Sedation Strategies For Standing Surgery
Páginas: 5 (1093 palabras)
Publicado: 29 de agosto de 2011
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Proceedings of the 47th British Equine Veterinary Association Congress BEVA
Sep. 10 – 13, 2008 Liverpool, United Kingdom
Next Congress:
Reprinted in IVIS with the permission of the British Equine Veterinary Association – BEVA http://www.ivis.org/
Reprinted in IVIS with the permission of BEVA
Close this window to return to IVISFriday
Hall 1A
16.50–17.10
Sedation strategies for standing surgery
Andrew Harrison
Three Counties Equine Hospital, Stratford Bridge, Ripple, Tewkesbury, Gloucestershire GL20 6HE, UK.
The primary objective is to enable surgery to be performed in the standing horse, by minimising or preferably abolishing movement of the patient in response to both noxious (surgical) and non-noxious(e.g. noise) stimuli. This is achieved by calming the patient usually chemically, and providing adequate analgesia and anaesthesia. Physical restraint is aided by the use of stocks where appropriate. However, it is important to ensure that airway patency is maintained. Blindfolding and the use of cotton wool earplugs may assist in reducing visual and auditory responses (remember to remove theearplugs on completion of the procedure!). Chemical restraint is usually achieved with a combination of pharmacological agents, either as a bolus or as a continuous infusion, in conjunction with any appropriate local anaesthetic techniques. DRUGS AND DRUG COMBINATIONS Phenothiazines Acepromazine maleate, is the most commonly used phenothiazine in equine practice. It produces a mental calming effect inmost animals. Although the degree of sedation is only mild and it provides no analgesia, it is an important part of the anaesthetic protocol. Dose: 0.04 mg/kg bwt i.v. or i.m. Alpha-2 agonists Alpha-2 agonists have a dual action in providing reliable, dose-dependent sedation and good analgesia in most horses. These drugs (xylazine, detomidine and romifidine) have similar speeds of onset followingi.v. administration (approximately 3 min). However, the duration of sedation varies; romifidine provides the longest effect and xylazine the shortest. The dose range is quite broad (see later) and they have a ‘ceiling of effect’. Doses above this ‘ceiling’ will usually prolong the duration of action and increase the untoward side effects such as ileus and ataxia, although the latter is consideredless marked with romifidine. These agents are usually administered as single bolus and repeat doses can be administered for longer procedures (usually >20–30 min). Unfortunately, this can lead to marked swings in the depth of sedation. The continuous infusion of alpha-2 agonists has recently been used in an attempt to achieve a more constant level of sedation - see later. Opioids Opioids are drugsthat act in a similar manner to morphine, and provide potent analgesia. The use of opioids in combination with α2 agonists improves the reliability of the sedation and analgesia. However, when used alone, they may be associated with excitement, manifest as restlessness and box-walking. This can be reduced by administering the α2 agonist first. In most cases, the drugs are administeredsimultaneously. The only opioid licensed for use in horses is butorphanol. Morphine, still the mainstay of human analgesia, is being used increasingly as part of the anaesthetic protocol at some institutions. It is the gold standard opioid analgesic against which others are compared. Morphine is still considered to provide superior analgesia to the other opioids, although there is no supporting clinicalevidence for this for horses. DOSE RATES FOR ALPHA-2 AGONIST + BUTORPHANOL COMBINATIONS Butorphanol i.v. at 0.01–0.03 mg/kg bwt (0.1–0.3 ml per 100 kg of horse) Plus Xylazine i.v. at 0.5–1.0 mg/kg bwt (0.5–1.0 ml 10% soln. per 100 kg of horse) or Detomidine i.v. at 0.01–0.02 mg/kg bwt (0.1–0.2 ml per 100 kg of horse) or Romifidine i.v. at 0.04–0.1 mg/kg bwt (0.4–1.0 ml per 100 kg of horse)
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Proceedings of the 47th British Equine Veterinary Association Congress BEVA
Sep. 10 – 13, 2008 Liverpool, United Kingdom
Next Congress:
Reprinted in IVIS with the permission of the British Equine Veterinary Association – BEVA http://www.ivis.org/
Reprinted in IVIS with the permission of BEVA
Close this window to return to IVISFriday
Hall 1A
16.50–17.10
Sedation strategies for standing surgery
Andrew Harrison
Three Counties Equine Hospital, Stratford Bridge, Ripple, Tewkesbury, Gloucestershire GL20 6HE, UK.
The primary objective is to enable surgery to be performed in the standing horse, by minimising or preferably abolishing movement of the patient in response to both noxious (surgical) and non-noxious(e.g. noise) stimuli. This is achieved by calming the patient usually chemically, and providing adequate analgesia and anaesthesia. Physical restraint is aided by the use of stocks where appropriate. However, it is important to ensure that airway patency is maintained. Blindfolding and the use of cotton wool earplugs may assist in reducing visual and auditory responses (remember to remove theearplugs on completion of the procedure!). Chemical restraint is usually achieved with a combination of pharmacological agents, either as a bolus or as a continuous infusion, in conjunction with any appropriate local anaesthetic techniques. DRUGS AND DRUG COMBINATIONS Phenothiazines Acepromazine maleate, is the most commonly used phenothiazine in equine practice. It produces a mental calming effect inmost animals. Although the degree of sedation is only mild and it provides no analgesia, it is an important part of the anaesthetic protocol. Dose: 0.04 mg/kg bwt i.v. or i.m. Alpha-2 agonists Alpha-2 agonists have a dual action in providing reliable, dose-dependent sedation and good analgesia in most horses. These drugs (xylazine, detomidine and romifidine) have similar speeds of onset followingi.v. administration (approximately 3 min). However, the duration of sedation varies; romifidine provides the longest effect and xylazine the shortest. The dose range is quite broad (see later) and they have a ‘ceiling of effect’. Doses above this ‘ceiling’ will usually prolong the duration of action and increase the untoward side effects such as ileus and ataxia, although the latter is consideredless marked with romifidine. These agents are usually administered as single bolus and repeat doses can be administered for longer procedures (usually >20–30 min). Unfortunately, this can lead to marked swings in the depth of sedation. The continuous infusion of alpha-2 agonists has recently been used in an attempt to achieve a more constant level of sedation - see later. Opioids Opioids are drugsthat act in a similar manner to morphine, and provide potent analgesia. The use of opioids in combination with α2 agonists improves the reliability of the sedation and analgesia. However, when used alone, they may be associated with excitement, manifest as restlessness and box-walking. This can be reduced by administering the α2 agonist first. In most cases, the drugs are administeredsimultaneously. The only opioid licensed for use in horses is butorphanol. Morphine, still the mainstay of human analgesia, is being used increasingly as part of the anaesthetic protocol at some institutions. It is the gold standard opioid analgesic against which others are compared. Morphine is still considered to provide superior analgesia to the other opioids, although there is no supporting clinicalevidence for this for horses. DOSE RATES FOR ALPHA-2 AGONIST + BUTORPHANOL COMBINATIONS Butorphanol i.v. at 0.01–0.03 mg/kg bwt (0.1–0.3 ml per 100 kg of horse) Plus Xylazine i.v. at 0.5–1.0 mg/kg bwt (0.5–1.0 ml 10% soln. per 100 kg of horse) or Detomidine i.v. at 0.01–0.02 mg/kg bwt (0.1–0.2 ml per 100 kg of horse) or Romifidine i.v. at 0.04–0.1 mg/kg bwt (0.4–1.0 ml per 100 kg of horse)
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