Accuracy of drawing up liquid medications by veterinary anaesthetists and nurses.

OBJECTIVE: To evaluate the accuracy with which veterinary anaesthetists and nurses of different experience draw up small volumes of liquid. STUDY DESIGN: Prospective blinded randomized study. METHODS: A group of seven European College of Veterinary Anaesthesia and Analgesia (ECVAA) diplomates, six ECVAA residents and six anaesthesia nurses participated in the study. For each participant, five target volumes between 0.01 and 1.0 mL were randomly allocated. They were drawn up 20 times in random order using a 1 mL syringe attached to a 23 gauge needle. A total of 1900 measurements were analysed. An investigator filled the syringe and needle dead space with water for injection before each experiment. The change in mass of the syringe once filled to the target volume was used to calculate the actual volume of liquid drawn up. RESULTS: Large errors were made with measurements < 0.04 mL, so they were excluded from the statistical analysis. There was a significant effect of the target volume (p < 0.001) and of the order (p < 0.01). For each mL increase in the target volume, the absolute error decreased by 4% and from the first to the hundredth withdrawal each participant's absolute error decreased by 1%. The target volume was underestimated in 52.3% of measurements, 42% were overestimated and 5.7% were on target. None of the between-subject predictor variables approached significance. CONCLUSIONS AND CLINICAL RELEVANCE: Accuracy of veterinary anaesthetists and nurses in drawing up medications decreases as the target volume becomes smaller. Small veterinary patients receive small volumes of anaesthetic drugs with higher risks of overdosing compared with larger dogs. Years of experience and staff grade are not associated with greater accuracy. Large percentage errors may be seen with target volumes less than 0.04 mL. Dilutions are recommended for volumes > 0.19 mL in 1 mL syringe.

Evaluation of urine specific gravity as a predictor of hypotension during anaesthesia in healthy dogs premedicated with dexmedetomidine.

OBJECTIVE: To investigate the relationship between urine specific gravity (USG) and the risk of arterial hypotension during general anaesthesia (GA) in healthy dogs premedicated with dexmedetomidine and methadone. STUDY DESIGN: Prospective clinical cohort study. ANIMALS: A total of 75 healthy client-owned dogs undergoing GA for elective tibial plateau levelling osteotomy. METHODS: After placing an intravenous catheter, dogs were premedicated with dexmedetomidine (5 µg kg-1) and methadone (0.3 mg kg-1) intravenously. After induction of GA with alfaxalone to effect, the bladder was expressed and USG measured. An arterial catheter was placed, and residual blood was used to measure packed cell volume (PCV) and total protein (TP). GA was maintained with isoflurane vaporised in oxygen and a femoral and sciatic nerve block were performed. Arterial blood pressure < 60 mmHg was defined as hypotension and recorded by the anaesthetist. Treatment for hypotension was performed in a stepwise manner following a flow chart. Frequency of hypotension, treatment and response to treatment were recorded. Logistic regression modelling was used to assess the association between USG, TP and PCV and incidence of perioperative hypotension; p < 0.05. RESULTS: Data from 14 dogs were excluded. Of the 61 dogs, 16 (26%) were hypotensive during GA, 15 dogs needed treatment of which 12 were responsive to a decrease in inhalant vaporiser setting. The logistic regression model was not statistically significant (p = 0.8). There was no significant association between USG (p = 0.6), TP (p = 0.4), PCV (p = 0.8) and arterial hypotension during GA. CONCLUSIONS AND CLINICAL RELEVANCE: In healthy dogs premedicated with dexmedetomidine and methadone and maintained under GA with isoflurane and a femoral and sciatic nerve block, there was no relationship between the specific gravity of urine collected after premedication and intraoperative arterial hypotension.

A prospective, masked, randomized, controlled superiority study comparing the incidence of corneal injury following general anesthesia in dogs with two methods of corneal protection.

