IASP Post-Surgical Pain Fact Sheets

Almost half of postsurgical inpatients surveyed in the latter part of the 20th century reported episodes of severe postsurgical pain. This Fact Sheet addresses what the patient and their family should do to prepare for an upcoming surgery to help ensure their pain is effectively managed. This includes, discussing the likelihood of pain, as well as its likely intensity, duration, and plan to manage it. The patient is asked to reveal relevant aspects of their medical history such as prior pain problems, current pain therapies, and conditions such as adverse reactions to medications. The patient is encouraged to ask who will formulate the personal “pain plan”, if it will be “multimodal”, who will monitor the pain plan and adjust or change it if needed and what are the plans for pain control after discharge from the hospital – including who to contact if the pain plan is inadequate. Overall, this guidance encourages patient and family-centered care based upon evidence and shared decision-making.

Some points discussed in this Fact Sheet include the fact that nearly all pain after surgery can be managed to optimize physical and emotional function. It reminds healthcare providers that they have the responsibility to provide patients with the best pain control possible, which does not mean all patients must have “zero pain”. Rather, it means that for each patient the risks, benefits, and ability to safely provide postoperative care must include effective pain control as an integral component. To best achieve this, a patient-centered multimodal strategy  for pre-, intra-, and postoperative pain control, that is integrated with other dimensions of enhanced recovery, must be employed. Clinical guidelines must be adjusted and personalized according to individual patient variability and needs. Evidence-guided, procedure- and site-specific approaches to pain management can reduce or avoid unfavorable patient experiences, undesired clinical outcomes, and costly administrative burdens.

This Fact Sheet discusses the neuro-physiology of tissue trauma from initial nociceptor activation to sensitization. It points out the variety of patterns of nociceptor sensitization with differences in the quality, location, and intensity of postoperative pain. Local and systemic mediators released during and after surgery contribute to nociceptor sensitization and may persist at the surgical site for several days. These responses may contribute to peripheral sensitization and spontaneous pain behavior following an incision. Nerves injured during surgery will discharge spontaneously and may account for qualitative features of neuropathic pain that may be present early in the postoperative period and can evolve into chronic pain. Furthermore, noxious input during and after surgery can enhance the responses of nociceptive neurons in the CNS, resulting in central sensitization, thereby amplifying pain intensity.

Chronic Postsurgical Pain (CPSP) is considered pain that persists at least three months after surgery and can continue to be present for one year or more. The exact incidence and severity of CPSP is difficult to determine, for various reasons; but, overall, CPSP occurs in roughly one or two of every 10 surgical patients and is intolerable after roughly one or two of every 100 operations. The type of surgical procedure influences both the incidence and severity of CPSP. Laparoscopic procedures and minimally invasive approaches, unfortunately, have shown little benefit on the development of CPSP. Being able to predict which patients are at high risk for CPSP might, in theory, allow preemptive targeted therapy.  Unfortunately again, the predictive “tools” lack perfect specificity and sensitivity and so are best viewed as broad guides. Some potential factors that appear to put patients at risk include emotional overload, preoperative pain at the operative site, other chronic preoperative pain, acute postoperative pain, and co-morbid stress symptoms such as anxiety. Postoperative pain is consistently shown to be an important determinant of the development of CPSP, particularly the duration of severe pain after surgery. A final “unfortunately” is that, to date, attempts at prevention of CPSP have been less than would be hoped. For example, regional anesthesia may reduce the risk of CPSP in some patients, ketamine infused perioperatively has produced some positive findings and gabapentinoids, in aggregate, lack a significant effect.

One of the major points discussed in this Sheet is the fact that the “old” way of controlling postoperative pain by relying solely on opioids has evolved into the “new” multimodal approach that includes non-opioid medications and techniques to improve effectiveness and reduce side effects. Certainly opioids remain an important piece in managing severe postsurgical pain, but their use as the sole agent can cause significant morbidity. Evidence suggests that the use of two or more analgesic medications or techniques with different sites or mechanisms of action provides the best analgesia, reduces the amount of opioids needed and reduces the side-effects from opioids. The issue that remains is the need for further research to identify which specific combinations of agents and techniques are most suitable for individual patients in each operative and postoperative setting. Another point is that good postsurgical analgesia by itself is likely not enough to improve postoperative outcome and recovery. However, the achievement of good pain control allows the protocols for enhanced recovery after surgery, that address multiple dimensions of recovery, to facilitate shortened hospital stays and reduce rates of complications.

The most important thing to take from this Fact Sheet is to remember that there is an important distinction between pain and nociception. Pain is a subjective, multidimensional experience unique to the individual which has sensory, emotional, and cognitive aspects. Because of this there is a wide spectrum of patient attributes, both positive and negative, that influence the experience of acute pain after surgery. Some of these attributes are traits, but they can also be states that patients achieve over time. Thus, behavioral modalities can be effective in decreasing acute postsurgical pain and other symptoms such as anxiety. In addition, certain patient-related psychosocial factors can put people at risk for the development of chronic postsurgical pain. As of now, there have been few well-designed outcome studies of psychological treatments that specifically target preoperative risk factors aimed at preventing or reducing CPSP. However, certain cognitive-behavioral or mind-body interventions may hold promise.

