Download ANESTHESIA MEDICATIONS

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"ANESTHESIA MEDICATIONS"
"Sub-topics"
Induction medications
Analgesics
Muscle relaxants
Inhalational anesthesia agents
Anti-emetics
Other medications
Local anesthesia
"Many people think that having anesthesia consists of just a needle, which the
anesthesiologist injects to make you ‘go to sleep’; after this the anesthesiologist leaves
you and you ‘wake up’ when the operation is over. In fact, as well as constantly looking
after you during your anesthesia, your anesthesiologist gives you quite a few medications
– usually somewhere between three and fifteen – all for different reasons.
There are four main types of medications used in general anesthesia:
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induction medications to produce unconsciousness
analgesics to provide pain relief
muscle relaxants to induce muscle relaxation
inhalational anesthesia agents to keep you unconscious.
Other medications which are given include:
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medications that produce short-term memory loss or amnesia
medications that minimise nausea and vomiting (anti-emetics)
medications that counter-act the effect of other medications (antagonists)
and medications that suppress certain nervous reflexes, such as slowing of the
heart.
Also, some patients may not have general anesthesia but may remain conscious, with part
of their body made numb by the use of local anesthesia.
Induction medications
These medications include thiopentone or pentothal (which was introduced in the 1930s),
and propofol. When given by intravenous injection, these medications quickly make you
unconscious. This rapid loss of consciousness makes the induction of anesthesia much
more pleasant than previously, when patients had to breathe ether or chloroform.
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Analgesics
These medications, also known as pain-relievers, are mostly opiates or narcotics. They
are either derived from the opium poppy (such as morphine) or are synthesised in a
laboratory (such as pethidine or meperidine (Demerol), anileridine, fentanyl, alfentanil,
sufentanil, and remifentanil).
Muscle relaxants
These medications work specifically to weaken or relax most of the (voluntary) muscles
of the body. However, they do not affect the muscles of the heart, nor those of the
intestines. Before muscle relaxants were introduced in the 1940s, patients had to be given
large amounts of anesthesia medications to ensure that they were deeply anesthetized.
This was necessary to cause their muscles to relax so that the surgeon could operate
within the abdomen, or perform other delicate surgery. Now, with the use of muscle
relaxants, patients do not have to receive very large amounts of anesthesia medications
nor be so deeply anesthetized. This helps to reduce the side-effects of anesthesia. Muscle
relaxants include suxamethonium (or succinyl choline), pancuronium, atracurium,
vecuronium, and rocuronium.
Inhalational anesthesia agents
These medications keep you unconsciousness during the operation. They can also be used
to induce anesthesia, especially in small children. These medications are called
inhalational agents because you inhale them or breathe them in. In the 1950s, a new
inhalational agent, halothane, was introduced and rapidly replaced the older agents such
as ether. Halothane has now been largely superseded by even better inhalation
medications, and the commonly used agents include enflurane, isoflurane, sevoflurane,
and desflurane.
Anti-emetics
These medications help reduce nausea and vomiting and so are termed anti-nauseants or
anti-emetics. They include droperidol, Stemetil, Gravol, and ondansetron.
Other medications
Your anesthesiologist may use other medications to decrease the chance of you
remembering anything that happens in the Operating Room. These medications include
diazepam and midazolam, which belong to the class of medications known as
benzodiazepines. Some medications are given to counteract the effects of other
medications. These include naloxone, to counter the effects of an opiate or narcotic;
flumazenil, to counter the effects of a benzodiazepine; and neostigmine, to reverse the
actions of most of the muscle relaxants. Medications which are used to change your heart
rate include atropine (to increase it) and esmolol (to decrease it). Other medications can
raise your blood pressure (epinephrine or adrenaline) or lower it (nitroprusside).
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Local anesthesia
Injection of local anesthesia around a nerve or a group of nerves temporarily blocks the
transmission of the electrical impulses in the nerve. The lack of transmission causes the
area of the body supplied by the nerve to become numb. This is also known as a ‘sensory
block’, which may progress to muscle weakness, depending on the concentration and
dose of local anesthesia used."
Source:
All About Anesthesia. (2011). About anesthesia. Retrieved October 10, 2011, from
http://www.allaboutanesthesia.com/index.php?option=com_content&view=article&id=1
&Itemid=28