Managing Pain in Intensive Care Units
Inadequately relieved pain is often described after intensive care unit (ICU) hospitalization. Pulmonary dysfunction, cardiac dysfunction, and difficulty weaning from mechanical ventilation are potential consequences caused by ongoing pain. Managing pain in ICUs may seem daunting due to the patients’ serious and often unstable health status, healthcare providers’ lack of awareness regarding pain’s impact on overall health status, coupled with the physical care demands within the critical care environment. Factors contributing to the overall under-treatment of pain in ICUs include pain assessment challenges for nonverbal patients, staff and family concerns about the consequences of using analgesic medications, and prioritization of complex medical needs. To mitigate these obstacles while providing optimal pain control, proper identification of underlying pain symptoms through the use of behavioral assessment tools and continual monitoring of physiologic markers should occur. Patients and professional caregivers must become more knowledgeable about the necessity of simultaneously managing pain and stabilizing underlying medical conditions. The desired goal for patients receiving care in ICUs should be their medical recovery and transfer out of the ICU and, if this is not possible, relief of their pain and discomfort during the withdrawal of life sustaining treatment or when their death is imminent.
Patients in ICUs vary in their range of pathologies and ages. Patients between the ages 60 to 69 years account for most of ICU admissions.1 Two large cohort studies show that the most common pathologies treated in ICUs are (in descending order): postoperative complications, acute lung disease with and with out multi-organ failure, chronic lung disease, and neurologic disorders. Importantly, five to ten percent of adult ICU patients are chronically and critically ill, as defined by receiving mechanical ventilation for at least 21 days or requiring tracheostomy.2
Depending upon geographic area, patients in ICUs also vary in terms of their ethnicity, culture, level of education, and social background. These factors have relevance when addressing pain. Members of some cultural and ethnic groups may have underlying beliefs and understandings about pain and its treatment. Some groups interpret pain as a part of the healing process and neglect to inform their health care providers about pain’s presence. Others interpret pain reporting as a sign of weakness and so may also neglect to report its occurrence. Some tend to overestimate their pain intensity and significance.3 Because there are so many contributing variables to the experience of an individual’s understanding about pain, it is difficult to make broad, general assumptions based solely upon culture, ethnicity, education, or socio-economic class. It is more important clinically for healthcare providers to be sensitive to, and respectful of, cultural, educational, ethnic and other variations when assessing and treating each patient’s pain.
“Ideally, pain assessments should include location, characteristics, severity, onset, progression, duration, quality, radiation, alleviating and exacerbating factors, and effects of previous therapies.”
Need for Pain Treatment in the ICU Patients in the ICU are often in need of pain medicine for a myriad of reasons, including weaning off ventilatory support, pulmonary dysfunction, and cardiac dysfunction.
Prolonged Mechanical Ventilation. People receiving ICU care should be weaned from mechanical ventilation as soon as possible to prevent complications such as barotrauma, atelectasis, and infection. Mechanical ventilation also indirectly leads to other medical complications such as pressure ulcers, gastric ulcers, muscular weakness, and renal failure. Inappropriately managed pain may inhibit weaning from ventilatory support.4
Pulmonary Dysfunction. This may also result from inadequate pain control in postoperative patients—particularly following upper abdominal and thoracic surgeries—and for those with abdominal pathology such as pancreatitis.2 Sustained abdominal muscle contractions caused by unrelieved pain result in decreased lung volumes, decreased functional residual capacity (FRC), and decreased functional vital capacity (FVC). The cough reflex is compromised with reduced FRC and FVC, leading to retained pulmonary secretions and the potential for pneumonia. Pain may also induce vasoconstriction which, when coupled with venous stasis from immobility, may ultimately lead to thrombus formation and fatal pulmonary embolism.5
Cardiac Dysfunction. Treatment of pain for patients with myocardial infarction (MI) or acute coronary syndrome is critically important. It has been recommended that morphine or other opioid analgesics should be administered for chest pain refractory to nitroglycerin. It is theorized that morphine reduces oxygen consumption by decreasing sympathetic activity and increases blood delivery through its vasodilatory affects.6 In contrast, the administration of NSAIDs counteracts the effects of angiotensin converting enzyme inhibitor (ACEI) and diuretics, thereby increasing the incidence of congestive heart failure (CHF) and MI.7,8 It is necessary to not only treat the underlying cause of chest pain, but to use the proper type of analgesics.
Assessment Of Pain
A thorough pain assessment is essential regardless of the clinical setting. Ideally, pain assessments should include location, characteristics, severity, onset, progression, duration, quality, radiation, alleviating and exacerbating factors, and effects of previous therapies. This information guides clinicians toward the underlying cause for pain, as well as determines which therapeutic interventions will be utilized.
Choosing the Proper Assessment Tool. Assessment of pain severity serves to gauge the effectiveness of therapeutic interventions. Pain severity is determined through assessment tools used by healthcare providers, surrogates, or directly by patients. Patients’ self reports about their pain are considered to be the most accurate.9
Since patients in ICUs are commonly unable to work with typical pain assessment scales requiring them to give a verbal response, the Behavioral Pain Scale (BPS) is considered to be an alternative tool for assessing pain in critically ill, sedated, and mechanically ventilated patients. The BPS assesses pain through evaluation of facial expression, upper limb movements, and compliance with mechanical ventilation.
During a six-month prospective validation study, Aissaoui et al performed 360 observations of 30 patients in ICUs. They measured BPS and two physiologic markers—arterial blood pressure and heart rate—at rest and during two painful procedures, tracheal suctioning and peripheral venous cannulation; at three different times of the day. Significant increases in BPS scores occurred between rest and the two painful procedures. There was an indirect correlation between the degree of sedation and BPS. They showed that the BPS was a valid pain assessment tool for critically ill patients.10