OBJECTIVE: To compare the incidence of corneal injury during general anesthesia (GA) and the immediate post-operative period in eyes protected with topical ocular lubricant alone with eyes protected with topical lubricant followed by complete eyelid closure using tape. ANIMALS STUDIED: One hundred client-owned dogs (200 eyes) undergoing GA for MRI scan. METHODS: Patients had ocular lubricant applied to both eyes upon induction of anesthesia. One eye was taped closed immediately after induction for the duration of anesthesia using Strappal® tape (BSN medical™; treatment group), and the other eye was not taped (control group). Eyes were randomly allocated to a treatment group. Ophthalmic examination was performed before and after anesthesia; the examiner was masked to eye treatment groups. Corneal injury was defined as corneal ulceration or corneal erosion. A McNemar's test was used to compare the incidence of corneal injury between groups. A paired-samples t-test was used to compare Schirmer-1 tear test (STT-1) readings between groups. RESULTS: Sixteen eyes (8%) developed corneal erosion. No corneal ulceration occurred. There was no significant difference between incidence of corneal erosion between groups (p = .454). There was a significant decrease in STT-1 readings following GA in both groups (p < .001), with no significant difference in STT-1 between groups (p = .687). No adverse effects of taping the eye closed were observed. CONCLUSION: Taping the eyes closed during GA had no additional benefit to the lubrication protocol used in this study.

Effect of preoperative administration of atenolol to dogs with pulmonic stenosis undergoing interventional procedures.

BACKGROUND: Beta-blockade is sometimes used in dogs with pulmonic stenosis with the intent of reducing frequency of ventricular arrhythmias during right heart catheterization. OBJECTIVES: To evaluate if pretreatment with atenolol reduces frequency of ventricular arrhythmias, anesthetist interventions, or shortens procedure time. ANIMALS: Thirty dogs with pulmonic stenosis scheduled for interventional procedures. METHODS: Single center, prospective, randomized, open-label study. Dogs were randomized to treatment with atenolol or no treatment preoperatively for a minimum of 10 days. Variables recorded included heart rate, arrhythmias and complexity, total procedure time and administration of antiarrhythmic treatment, vasopressors, positive chronotropes, or fluid boluses. RESULTS: Fifteen dogs were enrolled in each group. Dogs receiving atenolol had lower mean heart rates during the procedure (atenolol 100 ± 11 bpm vs untreated 115 ± 19 bpm, P = .01). There were no significant differences between the atenolol and untreated groups in the frequency of ventricular ectopic complexes (535 [6-5296] vs 553 [79-2863], P = .9), ventricular couplets (46 [0-481] vs 29 [3-121], P = .59), ventricular triplets (20 [0-265] vs 16 [1-82], P = .67), ventricular tachycardia (8 [0-224] vs 8 [1-118], P = .99), proportion exhibiting R-on-T phenomenon (11/15 vs 14/15, P = .33), proportion receiving intraoperative lidocaine (1/15 vs 3/15, P = .6), vasopressors/positive chronotropes (11/15 vs 5/15, P = .06), or fluid boluses (12/15 vs 7/15, P = .13). The procedure time was similar (atenolol 41 [23-68] min vs untreated 35 [18-98] min, P = .91). CONCLUSIONS AND CLINICAL IMPORTANCE: No benefit of preoperative atenolol treatment was identified in this small group of dogs.

Variation in syringes and needles dead space compared to the International Organization for Standardization standard 7886-1:2018.

OBJECTIVE: To measure the dead space of various syringe volumes and brands and a range of needles gauges commonly used in clinical practice, and to compare the results to the International Organization for Standardization (ISO) standard 7886-1:2018. STUDY DESIGN: Prospective observational study. METHODS: Syringes of five brands and seven volumes: 1, 2.5, 5, 10, 20, 30, and 60 mL, 10 of each, 10 1 mL low dead space syringes and 10 23, 21 and 18 gauge needles were analysed. Syringe dead space was estimated by weighing each syringe, drawing up and expelling its rated volume of water for injection and re-weighing the syringe. The difference in mass between the two measurements was calculated and converted to a volume based on the density of water. The dead space of the needles was estimated using a similar technique: each needle was attached to a 1 mL syringe of known dead space. A Mettler electronic balance was used for the measurements. Mean dead space was calculated for each syringe volume and needle gauge. Data were compared to the ISO standard. RESULTS: Syringe dead space for 1 and 2.5 mL was less than 0.07 mL. For 5 mL syringes four of five brands, and for 10 mL syringes one of five brands failed to comply with the ISO; the dead space was greater than 0.075 and 0.1 mL, respectively. For the 20, 30, 60 mL syringes the dead space was less than 0.2 mL. Needle dead space was 0.05 mL for 23 and 21 gauge, and 0.07 mL for 18 gauge, similar in order of magnitude to syringe dead space. CONCLUSIONS: The dead space of syringes differs between brands, and some do not meet the ISO standard. When calculating the amount of drug lost due to dead space, both that of the syringe and needle used should be considered.

