent in 3, good in 18, fair in 4 and poor (unsatisfactory) in 2 horses. In an additional horse, induction to anaesthesia was very poor and transfer from the induction area to theatre was not possible, due to limb movement, even after several IV doses of propofol (total dose 2 mg kg−1) and thiopentone (total dose 2.5 mg kg−1). The use of propofol as an induction agent was stopped after this incident. During anaesthesia, range of mean values (absolute range) were, for respiratory rate 4.8–12.4 (4–32) min−1, heart rate 36.3–46.8 (15–58) min−1, mean arterial blood pressure 95.6–111 (84–128) mm Hg, propofol infusion 0.063–0.18 mg kg−1min−1, PaO2 23.2–31.8 (11.7–59.7) kPa, PaCO2 6.1–7 (5.2–8.5) kPa. Anaesthetic quality was excellent and spontaneous movement occurred in six horses but was slow and easily controlled with increments of propofol. Anaesthetic duration was 57.9 ± 38.16 (15–175) minutes. Recovery was completed unaided within 24.3 ± 10.66 (10–44.8) minutes. It was uneventful in all horses. Medetomidine/propofol TIVA at the dose rates studied produced good quality anaesthesia with cardiopulmonary depression within ranges commonly recorded during inhalation anaesthesia in horses. However the quality of the anaesthetic induction was variable, and appeared inferior to that achieved with induction techniques which included ketamine.

Assessment of a medetomidine/propofol total intravenous anaesthesia (TIVA) for clinical anaesthesia in equidae

This study investigated the clinical use of a medetomidine/propofol TIVA technique in horses. Twenty-seven equidae of mixed breed, age [mean ± SD (range)] 2.9 ± 2.74 (0.11–11) years, weight (n = 15) 237 ± 130.22 (64–470) kg were anaesthetized for the following procedures: intra-abdominal (3); castration (15); joint flush (4); screw removal (1); desmotomy (3) and dermatoma removal (1). Horses were sedated with 7 µg kg−1 medetomidine IV and 10 minutes later anaesthesia was induced with 2 mg kg−1 propofol IV. Incremental doses of medetomidine were given prior to induction if the horse lifted its head when approached. Following induction, trachea were intubated and oxygen administered at FIO2 > 90%. Anaesthesia was maintained with 3.5 µg kg−1 h−1 medetomidine IV and propofol infused to effect (initial dose 0.1 mg kg−1min−1) 1. Heart rate, respiratory rate, propofol dose and arterial blood pressure were recorded every five minutes and arterial blood gases every 15 minutes. Quality of sedation, anaesthetic induction and recovery were evaluated by the first author according to previously described scores ( Bettschart-Wolfensberger et al. 1998). Data were analysed in a preliminary manner by descriptive statistical methods. Twelve horses required additional medetomidine for adequate sedation prior to induction (2 µg kg, n = 11; 6 µg kg, n = 1). Induction to anaesthesia was variable; excellent in 3, good in 18, fair in 4 and poor (unsatisfactory) in 2 horses. In an additional horse, induction to anaesthesia was very poor and transfer from the induction area to theatre was not possible, due to limb movement, even after several IV doses of propofol (total dose 2 mg kg−1) and thiopentone (total dose 2.5 mg kg−1). The use of propofol as an induction agent was stopped after this incident. During anaesthesia, range of mean values (absolute range) were, for respiratory rate 4.8–12.4 (4–32) min−1, heart rate 36.3–46.8 (15–58) min−1, mean arterial blood pressure 95.6–111 (84–128) mm Hg, propofol infusion 0.063–0.18 mg kg−1min−1, PaO2 23.2–31.8 (11.7–59.7) kPa, PaCO2 6.1–7 (5.2–8.5) kPa. Anaesthetic quality was excellent and spontaneous movement occurred in six horses but was slow and easily controlled with increments of propofol. Anaesthetic duration was 57.9 ± 38.16 (15–175) minutes. Recovery was completed unaided within 24.3 ± 10.66 (10–44.8) minutes. It was uneventful in all horses. Medetomidine/propofol TIVA at the dose rates studied produced good quality anaesthesia with cardiopulmonary depression within ranges commonly recorded during inhalation anaesthesia in horses. However the quality of the anaesthetic induction was variable, and appeared inferior to that achieved with induction techniques which included ketamine. Acknowledgements: The authors would like to thank Orion Corporation, Finland for the sponsorship of Domitor and Malinckrodt, UK for sponsorship of Rapinovet.

