Accuracy and trending capability of haemoglobin measurement by noninvasive pulse co-oximetry in anaesthetized horses.

OBJECTIVE: To assess the accuracy and trending capability of continuous measurement of haemoglobin concentration [Hb], haemoglobin oxygen saturation (SaO2) and oxygen content (CaO2) measured by the Masimo Radical-7 pulse co-oximeter in horses undergoing inhalational anaesthesia. STUDY DESIGN: Prospective observational clinical study. ANIMALS: A group of 23 anaesthetized adult horses. METHODS: In 23 healthy adult horses undergoing elective surgical procedures, paired measurements of pulse co-oximetry-based haemoglobin concentration (SpHb), SaO2 (SpO2), and CaO2 (SpOC) and simultaneous arterial blood samples were collected at multiple time points throughout anaesthesia. The arterial samples were analysed by a laboratory co-oximeter for total haemoglobin (tHb), SaO2 and manually calculated CaO2. Bland-Altman plots, linear regression analysis, error grid analysis, four-quadrant plot and Critchley polar plot were used to assess the accuracy and trending capability of the pulse co-oximeter. Data are presented as mean differences and 95% limits of agreement (LoA). RESULTS: In 101 data pairs analysed, the pulse co-oximeter slightly underestimated tHb (bias 0.06 g dL-1; LoA -1.0 to 1.2 g dL-1), SaO2 (bias 1.4%; LoA -2.0% to 4.8%), and CaO2 (bias 0.3 mL dL-1; LoA -2.1 to 2.7 mL dL-1). Zone A of the error grid encompassed 99% of data pairs for SpHb. Perfusion index (PI) ≥ 1% was recorded in 58/101 and PI < 1% in 43/101. The concordance rate for consecutive changes in SpHb and tHb with PI ≥ 1% and < 1% was 80% and 91% with four-quadrant plot, and 45.8% and 66.6% with Critchley polar plot. CONCLUSIONS: Pulse co-oximetry has acceptable accuracy for the values measured, even with low PI, whereas its trending ability requires further investigation in those horses with a higher [Hb] variation during anaesthesia.

Near-infrared imaging and optical coherence tomography for intraoperative visualization of tumors.

Surgical excision is the foundation of treatment for early-stage solid tumors in man and companion animals. Complete excision with appropriate margins of surrounding tumor-free tissue is crucial to survival. Intraoperative imaging allows real-time visualization of tumors, assessment of surgical margins, and, potentially, lymph nodes and satellite metastatic lesions, allowing surgeons to perform complete tumor resections while sparing surrounding vital anatomic structures. This Review will focus on the use of near-infrared imaging and optical coherence tomography for intraoperative tumor visualization.

Appraisal of the 'penumbra effect' using lingual pulse oximetry in anaesthetized dogs and cats.

OBJECTIVE: Factors described as contributors to the 'penumbra effect' in relation to pulse oximetry include optical shunting, circulatory anastomoses and probe parallelity. This study aimed to clarify the main underlying mechanism involved. STUDY DESIGN: Prospective clinical trial. ANIMALS: A total of 30 dogs and 15 cats (client-owned). METHODS: In anaesthetized dogs and cats, a pulse oximeter probe was placed on the tongue to measure haemoglobin oxygen saturation (SpO2) and perfusion index. In 15 dogs, the probe was positioned at the root (baseline) of the tongue, then at 0.5 and 1 cm rostral to it, to investigate the effect of circulatory anastomoses on SpO2 values. In cats (which do not have lingual arteriovenous anastomoses), the probe was positioned at the root and apex of the tongue. To assess the effect of probe parallelity on SpO2 values in dogs, two lines were drawn parallel to the planes of the light-emitting diode and the detector surfaces and the intersection angle calculated using ImageMeter Pro, Google Play. In a further 15 dogs, the probe was placed at the tongue edge (0% optical shunt), with 50% optical shunt, then with the 50% optical shunt shielded. Data were analysed using Friedman's test, Student t test and Pearson's correlation coefficient (p < 0.05). RESULTS: In dogs, SpO2 values were significantly higher at 1.0 cm than at baseline (p < 0.0001). In cats, there were no significant differences in SpO2 values at each location. There was no significant difference in SpO2 between 0% and 50% optical shunt in dogs. SpO2 had a moderate negative correlation with tongue thickness and negligible correlation with intersection angle. CONCLUSIONS AND CLINICAL RELEVANCE: Circulatory anastomoses are probably responsible for observed changes in SpO2 as the probe is placed towards an extremity, rather than optical shunting or probe parallelity.

