Retrospective evaluation of the impact of hypoxemia during thoracic surgery in dogs on outcome: a multicenter analysis of 94 cases.

OBJECTIVE: To investigate the statistical association of severe intraoperative hypoxemia in thoracic surgery with mortality, postoperative hospitalization times and cost of care. STUDY DESIGN: Retrospective study. ANIMALS: Dogs that underwent thoracic surgery in three veterinary hospitals between October 1, 2018 and October 1, 2020. METHODS: Anesthesia and hospitalization records from 112 dogs were reviewed and 94 cases met inclusion criteria. Recorded data included signalment, disease etiology, pulmonary or extrapulmonary nature of disease, surgical procedure performed, episodes of severe intraoperative hypoxemia defined as a pulse oximetry reading (SpO2) <90% of 5 minutes or longer duration, survival to discharge, time from extubation to hospital discharge and total invoice cost for clinical visit. Dogs were divided into two groups, those that experienced severe hypoxemia (group A) and those in which SpO2 reading <90% was not observed throughout the procedure (group B). RESULTS: Group A had a greater risk of mortality (odds ratio 10.6, 95% confidence interval 1.9-106.7; p = 0.002), prolonged hospitalization (median 62 hours versus 46 hours; p = 0.035) and more expensive cost of care (median US$10,287 versus $8506; p = 0.056) than group B. No significant difference was found for the type of surgical procedure or pulmonary versus extrapulmonary nature of disease. CONCLUSIONS AND CLINICAL RELEVANCE: Severe intraoperative hypoxemia was statistically associated with an increased risk of mortality and longer postoperative hospitalization times. Although not achieving statistical significance, there was a trend toward increased costs to the client for animals with intraoperative hypoxemia.

Use of CO-oximetry to confirm carboxyhemoglobinemia in cats involved in secondary arson homicide.

The body of a deceased human and 4 deceased cats were found in a house while a fire was being extinguished. As a result of these findings, arson, homicide, and animal death investigations were opened. As part of the animal death investigation, all of the cats were submitted for veterinary forensic autopsies. All cats had soot on the fur and had soot deposits within the oral cavity, esophagus, and respiratory tract. Two cats had soot within the stomach. Cardiac blood was analyzed for carboxyhemoglobin using a CO-oximeter, and all cats had levels >65%. The cause of death was determined to be due to toxic smoke inhalation from the structure fire. Case findings support the potential use of CO-oximeter for determination of carboxyhemoglobin levels in cats and continued research in this area of forensic practice.

Evaluation of the performance of two new generation pulse oximeters in cats at different probe positions and under the influence of vasoconstriction.

OBJECTIVES: The aim of this study was to compare the failure rate of two new generation pulse oximeters at different probe positions, and with and without vasoconstriction, in anaesthetised cats. METHODS: This prospective clinical study included 103 cats in which the new generation pulse oximeters, the Rad-5 (Masimo) and EDAN H100N (EDAN), were evaluated. Premedication consisted of the vasoconstrictive drug combination butorphanol (0.2 mg/kg IV) and dexmedetomidine (5 µg/kg IV), or butorphanol only (0.2 mg/kg IV). Pulse oximeter failure rate at the tongue was compared between both groups. Pulse oximeter failure rate was also analysed at the alternative probe positions of the lip, pinna, knee fold and toe in the butorphanol group. Student's t-test, Wilcoxon matched pairs signed rank test, Mann-Whitney U-test, Friedman test and χ2 test were performed. A P value <0.05 was considered to be statistically significant. RESULTS: Overall failure to achieve an adequate signal was 37.6% with the Masimo and 48.0% with the EDAN pulse oximeter (P <0.0001). At the standard probe position on the tongue, the Masimo failed in 4.5%, while the EDAN failed in 35.3% (P <0.0001). Vasoactive premedication increased the failure rate for the Masimo from 3.8% to 5.2% (P = 0.3414) and for the EDAN from 22.4% to 49.0% (P <0.0001). At the alternative probe positions of the lip and knee fold, failure rates for the Masimo were lower (39.7% and 81.4%) than with the EDAN (52.6% and 94.4%; P = 0.0231 and P = 0.0005, respectively), while the Masimo failed more often at the pinna (63.5%) than the EDAN (47.4%; P = 0.0044). At the alternative probe position of the toe, the failure rate for the Masimo (32.7%) was not different from the EDAN (38.5%; P = 0.7547). CONCLUSIONS AND RELEVANCE: The Masimo pulse oximeter had lower signal failure rates at the standard probe position on the tongue and at 2/4 alternative probe positions. The standard probe position on the tongue had the lowest failure rate for both devices. Dexmedetomidine-induced vasoconstriction increased the failure rate for the EDAN but not for the Masimo pulse oximeter.

