Effects of midazolam before or after alfaxalone for co-induction of anaesthesia in healthy dogs

Comparison of the effects of propofol and alfaxalone on the electrocardiogram of dogs, with particular reference to QT interval

Cardiac electrical activity is often altered by administration of anesthetic drugs. While the effects of propofol in this regard have previously been described in dogs, to date, there are no reports of the effect of alfaxalone. This study investigated the impact of both propofol and alfaxalone on the ECG of 60 dogs, after premedication with acepromazine and methadone. Heart rate increased significantly in both groups. The PR and QRS intervals were significantly increased following propofol while with alfaxalone the QRS duration was significantly increased and ST segment depression was observed. The QT and JT interval were significantly shorter following induction with alfaxalone, but, when corrected (c) for heart rate, QTc and JTc in both groups were significantly greater following induction. When comparing the magnitude of change between groups, the change in RR interval was greater in the alfaxalone group. The change in both QT and JT intervals were significantly greater following alfaxalone, but when QTc and JTc intervals were compared, there were no significant differences between the two drugs. The similarly increased QTc produced by both drugs may suggest comparable proarrhythmic effects.

Heart rate, arterial pressure and propofol-sparing effects of guaifenesin in dogs

OBJECTIVE

To evaluate the heart rate (HR) and systemic arterial pressure (sAP) effects, and propofol induction dose requirements in healthy dogs administered propofol with or without guaifenesin for the induction of anesthesia.

STUDY DESIGN

Prospective blinded crossover experimental study.

ANIMALS

A total of 10 healthy adult female Beagle dogs.

METHODS

Dogs were premedicated with intravenous (IV) butorphanol (0.4 mg kg^-1) and administered guaifenesin 5% at 50 mg kg^-1 (treatment G50), 100 mg kg^-1 (treatment G100) or saline (treatment saline) IV prior to anesthetic induction with propofol. HR, invasive sAP and respiratory rate (f_R) were recorded after butorphanol administration, after guaifenesin administration and after propofol and endotracheal intubation. Propofol doses for intubation were recorded. Repeated measures analysis of variance (anova) was used to determine differences in propofol dose requirements among treatments, and differences in cardiopulmonary values over time and among treatments with p < 0.05 considered statistically significant.

RESULTS

Propofol doses (mean ± standard deviation) for treatments saline, G50 and G100 were 3.3 ± 1.0, 2.7 ± 0.7 and 2.1 ± 0.8 mg kg^-1, respectively. Propofol administered was significantly lower in treatment G100 than in treatment saline (p = 0.04). In treatments G50 and G100, HR increased following induction of anesthesia and intubation compared with baseline measurements. HR was higher in treatment G100 than in treatments G50 and saline following induction of anesthesia. In all treatments, sAP decreased following intubation compared with baseline values. There were no significant differences in sAP among treatments. f_R was lower following intubation than baseline and post co-induction values and did not differ significantly among treatments.

CONCLUSIONS AND CLINICAL RELEVANCE

When administered as a co-induction agent in dogs, guaifenesin reduced propofol requirements for tracheal intubation. HR increased and sAP and f_R decreased, but mean values remained clinically acceptable.

Changes in Hematological and Biochemical Profiles in Ovariohysterectomized Bitches Using an Alfaxalone–Midazolam–Morphine–Sevoflurane Protocol

Simple Summary

Laboratory tests are an integral part of the overall diagnostic procedures for both physiological and pathological conditions. Ovariohysterectomy (OHE) in bitches is an invasive procedure, producing moderate to severe pain. The response to surgical stress is characterized by a series of neuroendocrine and metabolic changes that can be represented on hematological and biochemical profiles. The objective of this study was to evaluate the physiological response to surgical stress, predict the presence of possible post-surgical complications, and where appropriate, establish the appropriate treatment based on the hematochemical changes during and after OHE in healthy bitches. OHE in this study induced transient changes in certain hematological and biochemical parameters. Knowledge of the hematochemical changes in response to stress and trauma induced by OHE in healthy dogs would allow to predict possible post-surgical complications.