Clinical monitoring of cardiac output assessed by transoesophageal echocardiography in anaesthetised dogs: a comparison with the thermodilution technique.

BACKGROUND: Cardiac output (CO) is an important haemodynamic parameter to monitor in patients during surgery. However, the majority of the techniques for measuring CO have a limited application in veterinary practice due to their invasive approach and associated complexity and risks. Transoesophageal echocardiography (TEE) is a technique used to monitor cardiac function in human patients during surgical procedures and allows CO to be measured non-invasively. This prospective clinical study aimed to compare the transoesophageal echocardiography using a transgastric view of the left ventricular outflow tract (LVOT) and the thermodilution (TD) technique for the assessment of CO during mean arterial pressure of 65-80 mmHg (normotension) and <65 mmHg (hypotension) in dogs undergoing elective surgery. Eight dogs were pre-medicated with acepromazine (0.05 mg/kg, IM), tramadol (4 mg/kg, IM) and atropine (0.03 mg/kg, IM), followed by anaesthetic induction with propofol (3-5 mg/kg IV) and maintenance with isoflurane associated with a continuous infusion rate of fentanyl (bolus of 3 µg/kg followed by 0.3 µg/kg/min). The CO was measured by TEE (COTEE) and TD (COTD) at the end of expiration during normotension and hypotension (induced by isoflurane). RESULTS: There was a strong positive correlation between COTEE and COTD ​​(r = 0.925; P < 0.0001). The bias between COTD and COTEE was 0.14 ± 0.29 L/min (limits of agreement, -0.44 to 0.72 L/min). The percentage error of CO measured by the two methods was 12.32%. In addition, a strong positive correlation was found between COTEE and COTD during normotension (r = 0.995; P < 0.0001) and hypotension (r = 0.78; P = 0.0223). CONCLUSIONS: The results of this study indicated that the transgastric view of the LVOT by TEE was a minimally invasive alternative to clinically monitoring CO in dogs during anaesthesia. However, during hypotension, the CO obtained by TEE was less reliable, although still acceptable.

Basics of monitoring equipment.

Monitoring equipment has become reliable and affordable for use in general veterinary practice. This article provides a guide to technology, troubleshooting, and obtaining quality data using 4 non-invasive techniques that are commonly used in practice. Pulse oximetry estimates oxygen saturation of hemoglobin in arterial blood, capnography measures the carbon dioxide content of inspired and expired gas, and either Doppler shift detection or oscillometry can be used to measure blood pressure. These useful non-invasive techniques all rely on adequate perfusion of the tissues for optimum function.

Éléments fondamentaux de l'équipement de monitorage. L'équipement de monitorage est devenu fiable et abordable pour utilisation dans la pratique vétérinaire générale. Le présent article présente un guide sur la technologie, le diagnostic de panne et l'obtention de données de qualité en utilisant quatre techniques non invasives qui sont communément utilisées en pratique. L'oxymétrie pulsée estime la saturation en oxygène de l'hémoglobine dans le sang artériel, la capnographie mesure le contenu en gaz carbonique du gaz inspiré et expiré et la détection du déplacement Doppler ou l'oscillométrie peut être utilisée pour mesurer la pression artérielle. Ces techniques non invasives s'appuient toutes sur une perfusion adéquate des tissus pour une fonction optimale.(Traduit par Isabelle Vallières).

Comparison of invasive and noninvasive blood pressure measurements in anaesthetized horses using the Surgivet V9203.

