To pretreat or not to pretreat: prophylactic anticholinergic administration before dexmedetomidine in pediatric imaging. (Betters)

Subramanyam R, et al. To pretreat or not to pretreat: prophylactic anticholinergic administration before dexmedetomidine in pediatric imaging. Anesth Analg. 2015 Aug;121(2):479-85.

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BACKGROUND: Dexmedetomidine (Dex) appears to be very effective as a sole sedative for pediatric imaging when used at high doses, but at an increased risk of transient hypertension, hypotension, and bradycardia. There are no clinical evidence/guidelines to guide anesthesia providers as to whether patients should be pretreated with ananticholinergic. The aim of this study was to demonstrate the changes in hemodynamic parameters after Dex sedation attributed to receiving or not receiving an anticholinergic pretreatment and compare for any differences or similarities. A subgroups analysis was performed in children with Down syndrome (DS).

METHODS: In this retrospective descriptive study, we reviewed the records of 163 children receiving Dex anesthesia during MRI studies. Data analyzed included demographics, history of DS, and hemodynamics (heart rate [HR], systolic blood pressure [SBP], and diastolic blood pressure [DBP]) following Dex loading and infusion and the administration of an anticholinergic (atropine or glycopyrrolate).

RESULTS: The mean age was 94.5 months, and 52 (32%) patients had DS. The generalized linear mixed-effects regression model showed a significant reduction in HR and SBP in all patients when no anticholinergic was administered compared with when it was administered. There was no significant change with DBP. During the scan period, the HR of the no-anticholinergic group decreased 26.6%, whereas that of the anticholinergic group decreased by only 16.7% from baseline (P < 0.01). The maximal SBP increased by a significantly greater percentage, compared with baseline, in the anticholinergic group in comparison with the no-anticholinergic group (20.2% vs 10.4%, respectively; P = 0.02). In the DS group, the difference in the maximal SBP change during the scan period was exaggerated, with a percentage increase that was 36 times larger in the anticholinergic group compared with the no-anticholinergic group (22% vs 0.6%, respectively; P< 0.01).

CONCLUSIONS: Administration of a prophylactic anticholinergic with Dex shows no advantage other than a transient clinically insignificant increase in HR and SBP, and it may precipitate transient exaggerated SBP in more patients compared with not using a prophylactic anticholinergic.

Intraoperative dexmedetomidine reduces postoperative mechanical ventilation in infants after open heart surgery. (Emrath)

Achuff BJ, Nicolson SC, Elci OU, Zuppa AF. Intraoperative dexmedetomidine
reduces postoperative mechanical ventilation in infants after open heart surgery.
Pediatr Crit Care Med. 2015 Feb 21. [Epub ahead of print]

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OBJECTIVE: The inclusion of dexmedetomidine in the operative and postoperative management of infants with congenital heart defects has lessened the need for opioids that may cause respiratory depression. Our objective was to show that a dexmedetomidine bolus at or about the time of sternal closure is associated with a decrease in the use of mechanical ventilation in the immediate postoperative period.

DESIGN: Retrospective cohort study.

SETTING: Single pediatric tertiary cardiac center.

PATIENTS: Infants undergoing surgical intervention for congenital heart defects requiring cardiopulmonary bypass, age 30-365 days in a 5-year time period from June 1, 2008, to December 31, 2012.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN RESULTS: Of 1,057 total encounters, 441 met inclusion criteria and were evenly distributed over the 5-year time period. Dexmedetomidine had been given at or about the time of sternal closure in 57% of patients. When the exposed and unexposed groups were compared in terms of mechanical ventilation immediately postoperative, there was a statistically significant effect of using dexmedetomidine on the odds of receiving mechanical ventilation (p = 0.0019). This difference remained significant after adjusting for covariates affecting the decision for mechanical ventilation, including year of the procedure, age and weight of subject, cardiopulmonary bypass time, the use of deep hypothermic circulatory arrest, intraoperative fentanyl dose, and the Risk Adjustment for Congenital Heart Surgery Score 1 (p = 0.0317). The odds of receiving mechanical ventilation are estimated to be two times higher for patients who did not receive dexmedetomidine than for patients who received dexmedetomidine after adjusting for variables.

CONCLUSION: The use of dexmedetomidine bolus in the operating room at the time of sternal closure in infants undergoing open heart surgery is associated with reduced need for mechanical ventilation in the immediate postoperative period.

