Post-surgical pain is a complex response to tissue trauma during surgery that stimulates hypersensitivity of the central nervous system. The result is pain in areas not directly affected by the surgical procedure. Post-operative pain may be experienced by an inpatient or outpatient. It can be felt after any surgical procedure, whether it is minor dental surgery or a triple-bypass heart operation.
Post-operative pain increases the possibility of post-surgical complications, raises the cost of medical care, and most importantly, interferes with recovery and return to normal activities of daily living. Management of post-surgical pain is a basic patient right. When pain is controlled or removed, a patient is better able to participate in activities such as walking or eating, which will encourage his or her recovery. Patients will also sleep better, which aids the healing process.
Pain is recognized in two different forms: physiologic pain and clinical pain. Physiologic pain comes and goes, and is the result of experiencing a high-intensity sensation. It often acts as a safety mechanism to warn individuals of danger (e.g., a burn, animal scratch, or broken glass). Clinical pain, in contrast, is marked by hypersensitivity to painful stimuli around a localized site, and also is felt in non-injured areas nearby. When a patient undergoes surgery, tissues and nerve endings are traumatized, resulting in incision pain. This trauma overloads the pain receptors that send messages to the spinal cord, which becomes overstimulated. The resultant central sensitization is a type of posttraumatic stress to the spinal cord, which interprets any stimulation—painful or otherwise—as unpleasant. That is why a patient may feel pain in movement or physical touch in locations far from the surgical site.
Patients handle post-operative pain in high individualized ways. Health care professionals have observed that some patients report that they are in extreme pain after surgery, demanding large doses of pain medications while others seem to do well with much less medication. Several theories have been put forth for this discrepancy. For example, differences in body size seemed to require differing amounts of medication, but this theory did not explain differences in pain perception among patients of the same build. Emotional well-being was considered a better indicator of the ability to tolerate pain. It has been theorized that patients with stronger support systems and better attitudes actually perceive less pain than others. Some health care professionals have even speculated that extreme pain was not real in many cases, but was a way to seek attention.
Clear biological evidence proving that individuals are born with varying thresholds of pain perception was only recently discovered. Psychiatrist and radiologist Jon-Kar Zubieta, from the Mental Health Research Institute at the University of Michigan, found that variations in an amino acid in a newly discovered gene, which codes for an enzyme that accesses neurotransmitters in the brain, produce different levels of pain perception. Only three combinations produce the variation. One individual may be able to fully access and metabolize the opioid neurotransmitters that reduce the sensation of pain. This person would have a higher threshold of pain tolerance and a lower level of pain perception. Another might not be able to do so at all, and that individual would experience more intense pain from the same stimulus. A third person might be able to tolerate a moderate amount of pain.
This variation in genes not only shows that individuals do indeed experience pain at different levels, but it also points to differences in how people behave toward other stressors. Genetic variation may be a factor in the impact of long-term illness and depression that often accompanies chronic pain.
Since pain perception is highly subjective, it is important for the health care team to be aware of pain sensitivity differences in patients, and to value patient self-report as a reliable tool for pain assessment. The most common self-report system in use is the pain intensity scale. The patient is asked to identify where the pain falls on a scale of 0 "no pain at all" to 10 "the worst pain in the world." This scale, however, does have limitations. The Short-Form McGill Questionnaire, which uses sensory words or synonyms, may allow the patient to communicate more accurate, descriptive information about pain and may be a better tool in planning pain management strategies.
It is clear that there is a real need for providing different approaches to post-surgical pain management. A variety of interventions may be used before, during, and after surgery. Most of these methods involve medications given orally, intravenously, intramuscularly, or topically (via the skin). Some must be administered by a health care professional; others by the patient.
Pre-surgery pain management
The goal of post-surgical pain management is to reduce the amount pain a patient experiences after surgery. New research has suggested that preventing the nervous system from being overtaxed by pain from the trauma of surgery may lead to a less painful postoperative experience. Pretreated patients may require less post-surgical medications, and they may recover more quickly, possibly experiencing pain-free days far sooner than patients who have used traditional post-surgical pain methods.
Also, in view of improved, less-invasive surgical techniques and the insurance industry's trend after the turn of the twenty-first century to trim rising medical costs by reducing the length of hospital stays, many patients have no longer been required to remain overnight in a hospital. Recently, outpatient (also called ambulatory) surgery has become a procedure of choice for many complex surgeries, such as hysterectomy and prostatectomy. The patient must now be made comfortable enough to return home and manage his or her own pain.
