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1.
ObjectiveTo evaluate agreement between end-tidal carbon dioxide (Pe′CO2) and PaCO2 with sidestream and mainstream capnometers in mechanically ventilated anesthetized rabbits, with two ventilatory strategies.Study designProspective experimental study.AnimalsA total of 10 New Zealand White rabbits weighing 3.6 ± 0.3 kg (mean ± standard deviation).MethodsRabbits anesthetized with sevoflurane were intubated with an uncuffed endotracheal tube (3.0 mm internal diameter) and adequate seal. For Pe′CO2, the sidestream capnometer sampling adapter or the mainstream capnometer was placed between the endotracheal tube and Bain breathing system (1.5 L minute–1 oxygen). PaCO2 was obtained from arterial blood collected every 5 minutes. A time-cycled ventilator delivered an inspiratory time of 1 second and 12 or 20 breaths minute–1. Peak inspiratory pressure was initially set to achieve Pe′CO2 normocapnia of 35–45 mmHg (4.6–6.0 kPa). A total of five paired Pe′CO2 and PaCO2 measurements were obtained with each ventilation mode for each capnometer. Anesthetic episodes were separated by 7 days. Agreement was assessed using Bland-Altman analysis and linear mixed models; p < 0.05.ResultsThere were 90 and 83 pairs for the mainstream and sidestream capnometers, respectively. The mainstream capnometer underestimated PaCO2 by 12.6 ± 2.9 mmHg (proportional bias 0.44 ± 0.06 mmHg per 1 mmHg PaCO2 increase). With the sidestream capnometer, ventilation mode had a significant effect on Pe′CO2. At 12 breaths minute–1, Pe′CO2 underestimated PaCO2 by 23.9 ± 8.2 mmHg (proportional bias: 0.81 ± 0.18 mmHg per 1 mmHg PaCO2 increase). At 20 breaths minute–1, Pe′CO2 underestimated PaCO2 by 38.8 ± 5.0 mmHg (proportional bias 1.13 ± 0.10 mmHg per 1 mmHg PaCO2 increase).Conclusions and clinical relevanceBoth capnometers underestimated PaCO2. The sidestream capnometer underestimated PaCO2 more than the mainstream capnometer, and was affected by ventilation mode.  相似文献   

2.
ObjectiveTo evaluate the fresh gas flow (FGF) rate requirements for the Humphrey ADE semi-closed breathing system in the Mapleson A mode; to determine the FGF at which rebreathing occurs, and compare the efficiency of this system to the Bain (Mapleson D) system in spontaneously breathing cats and small dogs.Study DesignProspective clinical study.AnimalsTwenty-five healthy (ASA score I or II) client-owned cats and dogs (mean ± SD age 4.7 ± 5.0 years, and body weight 5.64 ± 3.26 kg) undergoing elective surgery or minor procedures.MethodsAnaesthesia was maintained with isoflurane delivered via the Humphrey ADE system in the A mode using an oxygen FGF of 100 mL kg−1 minute−1. The FGF was then reduced incrementally by 5–10 mL kg−1minute−1 at approximately five-minute intervals, until rebreathing (inspired CO2 >5 mmHg (0.7 kPa)) was observed, after which flow rates were increased. In six animals, once the minimum FGF at which rebreathing occurred was found, the breathing system was changed to the Bain, and the effects of this FGF delivery examined, before FGF was increased.ResultsRebreathing did not occur at the FGF recommended by the manufacturer for the ADE. The mean ± SD FGF that resulted in rebreathing was 60 ± 20 mL kg−1minute−1. The mean minimum FGF at which rebreathing did not occur with the ADE was 87 ± 39 mL kg−1minute−1. This FGF resulted in significant rebreathing (inspired CO2 8.8 ± 2.6 mmHg (1.2 ± 0.3 kPa)) on the Bain system.ConclusionsThe FGF rates recommended for the Humphrey ADE are adequate to prevent rebreathing in spontaneously breathing cats and dogs <15 kg.Clinical relevanceThe Humphrey ADE system used in the A mode is a more efficient alternative to the Bain system, for maintenance of gaseous anaesthesia in spontaneously breathing cats and small dogs.  相似文献   

3.
ObjectiveTo compare the accuracy of transcutaneous (tc) to arterial partial pressure of carbon dioxide (PaCO2) and partial pressure of oxygen (PaO2) in anesthetized rabbits.Study designProspective, randomized, experimental study.AnimalsEight healthy adult female New Zealand white rabbits weighing 4.05 ± 0.30 kg.MethodsIsoflurane anesthetized rabbits received six treatments in random order; PaCO2 < 35, 35-45, and >45 mmHg and PaO2 < 80, 100-200, >200 mmHg. Arterial and transcutaneous measurements were taken after 15 minutes of stabilization at each condition. Linear regression, correlation and Bland-Altman analysis were performed to compare PtcCO2 to PaCO2 and PtcO2 to PaO2.ResultsOver a range of measured PaCO2 values from 21 to 67 mmHg (n = 24) mean bias for PtcCO2 was -1 mmHg and the 95% limits of agreement were -7 to 5 mmHg. The correlation between PtcCO2 and PaCO2 was strong with R2 value of 0.9454. Over the entire range of measured PaO2 values (46-508 mmHg) mean bias for PtcO2 was -61 mmHg and the 95% limits of agreement were -226 to 104 mmHg. Correlation was poor with R2 = 0.5969. Comparing PtcO2 to PaO2 over a narrower range [PaO2 < 150 mmHg (n = 13)] improved the correlation, with an R2 value of 0.8518, mean bias of -7 mmHg and 95% limits of agreement from -33 to 19 mmHg.Conclusions and clinical relevanceIn healthy anesthetized rabbits, PtcCO2 closely approximated PaCO2. In contrast PtcO2 underestimated PaO2, particularly at high values. The PtcCO2 sensor may be a useful noninvasive way to assess adequacy of ventilation in anesthetized rabbits.  相似文献   

