Assessment and Management of Pain in Critically Ill Patients

Abstract

P ain in intensive care units is often underestimated, and therefore patients are insufficiently treated, leading to psychological, hemodynamic, metabolic and responses that cause greater morbidity and mortality. Pain sensation begins in the periphery of the nervous system. Recent tissue damage due to illness, injury, or surgery initiates the release of local inflammatory mediators which in turn stimulate specialized nociceptors that are the nerve terminals of the primary afferent fibers. The pain signal is then transmitted to the dorsal horn of the spinal column and transmitted through the central nervous system (CNS) where it is processed and interpreted in the somatosensory cerebral cortex. An effective analgesic protocol involves detecting, treating, and reassessing pain. Effective assessment and treatment of pain can reduce the need for sedative-hypnotics, decrease duration of mechanical ventilation, shorten ICU and hospital length of stay, and reduce mortality. In patients who can communicate; the gold standard for assessing pain is patient self-reporting, and this approach should be utilized whenever possible. Although many self-reporting pain intensity scales are available, it has been shown that the 0 to 10 Numeric Rating Scale is the most feasible and discriminative self-report scale for assessement of pain intensity incritically ill patients. However, many ICU patients may be unable to provide their self-report due to a variety of factors, including an disturbed conscious level, the use of high doses of sedative or hypnotic agents, and mechanical ventilation. In such situations, the use of behavioral pain scales is highly recommended because it is considered as the alternative measure for assessing pain when the self-report is impossible to obtain. The BPS and CPOT are the most validated and reliable behavioural scales for monitoring pain in adult patients when self-reporting is not possible (except brain damage), whenever motor function is intact and their behaviour can be observed. Although vital signs are easily accessible through continuous monitoring in the ICU, they have been shown to have low specificity for pain and not to correlate with patients' self-reports of pain or validated behavioral pain scores. Therefore, their use as the sole method for determining the need for analgesic administration in ICU patients is strongly discouraged. Opioids such as fentanyl, morphine, and hydromorphone remain the treatment of choice for managing acute nonneuropathic pain in ICU patients. Their proven efficacy, familiarity to clinicians and multiple routes of administration all contribute to their effectivenessss.