The coasting time affects the quality of cumulus-oocyte complexes in superstimulated ewes.

We hypothesized that the coasting time may be beneficial to the quality of cumulus-oocyte complexes recovered from live ewes, as reported in cattle. The present study assessed the effect of coasting times on the quantity and quality of cumulus-oocyte complexes (COCs) in sheep. All ewes were subjected to the "Day 0 protocol", followed by an ovarian stimulation (80 mg of pFSH in three decreasing doses), varying only the coasting time [12 (G12), 36 (G36), or 60 h (G60]. In Experiment 1, data regarding follicular population was assessed. In Experiment 2, the COC quality was checked by their morphology, brilliant cresyl blue (BCB) test, evaluation of chromatin condensation pattern, and oocyte diameter. In Experiment 3, genes related to oocyte developmental competence were evaluated in BCB + COCs. The oocytes in the G60 group had more (P < 0.05) large follicles than the other groups and oocytes with a greater diameter than the G12. Oocyte morphology was similar (P > 0.05) among groups, as well as the BCB + COCs quantity. The G60-oocytes presented a better (P < 0.05) configuration of chromatin condensation compared with the other groups and a greater (P < 0.05) gene expression of BMP15, MATER, ZAR1, and PTGS2 compared with G12, and PTGS2 and HAS2 compared with G36 group. In conclusion, 60 h of coasting time positively affects the quality of COCs recovered after subjecting ewes to the "Day 0 protocol" and ovarian superstimulation. Implementing the appropriate coasting time to a given protocol can positively impact the in vitro embryo production outcomes in sheep.

Isoflurane MAC determination in dogs using three intensities of constant-current electrical stimulation.

OBJECTIVES: To compare isoflurane minimum alveolar concentrations (MACs) in dogs determined using three intensities of constant-current electrical stimulation applied at the tail, and thoracic and pelvic limbs, and to compare isoflurane MACs obtained with all combinations of electrical stimulation and anatomic site with those obtained using the tail clamp as the noxious stimulus. STUDY DESIGN: Randomized trial. ANIMALS: Six mixed-breed, adult female dogs aged 1-2 years and weighing 11.1 ± 4.4 kg. METHODS: In each dog, MAC was determined by the bracketing method with the tail clamp (MACTAILCLAMP ), and three electrical currents (10 mA, 30 mA, 50 mA) at three anatomic sites (thoracic limb, pelvic limb, tail). Each MAC achieved with electrical stimulation was compared with MACTAILCLAMP using a mixed-model anova and Dunnett's procedure for multiple comparisons. The effects of current intensity and anatomic site on isoflurane MAC were tested using a mixed-model anova followed by Tukey's test for multiple comparisons (p < 0.05). RESULTS: Mean MACTAILCLAMP was 1.69%. MACs achieved with currents of 30 mA and 50 mA did not differ independently of anatomic site. When currents of 10 mA were applied to the tail and thoracic limb, resulting MACs were lower than those obtained using currents of 30 mA and 50 mA. Currents of 30 mA and 50 mA provided MACs that did not differ from those of MACTAILCLAMP , whereas a current of 10 mA achieved the same result only for the pelvic limb. CONCLUSIONS AND CLINICAL RELEVANCE: Isoflurane MAC is affected by current intensity and anatomic site. Current intensities of 30 mA and 50 mA provided consistent results when applied to the tail, and thoracic and pelvic limbs that did not differ from those obtained using the tail clamp. Consequently, they can be used in place of the tail clamp in MAC studies in dogs.

The sheep as a model for healing studies after partial nephrectomy.

BACKGROUND: The pig has been considered the best model for renal surgery. However, recent research has demonstrated that the kidney of pigs heals differently from that of humans. The objective of this study was to evaluate sheep as an alternative animal model for studying collecting system healing after laparoscopic partial nephrectomy. MATERIALS AND METHODS: The caudal pole of the left kidney was removed from eight female adult domestic sheep using laparoscopic partial nephrectomy. Monopolar energy was used for hemostasis only in the parenchyma, avoiding coagulation near the collecting system, which was left opened. After 14 d, all animals were euthanized, and their left kidney was removed. Serum levels of urea and creatinine were assessed preoperatively and postoperatively (on days 2, 6, 10, and 14), and peritoneal fluid samples were collected during necropsy for urea and creatinine evaluation. An ex vivo retrograde pyelogram was performed, and a retrograde injection of methylene blue ink was administered to evaluate urinary leakage. Samples from the operated pole were analyzed using histologic methods. RESULTS: During necropsy, an urinoma surrounding the operated kidney was observed in one animal. Peritoneal fluid levels of urea and creatinine were elevated. Retrograde pyelograms exhibited contrast-medium extravasation through the operated pole in all kidneys. The opened collecting system was also confirmed by methylene blue ink injection. The operated pole was covered by collagenous tissue and adhered to adjacent organs. CONCLUSIONS: Sheep should be considered as an adequate experimental model for research on collecting system healing after partial nephrectomy.

Positive end-expiratory pressure at minimal respiratory elastance represents the best compromise between mechanical stress and lung aeration in oleic acid induced lung injury.