4.
ObjectiveTo investigate the relationship between oxygen administration and ventilation in rabbits administered intramuscular alfaxalone–dexmedetomidine–midazolam.Study designProspective, randomized, blinded study.AnimalsA total of 25 New Zealand White rabbits, weighing 3.1–5.9 kg and aged 1 year.MethodsRabbits were anesthetized with intramuscular alfaxalone (4 mg kg–1), dexmedetomidine (0.1 mg kg–1) and midazolam (0.2 mg kg–1) and randomized to wait 5 (n = 8) or 10 (n = 8) minutes between drug injection and oxygen (100%) administration (facemask, 1 L minute–1). A control group (n = 9) was administered medical air 10 minutes after drug injection. Immediately before (PREoxy/air5/10) and 2 minutes after oxygen or medical air (POSToxy/air5/10), respiratory rate (fR), pH, PaCO2, PaO2, bicarbonate and base excess were recorded by an investigator blinded to treatment allocation. Data [median (range)] were analyzed with Wilcoxon, Mann–Whitney U and Kruskal–Wallis tests and p < 0.05 considered significant.ResultsHypoxemia (PaO2 < 88 mmHg, 11.7 kPa) was observed at all PRE times: PREoxy5 [71 (61–81) mmHg, 9.5 (8.1–10.8) kPa], PREoxy10 [58 (36–80) mmHg, 7.7 (4.8–10.7) kPa] and PREair10 [48 (32–64) mmHg, 6.4 (4.3–8.5) kPa]. Hypoxemia persisted when breathing air: POSTair10 [49 (33–66) mmHg, 6.5 (4.4–8.8) kPa]. Oxygen administration corrected hypoxemia but was associated with decreased fR (>70%; p = 0.016, both groups) and hypercapnia (p = 0.016, both groups). Two rabbits (one per oxygen treatment group) were apneic (no thoracic movements for 2.0–2.5 minutes) following oxygen administration. fR was unchanged when breathing air (p = 0.5). PaCO2 was higher when breathing oxygen than air (p < 0.001).Conclusions and clinical relevanceEarly oxygen administration resolved anesthesia-induced hypoxemia; however, fR decreased and PaCO2 increased indicating that hypoxemic respiratory drive is an important contributor to ventilation using the studied drug combination.  相似文献   

5.
ObjectiveTo characterize the impact of mechanical positive pressure ventilation on heart rate (HR), arterial blood pressure, blood gases, lactate, glucose, sodium, potassium and calcium concentrations in rattlesnakes during anesthesia and the subsequent recovery period.Study designProspective, randomized trial.AnimalsTwenty one fasted adult South American rattlesnakes (Crotalus durissus terrificus).MethodsSnakes were anesthetized with propofol (15 mg kg−1) intravenously, endotracheally intubated and assigned to one of four ventilation regimens: Spontaneous ventilation, or mechanical ventilation at a tidal volume of 30 mL kg−1 at 1 breath every 90 seconds, 5 breaths minute−1, or 15 breaths minute−1. Arterial blood was collected from indwelling catheters at 30, 40, and 60 minutes and 2, 6, and 24 hours following induction of anesthesia and analyzed for pH, PaO2, PaCO2, and selected variables. Mean arterial blood pressure (MAP) and HR were recorded at 30, 40, 60 minutes and 24 hours.ResultsSpontaneous ventilation and 1 breath every 90 seconds resulted in a mild hypercapnia (PaCO2 22.4 ± 4.3 mmHg [3.0 ± 0.6 kPa] and 24.5 ± 1.6 mmHg [3.3 ± 0.2 kPa], respectively), 5 breaths minute−1 resulted in normocapnia (14.2 ± 2.7 mmHg [1.9 ± 0.4 kPa]), while 15 breaths minute−1 caused marked hypocapnia (8.2 ± 2.5 mmHg [1.1 ± 0.3 kPa]). Following recovery, blood gases of the four groups were similar from 2 hours. Anesthesia, independent of ventilation was associated with significantly elevated glucose, lactate and potassium concentrations compared to values at 24 hours (p < 0.0001). MAP increased significantly with increasing ventilation frequency (p < 0.001). HR did not vary among regimens.Conclusions and clinical relevanceMechanical ventilation had a profound impact on blood gases and blood pressure. The results support the use of mechanical ventilation with a frequency of 1–2 breaths minute−1 at a tidal volume of 30 mL kg−1 during anesthesia in fasted snakes.  相似文献   

