The effect of aquapuncture at Pericardium 6 (PC-6) on dexmedetomidine-induced nausea and vomiting in cats

Abstract

Objective

To determine the effect of aquapuncture at acupuncture point Pericardium 6 (PC-6) on the incidence of dexmedetomidine-induced vomiting and nausea in cats.

Study design

Randomized, prospective, crossover study.

Animals

A group of 22 cats, 14 females and eight males, aged 1–12 years and weighing 3.8–5.9 kg.

Methods

Each cat was administered treatments in random order at ≥1 week intervals. For treatment (DEX–A), cats were administered PC-6 stimulation by aquapuncture (0.25 mL/250 μg vitamin B12 injection subcutaneously at PC-6). After 30 minutes, dexmedetomidine (10 μg kg^–1) was administered intramuscularly (IM). For control treatment (DEX), cats were administered only dexmedetomidine (10 μg kg^–1) IM. Incidence of vomiting, number of vomiting episodes and time to first vomiting were recorded by an observer unaware of treatment allocation. At 30 minutes after dexmedetomidine administration, atipamezole (0.1 mg kg^–1) was injected IM. Behavior was video recorded and later scored by two observers for clinical signs of nausea. A regression model (analysis of covariance) was used to detect the influence of aquapuncture on vomiting and nausea. Significance was set at p < 0.05.

Results

Of 21 cats, 18 (85%) and 16 cats (76%) vomited in DEX–A and DEX, respectively. There was no significant difference in the incidence of vomiting (p = 0.55), number of vomiting episodes (p = 0.55), mean time to vomit (p = 0.88) or nausea score (p = 0.51) between DEX–A and DEX.

Conclusions and clinical relevance

PC-6 aquapuncture did not reduce the incidence of dexmedetomidine-induced vomiting or severity of nausea in cats.

Introduction

Perianesthetic drug-induced nausea and vomiting can lead to anesthetic complications such as aspiration pneumonia and increased intraocular and intracranial pressure. Furthermore, humans report postoperative nausea and vomiting (PONV) to be a highly distressing part of their surgical experience (Kerger et al. 2007).

Acupuncture at point Pericardium-6 (PC-6) significantly reduces vomiting and nausea in humans and dogs following anesthesia and opioid administration (Lee et al., 2015, Scallan and Simon, 2016). In humans, PC-6 stimulation has shown similar efficacy to ondansetron, a 5HT₃ antagonist, at preventing PONV (Ravi et al. 2010). To date, there is no published study on the use of this acupuncture point in cats.

Dexmedetomidine is an α₂-adrenergic receptor agonist routinely used in veterinary medicine to provide analgesia and sedation (Mendes et al. 2003). When administered as a single agent to cats, either intramuscularly (IM) or intravenously (IV), dexmedetomidine causes vomiting with an incidence rate as high as 81% (Thawley & Drobatz 2015).

Acupuncture points can be stimulated in a variety of ways beyond traditional needle placement, such as acupressure. Aquapuncture, a type of acupressure, is the subcutaneous injection of slowly resorbed fluid at the acupuncture point. Liquid vitamin B12 is often used for this purpose (Altman 2001). The pressure applied by the subcutaneous fluid stimulates the acupuncture point and is useful in animals that do not tolerate prolonged acupuncture needle placement. Because cats are less likely to tolerate prolonged needle placement, aquapuncture was utilized for point stimulation in this study.

The purpose of this study was to evaluate the effects of stimulation of PC-6 on the incidence of dexmedetomidine-induced vomiting and nausea in cats. We hypothesized that aquapuncture at PC-6 30 minutes prior to the administration of dexmedetomidine (10 μg kg^–1) IM would reduce the incidence of vomiting and severity of nausea in cats.