The effect of neuraxial morphine on postoperative pain in dogs after extrahepatic portosystemic shunt attenuation.

OBJECTIVE: To investigate the analgesic effect of epidural morphine after surgical extrahepatic portosystemic shunt (EHPSS) attenuation. STUDY DESIGN: Randomized clinical trial. ANIMALS: A total of 20 dogs with a congenital EHPSS. METHODS: Dogs were randomly allocated to be given either a single epidural dose of 0.2 mg kg-1 preservative-free morphine (group M) or not (group C) before surgery. All dogs were administered 0.3 mg kg-1 methadone intravenously (IV) as preanaesthetic medication. Pain scores were determined every 2 hours for the first 24 hours postoperatively using the short-form Glasgow Composite Measure Pain Scale (GCMPS-SF). Dogs with a GCMPS-SF pain score >4/20 or >5/24 received 0.1 mg kg-1 methadone IV as rescue analgesia and were reassessed 30 minutes later. If more than three doses of methadone were administered in a 2 hour period, alternative pain relief was provided and a treatment failure recorded. The GCMPS-SF pain scores and number of rescue analgesia injections were analysed over 24 hours. The last observation carried forward method was applied in case of treatment failure. Food consumption and time to first urination were recorded. Data were analysed using a Mann-Whitney U test and presented as median (minimum-maximum range), with significance set at p < 0.05. RESULTS: Group M showed lower GCMPS-SF pain scores [15 (11-41) versus 31 (11-86); p = 0.023] and lower postoperative methadone requirements [0 (0-0.2) versus 0.25 (0-0.5) mg kg-1; p = 0.029] than group C. There were three treatment failures in group C only. Food consumption and time to first urination did not differ between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Epidural morphine reduced the requirement for postoperative analgesia in this study population.

Do the Manual or Computer-Controlled Flowmeters Generate Similar Isoflurane Concentrations in Tafonius?

Introduction: Tafonius is an anesthesia machine with computer-controlled monitor and ventilator. We compared the isoflurane fluctuations in the circuit with manual (MF) or computer-driven (CF) flowmeters, investigated the origin of the differences and assessed whether isoflurane concentration time course followed a one-compartment model. Material and Methods: A calibrated TEC-3 isoflurane vaporizer was used. Gas composition and flows were measured using a multiparametric monitor and a digital flowmeter. Measurements included: (1) Effects of various FiO2 with MF/CF on the isoflurane fraction changes in the breathing system during mechanical ventilation of a lung model; wash-in kinetic was fitted to a compartmental model; (2) Gas outflow at the common gas outlet (CGO) with MF/CF at different FiO2; (3) Isoflurane output of the vaporizer at various dial settings with MF/CF set at different flows without and with reduction of the CGO diameter. Results: (1) The 3% targeted isoflurane concentration was not reached; additional time was required to reach specific concentrations with CF (lowest FiO2, longer time). The exponential course fitted a two-compartment model; (2) Set and measured flows were identical with MF. With CF at 0.21 FiO2, flow was intermittently 7.6 L min-1 or zero (mean total: 38% of the set flow); with CF at 1.00 FiO2, flow was 10.6 L min-1 or zero (mean: 4-5.3 L min-1); with 0.21 < FiO2 < 1.00, combined flow was intermittent (maximum output: 15.6 L min-1); (3) With MF, isoflurane output was matching dial setting at 5 L min-1 but was lower at higher flows; with CF generating intermittent flows, isoflurane output was fluctuating. With the 4 mm diameter CGO, isoflurane concentration was close to dial setting with both MF and CF. With a 14 G CGO, isoflurane concentration was lower than dial setting with MF, higher with CF. Conclusions and Clinical Relevance: Using MF or CF led to different isoflurane fraction time course in Tafonius. Flows were lower than set with CF; the TEC-3 did not compensate for high/intermittent flows and pressures; the CGO diameter influenced isoflurane output.

