Behavioral and cardiopulmonary effects of dexmedetomidine alone and in combination with butorphanol, methadone, morphine or tramadol in conscious sheep

Objective: To compare cardiopulmonary and sedative effects following administration of dexmedetomidine alone or with butorphanol, methadone, morphine or tramadol in healthy sheep. Study design: Randomized crossover study. Animals: Six Santa Inês sheep, five females, one male, aged 12–28 months and weighing 40.1 ± 6.2 kg. Methods: Sheep were assigned treatments of dexmedetomidine (0.005 mg kg−1; D); D and butorphanol (0.15 mg kg−1; DB); D and methadone (0.5 mg kg−1; DM); D and morphine (0.5 mg kg−1; DMO); or D and tramadol (5.0 mg kg−1; DT). All drugs were administered intravenously with at least 7 days between each treatment. Rectal temperature, heart rate (HR), respiratory rate (fR), invasive arterial pressure, blood gases and electrolytes were measured prior to administration of drugs (baseline, T0) and every 15 minutes following drug administration for 120 minutes (T15–T120). Sedation was scored by three observers blinded to treatment. Results: HR decreased in all treatments and fR decreased in DM at T30 and DMO at T30 and T45. PaCO2 was increased in D, DB and DM compared with baseline, and PaO2 decreased in D at T15 and T45; in DB at T15 to T75; in DM at T15 to T60; in DMO at T15; and in DT at T15, T30 and T75. There was a decrease in temperature in D, DB and DM. An increased pH was measured in D at all time points and in DT at T30–T120. inline image and base excess were increased in all treatments compared with baseline. There were no statistical differences in sedation scores. Conclusions and clinical relevance: The combination of dexmedetomidine with butorphanol, methadone, morphine or tramadol resulted in similar changes in cardiopulmonary function and did not improve sedation when compared with dexmedetomidine alone

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Use of supplemental intravenous anaesthesia / analgesia in horses

General anaesthesia in horses is associated with a significant risk of both morbidity and mortality. One major factor contributing to this is the marked cardiopulmonary depression that occurs in this species in association with the use of volatile anaesthetic agents. Attempts to minimise the required volatile concentration for the maintenance of unconsciousness by administering additional injectable agents may have beneficial effects on the outcome for the animal. This article describes the characteristics of the agents commonly used for supplemental intravenous anaesthesia/analgesia (SIVA), and highlights the key points that must be taken into consideration when undertaking the concurrent administration of these drugs

A comparison of induction of anaesthesia using a target-controlled infusion device in dogs with propofol or a propofol and alfentanil admixture

Objective To compare induction targets, and the haemodynamic and respiratory effects, of propofol, or as an admixture with two different concentrations of alfentanil, delivered via a propofol target-controlled infusion (TCI) system. Study design Prospective blinded randomized clinical study. Animals Sixty client-owned dogs scheduled for elective surgery under general anaesthesia. Mean body mass (SD) 28.5 kg (8.7) and mean age (SD) 3.5 years (2.4). Methods Dogs received pre-anaesthetic medication of acepromazine (0.03 mg kg(-1)) and morphine (0.2 mg kg(-1)) administered intramuscularly. Animals were randomly assigned to receive one of three induction protocols: propofol alone (group 1), a propofol/alfentanil (11.9 mu g mL(-1)) admixture (group 2), or a propofol/alfentanil (23.8 mu g mL(-1)) admixture (group 3), via a TCI system. Blood target concentrations were increased until endotracheal intubation was achieved, and induction targets were recorded. Heart rate (HR), respiratory rate (f(r)) and non-invasive arterial blood pressure were recorded pre-induction, at endotracheal intubation (time 0) and at 3 and 5 minutes post-intubation (times 3 and 5, respectively). Data were analysed using anova for normally distributed data or Kruskal-Wallis test, with significance assumed at p &lt; 0.05. Results There were no significant differences between groups with respect to age, body mass, HR, f(r), systolic and diastolic blood pressure. The blood propofol targets to achieve endotracheal intubation were significantly higher in group 1 compared with groups 2 and 3. Mean arterial blood pressure (MAP) was significantly higher in group 1 at time 0 when compared with groups 2 and 3. Conclusions and clinical relevance Induction of anaesthesia with a TCI system can be achieved at lower blood propofol targets when using a propofol/alfentanil admixture compared with using propofol alone. However, despite reduced targets with both propofol/alfentanil admixture groups, MAP was lower immediately following endotracheal intubation than when using propofol alon

Recovery from anaesthesia in horses 1: what can go wrong?

General anaesthesia of horses carries a significant risk, with the recovery period being a time of particular concern. Over the years, a number of different drugs and techniques have been suggested in order to make the transition from unconsciousness to standing as smooth as possible. However, as yet, there is no single generally accepted method of ensuring that the recovery period will proceed uneventfully. This article, the first of two, will review the factors implicated in potentially poor-quality recovery from anaesthesia in horses, and discuss the complications that may arise, together with how to manage them. The second article, to be published in the next issue of In Practice, will highlight some of the techniques that have been suggested in order to minimise the complications

Recovery from anaesthesia in horses 2: avoiding complications

Complications arising during recovery from anaesthesia in horses are common and, in many cases, potentially fatal. This article, the second of two reviewing this subject, considers how complications might be prevented, with particular emphasis on the different techniques available for assisted recovery. An article published in the July/August issue (In Practice, volume 31, pp 340-347) discussed problems associated with recovery from anaesthesia in horses and how they might be managed appropriately

Evoked otoacoustic emissions: an alternative test of auditory function in horses

&lt;br&gt;Reasons for performing study: Deafness has been reported in horses due to a variety of causes and objective auditory assessment has been performed with brainstem auditory evoked potential testing. Evoked otoacoustic emission (OAE) tests are widely used in human patients for hearing screening, detecting partial hearing loss (including frequency-specific hearing loss) and monitoring cochlear outer hair cell function over time. OAE tests are noninvasive, quick and affordable. Two types of OAE are commonly used clinically: transient evoked OAEs (TEOAEs) and distortion product OAEs (DPOAEs). Detection of OAEs has not been reported and OAE testing has not been evaluated for auditory assessment in horses.&lt;/br&gt; &lt;br&gt;Objectives: To investigate whether TEOAEs and DPOAEs can be recorded in horses, and to evaluate the use of human OAE screening protocols in horses with apparently normal hearing.&lt;/br&gt; &lt;br&gt;Methods: Sixteen systemically healthy horses with normal behavioural responses to sound were included. OAE testing was performed during general anaesthesia using commercially available equipment and the final outcome for each ear for the TEOAE test (after a maximum of 3 runs) and the DPOAE test (after one run) were compared.&lt;/br&gt; &lt;br&gt;Results: TEOAEs and DPOAEs can be recorded in horses. Using the chosen TEOAE protocol, 96% of ears achieved a pass. Seventy percent of ears passed DPOAE testing, despite all of these ears passing TEOAE testing.&lt;/br&gt; &lt;br&gt;Conclusions: Using the chosen stimulus and analysis protocols, TEOAEs were recorded from most ears; however, a smaller proportion of ears passed the DPOAE protocol, suggesting that this may be overly stringent and require further optimisation in horses.&lt;/br&gt; &lt;br&gt;Potential relevance: OAE testing is rapid and easily performed in anaesthetised horses. It provides frequency-specific information about outer hair cell function, and is a promising tool for audiological assessment in the horse; however, it has not been assessed in conscious or sedated animals.&lt;/br&gt