OBJECTIVES: To determine the bias and precision of noninvasive versus invasive blood pressure measurements obtained using the Surgivet V9203 in anaesthetized horses; to compare these with the current American College of Veterinary Internal Medicine Hypertension Consensus Panel (AHCP) and Veterinary Blood Pressure Society (VBPS) recommendations; and to investigate whether noninvasive blood pressure monitoring could be a clinically useful alternative to invasive blood pressure monitoring in anaesthetized horses. STUDY DESIGN: Prospective clinical study in a university teaching hospital. ANIMALS: Forty-three horses with an average weight of 485 ± 90 kg and a mean age of 103.4 ± 57.6 months. METHODS: Arterial blood pressure (BP) was measured noninvasively (NIBP) via a cuff placed over either the ventral coccygeal artery or the metacarpal artery, and invasively (IBP) via a catheter in either the facial artery or the metatarsal artery. A total of 143 paired readings were obtained. Comparison of measurements was carried out using the Bland-Altman method. Analysis was performed using all the data, and these data were subdivided according to the position of the horse and the magnitude of the pressure measurement. To determine the accuracy of the noninvasive measurements, the calculated precision and bias were compared with AHCP and VBPS guidelines. RESULTS: For all categories, NIBP measurements were generally lower than IBP measurements. For pooled data, the bias and precision for systolic arterial pressure (SAP) were 6.8 and 11.9 mmHg; for mean arterial pressure (MAP) the values were 1.9 and 10.0 mmHg; and for diastolic arterial pressure (DAP) they were 5.7 and 10.8 mmHg. The bias and precision for MAP and DAP measurements were within the recommended guidelines defined by the AHCP and VBPS. CONCLUSIONS AND CLINICAL RELEVANCE: These results suggests that systolic, mean and diastolic NIBP measured using the Surgivet V9203 are a clinically acceptable alternative to IBP measurements in anaesthetized horses undergoing routine elective surgeries.

The Edwards Acumen IQ system using peripheral arterial catheter-based waveforms to estimate cardiac output is not accurate as compared to thermodilution in dogs.

OBJECTIVE: To assess the agreement between cardiac output (CO) estimated via evaluation of the arterial pressure waveform by a novel monitoring system (Edwards Acumen IQ sensor and HemoSphere Advanced Monitor Platform [HS-IQ]; Edwards LifeSciences) and measured by thermodilution (TD) in anesthetized, normovolemic, and hypovolemic dogs. To assess the agreement between the HS-IQ CO measurements in the radial artery and dorsal metatarsal artery. ANIMALS: 8 purpose-bred Beagles. METHODS: Dogs were placed under general anesthesia. CO was measured via TD and via the HS-IQ at radial and dorsal metatarsal arterial catheters. CO measurements were obtained at 4 time points including normovolemic and multiple hypovolemic states. Paired measurements of CO were evaluated via the method of Bland and Altman with acceptable limits of agreement (LOA) defined as < 30%. RESULTS: A total of 24 (dorsal metatarsal) and 21 (radial) paired measurements were collected in 8 dogs. The overall bias (CI) for comparison of TD to radial arterial HS-IQ CO measurements was -0.09 L/min. LOA and proportional LOA were -2.66 to 2.49 L/min and -140.72% to 104.94%. The overall bias (CI) for comparison of TD to dorsal metatarsal arterial HS-IQ CO measurements was -0.26 L/min. LOA and proportional LOA were -2.76 to 2.24 L/min and -135.96% to 93.25%. The overall proportional error for radial arterial was -17.9% and for dorsal metatarsal was -21.4%. CLINICAL RELEVANCE: CO measurements with the HS-IQ were easy to obtain but did not produce results within a clinically acceptable range for either measurement site, with a very wide LOA. The CO estimations from the HS-IQ are not appropriate for clinical use at this time.

Cardiac output monitoring in horses.

Cardiac output (CO) is the volume of blood pumped out by the heart in 1 minute. Monitoring of CO can guide therapy and improve clinical outcome in critically ill patients and during anesthesia. Although there is increasing research into clinically useful methods of monitoring CO in equine patients, there are limitations to the available methods. There are 4 basic methods of measuring CO: (1) indicator methods, (2) a derivation of the Fick principle, (3) arterial pulse wave analysis, and (4) imaging diagnostic techniques. This article discusses the importance of CO, available technology, and challenges of monitoring CO in equine medicine.

