Preliminary experience with dexmedetomidine in the treatment of cyclic vomiting syndrome

Cyclic Vomiting Syndrome in Children

Cyclic Vomiting Syndrome (CVS) is an underdiagnosed episodic syndrome characterized by frequent hospitalizations, multiple comorbidities, and poor quality of life. It is often misdiagnosed due to the unappreciated pattern of recurrence and lack of confirmatory testing. CVS mainly occurs in pre-school or early school-age, but infants and elderly onset have been also described. The etiopathogenesis is largely unknown, but it is likely to be multifactorial. Recent evidence suggests that aberrant brain-gut pathways, mitochondrial enzymopathies, gastrointestinal motility disorders, calcium channel abnormalities, and hyperactivity of the hypothalamic-pituitary-adrenal axis in response to a triggering environmental stimulus are involved. CVS is characterized by acute, stereotyped and recurrent episodes of intense nausea and incoercible vomiting with predictable periodicity and return to baseline health between episodes. A distinction with other differential diagnoses is a challenge for clinicians. Although extensive and invasive investigations should be avoided, baseline testing toward identifying organic causes is recommended in all children with CVS. The management of CVS requires an individually tailored therapy. Management of acute phase is mainly based on supportive and symptomatic care. Early intervention with abortive agents during the brief prodromal phase can be used to attempt to terminate the attack. During the interictal period, non-pharmacologic measures as lifestyle changes and the use of reassurance and anticipatory guidance seem to be effective as a preventive treatment. The indication for prophylactic pharmacotherapy depends on attack intensity and severity, the impairment of the QoL and if attack treatments are ineffective or cause side effects. When children remain refractory to acute or prophylactic treatment, or the episode differs from previous ones, the clinician should consider the possibility of an underlying disease and further mono- or combination therapy and psychotherapy can be guided by accompanying comorbidities and specific sub-phenotype. This review was developed by a joint task force of the Italian Society of Pediatric Gastroenterology Hepatology and Nutrition (SIGENP) and Italian Society of Pediatric Neurology (SINP) to identify relevant current issues and to propose future research directions on pediatric CVS.

A Comparison of Dexmedetomidine and Midazolam for the Prevention of Postoperative Nausea and Vomiting Caused by Hemabate in Cesarean Delivery: A Randomized Controlled Trial

Objective

To compare the efficacy of dexmedetomidine and midazolam in the prevention of postoperative nausea and vomiting (PONV) caused by hemabate in postpartum hemorrhage during cesarean delivery.

Methods

One hundred and five parturients with American Society of Anesthesiology (ASA) physical status I and II, aged 20–40 years, undergoing elective cesarean delivery under epidural anesthesia were randomly allocated into dexmedetomidine group (group D, n=35), midazolam group (group M, n=35) and control group (group C, n=35). Patients received an intrauterine injection of 250 μg hemabate and continuous intravenous infusion of 5 units oxytocin immediately following the delivery of the infant. At the same time, patients in group D received 1μg/kg intravenous dexmedetomidine, group M received 0.02 mg/kg intravenous midazolam and group C received 20 mL intravenous saline. Parameters such as the PONV, other adverse reactions (chest distress, flush, etc.) caused by hemabate, patient satisfaction, the sedation (OAA/S) scores, and the hemodynamic parameters were recorded in both groups.

Results

The PONV incidence in group D and group M was significantly lower compared with group C (6%, 17%, and 71% for group D, group M, and group C, respectively, P<0.05). The sedation (OAA/S) scores in group D and group M was significantly higher compared with group C (1.62±0.28, 1.75±0.31, and 1.00±0.00 for group D, group M, and group C, respectively, P<0.05). The patient satisfaction in group D and group M was significantly higher compared with group C (94%, 69%, and 46% for group D, group M, and group C, respectively, P<0.05). Furthermore, there were more patients satisfied with group D than group M (94% vs.69%, P<0.05).

Conclusion

Intravenous dexmedetomidine (1 μg/kg) and midazolam (0.02 mg/kg) were equally effective in preventing PONV introduced by hemabate and dexmedetomidine is superior to midazolam in patient satisfaction.

Acute Management of Pediatric Cyclic Vomiting Syndrome: A Systematic Review

OBJECTIVES

To synthesize quantitative and qualitative data on pharmacologic interventions of pediatric cyclic vomiting syndrome and their effectiveness in disease management in the acute care setting.

