Cardiorespiratory and anaesthetic effects of two continuous rate infusions of dexmedetomidine in alfaxalone anaesthetized dogs.

Six Beagles were used in this prospective randomised crossover experimental study. Dexmedetomidine was administered at 0, 1 or 2 µg/kg IV for group C, LDA and HDA, respectively. Animals were induced and maintained with alfaxalone at 0.07 mg/kg/min with a CRI dexmedetomidine dose of 0, 0.5 or 1 µg/kg/h for group C, LDA and HDA, respectively. Cardiorespiratory variables, arterial blood gases and depth of anaesthesia were recorded. The recovery times and quality of recovery were scored. Group HDA produced a greater increase in the depth of anaesthesia than LDA. However, with both protocols, CI was halved compared to normal values in dogs. The use of oxygen before and during the anaesthetic maintenance is advisable, mainly if dexmedetomidine is going to be use as a pre-medicant and maintenance agent. The quality of recovery was better in groups receiving dexmedetomidine, without causing an increase in recovery time.

Pharmacokinetics of the individual enantiomer S-(+)-ketoprofen after intravenous and oral administration in dogs at two dose levels.

The pharmacokinetic of the individual S-(+)-enantiomer of ketoprofen, S-(+)-ketoprofen, after intravenous (IV) and oral (PO) administration was determined in six dogs at 1 and 3 mg/kg. Plasma concentrations were determined by high performance liquid chromatography with ultraviolet detection. The concentration-time curves were analyzed by non-compartmental methods. Steady-state volume of distribution (Vss) and clearance (Cl) of S-(+)-ketoprofen after IV administration were 0.22 ± 0.07 and 0.19 ± 0.03 L/kg, and 0.10 ± 0.02 and 0.09 ± 0.01 L/h/kg, at 1 and 3 mg/kg, respectively. Following PO administration, S-(+)-ketoprofen achieved maximum plasma concentrations of 4.91 ± 0.76 and 12.47 ± 0.62 µg/ml, at two dose levels, respectively. The absolute bioavailability after PO route was 88.66 ± 12.95% and 85.36 ± 13.90%, respectively.

Cardiorespiratory, anaesthetic and recovery effects of morphine combined with medetomidine and alfaxalone in rabbits.

Ten New Zealand White rabbits were used in a crossover experimental study: 200 µg/kg medetomidine and 1 (M1) or 2 mg/kg (M2) morphine were administered intramuscularly. After preoxygenation, anaesthesia was induced with alfaxalone at 10 mg/kg intravenously. The trachea was intubated and 60 per cent oxygen provided. Heart and respiratory rates (HR and RR), direct arterial pressures (APs), arterial pH (pHa), PaO2, PaCO2 and SaO2 were taken at baseline, after premedication and every 10 minutes during the 90 minutes following induction. The times to return the ear pinch, toe pinch and righting reflexes were recorded. Data were analysed using a two-way analysis of variance and a paired samples t test. Compared to baseline values, HR, RR, APs, PaO2 and SaO2 decreased significantly after premedication in both groups. Postinduction apnoea of 20 ± 10 with M1 and 27 ± 18 minutes with M2 was experienced following alfaxalone administration, intermitent positive pressure ventilation was applied until spontaneous breathing efforts appeared. Cardiovascular variables, RR and pHa remained below, and PaCO2 over baseline values during the anaesthetic period. No significant differences were observed in the recovery times. Morphine at 1 or 2 mg/kg combined with medetomidine and alfaxalone in rabbits produced a suitable level of anaesthesia, although profound cardiorespiratory depression was found.

Postoperative analgesic effects of dexketoprofen, buprenorphine and tramadol in dogs undergoing ovariohysterectomy.