Children often cannot advocate for themselves, and may not complain of pain, so they need special attention and pain assessment using age-appropriate validated tools. All health professionals who treat children should know how to recognize, assess, and manage pain. Untreated acute pain can result in chronic pain in children and adolescents, and failure to prevent pain in newborns can cause lifelong adverse effects, such as increased pain sensitivity. Most medications are safe in children and infants, if the dosing is adjusted appropriately. Psychological and physical techniques are very important as is the parents’ role in providing distraction, support, and comfort.

Unfortunately, pain after surgery in older adults is often not recognized or properly treated. In addition, it is important to realize that inadequate pain control may lead to negative functional, cognitive, and/or emotional consequences. This Fact Sheet discusses preoperative evaluation, postoperative assessment and perioperative treatment options with a focus on the older adult, however, most of what is discussed is relevant to caring for patients of all ages. In terms of preoperative evaluation of the older adult it is important to assess baseline chronological age and biological age, mental status, functional status, and cognitive function, including memory. The review of systems, as usual, should identify any impairment of the respiratory, cardiac, hepatic, endocrine, and renal systems as they can alter pharmacokinetics and pharmacodynamics of analgesics. There are a number of options available to assess postoperative pain in the older patient if they are not able to adequately utilize the self-reported numeric pain scale (i.e., 0 to 10). Two of the most common options are to use a verbal descriptive scale (e.g., none, mild, moderate, severe) or the FACES Pain Scale. There is also the PAINAD which is meant for use in the adult patient with advanced dementia who is unable to self report pain level. A final option is to use the Functional Pain Scale (FPS) which incorporates both subjective and objective components to assess pain, based on the pain’s perceived tolerability and interference with functioning. The FPS may be superior to other approaches if visual or mild-moderate cognitive impairments are present. As for postoperative pain management in general, an individualized approach tailored to the older patient and context that employs both nonpharmacological and pharmacological modalities whenever possible is optimal. The concept of “start low and go slow” (when increasing dose or frequency) is important in the older patient, but do not under-treat either.

Increasing numbers of patients are presenting for surgery who are on opioids preoperatively for a variety of reasons (e.g., cancer-related pain, chronic non-cancer pain, recurrent acute pain, opioid maintenance treated substance use disorder, and illicit opioid use). With careful planning, and a little extra thought, this patient population can be effectively cared for just like any other. One thing that is important to remember is that these patients are tolerant to the analgesic effects of opioids. Recall that tolerance refers to the decrease in the effect of a drug administered repeatedly over time—or the need for increasing doses over time to evoke the same response as the initial dose. Because of this, opioid-tolerant patients are at increased risk of acute and chronic postsurgical pain and of under-treatment of pain.

Major principles for postoperative pain management in opioid-tolerant patients are:

◊ Careful perioperative assessment, including psychosocial factors
◊ Providing effective analgesia despite reduced effects of opioids (note: opioids can still be used, however, opioid dosing must be titrated to effect, and their analgesic effect may be limited, thus multimodal analgesia is particularly useful)
◊ Attenuation of tolerance and opioid-induced hyperalgesia (i.e., increased sensitivity to nociceptive stimuli)
◊ Prevention of opioid abstinence syndrome (long-term use of opioids induces physical dependence, which creates a risk of withdrawal if they are abruptly reduced or stopped)
◊ Close communication between all health-care professionals involved in the patients’ in-house care
◊ Appropriate discharge planning, including coordination with the healthcare professionals who follow the patients in the outpatient setting
◊ Use of the lowest likely dose of postoperative opioids (allowing for the presence of analgesic tolerance) for the shortest necessary duration after discharge

With continued advances in cancer therapy, patients are surviving with indolent disease or in remission; with many experiencing pain related to the disease or as a sequelae of radiation and/or chemotherapy (e.g., neuropathic pain). “Optimal postoperative pain management for cancer patients requires individualized assessment and planning”, as it does for all patients. In the pre-operative period it is important to determine if the known or suspected malignancy has any clinical features of potential relevance to the pain plan (e.g., altered mental status, hepatic or renal insufficiency) and if prior treatment of the malignancy or its associated pain influences the pain plan (e.g., is the patient opioid tolerant). Postoperatively, pain and its management will depend on the type of cancer, the type and technique of surgery, any adjuvant therapy the patient received and the presence of chronic pain. Adequate opioid doses will need to be used in patients on them preop, development of persistent postsurgical pain will need to be watched for and assessment of psychological states (and management thereof) will need to be undertaken.

