Local vs General Anesthesia
Anesthesia is a medical procedure where pain sensation is removed with special drugs. Anesthesia is very important to allow various surgical procedures either minor or major. There are specially trained doctors called anesthetists who anesthetize patients for surgery. Anesthesia involves interrupting autonomic body functions for a time and maintaining the patient with drugs till the surgery is over. To accomplish these anesthetists need a sound knowledge of physiology and pharmacology. Anesthesia can be divided into three components. They are local anesthesia, regional anesthesia, and general anesthesia. In this article, we will discuss the differences between local and general anesthesia.
Local anesthesia involves numbing up a small area of skin for a minor procedure or relieving pain arising from a local disease condition. There are no special preparations required for local anesthesia; excluding allergies is enough. Surgeries like suturing a cut injury needs injectable drugs to remove pain sensation at the wound site. Patients with anal fissures or thrombosed piles may need rectal inserts of local anesthetic drugs to relieve pain. There are special drugs that remove the sensation from a localized area of skin. These are called local anesthetic drugs. In olden days, drugs removed all the sensations from an area of skin. With recent developments, new drugs have come into use which remove certain sensations selectively.
There are many types of sensations perceivable by the skin. Simple sensations are pain, temperature, light touch, and deep pressure. These are transmitted along the spino-thalamic tract of the spinal cord. Two point discrimination, vibration, and joint position sensation are complex sensations carried up to the brain along the dorsal column of the spinal cord. Local anesthetics only affect the spino-thalamic sensations and not the dorsal column sensations. There are four major types of nerves in the body. Pain sensation is carried along C type fibers which are thin, sensitive to local anesthetics and resistant to pressure. Local anesthetics affect pain fibers first because they are thin. Marcaine, Lignocaine and xylocaine are some local anesthetic drugs.
Complications of local anesthesia are rare. Accidental injection of local anesthetic into an artery, peripheral vasoconstriction, and allergies are the most frequently reported complications.
General anesthesia involves lowering the conscious level of the patient. Special preparations are necessary to ensure safe anesthesia. Most major surgeries require general anesthesia. There are some surgeries that can be done under regional anesthesia, as well. Some gynecological surgeries like vaginal hysterectomy would be easier under general anesthesia than regional anesthesia because ligaments relax better under general anesthesia.
Anesthetist examines the patient before a surgery to exclude heart, lung, kidney, and liver pathologies as well as allergies. Throat need to be assessed due to the need of intubation. Very infirm, extremes of age, severe heart, lung, kidney, and liver conditions may contraindicate general anesthesia. Once the patient is declared fit for general anesthesia, the surgical procedure goes ahead. Overnight fasting is necessary to ensure an empty stomach. Otherwise, food may regurgitate up along the esophagus and enter lungs. Because the patient is unconscious, the protective mechanisms do not function to keep the airways clear. The result of regurgitation is aspiration pneumonia.
Drugs like ketamine, propofol, nitrous oxide, halothane, thiopentone sodium are some general anesthetic drugs. Neuromuscular junction blockers like suxamethonium and atracurium decouple nerve- muscle linkage relaxing the patient’s muscles to allow easy surgical access. As the respiratory muscles are paralyzed by suxamethonium, artificial ventilation via an endotracheal tube is essential. During the procedure, all the vitals are closely monitored and maintained by the anesthetist. After the surgery is finished, the patient is recovered with special drugs. It is the responsibility of the anesthetist to ensure proper pain relief after surgery. Aspiration, hypoxia, hypotension, allergies, heart arrhythmias, dehydration, and electrolyte imbalances are a few common complications of general anesthesia.
What is the difference between Local and General Anesthesia?
• Local anesthesia involves desensitizing a small skin area while general anesthesia involves putting the whole patient under.
• General anesthesia requires special preparation while local anesthesia does not.
• Complications of local anesthesia are rare while it is not so with general anesthesia.