6.
ObjectiveTo compare oxygenation and ventilation in white-tailed deer (Odocoileus virginianus) anesthetized with two treatments with and without oxygen supplementation.Study designRandomized, blinded, crossover study.AnimalsA total of eight healthy adult white-tailed deer weighing 49–62 kg.MethodsEach deer was anesthetized twice intramuscularly: 1) treatment XK, xylazine (2 mg kg–1) and ketamine (6 mg kg–1) and 2) treatment XTZ, xylazine (2 mg kg–1) and tiletamine–zolazepam (4 mg kg–1). With the deer in sternal position, arterial and venous blood was collected before and at 30 minutes during administration of oxygen at 1 L minute–1 through a face mask. PaO2 and heart rate (HR) were compared using two-way repeated measures anova. pH, PaCO2 and lactate concentration were analyzed using mixed-effects linear models, p < 0.05.ResultsWhen breathing air, PaO2 was < 80 mmHg (10.7 kPa) in six and seven deer with XK and XTZ, respectively, and of these, PaO2 was < 60 mmHg (8.0 kPa) in three and five deer, respectively. With oxygen supplementation, PaO2 increased to 128 ± 4 and 140 ± 5 mmHg (17.1 ± 0.5 and 18.7 ± 0.7 kPa), mean ± standard error, with XK and XTZ, respectively (p < 0.001). PaO2 was not significantly different between treatments at either time point. HR decreased during oxygen supplementation in both treatments (p < 0.001). Lactate was significantly lower (p = 0.047) with XTZ than with XK (2.2 ± 0.6 versus 3.5 ± 0.6 mmol L–1) and decreased (p < 0.001) with oxygen supplementation (4.1 ± 0.6 versus 1.6 ± 0.6 mmol L–1). PaCO2 increased in XTZ during oxygen breathing.Conclusions and clinical relevanceTreatments XK and XTZ resulted in hypoxemia, which responded to oxygen supplementation. Both treatments are suitable for immobilization of white-tailed deer under the study circumstances.  相似文献   

7.
ObjectiveTo determine if pressure support ventilation (PSV) weaning from general anesthesia affects ventilation or oxygenation in horses.Study designProspective randomized clinical study.AnimalsTwenty client‐owned healthy horses aged 5 ± 2 years, weighing 456 ± 90 kg.MethodsIn the control group (CG; n = 10) weaning was performed by a gradual decrease in respiratory rate (fR) and in the PSV group (PSVG; n = 10) by a gradual decrease in fR with PSV. The effect of weaning was considered suboptimal if PaCO2 > 50 mmHg, arterial pH < 7.35 plus PaCO2 > 50 mmHg or PaO2 < 60 mmHg were observed at any time after disconnection from the ventilator until 30 minutes after the horse stood. Threshold values for each index were established and the predictive power of these values was tested.ResultsPressure support ventilation group (PSVG) had (mean ± SD) pH 7.36 ± 0.02 and PaCO2 41 ± 3 mmHg at weaning and the average lowest PaO2 69 ± 6 mmHg was observed 15 minutes post weaning. The CG had pH 7.32 ± 0.02 and PaCO2 57 ± 6 mmHg at weaning and the average lowest PaO2 48 ± 5 mmHg at 15 minutes post weaning. No accuracy in predicting weaning effect was observed for fR (p = 0.3474), minute volume (p = 0.1153), SaO2 (p = 0.1737) and PaO2/PAO2 (p = 0.1529). A high accuracy in predicting an optimal effect of weaning was observed for VT > 10 L (p = 0.0001), fR/VT ratio ≤ 0.60 breaths minute?1 L?1 (p = 0.0001), VT/bodyweight > 18.5 mL kg?1 (p = 0.0001) and PaO2/FiO2 > 298 (p = 0.0002) at weaning. A high accuracy in predicting a suboptimal effect of weaning was observed for VT < 10 L (p = 0.0001), fR/VT ratio ≥ 0.60 breaths minute?1 L?1 (p = 0.0001) and Pe′CO2 ≥ 38 mmHg (p = 0.0001) at weaning.Conclusions and clinical relevancePressure support ventilation (PSV) weaning had a better respiratory outcome. A higher VT, VT/body weight, PaO2/FiO2 ratio and a lower fR/VT ratio and Pe′CO2 were accurate in predicting the effect of weaning in healthy horses recovering from general anesthesia.  相似文献   

