Thoracic paravertebral block for an opioid-free thoracotomy in a dog

The Outcomes of an Opioid-Free Anaesthetic Plan in Fourteen Dogs Undergoing Enucleation Using an Ultrasound-Guided Supra-Temporal Retrobulbar Block: A Retrospective Case Series

The objective of this retrospective case series is to report the outcomes of an opioid-free anesthetic plan in dogs undergoing enucleation surgery. A total of 14 dogs were admitted for enucleation between March and December 2020. A multimodal approach to perioperative analgesia was used, with a focus on retrobulbar anesthesia. A combination of an ultrasound-guided retrobulbblock with a supratemporal approach in association with ketamine, dexmedetomidine and non-steroidal anti-inflammatory drugs was used in the reported cases. Intraoperative nociception was defined as an increase of 20% from the baseline in one or more of the following parameters: heart rate, respiratory rate or mean arterial pressure. An ultrasound-guided retrobulbar block in an opioid-free anesthesia regime was effective at managing the perioperative analgesia of 13 out of 14 dogs. In only one case, a bolus of fentanyl was administered to treat intraoperative nociception. Recovery was uneventful in all the dogs, and the postoperative pain scores remained below the intervention threshold at all time points. To the authors' knowledge, this is the first reported case series of opioid-free anesthesia for enucleation in dogs.

A randomized, prospective, masked clinical trial comparing an opioid-free vs. opioid-sparing anesthetic technique in adult cats undergoing ovariohysterectomy

This study aimed to compare the analgesic effects of an injectable protocol using multimodal analgesia with or without opioids in cats undergoing ovariohysterectomy (OVH). Thirty-two healthy cats were enrolled in a prospective, blinded, randomized trial after the caregiver's written consent. Cats received a combination of ketamine (4 mg/kg), midazolam (0.25 mg/kg) and dexmedetomidine (40 μg/kg), and either buprenorphine (20 μg/kg) or saline (same volume as buprenorphine) intramuscularly [opioid-sparing (OSA) and opioid-free anesthesia (OFA) groups, respectively]. Intraperitoneal bupivacaine 0.25% (2 mg/kg) and meloxicam (0.2 mg/kg subcutaneously) were administered before OVH. Atipamezole (400 μg/kg intramuscularly) was administered at the end of surgery. Pain and sedation were evaluated using the Feline Grimace Scale (FGS) and a dynamic interactive visual analog scale, respectively. Intravenous buprenorphine was administered as rescue analgesia if FGS scores ≥ 0.39/1. Statistical analysis included repeated measures linear mixed models, Fisher's exact test and Bonferroni adjustments when appropriate (p < 0.05). Twenty-seven cats were included. The prevalence of rescue analgesia was lower in OSA (n = 0/13) than in OFA (n = 5/14) (p = 0.04). The FGS scores (least square means and 95% CI) were higher in OFA at 1 [2.0 (1.3-2.7)] and 2 h [2.2 (1.5-2.9)] than baseline [0.7 (0.0-1.4)], but not in OSA. Sedation scores were not significantly different between groups. Opioid-free injectable anesthesia was appropriate for some cats using a multimodal approach. However, a single dose of intramuscular buprenorphine eliminated the need for rescue analgesia and assured adequate pain management after OVH in cats.

Effects of Different Doses of Dexmedetomidine Combined with Thoracic Paravertebral Nerve Block Anesthesia on Agitation and Hemodynamics in Patients Undergoing Thoracotomy during Recovery

Objective

To investigate the effect of different doses of dexmedetomidine combined with thoracic paravertebral nerve block anesthesia on agitation and hemodynamics in patients undergoing thoracotomy during recovery.

Methods

One hundred patients who underwent thoracotomy in our hospital from August 2018 to April 2021 were enrolled and assigned (1 : 1 : 1 : 1) into 4 groups via the random number table method. The patients in the control group were treated with double-lumen tube general anesthesia + ropivacaine for thoracic paravertebral nerve block anesthesia; patients in experimental group A received double-lumen general anesthesia +0.5 μg·kg^-1 dexmedetomidine + ropivacaine for thoracic paravertebral nerve block anesthesia; patients in experimental group B received thoracic paravertebral nerve block anesthesia with double-lumen general anesthesia +1.0 μg·kg^-1 dexmedetomidine + ropivacaine; patients in experimental group C received thoracic paravertebral nerve block anesthesia with double-lumen general anesthesia +1.5 μg·kg^-1 dexmedetomidine + ropivacaine. The postoperative recovery time and visual analog scale (VAS), level of hemodynamics (heart rate (HR), mean arterial pressure (MAP)), agitation during the recovery period, and complications were compared amongst the 4 groups of patients at different time points.

Results

The postoperative VAS scores of patients in groups B2 and B3 were slightly lower than those of patients in groups A and B1, but a one-way analysis of variance revealed no statistical difference in the postoperative recovery time and VAS pain scores of the four groups (P > 0.05), and the recovery time of patients in experimental group C was slightly higher than that of patients in group B2. At T0 and T1, there was no significant difference in the levels of HR and MAP among the four groups (P > 0.05). The levels of HR and MAP of the patients in groups B2 and B3 were significantly different from the patients in the control group and experimental group A at T2 and T3 (P < 0.05). The patients in experimental group B and experimental group C showed better outcomes than those in the control group and experimental group A in the assessment of agitation during the recovery period (P < 0.05). There was no significant difference in the incidence of complications among the four groups (P > 0.05).

Conclusion

In line with the principle of preference for a small anesthesia dose, 1.0 μg·kg^-1 dose of dexmedetomidine combined with ropivacaine produces a pronounced efficacy in patients undergoing thoracotomy. It effectively controls the occurrence of agitation during the recovery period and maintains the stability of the patient's hemodynamics, with a high clinical safety profile.