STUDY DESIGN

Using keywords, 799 studies published up from December 1954 to February 2018 were extracted from MEDLINE via Pubmed, Embase via OVID, CINAHL via EBSCO, and Cochrane Controlled Trials Registry. Studies were evaluated for inclusion and exclusion by 2 independent reviewers using predetermined inclusion and exclusion criteria.

RESULTS

The search yielded 84 studies for full review, of which 54 were included in the systematic review. Studies were subsequently separated into 1 group of 6 case series studies containing quantitative data on sumatriptan, ondansetron, phenothiazines, prokinetic agents, carbohydrate, isometheptene, and aprepitant; 1 one group consisting only of qualitative studies containing expert recommendations.

CONCLUSIONS

Ondansetron has the most quantitative and qualitative evidence to support its inclusion in pediatric emergency department protocols as a rescue therapy. Sumatriptan and aprepitant are potential candidates for inclusion as abortive therapies. Qualitative data from retrospective studies and case reports are not applicable to a larger patient population. This report informs a need for controlled, prospective cohort studies and randomized, controlled trials to optimize current management protocols and to develop new medical interventions.

Cyclic Vomiting Syndrome in Children and Adults: What Is New in 2018?

PURPOSE OF REVIEW

Cyclic vomiting syndrome (CVS) is a disabling functional gastrointestinal disorder characterized by severe vomiting episodes that alternate with symptom-free periods. The purpose of this review is to summarize current knowledge and highlight most recent data on prevalence, diagnosis, management, and impact of CVS in children and adults.

RECENT FINDINGS

Originally thought to be a pediatric disorder, the past decade has witnessed a considerable increase in CVS diagnosed in adults. Despite improved recognition of CVS, without a delineated pathophysiology and specific biomarker, it remains classified as a functional gastrointestinal disorder. Migraines and CVS share a common pathway based on several studies and response to migraine therapy. Recent work has begun to expand the list of comorbidities and identify plausible mechanisms and new therapeutic avenues. This review seeks to highlight best practices and novel therapies for CVS based on expert consensus and review of available literature.

Managing cyclic vomiting syndrome in children: beyond the guidelines

Cyclic vomiting syndrome (CVS) in children is characterized by frequent hospitalizations, multiple comorbidities, and poor quality of life. In the absence of robust data, the treatment of CVS remains largely empiric starting with the 2008 NASPGHAN Consensus Statement recommendations of cyproheptadine for children < 5 years of age and amitriptyline for those ≥ 5 years with propranolol serving as the second-line agent. Comprehensive management begins with lifestyle alterations, and extends to medications, supplements, and stress reduction therapies. Standard drug therapy is organized by the four phases of the illness: (1) interictal (preventative medications and mitochondrial supplements), (2) prodromal (abortive agents), (3) vomiting (fluids/energy substrates, antiemetics, analgesics, and sedatives) and (4) recovery (supportive care and nutrition). Because the response to treatment is heterogeneous, clinicians often trial several different preventative strategies including NK1 antagonists, cautious titration of amitriptyline to higher doses, anticonvulsants, Ca²⁺-channel blockers, and other TCA antidepressants. When the child remains refractory to treatment, reconsideration of possible missed diagnoses and further mono- or combination therapy and psychotherapy can be guided by accompanying comorbidities (especially anxiety), specific subphenotype, and when available, genotype. For hospital intervention, IV fluids with 10% dextrose, antiemetics, and analgesics can lessen symptoms while effective sedation in some instances can truncate severe episodes.

CONCLUSION

Although management of CVS remains challenging to the clinician, approaches based upon recent literature and accumulated experience with subgroups of patients has led to improved treatment of the refractory and hospitalized patient. What is Known: • Cyclic vomiting syndrome is a complex disorder that remains challenging to manage. • Previous therapy has been guided by the NASPGHAN Consensus Statement of 2008. What is New: • New prophylactic approaches include NK1 antagonists and higher dosages of amitriptyline. • Strategies based upon comorbidities and subphenotype are helpful in refractory patients.

Definition of "persistent vomiting" in current medical literature: A systematic review

BACKGROUND AND AIM

Persistent vomiting is mentioned as a symptom of a large variety of systemic disorders. It is commonly used interchangeably with chronic, recurrent, or intractable vomiting and widely used as a warning sign of severe illness in dengue infection. However, it has been poorly defined in the medical literature. Therefore, we aimed to systematically review a definition of persistent vomiting in the medical literature.