As the Fact Sheet states, for years, mortality was the sole outcome of importance for critical care patients. Recently, patient-centered outcomes, including pain, have become increasingly important. Per the literature, slightly more than 50% of ICU patients report acute pain of moderate to severe intensity at rest, leading to physical and psychological distress as well as sleep disturbances. Assessment of pain in all patients in the ICU (including using appropriate tools for those who are intubated and sedated) is necessary and beneficial. Management of sedation and analgesia with established protocols is associated with better outcomes. As with all patients, the use of multimodal analgesia techniques is recommended in ICU patients to reduce the reliance on opioids. There is less information available for patients following a SICU admission, but the problem of chronic postsurgical pain likely exists for them as well. For example, one study showed that 57% of patients discharged from a SICU report pain and discomfort at six years and later. Another study, in a mixed medical-surgical ICU, showed that 16% of patients experienced chronic ICU-related pain at six months after discharge.

The use of non-pharmacologic modalities for postoperative pain relief is recommended, although several of the options have limited evidence of benefit. One – acupuncture – holds promise in providing analgesia, as well as diminishing the side effects associated with pharmacologic agents. Electro-acupuncture at low- and medium-frequency stimulation release of endogenous opioids, whereas at high-frequency stimulation it may cause norepinephrine and serotonin release. A systematic review comparing acupuncture versus sham in various surgeries showed that postoperative pain was reduced in the acupuncture groups at 8 and 72 hours post-surgery. A significant difference was also found in mean opioid consumption at 8, 24, and 72 hours, with the greatest cumulative benefit seen if acupuncture was administered prior to the operation. Another systematic review found that the addition of acupuncture or acupressure reduced the incidence of postoperative nausea and vomiting compared with antiemetic prophylaxis alone. Finally, a meta-analysis found that compared with placebo and medication control groups, all acupoint stimulations (i.e., acupuncture, acupressure, or electrical stimulation) significantly reduced nausea, vomiting, and the use of rescue anti-emetics.

This Fact Sheet states that chronic postsurgical pain (CPSP) is common, with an overall incidence of up to 50 percent (or more) of postsurgical patients, and is severe and disabling in 2 to 10 percent of patients. The etiology of CPSP is still not completely understood, but some risk factors (depending on the type of surgery) appear to be preoperative pain, young age, genetic susceptibility, psychological issues, cognitive factors, surgical nerve injury, and the severity of postoperative pain. Patients presenting with suspected CPSP should undergo an assessment to “confirm” the diagnosis and most importantly identify the underlying mechanisms of pain. In addition, it is important to assess their physical and emotional functioning and any quality of life issues. CPSP can be a combination of different clinical types of pain, such as neuropathic, nociceptive, or visceral – with neuropathic being the most common. It is important to differentiate the generator of the pain in order to choose the proper treatment modality, with a multimodal approach (as always) being the best option. As with other chronic pain syndromes, once CPSP is established it is challenging to reverse, thus prevention remains the key. Therefore, intensive postoperative follow up and early management at the first signs of new or recurrent pain is critical.

As with all outcomes in healthcare, pain outcomes need to be evaluated in order to make treatment decisions at point-of-care for individual patients, as well as for quality improvement initiatives. Unfortunately, there is no consensus as to what constitutes “high-quality” perioperative pain management. It is unclear what the desired outcomes are, let alone how and when to measure them, thus presently making it difficult to judge quality. Outcomes of importance related to pain management differ based on the perspective of the observer (i.e., the patient, a clinician, an administrator, or a researcher). Providers usually focus on clinical outcomes such as pain intensity, analgesic consumption or complications. In general, it is assumed that the patient is most concerned about pain intensity, however this is often not the case if one actually asks the patient. In addition to intensity, other patient-reported outcomes that are equally or more important to patients are interference with function, adverse effects, quality of life, or quality of recovery. Of course, health economic outcomes cannot be ignored and include costs of resource utilization and interventions versus any realized cost savings from improved pain management (e.g., decreased LOS, reduced incidence of CPSP). To help guide treatment for an individual patient, several outcomes should be used together to assess the patient’s “pain status”. The overarching goal is usually early functional recovery and the outcome targets should, when possible, include no worse than mild pain and minimal interference with function from pain and pain treatments. The dynamic nature of postoperative pain requires repeated measurements over time. Basing treatment decisions on single ratings of pain intensity has not been shown to be associated with improved care and, in fact, has been linked to reports of over-treatment and serious adverse events. It is presumed that, instead, we should be basing treatment on the pain trajectory (i.e., pain intensity scores over time), however there is limited knowledge of how best to do so. Having a clinical data registry can provide information needed for quality improvement initiatives. For example, providers can use the data to track their own performance and the effect of interventions, thereby identifying areas for improvement, and hospitals can use the data to compare performance with other institutions. Pain performance indicators for inpatients are publicly reported through the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey (note: the questions changed in 2018 to ask if healthcare providers talked with the patient about pain, as opposed to how well the pain was controlled). Health systems should also consider it important to monitor pain management performance after discharge; because, as hospital stays become shorter, pain problems after surgery (e.g., chronic postsurgical pain) may go unrecognized in the community.