General Anesthesia Requirements

During major surgery (such as laparotomy, thoracotomy, joint replacement, amputation), the patient should 

Amnesia (i.e., no recollection of what occurred during the surgery). 

Skeletal muscle relaxation (this requirement is currently met with the aid of skeletal muscle blockers used in conjunction with the anesthetic [see Neuromuscular Blockers, later]). 

A minimum of toxic side effects (i.e., be relatively safe). 

Rapid onset of anesthesia easy adjustment of the anesthetic dosage during the procedure and rapid, uneventful recovery after administration is terminated. 

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The administration of general anesthesia requires the use of one or more drug . The choice of anestiietic drug depends on many factors, including... 

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. 

Water-soluble contrast media (CM) are preferred because of effective mixing with CSF, plus the radiopaque is absorbed and effectively excreted in the urine, and does not have to be physically removed from the subarachnoid space after the procedure. Sodium methiodal, the first water-soluble agent used for myelography, produced neurotoxicity problems when exposed to the cells of the spinal cord and brain, thus limiting utility to the lumbar region and requiring the appHcation of spinal or general anesthesia. 

Although the use of barbiturates and miscellaneous sedatives and hypnotics for sedation has largely been replaced by the antianxiety drugs (see Chap. 30), they occasionally may be used to provide sedation before certain types of procedures such as cardiac catheterization or the administration of a local or general anesthesia Sedative doses usually given during daytime hours, may be used to treat anxiety and apprehension. Fhtients with chronic disease may require sedation, not only to reduce anxiety, but also as an adjunct in the treatment of their disease... 

RBC transfusions are indicated for acute exacerbation of baseline anemia (e.g., aplastic crisis, hepatic or splenic sequestration, severe hemolysis), severe vasoocclusive episodes, and procedures requiring general anesthesia or ionic contrast. Transfusions might be beneficial in patients with compli-... 

Naloxone (Narcan). Naloxone, like naltrexone, is a potent opioid receptor blocker. Its primary use has been to reverse opiate toxicity after an overdose. However, some physicians have found it is also useful for a process known as rapid opiate detoxification. Although opiate withdrawal is not life threatening, it can be extremely unpleasant. Most opiate addicts are fearful of the withdrawal symptoms therefore, it usually requires a slow, deliberate detoxification to keep the withdrawal symptoms in check. Rapid opiate detoxification is an alternative approach that keeps the taper and detoxification as brief as possible. In this approach, naloxone is used in conjunction with general anesthesia or a nonopiate sedative such as the benzodiazepine mid-... 

Bone marrow is the natural site of hematopoiesis and was therefore the first source of hematopoietic stem and progenitor cells. In addition to the hematopoietic cells primary stroma can also be collected simultaneously from this source. However, as the harvesting of cells from bone marrow is an invasive procedure that requires manual extraction under spinal or general anesthesia, alternative sources are preferred whenever possible, although, for allogeneic stem cell transplantation, bone marrow is still the source of choice [23]. 

An anxious 5-year-old child with chronic otitis media and a history of poorly controlled asthma presents for placement of ventilating ear tubes. General anesthesia is required for this short elective ambulatory surgery procedure. What preanesthetic medication should be administered Which of the three commonly used anesthetic techniques would you choose to use in this situation (1) inhalational anesthesia with sevoflurane for induction and maintenance in combination with nitrous oxide, (2) intravenous anesthesia with propofol for induction and maintenance of anesthesia in combination with remifentanil, or (3) balanced anesthesia using propofol for induction of anesthesia followed by a combination of sevoflurane and nitrous oxide for maintenance of anesthesia ... 

Many diagnostic, therapeutic, and minor surgical procedures require neither general anesthesia nor the availability of specialized equipment and facilities necessary for inhaled anesthesia. In this setting, regional or local anesthesia supplemented with midazolam or propofol and opioid analgesics may be a more appropriate and safer approach than general anesthesia. 

General anesthesia is needed to perform hypothermia therapy. Without general anesthesia, the cerebral temperature cannot be lowered satisfactorily because of shivering, which usually starts at levels of 35°C. The requirement of anesthesia limits the indications for therapy. From an ethical viewpoint, general anesthesia may be permitted only in patients with consciousness disturbance. Hypothermia may be best indicated for patients with embolic occlusion of major cerebral arteries,... 

The surgical placement of vascular catheters and the instillation of bacteria, either intratracheally or intraperitoneally, require general anesthesia. Anesthesia is induced with a combination of ketamine and xylazine and maintained with additional doses of ketamine as needed. During the surgical procedure the rabbit breathes spontaneously through an endotracheal tube (3.0 mm ID, 4.2 mm OD, Kendall/Sheridan, Argyle, NY). 

At therapeutic doses, tricyclic antidepressants can cause postural hypotension, but they are regarded as being safe in patients who require general anesthesia. However, hypotension during surgery has been associated with clomipramine (12). 

In 113 patients undergoing general anesthesia, intravenous midazolam 15 mg slowed recovery of the twitch height after vecuronium and atracurium compared with diazepam. The recovery index was not altered (162). However, in another study in 20 patients, midazolam 0.3 mg/kg did not affect the duration of blockade, recovery time, intensity of fasciculations, or adequacy of relaxation for tracheal intubation produced by suxamethonium 1 mg/kg, nor the duration of blockade and adequacy of relaxation for tracheal intubation produced by pancuronium 0.025 mg/kg in incremental doses until 99% depression of muscle-twitch tension was obtained (161). Furthermore, in 60 patients undergoing maintenance anesthesia randomly assigned to one of six regimens (etomidate, fentanyl, midazolam, propofol, thiopental plus nitrous oxide, or isoflurane plus nitrous oxide), midazolam did not alter rocuronium dosage requirements (165). 

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