Anesthesia for total knee arthroplasty
Before undergoing total knee arthroplasty, the physician discusses in detail with the patient the available options for anesthesia. The right choice of anesthesia is an important parameter that can affect recovery; therefore, a careful discussion with the orthopedist and anesthetist is deemed necessary.
Several factors should be considered when choosing anesthesia, including:
- Past experiences and preferences. It should be known whether the patient has previously undergone anesthesia, whether or not there was an adverse reaction and how other family members respond to anesthesia.
- The current state of the patient’s health; smoking habits, obesity or administered medication for another condition.
- Drug reactions; allergies or any side-effects caused by medication. In addition, what kind of medicines, vitamins, minerals or dietary supplements the patient receives.
- Possible risks. The risks vary depending on the general state of the patient’s health and the choice of anesthesia and generally include respiratory difficulties, allergic reactions and nerve damage. The surgeon and the anesthesiologist will discuss the specific risks with the patient.
TYPES OF ANESTHESIA
There are many different types of anesthesia: Local, regional and general anesthesia
In local anesthesia, analgesia is caused only in the part where the anesthetic is injected or sprayed or even where the ointment is applied and lasts only for a certain short period of time. Patients remain awake throughout the anesthesia. It is mainly used for minor operations. For larger operations, such as total knee or hip arthroplasty, local anesthesia is used to supplement the main anesthesia.
Anesthesia of this type involves the “blocking” of nerves, which results in the analgesia of the area of distribution of the certain nerve stem, without affecting respiratory or brain function. Since the patients are awake, relaxing or sedative medications are administered for them to sleep. The 3 main types of anesthesia most commonly used are dorsal anesthesia, epidural anesthesia and peripheral nerve blocking.
In dorsal anesthesia, the anesthetic drug is injected into the cerebrospinal fluid that surrounds the spinal cord and the nerves in the lower part of the body, thereby causing rapid analgesia, which lasts for several hours.
In epidural anesthesia, a catheter is inserted in the lower part of the patient’s spine, for the anesthesiologist to administer anesthetic medication for a specific period of time in the epidural space. Epidural and dorsal anesthesia are administered in a similar manner and in a similar anatomical position
Blocking of peripheral nerves. The peripheral nerve blocking delivers an anesthetic drug directly around the central nerves distributed in the patient’s thigh, such as the femoral or sciatic nerve. They block the nerves only in the diseased leg and not on the other side. Depending on the case, the block may be injected to numb the area that will be operated only during surgery, or to keep the catheter continuously administering anesthetic drug for several days after surgery.
Benefits of regional anesthesia include a lower risk of bleeding, fewer cases of nausea, dizziness, and lower risk of medical complications, such as a cardiac arrest or ischemic or hemorrhagic stroke (which may be rare). Side-effects due to regional anesthesia may include headache, nausea (postoperative difficulty in urination), allergic reactions and rarely nerve damage.
General anesthesia is mainly used in major surgeries, such as total knee arthroplasty. General anesthesia can be selected on the basis of the patient’s or surgeon’s preference or where local anesthesia cannot be used. Unlike other types of anesthesia, general anesthesia affects the patient’s entire body, brain and nervous system and renders him/her temporarily unconscious.
- In general anesthesia, the anesthesiologist administers an anesthetic drug by injection or inhalation. A ventilation tube (intubation) will also be inserted to facilitate the patient’s breathing.
- As with any type of anesthesia, there are risks if the patient suffers from heart disease, chronic respiratory problems and other serious problems.
General anesthesia affects both cardiac and respiratory function and there is a small chance of serious complications, such as myocardial infarction or stroke. The ventilation tube may cause sore throat or sensitivity due to irritation of the vocal cords. Other common symptoms are nausea, headache and dizziness.
The goal of postoperative analgesia is to minimize discomfort and pain, so that the patient can participate freely and actively in the postoperative physiotherapy protocol. Postoperative analgesia may be achieved by oral medication or in combination with intravenous treatment. A modern method of analgesia is injections performed by the patient himself. In this way the patient controls the intravenous flow of the drug, within safe limits set by the physician.
If regional anesthesia is used, the special catheter can remain in place and continue the infusion of the drug during the first postoperative days.
Finally, proper use of painkillers after surgery is extremely important for the recovery of the patient. It encourages and assists in the final recovery after surgery.