FACTS FOR LAYPEOPLE: DRUGS ANESTHESIOLOGISTS USE

INTRAVENOUS MEDICATIONS:

1.  PROPOFOL.  Propofol is an intravenous sedative-hypnotic, and the most commonly used general anesthetic medication in the United States.  Because propofol can cause the patient to stop breathing, its use is restricted to physicians who are expert in the management of airway and breathing.  Propofol has ultra-fast onset and offset times, usually causing sleep within seconds of injection.  Because the drug is short-acting, it is often administered by a continuous intravenous drip or infusion When propofol is administered without other anesthetic drugs, the patient usually awakens within minutes of discontinuing the drug.  Propofol does not relieve pain, and most painful surgeries require additional medication(s).

2.  MIDAZOLAM (Brand name VERSED).  Midazolam is a short-acting anxiety-reducing drug of the Valium or benzodiazepine class.  Midazolam is commonly injected as the first drug to begin an anesthetic, because it gives patients a sense of calm, and often gives them amnesia for a period of minutes afterward.  Midazolam is a common drug given during sedation for colonoscopy procedures, because most patients have no awareness during the procedure, even though they are usually awake.

3.  NARCOTICS.  Most surgical procedures cause pain, and narcotic drugs are intravenous pain-relievers.  Commonly used narcotics are morphine, meperidine (brand name Demerol), fentanyl, and remifentanil.  Narcotics have the desired effect of dulling the brain’s perception of pain.  Narcotics cause sleepiness in higher doses, and have the common side-effect of nausea in some patients.  Morphine and Demerol are slower-onset, longer-lasting narcotics, while fentanyl and remifentanil are faster-onset, shorter-acting narcotics.

4.  PARALYZING DRUGS.  Some surgeries and anesthetics require the patient to be paralyzed, i.e. muscles must be rendered flaccid so that the patient can not move.  It is imperative that the patient be given adequate intravenous or inhaled anesthetic drugs first, so that the patient has no awareness that they can not move.  Commone paralyzing drugs are vecuronium, rocuronium, pancuronium, and succinylcholine.  Because paralyzing drugs cause the patient to stop breathing, their use is restricted to physicians who are expert in the management of airway and breathing.  Paralyzing drugs are used by anesthesia providers prior to the placement a breathing tube (endotracheal tube) into the patient’s windpipe (trachea).  Paralyzing drugs are used during certain surgical procedures in which the surgeon requires the patient’s muscles to be relaxed, for example, abdominal surgeries, some throat surgeries, and some surgeries inside the chest.

INHALED ANESTHETICS:

1.  POTENT INHALED ANESTHETICS.  Potent inhaled anesthetics include sevoflurane, isoflurane, and desflurane.  These drugs are liquids, administered via anesthesia vaporizers than turn them into inhaled gases.  They are usually administered in low concentrations (1% to 4% for sevoflurane, 1% to 2% for isoflurane, and 3% to 6% for desflurane), because sustained higher concentrations fo these drugs cause life-threatening depression of heart and breathing functions.  Because potent inhaled anesthetics can cause patients to stop breathing, their use is restricted to physicians who are expert in the management of airway and breathing.

2.  NITROUS OXIDE.  Nitrous oxide is a relatively weak inhaled anesthetic drug, usually administered in concentrations of 50% to 70%.  At these doses, nitrous oxide does cause significant sleepiness, but will not render the patient unconscious.  Nitrous oxide has the advantage of being a quick-onset, quick-offset drug, and it is non-expensive.  Because every patient must inhale a minimum of 21% oxygen, the maximum dose of nitrous oxide is 100 – 21, or 79%.  As a measure of safety, oxygen is usually administered at concentration of at least 30%, which is the reason why administered nitrous oxide concentrations rarely exceed 70%.

LOCAL ANESTHETICS:

1.  LIDOCAINE.  Lidocaine is injected into tissue to block pain at that site.  The onset of local anesthesia occurs within seconds, and the duration is short, usually less than one hour.  Lidocaine can be injected into the back during either a spinal anesthetic or an epidural anesthetic, to numb part of the patient’s body without causing unconsciousness.  Lidocaine can also be injected near major nerves, in what is called a nerve block.  Nerve blocks include injections to numb one arm, one leg, the hand, or the foot.

2. PROCAINE (Brand name Novocaine).  Although the term Novocaine is commonly heard, use of this drug has been largely abandoned, replaced by lidocaine instead.

3. BUPIVICAINE (Brand name Marcaine).  Bupivicaine is injected into tissue to block pain at that site.  The onset of local anesthesia occurs within minutes, and the duration is longer than lidocaine, usually from 2 – 6 hours, depending on the location of the injection.  Bupivicaine can be injected into the back during either a spinal anesthetic or an epidural anesthetic, to numb part of the patient’s body without causing unconsciousness.  Bupivicaine can also be injected near major nerves, in what is called a nerve block.  Nerve blocks include injections to numb one arm, one leg, the hand, or the foot.