The objective of this study was to compare the postoperative analgesic effects of dexketoprofen, tramadol, and buprenorphine in dogs undergoing ovariohysterectomy. Seventy-five adult female dogs were randomly assigned to receive an intravenous injection (IV) of 1mg/kg of dexketoprofen (D), 0.02 mg/kg of buprenorphine (B) or 2mg/kg of tramadol (T). Pain assessment was performed during 48 h after ovariohysterectomy using a dynamic interactive visual analogue scale (DIVAS) and Glasgow composite measure pain scale (CMPS-SF). Rescue analgesia was required in 43%, 21%, and 5% of dogs in the B, T, and D groups, respectively, with significant differences between B and D (p=0.010) groups. The DIVAS and CMPS-SF values of the B group were significantly higher than those of the T and D groups. The most common undesirable effect was dysphoria in dexketoprofen group. Tramadol and dexketoprofen provide superior postoperative analgesia compared with buprenorphine in dogs undergoing ovariohysterectomy.

Retrospective study of the prevalence of postanaesthetic hypothermia in dogs.

The anaesthetic records of 1525 dogs were examined to determine the prevalence of postanaesthetic hypothermia, its clinical predictors and consequences. Temperature was recorded throughout the anaesthesia. At the end of the procedure, details coded in were: hyperthermia (>39.50°C), normothermia (38.50°C-39.50°C), slight (38.49°C-36.50°C), moderate (36.49°C-34.00°C) and severe hypothermia (<34.00°C). Statistical analysis consisted of multiple regression to identify the factors that are associated with the temperature at the end of the procedure. Before premedication, the temperature was 38.7 ± 0.6°C (mean ± sd). At 60, 120 and 180 minutes from induction, the temperature was 36.7 ± 1.3°C, 36.1 ± 1.4°C and 35.8 ± 1.5°C, respectively. The prevalence of hypothermia was: slight, 51.5 per cent (95 per cent CI 49.0 to 54.0 per cent); moderate, 29.3 per cent (27.1-31.7 per cent) and severe: 2.8% (2.0-3.7%). The variables that associated with a decrease in the temperature recorded at the end of the anaesthesia were: duration of the preanesthetic time, duration of the anaesthesia, physical condition (ASA III and ASA IV dogs showed lower temperatures than ASA I dogs), the reason for anaesthesia (anaesthesia for diagnostic procedures or thoracic surgery reduce the temperature when compared with minor procedures), and the recumbency during the procedure (sternal and dorsal recumbencies showed lower temperatures than lateral recumbency). The temperature before premedication and the body surface (BS) were associated with a higher temperature at the end of the anaesthesia, and would be considered as protective factors.

Anaesthetic and cardiorespiratory effects of a constant-rate infusion of alfaxalone in desflurane-anaesthetised sheep.

A prospective, randomised, blinded controlled study was performed to determine the anaesthetic and cardiorespiratory effects of a constant-rate infusion (CRI) of alfaxalone in 12 sheep anaesthetised with desflurane, and undergoing experimental orthopaedic surgery. Sheep were sedated with dexmedetomidine (4 µg/kg, intravenously) and butorphanol (0.3 mg/kg, intravenously). Anaesthesia was induced with alfaxalone (1 mg/kg/minute to effect, intravenously) and maintained with desflurane in oxygen and alfaxalone 0.07 mg/kg/minute or saline for 150 minutes (range 150-166 minutes). The anaesthetic induction dose of alfaxalone, the desflurane expiratory fraction required for anaesthetic maintenance, cardiorespiratory measurements and blood-gases were recorded at predetermined intervals. Quality of sedation, anaesthetic induction and recovery were assessed. The alfaxalone induction dose was 1.7 mg/kg (1.2 to 2.6 mg/kg). The desflurane expiratory fraction was lower (22 per cent) in sheep receiving alfaxalone CRI (P=0). Also, heart rate (P=0), cardiac index (P=0.002), stroke index (P=0) and contractility (P=0) were higher, and systemic vascular resistance (P=0.002) was lower. Although respiratory rate tended to be higher with alfaxalone, there was no difference in PCO2 between the groups. Recovery times were significantly longer in sheep given alfaxalone (25.4 v 9.5 minutes) but recovery quality was similar. Alfaxalone reduced requirements of desflurane and maintained similar cardiorespiratory function, but recovery time was more prolonged.