A comparison of severe hemodynamic disturbances between dexmedetomidine and propofol for sedation in neurocritical care patients. (Teppa)

Erdman MJ, Doepker BA, Gerlach AT, Phillips GS, Elijovich L, Jones GM. A comparison of severe hemodynamic disturbances between dexmedetomidine and propofol for sedation in neurocritical care patients. Crit Care Med. 2014 Jul;42(7):1696-702.

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OBJECTIVE: Dexmedetomidine and propofol are commonly used sedatives in neurocritical care as they allow for frequent neurologic examinations. However, both agents are associated with significant hemodynamic side effects. The primary objective of this study is to compare the prevalence of severe hemodynamic effects in neurocritical care patients receiving dexmedetomidine and propofol.

DESIGN: Multicenter, retrospective, propensity-matched cohort study.

SETTING: Neurocritical care units at two academic medical centers with dedicated neurocritical care teams and board-certified neurointensivists.

PATIENTS: Neurocritical care patients admitted between July 2009 and September 2012 were evaluated and then matched 1:1 based on propensity scoring of baseline characteristics.

INTERVENTIONS: Continuous sedation with dexmedetomidine or propofol.

MEASUREMENTS AND MAIN RESULTS: A total of 342 patients (105 dexmedetomidine and 237 propofol) were included in the analysis, with 190 matched (95 in each group) by propensity score. The primary outcome of this study was a composite of severe hypotension (mean arterial pressure < 60 mm Hg) and bradycardia (heart rate < 50 beats/min) during sedative infusion. No difference in the primary composite outcome in both the unmatched (30% vs 30%, p = 0.94) or matched cohorts (28% vs 34%, p = 0.35) could be found. When analyzed separately, no differences could be found in the prevalence of severe hypotension or bradycardia in either the unmatched or matched cohorts.

CONCLUSIONS: Severe hypotension and bradycardia occur at similar prevalence in neurocritical care patients who receive dexmedetomidine or propofol. Providers should similarly consider the likelihood of hypotension or bradycardia before starting either sedative.

The hemodynamic response to dexmedetomidine loading dose in children with and without pulmonary hypertension. (Kamat)

Friesen RH, Nichols CS, Twite MD, Cardwell KA, Pan Z, Pietra B, Miyamoto SD, Auerbach SR, Darst JR, Ivy DD. The hemodynamic response to dexmedetomidine loading dose in children with and without pulmonary hypertension. Anesth Analg. 2013 Oct;117(4):953-9.

BACKGROUND: Dexmedetomidine, an α-2 receptor agonist, is widely used in children with cardiac disease. Significant hemodynamic responses, including systemic and pulmonary vasoconstriction, have been reported after dexmedetomidine administration. Our primary goal of this prospective, observational study was to quantify the effects of dexmedetomidine initial loading doses on mean pulmonary artery pressure (PAP) in children with and without pulmonary hypertension.

METHODS: Subjects were children undergoing cardiac catheterization for either routine surveillance after cardiac transplantation (n = 21) or pulmonary hypertension studies (n = 21). After anesthetic induction with sevoflurane and tracheal intubation, sevoflurane was discontinued and anesthesia was maintained with midazolam 0.1 mg/kg IV (or 0.5 mg/kg orally preoperatively) and remifentanil IV infusion 0.5 to 0.8 μg/kg/min. Ventilation was mechanically controlled to maintain Pco2 35 to 40 mm Hg. When end-tidal sevoflurane was 0% and fraction of inspired oxygen (Fio2) was 0.21, baseline heart rate, mean arterial blood pressure, PAP, right atrial pressure, pulmonary artery occlusion pressure, right ventricular end-diastolic pressure, cardiac output, and arterial blood gases were measured, and indexed systemic vascular resistance, indexed pulmonary vascular resistance, and cardiac index were calculated. Each subject then received a 10-minute infusion of dexmedetomidine of 1 μg/kg, 0.75 μg/kg, or 0.5 μg/kg. Measurements and calculations were repeated at the conclusion of the infusion.

RESULTS: Most hemodynamic responses were similar in children with and without pulmonary hypertension. Heart rate decreased significantly, and mean arterial blood pressure and indexed systemic vascular resistance increased significantly. Cardiac index did not change. A small, statistically significant increase in PAP was observed in transplant patients but not in subjects with pulmonary hypertension. Changes in indexed pulmonary vascular resistance were not significant.

CONCLUSION: Dexmedetomidine initial loading doses were associated with significant systemic vasoconstriction and hypertension, but a similar response was not observed in the pulmonary vasculature, even in children with pulmonary hypertension. Dexmedetomidine does not appear to be contraindicated in children with pulmonary hypertension.

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