Preemptive analgesia introduces anesthetic drugs near the spinal cord or, sometimes, in nerve blocks in specific regions of the body. An epidural catheter, a thin plastic tube through which pain medication is delivered, is inserted into the patient's back before surgery. The patient may also receive general anesthesia and post-surgical pain medications as needed. Sometimes, the epidural catheter remains in place for several hours or days after surgery, and is attached to a pump so the patient can administer medication on demand.
In other cases, peripheral nerve blocks are used to limit sensation in specific regions of the body. By injecting local anesthetic near a nerve or nerve plexus that supplies the area where the surgery will be performed, all sensation is blunted and the affected area is numbed and feels "asleep." Some patients remain awake, but sedated, during surgery; others are given general anesthesia. Two important advantages to the use of peripheral nerve blocks in patients who are awake during surgery is the avoidance of the side effects of general anesthesia (nausea and vomiting) and complications that could occur during intubation, placing a tube in the patient's airway. The use of peripheral nerve blocks alone may be best suited to surgical procedures involving the arms, legs, and shoulders.
Pain management during surgery
General anesthesia has been the standard for pain management during surgery. Topical local anesthetics are also being used to numb the surgical site before any incisions are made. This has been the method used frequently with laparoscopic procedures. In a laparoscopy, the surgeon inserts a laparascope (an instrument that has a tiny video camera attached) through a small incision, often in the abdomen. Other small incisions are made for the surgeon to insert surgical instruments into, and to do repairs or remove diseased or damaged tissues. Local anesthetics minimize pain trauma to the surgical site and the central nervous system.
Post-surgery pain management
In most hospitals during the past century, post-surgical pain management consisted only of the administration of analgesics and narcotics immediately after surgery. These drugs were usually given by intravenous or intramuscular injection, or by mouth. This is still a viable method for managing post-operative pain.
Management of these drugs, nevertheless, has variant applications. Some hospitals insist on a routine of scheduled medications, rather than giving medications as needed. The health care staff in these instances state that when patients take medications before the pain appears, the body does not over-react to the pain stimulus. Therefore, staying ahead of the pain is critical.
Other hospitals advocate continuous around-the-clock dosing through the use of a pump-type device that immediately delivers medication into the veins (intravenously, the most common method), under the skin (subcutaneously), or between the dura mater and the skull (epidurally). A health care provider programs the device with the specific dosage to deliver at each request made by the patient, as well as the total permitted during the time for which the device is set (commonly eight hours, sometimes 12, especially if the health care providers are working 12-hour shifts). Some of these devices are very sophisticated and even monitor themselves, ringing an alarm bell if there is an indication that they might be malfunctioning. The patient administers the dose by pushing a button, and is encouraged to keep a steady supply of medication within his or her system. This is called patient-controlled analgesia (PCA).
PCA provides pain medication at the patient's need. However, because opium-like pain-relievers (opioids) are the medications these pumps deliver, there has been some concern about possible narcotic addiction. The pumps are calibrated to a maximum dosage, and are limited to a maximum dose every eight (or 12) hours. The health care staff checks the equipment regularly, and records the number of times the patient pushes the pump button. If the patient has pushed the button more times than allowed, the pump refuses to administer more medication. The patient should notify the health care staff if a specific medication is ineffective. In some cases, the patient needs encouragement to use the pump more, if necessary.
Nonsteroid anti-inflammatory analgesics (NSAIDs) are best used for continuous around-the-clock pain relief. This prevents the extremes in pain perception that occur with on-demand dosing; sometimes the patient feels no pain and extreme pain at other times. Opioids are best given on a schedule or in a computerized pump, which can prevent overdoses.
Another method used post-surgically is the On-Q or the "pain relief ball." It is a balloon-type device that administers non-narcotic medication to the incision site through a small catheter. When the incision site is closed, the catheter is attached to the surgical site and the balloon or pump is either taped to the patient's skin, carried in a pocket or pouch, or attached to the patient's clothing. The pump numbs the incision site by flooding it with anesthetic. Recent tests show that On-Q reduces narcotic use by 40% in cesarean patients, and eliminates all narcotics in 43% of hysterectomy patients.