[Development of a septic shock experimental model oriented at training. Application in the training of depuration techniques in the management of severe sepsis]. / Desarrollo de un modelo experimental de shock séptico orientado a la formación. Aplicación en el entrenamiento de técnicas de depuración en el manejo de la sepsis grave.

OBJECTIVE: To define a septic shock experimental model that can be used in for training in the early management of septic shock, specifically by extracorporeal depuration (ECD). DESIGN: A case-control experimental study. SETTING: Veterinary university hospital. SUBJECTS: Ten Beagle dogs (weight 12-15kg). INTERVENTIONS: Shock was induced using 1mg/kg Escherichia coli lipopolysaccharide (LPS) diluted in 20 mL saline infused in 10 minutes, with a subsequent follow-up at 6 hours. There was no intervention in 5 animals in order to define the natural course of the shock and 5 underwent high volume hemofiltration (HVHF, 100mL/kg/h) to define delay in response to treatment. VARIABLES: Pressures (arterial and pulmonary), hemodynamic parameters, gastric tonometry and respiratory function were recorded. RESULTS: The LPS effect was evidenced at 2 minutes of the infusion and the 10 animals showed severe shock at the end of the infusion. At 2-hours, changes between treated and non-treated animals were seen in cardiac output, systolic volume variability and mucous CO(2). Mean arterial pressure was significantly different at four hours. All non-treated subjects died during the 6-hour follow-up and all the treated animals survived for this period. Based on these results, we developed a workshop that has been used in five courses (www.ccmijesususon.com - www.crrtcordoba.com.es/), obtaining the previous results. CONCLUSIONS: Our shock model shows a predictable behavior, very short latency and a sufficiently rapid improvement in the treated animals for it to be applied in training workshops. It is useful for training in the high-volume hemofiltration (HVHF) and can be used for training in the early management of septic shock.

Relationship of bispectral index to hemodynamic variables and alveolar concentration multiples of sevoflurane in puppies.

The relationships between bispectral index (BIS), cardiovascular variables and minimum alveolar concentration (MAC) multiples of sevoflurane in puppies were determined. Five puppies were anesthetized with sevoflurane on two occasions. First, the individual sevoflurane MAC values were determined for each puppy. Secondly, dogs were anesthetized with sevoflurane at each of 5 MAC multiples, 0.75, 1, 1.25, 1.5 and 1.75 MAC administered in random order. Hemodynamic parameters and BIS data were collected for 20min. Somatic stimulus was then applied and the same parameters and data were collected for 6min. Correlation between BIS and end tidal sevoflurane and between BIS and hemodynamic parameters were studied. We found positive significant correlation in both cases. BIS is lower in puppies that in adults at the same alveolar anesthetic concentrations and sevoflurane appears to be a safe anesthetic in puppies.

Effect of medetomidine infusion on the anaesthetic requirements of desflurane in dogs.

The objective of this paper was to evaluate the effect of constant rate infusion of medetomidine on the anaesthetic requirements of desflurane in dogs. For this, six healthy dogs were studied. Measurements for baseline were taken in the awake, unsedated dogs, then each dog received intravenously (i.v.) three anaesthetic protocols: M (no medetomidine infusion), M0.5 (infusion of medetomidine at 0.5 microg/kg/h, i.v.) or M1 (infusion of medetomidine at 1 microg/kg/h, i.v.). All dogs were sedated with medetomidine (2 microg/kg, i.v.) and measurements repeated in 10 min. Induction of anaesthesia was delivered with propofol (3 mg/kg, i.v.) and maintained with desflurane for 90 min to achieve a defined surgical plane of anaesthesia in all cases. After tracheal intubation infusion of medetomidine was initiated and maintained until the end of anaesthesia. Cardiovascular, respiratory, arterial pH (pHa) and arterial blood gas tensions (PaO(2), PaCO(2)) variables were measured during the procedure. End tidal desflurane concentration (EtDES) was recorded throughout anaesthesia. Time to extubation, time to sternal recumbency and time to standing were also noted. Heart rate and respiratory rate were significantly decreased during sedation in all protocols compared to baseline values. Mean heart rate, mean arterial pressure, systolic arterial pressure, diastolic arterial pressure, respiratory rate, tidal volume, arterial oxygen saturation, end-tidal CO(2), pHa, PaO(2), and PaCO(2) during anaesthesia were similar for all protocols. EtDES for M (8.6 +/- 0.8%) was statistically higher than for M0.5 (7.6 +/- 0.5%) and M1 (7.3 +/- 0.7%) protocols. Infusion of medetomidine reduces desflurane concentration required to maintain anaesthesia in dogs.

