Anesthesia for Knee Surgery
At some point before your jsurgery, your consultant and Anaesthetist will raise the issue of anesthesia. Many people will jokingly say, "Just put me out, Doc, and wake me when it's over." But the selection of anesthesia is a major decision that could have a significant impact on your recovery. It deserves careful consideration and discussion with your surgeon and your Anaesthetist.
Several factors must be considered when selecting anesthesia, including:
- Your past experiences and preferences. Have you ever had anesthesia before? What kind? Did you have a reaction to the anesthesia? What happened? How do other members of your family react to anesthesia?
- Your current health and physical condition. Do you smoke? Are you overweight? Do you drink or use recreational drugs? Are you being treated for any condition other than your joint replacement?
- Your reactions to medications. Do you have any allergies? Have you ever experienced bad side effects from a drug? Which drug? What were the side effects? What medications, nutritional supplements, vitamins, or herbal remedies are you currently taking?
- The risks involved. Risks vary, depending on your health and selection of anesthesia, but may include breathing difficulties, blood loss, and allergic reactions. Your surgeon and Anaesthetist will discuss specific risks with you.
- The skill and preferences of your surgical team
Types of Anesthesia
There are three broad categories of anesthesia: general, regional, and local.
You are probably familiar with local anesthesia. This is the kind of anesthesia your dentist uses when repairing your teeth. Local anesthesia numbs only the specific area being treated.
Most joint replacements use use either general or regional anesthesia. General anesthesia affects your entire body. It acts on the brain and nervous system, leaving you in a deep sleep. Usually, it is given by injection or inhalation.
There are several types of general anesthetics which your Anaesthetist will discuss with you.
Regional anesthesia involves numbing a specific area of the body, without affecting your brain or breathing. Because you remain conscious, you will be given sedatives to relax you and put you in a light sleep.
The two types of regional anesthesia used most frequently in joint replacement surgery are spinal blocks and epidural blocks. For surgery below the hip, a combination block that targets the lumbar plexus and the sciatic nerve can numb only one leg.
In a spinal block, the anesthesia is injected into the fluid surrounding the spinal cord in the lower part of your back. This produces a rapid numbing effect that can last for hours, depending on the drug used.
An epidural block uses a small tube (catheter) inserted in your lower back to deliver large quantities of local anesthetics over a longer time period. The epidural block and the spinal block are administered in a very similar location; however, the epidural catheter is placed slightly closer to the skin and farther from the spinal cord.
There are several advantages to using a regional anesthesia during hip or knee replacement surgery. Studies have shown that there is less blood loss during the surgery, and fewer complications from blood clotting afterwards.
Side effects from regional anesthesia include headaches, trouble urinating, and allergic reactions, which could be quite serious.
As with any anesthesia, there are risks, which may be increased if you already have heart disease or a chronic lung condition.
- General anesthesia slows both your heart and breathing rates; therefore, your anaesthetist will constantly monitor your heart, blood pressure, breathing, and body temperature during the surgery.
- General anesthesia also causes your blood vessels to open wider (dilate), which can result in a heavier loss of blood during the surgery. You may want to consider donating blood in advance of your surgery.
- The tube inserted down your throat may give you a sore throat and hoarse voice for a few days.
- Headache, nausea, and drowsiness are also common.