Evaluation of a minimally invasive non-calibrated pulse contour cardiac output monitor (FloTrac/Vigileo) in anaesthetized dogs.

OBJECTIVE: To evaluate the accuracy of a new cardiac output monitor (FloTrac/Vigileo), originally designed for humans, in dogs. This pulse contour cardiac output monitoring system cannot be calibrated and measures cardiac output (Q̇t) from a standard arterial catheter. STUDY DESIGN: Prospective experimental trial. ANIMALS: Eight adult Beagle dogs weighing 13.1 (9.8-17.1) kg [median (range)]. METHODS: Anaesthesia in the dogs was maintained using isoflurane. A pulmonary artery catheter and a metatarsal arterial catheter (22 gauge) were placed. Cardiac output was measured simultaneously 331 times by thermodilution and FloTrac technique. A broad spectrum of Q̇t measurements was achieved through alterations of isoflurane concentration, administration of propofol boluses and dobutamine infusions. Agreement between the methods was quantified with Bland Altman analysis and disagreement was assessed with linear mixed models. Results Median (10th and 90th percentile) cardiac output as measured with thermodilution was 2.54 (1.47 and 5.15) L minute(-1) and as measured with FloTrac 8.6 (3.9 and 17.3) L minute(-1) . FloTrac measurements were consistently higher with a mean bias of 7 L minute(-1) and limits of agreement of -3.15 to 17.17 L minute(-1) . Difference between the methods was most pronounced in high Q̇t measurements. Linear mixed models showed an estimated difference between the two methods of 8.05 (standard error 1.18) L minute(-1) and a significant interaction between mean arterial pressure and method. Standard deviation (4.45 higher) with the FloTrac method compared to thermodilution was increased. CONCLUSION: Compared to thermodilution measurements, the FloTrac system was influenced to a higher degree by arterial blood pressure, resulting in consistent overestimation of cardiac output. CLINICAL RELEVANCE: The FloTrac monitor, whose algorithms were developed based on human data, cannot be used as an alternative for thermodilution in dogs.

Continuous versus intermittent thermodilution for cardiac output measurement during alveolar recruitment manoeuvres in sheep.

OBJECTIVE: To evaluate interchangeability of a thermodilution based STAT mode continuous cardiac output (CCO) measurement method with bolus thermodilution (BTD). STUDY DESIGN: Randomized crossover study. ANIMALS: Ten 9 month old healthy male sheep. METHODS: Each sheep was anaesthetized twice for laparoscopy. On one occasion mechanical ventilation was used immediately after anaesthetic induction (IPPV treatment) and on the other occasion the start of IPPV was delayed and two periods of alveolar recruitment manoeuvres were also performed (RM treatment). Cardiac output (CO) was measured simultaneously with both CCO and BTD at 6 time points. Data were analysed using difference versus mean plots. A priori limits of acceptance were set at ±30% of the mean of every paired measurement. If <5% of the data fell outside of these limits (Chi-square test, p<0.05) the interchangeability of methods was accepted. Proportions of data outside of these limits were also compared between treatments (Fisher's test, p <0.05). Cardiac output data from each treatment and measurement method were also analyzed separately with one-factorial anova and Bonferroni test (p<0.05). RESULTS: A total of 119 measurements were obtained. Cardiac output ranged from 1.9 to 10.4 L minute(-1) (CCO) and from 1.1 to 9.8 L minute(-1) (BTD). The bias and limits of agreement were 0.5±1.9 L minute(-1) . More than 5% of all data fell outside of the limits of acceptance (24/119), and a larger proportion fell outside of these limits in the RM (20/59) compared to the IPPV treatment (4/60). The Bonferroni test detected significant decreases of CO over time in both treatments when measured with BTD but not with CCO. CONCLUSIONS AND CLINICAL RELEVANCE: The STAT mode CCO method is not interchangeable with BTD during acute haemodynamic changes caused by recruitment manoeuvres, thus the results of STAT mode CCO should be interpreted with caution because decreases in CO may not be detected.