8.
ObjectiveTo investigate physiological and sedative/immobilization effects of medetomidine or dexmedetomidine combined with ketamine in free-ranging Chinese water deer (CWD).Study designProspective clinical trial.Animals10 free-ranging adult Chinese water deer (11.0 ± 2.6 kg).MethodsAnimals were darted intramuscularly with 0.08 ± 0.004 mg kg?1 medetomidine and 3.2 ± 0.2 mg kg?1 ketamine (MK) or 0.04 ± 0.01 mg kg?1 dexmedetomidine and 2.9 ± 0.1 mg kg?1 ketamine (DMK) If the animal was still laterally recumbent after 60 minutes of immobilization, atipamezole was administered intravenously (MK: 0.4 ± 0.02 mg kg?1, DMK: 0.2 ± 0.03 mg kg?1). Heart rate (HR) respiratory rate (fR) and temperature were recorded at 5-minute intervals. Arterial blood was taken 15 and 45 minutes after initial injection. Statistical analysis was performed using Student’s t-test or anova. p < 0.05 was considered significant.ResultsAnimals became recumbent rapidly in both groups. Most had involuntary ear twitches, but there was no response to external stimuli. There were no statistical differences in mean HR (MK: 75 ± 14 beats minute?1; DMK: 85 ± 21 beats minute?1), fR (MK: 51 ± 35 breaths minute?1; DMK; 36 ± 9 breaths minute?1), temperature (MK: 38.1 ± 0.7 °C; DMK: 38.4 ± 0.5 °C), blood gas values (MK: PaO2 63 ± 6 mmHg, PaCO2 49.6 ± 2.6 mmHg, HCO3? 30.8 ± 4.5 mmol L?1; DMK: PaO2 77 ± 35 mmHg, PaCO2 45.9 ± 11.5 mmHg, HCO3? 31.0 ± 4.5 mmol L?1) and biochemical values between groups but temperature decreased in both groups. All animals needed antagonism of immobilization after 60 minutes. Recovery was quick and uneventful. There were no adverse effects after recovery.Conclusion and clinical relevanceBoth anaesthetic protocols provided satisfactory immobilisation. There was no clear preference for either protocol and both appear suitable for CWD.  相似文献   

9.
ObjectiveTo evaluate the cardiovascular, respiratory, electrolyte and acid–base effects of a continuous infusion of dexmedetomidine during propofol–isoflurane anesthesia following premedication with dexmedetomidine.Study designProspective experimental study.AnimalsFive adult male Walker Hound dogs 1–2 years of age averaging 25.4 ± 3.6 kg.MethodsDogs were sedated with dexmedetomidine 10 μg kg?1 IM, 78 ± 2.3 minutes (mean ± SD) before general anesthesia. Anesthesia was induced with propofol (2.5 ± 0.5 mg kg?1) IV and maintained with 1.5% isoflurane. Thirty minutes later dexmedetomidine 0.5 μg kg?1 IV was administered over 5 minutes followed by an infusion of 0.5 μg kg?1 hour?1. Cardiac output (CO), heart rate (HR), ECG, direct blood pressure, body temperature, respiratory parameters, acid–base and arterial blood gases and electrolytes were measured 30 and 60 minutes after the infusion started. Data were analyzed via multiple linear regression modeling of individual variables over time, compared to anesthetized baseline values. Data are presented as mean ± SD.ResultsNo statistical difference from baseline for any parameter was measured at any time point. Baseline CO, HR and mean arterial blood pressure (MAP) before infusion were 3.11 ± 0.9 L minute?1, 78 ± 18 beats minute?1 and 96 ± 10 mmHg, respectively. During infusion CO, HR and MAP were 3.20 ± 0.83 L minute?1, 78 ± 14 beats minute?1 and 89 ± 16 mmHg, respectively. No differences were found in respiratory rates, PaO2, PaCO2, pH, base excess, bicarbonate, sodium, potassium, chloride, calcium or lactate measurements before or during infusion.Conclusions and clinical relevanceDexmedetomidine infusion using a loading dose of 0.5 μg kg?1 IV followed by a constant rate infusion of 0.5 μg kg?1 hour?1 does not cause any significant changes beyond those associated with an IM premedication dose of 10 μg kg?1, in propofol–isoflurane anesthetized dogs. IM dexmedetomidine given 108 ± 2 minutes before onset of infusion showed typical significant effects on cardiovascular parameters.  相似文献   

10.
ObjectiveTo determine the cardiopulmonary effects of etorphine and thiafentanil for immobilization of blesbok.Study designBlinded, randomized, two-way crossover study.AnimalsA group of eight adult female blesbok.MethodsAnimals were immobilized twice, once with etorphine (0.09 mg kg–1) and once with thiafentanil (0.09 mg kg–1) administered intramuscularly by dart. Immobilization quality was assessed and analysed by Wilcoxon signed-rank test. Time to final recumbency was compared between treatments by one-way analysis of variance. Cardiopulmonary effects including respiratory rate (?R), arterial blood pressures and arterial blood gases were measured. A linear mixed model was used to assess the effects of drug treatments over the 40 minute immobilization period. Significant differences between treatments, for treatment over time as well as effect of treatment by time on the variables, were analysed (p < 0.05).ResultsThere was no statistical difference (p = 0.186) between treatments for time to recumbency. The mean ?R was lower with etorphine (14 breaths minute–1) than with thiafentanil (19 breaths minute–1, p = 0.034). The overall mean PaCO2 was higher with etorphine [45 mmHg (6.0 kPa)] than with thiafentanil [41 mmHg (5.5 kPa), p = 0.025], whereas PaO2 was lower with etorphine [53 mmHg (7.1 kPa)] than with thiafentanil [64 mmHg (8.5 kPa), p < 0.001]. The systolic arterial pressure measured throughout all time points was higher with thiafentanil than with etorphine (p = 0.04). The difference varied from 30 mmHg at 20 minutes after recumbency to 14 mmHg (standard error difference 2.7 mmHg) at 40 minutes after recumbency. Mean and diastolic arterial pressures were significantly higher with thiafentanil at 20 and 25 minute measurement points only (p < 0.001).ConclusionsBoth drugs caused clinically relevant hypoxaemia; however, it was less severe with thiafentanil. Ventilation was adequate. Hypertension was greater and immobilization scores were lower with thiafentanil.  相似文献   