METHODS

A systematic search was done through; PubMed, Google Scholar, Web of Science, Scopus, VHL, WHO-GHL, Grey Literature Report, POPLINE, and SIGLE for the last 10 years. Consensus on the definition was considered to be reached if at least 50% of studies described the same definition using the Delphi consensus technique.

RESULT

Of 2362 abstracts reviewed, 15 studies were selected based on the inclusion criteria. Three studies used the same definition. Another 2 studies defined it as vomiting of all foods and fluid in 24 hours. Three studies defined persistent vomiting in the units of days or weeks. Four studies used the number of episodes: ≥2 episodes 15 minutes apart, >3 episodes in 12 hours, and >3 episodes within 24 hours.

CONCLUSION

No consensus for the definition was found among authors. This is a point of concern that needs to be addressed by further studies.

Cyclical vomiting syndrome: Recognition, assessment and management

Cyclical vomiting syndrome (CVS) is a functional, debilitating disorder of childhood frequently leading to hospitalization. Affected children usually experience a stereotypical pattern of vomiting though it may vary between different individuals. The vomiting is intense often bilious, and accompanied by disabling nausea. Identifiable precipitating factors for CVS include psychosocial stressors, infections, lack of sleep and occasionally even food triggers. Often, it may be difficult to distinguish episodes of CVS from other causes of acute abdomen and altered consciousness. Thus, the diagnosis of CVS remains largely one of exclusion. Investigations routinely done during the work-up of a child with suspected CVS include both blood and imaging modalities. Plasma lactate, ammonia, amino acid and acylcarnitine profiles as well as urine organic acid profile are indicated to exclude inborn errors of metabolism. The treatment remains challenging and targeted at prevention or shortening of the attacks and can be considered as abortive, supportive and prophylactic. Use of non-pharmacological therapy is also part of the management of CVS. The prognosis of CVS is variable. More insight into the pathogenesis of this disorder as well as role of non-pharmacological therapy is needed.

A randomised study of intranasal dexmedetomidine and oral ketamine for premedication in children

We studied the effects of intranasal dexmedetomidine combined with oral ketamine for premedication in children. One hundred and sixty children aged between 2 and 6 years were randomly allocated to one of four groups: 1 μg.kg(-1) intranasal dexmedetomidine with 3 mg.kg(-1) oral ketamine (Group 1); 1 μg.kg(-1) intranasal dexmedetomidine with 5 mg.kg(-1) oral ketamine (Group 2); 2 μg.kg(-1) intranasal dexmedetomidine with 3 mg.kg(-1) oral ketamine (Group 3); and 2 μg.kg(-1) intranasal dexmedetomidine with 5 mg.kg(-1) oral ketamine (Group 4). Sedation levels 10, 20 and 30 min after premedication were evaluated using a 5-point sedation scale. A 4-point emotional state score was used to evaluate patients when they were separated from their parents and their response to intravenous cannulation or facemask application. Approximately 90% of patients readily accepted premedication and onset times of acceptable sedation were similar in all four groups. Patients in Group 4 were significantly more sedated than those in Group 1 after 30 min (p = 0.036). A significantly higher proportion of patients in Group 3 (84%) and Group 4 (87%) accepted intravenous cannulation compared with those in Group 1 (40%) and Group 2 (54%) (p = 0.001). We conclude that the administration of 2 μg.kg(-1) intranasal dexmedetomidine and 3 mg.kg(-1) oral ketamine was the optimal combination, with children being easily separated from their parent, accepting intravenous cannulation and without causing excessive side-effects or postoperative complications.

Comparison of the effects of dexmedetomidine, ketamine, and placebo on emergence agitation after strabismus surgery in children

BACKGROUND

Children undergoing strabismus surgery under sevoflurane anesthesia often experience emergence agitation (EA) and postoperative vomiting (POV). This study compared the effects of intraoperative dexmedetomidine, ketamine, and placebo on postoperative EA and POV.

