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Summary: Background: The use of pulse oximetry in horses is limited due to inadequate readings with conventional transmission sensor probes. Objectives: The objectives of this study were to 1) develop an improved sensor design for horses to be used at an appropriate anatomical site, and 2) evaluate this design in an experimental study. Study design: In vivo experiment. Methods: A new sensor design for reflectance pulse oximetry at the buccal mucosa was developed. A conventional Nonin 2000SL sensor for transmission pulse oximetry was included into this design. Three different prototypes (N1, N2a, N2b) were constructed and used with the Nonin 2500A Vet pulse oximetry monitor. Thirteen anaesthetised warmblood horses were included into a desaturation protocol (100–70% SaO2). SpO2 and pulse frequency values were recorded, using SaO2 calculated from blood gas analysis and invasive pulse frequency measurements as reference methods. Bias and precision were evaluated by calculations of the root mean square deviation (Arms). The agreement of the methods was tested with Bland‐Altman analysis. Results: The quality of the pulse frequency readings determined the quality of the SpO2‐readings. Good pulse signal strength resulted in a SpO2‐accuracy comparable to that of the original sensor (Nonin 2000SL: Arms = 3%; N1: Arms = 3.60%; N2b: Arms = 3.46%). Especially at heart rates ≤30 bpm, pulse rate readings that were about twice as high as the reference value occurred. Their exclusion from the dataset resulted in a pulse rate accuracy similar to that of the original sensor. Bland‐Altman plots showed limits of agreement typical of pulse oximeters. Main limitations: The pulse frequency accuracy requires further improvement. The usability in clinical cases needs to be tested. Conclusions: The new sensor design has been shown to be suitable for buccal pulse oximetry in horses. [ABSTRACT FROM AUTHOR]

Reasons for performing study High airway pressures, necessary to keep equine lungs open, can have a detrimental impact on central and peripheral perfusion. Objective The aim of this study was to assess the effects of stepwise increasing airway pressure recruitment on central and intestinal perfusion and oxygenation during isoflurane anaesthesia in horses. Study design In vivo experimental study. Methods Ten anaesthetised horses were ventilated using intermittent positive pressure ventilation immediately after induction. After 90 min, end-expiratory pressure ( PEEP) was increased by steps of 5 cmH2O every 10 min up to a PEEP of 30 cmH2O and decreased back to zero maintaining a constant airway pressure difference of 20 cmH2O. Mean arterial blood pressure ( MAP), heart rate, central venous pressure, pulmonary artery pressure, expiratory isoflurane concentration and cardiac output (thermodilution method) were measured. Cardiac index ( CI) was calculated. Arterial blood gases were taken to measure arterial partial oxygen pressure (PaO2) and calculate arterial oxygen saturation (SaO2). Intestinal microperfusion and oxygenation were measured by laser Doppler flowmetry and white-light spectrophotometry. After ventral median laparotomy, a probe was placed on the stomach, jejunum and pelvic flexion of the colon. An ANOVA for repeated measurements and Tukey's post hoc test were used for statistical analysis (α = 5%). Results Recruitment of the lungs resulted in a significant increase in PaO2 from 201 ± 58 mmHg (baseline) to a maximum of 495 ± 75 mmHg. The CI and MAP decreased continuously with increasing airway pressures. When CI and MAP were 37 ± 9 ml/kg/min and 52 ± 8 mmHg (at PEEP of 25 cmH2O), respectively, a sudden decrease in intestinal perfusion followed by a delayed decrease in oxygenation occurred. Conclusions There was linear correlation between airway pressures and CI and MAP but not between central and gastrointestinal perfusion. Despite improvement of arterial oxygenation the decrease in CI and, therefore, in oxygen delivery PEEP resulted in a decrease in gastrointestinal oxygenation. [ABSTRACT FROM AUTHOR]

The article compares the disposition of dexmedetomidine and levomedetomidine in small ruminants during sevoflurance anesthesia. Six adult sheep and adult goats were used for the study. Anesthesia was induced with sevoflurane in oxygen delivered via a mask until orotracheal intubation was possible. Findings show that distribution and elimination kinetics of both drugs during general anesthesia are very rapid in both animals. In both, species elimination of levomedetomidine seems to be more effective than of dexmedetomidine.

The objective of the present study was to determine the potency of dexmedetomidine in relation to medetomidine in sheep undergoing orthopaedic surgery by comparing the anaesthetic requirements and cardiovascular changes at a dose relationship that represented equipotency in vitro. Twenty-four non-pregnant, female sheep were used. The study was carried out as a blind, randomized, experimental trial. Group 1 received 5 μg/kg bodyweight (BW) dexmedetomidine and group 2 received 10 μg/kg BW medetomidine intravenously 5 min prior to induction of anaesthesia. Anaesthesia was induced with ketamine (2.0 mg/kg BW intravenously) and maintained with isoflurane in 100 % oxygen. End expired anaesthetic concentration (FÈIso), end expired carbon dioxide concentration (FÈCO2), respiratory frequency (fR), direct arterial blood pressures, heart rates (HR) and arterial blood gases were monitored. Data were averaged over time and tested for differences between groups by independent t-tests, and analysis of variance for repeated measures. Average FÈIso concentrations required to maintain a surgical plane of anaesthesia were not different between groups (1: 1.02 ± 0.04%; 2: 0.99 ± 0.07%). There was no difference in HR, arterial blood pressures, fR, FÈCO2 and arterial blood gases between groups. Average mean PaO2 were 279.54 ± 113.37 mmHg and 220.21 ± 102.15 mmHg with individual minimum values of 27.2 mmHg and 58.5 mmHg in groups 1 and 2, respectively. In conclusion, intravenous dexmedetomidine at 5 μg/kg BW and medetomidine at 10 μg/kg BW have the same effects on isoflurane requirements and cardiopulmonary parameters in sheep, indicating an equipotent dose relationship. Both preparations induced moderate to severe hypoxaemia in individual sheep. [ABSTRACT FROM AUTHOR]

Examines the use of modern gas analysers in closed-system anaesthesia. Composition of gas in the circuit; Importance to evaluate potential room air contamination of breathing circuit gases; Administration of epidural anaesthetic.