11.
ObjectiveTo evaluate the efficacy and cardiopulmonary effects of ketamine–midazolam for chemical restraint, isoflurane anesthesia and tramadol or methadone as preventive analgesia in spotted pacas subjected to laparoscopy.Study designProspective placebo-controlled blinded trial.AnimalsA total of eight captive female Cuniculus paca weighing 9.3 ± 0.9 kg.MethodsAnimals were anesthetized on three occasions with 15 day intervals. Manually restrained animals were administered midazolam (0.5 mg kg–1) and ketamine (25 mg kg–1) intramuscularly. Anesthesia was induced and maintained with isoflurane 30 minutes later. Tramadol (5 mg kg–1), methadone (0.5 mg kg–1) or saline (0.05 mL kg–1) were administered intramuscularly 15 minutes prior to laparoscopy. Heart rate (HR), respiratory rate, mean arterial pressure (MAP), peripheral oxygen saturation (SpO2), end-tidal CO2 partial pressure (Pe′CO2), end-tidal concentration of isoflurane (Fe′Iso), pH, PaO2, PaCO2, bicarbonate (HCO3?), anion gap (AG) and base excess (BE) were monitored after chemical restraint, anesthesia induction and at different laparoscopy stages. Postoperative pain was assessed by visual analog scale (VAS) for 24 hours. Variables were compared using anova or Friedman test (p < 0.05).ResultsChemical restraint was effective in 92% of animals. Isoflurane anesthesia was effective; however, HR, MAP, pH and AG decreased, whereas Pe′CO2, PaO2, PaCO2, HCO3? and BE increased. MAP was stable with tramadol and methadone treatments; HR, Fe′Iso and postoperative VAS decreased. VAS was lower for a longer time with methadone treatment; SpO2 and AG decreased, whereas Pe′CO2, PaCO2 and HCO3? increased.Conclusions and clinical relevanceKetamine–midazolam provided satisfactory restraint. Isoflurane anesthesia for laparoscopy was effective but resulted in hypotension and respiratory acidosis. Tramadol and methadone reduced isoflurane requirements, provided postoperative analgesia and caused hypercapnia, with methadone causing severe respiratory depression. Thus, the anesthetic protocol is adequate for laparoscopy in Cuniculus paca; however, methadone should be avoided.  相似文献   

12.
ObjectiveTo investigate the impact of a change in body position on blood gases and arterial blood pressures in foals anesthetized with guaifenesin, ketamine, and xylazine.Study designProspective, randomized experimental study.AnimalsTwelve Quarter Horse foals, age of 5.4 ±0.9 months and weighing 222 ± 48 kg.MethodsFoals were anesthetized with guaifenesin, ketamine, and xylazine for 40 minutes in lateral recumbency and then assigned to a change in lateral recumbency after hoisting (Group 1, n = 6), or no change (Group 2, n = 6). Oxygen 15 L minute?1 was insufflated into the endotracheal tube throughout anesthesia. Arterial blood pressure, heart rate, respiratory rate (fR), inspired fraction of oxygen (FiO2), and end-tidal carbon dioxide (Pe’CO2) were measured every 5 minutes. Arterial pH and blood gases [arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2)] were measured at 10, 30, and 40 minutes after induction, and 5 minutes after hoisting. Alveolar dead space ventilation and PaO2/FiO2 were calculated. Two repeated measures models were used. All hypothesis tests were two-sided and significance level was α = 0.05. All values are presented as least square means ± SE.ResultsValues at time-matched points from the two groups were not significantly different so they were combined. Arterial partial pressure of oxygen decreased significantly from 149 ± 14.4 mmHg before hoisting to 92 ± 11.6 mmHg after hoisting (p=0.0013). The PaO2/FiO2 ratio decreased from 275 ± 30 to 175 ± 24 (p=0.0055). End-tidal carbon dioxide decreased significantly from 48.7 ± 1.6 to 44.5 ± 1.2 mmHg (p=0.021). Arterial partial pressure of carbon dioxide, blood pressures and heart rates measured 5 minutes after hoisting were not different from measurements obtained before hoisting.Conclusion and clinical relevanceHoisting decreased PaO2 in anesthetized healthy foals. Administration of supplemental oxygen is recommended to counter the decrease in oxygenation and PaO2 measurement is necessary to detect early changes.  相似文献   

