Surgical anesthesia

It is used in hypotensive shock for the purpose of elevating blood pressure, which can result from spinal anesthesia, surgical complications, and head trauma. Synonyms of metaraminol are aramine, isophenylephrin, metaradine, and others. 

Gravenstein, J. S., How Does Human Error Affect Safety in Anesthesia , Surgical Oncology Clinics of North America, Vol. 9, No. 1,2000, pp. 81-95. 

Historical Inhalation Agents. Diethyl ether produces excellent surgical anesthesia, but it is flammable (see Ethers). Chloroform is a nonflammable, sweet smelling, colorless Hquid which provides analgesia at nonanesthetic doses and can provide potent anesthesia at 1% (see Chlorocarbons AND CHLOROHYDROCARBONs). However, a metabohte causes hepatic cell necrosis. Tdlene, a nonflammable colorless Hquid, has a slower onset and recovery and a higher toxicity and chemical reactivity than desirable. Cyclopropane is a colorless gas which has rapid induction (2 —3 min) and recovery characteristics and analgesia is obtained in the range of 3—5% with adequate skeletal muscle relaxation (see Hydrocarbons). The use of cyclopropane has ceased, however, because of its flammabiHty and marked predisposition to cause arrhythmias. 

Isoflurane is a respiratory depressant (71). At concentrations which are associated with surgical levels of anesthesia, there is Htde or no depression of myocardial function. In experimental animals, isoflurane is the safest of the oral clinical agents (72). Cardiac output is maintained despite a decrease in stroke volume. This is usually because of an increase in heart rate. The decrease in blood pressure can be used to produce "deHberate hypotension" necessary for some intracranial procedures (73). This agent produces less sensitization of the human heart to epinephrine relative to the other inhaled anesthetics. Isoflurane potentiates the action of neuromuscular blockers and when used alone can produce sufficient muscle relaxation (74). Of all the inhaled agents currently in use, isoflurane is metabolized to the least extent (75). Unlike halothane, isoflurane does not appear to produce Hver injury and unlike methoxyflurane, isoflurane is not associated with renal toxicity. 

Chloroprocaine hydrochloride [3858-89-7] is characterized by low potency, rapid onset, short duration of action, and low systemic toxicity. It is indicated for infiltration anesthesia at 1—2% and for extradural anesthesia at 2—3% when short surgical procedures are performed under regional anesthesia. Chloroprocaine may be mixed with long duration agents such as bupivacaine (22, R = n-Q [) to afford a more rapid onset and shorter duration of action than bupivacaine alone. 

Clinical evaluation is underway to test transvenous electrodes. Transvenous leads permit pacemakers to be implanted under local anesthesia while the patient is awake, greatly reducing recovery time and risk. As of 1996, the generation of implantable defibrillators requires a thoracotomy, a surgical opening of the chest, in order to attach electrodes to the outside of the heart. Transvenous electrodes would allow cardiologists to perform pacemaker procedures without a hospital or the use of general anesthesia. 

Anesthesia Anesthesia is a loss of sensation or feeling. Anesthesia (or "anesthetics") is often used deliberately by doctors and dentists to block pain and other sensations during surgical procedures. Treatment for pre- or postoperative pain is called analgesia. 

Etomidate (Amidate), a nonbarbiturate, is used for induction of anesthesia Etomidate also may be used to supplement other anesthetics, such as nitrous oxide, for short surgical procedures. It is a hypnotic without analgesic activity. 

Midazolam (Versed), a short-acting benzodiazepine CNS depressant, is used as a preanesthetic drug to relieve anxiety for induction of anesthesia for conscious sedation before minor procedures, such as endoscopic procedures and to supplement nitrous oxide and oxygen for short surgical procedures. When the drug is used for induction anesthesia, the patient gradually loses consciousness during a period of 1 to 2 minutes. 

Sevoflurane (Ultane) is an inhalational analgesic. It is used for induction and maintenance of general anesthesia in adult and pediatric patients for inpatient and outpatient surgical procedures. 

Ketamine (Ketalar) is a rapid-acting general anesthetic. It produces an anesthetic state characterized by profound analgesia, cardiovascular and respiratory stimulation, normal or enhanced skeletal muscle tone, and occasionally mild respiratory depression. Ketamine is used for diagnostic and surgical procedures that do not require relaxation of skeletal muscles, for induction of anesthesia before the administration of other anesthetic drugp, and as a supplement to other anesthetic drags. 

Baboons were surgically prepared with chronically indwelling silastic catheters implanted in either femoral or jugular veins under pentobarbital or halothane anesthesia using methods described in detail by Lukas et al. 

A large-diameter multihole urethral catheter should be inserted to facilitate saline lavage and evacuation of blood clots. Surgical removal of blood clots under anesthesia may be required if saline lavage is ineffective. Active bleeding from isolated areas may be cauterized with an electrode or laser. In severe cases that are unresponsive to local or systemic pharmacologic intervention,... 

The primary site of action of epidurally administered agents is on the spinal nerve roots. As with spinal anesthesia, the choice of drug to be used is determined primarily by the duration of anesthesia desired. However, when a catheter has been placed, short-acting drugs can be administered repeatedly. Bupivacaine is typically used when a long duration of surgical block is needed. Lidocaine is used most often for intermediate length procedures chloroprocaine is used when only a very short duration of anesthesia is required. 

Uhing, M. R., Kimura, R. E., The effect of surgical bowel manipulation and anesthesia on intestinal glucose absorption in rats, /. Clin. Invest. 1995, 95, 2790-2798. 

Antimicrobials should be delivered to the surgical site prior to the initial incision. They should be administered with anesthesia, just prior to initial incision. Antibiotics should not be prescribed to be given on-call to the OR. ... 

In an undated study, HCFC-141b was administered to male SpragueDawley rats at concentrations of 5,000, 10,000, or 20,000 ppm for 30 min (Eger, unpublished data). As exposure continued, bolus intravenous epinephrine, characterized as three times the dose that produced arrhythmias in the same rats anesthetized with halothane, was administered. The dose of epinephrine was defined as a maximum of 12 fig/kg. For this study, three or more premature ventricular contractions was considered an arrhythmic response (Table 4—5). Marked arrhythmias occurred at all concentrations. The author further compared the concentrations of halothane and HCFC-141b that produced arrhythmias with administration of various doses of exogenous epinephrine. The nominal chamber concentration for HCFC-141b did not differ from that of halothane. Furthermore, the arrhythmias were characterized as relatively mild and within acceptable limits for surgical anesthesia in humans. 

Laborit replaces promethazine with chlorpromazine for pre-surgical anesthesia. 

Cardiovascular Effects. There have been several reports of cardiac arrhythmias associated with application of phenol solutions to the skin in connection with the surgical procedure of skin peeling (Gross 1984 Truppman and Ellenby 1979 Warner and Harper 1985). In this procedure, a mixture of phenol ( 50% w/v), hexachlorophene, and croton oil is applied to the skin while the patient is under anesthesia. In a series of 54 patients in which the whole face was peeled in 1 day, cardiac arrhythmias were reported in 39%, while in a series of patients in which half the face was treated on 1 day, and the second half was treated 24 hours later, cardiac arrhythmias were reported in 22% (Gross 1984). The study author also indicated that the arrhythmias were less severe in the patients treated over a longer period of time. 

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