Comparison of venous hemoglobin saturation measurements obtained by in vivo oximetry and calculated from blood gas analysis in critically ill dogs.

OBJECTIVE: To compare in vivo central venous hemoglobin saturation measurement (ScvO2 ) using a fiber optic catheter with saturation calculated from blood gas analysis in critically ill dogs. DESIGN: Prospective observational study. SETTING: University veterinary teaching hospital intensive care unit. ANIMALS: A convenience sample of 20 dogs with severe illness. INTERVENTIONS: Dogs were instrumented with either a central venous catheter with an integrated fiber optic cable or a conventional catheter with a fiber optic probe inserted through its distal port. Baseline saturation was measured with the fiber optic system (FSO2 ), then monitored continuously. Central venous blood was collected for analysis and FSO2 was recorded by the principal investigator (PI) or nursing staff participating in data collection (staff) at baseline and at 1, 2, 3, and 6 hours. Hemoglobin oxygen saturation (SO2 ) values calculated using human Bohr coefficients were taken directly from the analyzer (GPSO2 ), and were also calculated using temperature-correction and canine Bohr coefficients (RSO2 ). MEASUREMENTS AND MAIN RESULTS: Ninety-seven paired measurements from 20 dogs were analyzed. FSO2 obtained by the PI (n = 41) had better agreement with both GPSO2 (concordance correlation coefficient ρc = 0.926 vs 0.5562) and RSO2 (ρc = 0.75 for PI vs 0.54) than did staff (n = 56). RSO2 values were always smaller than GPSO2 . FSO2 - GPSO2 differences were smaller when measurements were collected by the PI versus Staff (mean difference 0.21 vs -6.6, respectively, P < 0.02). Thirty-six of 41 FSO2 values obtained by PI were within 5% of GPSO2 . CONCLUSIONS: Concordance between FSO2 and either calculation method was low, but was better when performed by PI. The larger difference between methods when using RSO2 suggests a positive bias by FSO2 . Difficulty obtaining stable measurements may have contributed to the poor concordance between methods within Staff.

Developing a modified Apgar scoring system for newborn lambs.

The Apgar (appearance, pulse, grimace, attitude, respiration) score is an accepted method for assessing newborn viability in humans and domestic animals. The purpose of this research was to modify an existing Apgar scoring system for lambs and compare Apgar score with litter size and birth order, as well as time-to-stand and time-to-suckle. Polypay lambs (n = 75) delivered naturally were used for this study. Pulse (<100 bpm = 0; 100-175 bpm = 1; >175 bpm = 2) and respiration (<45% SpO2 = 0; 45-65% SpO2 = 1; >65% SpO2 = 2) were measured with a pulse oximeter attached to the lamb's ear. Appearance, grimace, and attitude were assessed using mucous membrane color (cyanotic = 0; pale = 1; pink = 2); response to nose stimulation (no response = 0; moves head slightly = 1; shakes head = 2); and response to rump stimulation (no movement = 0; moves but no attempt to stand = 1; attempts to stand = 2), respectively. The Apgar score was measured within 5 min of birth (T0), 15 min (T15) and 60 min (T60) after birth. The time-to-stand and time-to-suckle were recorded and compared to Apgar scores. Apgar scores did not differ by litter size or birth order. There were no significant correlations between the Apgar scores and time-to-stand. There was a moderate positive correlation between attitude and time-to-suckle at T0 (R2 = 0.467), which may affect the ingestion of adequate colostrum in a timely manner. Producers may choose to consider using Apgar scoring so that assistance can be provided to lambs before serious complications arise.