13.
ObjectiveTo determine the effect of intravenous vatinoxan administration on bradycardia, hypertension and level of anaesthesia induced by medetomidine–tiletamine–zolazepam in red deer (Cervus elaphus).Study design and animalsA total of 10 healthy red deer were included in a randomised, controlled, experimental, crossover study.MethodsDeer were administered a combination of 0.1 mg kg–1 medetomidine hydrochloride and 2.5 mg kg–1 tiletamine–zolazepam intramuscularly, followed by 0.1 mg kg–1 vatinoxan hydrochloride or equivalent volume of saline intravenously (IV) 35 minutes after anaesthetic induction. Heart rate (HR), mean arterial blood pressure (MAP), respiration rate (fR), end-tidal CO2 (Pe′CO2), arterial oxygen saturation (SpO2), rectal temperature (RT) and level of anaesthesia were assessed before saline/vatinoxan administration (baseline) and at intervals for 25 minutes thereafter. Differences within treatments (change from baseline) and between treatments were analysed with linear mixed effect models (p < 0.05).ResultsMaximal (81 ± 10 beats minute–1) HR occurred 90 seconds after vatinoxan injection and remained significantly above baseline (42 ± 4 beats minute–1) for 15 minutes. MAP significantly decreased from baseline (122 ± 10 mmHg) to a minimum MAP of 83 ± 6 mmHg 60 seconds after vatinoxan and remained below baseline until end of anaesthesia. HR remained unchanged from baseline (43 ± 5 beats minute–1) with the saline treatment, whereas MAP decreased significantly (112 ± 16 mmHg) from baseline after 20 minutes. Pe′CO2, fR and SpO2 showed no significant differences between treatments, whereas RT decreased significantly 25 minutes after vatinoxan. Level of anaesthesia was not significantly influenced by vatinoxan.Conclusions and clinical relevanceVatinoxan reversed hypertension and bradycardia induced by medetomidine without causing hypotension or affecting the level of anaesthesia in red deer. However, the effect on HR subsided 15 minutes after vatinoxan IV administration. Vatinoxan has the potential to reduce anaesthetic side effects in non-domestic ruminants immobilised with medetomidine–tiletamine–zolazepam.  相似文献   

14.
ObjectiveTo compare the effect of invasive continuous positive airway pressure (CPAP), pressure-controlled ventilation (PCV) with positive end-expiratory pressure (PEEP) and spontaneous breathing (SB) on PaO2, PaCO2 and arterial to central venous oxygen content difference (CaO2-CcvO2) in healthy anaesthetized dogs.Study designProspective randomized crossover study.AnimalsA group of 15 adult male dogs undergoing elective orchidectomy.MethodsDogs were anaesthetized [buprenorphine, medetomidine, propofol and isoflurane in an air oxygen (FiO2= 0.5)]. All ventilatory treatments (CPAP: 4 cmH2O; PCV: 10 cmH2O driving pressure; PEEP, 4 cmH2O; respiratory rate of 10 breaths minute–1 and inspiratory-to-expiratory ratio of 1:2; SB: no pressure applied) were applied in a randomized order during the same anaesthetic. Arterial and central venous blood samples were collected immediately before the start and at 20 minutes after each treatment. Data were compared using a general linear mixed model (p < 0.05).ResultsMedian PaO2 was significantly higher after PCV [222 mmHg (29.6 kPa)] than after CPAP [202 mmHg (26.9 kPa)] and SB [208 mmHg (27.7 kPa)] (p < 0.001). Median PaCO2 was lower after PCV [48 mmHg (6.4 kPa)] than after CPAP [58 mmHg (7.7 kPa)] and SB [56 mmHg (7.5 kPa)] (p < 0.001). Median CaO2-CcvO2 was greater after PCV (4.36 mL dL–1) than after CPAP (3.41 mL dL–1) and SB (3.23 mL dL–1) (p < 0.001). PaO2, PaCO2 and CaO2-CcvO2 were no different between CPAP and SB (p > 0.99, p = 0.697 and p = 0.922, respectively).Conclusions and clinical relevanceCPAP resulted in similar arterial oxygenation, CO2 elimination and tissue oxygen extraction to SB. PCV resulted in improved arterial oxygenation and CO2 elimination. Greater oxygen extraction occurred with PCV than with CPAP and SB, offsetting its advantage of improved arterial oxygenation. The benefit of invasive CPAP over SB in the healthy anaesthetized dog remains uncertain.  相似文献   

15.
ObjectiveTo test whether partial pressure of CO2 in expired gas (PēCO2) predicts the partial pressure of CO2 in arterial blood (PaCO2) in apneic chickens during air sac insufflation anesthesia at three different ventilation states. Secondary objective: To determine the PēCO2 at which apnea occurs during air sac insufflation anesthesia.Study designRandomized cross-over study.AnimalsTwenty-three healthy male white leghorn chickens.MethodsChickens were anesthetized via mask with isoflurane in oxygen and an air sac cannula was placed in the right abdominal air sac. Delivery of isoflurane in O2 was transferred from the mask to the air sac cannula. The birds were maintained at a surgical plane of anesthesia and apnea was induced by adjusting gas flow; the PēCO2 at apnea was recorded. The birds were then paralyzed and gas flow was adjusted to achieve three different PēCO2s in random order: 43 mmHg (5.6 kPa) [hypoventilation]; 33 mmHg (4.3 kPa) [normoventilation]; and 23 mmHg (3.0 kPa) [hyperventilation]. After maintaining the target expired isoflurane concentration (EIso; 1.85 or 1.90%) and PēCO2 for 15 minutes, arterial blood gas analysis was performed to determine the PaCO2. The chickens were euthanized at the end of the experiment.ResultsBased on Bland-Altman comparisons, PēCO2 was not strongly associated with PaCO2 during the three ventilation states. The PēCO2 at which apnea occurred varied {median (minimum, maximum): 35 (30, 48) mmHg [4.6 (3.9, 6.2) kPa]}.ConclusionsMeasured PēCO2 cannot be used in a simple linear fashion to predict PaCO2 in birds during air sac insufflation anesthesia. The PēCO2 at which apnea occurs during air sac insufflation anesthesia is not predictable.Clinical relevanceArterial blood gases should be used to monitor CO2 during air sac insufflation anesthesia to verify appropriate patient ventilation.  相似文献   