Bispectral index and the clinically evaluated anaesthetic depth in dogs.

OBJECTIVE: This study investigated whether the bispectral index (BIS monitor) corresponded with the clinical assessment of anaesthetic depth in dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: Sixty-five dogs undergoing anaesthesia for surgery. METHODS: Dogs were assigned to one of three different anaesthetic techniques. A three point scale was devised to determine the clinical depth of anaesthesia (CDA); CDA 1 represented light, CDA 2 surgical and CDA 3 excessive depth of anaesthesia. BIS values were recorded and CDA assessed at specific times and points throughout surgery. Data were statistically analysed using mixed model regression. RESULTS: Clinical depth of anaesthesia was assessed as CDA 1 on 68, 2 on 748 and 3 on four occasions. The BIS recorded for CDA 1 differed significantly from that for CDA 2 (p<0.001). However, individual BIS values measured at light and surgical levels of anaesthesia overlapped considerably. The sensitivities and specificities calculated for BIS to diagnose CDA 1 compared to CDA 2 in the three anaesthetic protocols were 28-86% and 55-85%. The accompanying positive predictive value was 0.08-0.29 and the negative predictive value was 0.95-0.97. End-tidal isoflurane concentrations (anaesthetic techniques 1 and 3) and propofol infusion (technique 2) at CDA 1 was significantly lower than those at CDA 2 (p=0.001). CONCLUSIONS: Although BIS values overall distinguished between CDA scores, the calculated specificities, sensitivities and predictive values were low, and there were anomalous results in individual cases. CLINICAL RELEVANCE: The use of the BIS as the sole method to determine anaesthetic depth in dogs is imprudent.

Bispectral monitoring in dogs subjected to ovariohysterectomy and anesthetized with halothane, isoflurane or sevoflurane.

OBJECTIVE: To assess the effect of halothane (H), isoflurane (I) or sevoflurane (S) on the bispectral index (BIS), and the effect of the addition of meperidine in dogs subjected to ovariohysterectomy. STUDY DESIGN: Prospective, randomized, blinded, clinical trial. ANIMALS: Forty-eight female mixed-breed dogs, with weights varying from 10 to 25 kg. METHODS: All dogs were premedicated with acepromazine (A) (0.1 mg kg(-1) IM) or A and meperidine (M) (3 mg kg(-1) IM) and they were divided into six groups of eight animals (AH, AMH, AI, AMI, AS, and AMS). Fifteen minutes after premedication they were anesthetized with propofol (5 mg kg(-1) IV) and then orotracheally intubated. Anesthesia was maintained with halothane, isoflurane or sevoflurane, respectively. The BIS, variables were recorded at 15 minutes after administering pre-anesthetic medication (T0); 10 minutes of anesthesia maintenance (T1); right ovarian pedicle ligation (T2); muscle suturing (T3); skin suture (T4) and 10 minutes after terminating the inhalant anesthetic (T5), respectively. RESULTS: BIS values were decreased at all times when compared to the baseline values in all groups (p<0.05). In the comparative assessment between groups, the values obtained at T0 and T1 were similar for all groups. At T2, the values in AMH were lower than those obtained in AI, AMI and AS (p<0.05). At the same time significantly higher values were found for AI when compared to AMS (p<0.01). There was a correlation between the bispectral index and the expired anesthetic fraction in all groups. CONCLUSIONS AND CLINICAL RELEVANCE: Within groups given the same inhalant anesthetic the bispectral index was a good indicator for the degree of hypnosis in dogs, indicating a good correlation with the amount of anesthetic and the nociceptive stimulation. BIS was a less reliable indicator of relative anesthetic depth when comparing equipotent end-tidal concentrations between the three inhalants.

Simultaneous percutaneous implantation of a microdialysis probe for monitoring perineural concentrations of local anaesthetics during peripheral nerve block in rabbits.