Cardiorespiratory effects of a 7° reverse Trendelenburg position in anaesthetized horses: a randomized clinical trial.

OBJECTIVE: To evaluate the cardiorespiratory effects of a 7° reverse Trendelenburg position (RTP) in anaesthetized horses. STUDY DESIGN: Randomized, non-blinded clinical trial. ANIMALS: A total of 125 horses undergoing elective surgery in dorsal recumbency. METHODS: Horses were allocated to one of three weight classes and assigned to be positioned either on a horizontal table or on a table in 7° RTP, according to a randomized block design. In all horses, anaesthesia was maintained with isoflurane in oxygen and a constant rate infusion of romifidine. All horses were mechanically ventilated throughout anaesthesia, and routine cardiovascular monitoring and arterial blood gas analysis were performed at 15-minute intervals and relevant variables calculated. Data from the first 60 minutes of anaesthesia were compared between both positions using a mixed model analysis of variance. RESULTS: A significant interaction was found between position and weight class for the alveolar to arterial oxygen tension gradient and F-shunt: these variables were lower in RTP than in horizontal position in the two lowest weight classes and vice versa in the highest weight class. Arterial oxygen tension and oxygenation indices were significantly worse in the horses in the higher weight classes. CONCLUSIONS AND CLINICAL RELEVANCE: A 7° RTP did not result in clinically relevant changes in gas exchange or cardiovascular function. Horses with a higher body weight are at increased risk for hypoxaemia during anaesthesia in dorsal recumbency.

Desaturation times between dogs preoxygenated via face mask or flow-by technique before induction of anesthesia.

OBJECTIVE: To compare time to desaturation after induction of anesthesia following administration of oxygen via face mask or flow-by for 3 minutes. STUDY DESIGN: Randomized crossover study. ANIMALS: A group of six healthy adult dogs weighing 15.0 ± 3.4 kg. METHODS: Dogs were anesthetized twice separated by 14 days. Intramuscular administration of dexmedetomidine (4 µg kg-1), acepromazine (0.01 mg kg-1) and butorphanol (0.2 mg kg-1) provided sedation for percutaneous insertion of a catheter into the tracheal lumen. The tip was advanced to the thoracic inlet and position confirmed using fluoroscopy. Using a sample aspiration rate 200 mL minute-1, inspired (FIO2) and end-tidal oxygen (Fe'O2) were measured. Oxygen (100 mL kg-1 minute-1) was delivered into a circle delivery system and administered to the dog for 3 minutes via face mask or flow-by from the circle Y-piece 2.5 cm from the nares. Then, propofol was administered to induce anesthesia and apnea. A pulse oximeter (lingual probe) measured hemoglobin saturation (SpO2). At SpO2 90% (desaturation point), an endotracheal tube was inserted to allow administration of oxygen and artificial ventilation. Arterial blood and data were collected at baseline (before oxygen administration), 5 seconds after induction of anesthesia, and every 30 seconds until the desaturation point was reached. Data were analyzed using an unpaired and paired t test with (p < 0.05). RESULTS: FIO2, Fe'O2 and PaO2 (mean ± standard deviation) were significantly higher after mask preoxygenation [89.7 ± 5.5%, 83.0 ± 7.6% and 394 ± 112 mmHg (52.4 ± 14.9 kPa)] compared with flow-by [30.0 ± 5.4%, 22.7 ± 3.8% and 133 ± 22 mmHg (17.7 ± 2.9 kPa)], respectively. Time to desaturation was significantly longer after mask treatment compared with flow-by (187 ± 67 versus 66 ± 17 seconds). CONCLUSIONS AND CLINICAL RELEVANCE: Mask preoxygenation provided longer time to desaturation compared with the flow-by technique tested.

Validation of a Pulse Oximetry System for High-Altitude Waterfowl by Examining the Hypoxia Responses of the Andean Goose (Chloephaga melanoptera).