16.
ObjectiveTo compare the cardiopulmonary effects of the opioids etorphine and thiafentanil for immobilization of impala.Study designTwo-way crossover, randomized study.AnimalsA group of eight adult female impala.MethodsImpala were given two treatments: 0.09 mg kg–1 etorphine or 0.09 mg kg–1 thiafentanil via remote dart injection. Time to recumbency, quality of immobilization and recovery were assessed. Respiratory rate, heart rate (HR), mean arterial blood pressure (MAP) and arterial blood gases were measured. A linear mixed model was used to analyse the effects of treatments, treatments over time and interactions of treatment and time (p < 0.05).ResultsTime to recumbency was significantly faster with thiafentanil (2.0 ± 0.8 minutes) than with etorphine (3.9 ± 1.6 minutes; p = 0.007). Both treatments produced bradypnoea, which was more severe at 5 minutes with thiafentanil (7 ± 4 breaths minute–1) than with etorphine (13 ± 12 breaths minute–1; p = 0.004). HR increased with both treatments but significantly decreased over time when etorphine (132 ± 17 to 82 ± 11 beats minute–1) was compared with thiafentanil (113 ± 22 to 107 ± 36 beats minute–1; p < 0.001). Both treatments caused hypertension which was more profound with thiafentanil (mean overall MAP = 140 ± 14 mmHg; p < 0.001). Hypoxaemia occurred with both treatments but was greater with thiafentanil [PaO2 37 ± 13 mmHg (4.9 kPa)] than with etorphine [45 ± 16 mmHg (6.0 kPa)] 5 minutes after recumbency (p < 0.001). After 30 minutes, PaO2 increased to 59 ± 10 mmHg (7.9 kPa) with both treatments (p < 0.001).Conclusions and clinical relevanceThe shorter time to recumbency with thiafentanil may allow easier and faster retrieval in the field. However, thiafentanil caused greater hypertension, and ventilatory effects during the first 10 minutes, after administration.  相似文献   

17.
ObjectiveTo compare the propofol infusion rate and cardiopulmonary effects during total intravenous anesthesia with propofol alone and propofol combined with methadone, fentanyl or nalbuphine in domestic chickens undergoing ulna osteotomy.Study designProspective, randomized, experiment trial.AnimalsA total of 59 healthy Hissex Brown chickens weighing 1.5 ± 0.2 kg.MethodsAnesthesia was induced with propofol (9 mg kg–1) administered intravenously (IV) and maintained with propofol (1.2 mg kg–1 minute–1) for 30 minutes. Birds were intubated and supplemented with 100% oxygen through a nonrebreathing circuit under spontaneous ventilation. Thereafter, each animal was randomly assigned to one of four groups: group P, no treatment; group PM, methadone (6 mg kg–1) intramuscularly (IM); group PN, nalbuphine IM (12.5 mg kg–1); and group PF, fentanyl IV (30 μg kg–1 loading dose, 30 μg kg–1 hour–1 constant rate infusion). During the osteotomy surgery, the propofol infusion rate was adjusted to avoid movement of birds and provide adequate anesthesia. Pulse rate, invasive blood pressure, respiratory frequency, end-tidal carbon dioxide partial pressure (Pe′CO2) and hemoglobin oxygen saturation (SpO2) were recorded.ResultsData were available from 58 chickens. The mean ± standard deviation propofol infusion rate (mg kg–1 minute–1) for the duration of anesthesia was: group P, 0.81 ± 0.15; group PM, 0.66 ± 0.11; group PN, 0.60 ± 0.14; and group PF, 0.80 ± 0.07. Significant differences were P versus PM (p = 0.042), P versus PN (p = 0.002) and PF versus PN (p = 0.004). Pulse rate, blood pressure and SpO2 remained acceptable for anesthetized birds with minor differences among groups. Values of Pe′CO2 >60 mmHg (8 kPa) were observed in all groups.Conclusions and clinical relevanceMethadone and nalbuphine, but not fentanyl, decreased the propofol infusion rate required for anesthesia maintenance, but resulted in no obvious benefit in physiological variables.  相似文献   