OBJECTIVE: To develop a technique that allows simultaneous percutaneous implantation of both a microdialysis probe and injection catheter in order to monitor the perineural pharmacokinetics of local anaesthetics (LA) after a femoral block. STUDY DESIGN: Prospective experimental study. ANIMALS: Five anaesthetized male New Zealand rabbits with a mean ± SD weight of 3.2 ± 0.2 kg. METHODS: After femoral nerve localization by electrostimulation, an injection catheter and a microdialysis probe were slowly and simultaneously inserted into a cannula left into place in the perineural region. Both were then secured into place, after removal of the cannula. At the end of the experiment, methylene blue was injected to confirm the distance from the femoral nerve during subsequent postmortem anatomical dissection of the injection site. RESULTS: Staining was adequate and the catheter found to be located within 4 mm of the femoral nerve in three out of five rabbits. CONCLUSIONS AND CLINICAL RELEVANCE: This procedure allows direct implantation of a microdialysis probe near the injection site of LA during a femoral nerve block without loosing nerve localization accuracy. This procedure has been used successfully to monitor the regional pharmacokinetics of LA after a peripheral nerve block.

Metabolic acidosis in healthy mules under general anaesthesia with halothane.

OBJECTIVE: To report the severe metabolic acidosis identified in a group of 11 healthy mules anaesthetized with halothane for castration. STUDY DESIGN: Data generated from a prospective study. ANIMALS: Eleven mules aged 2.5-8 years, weighing 230-315 kg and 11 horses aged 1.5-3.5 years, weighing 315-480 kg. METHODS: Animals were anaesthetized for castration as part of an electroencephalographic study. Preanaesthetic medication was acepromazine (0.03 mg kg(-1) ) administered through a preplaced jugular venous catheter. Anaesthesia was induced 30-90 minutes later with intravenous thiopental (10 mg kg(-1) ). After orotracheal intubation, anaesthesia was maintained with halothane vaporised in oxygen. The animals' lungs were ventilated to maintain the end-tidal CO(2) concentration between 3.9 and 4.5 kPa (29-34 mmHg). Anaesthetic monitoring included invasive blood pressure measurement via the auricular artery (mules) and submandibular branch of the facial artery (horses). Arterial blood gas samples were drawn from these catheters at three time points during surgery and pH, PaCO(2) , base excess (ecf) and were measured. Values were compared between groups using a Mann-Whitney test. p was taken as <0.05. Results are reported as median (range). RESULTS: PaCO(2) did not differ between groups but pH was significantly lower in mules [7.178 (7.00-7.29)] compared to horses [7.367 (7.24-7.43)] (p=0.0002). values were significantly lower in the mules [16.6 (13.0-22.3) mM] compared to horses [23.7 (20.9-23.7) mM] (p=0.0001), whilst base excess (ecf) was significantly more negative in the mules [-11.4 (-1.27 to -16) mM] compared to horses [-1.3 (-5.8 to +2.4) mM] (p=0.0004). CONCLUSION AND CLINICAL RELEVANCE: This study demonstrated severe metabolic acidosis in healthy mules, which may have prompted intervention with drug therapies in a clinical arena. It is probable that the acidosis existed prior to anaesthesia and caused by diet, but other possible causes are considered.

Influence of a preload of hydroxyethylstarch 6% on the cardiovascular effects of epidural administration of ropivacaine 0.75% in anaesthetized dogs.

OBJECTIVE: To evaluate the cardiovascular effects of a preload of hydroxyethylstarch 6% (HES), preceding an epidural administration of ropivacaine 0.75% in isoflurane anaesthetized dogs. ANIMALS: Six female, neutered Beagle dogs (mean 13.3 ± SD 1.0 kg; 3.6 ± 0.1 years). STUDY DESIGN: Randomized experimental cross-over study (washout of 1 month). METHODS: Anaesthesia was induced with propofol and maintained with isoflurane in oxygen/air. All dogs were anaesthetized twice to receive either treatment HESR (continuous rate infusion [CRI] of 7 mL kg(-1) HES started 30 minutes [T-30] prior to epidural administration of ropivacaine 0.75% 1.65 mg kg(-1) at T0) or treatment R (no HES preload and similar dose and timing of epidural ropivacaine administration). Baseline measurements were obtained at T-5. Heart rate (HR), mean (MAP), diastolic (DAP) and systolic (SAP) invasive arterial pressures, cardiac output (Lithium dilution and pulse contour analysis) and derived parameters were recorded every 5 minutes for 60 minutes. Statistical analysis was performed on five dogs, due to the death of one dog. RESULTS: Clinically relevant decreases in MAP (<60 mmHg) were observed for 20 and 40 minutes following epidural administration in treatments HESR and R respectively. Significant decreases in MAP and DAP were present after treatment HESR for up to 20 minutes following epidural administration. No significant within-treatment and overall differences were observed for other cardiovascular parameters. A transient unilateral Horner's syndrome occurred in two dogs (one in each treatment). One dog died after severe hypotension, associated with epidural anaesthesia. CONCLUSIONS AND CLINICAL RELEVANCE: A CRI of 7 mL kg(-1) HES administered over 30 minutes before epidural treatment did not prevent hypotension induced by epidural ropivacaine 0.75%. Epidural administration of ropivacaine 0.75% in isoflurane anaesthetized dogs was associated with a high incidence of adverse effects in this study.