Abstract

The aim of this study was to monitor hematochemical changes during and after OHE in bitches. Twenty-four females were anesthetized with alfaxalone, midazolam, morphine and sevoflurane. Blood samples were taken before anesthesia (T0), at 30 (T1), and 60 min (T2), at 3 (T3), 6 (T4), 12 (T5), and 24 h (T6), and at 3 (T7) and 7 days (T8) from the start of surgery. Red blood cells (RBC) and packed cell volume (PCV) decreased significantly from T1 to T5 and hemoglobin (HB) concentration from T4 to T6. Both the white blood cell (WBC) and neutrophil (NFS) count increased significantly from T3 to T6, monocyte (MON) from T2 to T5, and eosinophil (EOS) at T5. Platelet (PLT) and plateletcrit (PCT) significantly decreased at T5 and increased from T6 to T8; platelet distribution width (PDW) increased significantly from T3 to T6. Creatine kinase (CK) activity increased significantly from T5 to T7. Glucose (GLU) concentrations increased significantly at T2 and P from T2 to T3. TG levels decreased from T2 to T4 and blood urea nitrogen (BUN) levels from T1 to T7, subsequently increasing until T8. Changes possibly resulting from stress and surgical trauma, as well as hemodilution and splenic storage, are due to anesthesia and surgery. In healthy bitches, these changes tend to gradually stabilize after the ending of OHE. A post-operative follow-up is essential to detect possible post-operative complications.

Clinical review of the pharmacological and anaesthetic effects of alfaxalone in dogs

This clinical review summarises the pharmacological and anaesthetic properties of alfaxalone in the dog. Available pharmacokinetic-pharmacodynamic data and factors affecting the induction dose have been reported. Furthermore, quality of induction and recovery after alfaxalone administration, the use of alfaxalone for total intravenous anaesthesia, and its effects on the cardio-respiratory system, on laryngeal motion, on intraocular pressure and tear production have been evaluated. Finally, the use of alfaxalone in dogs undergoing caesarean section and the effect of intramuscular alfaxalone administration have been considered.

Scoping review of quality of anesthetic induction and recovery scales used for dogs

OBJECTIVE

To compare, describe and assess the level of validation of all instruments measuring quality of induction and recovery from anesthesia in dogs.

DATABASES USED

A search was performed using the electronic database PubMed to find articles containing an induction quality scale, a recovery quality scale or both in dogs. Articles not directly accessible through PubMed were obtained through the Auburn University Library website and Google Scholar. The phrases 'induction scoring systems dogs', 'recovery scoring systems dogs', 'anesthetic induction score dogs', and 'anesthetic recovery score dogs' were used for searches using the 'best match search' function. The time frame searched was from 1980 to May 2020. The search was conducted from March 2020 to May 2020.

CONCLUSIONS

A thoroughly tested and validated scale for measuring the quality of induction and recovery does not exist in the current veterinary literature. A large disagreement exists between studies on the use of induction and recovery scales, and many have reported inconsistent results with current instruments. It is recommended that an induction and recovery scale intended for wide-scale use be constructed and tested extensively for psychometric validation and reliability.

Comparison between three dosages of intramuscular alfaxalone and a ketamine-dexmedetomidine-midazolam-tramadol combination in golden-headed lion tamarins (Leontopithecus chrysomelas)

OBJECTIVES

To characterize the cardiopulmonary and anesthetic effects of alfaxalone at three dose rates in comparison with a ketamine-dexmedetomidine-midazolam-tramadol combination (KDMT) for immobilization of golden-headed lion tamarins (GHLTs) (Leontopithecus chrysomelas) undergoing vasectomy.

STUDY DESIGN

Prospective clinical trial.

ANIMALS

A total of 19 healthy, male, wild-caught GHLTs.

METHODS

Tamarins were administered alfaxalone intramuscularly (IM) at 6, 12 or 15 mg kg^-1, or KDMT, ketamine (15 mg kg^-1), dexmedetomidine (0.015 mg kg^-1), midazolam (0.5 mg kg^-1) and tramadol (4 mg kg^-1) IM. Immediately after immobilization, lidocaine (8 mg kg^-1) was infiltrated subcutaneously (SC) at the incision site in all animals. Physiologic variables, anesthetic depth and quality of immobilization were assessed. At the end of the procedure, atipamezole (0.15 mg kg^-1) was administered IM to group KDMT and tramadol (4 mg kg^-1) SC to the other groups; all animals were injected with ketoprofen (2 mg kg^-1) SC.