18.
ObjectiveTo investigate the cardiorespiratory, nociceptive and endocrine effects of the combination of propofol and remifentanil, in dogs sedated with acepromazine.Study designProspective randomized, blinded, cross-over experimental trial.AnimalsTwelve healthy adult female cross-breed dogs, mean weight 18.4 ± 2.3 kg.MethodsDogs were sedated with intravenous (IV) acepromazine (0.05 mg kg?1) followed by induction of anesthesia with IV propofol (5 mg kg?1). Anesthesia was maintained with IV propofol (0.2 mg kg?1 minute?1) and remifentanil, infused as follows: R1, 0.125 μg kg?1 minute?1; R2, 0.25 μg kg?1 minute?1; and R3, 0.5 μg kg?1 minute?1. The same dogs were administered each dose of remifentanil at 1-week intervals. Heart rate (HR), mean arterial pressure (MAP), respiratory rate (fR), end tidal CO2 (Pe′CO2), arterial hemoglobin O2 saturation, blood gases, and rectal temperature were measured before induction, and 5, 15, 30, 45, 60, 75, 90, and 120 minutes after beginning the infusion. Nociceptive response was investigated by electrical stimulus (50 V, 5 Hz and 10 ms). Blood samples were collected for plasma cortisol measurements. Statistical analysis was performed by anova (p < 0.05).ResultsIn all treatments, HR decreased during anesthesia with increasing doses of remifentanil, and increased significantly immediately after the end of infusion. MAP remained stable during anesthesia (72–98 mmHg). Antinociception was proportional to the remifentanil infusion dose, and was considered satisfactory only with R2 and R3. Plasma cortisol concentration decreased during anesthesia in all treatments. Recovery was smooth and fast in all dogs.Conclusions and clinical relevanceInfusion of 0.25–0.5 μg kg?1 minute?1 remifentanil combined with 0.2 mg kg?1 minute?1 propofol produced little effect on arterial blood pressure and led to a good recovery. The analgesia produced was sufficient to control the nociceptive response applied by electrical stimulation, suggesting that it may be appropriate for performing surgery.  相似文献   

19.
ObjectiveTo describe the pharmacokinetics of ketamine following a short intravenous (IV) infusion to isoflurane-anesthetized rabbits.Study designProspective experimental study.AnimalsA total of six adult healthy female New Zealand White rabbits.MethodsAnesthesia was induced with isoflurane in oxygen. Following determination of isoflurane minimum alveolar concentration (MAC), the isoflurane concentration was reduced to 0.75 MAC and ketamine hydrochloride (5 mg kg–1) was administered IV over 5 minutes. Blood samples were collected before and at 2, 5, 6, 7, 8, 9, 13, 17, 21, 35, 65, 125, 215 and 305 minutes after initiating the ketamine infusion. Samples were processed immediately and the plasma separated and stored at –80 °C until analyzed for ketamine and norketamine concentrations using liquid chromatography–mass spectrometry. Compartment models were fitted to the concentration–time data for ketamine and for ketamine plus norketamine using nonlinear mixed-effects (population) modeling.ResultsA three- and five-compartment model best fitted the plasma concentration–time data for ketamine and for ketamine plus norketamine, respectively. For the ketamine only model, the volume of distribution at steady state (Vss) was 3217 mL kg–1, metabolic clearance was 88 mL minute–1 kg–1 and the terminal half-life was 59 minutes. For the model including both ketamine and norketamine, Vss were 3224 and 2073 mL kg–1, total metabolic clearance was 107 and 52 mL minute–1 kg–1 and terminal half-lives were 52 and 55 minutes for the parent drug and its metabolite, respectively.Conclusions and clinical relevanceThis study characterized the pharmacokinetics of ketamine and norketamine in isoflurane-anesthetized New Zealand White rabbits following short IV infusion. The results obtained herein will be useful to determine ketamine infusion regimens in isoflurane-anesthetized rabbits.  相似文献   

20.
The purpose of this study was to find out if an LMA (#1 LMA‐Classic) would provide a better airway than a face mask in spontaneously breathing anesthetized rabbits, and to test if it could be used for mechanically controlled ventilation. Sixteen rabbits (4.1 ± 0.8 kg, mean ± SD) were assigned randomly to three treatment groups; face mask with spontaneous ventilation (FM‐SV; n = 5), LMA with spontaneous ventilation (LMA‐SV; n = 5), and LMA with controlled ventilation (LMA‐CV; n = 6). Rabbits were anesthetized in dorsal recumbency using a circle circuit at constant ET isoflurane (2.3%, Datex airway gas monitor) and constant rectal temperature (38.85 °C) for 2 hours. PaCO2, PaO2, minute volume, tidal volume (Wright's respirometer), and Pe CO2 were measured at 15 minute intervals. Two individuals in the FM‐SV group had PaCO2 >100 mm Hg (>13.3 kPa). One rabbit in the FM‐SV had PaO2 <80 mm Hg (<10.7 kPa). All FM‐SV rabbits showed signs of airway obstruction and two were withdrawn from the study at 45 and 90 minutes, respectively, because of cyanosis. Tidal volume could not be measured in the FM‐SV group. No signs of airway obstructions were observed in either of the LMA groups. Four rabbits in the LMA‐CV group developed gastric tympany, and one of these refluxed after 110 minutes. The significance of differences between the two spontaneously breathing groups and between the two LMA groups were measured using Wilcoxon's rank sum test (with significance assumed at p < 0.05). There were no statistical differences between FM‐SV and LMA‐SV in any variable tested. PaCO2 and Pe ′CO2 were less in the LMA‐CV group than in the LMA‐SV group, while PaO2, tidal volume, and minute volume were all more. We conclude that biologically, the LMA provides a better airway than the face mask during spontaneous breathing and that it can be used for IPPV, but that gastric tympany is likely to occur during IPPV.  相似文献   

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