Dexmedetomidine for sedation and perioperative management of critically ill patients

Interpatient variability in dexmedetomidine response: a survey of the literature

Fifty-five thousand patients are cared for in the intensive care unit (ICU) daily with sedation utilized to reduce anxiety and agitation while optimizing comfort. The Society of Critical Care Medicine (SCCM) released updated guidelines for management of pain, agitation, and delirium in the ICU and recommended nonbenzodiazepines, such as dexmedetomidine and propofol, as first line sedation agents. Dexmedetomidine, an alpha-2 agonist, offers many benefits yet its use is mired by the inability to consistently achieve sedation goals. Three hypotheses including patient traits/characteristics, pharmacokinetics in critically ill patients, and clinically relevant genetic polymorphisms that could affect dexmedetomidine response are presented. Studies in patient traits have yielded conflicting results regarding the role of race yet suggest that dexmedetomidine may produce more consistent results in less critically ill patients and with home antidepressant use. Pharmacokinetics of critically ill patients are reported as similar to healthy individuals yet wide, unexplained interpatient variability in dexmedetomidine serum levels exist. Genetic polymorphisms in both metabolism and receptor response have been evaluated in few studies, and the results remain inconclusive. To fully understand the role of dexmedetomidine, it is vital to further evaluate what prompts such marked interpatient variability in critically ill patients.

Evaluation of dexmedetomidine: safety and clinical outcomes in critically ill trauma patients

BACKGROUND

To compare safety and clinical outcomes of prolonged infusions with standard-dose (≤0.7 μg/kg/h) dexmedetomidine (SDD) or high-dose (>0.7 μg/kg/h) dexmedetomidine (HDD) to propofol in critically ill trauma patients.

METHODS

This was a retrospective review of 127 adult mechanically ventilated trauma patients between 2008 and 2009, who received propofol, SDD, or HDD for >24 hours. Primary outcomes were significant changes in blood pressure or heart rate. Secondary outcomes included hospital and intensive care unit (ICU) length of stay (LOS), ventilator time, and any concomitant analgesic, sedative, and antipsychotic use. Pairwise comparisons were based on Wilcoxon rank-sum test for continuous data and Pearson's chi-square test for categorical data. Statistical significance was defined as p value <0.05.

RESULTS

Patients in HDD group had higher rate of hypotension (98% vs. 78%; p = 0.02) but no significant differences in heart rate compared with propofol group. These patients had median longer hospital LOS (25 days vs. 12 days; p < 0.001), ICU LOS (20 days vs. 12 days; p = 0.004), and longer ventilator time (14 days vs. 7 days; p = 0.008). They also had increased requirements for oxycodone (74% vs. 40%; p = 0.003), midazolam (36% vs. 8%; p = 0.004), and haloperidol (50% vs. 24%; p = 0.02). Patients in SDD group had longer hospital LOS compared with propofol group (21 days vs. 13 days; p < 0.001).

CONCLUSION

Higher doses of dexmedetomidine may result in higher incidence of hypotension, longer LOS, and increased concomitant analgesic, sedative, and antipsychotic use, requiring further evaluation in trauma patients.

A new dosing protocol reduces dexmedetomidine-associated hypotension in critically ill surgical patients

BACKGROUND

Although no ideal sedative exists, dexmedetomidine is unique because it produces sedation and analgesia without decreasing the respiratory drive. Hemodynamic responses to dexmedetomidine are variable and dependent on the patient population. Our initial experience was associated with an unacceptable incidence of hypotension and bradycardia. We evaluated occurrence of hypotension and bradycardia in critically ill surgical patients receiving dexmedetomidine before and after implementation of a dosing protocol.

METHODS

This is a retrospective chart review of all admissions to a university medical center-based, 44-bed surgical intensive care unit pre and post protocol implementation.

RESULTS

Forty-four patients received dexmedetomidine including 19 historic controls and 25 dosed via protocol. Both groups had comparable demographics and initial and maximum dosages of dexmedetomidine. Use of the dosing protocol resulted in fewer dosage changes (mean +/- standard deviation, 4.8 +/- 3.8 compared to 7.8 +/- 3.9; P = .014) and fewer episodes of hypotension (16% vs 68.4%; P = .0006) but did not influence bradycardic episodes (20% vs 15.5%; P > .99).

CONCLUSION

We found that use of a protocol that increases the time interval between dosage adjustments may reduce dexmedetomidine-associated hypotension.

The importance of diagnosing and managing ICU delirium

ICU delirium represents a form of brain dysfunction that in many cohorts has been diagnosed in 60 to 85% of patients receiving mechanical ventilation. This organ dysfunction is grossly underrecognized because a majority of patients have hypoactive or "quiet" delirium characterized by "negative" symptoms (eg, inattention and a flat affect) not alarming the treating team. Hyperactive delirium, formerly called ICU psychosis, stands out because of symptoms such as agitation that may cause harm to self or staff, but is actually rare relative to hypoactive delirium and associated with a better prognosis. Delirium is often incorrectly thought to be transient and of little consequence. After adjusting for numerous covariates, delirium is a strong, independent predictor of prolonged length of stay, reintubation, higher mortality, and cost of care. Expanded work on patient safety and recommendations by professional societies have established the importance of delirium monitoring and recommended it as standard practice in ICUs all over the world. This evidence-based review for physicians, nurses, respiratory therapists, and pharmacists will outline why it is imperative that patients be routinely monitored for delirium. This review will discuss modifiable risk factors for delirium, such as metabolic disturbances or potent sedative and analgesic medications. Attention to mitigating risk factors, along with recommended pharmacologic approaches such as antipsychotic medications, may provide resolution of delirium in some patients, while others will persist with refractory brain dysfunction and long-term cognitive impairment following critical illness.

The sedation of critically ill adults: part 2: management

The prevention and treatment of pain, anxiety, and delirium in the ICU are important goals. But achieving a balance between sedation and analgesia, especially in critically ill patients on mechanical ventilation, can be challenging. Both under- and oversedation carry grave risks. Without having an agreed-upon end point for sedation, different providers will likely have disparate treatment goals, increasing the risk of iatrogenic complications and possibly impeding recovery. In 2002 the Society of Critical Care Medicine, along with the American Society of Health-System Pharmacists, updated recommendations in its clinical practice guidelines for the sustained use of sedatives and analgesics in adults. This two-part series examines those recommendations concerning sedation assessment and management, as well as the current literature. Last month, Part 1 reviewed pertinent recommendations concerning pain and delirium and discussed tools for assessing pain, delirium, and sedation. This month, Part 2 explores pharmacologic and nonpharmacologic management of anxiety and agitation in the ICU. The second in a two-part series focuses on the pharmacologic and nonpharmacologic management of anxiety and agitation in the ICU.

Dexmedetomidine: an updated review

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, alpha(2)-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 alpha(2)-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 less than 24 hours, it has been administered for longer than 24 hours without apparent development of rebound hypertension and tachycardia.

CONCLUSIONS

Dexmedetomidine is a safe and effective agent for sedation in critically ill patients. Further, well designed studies are needed to define its role as a sedative for critically ill medical, neurosurgical, and pediatric patients, as an adjunct to anesthesia, and as a sedative during procedures.