RESULTS

A dose-dependent increase in sedation, muscle relaxation and immobilization time was noted in the alfaxalone groups. Despite the administration of atipamezole, the recovery time was longer for KDMT than all other groups. Muscle tremors were noted in some animals during induction and recovery with alfaxalone. No significant differences were observed for cardiovascular variables among the alfaxalone groups, whereas an initial decrease in heart rate and systolic arterial blood pressure was recorded in KDMT, which increased after atipamezole administration.

CONCLUSIONS AND CLINICAL RELEVANCE

Alfaxalone dose rates of 12 or 15 mg kg^-1 IM with local anesthesia provided good sedation and subjectively adequate pain control for vasectomies in GHLTs. KDMT induced a deeper plane of anesthesia and should be considered for more invasive or painful procedures. All study groups experienced mild to moderate hypothermia and hypoxemia; therefore, the use of more efficient heating devices and oxygen supplementation is strongly recommended when using these protocols.

Anesthetic Effects of Alfaxalone-Ketamine, Alfaxalone-Ketamine-Dexmedetomidine, and Alfaxalone-Butorphanol-Midazolam Administered Intramuscularly in Five striped Palm Squirrels ( Funambulus pennantii)

Injectable anesthesia protocols for five striped palm squirrels (Funambulus pennantii) are poorly described in the literature. In this study, male intact squirrels received intramuscular injections of either alfaxalone (6 mg/kg) and ketamine (40 mg/ kg; AK group, n = 8); alfaxalone (6 mg/kg), ketamine (20 mg/kg), and dexmedetomidine (0.1 mg/kg; AKD group, n = 8); or alfaxalone (8 mg/kg), butorphanol (1 mg/kg), and midazolam (1 mg/kg; ABM group, n = 8). Atipamezole (0.15 mg/kg IM) and flumazenil (0.1 mg/kg IM) were administered 40 min after anesthesia induction (defined as loss of the righting reflex) with AKD and ABM, respectively. Heart rate, respiratory rate, rectal temperature, and reflexes were recorded every 5 min during anesthesia. Anesthetic induction was rapid in all groups (AK: median, 49 s; range, 33 to 60 s; AKD, 60 s; 54 to 70 s; and ABM, 15 s; 5 to 58 s). The anesthetic duration (from induction to full recovery) for the AK group was 62 ± 3 min (mean ± 1 SD). There was no statistically significant difference between the ABM and AKD groups regarding recovery time after partial antagonist administration and was 51 ± 5 and 48 ± 5 min, respectively. All AK animals showed twitching and abnormal vocalization during recovery. The righting reflex was absent in all squirrels for 20 min in the AK treatment group and throughout the 40 min anesthetic period in the AKD and ABM groups. The frontlimb withdrawal response was absent in all squirrels for the 40 min anesthetic period in the AKD and ABM groups, with variable responses for the AK treatment. All tested protocols in this study provided safe and effective immobilization in five striped palm squirrels, but oxygen and thermal support were indicated. Anesthetic depth must be determined before surgical procedures are performed in palm squirrels anesthetized by using these regimens.

Anaesthetic management and complications of transvascular patent ductus arteriosus occlusion in dogs

OBJECTIVE

To retrospectively analyse the anaesthetic management, complications and haemodynamic changes in a cohort of dogs undergoing transvascular patent ductus arteriosus (PDA) occlusion in a tertiary referral centre (from January 2017 to August 2018).

STUDY DESIGN

Retrospective study.

ANIMALS

A total of 49 client-owned dogs.

METHODS

Anaesthetic records of dogs with PDA that underwent transvascular occlusion of the ductus were reviewed. Anaesthetic complications evaluated included tachycardia [heart rate (HR) > 160 beats minute^-1], bradycardia (HR < 50 beats minute^-1), hypertension [systolic arterial pressure (SAP) > 150 mmHg], hypotension [mean arterial pressure (MAP) < 60 mmHg], hypothermia (<37 °C) and the presence of arrhythmias. Cardiovascular variables [HR and invasive SAP, MAP and diastolic arterial pressure (DAP)] at the time of occlusion device deployment (time 0) were compared with variables at 5 and 10 minutes after deployment. Descriptive statistics, Shapiro-Wilk test and repeated measures analysis of variance followed by a Dunnett's post hoc test were used to analyse the data (p < 0.05).