Hypoxia at high altitudes constrains O2 supply to support metabolism, thermoregulation in the cold, and exercise. High-altitude natives that somehow overcome this challenge-who live, reproduce, and sometimes perform impressive feats of exercise at high altitudes-are a powerful group in which to study the evolution of physiological systems underlying hypoxia resistance. Here, we sought to determine whether a common pulse oximetry system for rodents (MouseOx Plus) can be used reliably in studies of high-altitude birds by examining the hypoxia responses of the Andean goose. We compared concurrent measurements of heart rate obtained using pulse oximetry versus electrocardiography. We also compared our measurements of peripheral arterial O2 saturation (SaO2) in uncannulated birds with published data collected from blood samples in birds that were surgically implanted arterial cannulae. Responses to acute hypoxia were measured during stepwise reductions in inspired partial pressure of O2. Andean geese exhibited very modest breathing and heart rate responses to hypoxia but were nevertheless able to maintain normal O2 consumption rates during severe hypoxia exposure down to 5 kPa O2. There were some minor quantitative differences between uncannulated and cannulated birds, which suggest that surgery, cannulation, and/or other sources of variability between studies had modest effects on the hypoxic ventilatory response, heart rate, blood hemoglobin, and hematocrit. Nevertheless, measurements of heart rate and SaO2 by pulse oximetry had small standard errors and were generally concordant and well correlated with measurements using other techniques. We conclude that the MouseOx Plus pulse oximetry system can be a valuable tool for studying the cardiorespiratory physiology of waterfowl without the deleterious effects of surgery/cannulation.

Effects of positive end-expiratory pressure and 30% inspired oxygen on pulmonary mechanics and atelectasis in cats undergoing non-bronchoscopic bronchoalveolar lavage.

Objectives The objective of this study was to determine if modification of inspired oxygen concentration or positive end-expiratory pressure (PEEP) would alter bronchoalveolar lavage (BAL)-induced changes in pulmonary mechanics or atelectasis, as measured using ventilator-acquired pulmonary mechanics and thoracic CT. Methods Six experimentally asthmatic cats underwent anesthesia and non-bronchoscopic BAL, each under four randomized treatment conditions: 100% oxygen, zero PEEP; 30% oxygen, zero PEEP; 100% oxygen, PEEP 2 cmH2O; and 30% oxygen, PEEP 2 cmH2O. Pulse oximetry was used to estimate oxygen saturation (SpO2). Ventilator-acquired pulmonary mechanics and thoracic CT scans were collected prior to BAL and at 1, 5 and 15 mins post-BAL. Results While receiving 100% oxygen, no cat had SpO2 <91%. Some cats receiving 30% oxygen had decreased saturation immediately post-BAL (mean ± SD 70.8 ± 31%), but 6/8 of these had SpO2 >90% by 1 min later. There was a significant increase in airway resistance and a decrease in lung compliance following BAL, but there was no significant difference between treatment groups. Cats receiving no PEEP and 30% oxygen conserved better aeration of the lung parenchyma in BAL-sampled areas than those receiving no PEEP and 100% oxygen. Conclusions and relevance Alterations in pulmonary mechanics or atelectasis may not be reflected by SpO2 following BAL. The use of 30% inspired oxygen concentration failed to show any significant improvement in pulmonary mechanics but did diminish atelectasis. In some cats, it was also associated with desaturation of hemoglobin. The use of PEEP in this study did not show any effect on our outcome parameters. Further studies using higher PEEP (5-10 cmH2O) and intermediate inspired oxygen concentration (40-60%) are warranted to determine if they would confer clinical benefit in cats undergoing diagnostic BAL.

Use of a perfusion index to confirm the presence of sciatic nerve blockade in dogs.