Oral Transmucosal Fentanyl Citrate for Preanesthetic Medication of Pediatric Day Surgery Patients with and without Droperidol as a Prophylactic Anti-emetic

he safety and efficacy of oral transmucosal fentanyl citrate (OTFC) as a preanesthetic medication and the efficacy of droperidol as a prophylactic anti-emetic were evaluated in 100 children aged 2-8 yr undergoing general anesthesia for outpatient surgery. Patients were randomly assigned to one of four groups and managed in a double-blinded manner: 1) placebo lozenge 45 min preoperatively and placebo (normal saline) injected intravenously after induction of anesthesia; 2) placebo lozenge 45 min preoperatively and 50 micrograms/kg droperidol intravenously after induction; 3) 15-20 micrograms/kg OTFC lozenge 45 min preoperatively and placebo intravenously after induction; and 4) 15-20 micrograms/kg OTFC lozenge 45 min preoperatively and droperidol 50 micrograms/kg intravenously after induction. Anesthesia was induced and maintained with halothane and nitrous oxide in oxygen. Heart rate, respiratory rate, blood pressure, and hemoglobin oxygen saturation (SpO2) were monitored throughout the study. Scoring systems were used to evaluate sedation, anxiety, cooperation, and ease and quality of anesthetic induction. Emergence, recovery, and discharge times were recorded. Nausea, vomiting, and adverse effects were noted. Preoperatively, children receiving OTFC had significantly greater sedation, slower respiratory rates, lower SpO2, and less excitement during induction. Postoperative nausea and vomiting occurred significantly more frequently after OTFC than after placebo. Prophylactic droperidol did not significantly reduce the incidence of nausea and vomiting. The authors conclude that, in pediatric surgical outpatients, OTFC reliably induces preoperative sedation and facilitates inhalation induction of anesthesia, but it is associated with significant decreases in respiratory rate and SpO2 and a high incidence of postoperative nausea and vomiting that is not significantly reduced by prophylactic droperidol.

Effets du propofol sur la pression intraoculaire dans la chirurgie du strabisme de l'enfant

Propofol was assessed for eye surgery in 20 children, ASA group I or II, 2–14 year-old, randomly assigned to 2 equal groups. Premedication, analgesia and muscle paralysis were similar in both groups. Group P patients were given an induction dose of 4 mg · kg −1 propofol, followed by an infusion of 15 mg · kg −1 · h −1 for the first half hour, and then 10 mg · kg −1 · h −1 to maintain anaesthesia. Group C patients were given 10 mg · kg −1 thiopentone for induction and halothane for maintenance. The quality of anaesthesia was assessed by monitoring adverse effects, heart rate, blood pressure, the length of anaesthesia, the delay of the first spontaneous breath and eye opening, and extubation. Intraocular pressure was measured before and 3 min after intubation, and 5 min after extubation. The quality of anaesthetic induction and maintenance were very similar in both groups. Pain occured more frequently at the injection site with propofol (p < 0.01). Children in group P recovered more quickly, and extubation was possible much earlier in this group (p < 0.05). However, restlessness was significantly more frequent in group P (n = 9) than in group C (n = 1) (p < 0.01). Systolic, diastolic blood pressure and heart rate were significantly lower in group P (p < 0.05 ; 0.001 ; 0.001 respectively). No significant decrease in intraocular pressure in both groups was observed. The use of propofol for eye surgery in children is acceptable, despite some restlessness during recovery.