RESULTS

Crossbreed dogs were the most commonly represented followed by the Cavalier King Charles Spaniel. The median age was 8 (2-108) months, and female dogs were over-represented (65.3%). The most common American Society of Anesthesiologists score was III. Mean duration of anaesthesia was 96 ± 26 minutes and mean surgery time was 58 ± 21 minutes. Acepromazine with methadone was the most commonly used premedication combination (77.6%). Propofol was the most common induction agent (73.5%). General anaesthesia was maintained with isoflurane in oxygen in all dogs. Complications included hypotension (63%), hypothermia (34%), bradycardia (28%), arrhythmias (16%), hypertension (16%) and haemorrhage (2%). MAP and DAP increased significantly 10 minutes after device deployment compared with time 0.

CONCLUSIONS

and clinical relevance: Hypotension was the most common complication reported in dogs undergoing transvascular PDA occlusion. No major adverse events were documented.

Dose and cardiopulmonary effects of propofol alone or with midazolam for induction of anesthesia in critically ill dogs

OBJECTIVE

To determine the dose and cardiopulmonary effects of propofol alone or with midazolam for induction of anesthesia in American Society of Anesthesiologists status ≥III dogs requiring emergency abdominal surgery.

STUDY DESIGN

Prospective, randomized, blinded, clinical trial.

ANIMALS

A total of 19 client-owned dogs.

METHODS

Dogs were sedated with fentanyl (2 μg kg^-1) intravenously (IV) for instrumentation for measurement of heart rate, arterial blood pressure, cardiac index, systemic vascular resistance index, arterial blood gases, respiratory rate and rectal temperature. After additional IV fentanyl (3 μg kg^-1), the quality of sedation was scored and cardiopulmonary variables recorded. Induction of anesthesia was with IV propofol (1 mg kg^-1) and saline (0.06 mL kg^-1; group PS; nine dogs) or midazolam (0.3 mg kg^-1; group PM; 10 dogs), with additional propofol (0.25 mg kg^-1) IV every 6 seconds until endotracheal intubation. Induction/intubation quality was scored, and anesthesia was maintained with isoflurane. Variables were recorded for 5 minutes with the dog in lateral recumbency, breathing spontaneously, and then in dorsal recumbency with mechanical ventilation for the next 15 minutes. A general linear mixed model was used with post hoc analysis for multiple comparisons between groups (p < 0.05).

RESULTS

There were no differences in group demographics, temperature and cardiopulmonary variables between groups or within groups before or after induction. The propofol doses for induction of anesthesia were significantly different between groups, 1.9 ± 0.5 and 1.1 ± 0.5 mg kg^-1 for groups PS and PM, respectively, and the induction/intubation score was significantly better for group PM.

CONCLUSIONS AND CLINICAL RELEVANCE

Midazolam co-induction reduced the propofol induction dose and improved the quality of induction in critically ill dogs without an improvement in cardiopulmonary variables, when compared with a higher dose of propofol alone.

Comparison of intramuscular administration of alfaxalone-ketamine-dexmedetomidine and alfaxalone-butorphanol-midazolam in naked mole-rats (Heterocephalus glaber)

OBJECTIVE

To compare anesthetic effects of alfaxalone-ketamine-dexmedetomidine (AKD) and alfaxalone-butorphanol-midazolam (ABM) in naked mole-rats (Heterocephalus glaber).

ANIMALS

20 naked mole-rats.

PROCEDURES

Naked mole-rats received AKD (alfaxalone, 2 mg/kg; ketamine, 20 mg/kg; and dexmedetomidine, 0.02 mg/kg; n = 10) or ABM (alfaxalone, 2 mg/kg; butorphanol, 2 mg/kg; and midazolam, 1 mg/kg; 9) IM; 1 animal was removed from the study. Atipamezole (I mg/kg) and flumazenil (0.1 mg/kg) were administered 40 minutes after anesthetic induction (defined as loss of the righting reflex) with AKD and ABM, respectively. Heart rate, respiratory rate, oxygen saturation, and reflexes were recorded every 5 minutes.

RESULTS

The ABM group had significantly longer median times for induction and recovery than the AKD group. Administration of ABM resulted in significantly lower respiratory rates than administration of AKD from time of anesthetic induction to 10 minutes after induction. Respiratory rate significantly decreased in the AKD group from I0 minutes after induction through the end of the anesthetic period but did not change over time in the ABM group. Males had higher respiratory rates in both groups. Loss of the righting reflex was still evident 40 minutes after induction in both groups. In the AKD group, all tested reflexes were absent from I0 to 40 minutes after induction; the ABM group had variable reflexes that recovered within individual animals over time.