Transoperative glycemia in pets: validating old ones, and presenting lip mucosa as new sampling site.

The aim of our study was to investigate the viability and validity of blood sampling from the upper lip mucosa in healthy dogs and cats for monitoring transoperative glycemia and compare the results with those obtained from samples taken from previously described blood sampling sites for determination of glycemia using a glucose meter. Blood glucose (BG) levels were determined in samples taken from the upper lip mucosa of 24 dogs and 31 cats undergoing neutering or spaying surgeries. These values were compared to those of samples obtained from other sites previously described for capillary blood glucose monitoring (marginal ear vein, carpal pad in dogs, metacarpal pad in cats) using a glucose meter. Additionally, BG from peripheral venous blood was determined using a glucose meter, and the gold standard enzymatic colorimetric assay. The clinical reliability of BG values taken from lip mucosa and from all the other BG values measured by the glucose meter was evaluated using the error grid analysis modified by Parkes et al (2000). The upper lip mucosa was an easily accessible site for the obtainment of appropriate blood samples, and glucose levels read in these samples correlated positively with glycemic values read in blood samples from all other sites in dogs and cats. All BG made using glucose meters taken from all sites were within the clinically acceptable range when compared with enzymatic colorimetric assay (gold standard), and were analytically accurate according to the error grid (zones A and B). All blood sampling sites described in this work can be used to assess transoperative glycemia. The upper lip mucosa is a viable blood sampling site for precise monitoring of transoperative glycemia in healthy dogs and cats and shows promise for alternative blood glucose monitoring.

Reversal of profound rocuronium block monitored in three muscle groups with sugammadex in ponies.

BACKGROUND: This clinical study evaluated the speed of reversal of profound rocuronium block in ponies using sugammadex and investigated the differences in onset and recovery from block in three different muscle groups. METHODS: Anaesthesia was induced and maintained with isoflurane in oxygen 100% in eight ponies. Neuromuscular monitoring was performed at each site using acceleromyography: in the extensor muscles of the pelvic limb (peroneal nerve) and thoracic limb (radial nerve), and in the orbicularis oris muscle (OOM; facial nerve). Rocuronium 0.6 mg kg(-1) i.v. was administered, followed 5 min later by sugammadex 4 mg kg(-1) i.v. Onset time (onsetROC), maximum block, and time to recovery of the train-of-four ratio to 0.9 (TOFR=0.9) were recorded. The differences between monitored sites were compared using one-way anova followed by a post hoc Dunn's test. RESULTS: Onset of ROC was significantly delayed in OOM compared with both limbs [pelvic limb, thoracic limb, and OOM: 43.1 (sd 16.9), 50.6 (15.9), and 204.4 (35.8) s, respectively; P<0.001]. Complete block was achieved in the pelvic and thoracic limbs, but in none of the eight ponies in the OOM [mean T1=15.3 (9.4)%; range: 7-36%]. No differences were observed between muscle sites in recovery to TOFR=0.9 [pelvic limb, thoracic limb, and OOM: 2.3 (0.9), 3.4 (1.7), and 2.8 (2.1) min, respectively]. No adverse effects of sugammadex were detected throughout the study period. CONCLUSIONS: Sugammadex can be used to reverse profound rocuronium-induced block in ponies during isoflurane anaesthesia. Thoracic limb muscles represent a suitable alternative for monitoring neuromuscular block compared with pelvic limb muscles.