METHODS

Eighty-four children (aged two to seven years) undergoing elective strabismus surgery under sevoflurane anesthesia were randomly assigned to one of three groups (n = 28 each). Intraoperatively, the placebo, dexmedetomidine, and ketamine groups received normal saline, dexmedetomidine 1 μg·kg(-1) iv plus a 1 μg·kg(-1)·hr(-1) infusion, and ketamine 1 mg·kg(-1) iv plus a 1 mg·kg(-1)·hr(-1) infusion, respectively. Agitation scores (Pediatric Anesthesia Emergence Delirium [PAED] scale) and POV were assessed in the postanesthetic care unit (PACU) and for 24 hr on the ward. Pain scores and times to laryngeal mask airway (LMA™) removal, resumption of mental orientation, and discharge from the PACU were also assessed.

RESULTS

Seventy-eight children completed the study. Peak PAED scores for EA were lower in the dexmedetomidine (P < 0.001) and ketamine (P = 0.002) groups than in the placebo group. Incidence of POV was lower in the dexmedetomidine group (15%) than in the ketamine (44%; P = 0.02) or placebo (45.8%; P = 0.02) groups. Pain scores on the ward were lower in the dexmedetomidine (P < 0.001) and ketamine (P < 0.001) groups than in the placebo group. Time to LMA removal was similar in all groups. Time for resumption of mental orientation and time to discharge from PACU were longer in the dexmedetomidine and ketamine groups than in the placebo group.

CONCLUSIONS

Dexmedetomidine and ketamine appear to prevent postoperative agitation and pain after sevoflurane anesthesia for pediatric strabismus surgery. Dexmedetomidine also prevents POV.

Treatment of cyclic vomiting syndrome

Cyclic vomiting syndrome (CVS) is a relatively rare but highly incapacitating disorder. It is seen both in children and adults, although classically it has been perceived as a pediatric gastrointestinal disorder. Recent studies have demonstrated that this disorder indeed can be seen in adults and is highly disabling. Although classically associated with migraine headaches in the pediatric form, this relationship is less well established in adults. This has major implications for management in that traditionally, one of the major avenues for treatment of pediatric CVS has been antimigraine drugs. An additional factor that obscures a review of CVS treatment is the fact that because of its relative rarity, no randomized controlled trials (RCTs) have been performed. In the absence of RCTs, it is difficult to make definitive recommendations regarding treatment. The literature to date consists of case reports and open-ended case series. However, despite these limitations, it is the goal of this article to present in a comprehensive manner the options available for the treatment of CVS. Recognizing the limitations in the literature, it is clear that a number of treatment strategies that can often prove effective for the treatment of these complicated and often-challenging patients are available. Treatment is divided between acute intervention, when a patient is actively and severely vomiting, and prophylactic treatment for patients in their "interictal" phase, the goal of which is reducing frequency and intensity of subsequent episodes. Finally, we are beginning to identify possible mechanisms of the cause of CVS. Once these are better understood, this will provide the basis for further improvement in treatment.

Dexmedetomidine: perioperative applications in children

Dexmedetomidine is a highly specific and selective alpha-2-adrenergic agonist with sedative, anxiolytic, and organ protective effects. Its clinical applications in children include premedication, prevention of emergence delirium, as part of multimodal anesthetic regimen and sedation in the pediatric intensive care unit. Its role in neuroprotection in children undergoing anesthesia should be explored. In this review, various uses of dexmedetomidine are discussed in detail.

Dexmedetomidine Use in Pediatric Intensive Care and Procedural Sedation

OBJECTIVE

Dexmedetomidine was approved by the Food and Drug Administration in 1999 for the sedation of adults receiving mechanical ventilation in an intensive care setting. It provides sedation with minimal effects on respiratory function and may be used prior to, during, and following extubation. Based on its efficacy in adults, dexmedetomidine is now being explored as an alternative or adjunct to benzodiazepines and opioids in the pediatric intensive care setting. This review describes the studies evaluating the safety and efficacy dexmedetomidine in infants and children and provides recommendations on dosing and monitoring.

METHODS

The MEDLINE (1950–November 2009) database was searched for pertinent abstracts, using the key term dexmedetomidine. Additional references were obtained from the bibliographies of the articles reviewed and the manufacturer. All available English-language case reports, clinical trials, retrospective studies, and review articles were evaluated.

