thiopentone - Intensive Care & Coordination Monitoring Unit

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Liverpool Health Service Drug Administration Protocol First Issued: December 2002 Intensive Care Unit Contraindications • Known hypersensitivity to thiopentone and other barbiturates. • Complete absence of suitable veins. • Threatened airway and upper airway obstruction. • Variegate or acute intermittent porphyria. • Constrictive pericarditis, severe cardiovascular disease. • Uncorrected hypovolaemia, hypotension or shock. • Addison's disease, myxoedema, myasthenia gravis. • Hepatic or renal dysfunction, increased blood urea. • Severe anaemia. Precautions • Potassium disturbances – measure levels regularly. • Keep resuscitative and endotracheal intubation equipment and oxygen readily available. • Avoid extravasation or intra-arterial injection. • There is an increased risk of paracetamol toxicity and thus hepatotoxicity (secondary to enzyme induction) when a patient receives paracetamol in conjunction with large doses of thiopentone. Significant Interactions • Probenecid prolongs the action of thiopentone. • Benzodiazepines have a synergistic action when used with thiopentone. • Ethanol increases the CNS depressant effects of thiopentone and ethanol and diazepam increase its hypotensive effects. • Rapid or high doses of ketamine will increase the incidence of hypotension and respiratory depression. • Magnesium sulphate IV increases CNS depressant effects. • Phenothiazines potentiate hypotensive and CNS excitatory effects. • Aminophylline antagonizes thiopentone. • Thiopentone is incompatible in solution with many drugs – flush well and use a dedicated line for infusions. Adverse Effects • Hypotension, tachycardia. • Respiratory depression, apnoea. • Myocardial depression, reduced cardiac output. • Bronchospasm, laryngospasm. • Hypersensitivity reactions – sneezing, pruritus. • Tissue necrosis with extravasation. • Shivering (increased sensitivity to cold) and hypothermia. • Inadequate T lymphocyte function, leading to iatrogenic infections (in large doses, prolonged infusions). • Excitatory phenomena - involuntary muscle movements, coughing, hiccups have been reported. Presentation Thiopentone 500mg ampoule (powder) with 20mL sterile water ampoule for reconstitution. Administration Guidelines • Thiopentone is administered by the intravenous route only. • Individual response to the drug is so varied that there can be no fixed dosage. • Younger patients require relatively larger doses than middle aged and elderly people; the latter metabolise the drug more slowly. • Prepuberty requirements are the same for both sexes, women require less than men. • Dose is usually proportional to bodyweight and for infusions: obese patients require a larger dose than relatively lean people of the same weight. • For induction, the dosage is calculated on the lean body mass. • Discard cloudy solutions or solutions showing a precipitate. • Patients receiving thiopentone for the management of raised intracranial pressure should have continuous EEG monitoring where available. Reviewed: September 2004 Authors: M. Edgtton-Winn Page 2 of 4 Review Date: September 2005
Liverpool Health Service Drug Administration Protocol First Issued: December 2002 Intensive Care Unit Administration Guidelines Induction of anaesthesia: via secure IV line Dilute 500mg thiopentone with 20mL sterile water to arrive at a concentration of 25mg/mL • Bolus 100 – 250mg (4 to 10mL) or 3 – 5mg/kg injected over 10-20 seconds. • Flush the line well, post administration. • Observe blood pressure and need for administration of a volume expander. • Once anaesthesia is established, additional bolus injections of 25 - 50mg (1 to 2mL) can be given according to patient needs. The tone of jaw muscles is a fairly reliable index for achieving anaesthesia. Corneal and conjunctival reflexes disappear. Management of convulsive states: via secure Central Venous access Dilute 2 grams of thiopentone with 50mL sterile water for injection to give a concentration of 40mg/mL. Administer 1 – 3mg/kg and repeat as necessary Infusion Loading Dose: Dilute 2 grams of thiopentone with 50mL sterile water for injection to give a concentration of 40mg/mL. Administer 3mg/kg bolus. Infusion to cease seizure activity: Titrate an infusion of 2 grams thiopentone in 50mL sterile water for injection, to control EEG monitored seizure activity. Management of Raised Intracranial Pressure: via secure Central Venous access Dilute 2 grams of thiopentone with 50mL sterile water for injection to give a concentration of 40mg/mL. 1. Loading Dose: • Administer a loading dose of between 500mg – 2 grams thiopentone over 1 hour 2. Infusion to achieve burst suppression: • Infuse 10mg/kg for up to six hours to achieve burst suppression. • A smaller or greater volume of drug may be required due to individual response and differences in fat deposit uptake of the drug. • When EEG monitoring is utilised, a burst: suppression ratio is prescribed. This is generally 1:1 or 1:2 burst: suppression – indicating absence of brain waves (resting of the cell) with allowance for some electrical breakthrough. • When burst suppression of 1:2 (a 6-second burst of electrical activity followed by a 12-second interval of electrical silence) is achieved, commence a maintenance regime of 3mg/kg/hr. • In the absence of dual channel EEG monitoring, the dose of thiopentone may be reduced in order to avoid over-administration and EEG electrical silence. 3. Infusion for maintenance of required burst suppression ratio: • A maintenance regime is commenced at 3 - 5mg thiopentone/kg/hr. • This may need to be altered to suit the individual patient and achieve the required burst:suppression ratio. • Therapeutic serum level: 6 – 8.5 mg/dL. I f access is by peripheral line, the strength of the solution must be further diluted Reviewed: September 2004 Authors: M. Edgtton-Winn Page 3 of 4 Review Date: September 2005
Page 1: Liverpool Health Service Drug Admin

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