Anaesthetic drug charts

TIVA

TIVA describes maintaining anaesthesia with intravenous agents alone (with or without oxygen). TIVA remains the easiest, cheapest and most efficacious method of providing 'field anaesthesia' or anaesthesia for short procedures. TIVA also has the advantage (compared to inhalational anaesthesia) of causing less cardiopulmonary depression, and therefore better blood pressure throughout the procedure.

Drugs commonly used for TIVA are a combination of:

Alpha-2 agonists. Detomidine 0.01 - 0.04 mg/kg, Romifidine 0.04 - 0.12 mg/kg, Xylazine 0.2 - 2.2 mg/kg.

Muscle relaxants. Commonly Guaifenesin used in a triple drip with Ketamine or Thiopental and an alpha2agonist. For example mixed in 500ml 10% guaifenesin glycopyrrolate OR Diazepam at a single dose of 0.02 – 0.1 mg/kg IV, given in conjunction with the Ketamine.

Dissociative agents. Commonly Ketamine at 2.2mg/kg initial induction dose, then topped with 0.2mg/kg boluses OR Thiopental at 4mg/kg initial induction dose, then topped with 1mg/kg boluses.

Quick reference for commonly used TIVA protocols:

Sedatives

Alpha 2 agonists produce sedation with muscle relaxation, ataxia, and analgesia when given orally, intravenously, or intramuscularly. Commonly used drugs on equine are xylazine, detomidine and romifidine, with preparations which can be administered per OS, IM or IV.

Alpha 2 agonists can produce a number of dose dependant side effects (particularly cardiorespiratory). Common side effects include a decrease in heart rate and increase in peripheral vascular resistance, with a resulting significant decreases in cardiac output. Respiratory rate is usually decreased, but airway impedance along the nasal passages can increase with muscle relaxation, leading to respiratory stridor. Swallowing is impaired and intrauterine and intracranial pressure is increased, as well as causing hyperglycemia, and hypoinsulinemia.

Doses of sedatives:

Detomidine 0.01 - 0.04 mg/kg

Romifidine 0.04 - 0.12 mg/kg

Xylazine 0.2 - 2.2 mg/kg

These are generally associated with an opioid (typically Butorphanol at 0.01 – 0.03 mg/kg, IV) to augment their effect and provide some analgesia.

Analgesics

Analgesia can be provided by systemic or local routes. Local analgesic agents include local aesthetics (see local nerve blocks). Systemic analgesia can be achieved via administration per OS, IM or IV and typically using opioids, NSAIDs and/or steroids.

Common systemic drugs used for analgesia include:

Phenylbutazone 2 - 4 mg/kg OS or IV bid

Flunixin meglumine 1.1 mg/kg IV bid

Meloxicam 0.6 mg/kg OS sid, 0.5 mg/kg IV sid

Dexamethasone 5 mg/kg OS or IV sid

Butorphanol 0.01 – 0.1 mg/kg IV or IM as needed

Morphine 0.1 mg/kg IV or IM sid

Fentanyl 1 – 4 mcg/kg/h