OBJECTIVES: To evaluate perfusion index (PI) as a determinant of regional nerve block success following sciatic nerve blockade with bupivacaine in dogs undergoing stifle surgery. STUDY DESIGN: Prospective clinical trial. ANIMALS: Ten adult dogs, aged 5.6 ± 2.6 years and weighing 36.9 ± 16.8 kg, undergoing a tibial plateau leveling osteotomy. METHODS: Dogs were premedicated with acepromazine (0.03 mg kg-1 ) and hydromorphone (0.1 mg kg-1 ) intramuscularly, and anesthetized with propofol (up to 4 mg kg-1 ) intravenously and isoflurane in oxygen. An ultrasound-guided femoral and sciatic (F+S) nerve block was performed on the surgical limb with bupivacaine (0.75%), 0.2 mL kg-1 at the femoral site and 0.3 mL kg-1 at the sciatic site, with a maximum volume of 10 mL per site. Physiological variables were recorded every 5 minutes throughout anesthesia. A pulse co-oximeter probe was placed between the third and fourth digits of both pelvic limbs, and the PI was recorded 5 minutes before infiltration with bupivacaine, immediately afterwards, and every 5 minutes for 30 minutes. Motor nerve conduction velocity (MNCV) of the sciatic nerve was performed on the surgical limb 5 minutes before and 20 minutes after bupivacaine administration to confirm nerve block. RESULTS: The PI of the surgical limb was significantly greater than the contralateral pelvic limb at 10 minutes (p = 0.03) and 15 minutes (p < 0.01) after F+S nerve blockade. The MNCV performed after sciatic nerve blockade revealed a functional motor blockade for all dogs. There were no significant changes in physiological variables. CONCLUSIONS AND CLINICAL RELEVANCE: The PI provided a reliable indication of successful sciatic nerve blockade in the clinical patients in this study. No increase in the PI by 15 minutes after bupivacaine administration around the sciatic nerve could indicate partial or total failure of anesthetic blockade.

Multicentre, randomised clinical trial evaluating the efficacy and safety of alfaxalone administered to bitches for induction of anaesthesia prior to caesarean section.

OBJECTIVE: To determine the clinical safety and efficacy of alfaxalone in bitches undergoing caesarean section (CS) and their puppies when it is administered for induction of anaesthesia followed by maintenance with isoflurane and oxygen and in conjunction with perioperative pharmaceuticals. DESIGN: A multicentre, randomised, positive-controlled clinical study. METHODS: A total of 74 bitches were enrolled in the study with 48/74 (65%) and 26/74 (35%) receiving alfaxalone and propofol, respectively, for induction of anaesthesia. Bitches were examined prior to induction and monitored during induction, surgery and recovery. Assessments were made for quality of induction, maintenance and recovery from anaesthesia. Assessments were made on pup viability for suction, dorsal flexion, withdrawal and anogenital reflexes. RESULTS: Of the 48 bitches receiving alfaxalone, 47 (98%) and 39 (81%) scored a top score of excellent for induction and anaesthesia effectiveness, respectively. For the same parameters with propofol in 26 bitches, 23 (88%) and 17 (65%) scored excellent. Average scores for recovery were not different between the two treatment groups with alfaxalone 46/48 (96%) and 25/26 (96%) of propofol induced bitches scoring a good or excellent rating. Bitches tolerated a number of concurrent medications throughout the peri-operative period. No bitch fatalities were observed in this study. There were no statistically significant differences between treatment groups for the puppy variables. Live puppies born by CS to bitches having been administered alfaxalone or propofol had similar survival rates 24 h after birth (i.e. 205/213 (96%) and 124/131 (95%), respectively). CONCLUSION: This study confirms the safety and efficacy of alfaxalone for the purpose of anaesthetic induction for CS in the bitch. In addition, alfaxalone had a negligible effect on the neonate with >95% of puppies alive 24 h after the bitch had recovered from anaesthesia with alfaxalone induction.

Effects of pneumoperitoneum induced at various pressures on cardiorespiratory function and working space during laparoscopy in cats.

