Pain: According to the International Association for the study of pain, “It is an unpleasant and sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.”
Pain is frequently the result of nocioception, an activity in the nervous system that result from the stimulation of nocioceptors.
Sedation: The American College of Emergency Physicians (ACEP) defines the procedural sedation as “a technique of administering sedatives or dissociative agents with or without analgesics to induce a state that allows the patient to tolerate unpleasant procedures while maintaining cardiorespiratory function. Procedural sedation and analgesia (PSA) is intended to result in a depressed level of consciousness that allows the patient to maintain oxygenation and airway control independently.”
MIDAZOLAM: It is the benzodiazepine drug which is most commonly used for procedural sedation2 and analgesia (PSA), as it has a faster onset of sedation, more amnesia, less pain on injection, and improved awakening. Midazolam possesses a relatively high volume of distribution (Vd) compared with other benzodiazepines because of its lipophilicity. The Vd is greatly increased in obese patients, resulting in an increased half-life from 2.7 hours to 8.4 hours. It is cleared by the hepatic hydroxylation to 1-hydroxymidazolam.
FENTANYL: Fentanyl is a synthetic opioid medication. It is used in combination with anesthesia to prevent pain during or postoperative period. It has a prompt onset and shorter duration of action. It has minimal cardiovascular depressive effects and hypotension rarely occurs. It binds with opioid receptors at many sites within the CNS and increases the pain threshold, inhibits the ascending pain pathways and thus alters the pain reception. In addition to the analgesia, it also suppress the cough reflex and cause respiratory depression, drowsiness, and sedation. The half-life of fentanyl is 2-4 hours.
DEXMEDETOMIDINE: It is an alpha2-adrenergic agonist. It provides, analgesia, sedation11, anxiolysis, hypnosis and sympatholysis. It provides very little or no respiratory depression. The patients are able to respond and follow verbal commands but fall quickly asleep when not stimulated. It also provide some pain relief, like ketamine, but not to the same degree. This makes the use of other analgesics necessary for the more painful procedures while using it. The cardiovascular effects are minimal and include mild bradycardia and a decrease in systemic vascular resistance. The onset of action is relatively rapid and the context-sensitive half-time is approximately 4 minutes after a 10-minute infusion. It is upto 1600 times more selective for the alpha2 than alpha1 receptors and therefore has a very few side effects.