Incidence of perianaesthetic complications experienced during feline bronchoscopy: a retrospective study.

OBJECTIVES: The aim of this study was to report the incidence of anaesthetic complications associated with feline bronchoscopy. METHODS: This was a retrospective analysis of anaesthetic records and electronic case logs of feline bronchoscopies at two university hospitals (centres B and L) between January 2013 and December 2015. A two-tailed Fisher's exact test was used for comparison of variables and outcomes between centres. RESULTS: Seventy-nine cases were included. Desaturation (SpO2 <90%) was the most frequently encountered complication, reported in 24 cats (30.3%); centre B reported significantly less desaturation than centre L (22.4% vs 52.4%; P = 0.014). The use of an endotracheal tube or laryngeal mask airway resulted in a lower incidence of desaturation (22.9% vs 22.2%) than the use of a tracheal catheter through which oxygen was insufflated (48.0%). The latter method was associated with an increased incidence of desaturation (P = 0.034). Patients to which terbutaline was administered had a lower incidence of desaturation (27.5%) than those that did not receive it (35.7%), although this was not statistically significant (P = 0.46). Airway management method and the use of terbutaline differed significantly between centres, as did the profile of complications. Pneumothorax was encountered in two cats (2.5%) and cardiac arrest resulting in the death in one of these cats (1.3%). CONCLUSIONS AND RELEVANCE: Desaturation is a frequently encountered complication during and after bronchoscopy. Airway management method and the use and timing of terbutaline warrant prospective evaluation for their role in decreasing the incidence of desaturation. Bronchoscopy is a high-risk procedure with frequent requirement for post-procedure oxygen supplementation. Pneumothorax and cardiac arrest are potential complications.

Regional ventilation distribution and dead space in anaesthetized horses treated with and without continuous positive airway pressure: novel insights by electrical impedance tomography and volumetric capnography.

OBJECTIVE: The aim of this study was to evaluate the effect of continuous positive airway pressure (CPAP) on regional distribution of ventilation and dead space in anaesthetized horses. STUDY DESIGN: Randomized, experimental, crossover study. ANIMALS: A total of eight healthy adult horses. METHODS: Horses were anaesthetized twice with isoflurane in 50% oxygen and medetomidine as continuous infusion in dorsal recumbency, and administered in random order either CPAP (8 cmH2O) or NO CPAP for 3 hours. Electrical impedance tomography (and volumetric capnography (VCap) measurements were performed every 30 minutes. Lung regions with little ventilation [dependent silent spaces (DSSs) and nondependent silent spaces (NSSs)], centre of ventilation (CoV) and dead space variables, as well as venous admixture were calculated. Statistical analysis was performed using multivariate analysis of variance and Pearson correlation. RESULTS: Data from six horses were statistically analysed. In CPAP, the CoV shifted to dependent parts of the lungs (p < 0.001) and DSSs were significantly smaller (p < 0.001), while no difference was seen in NSSs. Venous admixture was significantly correlated with DSS with the treatment time taken as covariate (p < 0.0001; r = 0.65). No differences were found for any VCap parameters. CONCLUSIONS AND CLINICAL RELEVANCE: In dorsally recumbent anaesthetized horses, CPAP of 8 cmH2O results in redistribution of ventilation towards the dependent lung regions, thereby improving ventilation-perfusion matching. This improvement was not associated with an increase in dead space indicative for a lack in distension of the airways or impairment of alveolar perfusion.

Regional distribution of ventilation in horses in dorsal recumbency during spontaneous and mechanical ventilation assessed by electrical impedance tomography: a case series.

