Thoracic epidural anaesthesia vs intrathecal morphine in dogs undergoing major thoracic and abdominal surgery: clinical study.

BACKGROUND: There is scant clinical research on neuraxial analgesia in dogs undergoing major surgery. With this study we compared the perioperative analgesic effects of thoracic epidural anaesthesia (TEA) and intrathecal morphine (ITM) in dogs scheduled for thoracic or cranial abdominal surgery. The dogs received methadone and dexmedetomidine, were anaesthetized with propofol maintained with sevoflurane, and randomly assigned to receive either TEA (ropivacaine 0.5% at 0.2 mg/kg and morphine 0.1 mg/kg administered at T12-T13) or ITM (morphine 30 µg/kg administered at L6-L7). Intraoperative rescue analgesia (iRA) was fentanyl 1 µg/kg administered if heart rate or mean arterial pressure increased by 30% above the pre-stimulation level. Glasgow Pain Composite Scale score (GPCS) dictated the use of postoperative rescue analgesia (pRA) with methadone 0.2 mg/kg. RESULTS: There was a statistically significant difference in iRA, median time to first fentanyl bolus, median fentanyl dose after surgical opening, and median GPCS score at 30 minutes (min), 1 ,2, 4, 6, and 8 hours (h) between the two groups (p<0.001; p<0.001; p<0.001; p<0.01; p<0.01; p<0.001; p<0.01; p=0.01; p=0.01, respectively). Fewer TEA than ITM group dogs required iRA during surgical opening and pRA: 5% (1/18) and 2/18 (11%), respectively, in the TEA and 83% (16/18) and 10/18 (55%), respectively, in the ITM group. Side effects were urinary retention in 3/18 (16%) TEA group dogs and 2/18 (11%) ITM group dogs and prolonged sedation in 2/18 (11%) in ITM group dogs. TEA and ITM were effective in managing perioperative pain in dogs undergoing thoracic or cranial abdominal surgery.

Effects of intravenous dexmedetomidine infusion on local anaesthetic block: A spinal anaesthesia clinical model in dogs undergoing hind limb surgery.

The aim of this randomised, prospective clinical trial was to determine how the administration of a low dose of dexmedetomidine (DEX) by IV constant rate infusion, modified the duration of the nerve block in dogs undergoing spinal anaesthesia (SA) in a clinical setting. Forty-four dogs undergoing hind limb orthopaedic surgery in a day-surgery regime, maintained under anaesthesia with isoflurane plus SA, were randomly assigned to receive 1 µg/kg/h (IV) of DEX (group D) or not (group C). Spinal anaesthesia was performed with a hyperbaric solution of bupivacaine and morphine at the L5-6 interspace. Every mean arterial pressure (MAP) increase by 30% above the pre-skin incision value was considered an intraoperative analgesic failure and treated with a bolus of fentanyl as intraoperative rescue analgesia (iRA). Time free from iRA was analysed with a Kaplan-Maier survival curve. The ability to walk at 5 h from SA and the event of bradycardia (HR lower 60 beat per min) and hypotension (MAP value lower 60 mmHg) were recorded. The mean times at which iRA was required were 77.4 (3.2) in group C and 112.2 (8.6) in group D (Logrank test P = 0.038). In groups C and D hypotension incidence was 11/17 (65%) and 2/22 (9%), (P = 0.0004) and bradycardia 3/17 (18%) and 6/22 (27%) (P = 0.704), respectively. The ability to walk 5 h after SA was 14/14 (100%) and 13/14 (93%) in groups C and D, respectively. DEX infusion significantly prolonged the duration of the nociceptive nervous block without prolonging the motor block or increasing the bradycardia events.

Respiratory variation in aortic blood peak velocity and caudal vena cava diameter can predict fluid responsiveness in anaesthetised and mechanically ventilated dogs.

