Excerpt from Anesthesia, General

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Anesthesia is the process by which a patient is rendered able to undergo surgery. Surgery was, of course, commonly performed before any means was available to spare the patient any part of the experience. It takes little imagination to realize that an unanesthetized person enduring a surgical wound exhibits the following:

• Evasive action



• Severe pain and emotional distress
  


• Maximum tension in skeletal muscles
  


• Massive increase in sympathetic tone causing sweating, tachycardia, and hypertension
  


• Vivid and unpleasant memory of the event forever

The goals of anesthesia thus include the following:

• Anesthesia (lack of awareness of surrounding events)

• Akinesia (keeping the patient still to allow surgery to take place)

• Muscle relaxation (to enable access through muscles to bones and body cavities)

• Autonomic control (to prevent dangerous surges in hemodynamics)

General anesthesia

General anesthesia uses drugs administered systemically to render the patient unaware of anything that is being done to or around him or her. It must be safe, not threatening or unpleasant to the patient, allow adequate surgical access to the operative site, and cause as little disturbance as possible to internal homeostatic mechanisms. A point worth noting is that general anesthesia, as opposed to local or regional anesthesia, may not always be the best choice. The anesthesiologist selects the optimal technique for any given patient and procedure. Attributes of general anesthesia include the following:

• Advantages
  
  • Makes no psychological demand of the patient
    
  
  
  • Allows complete stillness for prolonged periods of time
    
  
  
  • Facilitates complete control of the airway, breathing, and circulation
    
  
  
  • Permits surgery to take place in widely separated areas of the body at the same time
    
  
  
  • Can be used in cases of sensitivity to local anesthetic agent
    
  
  
  • Can be administered without moving the patient from the supine position
    
  
  
  • Can be adapted easily to procedures of unpredictable duration or extent
    
  
  
  • Usually can be administered rapidly
    


• Disadvantages
  
  
  • Requires the involvement of an extra set of healthcare providers
    
  
  
  • Requires complex and costly machinery
    
  
  
  • Requires some degree of preoperative patient preparation
    
  
  
  • Usually associated with some degree of physiological trespass
    
  
  
  • Carries the risk of major complications including death, myocardial infarction, and stroke
    
  
  
  • Associated with less serious complications such as nausea or vomiting, sore throat, headache, shivering, and delayed return to normal mental functioning
    
  
  
  • Associated with malignant hyperthermia, a rare, inherited muscular condition in which exposure to some (but not all) general anesthetic agents results in acute and potentially lethal temperature rise, hypercarbia, metabolic acidosis, and hyperkalemia

A given patient's risk for complications as a direct result of general anesthesia is small but depends largely on his or her medical comorbidities.

Death attributable to anesthesia is said to occur at rates of less than 1:10,000, but these are average figures incorporating both elective and emergency patients with all types of physical conditions. Minor complications occur at predicable rates, even in previously healthy patients. The frequency of symptoms during the first 24 hours following ambulatory surgery is as follows:

• Bleeding, vomiting, nausea - Less than 5%
  


• Fever - 5-15%
  


• Dizziness, headache, drowsiness, hoarseness - More than 15%
  


• Sore throat - 25%
  


• Incisional pain - 30%

An excellent recent review of the literature concerning anesthesia-related morbidity and mortality will be of interest to readers wanting more information.¹

Please click here to view the full topic text: Anesthesia, General