Postoperative Pain Control

Anatomy and Physiology

Afferent neural pathways mediate pain sensation.[6] Acute postsurgical pain can be categorized as nociceptive, inflammatory, or neuropathic. Nociceptive pain is mediated by activated unmyelinated C-fibers, thinly myelinated A-delta-fibers, and myelinated A-beta-fibers. Usually, this type of pain occurs in response to noxious stimuli such as direct intraoperative tissue injury (eg, making a skin incision). Inflammatory pain occurs when nociceptive fibers become sensitized in response to releasing inflammatory mediators such as cytokines. The clinical manifestation of inflammatory pain may comprise the 4 classic signs of inflammation (pain, heat, erythema, and swelling). Inflammatory pain may last hours to days in duration and is generally reversible. Neuropathic pain results from injury to neuronal structures (eg, peripheral nerves), whereby pain occurs due to increased axonal sensitivity to stimuli. Neuropathic pain will present in the immediate postoperative period and may persist as chronic postoperative pain.[7]

Postoperative pain can additionally be characterized as somatic or visceral. The somatic division of pain is composed of a rich input of nociceptive myelinated, rapidly conducting A-beta-fibers found in cutaneous and deep tissue, which contribute to a more localized, sharp quality.[3][7] The visceral division of pain comprises a network of unmyelinated C-fibers and thinly myelinated A-delta-fibers that span multiple viscera and converge together before entering the spinal cord. Also, visceral afferent fibers run close to the autonomic ganglia before their entrance into the dorsal root of the spinal cord. These characteristic features of visceral nociceptive fibers contribute to a more diffuse, poorly localized pattern of pain that may be accompanied by autonomic reactions such as a change in heart rate or blood pressure.[7] Therapeutic interventions developed for pain management target the afferent pain pathway by various mechanisms. For example, antagonizing pain receptor activity or blocking pro-inflammatory mediators production.[6][8]

Indications

Postoperative pain management tailored individually to a patient’s comorbidities and social factors is associated with reduced postoperative opioid consumption, reduced length of hospital admission, decreased preoperative anxiety, and fewer sedative medication requests.[2]

Contraindications

Pharmacological agents used in mediating postoperative pain control are contraindicated if the patient has a history of allergic reactions associated with their use. Due to an increased risk of cardiovascular events, nonsteroidal anti-inflammatory drugs are contraindicated in patients who have undergone coronary artery bypass grafting.[2]

Equipment

Equipment used in techniques that involve the delivery of interventional postoperative pain relief:

• Peripheral intravenous (IV) access
• Sterile skin preparation
• Sterile field
• Vital sign monitoring: pulse oximetry, telemetry, and noninvasive blood pressure monitoring
• Resuscitation equipment: oxygen supply, airway supplies, suction, resuscitative medications, and defibrillator
• Ultrasound machine
• Anesthetic medication
• Hollow needles: gauge, shape, and length vary according to the type of anesthesia performed (eg, beveled needles, spinal needles)
• Catheter assembly
• Peripheral nerve stimulator

Equipment used to set up patient-controlled analgesia pumps:

• Peripheral IV access
• Patient-controlled analgesia pump device
• IV tubing primed with saline
• Carbon dioxide detector cannula
• Narcotic medication

Tools for evaluation of adequate pain control in acute pain:

• Visual analog scales 
• Heft-Parker visual analog scale 
• Verbal rating scale 
• Numerical rating scale 
• Faces pain scale 
• Wong-Baker faces pain rating scale 

Personnel

An interprofessional team approach should be used to tailor an individualized pain management plan for the postoperative patient. The team should include the patient’s primary care provider, a pharmacist, the surgeon, the anesthesiologist, the operating room staff, and the nursing staff involved in the case. Depending on the patient’s history and the nature of the procedure, a pain management specialist, physical therapist, or psychiatrist may also be included in the patient’s pain management plan.

Recently, numerous facilities have introduced acute pain service groups and enhanced recovery after surgery programs to establish pain score monitoring protocols and enhance intervention strategies for better postoperative pain management in surgical wards. Theoretically, the parameters set by these programs would allow ward nurses to play a more active role in monitoring and managing postoperative pain, allowing for increasingly adequate pain control.[5]

Preparation

Complete a thorough patient history and physical preoperatively to assess individual factors that may impact postoperative pain severity and the selection of treatment modalities used in the patient’s pain management plan. Factors to consider when developing a postoperative pain management strategy include the type of procedure anticipated, patient age, history of chronic opioid use, and other comorbidities.[6][9]