BACKGROUND AND M&MS: Dynamic preload indices, such as systolic pressure variation (SPV), aortic flow peak velocity variation (ΔVpeak) and distensibility index of the caudal vena cava (CVCDI), are reliable indices for predicting fluid responsiveness in humans. This study aimed to investigate the ability of these indices to predict fluid response in 24 healthy dogs undergoing general anaesthesia and mechanical ventilation. Aortic flow peak velocity variation (∆Vpeak), CVCDI, and SPV were calculated before volume expansion (5mL/kg bolus of lactated Ringer's solution). The aortic velocity time integral (VTI) was measured before and after volume expansion as a surrogate of stroke volume. Dogs were considered responders (n=9) when the VTI increase was ≥15% and non-responders (n=15) when the increase was <15%. RESULTS AND CONCLUSIONS: Before volume expansion, ΔVpeak, CVCDI and SPV were higher in responders than in non-responders (P=0.0009, P=0.0003, and P=0.0271, respectively). Receiver operating characteristic (ROC) curves were plotted for the three indices. The areas under the ROC curves for SPV, ΔVpeak, and CVCDI were 0.91 (CI 0.73-0.99; P=0.0001), 0.95 (CI 0.77-1; P=0.0001), and 0.78 (CI 0.56-0.92; P=0.015), respectively. The best cut-offs were 6.7% for SPV (sensitivity, 77.78%; specificity, 93.33%), 9.4% for ΔVpeak (sensitivity, 88.89%; specificity, 100%), and 24% for CVCDI (sensitivity, 77.78%; specificity, 73.33). In conclusion, ΔVpeak, CVCDI, and SPV are reliable predictors of fluid responsiveness in healthy dogs undergoing general anaesthesia and mechanical ventilation.

Evaluation and optimisation of propofol pharmacokinetic parameters in cats for target-controlled infusion.

The aim of this study was to develop and evaluate a pharmacokinetic model-driven infusion of propofol in premedicated cats. In a first step, propofol (10 mg/kg) was administered intravenously over 60 seconds to induce anaesthesia for the elective neutering of seven healthy cats, premedicated intramuscularly with 0.3 mg/kg methadone, 0.01 mg/kg medetomidine and 2 mg/kg ketamine. Venous blood samples were collected over 240 minutes, and propofol concentrations were measured via a validated high-performance liquid chromatography assay. Selected pharmacokinetic parameters, determined by a three-compartment open linear model, were entered into a computer-controlled infusion pump (target-controlled infusion-1 (TCI-1)). In a second step, TCI-1 was used to induce and maintain general anaesthesia in nine cats undergoing neutering. Predicted and measured plasma concentrations of propofol were compared at specific time points. In a third step, the pharmacokinetic parameters were modified according to the results from the use of TCI-1 and were evaluated again in six cats. For this TCI-2 group, the median values of median performance error and median absolute performance error were -1.85 per cent and 29.67 per cent, respectively, indicating that it performed adequately. Neither hypotension nor respiratory depression was observed during TCI-1 and TCI-2. Mean anaesthesia time and time to extubation in the TCI-2 group were 73.90 (±20.29) and 8.04 (±5.46) minutes, respectively.

Lethal septic shock after dental scaling in a healthy dog due to Ochrobactrum anthropi-contaminated propofol.

A 10-year-old, 6-kg male Yorkshire terrier dog was scheduled for routine dental cleaning. No significant problem was observed either during anaesthesia, which was induced with propofol, or during recovery. However, 2 hours after discharge, the dog's owner returned to the clinic, complaining that the animal was lethargic and had had bloody diarrhoea. On physical examination the dog was depressed, dyspnoeic, tachycardic and hypoglycaemic. Despite supportive treatment, the dog deteriorated and died within a few hours.A presumed diagnosis of sepsis was confirmed by laboratory testing. Bacteriological and molecular examinations of both premortem blood samples and the anaesthetic, highlighted the presence of Ochrobactrum anthropi, an opportunistic pathogen usually associated with immunocompromised hosts with indwelling medical devices. To the authors' knowledge, this is the first case of sepsis in a healthy dog due to contamination of an anaesthetic solution by O. anthropi, suggesting a potential role of this microorganism as an emerging pathogen.

Use of systolic pressure variation to predict the cardiovascular response to mini-fluid challenge in anaesthetised dogs.