RESULTS

Over two dozen case series and clinical studies have documented the utility of dexmedetomidine as a sedative in children requiring mechanical ventilation or procedural sedation. In several papers, dexmedetomidine use resulted in a reduction in the dose or discontinuation of other sedative agents. It may be of particular benefit in children with neurologic impairment or in those who do not tolerate benzodiazepines. The most frequent adverse effects reported with dexmedetomidine have been hypotension and bradycardia, in 10% to 20% of patients. These effects typically resolve with dose reduction.

CONCLUSIONS

Dexmedetomidine offers an additional choice for the sedation of children receiving mechanical ventilation in the intensive care setting or requiring procedural sedation. While dexmedetomidine is well tolerated when used at recommended doses, it has the potential to cause hypotension and bradycardia and requires close monitoring. In addition to clinical trials currently underway, larger controlled studies are needed to further define the role of dexmedetomidine in pediatric intensive care.

Successful use of dexmedetomidine for sedation in a 24-week gestational age neonate

OBJECTIVE

To describe a case of dexmedetomidine use for sedation in a 24-week gestational age premature neonate.

CASE SUMMARY

A 9-day-old, 24-week gestational age male neonate on high-frequency oscillatory mechanical ventilation was experiencing severe agitation refractory to high-dose intravenous narcotics and benzodiazepines. Since the infant's respiratory stability was reliant on adequate sedation, he was given dexmedetomidine after several days of suboptimal response to escalation of standard agents. Treatment prior to dexmedetomidine included continuous-infusion fentanyl 10 microg/kg/h, intravenous lorazepam 0.6 mg/kg every 4 hours, intermittent doses of both lorazepam and midazolam as needed, and a single bolus dose of phenobarbital. The patient calmed markedly during the dexmedetomidine loading dose infusion and remained adequately sedated while the drug was continued. The dexmedetomidine infusion allowed weaning of mechanical ventilation settings and eventual extubation of the infant, as well as rapid tapering of other sedative medications. The maximum dexmedetomidine infusion rate was 0.7 microg/kg/h, and total duration of therapy was 19 days. No significant adverse effects were directly attributed to dexmedetomidine use during this time.

DISCUSSION

Dexmedetomidine is a novel alpha(2)-agonist approved for short-term sedation in mechanically ventilated adults. Data describing its use in pediatric and neonatal patients continue to emerge. The prolonged use of dexmedetomidine in very-low-birth-weight neonates has not been described in the literature.

CONCLUSIONS

Dexmedetomidine was an effective sedative and analgesic in a 24-week gestational age neonate treated for refractory agitation while on mechanical ventilation. Based on its documented efficacy for pain and sedation and its favorable adverse effect profile, dexmedetomidine warrants further study as first-line or adjunct therapy with narcotics for sedation in ventilated newborns.

The use of dexmedetomidine in critically ill children

OBJECTIVE

To describe the use of dexmedetomidine for sedating intubated children in a general medical/surgical pediatric intensive care unit (PICU).

DESIGN

Retrospective, observational study.

SETTING

Multidisciplinary PICU of a tertiary, university-affiliated children's hospital.

PATIENTS

All children receiving dexmedetomidine within the PICU during the period of August 2003 to August 2005.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

During the study period, 121 mechanically ventilated patients, median age 36 months (range 2 months to 21 years), who received dexmedetomidine infusions. The infusion was initiated and adjusted per our PICU protocol. The average dose was 0.55 microg/kg/hr (range 0.15-0.70 microg/kg/hr) and average length of use was 25.8 hours (range 20 minutes to 60 hours). During the dexmedetomidine infusion, the mean decrease in total benzodiazepine and opiate dose as compared with the 24 hours prior was 42% and 36%, respectively. Most patients were able to reduce their benzodiazepine and opiate dose by at least 20% with the dexmedetomidine infusion (70% and 73% of patients, respectively). After discontinuing dexmedetomidine, the average change in total benzodiazepine and opiate dose as compared with the 24 hours before infusion was an increase of 14% and 1.5%, respectively. Fewer patients were able to maintain at least a 20% reduction in benzodiazepine and opiate after cessation of dexmedetomidine compared with the 24 hours before initiation (38% and 40% of patients, respectively). Hypotension and/or bradycardia requiring clinical intervention occurred in 33 of 121 (27%) patients. Discontinuation secondary to clinical concern was necessary in 12 of 121 (10%) patients.

CONCLUSIONS

Our study suggests that many, although not all, mechanically ventilated children may be able to reduce their need for other sedation medications with the use of dexmedetomidine. However, the potential side effects of dexmedetomidine necessitates close hemodynamic monitoring with its use.