Comorbid Conditions

Obesity presents a challenge in opioid administration as this population is more susceptible to respiratory depression or sleep apnea. Regional anesthetic techniques and avoiding sedative analgesics are preferred analgesic approaches among this population.[10] Patients with chronic pain who rely on opioid treatment for relief will require opioids that exceed their baseline dose. Emphasis on multimodal therapy involving interventional anesthetic techniques and nonopioid analgesics is significant among this population.[10]

Considering the recent opioid epidemic, evaluating patients for risk factors that may predispose a patient to opioid misuse is also an essential component of the preoperative exam. Evidence suggests that patients who are female, adolescent, or 50+ years are at increased risk of persistent opioid use. A patient with a history of depression or illicit drug, alcohol, antidepressant, or benzodiazepine use is also at increased risk of persistent opioid use.[6]

Technique or Treatment

Many preoperative, intraoperative, and postoperative interventions and management strategies are available and continue evolving to reduce and manage postoperative pain.[11] The American Society of Anesthesiologists published a practice guideline for acute pain management in the perioperative setting in 2012 that was reviewed and approved by the American Society of Regional Anesthesia and Pain Medicine.[2][12][13]

Below is a list of multimodal treatments for postsurgical pain:

• Systemic pharmacologic therapy
• Local, intra-articular, or topical techniques
• Regional anesthetic techniques
• Neuraxial anesthetic techniques
• Nonpharmacologic therapies (eg, cognitive modalities, physical therapy, transcutaneous electrical nerve stimulation)

Systemic pharmacologic therapy: Commonly used medications for postoperative pain control include opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, steroids, gabapentin or pregabalin, IV ketamine, and IV lidocaine. Intramuscular medications are discouraged. Oral administration of opioid medication is preferable over the intravenous route. However, during circumstances in which a parenteral route of medication administration is needed (eg, risk of aspiration, ileus), intravenous patient-controlled analgesia (PCA) is recommended. With PCA analgesia, avoid a basal infusion of opioid medication in opioid-naïve patients. Adding acetaminophen or NSAIDs is associated with reduced opioid consumption and better pain control than using opioids alone. Gabapentin or pregabalin are recommended for administration preoperatively, especially in opioid-tolerant patients, as they have been shown to reduce opioid requirements. Due to its extensive side effect profile, ketamine is only for major surgeries in highly opioid-tolerant or opioid-intolerant patients. Intraoperative IV lidocaine infusions have associations with a shorter duration of ileus and better analgesic control compared to placebo.[2][14]

Local, intra-articular, or topical techniques: For targeted pain control, diverse methods, including peripheral nerve blocks, intra-articular anesthetic injections, anesthetic wound infiltration, and topical anesthetics, can be employed. Although these methods are not commonly used, their administration should be based on beneficial evidence.[2]

Regional anesthetic techniques: A local anesthetic with or without the addition of IV opioid medication is an option for a fascial plane block, site-specific regional anesthetic injections, or, in some cases, epidural injections, depending on the type of procedure performed. An anesthesiologist typically performs these techniques under ultrasound guidance. Continuous IV medication (in drip form) is preferable to single-injection techniques in cases where postoperative pain is prolonged. Intrapleural analgesia is not recommended for pain control as there is little evidence to suggest benefits, and high systemic absorption within the pleural space increases the risk of drug toxicity.[2][15][16][17]

Neuraxial anesthetic techniques: This typically involves an epidural injection with local anesthetic with or without the addition of IV opioid medication; this may also include the intrathecal (spinal) injection of opioid medicines. Epidural analgesia may be given as a continuous infusion or as patient-controlled analgesia. These techniques are routinely used in major thoracic and abdominal procedures, cesarean sections, and hip or lower extremity surgeries. They are especially beneficial in patients at risk for cardiac or pulmonary complications or prolonged ileus.[2]

Nonpharmacologic therapies: Nonpharmacologic therapies used in pain control include cognitive and mechanical modalities such as transcutaneous electrical nerve stimulation.[2]

Evaluation of Adequate Pain Control

The assessment of pain severity can be accomplished by using a pain scale. Acute pain, such as that experienced in the postoperative period, is most commonly measured using unidimensional pain scales. While many different pain scales are available, the visual analog scale is the most frequently used scale to evaluate postoperative pain. This scale uses a metered line marked from 0 to 10 with word descriptions of pain at either extreme of the scale, where 0 represents “no pain” and 10 represents the “worst possible pain.”[18]