CONCLUSIONS AND CLINICAL RELEVANCE

Both AKD and ABM provided effective immobilization in naked mole-rats, but AKD appeared to provide more consistent and deeper anesthesia, compared with administration of ABM.

Effects of ketamine or midazolam continuous rate infusions on alfaxalone total intravenous anaesthesia requirements and recovery quality in healthy dogs: a randomized clinical trial

OBJECTIVE

To determine the alfaxalone dose reduction during total intravenous anaesthesia (TIVA) when combined with ketamine or midazolam constant rate infusions and to assess recovery quality in healthy dogs.

STUDY DESIGN

Prospective, blinded clinical study.

ANIMALS

A group of 33 healthy, client-owned dogs subjected to dental procedures.

METHODS

After premedication with intramuscular acepromazine 0.05 mg kg^-1 and methadone 0.3 mg kg^-1, anaesthetic induction started with intravenous alfaxalone 0.5 mg kg^-1 followed by either lactated Ringer's solution (0.04 mL kg^-1, group A), ketamine (2 mg kg^-1, group AK) or midazolam (0.2 mg kg^-1, group AM) and completed with alfaxalone until endotracheal intubation was achieved. Anaesthesia was maintained with alfaxalone (6 mg kg^-1 hour^-1), adjusted (±20%) every 5 minutes to maintain a suitable level of anaesthesia. Ketamine (0.6 mg kg^-1 hour^-1) or midazolam (0.4 mg kg^-1 hour^-1) were employed for anaesthetic maintenance in groups AK and AM, respectively. Physiological variables were monitored during anaesthesia. Times from alfaxalone discontinuation to extubation, sternal recumbency and standing position were calculated. Recovery quality and incidence of adverse events were recorded. Groups were compared using parametric analysis of variance and nonparametric (Kruskal-Wallis, Chi-square, Fisher's exact) tests as appropriate, p < 0.05.

RESULTS

Midazolam significantly reduced alfaxalone induction and maintenance doses (46%; p = 0.034 and 32%, p = 0.012, respectively), whereas ketamine only reduced the alfaxalone induction dose (30%; p = 0.010). Recovery quality was unacceptable in nine dogs in group A, three dogs in group AK and three dogs in group AM.

CONCLUSIONS AND CLINICAL RELEVANCE

Midazolam, but not ketamine, reduced the alfaxalone infusion rate, and both co-adjuvant drugs reduced the alfaxalone induction dose. Alfaxalone TIVA allowed anaesthetic maintenance for dental procedures in dogs, but the quality of anaesthetic recovery remained unacceptable irrespective of its combination with ketamine or midazolam.

Pharmacokinetics and sedative effects of alfaxalone with or without dexmedetomidine in rabbits

This study aimed to investigate the specific pharmacokinetic profile and effects of alfaxalone after intravenous (IV) and intramuscular (IM) administration to rabbits and evaluate the potential interaction with dexmedetomidine. The study design was a blinded, randomized crossover with a washout period of 2 weeks. Five New Zealand white rabbits were used. Each animal received single IV and IM injections of alfaxalone at a single dose of 5 mg/kg, and single IV and IM injections of alfaxalone (5 mg/kg) combined with dexmedetomidine (100 μg/kg) administered intramuscularly. Blood samples were collected at predetermined times and analysed by high-performance liquid chromatography. The plasma concentration-time curves were analysed by non-compartmental analysis. Sedation/anaesthesia scores were evaluated by a modified numerical rating scale. At pre-determined time points heart and respiratory rates were measured. Times to sternal recumbency and standing position during the recovery were recorded. Concentrations of alfaxalone alone were very similar (slighty smaller) to concentrations when alfaxalone was combined with dexmedetomidine, after both routes of administration. Dexmedetomidine enhanced and increase the duration of the sedative effects of alfaxalone. In conclusion, alfaxalone administered in rabbits provides rapid and smooth onset of sedation. After IV and IM injections of alfaxalone combined with dexmedetomidine, a longer MRT and a deeper and extended sedation have been obtained compared to alfaxalone alone. Consequently, alfaxalone alone or in combination with dexmedetomidine could be useful to achieve respectively moderate to deep sedation in rabbits.

