Anesthesia

The decision for the type of anesthesia to be used in your surgery, like the decision to perform the surgery itself, is one of risks and benefits. It is usually a joint decision between you and your anesthesiologist, as well as your surgeon. For hip surgery, a combination of general and spinal anesthetics is recommended. For knee surgery, spinal with sedation is recommended.

GENERAL ANESTHESIA
During general anesthesia the patient is unconscious. Light general anesthesia allows the patient to breath on his own; deep anesthesia requires ventilation of the patient by the anesthesiologist. A short case can be done with a mask, but is usually done with an endotracheal tube, which is placed through the mouth or nose into the trachea. Both intravenous and gaseous agents can be used to provide general anesthesia. These agents work on the brain rather than on the spinal cord, as in spinal anesthesia.

The benefits of general anesthesia are that the patient is not aware of what is transpiring and the anesthesia can be prolonged as long as necessary for the procedure. It is also somewhat safer in regards to maintaining adequate oxygenation, when the patient is intubated (has a tube put in the trachea, as discussed above).

Some risks and side effects should be considered. The general anesthetic gaseous agents and the endotracheal tube cause mild irritation of the airway and can cause breathing difficulties after surgery, including a small risk of pneumonia. There is also some grogginess and lethargy as the anesthesia agents slowly clear over several hours post-operatively. General anesthesia can also cause precipitous drops in blood pressure. These can usually be prevented by adequate hydration, but may be a problem in some patients with compromised cardiovascular systems. This lowered blood pressure and possibly lowered perfusion of the brain and heart, can cause (in a very small number of patients) a heart attack or stroke. Post-operative nausea can also occur while the anesthetic agents are cleared from the body over the first few hours following the procedure. This can usually be managed by other medications.

SPINAL ANESTHESIA
This type of anesthesia will completely numb the patient from the waist down. In a spinal anesthetic, a long, thin needle is passed between the vertebrae and enters the spinal canal. The skin and the tract that the needle follows are numbed by the anesthesiologist with a local anesthetic (Lidocaine). Once the spinal canal is entered, a small amount of spinal fluid is withdrawn to be sure that the needle is within the spinal canal. The anesthetic agent is then injected (either Lidocaine, Marcaine or Pontocaine). In addition, for post-operative pain control, a narcotic agent can be injected (Duramorph, Astromorph) and the needle is then withdrawn. The numbing medicine sets up quickly, within a few minutes, and the anesthesiologist checks to see the level of anesthesia which is usually up to approximately the waist level. Depending on the spinal anesthetic used, the numbing effect will usually last three to six hours. The narcotic agent, however, will provide pain control for approximately 12 to 18 hours.

Use of sedatives with amnesic properties given intraveneously allows the patient to be unaware of the procedure and have no memory of the time during the surgery.

Spinal anesthesia has been shown to decrease the blood loss in hip surgeries and possibly decrease the chance of post-operative blood clot formation in the deep veins of the legs and pelvis.

A spinal anesthetic does carry a small risk of spinal headache. This occurs when there is a small leak of spinal fluid through the puncture of the dura. This is uncommon when very fine needles are used. If a spinal headache occurs, the treatment is usually bed rest with the head flat for approximately 24 hours. If the headaches persist, a "blood patch" can be performed by the anesthesiologist where a small amount of the patient’s own blood is injected in the epidural space and this helps to seal-off a dura leak.

The two common side effects from spinals are nausea and itching. Each of these occur approximately 20% of the time and can usually be controlled with other medications.

EPIDURAL ANESTHESIA
This is similar to spinal anesthesia but instead of entered the spinal canal, the needle is place near the canal and a catheter is inserted and the needle removed. The anesthetic and analgesic medications are injected through the catheter and must diffuse through the covering of the spinal canal (the "dura"). Leaving the catheter in place allows for repeat dosing of pain relieving medications after surgery.

We do not use epidural anesthesia for two reasons. First, we have not found it to be as predictably effective as spinal anesthetic. Second, because we start blood thinning medication (i.e. Coumadin) the night before surgery, we are concerned about bleeding around the catheter if it is left in place post operatively. This could cause paralysis.

COMBINATION ANESTHESIA
Using a combination of spinal and general anesthesia can take advantage of the benefits of each and limit the side effects. If a spinal anesthetic is used in addition to a general anesthetic, the amount of general anesthesia required is quite small, because the patient is already numb from the waist down and not receiving any stimulation from the surgery. Therefore, the patient can receive the benefits of spinal anesthesia, such as decreased blood loss, decreased chance of blood clot formation in the deep veins, and post-operative pain control, as well as achieve the safety benefits of general anesthesia, i.e., maintaining adequate ventilation and oxygenation. After the procedure, the patient that has had a combined anesthetic usually wakes up quickly with less of the "hangover" effects of general anesthesia. There is also less irritation to the lungs from the anesthetic agents, resulting in less chance of breathing difficulties and pneumonia afterwards.

There is one increased risk of combined anesthesia and that is an increased chance of having a transient drop in blood pressure. This occurs because of the pooling of the blood in the deep veins caused by the spinal anesthetic, combined with the usual transient drop in blood pressure on induction of general anesthesia. This can usually be avoided in patients with normal cardiovascular systems by maintaining adequate hydration and fluids intravenously. In patients with compromised cardiovascular systems, however, this combination technique may be contraindicated. In these cases, a spinal procedure can be performed, but the narcotics instilled only for postoperative pain management, skipping the anesthetic agent that might cause problems when combined with the general.