Complications

Inadequate acute pain management has numerous adverse effects on patient health, including but not limited to reduced ability to perform activities of daily living, impaired ability to sleep, low mood, and decreased libido. Not only does poor acute pain management negatively affect patient health, but it may also increase the risk of developing chronic pain.[19]

Using opioid medication may result in somnolence, sedation, respiratory depression, urinary retention, nausea/vomiting, ileus, or pruritis.[19] An opioid overdose may result in death or disability.[6] The use of opioid medication may place a patient at increased risk of addiction and substance use disorder. Early symptoms of opioid withdrawal include anxiety, restlessness, lacrimation, runny nose, diaphoresis, insomnia, frequent yawning, and muscle aches. Late symptoms of opioid withdrawal may be more intense and include diarrhea, abdominal cramping, piloerection, nausea and vomiting, tachycardia, hypertension, pupillary dilation, and blurry vision.[6] Gabapentin or pregabalin may cause symptoms of dizziness or sedation.[2]

The bleeding risk associated with using NSAIDs should be considered among patients at increased risk of blood loss, such as those who had surgery on highly vascular structures (eg, tonsillectomy) versus those that did not (eg, cholecystectomy), when developing an appropriate pain management strategy.[1] NSAIDs also correlate with an increased risk of gastrointestinal bleeding and renal dysfunction.[2]

Using peripheral regional analgesic techniques may result in a transient motor blockade, increasing the risk of falls.[2] When administering neuraxial analgesia, patients require close monitoring as respiratory depression, hypotension, and motor weakness from spinal cord compression (due to hematoma or infection) may occur.[2] Continuous intra-articular bupivacaine administration in shoulder surgery patients may increase the risk of chondrolysis.[2]

Clinical Significance

Inadequate postoperative pain control may result in adverse physiologic effects in the acute postoperative setting and increase the likelihood of developing a chronic pain syndrome.[20] A patient’s health and well-being may further decline due to chronic pain. Understanding the pathophysiology of pain, pain reduction strategies, level of invasiveness of the procedures performed, individual patient comorbidities, and social factors can help clinicians develop an optimal pain management plan that reduces the risk of poor outcomes.[4][21] Moreover, optimized postoperative pain control has been shown to reduce patient suffering, reduce hospital length of stay, aid in earlier mobilization and ability to perform activities of daily living, and improve patient satisfaction.[6][22]

Although opioid analgesic therapy remains a crucial aspect of postoperative pain management, the increase in opioid overdose-related injuries and fatalities among the general public necessitates a careful evaluation of a patient’s potential susceptibility to substance use disorder or medication misuse before prescribing and administering opioid therapy.[23] Also, patients should receive information on safe storage practices and proper medication disposal methods upon discharge home.[1] A multimodal approach and individualized plan for managing postoperative pain should be emphasized to help reduce opioid demand while optimizing pain relief.

Enhancing Healthcare Team Outcomes

Postoperative pain control is a complex endeavor requiring interprofessional participation that begins in the preoperative setting and continues into patient recovery. A thorough preoperative patient assessment by the primary care provider, nurse, surgeon, and anesthesiologist can aid in identifying patient risk factors and comorbidities that may influence the severity of their postoperative recovery period and allow for developing an individually tailored pain regimen. A multimodal, interprofessional approach to pain control allows for safer, more efficacious pain relief for the patient postoperatively as opposed to primary reliance on opioid therapy. In the immediate postoperative period, nurses play an essential role in monitoring the severity of the patient’s pain level and communicating the need for further intervention to other team members as necessary.

Clinical pharmacists are integral in deciding the least effective dose of pain medication for patients postoperatively. They can also recommend alternative medications and relay knowledge about adverse effects and interactions of any medications the patient may be taking; this helps patients make well-informed decisions about their postoperative care. The nurse, the provider, and the pharmacist all play a crucial role in educating patients and their families about postoperative pain control. They should also provide patients with well-written information about pain control postoperatively. This interprofessional approach will drive better outcomes for postoperative pain control and increase patients’ quality of life. 

Nursing, Allied Health, and Interprofessional Team Interventions

The nurse has an integral role in managing patients who encounter postoperative pain. Educating patients about their pain and administering their medications appropriately, with the correct timing and dosage, is a core competency that all nurses should practice carefully. The nurse should assist the provider in titrating doses of pain medications according to the dynamic changes in the patient’s pain scores. The nurse should alert the provider whenever there are any untoward changes in the patient’s vital signs.

Nursing, Allied Health, and Interprofessional Team Monitoring

Interprofessional team monitoring should include:

• Vital signs
• Validated visual analog scores
• Any untoward changes in the patient's condition
• The patient's level of activity and ambulation