Anesthesia & You

Anesthesia & You

Types of Anesthesia

MAC Anesthesia

MAC stands for Monitored Anesthesia Care. Monitors to evaluate the heart (EKG), oxygenation (Pulse oximeter), and blood pressure are used. With this category of anesthesia, patients can expect to receive sedation, which is usually with a variety of medications administered through an intravenous catheter. These medications are very effective for treating anxiety and pain. A sleepy state, also sometimes called twilight anesthesia, is achieved before the start of the procedure. Breathing tubes are not required as patients continue to breathe without assistance. Supplemental oxygen is usually administered through a plastic facemask or nasal prongs. The medicines administered usually cause a state of amnesia so patients are unlikely to remember much of what happens in the operating room. Since this is not general anesthesia, the patient may find that they can hear voices and experience some sensation. Surgeons often inject local anesthetics to numb the area they are operating on so that the patient will not experience any pain. The level of sedation can be adjusted to the patient's level of comfort.

Benefits - By using MAC anesthesia, the patient can avoid the side effects of general anesthesia. Patients are usually able to leave the recovery room and return home much sooner.

General Anesthesia

This type of anesthesia involves a complete loss of consciousness. Monitors for the heart (EKG), oxygenation (Pulse oximeter), blood pressure, and temperature are used. Supplemental oxygen is given through a facemask. Medications are then given through an intravenous catheter to induce unconsciousness in the patient. After ensuring unconsciousness, a breathing tube is usually inserted in the mouth.

There are two types of breathing tubes that can be used. For procedures that do not involve the muscle of respiration, and where muscle relaxation is not required, a laryngeal mask airway (LWA) is commonly used. This type of breathing tube rests in the throat and does not extend into the trachea (your windpipe). Usually, the patient breathes on his/her own, and a ventilator is not used. The second type of breathing tube is an endotracheal tube (ETT). This plastic tube is inserted into the throat past the vocal cords and into the trachea. A cuff is inflated to form a seal so that oxygen and anesthetic gases can be delivered with a ventilator.

During the procedure, muscle relaxants may be used so the surgeon can gain better access to the operative site. Anesthetic gases, as well as intravenous medications, may be administered throughout the procedure to keep the patient asleep and without pain. At Christiana Care, a special monitor called the BIS© monitor is used to evaluate the level of consciousness during surgery. This helps the anesthesia provider adjust the anesthetic level so the patient does not have intraoperative recall, while also avoiding the over-administration of medicine. The BIS© monitor is placed on the forehead and works by evaluating electroencephalographic (EEG) and eletromyographic (EMG) waves. The chance of intraoperative recall occurring is very small with this monitor in place.

Upon awakening from general anesthesia, the anesthetic gases are turned off and the breathing tube is removed as soon as the patient is breathing on his/her own, and beings to respond appropriately. On rare occasions, or for very extensive procedures, the breathing tube may be left in place until certain criteria are met so that the breathing tube can be removed safely. This may occur in the post anesthesia care unit (PACU), or one of the critical care units.

Benefits - General anesthesia is sometimes the only option available for major operations. This option often provides the best operating conditions for the surgeon. The patient will be completely unconscious and unaware of anything happening in the operating room.

Spinal and Epidural Anesthesia

This type of anesthesia involves placement of local anesthetics to numb the nerves of the spinal canal. This results in numbness of the legs, abdomen, and occasionally the chest area, as well as paralysis of the muscles in these areas.

Spinal Anesthesia: After numbing the skin in the lower back, a very thin needle is inserted to deposit a small amount of local anesthetic in the spinal canal to numb the nerves. The numbness usually lasts about two to four hours. The time period can vary from person to person and will also depend on how much and what kind of local anesthetic is given. The patient will feel warmth or a pins and needles sensation in the legs as the nerves are blocked. Within a few minutes, there will be a loss of sensation to cold or sharp objects. Feelings of light touch and pressure may remain throughout the procedure, which is normal. The patient will be tested for loss of sensation to pain piror to starting the procedure

Benefits - Spinal anesthesia works well in providing good pain control for surgery. Before the patient experiences severe pain, pain medications can be given as the block wears off. Very little local anesthetic is given, so the patient can be wide awake or sedated. Pregnant patients will benefit, as there is minimal medication to interact with the fetus.

Epidural Anesthesia: This is very similar to spinal anesthesia. The major difference is that a catheter is introduced through a needle in the low or mid back. The catheter can remain for several days, providing continuous delievery of local anesthetics, which continue to numb the nerves and provide pain relief to the surgical area. The catheter does not penetrate the membrane covering the spinal canal, so the patient is not at risk for developing a spinal headache unless the membrane is accidentally punctured. Because a catheter is left in place, epidural anesthesia, as opposed to spinal anesthesia, is well suited for long procedures of the lower extremities or where postoperative pain control is desired. At CCHS, epidural anesthesia is commonly used for thoracic surgery, radical prostatectomy, and for obstetric patients in active labor.

Benefits - By using epidural anesthesia, the side effects of general anesthesia can be avoided. Epidural anesthesia is usually a very effective means of postoperative pain control.

Nerve Blocks

Local anesthetics can be injected into specific areas to numb the nerves that provide sensation to the site where surgery is planned. Typical areas that are blocked include:

  • Cervical plexus - Nerves in the neck can be numbed to provide carotid endartectomies to be performed under MAC anesthesia
  • Interscalene - Nerves in the neck can be blocked to numb the shoulder and upper arm. A device called a nerve stimulator, which delivers electrical impulses to the nerves, is used to help ascertain when the needle is close to the nerve. Potential complications specific to this block include: Pneumothorax - This is extremely rare, but collapse of the lung is possible and can occur if the needle punctures it. Alternative nerve block - There are many nerves in the vicinity that can all be blocked. The phrenic nerve innervates the diaphragm, which is the major muscle used for breathing. There are two phrenic nerves, so if one is blocked the other usually is sufficient, although the patient may feel as if he/she has to work a little harder to breathe. The eyelid may also droop and the pupil may be less reactiveas nerves to the eye can also be blocked. Hoarseness may result if the recurrent laryngeal nerve is blocked since this nerve innervates the vocal cords. These side effects will diminish as the block wears off.
  • Axillary - Nerves in the armpit are blocked for surgery in the lower arm
  • Femoral/Sciatic - Nerves in the groin and buttocks are blocked to allow surgery in the knee and leg
  • Popliteal - Nerves behind the knee are blocked to allow surgery in the lower leg
  • Ankle - Nerves in the ankle are blocked to allow surgery in the foot

Benefits - Epidural anesthesia provides good postoperative pain control. The block can last for many hours, so as sensation returns, the patient can take pain medications to control the pain before it becomes severe. Also, general anesthesia is usually not required, so its side effects can be avoided.

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