The aim of this study was to assess agreement and repeatability of four ultrasound methods for measuring stroke volume (SV) and cardiac output (CO) in cats. Measurement of SV and CO was performed by the Teichholz method, the Simpson's method (SM), the area length method (ALM) and a volumetric flow method across the aorta (Trace method). For each method, the coefficient of variation (CV) was calculated and agreement was determined by Bland-Altman analysis. The CV was acceptable (<20%) for all parameters, except for SV and CO obtained by SM (28.8% and 22.4%, respectively) and ALM (21.6% and 22.6%, respectively). Narrow limits of agreement were observed between both planimetric methods (SM and ALM). The Trace method was the most repeatable, followed by the Teichholz method. Despite excellent inter-method agreement, neither of the planimetric methods produced results with adequate repeatability. As the Teichholz and Trace methods were acceptably repeatable, and probably gave the most representative values, they appear to be the most useful methods for the measurement of SV and CO in cats. Further investigations are needed to compare the echocardiographic methods described here with a standard technique such as thermodilution. [ABSTRACT FROM AUTHOR]

The goal of this study was to determine the effects of plasmapheresis on the behaviour, general condition, haematological, biochemical and coagulation variables of donor horses for 32 days following the procedure. Twenty millilitres of plasma/kg body weight were collected via plasmapheresis in six clinically healthy horses. The general behaviour and condition of the horses was not affected by the procedure. During plasmapheresis, there was a mild increase in the haematocrit, haemoglobin concentration and total erythrocyte and leucocyte counts (P < 0.01). The mean concentrations of total protein and albumin decreased significantly (P < 0.01) and total protein did not normalise for about three weeks. Several other biochemical variables also decreased significantly during plasmapheresis, but mostly remained within reference ranges. After plasmapheresis, the mean value of the activated partial thromboplastin time and the thrombin time were mildly but significantly increased (P < 0.01), and the mean activities of factor V, factor VIII and antithrombin decreased significantly (P < 0.01), although all coagulation values remained within reference ranges. Our results indicate that, in horses, the collection of 20 mL of plasma/kg body weight via plasmapheresis results in mild changes in several haematological, biochemical and coagulation variables, although these were of no clinical relevance for the donors. [ABSTRACT FROM AUTHOR]

There are few investigations relating anti-nociception to plasma concentrations of fentanyl in horses. The study objective was to evaluate analgesic efficacy and duration in horses and determine the minimum anti-nociceptive plasma concentrations. Eight horses were treated with saline (P) and fentanyl (F 2.5 =2.5μg/kg; F 5 =5μg/kg; F 10 =10μg/kg) given IV over 5min, with a wash-out period of 10 days. To evaluate thermal (°C) and mechanical (N) nociceptive threshold single stimulations were applied prior to (baseline) and 10, 30, 60, 90, 120, 180, 240, 300, 360, 420, 540min and 22.5h after treatment. Plasma fentanyl concentrations were measured at specific time points. Locomotor activity, heart rate, respiratory rate and gastrointestinal sounds were recorded. Two-way repeated measures ANOVA and pairwise comparisons were used for data analysis (P<0.05). With treatment F 10 , there was a significant increase in thermal threshold above baseline (47.2ö4.1°C) at t 10 (53.7ö4.2°C) and t 30 (52.1ö5.6°C), whereas mechanical threshold increased considerably above baseline (3.7ö1.3N) only at t 10 (6.6ö3.6N). Estimated mean minimum anti-nociceptive plasma concentration determined by thermal stimulation was 6.1-6.8ng/mL. Dose-dependent increased locomotion occurred, but no significant changes in heart rate, respiratory rate and gastrointestinal sounds were observed. Fentanyl IV at 10μg/kg produced anti-nociception for 10-30min and fentanyl plasma concentrations of ≥6.1-6.8ng/mL appear necessary to induce thermal anti-nociception. Dose-dependent increased locomotion was the main side effect observed., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The aim of this study was to evaluate the influence of two sedation protocols on transcranial magnetic motor evoked potentials (TMMEPs) after transcranial magnetic stimulation in medium sized dogs. Onset latencies and peak-to-peak amplitudes, elicited in the extensor carpi radialis and cranial tibial muscles, were analysed in 10 healthy Beagles that received either acepromazine or dexmedetomidine in combination with levomethadone/fenpipramide, in a crossover design. Similar TMMEP recordings could be made using both sedation protocols at 80-90% stimulation intensity; however, there were significantly shorter onset latencies with the acepromazine-levomethadone/fenpipramide protocol at 100% stimulation intensity. Reference values were established and it was concluded that both drug combinations are feasible for measuring TMMEPs in medium sized dogs., (Copyright © 2016 Elsevier Ltd. All rights reserved.)