OBJECTIVE: To evaluate the regional distribution of ventilation in horses during spontaneous breathing and controlled mechanical ventilation (CMV) using electrical impedance tomography (EIT). STUDY DESIGN: Prospective, experimental case series. ANIMALS: Four anaesthetized experimental horses. METHODS: Horses were anaesthetized with isoflurane in an oxygen-air mixture and medetomidine continuous rate infusion, placed in dorsal recumbency with an EIT belt around the thorax, and allowed to breathe spontaneously until PaCO2 reached 13.3 kPa (100 mmHg), when volume CMV was started. For each horse, the EIT signal was recorded for at least 2 minutes immediately before (T1), and at 30 (n = 3) or 60 (n = 1) minutes after the start of CMV (T2). The centre of ventilation (CoV), dependent silent spaces (DSS) (likely to represent atelectatic lung areas), non-dependent silent spaces (NSS) (likely to represent lung areas with low ventilation) and total ventilated area (TVA) were evaluated. Cardiac output (CO) was measured and venous admixture and oxygen delivery (DO2) were calculated at T1 and T2. Data are presented as median and range. RESULTS: After the initiation of CMV, the CoV moved ventrally towards the non-dependent lung by 10% [from 57.4% (49.6-60.2%) to 48.3% (41.9-54.4%)]. DSS increased [from 4.1% (0.2-13.9%) to 18.7% (7.5-27.5%)], while NSS [21.7% (9.4-29.2%) to 9.9% (1.0-20.7%)] and TVA [920 (699-1051) to 837 (662-961) pixels] decreased. CO, venous admixture and DO2 also decreased. CONCLUSIONS AND CLINICAL RELEVANCE: In spontaneously breathing anaesthetized horses in dorsal recumbency, ventilation was essentially centred within the dependent dorsal lung regions and moved towards non-dependent ventral regions as soon as CMV was started. This shows a major lack of ventilation in the dependent lung, which may be indicative of atelectasis.

Horses Auto-Recruit Their Lungs by Inspiratory Breath Holding Following Recovery from General Anaesthesia.

This study evaluated the breathing pattern and distribution of ventilation in horses prior to and following recovery from general anaesthesia using electrical impedance tomography (EIT). Six horses were anaesthetised for 6 hours in dorsal recumbency. Arterial blood gas and EIT measurements were performed 24 hours before (baseline) and 1, 2, 3, 4, 5 and 6 hours after horses stood following anaesthesia. At each time point 4 representative spontaneous breaths were analysed. The percentage of the total breath length during which impedance remained greater than 50% of the maximum inspiratory impedance change (breath holding), the fraction of total tidal ventilation within each of four stacked regions of interest (ROI) (distribution of ventilation) and the filling time and inflation period of seven ROI evenly distributed over the dorso-ventral height of the lungs were calculated. Mixed effects multi-linear regression and linear regression were used and significance was set at p<0.05. All horses demonstrated inspiratory breath holding until 5 hours after standing. No change from baseline was seen for the distribution of ventilation during inspiration. Filling time and inflation period were more rapid and shorter in ventral and slower and longer in most dorsal ROI compared to baseline, respectively. In a mixed effects multi-linear regression, breath holding was significantly correlated with PaCO2 in both the univariate and multivariate regression. Following recovery from anaesthesia, horses showed inspiratory breath holding during which gas redistributed from ventral into dorsal regions of the lungs. This suggests auto-recruitment of lung tissue which would have been dependent and likely atelectic during anaesthesia.

Continuous positive airway pressure (CPAP) decreases pulmonary shunt in anaesthetized horses.