Fluid balance, glomerular filtration rate, and urine output in dogs anesthetized for an orthopedic surgical procedure.

OBJECTIVE: To determine fluid retention, glomerular filtration rate, and urine output in dogs anesthetized for a surgical orthopedic procedure. ANIMALS: 23 dogs treated with a tibial plateau leveling osteotomy. PROCEDURES: 12 dogs were used as a control group. Cardiac output was measured in 5 dogs, and 6 dogs received carprofen for at least 14 days. Dogs received oxymorphone, atropine, propofol, and isoflurane for anesthesia (duration, 4 hours). Urine and blood samples were obtained for analysis every 30 minutes. Lactated Ringer's solution was administered at 10 mL/kg/h. Urine output was measured and glomerular filtration rate was estimated. Fluid retention was measured by use of body weight, fluid balance, and bioimpedance spectroscopy. RESULTS: No difference was found among control, cardiac output, or carprofen groups, so data were combined. Median urine output and glomerular filtration rate were 0.46 mL/kg/h and 1.84 mL/kg/min. Dogs retained a large amount of fluids during anesthesia, as indicated by increased body weight, positive fluid balance, increased total body water volume, and increased extracellular fluid volume. The PCV, total protein concentration, and esophageal temperature decreased in a linear manner. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs anesthetized for a tibial plateau leveling osteotomy retained a large amount of fluids, had low urinary output, and had decreased PCV, total protein concentration, and esophageal temperature. Evaluation of urine output alone in anesthetized dogs may not be an adequate indicator of fluid balance.

Development of perioperative care for pigs undergoing laryngeal transplantation: a case series.

Pigs are ideal animal models for airway surgical research, facilitating the successful translation of science into clinical practice. Despite their ubiquitous use, there is a paucity of information on the perioperative care of pigs, especially for major procedures. In a series of experiments to investigate laryngeal transplantation, we combined veterinary and medical experience to develop protocols for perioperative management of pigs, including high dependency care. Novel airway management methods were developed. A pain scoring system was used to direct analgesia use. Fluid balance and electrolytes were monitored closely. Recent animals received a central venous line via the femoral vein two days prior to transplantation to facilitate blood sampling and drug delivery. Intensive monitoring and airway management were required to ensure a successful outcome. Methods for optimal perioperative care are proposed. These results will help future groups wishing to use pigs in airway research, will reduce numbers of animals used and improve animal welfare.

Design and evaluation of a low-cost respiratory monitoring device for use with anaesthetized animals.

This report describes a simple, non-invasive electronic device that employs a compact accelerometer integrated circuit to transduce movements in the chest wall of an anaesthetized animal into an analogue signal that can be used to calculate the rate and relative depth of respiration. The device requires amplification by signal processing hardware/software which are common to most experimental laboratories. We assessed the sensitivity of the device by its ability to detect changes in respiratory patterns produced by modulating the depth of anaesthesia in isoflurane-anaesthetized Wistar rats. It is widely accepted that many anaesthetic agents affect respiratory patterns, especially respiratory rate (RR), which is often used as an important index of anaesthetic depth. Respiratory parameters obtained with the device were compared with concurrently recorded electroencephalographic and cardiac measures. Different concentrations of anaesthetic agent produced four depths of anaesthesia, identified using established electroencephalographic criteria. The accelerometer was attached easily and securely to the location of maximal chest wall movement and produced a strong respiratory signal that was detectable in all four anaesthetic stages. Deepening the anaesthesia produced a gradual decrease in RR, a decrease in dominant spectral frequency of the electroencephalogram (EEG) but no change in the heart rate. There was a significant correlation between RR and the dominant spectral frequency of the EEG, indicating that one useful application of the monitor could be to identify anaesthetic stages. The results demonstrate that respiratory parameters can be recorded using a simply constructed, low-cost device and suggest an application in the monitoring of anaesthetic depth.