Purpose of review The present review serves as an overview update in the diverse uses of the sedative dexmedetomidine. Recent findings Dexmedetomidine is a selective alpha2 adrenoreceptor agonist that has been described as a useful, safe adjunct in many clinical applications. This paper reviews current clinical uses, mechanism of action, and side effects of dexmedetomidine. The current uses reviewed include sedation in the ICU (adult and pediatric), neurosurgery, pediatric procedural sedation, awake fiber-optic intubation, cardiac surgery, and bariatric surgery. Summary Dexmedetomidine is a useful medication with many clinical applications. The medication has shown efficacy in decreasing the need for opioids, benzodiazepines, propofol, and other sedative medications. Short-term sedation has been shown to be safe in studies, although hypotension and bradycardia are the most significant side effects. Dexmedetomidine has been used effectively for sedation during pediatric procedures and in the ICU. In order to reduce sympathetic tone during cardiac surgery, a low-dose dexmedetomidine infusion has been utilized. The bariatric surgery population has also been studied with dexmedetomidine because of its adequate sedation and less prevalent respiratory depression when compared with opioid administration. Dexmedetomidine is emerging as an effective therapeutic agent in the management of a wide range of clinical conditions with an efficacious, safe profile.

Dexmedetomidine: A Review of Clinical Applications

Etomidate is a carboxylated, imidazole-containing intravenous anesthetic agent introduced into clinical anesthesia practice in 1972. Its distinctive features that make it useful as an anesthetic induction include a lack of adverse effects on hemodynamic function as well as beneficial effects on cerebral blood flow and intracranial pressure. Because of these properties, its major role in anesthetic practice has been for the induction of anesthesia in patients with diminished cardiovascular function. As opposed to the considerable reported clinical experience with etomidate in the adult population, there remains limited reported information concerning its use in pediatric patients. This article reviews the specific end-organ effects of etomidate, the reports concerning its use in pediatric patients, and its adverse effect profile.

Dexmedetomidine: applications in pediatric critical care and pediatric anesthesiology.

Objective:To review recent literature on the safety and efficacy of dexmedetomidine.Data Sources:Articles were identified through searches of MEDLINE (1966–January 2007). Key words included dexmedetomidine, medetomidine, α2-agonist, and sedation. References from selected articles were reviewed for additional references.Study Selection and Data Extraction:Experimental and observational studies that focused on the safety and efficacy of dexmedetomidine in humans were selected.Data Synthesis:Dexmedetomidine is an α2-agonist for short-term sedation in critically ill patients. In postoperative patients, dexmedetomidine produced similar levels of sedation and times to extubation, with less opioid requirements compared with propofol. Dexmedetomidine has also been studied for sedation in critically ill medical and pediatric patients, as adjunct to anesthesia, and for procedural sedation. Hypotension, hypertension, and bradycardia are common adverse effects. Although dexmedetomidine is labeled only for sedation le...

Dexmedetomidine: An Updated Review

Summary
Objective: This large-scale retrospective review evaluates the sedation profile of dexmedetomidine.

Aim:  To determine the hemodynamic responses, efficacy and adverse events associated with the use of high dose dexmedetomidine as the sole sedative for magnetic resonance imaging (MRI) studies.

Background:  Dexmedetomidine has been used at our institution since 2005 to provide sedation for pediatric radiological imaging studies. Over time, an effective protocol utilizing high dose dexmedetomidine as the sole sedative agent has evolved.

Methods/Materials:  As part of the ongoing Quality Assurance process, data on all sedations are reviewed monthly and protocols modified as needed. Data were analyzed from all 747 consecutive patients who received dexmedetomidine for MRI sedation from April 2005 to April 2007.

Results:  Since 2005, the 10-min loading dose of our dexmedetomidine protocol increased from 2 to 3 μg·kg−1, and the infusion rate increased from 1 to 1.5 to 2 μg·kg−1·h−1. The current sedation protocol progressively increased the rate of successful sedation (able to complete the imaging study) when using dexmedetomidine alone from 91.8% to 97.6% (P = 0.009), reducing the requirement for adjuvant pentobarbital in the event of sedation failure with dexmedetomidine alone and decreased the mean recovery time by 10 min (P < 0.001). Although dexmedetomidine sedation was associated with a 16% incidence of bradycardia, all concomitant mean arterial blood pressures were within 20% of age-adjusted normal range and oxygen saturations were 95% or higher.

