Jeffrey W. Miller

Comparison of dexmedetomidine and chloral hydrate sedation for transthoracic echocardiography in infants and toddlers: a randomized clinical trial.

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.

Patient and procedural characteristics for successful and failed immediate tracheal extubation in the operating room following cardiac surgery in infancy

Immediate extubation in the operating room after congenital heart surgery is practiced with rising frequency at many cardiac institutions to decrease costs and complications. Infants less than one year of age are also increasingly selected for this ‘fast track’. However, factors for patient selection, success, or failure of this practice have not been well defined in this population, yet are critical for patient safety.

Upper body central venous catheters in pediatric cardiac surgery.

A central venous catheter located in the jugular or subclavian vein provides rapid, reliable vascular access for pediatric heart surgery. However, intravascular catheters are associated with vessel injury. Stenosis or thrombosis of central veins in the upper body can lead to ‘superior vena cava syndrome’ with markedly elevated venous pressures in the head and neck, causing facial swelling and headaches. This complication may be especially serious for patients with superior cavopulmonary (Glenn) or total cavopulmonary (Fontan) circulation. The authors hypothesized that upper body central line placement would be associated with a low risk of venous thrombosis or stenosis.

Does intranasal dexmedetomidine provide adequate plasma concentrations for sedation in children: a pharmacokinetic study

Background: Atomised intranasal dexmedetomidine administration is an attractive option when sedation is required for paediatric diagnostic procedures, as vascular access is not required. The risk of haemodynamic instability caused by dexmedetomidine necessitates better understanding of its pharmacokinetics in young children. To date, intranasal dexmedetomidine pharmacokinetics has only been studied in adults. Methods: Eighteen paediatric patients received dexmedetomidine 1 or 2 &mgr;g kg−1 intranasally or 1 &mgr;g kg−1 i.v. Plasma concentrations were determined by liquid chromatography/mass spectrometry. Non‐compartmental analysis provided estimates of Cmax and Tmax. Volume of distribution, clearance, and bioavailability were estimated by simultaneous population PK analysis of data after intranasal and i.v. administration. Dexmedetomidine plasma concentration‐time profiles were evaluated by simulation for intranasal and i.v. administration. Results: An average peak plasma concentration of 199 pg ml−1 was achieved 46 min after 1 &mgr;g kg−1 dosing and 355 pg ml−1 was achieved 47 min after 2 &mgr;g kg−1 dosing. A two‐compartment pharmacokinetic model, with allometrically scaled parameters, adequately described the data. Typical bioavailability was 83.8% (95% confidence interval 69.5–98.1%). Conclusion: Mean arterial plasma concentrations of dexmedetomidine in infants and toddlers approached 100 pg ml−1, the low end reported for sedative efficacy, within 20 min of an atomised intranasal administration of 1 &mgr;g kg−1. Doubling the dose to 2 &mgr;g kg−1 reached this plasma concentration within 10 min and achieved almost twice the peak concentration. Peak plasma concentrations with both doses were reached within 47 min of intranasal administration, with an overall bioavailability of 84%.

Intranasal dexmedetomidine with and without buccal midazolam for procedural sedation in autistic children: a double-blind randomised controlled trial

Abstract Background Children with autism are often difficult to manage in the hospital setting, and they often require sedation for diagnostic procedures. Intranasal dexmedetomidine has been used increasingly in children for procedural sedation. This study was designed to compare the successful sedation rate of intranasal dexmedetomidine with and without buccal midazolam on children with autism. Methods This single-centre, double-blind randomised controlled trial was approved and conducted in the Guangzhou Women and Childrens Medical Centre, China. Children aged 1–12 years with a diagnosis of autism who required sedation for a CT study or an auditory brainstem response test (ABR), or both, were recruited. Exclusion criteria included known allergy or hypersensitivity to dexmedetomidine or midazolam, renal or hepatic dysfunction, nasal discharge, or rhinorrhea. Children were randomly assigned to receive either dexmedetomidine with placebo (group D) or dexmedetomidine with midazolam (group DM). Randomisation lists with block of 6 and age stratification (1–4, 5–8, and 9–12 years) were produced by an independent statistician. All participants and investigators were masked to group allocation. Children assigned to group D received 3 μg/kg of intranasal dexmedetomidine by atomiser and buccal placebo in the form of syrup, children assigned to group DM received 3 μg/kg of intranasal dexmedetomidine with 0·2 mg/kg of buccal midazolam (5 mg/mL) mixed with simple syrup. The primary outcome was the proportion of participants with sedation success allowing completion of CT, ABR, or concurrent CT and ABR test without restrain. We analysed the success rate using the χ 2 test. This study was approval by the Institutional Review Board of Guangzhou Women and Children Medical Centre (approval number 2013053110) and registered with the Chinese Clinical Trial Registry (ChiCTR-TRC-14004761). Informed consent was obtained from parents or legal guardians. Findings Between June 9, 2014, and Nov 9, 2015, 192 children completed the study, 97 were assigned to group D and 95 to group DM. 82 children from group D and 91 from group DM had CT studies. 51 children from group D and 55 children from group DM had ABR. Among these children, 38 children from group D and 49 from group DM had concurrent CT and ABR test. The success rate was significantly higher in the group DM than in the group D for CT (86/91 [94·5%] vs 67/82 [81·7%]; p=0·009), ABR (38/55 [69·1%] vs 25/51 [49·0%]; p=0·035], and for concurrent CT and ABR (32/49 [65·3%] vs 16/38 [42·1%]; p=0·031). No children had respiratory depression or haemodynamic disturbances that required medical intervention. Of the 95 children who received dexmedetomidine, two had hypotension and six had bradycardia. Of the children who received dexmedetomidine/midazolam, five had hypotension and nine had bradycardia. No children had concurrent hypotension and bradycardia. Interpretation When buccal midazolam was added to intranasal dexmedetomidine, 95% of children with autism were successfully sedated for CT, and over 65% for ABR. Since the administration of intranasal and buccal sedatives required little cooperation, this technique could be especially useful for sedation in children with autism. Funding Department of Anaesthesiology, Guangzhou Women and Childrens Medical Centre.

Sedation methods for transthoracic echocardiography in children with Trisomy 21—a retrospective study

Many children with Trisomy 21 have neurologic or behavioral problems that make it difficult for them to remain still during noninvasive imaging studies, such as transthoracic echocardiograms (TTEcho). Recently, intranasal dexmedetomidine sedation has been introduced for this purpose. However, dexmedetomidine has been associated with bradycardia. Children with Trisomy 21 have been reported to have a higher risk of bradycardia and airway obstruction with sedation or anesthesia compared to children without Trisomy 21.

A Case Series Characterizing Pilomyxoid Astrocytomas in Childhood.

Background:The term pilomyxoid astrocytroma (PMA) was added to the World Health Organization Classification of Tumours of the central nervous system in 2007. Pilomyxoid tumors are grade II tumors, considered to be variants of pilocytic astrocytomas. We attempted to determine if positron emission tomography (PET), proliferative index (PI), and BRAF V600E mutation help better define PMAs. Observations:We report 5 patients’ clinical and neuroimaging findings, pathology (PI), and outcome. Four of the 5 patients had PET scans. Three patients showed [18F]fluoro-deoxyglucose hypermetabolism. The PI was elevated in all 5 cases and the BRAF V600E mutation was found in 3 of the 3 patients tested. Conclusion:Our data suggest that PMAs are hypermetabolic on PET, have elevated PIs and BRAF V600E mutations, and behave aggressively.