Comparison of Pain and Comfort in Patients Following Cardiac Surgery: Opioid- Morphine Managed Versus Multimodal Pain-management

Cardiac surgery for the adult, performed by sternotomy is associated with moderate to severe acute postoperative pain. Postoperative pain is the primary reason for prolonged convalescence and one of the main concerns of the surgical patient in the Intensive Care Unit (ICU). This pain is multifactorial and multifocal; and can be caused by incision, intraoperative tissue retraction and dissection, surgical manipulation of the parietal pleura, posterior rib dislocation or fracture, possible brachial plexus injury, chest tube insertion and harvesting of the saphenous vein and internal mammarian artery.

The most common analgesic schemes for postoperative pain in cardiac surgery are based on intravenous opioids by bolus, with patient- or nurse-controlled delivery systems. Although there is no doubt they have a beneficial effect on pain, opioids are associated with dose-related side effects including "over"sedation, ileus, urinary retention, nausea, vomiting, pruritus, mental confusion and respiratory depression leading to a prolonged extubation time.

In the last decades many has been written about the value of multimodal pain protocols to treat acute postoperative pain in non-cardiac surgery. This is not only to reduce the dose and side effects of opioids. By blocking both the central and peripheral pain mechanisms the aim is to find a holy grale, by which the patient suffers the least, by which central neural hyper-excitability that increases postoperative pain is minimized and by which the transformation of acute into chronic pain is reduced to a minimum.

Pregabalin has his role in treating various neuropathic pain syndromes. It inhibits central neuronal sensitization and prevents hyperalgesia by decreasing excitatory amino acid neurotransmission in the spinal cord through a direct postsynaptic or presynaptic inhibition of Ca²+ influx. It has been shown that gabapentin reduced pain scores and opioid requirements in different surgical settings. Literature is not conclusive and because of conflicting results the routine use of gabapentin and pregabalin to reduce opioid consumption in the cardiac surgical patients is not yet recommended.

Dexmedetomidine is an alpha-2 adrenergic receptor agonist that can be directly applied to the peripheral nervous system, causing a dose-dependent inhibition of C-fibers and Aα-fibers. It is widely used for sedation and anxiolysis in ICU settings. The clinical efficacy has been proven in non-cardiac surgery by augmenting anesthesia and analgesia, and allowing a reduction in opioid requirements. Additionally, there was a significantly lower incidence of postoperative delirium.