INTRODUCTION: Protective ventilatory strategies have been applied to prevent ventilator-induced lung injury in patients with acute lung injury (ALI). However, adjustment of positive end-expiratory pressure (PEEP) to avoid alveolar de-recruitment and hyperinflation remains difficult. An alternative is to set the PEEP based on minimizing respiratory system elastance (Ers) by titrating PEEP. In the present study we evaluate the distribution of lung aeration (assessed using computed tomography scanning) and the behaviour of Ers in a porcine model of ALI, during a descending PEEP titration manoeuvre with a protective low tidal volume. METHODS: PEEP titration (from 26 to 0 cmH2O, with a tidal volume of 6 to 7 ml/kg) was performed, following a recruitment manoeuvre. At each PEEP, helical computed tomography scans of juxta-diaphragmatic parts of the lower lobes were obtained during end-expiratory and end-inspiratory pauses in six piglets with ALI induced by oleic acid. The distribution of the lung compartments (hyperinflated, normally aerated, poorly aerated and non-aerated areas) was determined and the Ers was estimated on a breath-by-breath basis from the equation of motion of the respiratory system using the least-squares method. RESULTS: Progressive reduction in PEEP from 26 cmH2O to the PEEP at which the minimum Ers was observed improved poorly aerated areas, with a proportional reduction in hyperinflated areas. Also, the distribution of normally aerated areas remained steady over this interval, with no changes in non-aerated areas. The PEEP at which minimal Ers occurred corresponded to the greatest amount of normally aerated areas, with lesser hyperinflated, and poorly and non-aerated areas. Levels of PEEP below that at which minimal Ers was observed increased poorly and non-aerated areas, with concomitant reductions in normally inflated and hyperinflated areas. CONCLUSION: The PEEP at which minimal Ers occurred, obtained by descending PEEP titration with a protective low tidal volume, corresponded to the greatest amount of normally aerated areas, with lesser collapsed and hyperinflated areas. The institution of high levels of PEEP reduced poorly aerated areas but enlarged hyperinflated ones. Reduction in PEEP consistently enhanced poorly or non-aerated areas as well as tidal re-aeration. Hence, monitoring respiratory mechanics during a PEEP titration procedure may be a useful adjunct to optimize lung aeration.

Neuromuscular blocking properties of atracurium during sevoflurane or propofol anaesthesia in dogs.

OBJECTIVE: To quantify the neuromuscular blockade (NMB) produced by atracurium in either sevoflurane or propofol-anaesthetized dogs. ANIMALS: Twelve healthy, female adult mixed-breed dogs weighing 13 +/- 3 kg (range 10-22 kg). MATERIALS AND METHODS: Three doses of atracurium (0.1, 0.2 and 0.3 mg kg(-1)) were tested at 1-week intervals. Anaesthesia was induced with inhaled sevoflurane or intravenous propofol and maintained with end-tidal sevoflurane concentrations of 1.95% (1.25 x MAC) or propofol 0.6 mg kg(-1) minute(-1) respectively. Acceleromyography and train-of-four stimulation of the fibular nerve were used for the assessment of NMB. The percentage depression of the first twitch (T1) and the fourth to the first twitch ratio (T4/T1), the maximum degree of neuromuscular block achieved and surgical muscle relaxation were recorded. Before and during neuro muscular blockade (at 10 minute intervals) body temperature, ECG, arterial blood pressure, inspired and expired CO2 concentrations and SpO2 were recorded. RESULTS: Atracurium produced a dose-dependent duration of NMB in both propofol and sevoflurane-anaesthetized dogs. Duration of block was longer in dogs anaesthetized with sevoflurane. All studied doses of atracurium caused twitch depression > or =95% with little or no cardiovascular changes. CONCLUSIONS: Sevoflurane produces a clinically relevant potentiation of atracurium-induced NMB in dogs compared with propofol. CLINICAL RELEVANCE: Significant differences in the potentiation of NMB drugs are encountered with commonly used anaesthetics in the dog.

Isoflurane sparing action of epidurally administered xylazine hydrochloride in anesthetized dogs.

OBJECTIVE: To evaluate the influence of epidural administration of xylazine hydrochloride on the minimum alveolar concentration of isoflurane (MAC(ISAO)) and cardiopulmonary system in anesthetized dogs. ANIMALS: 6 clinically normal dogs. PROCEDURE: Dogs were anesthetized with isoflurane in oxygen after randomly being assigned to receive 1 of the following 4 treatments: epidural administration of saline (0.9% NaCl) solution or xylazine at a dose of 0.1, 0.2, or 0.4 mg x kg(-1). Experiments were performed on 5 occasions with at least a 1-week interval between experiments; each dog received all 4 treatments. Following instrumentation, the concentration of isoflurane was maintained constant for 15 minutes at the MAC(ISO) that had been determined for each dog, and data on heart rate, arterial blood pressure, respiratory rate, tidal volume, minute volume, arterial partial pressure of oxygen, arterial partial pressure of carbon dioxide, and arterial pH were collected. The epidural treatment was administered, and 30 minutes later, data were again collected. From this point on, determination of the MAC(ISO) following epidural treatment (ie, MAC(ISO+EPI)) was initiated. Cardiopulmonary data were collected before each electrical supramaximal stimulus during MAC(ISO+EPI) determinations. RESULTS: The mean (+/-SD) MAC(ISO) was 1.29 +/- 0.04%. The epidural administration of xylazine at doses of 0.1, 0.2, and 0.4 mg x kg(-1) decreased the MAC(ISO), respectively, by 8.4 +/- 2.4%, 21.7 +/- 4.9%, and 33.4 +/- 2.64%. Cardiopulmonary effects were limited. CONCLUSIONS AND CLINICAL RELEVANCE: Epidural administration of xylazine decreases the MAC(ISO) in a dose-dependent manner and is associated with few cardiopulmonary effects in anesthetized dogs.