Normal values and incidence of cardiorespiratory complications in dogs during general anaesthesia. A review of 1281 cases.

This paper describes the cardiorespiratory variables and the incidence of anaesthetic complications in dogs. For this, a retrospective study of 1281 anaesthesias was performed. Heart rate (HR), non-invasive mean arterial (MAP), systolic (SP) and diastolic pressures (DP), invasive mean arterial (IMAP), systolic (ISP) and diastolic pressures (IDP), central venous pressure (CVP), respiratory rate (RR), tidal volume (V(T)), minute volume (V(M)), end-tidal CO(2) (EtCO(2)), arterial oxygen saturation (SpO(2)), temperature (T) and death are reported. Data were described both globally and separately for each ASA (American Society of Anaesthesiologists classification) status. An ANOVA and a Tukey's test were used for comparing the different ASA status' values (alpha=0.05). During anaesthetic maintenance, the mean +/- SD of the studied variables were: HR: 91+/-27 bpm. MAP: 86+/-24 mmHg. IMAP: 80+/-22 mmHg. SP: 114+/-25 mmHg. ISP: 109+/-26 mmHg. DP: 67+/-23 mmHg. IDP: 66+/-22 mmHg. CVP: 5+/-3 mmHg. RR: 19+/-11 rpm. V(T): 14+/-7 ml/kg. V(M): 191+/-93 ml/kg/min. EtCO(2): 40+/-8 mmHg. T: 37.1+/-1.7 degrees C. ASA III and ASA IV patients, compared with those with ASA I, showed higher values of HR, RR, V(T) and V(M) and lower in IMAP, CVP, EtCO(2), SpO(2) and T. The most frequent complications were bradycardia (36.3% of the patients), hypotension (37.9%), hypoventilation (63.4%), hypoxia (16.4%), hypothermia (4.8%) and death (0.9%). Cardiorespiratory complications frequently occur in dogs during general anaesthesia.

Comparison of romifidine and medetomidine pre-medication in propofol-isoflurane anaesthetised dogs.

The objective of this paper was to evaluate romifidine as a pre-medicant in dogs prior to propofol-isoflurane anaesthesia, and to compare it with medetomidine. For this, eight healthy dogs were anaesthetised. Each dog received three pre-anaesthetic protocols: R40 (romifidine, 40 microg/kg, IV), R80 (romifidine, 80 microg/kg, IV) or MED (medetomidine, 10 microg/kg, IV). Induction of anaesthesia was delivered with propofol and maintained with isoflurane. The following variables were studied before sedative administration and 10 min after sedative administration: heart rate (HR), mean arterial pressure (MAP), systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) and respiratory rate (RR). During maintenance, the following variables were recorded at 5-min intervals: HR, MAP, SAD, DAP, arterial oxygen saturation (SpO(2)), end-tidal CO(2)(EtCO(2)), end-tidal concentration of isoflurane (EtISO) required for maintenance of anaesthesia and tidal volume (TV). Time to extubation, time to sternal recumbency and time to standing were also registered. HR and RR experimented a significantly decreased during sedation in all protocols respect to baseline values. Mean HR, MAP, SAP, DAP, SpO(2), EtCO(2), and TV during anaesthesia were similar for the three protocols. End tidal of isoflurane concentration was statistically similar for all protocols. Recovery time for R40 was significantly shorter than in R80 and MED. The studied combination of romifidine, propofol and isoflurane appears to be an effective drug combination for inducing and maintaining general anaesthesia in healthy dogs.

Dexmedetomidine or medetomidine premedication before propofol-desflurane anaesthesia in dogs.

