Although success rates and perioperative analgesic requirements were not significantly different, the different exposure to anaesthetic agents suggests that the two techniques may not be equivalent.
Background
To evaluate the effect on arterial blood pressure (ABP) of labetalol infusion as treatment for perioperative non nociceptive acute hypertension in dogs. The clinical records of dogs receiving intra or postoperative labetalol infusion were retrospectively reviewed. Invasive systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressure and heart rate (HR) before labetalol infusion (T0) and 15, 30, 45 and 60 min (T1, T2, T3 and T4 respectively) after infusion were retrieved. The dose rate of labetalol infusion and use of concurrently administered drugs that could have potentially affected ABP and/or HR were also recorded. ANOVA for repeated measures and Dunnett’s multiple comparison test were used to determine the effect of labetalol on ABP and HR. Differences were considered significant when
p
< 0.05.
Results
A total of 20 dogs met the inclusion criteria, and hypertension was documented after craniotomy (12/20), adrenalectomy (4/20) and other procedures (4/20). Five dogs received labetalol intraoperatively, 14 postoperatively, and 1 during the surgical procedure and recovery. Median infusion duration and rate were 463 (60-2120) minutes and 1.1 (0.2–3.4) mg/kg/h respectively. Median loading dose was 0.2 (0.2–0.4) mg/kg. Labetalol produced a significant decrease in SAP and DAP at all time points compared to T0 (
p
< 0.05), while the effect was not significant at T1 for MAP (
p
= 0.0519). Median maximum MAP decrease was 31 (20–90) mmHg. Heart rate did not increase significantly during treatment (
p
= 0.2454). Acepromazine given before or during labetalol treatment did not reduce significantly ABP (
p
= 0.735).
Conclusions
Labetalol produced a reliable and titratable decrease in ABP with non significant increase in HR.
Hypobaric spinal anaesthesia achieved unilateral postoperative pelvic limb motor blockade in dogs, although bilateral block occurred in a proportion of animals; intraoperative hypotension was not infrequent. Fentanyl and postoperative methadone might be required to control nociception and pain, despite technical success in performing spinal anaesthesia.
A 3‐month‐old female Cocker Spaniel was presented for investigation of a V/VI left basilar heart murmur and diagnosed with a double‐chambered right ventricle. Atenolol was prescribed for 3 months before surgical correction of the congenital anomaly, combining cutting balloon and high‐pressure balloon (CB‐HPB) dilation. A few days before the intervention, the dog showed signs of right‐sided congestive heart failure and it was treated with furosemide, benazepril/spironolactone and pleural effusion were drained. During CB‐HPB dilation, cardiac index and systemic arterial blood pressure suddenly decreased on two occasions probably secondary to a dynamic right ventricular outflow tract obstruction. Cardiac arrest occurred and cardiopulmonary resuscitation was unsuccessful.
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