Chapter 53: Regional Analgesia in the Critically Ill

INTRODUCTION

Intensive care specialists play increasingly greater role in the prevention and treatment of physiologic and psychological stress in critically ill patients^1,2,3 in order to prevent detrimental consequences ranging from systemic inflammatory response syndrome,⁴ to cardiac complications,^5,6 to posttraumatic stress disorder.^7,8,9 Studies have addressed the questions of an optimal sedation regimen, and several evidence-based guidelines and strategies have been published but are frequently not followed.^{10,11,12,13,14} The analgesic component for sufficient stress relief, however, has not been addressed extensively, and few recommendations, primarily based on individual clinical practices, are currently available.^15,16,17

In view of the side effects of opioids, especially respiratory depression, altered mental status, and reduced bowel function, regional analgesia utilizing neuraxial and peripheral nerve blocks offer significant advantages. The lack of a universally reliable pain assessment tool (“analgesiometer”) in the critically ill contributes to the dilemma of adequate analgesia. Many patients in the critical care unit are not able to communicate or use a conventional visual or numeric analog scale to quantify pain. Alternative assessment tools derived from pediatric^18,19,20 or geriatric²¹ practice that rely on grimacing and other physiologic responses to painful stimuli might be useful but have been inadequately studied in the intensive care unit (ICU). Changes in heart rate and blood pressure in response to nursing activities, dressing changes, or wound care can also serve as indirect measurements of pain,²² and sedation measures like the Ramsay Sedation Scale or the Riker Sedation-Agitation Scale^23,24 scale might be helpful although not specifically designed for pain assessment.

The objective of this chapter is to describe the indications, limitations, and practical aspects of continuous regional analgesic techniques in the critically ill based on the available evidence, which at the moment is limited to case reports, cohort studies, expert opinion, and extrapolation from studies looking primarily at the intraoperative use of regional anesthesia extending into the postoperative ICU stay as summarized in a 2012 systematic review in Regional Anesthesia Pain Medicine by Stundner and Memtsoudis who conclude, “Regional anesthesia can be useful in the management of a large variety of conditions and procedures in critically ill patients. Although the attributes of regional anesthetic techniques could feasibly affect outcomes, no conclusive evidence supporting this assumption exists to date, and further research is needed to elucidate this entity.”²⁵

EPIDURAL ANALGESIA

Epidural analgesia is probably the most commonly used regional analgesic technique in the ICU setting.²⁶ Some indications in which epidural analgesia may not improve mortality rates but may facilitate management and improve patient comfort in the ICU include chest trauma,^27,28,29,30 thoracic^31,32 and abdominal surgery,^5,33,34 major vascular surgery,^...