Alternative non-medical methods
Some non-medical methods can help reduce post-operative pain. Patient education about the surgical procedure and the aftermath can help reduce stress, which can affect the perception of pain. Education, like visualization, prepares the mind for surgery and recovery. The patient knows what to expect, thereby removing fear of the unknown. Education also enlists the patient's cooperation and may encourage a feeling of control and empowerment, which reduces stress, fear, and helplessness. These factors can contribute to less perceived pain. Therefore, both education and visualization can be helpful in minimizing pain perception and encouraging a positive attitude after surgery, which can promote healing.
Meditation and deep breathing techniques also can reduce stress. These techniques can lower blood pressure and increase oxygen levels, which are critical to a healthy recovery. Hypnosis before and after surgery may calm the mind and emotions, and mute the perception of pain.
Multimodal analgesia uses more than one method of pain management. Multiple methods can actually reduce the amount of medications necessary to relieve pain, and can minimize uncomfortable side-effects. Using pre-surgical, surgical, and post-surgical techniques allows the patient to arise from surgery with the pain already under control.
Further knowledge about multimodal pain management will be necessary as more outpatient and office-based surgery is done. Finding the right combination of methods for an individual patient will be the challenge and responsibility of the health care team.
Of great concern to health-care professionals is how to provide post-operative pain management to patients who are opioid tolerant. These patients require higher and more frequent doses of narcotics for pain relief. They may also need to stay on the narcotics longer, and gradually step back down to their pre-surgery levels.
Patients who are opioid tolerant are not necessarily illegal drug users, but may be taking medications in combination with a narcotic, such as oxycodone/acetaminophen or acetaminophen/codeine. Patients who take opioid medications regularly may be treating pain for conditions like cancer, fibromyalgia, arthritis, or traumatic physical injuries.
It is important for anesthesiologists to aggressively treat pain for opioid-tolerant patients in the recovery room, where they can be closely monitored. Patient-controlled pain administration or continuous infusion, either in an IV or in an epidural catheter, has the best chance of controlling post-surgical pain together with the pain caused by preexisting conditions. When the patient is able to take medications orally, NSAIDs can supplement the use of opioid analgesia, sometimes reducing the total amount of opioids used. Newer, COX-2 inhibitors have proven effective in reducing pain without many of the side effects that NSAIDs possess (liver complications, kidney impairment, intestinal tract irritation, and bleeding), and seem to be a good fit for the opioid-tolerant patient.
Before having any surgery, the patient should talk with the physician, surgeon, and if possible, the anesthesiologist in order to gain a full understanding of the procedure and what to expect immediately following surgery. It is important to develop a pain management plan with the health care team, and for the patient to be open about medication use, including opioids. Usually the patient will meet the anesthesiologist the day of the surgery to discuss pain management options for the operation. Being informed about the surgical procedure and anesthesia options will give the patient an opportunity to ask questions and respond accurately to those asked by the anesthesiologist.
The physician should take a complete medical history, and order tests to determine the patient's current liver and kidney functions. Surgical patients should communicate their pain medication needs to the health care team.
The patient should not eat or drink before surgery. This helps minimize the side effects of general anesthesia and pain medications, such as nausea and vomiting. If the patient cannot reach a comfort level with the prescribed medication regime, he or she should discuss this with the health-care staff and physician.
After surgery, a patient should not have to endure severe pain. A reasonable comfort level can be reached in most cases. Prudent pain management will allow the patient to eat, sleep, move, and begin doing normal activities even while in the hospital, and especially when returning home. Recovery may take several weeks after surgery; however, the patient should be made comfortable with a regime of oral pain medications.
Pain medications may have unpleasant side effects. In many people, narcotics cause nausea, vomiting, and impaired mental functioning. NSAIDs can cause kidney failure, intestinal bleeding, and liver dysfunction, but this is not true for everyone. The NSAID ketorolac has been associated with acute renal (kidney) failure even when given for minor oral surgery in an outpatient setting. Early screening for kidney problems and close monitoring for kidney failure or dehydration can prevent most of these problems.
There are adequate safeguards in place, especially in patient-controlled analgesic pumps, to prevent addiction to narcotics; however, some patients do become addicted. In these cases, there usually is an underlying predisposition toward physical addiction that had not previously appeared.
See also Pain management.
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American Association of Nurse Anesthetists (AANA). 222 S. Prospect Ave., Park Ridge, IL 60068-4001. (847) 692-7050. <www.aana.com>.
Association of Perioperative Registered Nurses (AORN). 2170 S. Parker Rd., Suite 300, Denver, CO 80231. (800) 755-2676 or (303) 755-6304. <www.aorn.org>.