OBJECTIVE: To evaluate the effects of continuous positive airway pressure (CPAP) on intrapulmonary shunt, cardiac output and oxygen delivery in horses subjected to a 6 hour period of general anaesthesia. STUDY DESIGN: Randomized, experimental, crossover study. ANIMALS: Ten healthy adult horses. METHODS: Following medetomidine, diazepam and ketamine administration, orotracheal intubation was performed and horses positioned in dorsal recumbency. Anaesthesia was maintained with isoflurane carried in an oxygen and air mix (FiO2 0.5) combined with a medetomidine infusion. Horses were anaesthetized twice and either CPAP (8 cmH2 O) or physiologic airway pressure (NO CPAP) was applied to the lungs for 6 hours; the order of treatments was randomly assigned. Following induction of anaesthesia, cardiovascular and respiratory variables (including arterial blood gas analysis) were recorded every 30 minutes, cardiac output was measured every 60 minutes using the lithium dilution technique and oxygen delivery calculated. If PaCO2 exceeded 100 mmHg (13.3 kPa), controlled ventilation was initiated and horses excluded from further data collection. Groups were compared using a general linear model. RESULTS: Data from eight horses were analysed. PaO2 was 15-56 mmHg (2.00-7.45 kPa) higher (p < 0.001) and shunt fraction 6-14% lower (p < 0.001) in the CPAP group. No differences were seen for cardiac output and oxygen delivery. The lack of difference in oxygen delivery was attributed to lower haemoglobin levels in the CPAP group than in the NO CPAP group. CONCLUSIONS AND CLINICAL RELEVANCE: CPAP of 8 cmH2 O can be used in dorsally recumbent horses to decrease pulmonary shunt fraction without causing a decrease in cardiac output during longterm anaesthesia.

Perioperative trends in plasma colloid osmotic pressure in horses undergoing surgery.

OBJECTIVE: To compare perioperative trends in plasma colloid osmotic pressure (COP) between horses undergoing orthopedic and colic surgery. DESIGN: Prospective clinical study September 2009-January 2011. SETTING: Veterinary university teaching hospital. ANIMALS: Thirty-three healthy, client-owned horses presenting for orthopedic surgery (non-GI) and 85 client-owned horses presenting for emergency exploratory celiotomy (GI, gastrointestinal). INTERVENTIONS: None. MEASUREMENTS: Data relating to the horse's parameters on presentation, surgical lesion, post-operative management and survival were extracted from computerized clinical records. Heparinized blood samples were taken on presentation (PreOp, pre-operative), on recovery from anesthesia (T0), at 12 (T12) and 24 (T24) hours post recovery. COP was measured within 4 hours of collection. RESULTS: There was no significant difference in PreOp or T0 COP between groups. Both groups had a significant decrease in COP during anesthesia. When compared to their respective pre-operative values, horses in the non-GI group had significantly increased COP at T12, whereas those in the GI group had significantly reduced COP. This trend was continued at T24. Horses in the GI group placed on intravenous crystalloid isotonic fluids post-operatively had a significantly lower COP at T12 and T24. Horses in the GI group that did not survive had significantly lower post-operative COP values at T24. CONCLUSIONS: Horses undergoing exploratory celiotomy had significantly lower COP post-operatively than those horses undergoing orthopedic surgery. This difference was more marked in those horses receiving isotonic crystalloid intravenous fluid therapy post-operatively and in those that did not survive to discharge. In the non-GI group an increase in COP post-operatively was common.

Preliminary investigation comparing a detomidine continuous rate infusion combined with either morphine or buprenorphine for standing sedation in horses.

OBJECTIVE: To compare sedative and analgesic properties of buprenorphine or morphine for standing procedures combined with a detomidine continuous rate infusion (CRI). STUDY DESIGN: Blinded, prospective, randomized clinical pilot study. ANIMALS: Ten horses presented for dental or sinus procedures. METHODS: Horses received 0.02 mg kg(-1) acepromazine intravenously (IV), followed 30 minutes later by detomidine 10 µg kg(-1) IV. Five minutes later, buprenorphine 0.01 mg kg(-1) (n = 6) or morphine 0.1 mg kg(-1) (n = 4) was administered IV. Detomidine was administered by CRI (0.2 µg kg(-1) minute(-1)) and adjusted to maintain appropriate sedation. Heart rate, respiratory frequency, gastrointestinal motility and rectal temperature were measured; pain, ataxia and sedation were scored. Sedation, pain scores and ataxia scores were analysed using a mixed linear model. Detomidine dose and procedure success scores were compared using Wilcoxon's rank sum test. Complications between groups were analysed using Fisher's exact test. RESULTS: Two horses had incomplete data. Weights and ages were not different between groups (p = 0.15 and p = 0.42, respectively). The dose rate for detomidine was not different between groups (0.33 ± 0.02 µg kg(-1) minute(-1) in the buprenorphine group and 0.33 ± 0.05 µg kg(-1) minute(-1), in the morphine group p = 0.89). Intraoperative visual analogue scale scores were greater after buprenorphine than morphine (mean ± SD, buprenorphine 48 ± 4, morphine 40 ± 5, p = 0.0497). Procedure duration was not different between groups (buprenorphine 142 ± 33, morphine 140 ± 12 minutes). All horses treated with buprenorphine experienced complications compared with none in the morphine group (p = 0.0286). CONCLUSIONS AND CLINICAL RELEVANCE: At the doses used, buprenorphine produced greater sedation but more post-operative complications than morphine. However, Type I or Type II errors cannot be excluded and larger studies are required to confirm these findings.