Conclusion:  Dexmedetomidine in high doses provides adequate sedation for pediatric MRI studies. While use of high dose dexmedetomidine is associated with decreases in heart rate and blood pressure outside the established ‘awake’ norms, this deviation is generally within 20% of norms, and is not associated with adverse sequelae. Dexmedetomidine is useful as the sole sedative for pediatric MRI.

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High dose dexmedetomidine as the sole sedative for pediatric MRI.

We compared the sedative, hemodynamic, and respiratory effects of dexmedetomidine and propofol in children undergoing magnetic resonance imaging procedures. Sixty children were randomly distributed into two groups: The dexmedetomidine (D) group received 1 microg/kg initial dose followed by continuous infusion of 0.5 microg.kg(-1).h(-1) and a propofol group (P) received 3 mg/kg initial dose followed by a continuous infusion of 100 microg.kg(-1).min(-1). Inadequate sedation was defined as difficulty in completing the procedure because of the child's movement during magnetic resonance imaging. Mean arterial pressure (MAP), heart rate, peripheral oxygen saturation, and respiratory rate (RR) were recorded during the study. The onset of sedation, recovery, and discharge time were significantly shorter in group P than in group D. MAP, heart rate, and RR decreased during sedation from the baseline values in both groups. MAP and RR were significantly lower in group P than in group D during sedation. Desaturation was observed in four children of group P. Dexmedetomidine and propofol provided adequate sedation in most of the children. We conclude that although propofol provided faster anesthetic induction and recovery times, it caused hypotension and desaturation. Thus, dexmedetomidine could be an alternative reliable sedative drug to propofol in selected patients.

A comparison of the sedative, hemodynamic, and respiratory effects of dexmedetomidine and propofol in children undergoing magnetic resonance imaging.

Background We evaluated the sedative, haemodynamic and respiratory effects of dexmedetomidine and compared them with those of midazolam in children undergoing magnetic resonance imaging (MRI) procedures. Methods Eighty children aged between 1 and 7 yr were randomly allocated to receive sedation with either dexmedetomidine (group D, n=40) or midazolam (group M, n=40). The loading dose of the study drugs was administered for 10 min (dexmedetomidine 1 μg kg−1 or midazolam 0.2 mg kg−1) followed by continuous infusion (dexmedetomidine 0.5 μg kg−1 h−1 or midazolam 6 μg kg−1 min−1). Inadequate sedation was defined as difficulty in completing the procedure because of the child's movement during MRI. The children who were inadequately sedated were given a single dose of rescue midazolam and/or propofol intravenously. Mean arterial pressure (MAP), heart rate (HR), peripheral oxygen saturation (
				 S p O 2 ) and ventilatory frequency (VF) were monitored and recorded during the study. Results The quality of MRI was significantly better and the rate of adequate sedation was higher in group D than in group M (P Conclusions Dexmedetomidine provided adequate sedation in most of the children aged 1–7 yr without haemodynamic or respiratory effects during MRI procedures.

Sedative, haemodynamic and respiratory effects of dexmedetomidine in children undergoing magnetic resonance imaging examination: preliminary results

Background: The aim of the present study was to compare placebo, ketamine, granisetron and a combination of ketamine and granisetron in the prevention of shivering caused by regional anaesthesia.



Methods:  In this prospective, randomized, double-blind study, 160 ASA I and II patients undergoing urological surgery were included. Subarachnoid anaesthesia was performed in all patients with bupivacaine 15 mg. The patients were randomly allocated to receive saline (group P, n= 40), ketamine 0.5 mg (group K, n= 40), granisetron 3 mg (group G, n= 40) or ketamine 0.25 mg + granisetron 1.5 mg (group KG, n= 40). Shivering was graded as 0 = no shivering, 1 = piloerection or peripheral vasoconstriction but no visible shivering, 2 = muscular activity in only one muscle group, 3 = muscular activity in more than one muscle group but not generalized, and 4 = shivering involving the whole body. If 15 min after spinal anaesthesia and concomitant administration of a prophylactic dose of one of the study drugs, the patients shivered according to at least grade 3, the prophylaxis was regarded as ineffective and intravenous (i.v.) pethidine 25 mg was administered.