Clinical uses of dexmedetomidine in pediatric patients

Dexmedetomidine is being used off-label as an adjunctive agent for sedation and analgesia in pediatric patients in the critical care unit and for sedation during non-invasive procedures in radiology. It also has a potential role as part of anesthesia care to prevent emergence delirium and postanesthesia shivering. Dexmedetomidine is currently approved by the US FDA for sedation only in adults undergoing mechanical ventilation for <24 hours. Pediatric experiences in the literature are in the form of small studies and case reports. In patients sedated for mechanical ventilation and/or opioid/benzodiazepine withdrawal, the loading dose ranged from 0.5 to 1 microg/kg and was usually administered over 10 minutes, although not all patients received loading doses. This patient group also received a continuous infusion at rates ranging from 0.2 to 2 microg/kg/h, with higher rates used in burn patients and those with withdrawal following > or =24 hours of opioid/benzodiazepine infusion. The dexmedetomidine dosage used for anesthesia and sedation during non-invasive procedures, such as radiologic studies, ranged from a loading dose of 1-2 microg/kg followed by a continuous infusion at 0.5-1.14 microg/kg/h, with most patients spontaneously breathing. For invasive procedures, such as awake craniotomy or cardiac catheterization, dosage ranged from a loading dose of 0.15 to 1 microg/kg followed by a continuous infusion at 0.1-2 microg/kg/h. Adverse hemodynamic and respiratory effects were minimal; the agent was well tolerated in most patients. The efficacy of dexmedetomidine varied depending on the clinical situation: efficacy was greatest during non-invasive procedures, such as magnetic resonance imaging (MRI), and lowest during invasive procedures, such as cardiac catheterization. Dexmedetomidine may be useful in pediatric patients for sedation in a variety of clinical situations. The literature suggests potential use of dexmedetomidine as an adjunctive agent to other sedatives during mechanical ventilation and opioid/benzodiazepine withdrawal. In addition, because of its minimal respiratory effects, dexmedetomidine has also been used as a single agent for sedation during non-invasive procedures such as MRI. However, additional studies in pediatric patients are warranted to further evaluate its safety and efficacy in all age ranges.

Sensitive and specific liquid chromatography–tandem mass spectrometric method for the quantitation of dexmedetomidine in pediatric plasma

Dexmedetomidine (Dex) is a lipophilic imidazole derivative used primarily for the sedation and anxiolysis of adults in the intensive care setting. Dex is being used more frequently in the pediatric intensive care unit. This report describes a selective and highly sensitive assay for Dex in pediatric plasma employing liquid chromatography-tandem mass spectrometry (LC-MS/MS). Dex was extracted from 200 microL of plasma by solid-phase extraction (SPE). High performance liquid chromatography (HPLC) separation was conducted on an YMC ODS-AQ C(18) column with a flow rate of 0.3 mL/min using a mobile phase comprised of 5 mM ammonium acetate buffer/0.03% formic acid in the solvent mixture of methanol/acetonitrile/water (20:20:60, v/v/v). The intra-day precision (coefficient of variation, % CV) and accuracy for quality control samples, ranged from 1.04 to 6.84% and 90.2 to 100.8%, respectively. The inter-day precision and accuracy ranged from 4.08 to 5.37% and 92.7 to 98.6%, respectively. Stability studies showed that Dex was stable during both the assay procedure and storage. The overall recovery was 76.6-78.3% for Dex in plasma. The analytical method showed excellent sensitivity using a small sample volume (200 microL) with a lower limit of quantitation of 5 pg/mL. This method is robust and has been successfully employed in a pharmacokinetic study of Dex in infants postoperative from cardiac surgery.

Hemodynamic and respiratory changes following dexmedetomidine administration during general anesthesia: sevoflurane vs desflurane

BACKGROUND

The current study evaluates the hemodynamic and respiratory effects of dexmedetomidine (DEX) when administered to children anesthetized with sevoflurane (SEVO) or desflurane (DES).

METHODS

After tracheal intubation and spontaneous ventilation, DEX (0.5 microg x kg(-1)) was administered over 5 min. Heart rate (HR), systolic blood pressure (sBP), diastolic blood pressure (dBP), and endtidal carbon dioxide (P(E)CO(2)) were monitored and recorded prior to DEX (time 0) and again at 5, 10, and 15 min after DEX.