The objective of this study was to evaluate dexmedetomidine as a premedicant in dogs prior to propofol-desflurane anaesthesia, and to compare it with medetomidine. Six healthy dogs were anaesthetized. Each dog received intravenously (i.v.) five preanaesthetic protocols: D1 (dexmedetomidine, 1 microg/kg, i.v.), D2 (dexmedetomidine, 2 microg/kg, i.v.), M1 (medetomidine, 1 microg/kg, i.v.), M2 (medetomidine, 2 microg/kg, i.v.), or M4 (medetomidine, 4 microg/kg, i.v.). Anaesthesia was induced with propofol (2.3-3.3 mg/kg) and maintained with desflurane. The following variables were studied: heart rate (HR), mean arterial pressure, systolic arterial pressure, diastolic arterial pressure, respiratory rate (RR), arterial oxygen saturation, end-tidal CO2, end-tidal concentration of desflurane (EtDES) required for maintenance of anaesthesia and tidal volume. Arterial blood pH (pHa) and arterial blood gas tensions (PaO2, PaCO2) were measured during anaesthesia. Time to extubation, time to sternal recumbency and time to standing were also recorded. HR and RR decreased significantly during sedation in all protocols. Cardiorespiratory variables during anaesthesia were statistically similar for all protocols. EtDES was significantly different between D1 (8.1%) and D2 (7.5%), and between all doses of medetomidine. Desflurane requirements were similar for D1 and M2, and for D2 and M4 protocols. No statistical differences were observed in recovery times. The combination of dexmedetomidine, propofol and desflurane appears to be effective for induction and maintenance of general anaesthesia in healthy dogs.

Fluorangiographic alterations in a dog with suspected iatrogenic partial carotid artery occlusion.

During routine fluorescein angiography, a healthy female dog demonstrated abnormal delayed filling of retinal and choroidal vessels. Fluorangiographic times were increased four- to fivefold with respect to reference values. Fluorescein angiography, using the same protocol, was repeated two weeks later and a fluorangiogram within reference values was obtained. The abnormal results in the first procedure were suspected to have resulted from partial occlusion of the carotid artery secondary to the restraining method used.

Effects of sevoflurane, isoflurane and halotane anaesthesia on fluorescein angiographic phases of dogs: a comparative study.

A fluorescein angiography method was developed to compare the onset and the total duration of the fluorangiographic phases between three anaesthetic protocols in six healthy mixed-breed dogs. The animals were anaesthetized three times. Each dog received, as pre-anaesthetic protocol, atropine (10 micrograms/kg intramuscularly), and as a sedative, romifidine (80 micrograms/kg intravenously). Fifteen minutes later, induction of anaesthesia was delivered with propofol (1 mg/kg intravenously) and maintained either with sevoflurane (SEVO group), isoflurane (ISO group) or halothane (HAL group) for 30 min in all cases. Some angiographic, cardiovascular and respiratory variables were registered during the procedure. Recovery times were also registered. Angiographic variables recorded were: onset of the arterial phase (TA), onset of the arteriovenous phase (TAV), onset of the venous phase (TV), complete arterial phase duration (I1), complete arteriovenous phase duration (I2) and I1 plus I2 (I3). Mean heart rate, mean arterial pressure, systolic arterial pressure, diastolic arterial pressure, respiratory rate, tidal volume, arterial oxygen saturation and end-tidal CO2 during SEVO and ISO anaesthesia, were similar in dogs. Minute ventilation and rectal temperature were higher in dogs with SEVO than ISO. HAL produced higher arterial pressures and a lower arterial oxygen saturation than ISO and SEVO. Mean respiratory rate, rectal temperature and minute ventilation were higher in HAL. Pulse rate, end-tidal CO2 and tidal volume were similar in the dogs of the three groups. No differences in recovery times were found. The fluorescein angiographic times were within the normal range. There were no significant differences between protocols in I1, I2 or I3. HAL produced a significant increase of all temporal variables (TA, TAV and TV) when compared with ISO; TA was higher in HAL than SEVO-treated dogs. All protocols appear to be safe and effective for inducing and maintaining general anaesthesia in healthy dogs for performing fluorescein angiography.