Results:  After 15 min, the number of patients with observed shivering was 22 in group P, 6 in group G, 7 in group GK and 0 in group K. The difference between group K and all the other groups was statistically significant (P < 0.0001). The number of patients with a shivering score of 3 was statistically significantly higher in group P compared with the other groups.



Conclusion:  The prophylactic use of 0.5 mg/kg i.v. ketamine was effective in preventing shivering developed during regional anaesthesia.

Control of shivering during regional anaesthesia: prophylactic ketamine and granisetron

Purpose
In this randomized, double-blind study, we aimed to compare the effectiveness of lornoxicam and ondansetron for the prevention of intrathecal fentanyl-induced pruritus in patients undergoing cesarean section

Lornoxicam and ondansetron for the prevention of intrathecal fentanyl-induced pruritus.

Study objective: To determine the effects of intra-operative low-dose dexmedetomidine infusion on postoperative morphine consumption, pain, sedation and patient satisfaction in patients undergoing septorhinoplasty. Method: Fifty adult patients were randomised to receive either dexmedetomidine (a loading dose of 1 μg kg−1 for the first ten minutes and a maintenance dose of 0.2 μg kg−1 h−1 afterwards, Group D) or 0.9% saline in the same manner (Group C) after induction of anaesthesia. At the end of the operation, the infusions were discontinued. After extubation, patient controlled analgesia was started intravenously. Results: Patients in Group D consumed 47% less morphine than patients in Group C during the first 24 h and had a lower cumulative morphine consumption at all times after starting patient controlled analgesia (7.08 mg vs. 8.56 mg at 2 h (p < 0.05), 10.84 mg vs. 14.0 mg at 4 h (p < 0.05), 13.56 mg vs. 18.28 mg at 6 h (p < 0.05) and 17.96 mg vs. 33.72 mg at 24 h (p < 0.05), respectively ...

The effects of intra-operative low-dose dexmedetomidine infusion on postoperative pain in patients undergoing septorhinoplasty

Summary Background and objective: Patients having spinal anaesthesia with hyperbaric bupivacaine may become sensitive to sedative drugs but no data exists about any dose-related effect of the local anaesthetic on the sedative requirement. We aimed to investigate whether hyperbaric bupivacaine dose in spinal anaesthesia has any effect on midazolam requirements. Methods: Sixty unpremedicated patients were allocated to three equal groups. Patients in Groups I and II received hyperbaric bupivacaine 0.5% 10 and 17.5 mg respectively for spinal anaesthesia and Group III was a control group without spinal anaesthesia. In Groups I and II, after the evaluation of sensory block, patients received intravenous midazolam 1 mg per 30 s until the Ramsay sedation score reached 3 (drowsy but responsive to command). In Group III, general anaesthesia was induced after sedation score had reached 3 using midazolam. The total dose of midazolam (mg kg � 1 ) given to each patient, the level of sensory block and complications were recorded. Results: The level of sensory block was higher in Group II (T7) than Group I (T9) (P � 0.01). The doses of midazolam were 0.063 mg kg � 1 in Group I, 0.065 mg kg � 1 in Group II and 0.101 mg kg � 1 in Group III (P � 0.001). There was no correlation between level of sensory block and dose of midazolam in Group I (r � � 0.293, P � 0.21) and Group II (r � 0.204, P � 0.39). Conclusions: Different doses of hyperbaric bupivacaine for spinal anaesthesia do not affect the midazolam requirements for sedation. However, spinal anaesthesia with hyperbaric bupivacaine with a maximum spread in the middle thoracic dermatomes may be associated with sedative effects and thus a reduced need for further sedation with midazolam.

Özlem Sağır

Papers

Sedative, haemodynamic and respiratory effects of dexmedetomidine in children undergoing magnetic resonance imaging examination: preliminary results

Control of shivering during regional anaesthesia: prophylactic ketamine and granisetron

Lornoxicam and ondansetron for the prevention of intrathecal fentanyl-induced pruritus.

The effects of intra-operative low-dose dexmedetomidine infusion on postoperative pain in patients undergoing septorhinoplasty

Hyperbaric bupivacaine affects the doses of midazolam required for sedation after spinal anaesthesia.