OBJECTIVE: To evaluate the effect of pneumoperitoneum on cardiorespiratory variables and working space during experimental induction of 3 intra-abdominal pressures (IAPs) in cats. ANIMALS: 6 healthy young adult neutered male domestic shorthair cats. PROCEDURES: All cats were anesthetized through use of a standardized protocol. A catheter was placed in the right femoral artery for blood pressure and blood gas monitoring. A thermodilution catheter was placed in the right jugular vein via fluoroscopic guidance. Cardiopulmonary variables were measured before (baseline) and 2 and 30 minutes after initiation of pneumoperitoneum at IAPs of 4, 8, and 15 mm Hg; these were created through the use of a mechanical insufflator. At each IAP, abdominal dimensions (height, width, and circumference) were measured at a standardized location. RESULTS: At 4 mm Hg and 8 mm Hg IAP, no clinically important changes were identified in cardiorespiratory values. Heart rate, cardiac index, and stroke volume index remained unchanged throughout the study at all IAPs. Mean arterial blood pressure began to increase at 8 mm Hg and was significantly higher, compared with baseline, at both time points at 15 mm Hg. At 15 mm Hg, Paco2 was significantly higher and cats were more acidotic than at baseline. Working space was subjectively greater at 8 mm Hg than at 4 mm Hg IAP; however, at 15 mm Hg, no clinically important enlargement of the working space was identified, compared with at 8 mm Hg. CONCLUSIONS AND CLINICAL RELEVANCE: Values of cardiopulmonary variables were largely unchanged by induction of pneumoperitoneum in healthy cats up to an IAP of 8 mm Hg, and no clinically important increases in working space were evident at an IAP of 15 versus 8 mm Hg. These findings provide little justification for use of IAPs > 8 mm Hg in healthy cats undergoing laparoscopic procedures; however, whether the situation is similar in diseased or elderly cats remains to be determined.

Use of arterial blood gas analysis as a superior method for evaluating respiratory function in pet rabbits (Oryctolagus cuniculus).

A retrospective study compared invasive (arterial blood gas analysis) and non-invasive (capnography and pulse oximetry) methods of monitoring respiratory function in conscious rabbits. Arterial samples from 50 healthy dwarf lop rabbits, presenting for routine surgical neutering, were analysed on a point-of-care blood gas analysis machine. Reference intervals were obtained for pH (7.35-7.54), PaCO2 (mm Hg) (25.29-40.37), PaO2 (mm Hg) (50.3-98.2), base excess (mmol/l) (6.7-6.5), HCO3 (mmol/l) (17.96-29.41), TCO2 (mmol/l) (18.9-30.5). SaO2 (per cent) (88.8-98.0), Na (mmol/l) (137.6-145.2), K (mmol/l) (3.28-4.87), iCal (mmol/l) (1.64-1.94), glucose (mmol/l) (6.23-10.53), haematocrit (per cent) (23.3-40.2) and haemoglobin (mg/dl) (7.91-13.63). Pulse oximetry (SPO2) and capnography (ETCO2) readings were taken concurrently. There was no statistically significant relationship between SPO2 and SaO2 with a mean difference between SPO2 and SaO2 of 8.22 per cent. There was a statistically significant relationship between ETCO2 vs PaCO2, but a wide range of ETCO2 values were observed for a given PaCO2. The mean difference between these was 16.16 mm Hg. The study has provided reference intervals for arterial blood gas analysis in rabbits and demonstrated that capnography and pulse oximetry readings should not be relied upon in conscious rabbits as a guide to ventilation and oxygenation.

Evaluation of Masimo signal extraction technology pulse oximetry in anaesthetized pregnant sheep.

OBJECTIVE: Evaluation of the accuracy of Masimo signal extraction technology (SET) pulse oximetry in anaesthetized late gestational pregnant sheep. STUDY DESIGN: Prospective experimental study. ANIMALS: Seventeen pregnant Merino ewes. METHODS: Animals included in study were late gestation ewes undergoing general anaesthesia for Caesarean delivery or foetal surgery in a medical research laboratory. Masimo Radical-7 pulse oximetry (SpO(2) ) measurements were compared to co-oximetry (SaO(2) ) measurements from arterial blood gas analyses. The failure rate of the pulse oximeter was calculated. Accuracy was assessed by Bland & Altman's (2007) limits of agreement method. The effect of mean arterial blood pressure (MAP), perfusion index (PI) and haemoglobin (Hb) concentration on accuracy were assessed by regression analysis. RESULTS: Forty arterial blood samples paired with SpO(2) and blood pressure measurements were obtained. SpO(2) ranged from 42 to 99% and SaO(2) from 43.7 to 99.9%. MAP ranged from 24 to 82 mmHg, PI from 0.1 to 1.56 and Hb concentration from 71 to 114 g L(-1) . Masimo pulse oximetry measurements tended to underestimate oxyhaemoglobin saturation compared to co-oximetry with a bias (mean difference) of -2% and precision (standard deviation of the differences) of 6%. Accuracy appeared to decrease when SpO(2) was <75%, however numbers were too small for statistical comparisons. Hb concentration and PI had no significant effect on accuracy, whereas MAP was negatively correlated with SpO(2) bias. CONCLUSIONS AND CLINICAL RELEVANCE: Masimo SET pulse oximetry can provide reliable and continuous monitoring of arterial oxyhaemoglobin saturation in anaesthetized pregnant sheep during clinically relevant levels of cardiopulmonary dysfunction. Further work is needed to assess pulse oximeter function during extreme hypotension and hypoxaemia.

