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To evaluate the agreement between measurements of invasive blood pressure (IBP) and oscillometric blood pressure from the tongue (OBPton) using a multiparameter monitor. Unblinded, prospective, experimental study. A total of 12 female Large White crossbreed pigs. Pigs undergoing experimental procedures that required arterial cannula placement were recruited. A blood pressure cuff with the closest width to 40% of the circumference of the tongue was placed rostral to the lingual frenulum. Systolic, mean and diastolic IBP and OBPton were measured simultaneously at 5 minute intervals. Agreement between paired measurements was examined using Bland–Altman analysis. Mean bias, precision (standard deviation of mean bias), 95% limits of agreement, correlation coefficients and percentage of measurements within 10 and 20 mmHg of IBP were calculated. The total numbers of paired measurements recorded were 124, 126 and 124 for systolic, mean and diastolic blood pressures, respectively. The mean bias, precision and 95% limits of agreement for systolic OBPton were 11.5, 11.5 (–11.1 to 34.2), for mean OBPton 5.6, 5.7 (–5.7 to 16.8) and for diastolic OBPton 7.6, 10.1 (–12.1 to 27.4) mmHg. Correlation coefficients were greater than 0.9 for mean OBPton only. More than 50% of measurements were within 10 mmHg of IBP and 80% of measurements were within 20 mmHg of IBP for mean and diastolic OBPton only. The tongue as a cuff site for oscillometric blood pressure measurement is a useful site for measuring mean arterial, but not systolic or diastolic blood pressure in anaesthetized Large White crossbreed pigs. This technique fulfils the American College of Veterinary Internal Medicine criteria for measuring mean arterial pressure but not systolic or diastolic arterial pressure. [ABSTRACT FROM AUTHOR]

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. Prospective observational study. 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. 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. 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. [ABSTRACT FROM AUTHOR]

To investigate the analgesic effect of epidural morphine after surgical extrahepatic portosystemic shunt (EHPSS) attenuation. Randomized clinical trial. A total of 20 dogs with a congenital EHPSS. 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. 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. Epidural morphine reduced the requirement for postoperative analgesia in this study population. [ABSTRACT FROM AUTHOR]

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 cmH2O) 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 cmH2O can be used in dorsally recumbent horses to decrease pulmonary shunt fraction without causing a decrease in cardiac output during longterm anaesthesia. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

To evaluate the accuracy with which veterinary anaesthetists and nurses of different experience draw up small volumes of liquid. Prospective blinded randomized study. 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. 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. 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. Prospective clinical cohort study. A total of 75 healthy client-owned dogs undergoing GA for elective tibial plateau levelling osteotomy. 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. 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. 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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), nondependent 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. [ABSTRACT FROM AUTHOR]