The effect of midazolam or lidocaine administration prior to etomidate induction of anesthesia on heart rate, arterial pressure, intraocular pressure and serum cortisol concentration in healthy dogs

OBJECTIVE

To evaluate selected effects of midazolam or lidocaine administered prior to etomidate for co-induction of anesthesia in healthy dogs.

STUDY DESIGN

Prospective crossover experimental study.

ANIMALS

A group of 12 healthy adult female Beagle dogs.

METHODS

Dogs were premedicated with intravenous (IV) butorphanol (0.3 mg kg^-1), and anesthesia was induced with etomidate following midazolam (0.3 mg kg^-1), lidocaine (2 mg kg^-1) or physiologic saline (1 mL) IV. Heart rate (HR), arterial blood pressure, respiratory rate (f_R) and intraocular pressure (IOP) were recorded following butorphanol, after co-induction administration, after etomidate administration and immediately following intubation. Baseline IOP values were also obtained prior to sedation. Etomidate dose requirements and the presence of myoclonus, as well as coughing or gagging during intubation were recorded. Serum cortisol concentrations were measured prior to premedication and 6 hours following etomidate administration.

RESULTS

Blood pressure, f_R and IOP were similar among treatments. Blood pressure decreased in all treatments following etomidate administration and generally returned to sedated values following intubation. HR increased following intubation with midazolam and lidocaine but remained stable in the saline treatment. The dose of etomidate (median, interquartile range, range) required for intubation was lower following midazolam (2.2, 2.1-2.6, 1.7-4.1 mg kg^-1) compared with lidocaine (2.7, 2.4-3.6, 2.2-5.1 mg kg^-1, p = 0.012) or saline (3.0, 2.8-3.8, 1.9-5.1 mg kg^-1, p = 0.015). Coughing or gagging was less frequent with midazolam compared with saline. Myoclonus was not observed. Changes in serum cortisol concentrations were not different among treatments.

CONCLUSIONS AND CLINICAL RELEVANCE

Midazolam administration reduced etomidate dose requirements and improved intubation conditions compared with lidocaine or saline treatments. Neither co-induction agent caused clinically relevant differences in measured cardiopulmonary function, IOP or cortisol concentrations compared with saline in healthy dogs. Apnea was noted in all treatments following the induction of anesthesia and preoxygenation is recommended.

Co-induction of anaesthesia with alfaxalone and midazolam in dogs: a randomized, blinded clinical trial

OBJECTIVE

To qualitatively assess the co-induction of anaesthesia with midazolam and alfaxalone and to determine cardiovascular or respiratory alterations compared with alfaxalone alone.

STUDY DESIGN

A randomized, blinded, clinical trial.

ANIMALS

A total of 29 American Society of Anesthesiologists grade I or II, client-owned dogs undergoing elective orthopaedic or soft tissue surgery.

METHODS

All dogs received 0.02 mg kg^-1 acepromazine and 0.3 mg kg^-1 methadone intramuscularly 30 minutes prior to anaesthesia. Measurements of heart rate (HR), respiratory frequency and blood pressure (BP) were assessed pre-induction and at 0, 2 and 5 minutes post-induction. Anaesthesia was induced with 0.5 mg kg^-1 alfaxalone followed by either 0.4 mg kg^-1 midazolam intravenously (group M) or an equal volume of saline (group S). Conditions were assessed for intubation and further boluses of 0.25 mg kg^-1 alfaxalone were given as required. Response to co-induction, ease of intubation and quality of induction were scored, and total dose of alfaxalone required for intubation was recorded. Repeated measures one-way analysis of variance with post hoc Tukey's test was used to assess within group changes over time and Student t tests were used to compare between groups. Incidence of apnoea was assessed using a Fisher's exact test. Data are shown as mean ± standard deviation.

RESULTS

Group M included 14 dogs and group S 15 dogs. There was a significant difference in the total dose of alfaxalone required for intubation, 0.65 ± 0.20 mg kg^-1 group M and 0.94 ± 0.26 mg kg^-1 group S (p = 0.002). Apnoea occurred significantly more frequently in group M (p = 0.007). There were no clinically significant differences in HR or BP at the measured time points between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Co-induction with midazolam had significant alfaxalone-sparing effects with no clinically detectable cardiovascular changes. Apnoea is common after co-induction.