Evaluation of the isoflurane-sparing effects of lidocaine infusion during umbilical surgery in calves.

OBJECTIVE: To evaluate the isoflurane-sparing effects of lidocaine administered by constant rate infusion (CRI) during umbilical surgery in calves. STUDY DESIGN: Randomized 'blinded' prospective clinical study. ANIMALS: Thirty calves (mean 4.7 ± SD 2.5 weeks old) undergoing umbilical surgery. METHODS: After premedication with xylazine (0.1 mg kg(-1) , IM), anaesthesia was induced with ketamine (4 mg kg(-1) , IV) and maintained with isoflurane in O(2) administered through a circle breathing system. The calves were assigned randomly to receive a bolus of 2 mg kg(-1) lidocaine IV after induction of anaesthesia, followed by CRI of 50 µg kg(-1) minute(-1) (group L, n=15) or a bolus and CRI of 0.9% sodium chloride (NaCl, group S, n=15). End-tidal isoflurane was adjusted to achieve adequate depth of anaesthesia. Heart rate, direct arterial blood pressure and body temperature were measured intraoperatively. Groups were compared by t- tests, anova or Mann-Whitney rank sum test as appropriate. RESULTS: The end-tidal concentration of isoflurane (median, IQR) was significantly lower in group L [1.0% (0.94-1.1)] compared to group S [1.2% (1.1-1.5)], indicating a 16.7% reduction in anaesthetic requirement during lidocaine CRI. Cardiopulmonary parameters and recovery times did not differ significantly between groups. CONCLUSION AND CLINICAL RELEVANCE: Lidocaine CRI may be used as a supplement to inhalation anaesthesia during umbilical surgery in calves in countries where such a protocol would be within the legal requirements for veterinary use in food animals. This study did not show any measurable benefit to the calves other than a reduction in isoflurane requirement.

Respiratory rates and arterial blood-gas tensions in healthy rabbits given buprenorphine, butorphanol, midazolam, or their combinations.

The objective of this study was to evaluate the respiratory effects of buprenorphine, butorphanol, midazolam, and their combinations in healthy conscious rabbits. Six adult female New Zealand white rabbits were anesthetized briefly with isoflurane by mask to allow placement of a catheter into the central ear artery. After a 60-min recovery period, a baseline arterial sample was obtained. Animals then were injected intramuscularly with either 0.9% NaCl (1 mL), buprenorphine (0.03 mg/kg), butorphanol (0.3 mg/kg), midazolam (2 mg/kg), buprenorphine + midazolam (0.03 mg/kg, 2 mg/kg), or butorphanol + midazolam (0.3 mg/kg, 2 mg/kg). Arterial blood gases were evaluated at 30, 60, 90, 120, 180, 240, and 360 min after drug administration. All drug treatments caused significant decreases in respiratory rate, compared with saline. Buprenorphine and the combinations of midazolam-butorphanol and midazolam-buprenorphine resulted in statistically significant decreases in pO(2). No significant changes in pCO(2) pressure were recorded for any treatment. Increases in blood pH were associated with administration of butorphanol, midazolam, and the combinations of midazolam-butorphanol and midazolam-buprenorphine. In light of these results, buprenorphine and the combinations of midazolam-buprenorphine and midazolam-butorphanol result in statistically significant hypoxemia in rabbits that breathe room air. The degree of hypoxemia is of questionable clinical importance in these healthy subjects. Hypoxemia resulting from these drug combinations may be amplified in rabbits with underlying pulmonary or systemic disease.

