What is anesthesia?
Anesthesia means "without sensation" or a "reversible lack of awareness".
Your anesthesiologist will personally medically assess you prior to your surgery or non-surgical procedure and determine the best type of anesthesia to use in your specific case.
Types of anesthesia include:
This is the most common type of anesthesia. You will have a total lack of awareness. Essentially you will be "completely asleep". The anesthetic drugs and vapors administered will result in you becoming "unconscious" for the entire duration of your surgery or procedure. After you emerge or "wake up" from general anesthesia you will have no recall of any events from the time you were induced or "put to sleep" into general anesthesia. In fact, general anesthesia is a drug coma induced and controlled by your anesthesiolgist during which your anesthesiologist will monitor and care for your well being, allowing you to emerge at the appropriate time.
There are 3 main components to general anesthesia:
- Hypnosis. You are unaware of anything happening during general anesthesia.
- Analgesia. You will be pain free from the administration of anesthesia or IV pain medications.
- Muscle relaxation. Your muscles are sometimes relaxed to facilitate placement of your breathing tube or to help your surgeon by keeping you still, or to aid in the procedure itself.
This is most commonly administered for obstetric anesthesia and analgesia and orthopedic anesthesia and analgesia, although regional techniques can be used in a large number of other specialties such as general surgery and gynecologic surgery. Here a specific region of your body will be without sensation or pain.
Neuraxial regional anesthesia
In Neuraxial regional anesthesia (consisting of both spinal and epidural anesthesia) local anesthetic is placed into the back. In spinal anesthesia the injection of local anesthetic will be into the subarachnoid space (where there is spinal fluid). It is usually administered in the lower back and will lead to the abdomen and legs to become numb and heavy for 2-3 hours. In Epidural anesthesia, a small catheter is carefully placed into the epidural space (located just outside the subarachnoid space). Local anesthetic solution injected into the catheter will also result in loss of sensation and pain in the abdomen and/or legs. This is the primary analgesic chosen by pregnant women for the pain of labor and childbirth, although it can also be used for other types of procedures such as abdominal surgeries and lung surgeries, usually to provide postoperative pain control. Here the epidural catheter is placed higher up in the mid-lower back to numb up those specific areas.
Peripheral Nerve Blocks and Bier Blocks
The second common category of regional anesthesia encompasses all peripheral nerve blocks and Bier blocks (IV regional anesthesia). For peripheral nerve blocks, which we usually use for postoperative pain management, local anesthetic solution is injected around a nerve(s) to numb up a specific limb or region. For example for shoulder surgery, injection of local anesthetic in the neck around the nerves supplying the shoulder and arm on that side will provide excellent analgesia for 8-24 hours postoperatively. Other types of peripheral nerve blocks including numbing the knee at the level of the groin or numbing the foot and ankle at the level of the knee. We utilize the latest techniques such as peripheral nerve stimulation and ultrasonography to help us localize the nerves to be anesthetized quickly and safely. In addition for hand or arm surgery of short duration, we offer IV regional anesthesia or Bier blocks. This involves injecting local anesthetic into an IV in that hand with a tourniquet on, to numb up the entire arm. This type of regional anesthesia usually lasts for a short duration, and is therefore used for the surgery itself, and not for postoperative pain control.
TIVA (Total IV Anesthesia) or IV General
Total IV Anesthesia is a form of anesthesia where you will effectively be given a general anesthetic (see above) without the placement of a breathing tube. You will not be placed on a ventilator and will be breathing on your own. The difference between deep sedation and TIVA is you will be unconscious and not rousable to stimulation with an IV general. We use this technique for a number of procedures, but most commonly for gastroenterology procedures such as upper endoscopy and colonoscopy, performed by the gastroenterologists and transesophageal echocardiography performed by the cardiologists. This technique is also used in conjunction with other types of anesthesia such as local anesthesia and regional anesthesia (for example spinal anesthesia for total knee replacements or eye blocks for retinal surgery).
MAC or Monitored Anesthesia Care with Sedation: Deep, Moderate, Mild
Monitored anesthesia care with sedation is usually used in conjunction with other techniques such as local anesthesia for cataract surgery and regional anesthesia such as Bier blocks. In mild sedation you will be awake but relaxed with medication. You will be able to follow commands. In moderate sedation you will be somewhat more relaxed and will be rousable to command or touch. In deep sedation you will be asleep but still rousable to deep stimulation. Very occasionally MAC without sedation is requested by your doctor. Here, an anesthesiologist will be closely monitoring your vital signs and will be immediately available should the need for sedation or other types of anesthesia arise.
Here, the anesthetic or numbing medicine is directly infiltrated into the surgical site. A common example is local anesthesia for dental surgery or eye drops for cataract surgery. In the hospital setting, local anesthesia is usually only part of your anesthesia care, which usually also involves MAC with sedation, TIVA or General Anesthesia in addition to the local.