Comparison of sedation scores and propofol induction doses in dogs after intramuscular premedication with butorphanol and either dexmedetomidine or medetomidine.

OBJECTIVE: To compare sedation scores and propofol induction doses in dogs receiving either dexmedetomidine or medetomidine, both with butorphanol intramuscularly (IM) prior to general anaesthesia. STUDY DESIGN: Prospective, 'blinded', randomized, clinical study. ANIMALS: Fifty client-owned dogs scheduled for elective diagnostic imaging procedures. METHODS: Dogs were allocated to receive butorphanol 0.1 mg kg(-1) with either medetomidine (group M) 0.01 mg kg(-1) or dexmedetomidine (group D) 0.005 mg kg(-1) IM. Sedation was scored before and 20 minutes after pre-anaesthetic medication using a composite simple descriptive sedation score giving a score of 0 to 15 (0 = no sedation; 15 = profound sedation). Forty-five minutes after pre-anaesthetic medication, propofol was administered in increments of 0.5 mg kg(-1) over 15 seconds until tracheal intubation was possible. The time required to check intubation conditions between each propofol aliquot was 15 seconds. Total propofol dose required to perform tracheal intubation and the number of dogs achieving a clinically desired sedation score of ≥9/15 was recorded in each group. Sedation score and propofol dose were compared using the Mann-Whitney U-test. Results are reported as median (range). Statistical significance was set at p < 0.05. RESULTS: The sedation score 20 minutes after pre-anaesthetic medication was significantly higher in group M [11 (2-14)] than in group D [7 (0-14)]. There was no significant difference between propofol dose requirements in group M [1.5 (1-2.5) mg kg(-1)] or D at [1.5 (1-3) mg kg(-1)]. Significantly more dogs in group M achieved a sedation score of ≥9/15 than in group D. CONCLUSIONS AND CLINICAL RELEVANCE: Combined IM with butorphanol, medetomidine 0.01 mg kg(-1) produced effective sedation more frequently than dexmedetomidine 0.005 mg kg(-1) in dogs undergoing sedation prior to anaesthesia for elective procedures but this did not affect the propofol dose required for induction of anaesthesia significantly.

Early experience with continuous positive airway pressure (CPAP) in 5 horses -- a case series.

This case series is the first report of the use of CPAP (continuous positive airway pressure) ventilation in adult horses. Two horses and 3 ponies anesthetized for orthopedic procedures in lateral recumbency received 10 cm H(2)O CPAP. During anesthesia, arterial oxygen partial pressure tended to increase and arterial carbon dioxide pressure tended to increase despite increased minute ventilation index. The measured cardiovascular parameters were within physiologic limits.

Comparison of invasive and non-invasive blood pressure monitoring during clinical anaesthesia in dogs.

Monitoring blood pressure during anaesthesia is widely recommended in man and animals. The accuracy of any device used to measure blood pressure is an important consideration when selecting monitoring equipment, the ANSI/AAMI SP10 standard is widely cited in this respect in recent veterinary publications. Blood pressure was monitored using invasive and non-invasive techniques during clinical anaesthesia in 19 dogs. The results were compared using Bland-Altman analysis. The bias (and limits of agreement) between invasive and non-invasive measurement was 7.1 mmHg (+/-34.7) for systolic blood pressure, -1.8 mmHg (+/-27.4) for mean blood pressure and 6.9 mmHg (+/-27.5) for diastolic blood pressure. In a clinical setting the bias between invasive and non-invasive measurement techniques was similar or smaller than laboratory reports, however the limits of agreement were considerably wider suggesting that care should be exercised when interpreting NIBP values.