Anaesthesiologists may prescribe or administer a premedication prior to administration of a general anaesthetic. Anaesthetic premedication consists of a drug or combination of drugs that serve to complement or otherwise improve the quality of the anaesthetic.
One example of this is the preoperative administration of clonidine, an alpha-2 adrenergic agonist. Clonidine premedication reduces the need for anaesthetic induction agents, as well as the need for volatile anaesthetic agents during maintenance of general anaesthesia, and the need for postoperative analgesics. Clonidine premedication also reduces postoperative shivering, postoperative nausea and vomiting and emergence delirium. In children, clonidine premedication is at least as effective as benzodiazepines, in addition to having a more favourable side effect profile. It also reduces the incidence of post-operative delirium associated with sevoflurane anaesthesia. As a result clonidine has become a popular agent for anaesthetic premedication. Drawbacks of oral clonidine include the fact that it can take up to 45 minutes to take full effect, hypotension and bradycardia.
Midazolam, a benzodiazepine characterized by a rapid onset and short duration relative to other benzodiazepines, is effective in reducing preoperative anxiety, including separation anxiety associated with separation of children from their parents and induction of anaesthesia. Dexmedetomidine and certain atypical antipsychotic agents are other drugs that are used in particular in very uncooperative children.
Melatonin has been found to be effective as an anaesthetic premedication in both adults and children due to its hypnotic, anxiolytic, sedative, antinociceptive, and anticonvulsant properties. Unlike midazolam, melatonin does not impair psychomotor skills or adversely affect the quality of recovery. Recovery is more rapid after melatonin premedication than with midazolam, and there is also a reduced incidence of post-operative agitation and delirium. Melatonin premedication also reduces the required induction dose of propofol and thiopental.
Another example of anaesthetic premedication is the preoperative administration of beta adrenergic antagonists to reduce the incidence of postoperative hypertension, cardiac dysrhythmia or myocardial infarction. One may choose to administer an antiemetic agent such as droperidol or dexamethasone to reduce the incidence of postoperative nausea and vomiting, or subcutaneous heparin or enoxaparin to reduce the incidence of deep vein thrombosis. Other commonly used premedication agents include opioids such as fentanyl or sufentanil, gastrokinetic agents such as metoclopramide, and histamine antagonists such as famotidine.
Non-pharmacologic preanaesthetic interventions include playing relaxing music, massage, and reducing ambient light and noise levels in order to maintain the sleep-wake cycle. These techniques are particularly useful for paediatric and mentally retarded patients. Other options for children who refuse or cannot tolerate pharmacologic premedication include interventions by clowns and child life specialists. Minimizing sensory stimulation or distraction by video games may also help to reduce anxiety prior to or during induction of general anaesthesia.
Read more about this topic: General Anaesthesia