RESULTS

The cohort included 80 children (1-12 years of age) anesthetized with SEVO (n = 40) or DES (n = 40). The lowest HR from time 0 to time 15 was less in patients anesthetized with SEVO compared with DES (104 +/- 16 b x min(-1) in the SEVO/DEX group vs 120 +/- 17 b x min(-1) in the DES/DEX group, < 0.01). Although both sBP and dBP decreased following the administration of DEX to patients anesthetized with either SEVO or DES, there was no difference in sBP or dBP between the two groups. Likewise, no evidence was found for changes in the P(E)CO(2) during the study period.

CONCLUSIONS

The administration of DEX (0.5 microg x kg(-1)) results in a lower HR in patients anesthetized with SEVO compared with DES. No evidence was found for differences in sBP, dBP, or P(E)CO(2) during spontaneous ventilation with 1 MAC of SEVO vs DES.

Dexmedetomidine: applications in pediatric critical care and pediatric anesthesiology

OBJECTIVE

To provide a general descriptive account of the end-organ effects of dexmedetomidine and to provide an evidence-based review of the literature regarding its use in infants and children.

DATA SOURCE

A computerized bibliographic search of the literature regarding dexmedetomidine.

MAIN RESULTS

The end-organ effects of dexmedetomidine have been well studied in animal and adult human models. Adverse cardiovascular effects include occasional episodes of bradycardia with rare reports of sinus pause or cardiac arrest. Hypotension has also been reported as well as hypertension, the latter thought to be due to peripheral alpha2B agonism with peripheral vasoconstriction. Although dexmedetomidine has no direct effects on myocardial function, decreased cardiac output may result from changes in heart rate or increases in afterload. There are somewhat conflicting reports in the literature regarding its effects on ventilatory function, with some studies (both human and animal) suggesting a mild degree of respiratory depression, decreased minute ventilation, and decreased response to CO2 challenge whereas others demonstrate no effect. The central nervous system effects include sedation and analgesia with prevention of recall and memory at higher doses. Dexmedetomidine may also provide some neuroprotective activity during periods of ischemia. Applications in infants and children have included sedation during mechanical ventilation, prevention of emergence agitation following general anesthesia, provision of procedural sedation, and the prevention of withdrawal following the prolonged administration of opioids and benzodiazepines.

CONCLUSIONS

The literature contains reports of the use of dexmedetomidine in approximately 800 pediatric patients. Given its favorable sedative and anxiolytic properties combined with its limited effects on hemodynamic and respiratory function, there is growing interest in and reports of its use in the pediatric population in various clinical scenarios.

Prospective evaluation of dexmedetomidine for noninvasive procedural sedation in children

OBJECTIVE

Children often require sedation for lengthy noninvasive procedures. Conventional agents such as chloral hydrate, benzodiazepines, or barbiturates have been associated with sedation failure, respiratory depression, and paradoxic agitation. Dexmedetomidine is a newer alpha(2)-adrenergic receptor agonist with sedative properties and minimal respiratory depression. We hypothesized that it would be an effective agent for these procedures.

DESIGN

Prospective case series.

SETTING

Tertiary care children's hospital.

PATIENTS

Children undergoing noninvasive procedures.

INTERVENTIONS

Children were sedated with dexmedetomidine given as a bolus of 0.5-1.0 microg/kg over 5-10 mins followed by an infusion of 0.5-1.0 microg/kg/hr. Vital signs, sedative effectiveness, recovery patterns, and complications were prospectively recorded.

MEASUREMENTS AND MAIN RESULTS

Forty-eight patients, aged 6.9 +/- 3.7 yrs, were sedated. Fifteen received dexmedetomidine after failing sedation with chloral hydrate and/or midazolam. Sedation was induced with 0.92 +/- 0.36 microg/kg over 10.3 +/- 4.7 mins and maintained with an infusion of 0.69 +/- 0.32 microg/kg/hr. All procedures were completed. Heart rate, blood pressure, and respiratory rate decreased (p < .0001) but remained within normal limits for age. End-tidal CO(2) exceeded 50 mm Hg in seven of 404 measurements (1.7%). Mean recovery time was 84 +/- 42 mins and was significantly longer in the rescue (117 +/- 41 mins) vs. primary (69 +/- 34 mins) group (p < .0001). No patient developed agitation during recovery.