Propofol or thiopentone as induction agents in romifidine-sedated and halothane-N2O-anesthetized dogs: a preliminary study.

The objective of this paper was to evaluate the use of romifidine as a premedicant in dogs before general anesthesia induced with propofol or thiopentone and maintained with halothane-N2O. Fifteen healthy dogs were anesthetized twice. Each dog received, as preanesthetic protocol, atropine (10 microg/kg, IM) and romifidine (40 microg/kg, IM); induction was delivered with propofol or thiopentone and anesthesia was maintained with halothane and N2O for 1 h. Some cardiovascular and respiratory variables and recovery times were recorded. Induction doses of propofol or thiopentone and the percentage of halothane necessary for maintaining anesthesia were also registered. Thiopentone as an induction agent is more respiratory depressive but is less hypotensive than propofol. Thiopentone reduces further the percentage of halothane necessary for maintaining the anesthesia. However, the quality of recovery is poorer, as the time to extubation is longer and the dogs occasionally had a violent recovery. The combination of romifidine, atropine, propofol, halothane, and N2O appears to be an effective combination for inducing and maintaining general anesthesia in healthy dogs.

Alpha-2 agonist dissociative anesthetic combinations in fallow deer (Cervus dama).

Three anesthetic protocols, each using an alpha-2 agonist sedative in combination with a dissociative anesthetic, were evaluated in 17 captive fallow deer (Cervus dama). The alpha-2 agonist was given first in two of the three protocols: 1) detomidine (0.1-0.2 mg/kg i.m.) followed by tiletamine-zolazepam (3.0-6.3 mg/kg i.m.) and 2) xylazine (0.6-0.9 mg/kg i.m.) followed by tiletamine-zolazepam (4-5 mg/kg i.m.). In the third protocol, xylazine (1.0-6.2 mg/kg i.m.) and ketamine (2.5-5.1 mg/kg i.m.) were given simultaneously. Each of the sedative/anesthetic combinations produced acceptable immobilization in fallow deer and both provide an alternative to narcotic anesthesia.

Romifidine, medetomidine or xylazine before propofol-halothane-N2O anesthesia in dogs.

The objective of this paper was to evaluate romifidine as a premedicant in dogs prior to propofol-halothane-N2O anesthesia, and to compare it with the other alpha2-agonists (medetomidine and xylazine). For this, ten healthy dogs were anesthetized. Each dog received 3 preanesthetic protocols: atropine (10 microg/kg BW, IM), and as a sedative, romifidine (ROM; 40 microg/kg BW, IM), xylazine (XYL; 1 microg/kg, IM), or medetomidine (MED; 20 microg/kg BW, IM). Induction of anesthesia was delivered with propofol 15 min later and maintained with halothane and N2O for one hour in all cases. The following variables were registered before preanesthesia, 10 min after the administration of preanesthesia, and at 5-minute intervals during maintenance: PR, RR, rectal temperature (RT), MAP, SAP, and DAP. During maintenance, arterial oxygen saturation (SpO2), end-tidal CO2 (EtCO2) and percentage of halothane necessary for maintaining anesthesia (%HAL) were also recorded. Induction dose of propofol (DOSE), time to extubation (TE), time to sternal recumbency (TSR) and time to standing (TS) were also registered. The statistical analysis was carried out during the anesthetic period. ANOVA for repeat measures revealed no differences between the 3 groups for PR and RR; however, MAP, SAP and DAP were higher in the MED group; SpO2 was lower in MED and EtCO2 was lower in ROM; %HAL was higher in XYL. No statistical differences were observed in DOSE, TE, TSR or TS. Percentage of halothane was lower in romifidine and medetomidine than in xylazine premedicated dogs also anesthetized with propofol. All the cardiorespiratory variables measured were within normal limits. The studied combination of romifidine, atropine, propofol, halothane and N2O appears to be a safe and effective drug combination for inducing and maintaining general anesthesia in healthy dogs.