ANESTHETICS-I.V.-Contd...
2.BENZODIAZEPINES
For detailed information regarding benzodiazepines see Post under the heading Anxiolytics in this blog.
In anesthetic practice the most commonly used benzodiazepines are as follows:-
1.Midazolam
2.Diazepam
3.Lorazepam
These agents are used for preoperative sedation, intraoperative sedation for procedure not requiring analgesias such as colonoscopy and cardioversion, and as adjuncts with other agents to produce anesthesia.
Mechanism
As we already know that benzodiazepines bind at their own receptors very adjacent to the GABA-A receptor and thereby enhance the binding of GABA and its effect of chloride ion influx and thereby make neurons to be hyperpolarized which leads to the prevention of the action potential and the result is neuronal relax. Unlike barbiturates that act directly on the GABA, receptors benzodiazepines have slow onset of action.
Midazolam is useful as a preoperative anesthetic as it reduces the post-operative trauma by causing loss of memory of events (Amnesia) to calm the patient. Midazolam has the advantage of faster onset of action, greater potency, and faster elimination when compared with diazepam and other benzodiazepines.
Side Effects
1.Moderate to severe respiratory depression
2.Withdrawal symptoms
3. Contraindicated with opioids as the combination can produce cardiac and respiratory arrest.
Antagonist
Flumazenil is used to reverse benzodiazepine poisoning. As the drug is short-acting and the dose should be repeated every one hour.
3.OPIOIDS
Opioids are opium alkaloids available naturally as morphine and its derivatives.
Most commonly used opioids as anesthetic agents are as follows:-
1.Fentanyl
2.Morphine
Opioids are used as anesthetics in cardiac surgery and other major surgeries in which cardiac reverse is limited.
Fentanyl is more frequently used than morphine because of its greater potency and its lesser impact on the respiratory system than does morphine.
Side Effects
1.I.V.opioids will cause chest block so that expiration is difficult.
2.Respiratory depression
3.Postoperative trauma.
Antagonist
Naloxone is used as an antagonist to reverse opioid poisoning
4.INNOVAR
Innovar is generical droperidol, a butyrophenone, often combined with fentanyl and nitrous oxide to produce neurolept anesthesia, combined analgesia with amnesia.
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