CONCLUSIONS

Dexmedetomidine provided effective sedation in children undergoing noninvasive procedures and represents an alternative sedative choice for this population.

Rescue sedation with dexmedetomidine for diagnostic imaging: a preliminary report

BACKGROUND

Sedation is frequently required during noninvasive radiological imaging in children. Although commonly used agents such as chloral hydrate and midazolam are generally effective, failures may occur. The authors report their experience with dexmedetomidine for rescue sedation during magnetic resonance imaging.

METHODS

A retrospective chart review was undertaken.

RESULTS

The cohort included five patients ranging in age from 11 months to 16 years. Following the failure of other agents (chloral hydrate and/or midazolam), dexmedetomidine was administered as a loading dose of 0.3-1.0 microg x kg(-1) x min(-1) over 5-10 min followed by an infusion of 0.5-1.0 microg x kg(-1) x h(-1). The dexmedetomidine loading dose required to induce sedation was 0.78 +/- 0.42 microg x kg(-1) (range 0.3-1.2). The maintenance infusion rate was 0.57 +/- 0.06 microg x kg(-1) x h(-1) (range 0.48-0.69). The imaging procedures were completed without difficulty. No patient required additional bolus administrations or changes in the infusion rate. The duration of the dexmedetomidine infusion ranged from 30 to 50 min. The mean decrease in heart rate was 13.6 +/- 5.1 b x min(-1) (14.3 +/- 5.0% from baseline; P = 0.02), the mean decrease in systolic blood pressure was 26.4 +/- 15.2 mmHg (24.6 +/- 12.4% decrease from baseline; P = 0.004), and the mean decrease in respiratory rate was 1.4 +/- 1.5 min(-1) (7.5 +/- 7.9% decrease from baseline; P = NS). P(E)CO2 exceeded 6.5 kPa (50 mmHg) in one patient [maximum 6.6 kPa (51 mmHg)] with a maximum value of 6.0 +/- 0.4 kPa (46 +/- 3 mmHg). Oxygen saturation decreased from 98 +/- 1 to 95 +/- 1%; P = 0.001. No patient developed hypoxemia (oxygen saturation less than 90%). Mean time to recovery to baseline status was 112.5 +/- 50.6 min and time to discharge was 173.8 +/- 83.8 min.

CONCLUSIONS

Our preliminary experience suggests that dexmedetomidine may be an effective agent for procedural sedation during radiological imaging. Its potential application in this setting is discussed and other reports regarding its use in pediatric patients are reviewed.

Small dose of clonidine mixed with low-dose ropivacaine and fentanyl for epidural analgesia after total knee arthroplasty †

BACKGROUND

We studied whether a small dose of clonidine added to a ropivacaine-fentanyl mixture improves epidural analgesia without provoking side effects typically related to larger amounts of epidural clonidine.

METHODS

In this randomized, double-blinded study, patients (< or =85 yr, ASA I-III) underwent total knee arthroplasty (TKA) performed under spinal anaesthesia. After the operation, patients received an epidural infusion consisting of ropivacaine 2 mg ml(-1) and fentanyl 5 microg ml(-1) either without (Group RF, n=33) or with clonidine 2 microg ml(-1) (Group RFC, n=36). The infusion rate was adjusted within the range 3-7 ml h(-1).

RESULTS

Average rate of infusion was slightly smaller in Group RFC than in Group RF (mean (sd) 4.7 (0.72) vs 5.2 (0.8) ml h(-1), P=0.004). Compared with the RF group, patients in the RFC group required significantly less rescue pain medication, that is i.m. oxycodone (median (25th, 75th percentile) 0 (0, 7) vs 7 (0, 12) mg, P=0.027). Arterial pressure and heart rate were slightly lower in Group RFC throughout the study period (mean difference between the groups 5 mm Hg (P<0.002) and 3 min(-1) (P=0.12), respectively). The groups did not differ statistically with respect to nausea, motor block, and sedation.

CONCLUSIONS

The small amount of clonidine added to the low-dose ropivacaine-fentanyl mixture reduced the need for opioid rescue pain medication after TKA. Clonidine slightly decreased arterial pressure and heart rate without jeopardizing haemodynamics. Otherwise, the side effect profiles were comparable in both groups.