Blood gas analysis and cooximetry in retired racing Greyhounds.

OBJECTIVE: The purposes of this study were to evaluate the oxygen affinity of hemoglobin (Hb) in healthy retired racing Greyhounds via cooximetry, and to establish reference intervals for blood gases and cooximetry in this breed. DESIGN: Prospective clinical study. SETTING: University Teaching Hospital. ANIMALS: Fifty-seven Greyhounds and 30 non-Greyhound dogs. INTERVENTIONS: Venous blood samples were collected from the jugular vein and placed into heparinized tubes. The samples were analyzed within 30 minutes of collection using a blood gas analyzer equipped with a cooximeter. MEASUREMENTS AND MAIN RESULTS: Greyhounds had significantly higher pH, PO(2) , oxygen saturation, oxyhemoglobin, total Hb, oxygen content, and oxygen capacity and significantly lower deoxyhemoglobin and P(50) when compared with non-Greyhound dogs. CONCLUSION: These findings support the fact that this breed is able to carry a higher concentration of total oxygen in the blood. As reported previously, this breed also has lower P(50) and, therefore, high oxygen affinity. In light of recent findings suggesting that in certain tissues a high affinity for oxygen is beneficial, this adaptation may be of benefit during strenuous exercise.

Influência do alprostadil na cicatrização da anastomose de esôfago cervical: estudo em cães / Alprostadil and it's healing on cervical esophageal anastomosis in dogs

Nas operações do esôfago deiscências nas anastomoses correpondem à graves complicações. Anastomoses esôfago-esofágicas cervicais demonstram altas taxas de deiscências. Muitos fatores podem estar envolvidos nelas tais como a tensão na anastomose, distribuição do suprimento sanguíneo, trauma local, obstrução e infecção...

Cervical esophageal anastomosis has high dehiscences rates and mortality. Many factors can be involved on it, such as anastomotic tension, impared blood supply, local trauma, blockage and infection...

Examination of potential methods to predict pulmonary arterial pressure score in yearling beef cattle.

Susceptibility of beef cattle to high altitude disease (HAD) is of major importance to economic and genetic selection on high elevation ranches. However, currently the best indicator of HAD susceptibility is the pulmonary arterial pressure (PAP) test, a test with high cost and invasive nature. Therefore, 2 experiments were undertaken to determine whether emerging technologies that predict blood components could be used to predict the PAP score in yearling Angus cattle. In Exp. 1, 39 yearling Angus bulls were used to determine if a relationship existed between PAP score and 10 blood components provided by a hemogram using whole blood or oxygen saturation as predicted by pulse oximetry in nonanesthetized cattle measured rectally or orally. Three of the hemogram values (packed cell volume, hemoglobin concentration, and red cell distribution width) were correlated (P < 0.10) with the PAP score. Prediction equations for PAP score were generated using the hemogram values and resulted in R2 values of 0.375 and 0.305 for the regression model using all of values and the best 2-variable model, respectively. Pulse oximetry was able to provide oxygen saturation predictions rectally or orally; however, the predicted values were not correlated with the PAP score (P > 0.10) or with each other (P > 0.10). In Exp. 2, 84 yearling Angus cattle (62 bulls, 22 heifers) were used to evaluate the ability of a portable clinical analyzer to predict the PAP score using 11 blood components from a sample of whole blood evaluated at the processing chute. The portable clinical analyzer was able to provide values for all of the 11 blood components; however, none of the predicted values were correlated with the PAP score (P > 0.10). In these preliminary experiments, 3 blood component values provided via the hemogram were the only variables both correlated with the PAP score and able to contribute to the development of a useful PAP prediction equation that could reduce the cost of traditional measures of HAD susceptibility. Future research is needed to determine whether additional blood components or emerging blood analysis technologies are able to accurately predict the PAP score in beef cattle.