Literature Review

Reviewed by Amber Rogers, MD

Comparison of Dexmedetomidine and Chloral Hydrate Sedation for Transthoracic Echocardiography in Infants and Toddlers: A randomized clinical trial

Miller J, Xue B, Hossain M, Zhang M, Loepke A, Kurth D. Pediatr Anaesth. 2015 Nov 30.doi:10.111/pan.12819  

Background: Procedural sedation using chloral hydrate is used in many institutions to improve the quality of transthoracic echocardiograms (TTE) in infants and young children. Chloral hydrate has limited availability in some countries, creating the need for alternative effective sedatives.

Objective: The aim of our study was to compare the effectiveness of two doses of intranasal dexmedetomidine vs oral chloral hydrate sedation for transthoracic echocardiography.

Methods: This is a randomized, prospective study of 150 children under the age of three years with known or suspected congenital heart disease scheduled for transthoracic echocardiography with sedation. Group CH received oral chloral hydrate 70 mg/kg, group DEX2 received two mcg/kg intranasal dexmedetomidine, and group DEX3 received three mcg/kg intranasal dexmedetomidine. Acceptance of drug administration, sedation onset and duration, heart rate, and oxygen saturation, sonographer and parent satisfaction were recorded.

Results: All patients were successfully sedated for TTE. A second sedative dose (rescue) for failed single-dose sedation was required for 4% of patients after CH, none of the patients after DEX2, and 4% of patients after DEX3. Patients in group CH had an average heart rate decline of 22% during sedation, while group DEX2 decreased 27%, and group DEX3 23% (P = 0.2180). Mean time from administration of the sedative to final patient discharge was 96 min after CH, 83 min after DEX2, and 94 min after DEX3 (P = 0.1826).

Conclusion: Intranasal dexmedetomidine two and three mcg/kg were found to be as effective for TTE sedation as oral chloral hydrate with similar sedation onset and recovery time and heart rate changes in this study population.

Intranasal dexmedetomidine (IN DEX) has been shown to be an effective sedative for several procedures which historically have been completed using chloral hydrate such as auditory brainstem response tests (ABRs) and CT scans, but less is known about the safety and efficacy of IN DEX in children requiring sedation for TTEs.1,2,3  This is a population that would theoretically be more at risk for the mainly cardiovascular-related side effects of dexmedetomidine, meriting a thorough evaluation of the use of IN DEX for sedated TTEs. 
Li et al. published a prospective observational study using 3 mcg/kg IN DEX for sedated TTEs showing 87% of patients satisfactorily sedated with no significant adverse events; however, the study population did not include patients with cyanotic congenital heart disease.4  The above study by Miller et al offers a more rigorous assessment of IN DEX for TTEs by comparing it to oral chloral hydrate via a randomized controlled trial without excluding patients with unrepaired cyanotic congenital heart disease.  While the population recruited was more inclusive than in the Li study, the enrolled patients included just one patient with unrepaired cyanotic congenital heart disease and one patient with an ASD and baseline SpO2 of 90% on room air; there were no patients with single ventricle congenital lesions or heart transplants, limiting the applicability of the results to these populations who frequently require sedation for TTEs. 

All patients were successfully sedated, which is impressive for a non-IV sedation medication regimen evaluation, but of note, the mean TTE scan time overall was 9.3 minutes, significantly shorter that reported in other studies.  By comparison, the mean TTE duration was 21.3 +/- 9.9 min (range 7–52 min) in the Li study, and other papers have noted TTEs to average 40 minutes with some procedures taking over one hour.5  It’s unknown what the sedation success rate would have been with a longer procedure duration.

A few other particulars of the study were unusual, including the NPO time of two hours for solids and clears per the institutional guidelines of Shanghai Children’s Hospital Medical Center; this could have affected the results given that the patients were possibly less agitated from hunger or thirst than patients who have followed the ASA guidelines for NPO status.6  In addition, the patient monitoring included pulse oximetry and heart rate without blood pressure or EKG evaluation, so potential hemodynamic and cardiac rhythm disturbances resulting from the medications are unknown.  These should be evaluated in future studies.  Interestingly, though, all three groups had statistically similar decreases in heart rate and frequency of oxygen desaturation, a somewhat unexpected result given the differing side effect profiles of chloral hydrate and dexmedetomidine.  There were no serious adverse events.

This study is helpful for demonstrating how IN DEX is fairly comparable to oral chloral hydrate for sedated TTEs in a relatively “healthy cardiac” patient population, but additional studies are needed to demonstrate the safety and efficacy of IN DEX in a population with more complex cardiac lesions evaluated with TTEs of longer duration. 


  1. Reynolds JM, et al. Retrospective Comparison of Intranasal Dexmedetomidine and Oral Chloral Hydrate for Sedated Auditory Brainstem Response Exams. Hospital Pediatrics 2016 (in press).
  2. Reynolds J, et al. A prospective, randomized, double-blind trial of intranasal dexmedetomidine and oral chloral hydrate for sedated auditory brainstem response (ABR) testing. Pediatric Anesthesia 2016 (in press)
  3. Filho M, et al. Intranasal dexmedetomidine for sedation for pediatric computed tomography imaging. J Pediatrics2015.
  4. Li, B et al. Intranasal dexmedetomidine for sedation in children undergoing transthoracic echocardiography study—a prospective observational study. Pediatric Anesthesia 2015.
  5. Zilberman MV. How best to assure patient co-operation during a pediatric echocardiography examination.  Journal of the American Society of Echocardiography 2010.
  6. American Society of Anesthesiologists Task Force on Sedation and Analgesia by Non-Anesthesiologists. Practice Guidelines for Sedation and Analgesia by Non-Anesthesiologists. Anesthesiology 2002; 96:1004–17

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