Systolic pressure variation (SPV), the maximum variation in systolic pressure values following a single positive pressure breath delivered by controlled mechanical ventilation (CMV), is highly correlated with volaemia in dogs. The aim of this study was to determine an SPV value that would indicate when fluid administration would be beneficial in clinical practice. Twenty-six client-owned dogs were anaesthetised, following which CMV with a peak inspiratory pressure (PIP) of 8 cmH2O was applied. After SPV measurement and recording of heart rate (HR) and blood pressure (BP), 3 mL/kg fluid were administered, then HR and BP were recorded again. Dogs exhibiting a 10% decrease in HR and/or an increase in BP were defined as responders, and their SPV pre-bolus was analysed retrospectively. SPV values > 4 mmHg or >4.5% predicted haemodynamic improvement in dogs with normal cardiovascular function, with a sensitivity of 90% and a specificity of 87%. The area under the curve receiver operating characteristic value for SPV was 0.931 mmHg (95% confidence interval, CI, 0.76-0.99 mmHg) and 0.944% (95% CI 0.78-0.99%). It is proposed that SPV values > 4.5% in dogs with a normal cardiovascular function, anaesthetised with isoflurane in oxygen and air, and on CMV (PIP 8 cmH2O), can be used to predict a cardiovascular response (>10% increase in mean arterial BP and/or >10% decrease in heart rate).

Post anaesthetic myopathy/neuropathy in horses undergoing magnetic resonance imaging compared to horses undergoing surgery.

REASONS FOR PERFORMING STUDY: Patient positioning and long anaesthetic duration required for magnetic resonance imaging (MRI) may result in a higher frequency of post anaesthetic myopathy/neuropathy syndrome (PAMNS) as compared to horses undergoing anaesthesia for surgery. HYPOTHESIS: Equine anaesthesia for MRI is associated with a higher frequency of PAMNS than anaesthesia for nonemergency, nonabdominal surgery. METHODS: Anaesthetic and medical records of horses (n = 633) undergoing MRI or surgery between January 2001 and January 2005 (inclusive), were reviewed. Information obtained included patient details (breed, sex, age, bodyweight), area of body scanned or involved in surgery, body position, anaesthetic and inotropic agents administered, anaesthetic duration, adverse events during anaesthesia and outcome at 7 days. Data were examined by cross tabulation and Chi-square or Fisher's exact test of association. The influence of individual variables was examined by univariant and multivariant analysis models. RESULTS: There were no statistically significant differences between the 2 groups in parameters examined, except that horses in the MRI group were heavier (P<0.0001) and anaesthetic duration longer in the surgery group (P<0.004). Eight horses (2.3%, 95% Confidence interval [CI]: 1.1-4.2) in the MRI group had clinical signs of PAMNS in the post anaesthetic period, whereas only 2 horses (0.98%, 95% CI: 0.2-2.8) in the surgery group were affected. This was not statistically significantly different (odds ratio = 2.7, 95% CI: 0.8-13, P = 0.3). Two horses undergoing MRI were subjected to euthanasia due to the severity of PAMNS. CONCLUSIONS: There was no difference in the occurrence of PAMNS between the 2 groups. POTENTIAL RELEVANCE: The risk of performing general anaesthesia for diagnostic procedures such as MRI may not be greater than that for a surgical procedure. However, the benefits should be carefully weighed against the risks involved.

[Genetic counseling in cancerology]. / Le counseil génétique en cancérologie.

The authors have studied the different situations that prompt a request for genetic counseling if different members of the same family suffer from cancer. Six possibilities are considered: the cancer concerned is a genetic disease per se (e.g. retinoblastoma, thyroid cancer with amyloid stroma); the genetic disease is often complicated with cancer (e.g. intestinal polyposis); the genetic disease is occasionally complicated with cancer (e.g. neurofibromatosis); cancer is part and parcel of the genetic disease (e.g. chromosomal abnormalities); in addition, there are two special situations: "cancer-prone families" and families who request genetic counseling after one single case (e.g. cancer of leukaemia in a child).