MULTI-MODAL PAIN MANAGEMENT
In the past most surgeons used only narcotics (Vicodin, Demerol, Morphine) for post-operative pain. This had certain disadvantages. There was a concern that giving too much narcotic could overly sedate a patient, perhaps even causing respiratory depression which could be life threatening. On the other hand giving too little would not sufficiently relieve pain and allow the patient to function with nursing and physical therapy. Patients would vary in their sensitivity to narcotics (a common side effect of narcotics is nausea and vomiting). Getting the dose just right for each patient, while avoiding side effects, was rarely accomplished with narcotics alone.
Our goal for our patients is to allow them to advance rapidly while remaining very comfortable. The advancements we have made in pain management allow patients to begin therapy quickly and meet their milestones within just a few sessions. Although, every patient progresses at their own pace, we have seen that patients can be discharge home 2 or 3 days after surgery.

The concept behind the use of “multi-modal pain management” is that by combining medications that act at different points in the “pain pathway”, you can effectively relieve pain with fewer side effects. Equally important is the concept of preventing pain before it occurs. In the past when using narcotics alone on an “as needed” (or “prn”) basis the patient had to experience pain before it was treated. This not only resulted in more pain for the patient, but required more pain medication to relieve the pain, thereby increasing the chance of side effects. With multi-modal pain management one “stays ahead of the pain” and the patient experiences less pain and is able to function better and participate in a quicker recovery.
Our current regimen is to use a combination of “scheduled” (i.e. not “prn”) medications like oxycontin, Toradol, Celebrex, tramadol and others which work at different points on the pain pathway. This is combined with the use of regional and local anesthetics as well as spinal narcotics (given in conjunction with the spinal anesthetic) that help to prevent pain after surgery. We still use narcotics on an “as needed” (prn) basis, but they are now used only for “breakthrough” pain, not prevented by the multi-modal technique. Usually this is an oral medication, hydrocodone (Norco or Vicodin), Darvocet, codeine or similar that you may have every 4 hours as needed. As needed, the nurse can give an intravenous narcotic although we have found that often the oral medication lasts longer and creates less nausea. Anti-nausea medication is also given on a scheduled basis to try to avoid that side effect.
Pain is now considered the “fifth” vital sign (the others are temperature, pulse, respirations and blood pressure). After surgery you will be asked frequently by your nurse to rate your pain on a 1 to 10 scale (with 1 being very slight pain and 10 being the worst pain you have ever had). It is usually not possible to eliminate all post-operative pain and discomfort. Our goal for you is to avoid pain levels above the 3-5 range (mild to at most moderate), and if you experience a level above this range, to promptly treat it. The nurses will work with you to “stay ahead of the pain” and to try to time your medications before physical therapy sessions.
With multi-modal pain management, patient-controlled analgesia (PCA), a technique that was popular in the past, is less common in our practice yet is still used in certain situations. In this technique the patient controls when they receive intravenous narcotic pain medicine. The machine that provides this control is attached to an IV. There is a push-button that the patient controls. If you are feeling pain that is excessive to you, you merely push the button and a dose of narcotic pain medication is delivered to your IV. This works very fast and within a minute or two you feel the effect. A computer controls the dose and frequency. Typically the interval allowed is every 10 minutes or greater. If you push the button sooner than that, nothing happens. The computer can also be programmed to provide a baseline infusion (a constant amount of medication) to try to prevent pain from occurring, although there is concern about giving too much medication and depressing respirations, so the baseline infusion is rarely used.
With multi-modal pain management we have found PCA to be counter-productive in most situations. It requires the patient to push the button frequently, since intravenous narcotics are very short acting. That means if you fall asleep for a while you usually wake up in pain, since you haven’t been pushing the button. Also, since this is an intravenous narcotic, there is a high side effect of nausea and vomiting. Patients are frequently either in significant pain or narcotized (sleepy) from getting too much medication. Again, getting the dose right for each patient is difficult. We have found that for most patients, the multi-modal approach is sufficient, and they don’t require frequent intravenous narcotics. If, however, patients come into the hospital already taking significant doses of narcotics, or if we are unable to use spinal anesthesia with spinal narcotics, we will use PCA as an adjunct to our usual multi-modal regimen.
While we cannot guarantee that you will have no pain after surgery, and we do not believe that this is a realistic goal, with multi-modal pain management we have seen less pain, faster recovery, an easier ability to work with physical therapy, and a faster discharge to home.

KNEE SURGERY
If you are having knee surgery, your procedure can be performed under spinal anesthesia, general anesthesia or combined. In these cases, Drs. Bargar and Blumenfeld usually recommend spinal anesthesia alone (with sedation). This is because the patient is in the supine position during the procedure and can ventilate on their own safely. If for some reason there were breathing difficulties, the patient could easily be intubated by the anesthesiologist and the procedure continued with the combination of general and spinal anesthesia.

SUMMARY
In summary, spinal anesthesia has significant advantages in that it can lower blood loss at surgery, decrease the chance of blood clot formation, and provide for post-operative pain control. General anesthesia renders the patient unconscious and, therefore, not aware of the procedure or the passage of time. It also is considered safer in providing controlled ventilation when the patient is placed on his side during hip surgeries.
Drs. Bargar and Blumenfeld recommend a combined anesthetic using general plus spinal for hip surgeries and spinal alone (with sedation) for knee surgery.

The above description of general and spinal anesthesia represents a general description and discussion from the surgeon's viewpoint. The ultimate decision is between the patient and the anesthesiologist. A more complete description of the pros and cons of different types of anesthesia can be provided by a discussion with the anesthesiologist. In most cases, the anesthesiologist will see the patient in the pre-operative holding area just prior to the procedure. Some anesthesiologists call the patient the night before to discuss anesthesia over the phone. If you have particular questions prior to surgery about your anesthesia, an anesthesiologist will meet with you, go over your particular case and make his or her recommendations.