Continuous clonidine infusion: an alternative for children on mechanical ventilation

OBJECTIVE

This study aimed to assess the clonidine infusion rate in the first 6 h, as maintenance dose (first 24 h), and in the pre-extubation period (last 24 h), as well as the cumulative dose of other sedatives and the hemodynamic response.

METHODS

This is a retrospective cohort study.

RESULTS

Children up to the age of 2 years who were admitted to the pediatric intensive care unit of a tertiary referral hospital in the south region of Brazil, between January 2017 and December 2018, were submitted to mechanical ventilation, and received continuous clonidine infusions were included in the study. The initial, maintenance, and pre-extubation doses of clonidine; the vasoactive-inotropic score; heart rate; and systolic and diastolic blood pressure of the study participants were assessed. A total of 66 patients with a median age of 4 months who were receiving clonidine infusions were included. The main indications for mechanical ventilation were acute viral bronchiolitis (56%) and pneumonia associated with acute respiratory distress syndrome (15%). The median of clonidine infusion in the first 6 h (66 patients) was 0.53 μg/kg/h (IQR 0.49-0.88), followed by 0.85 μg/kg/h (IQR 0.53-1.03) during maintenance (57 patients) and 0.63 μg/kg/h (IQR 0.54-1.01) during extubation period (42 patients) (p=0.03). No differences were observed in the doses regarding the indication for mechanical ventilation. Clonidine infusion was not associated with hemodynamic changes and showed no differences when associated with adjuvants.

CONCLUSION

Clonidine demonstrated to be a well-tolerated sedation option in pediatric patients submitted to mechanical ventilation, without relevant influence in hemodynamic variables.

Bioavailability of Orally Administered Drugs in Critically Ill Patients

Critically ill patients managed in the Intensive Care Unit (ICU) suffer from several pathophysiological alterations due to critical illness resulting in potential changes in the pharmacokinetics of drugs including systemic absorption. Nevertheless, these patients are still given some medications in unadjusted doses thereby putting the patients at a risk for therapy failure. The objective for this study was to summarize the available evidence regarding oral drug absorption in the ICU. A literature search of the databases MEDLINE, EMBASE, and PubMed was conducted on (February 24, 2020). Articles discussing the rate and/or extent of orally administered drugs in critically ill patients were included. A total of 58 studies were found: 17 interventional studies, 33 observational studies (30 prospective, 3 retrospective) and 8 case reports. A total of 43 articles reported altered drug absorption in critically ill patients suggesting the need for alternative measures to facilitate treatment success. The absorption of orally administered drugs may be altered in critically ill patients. Measures for altered drug absorption in critically ill patients were suggested such as holding tube feeding before and after medication administration, increasing doses of orally administrated drugs and using alternate routes of administration.

Safety of clonidine used for long-term sedation in paediatric intensive care: A systematic review

AIM

Although not approved, the α-adrenoceptor agonist clonidine is considered an option for long-term sedation protocols in paediatric intensive care. We reviewed adverse effects of clonidine occurring in this indication.

METHODS

Relevant literature was systematically identified from PubMed and Embase. We included interventional and observational studies on paediatric patients admitted to intensive care units and systemically long-term sedated with clonidine-containing regimes. In duplicates, we conducted standardised and independent full-text assessment and extraction of safety data.

RESULTS

Data from 11 studies with 909 patients were analysed. The studies were heterogeneous regarding patient characteristics (age groups, comorbidity, or comedication) and sedation regimes (dosage, route, duration, or concomitant sedatives). Just four randomised controlled trials (RCTs) and one observational study had comparison groups, using placebo or midazolam. For safety outcomes, our validity evaluation showed low risk of bias only in three studies. All studies focused on haemodynamic problems, particularly bradycardia and hypotension. Observed incidences or subsequent interventions never caused concerns. However, only two RCTs allowed meaningful comparisons with control groups. Odds ratios showed no significant difference between the groups, but small sample sizes (50 and 125 patients) must be considered; pooled analyses were not reasonable.

CONCLUSION

All evaluated studies concluded that the use of clonidine in paediatric intensive care units is safe. However, a valid characterisation of the safety profile remains challenging due to limited, biased and heterogeneous data and missing investigation of long-term effects. This evaluation demonstrates the lack of data, which prevents reliable conclusions on the safety of clonidine for long-term sedation in critically ill children. For an evidence-based use, further studies are needed.

The Impact of a Clonidine Transition Protocol on Dexmedetomidine Withdrawal in Critically Ill Pediatric Patients

OBJECTIVES

This study describes our experience with a clonidine transition protocol to prevent dexmedetomidine (DEX) withdrawal in critically ill pediatric patients.

METHODS

Retrospective review of electronic medical records of patients in the pediatric intensive care unit of a single tertiary children's hospital. All patients up to 19 years of age, who received concomitant DEX infusion and enteral clonidine between June 1, 2016, and May 31, 2018, were included.

RESULTS

Two of 24 encounters had DEX restarted for withdrawal (8.3%). Five of 14 encounters who were transitioned to clonidine 2 mcg/kg every 6 hours required an increased dose, and 1 of 10 encounters transitioned to clonidine 4 mcg/kg every 6 hours required an increased dose (36% vs 10%, p = 0.21). For encounters with clonidine dose increases, 5 of 6 had improvements in Withdrawal Assessment Tool-1 (WAT-1) scores. Of these 5 encounters, 4 had decreasing or stable opioid and sedative requirements and 1 was transitioned to methadone. No encounters required discontinuation of clonidine owing to adverse events. Two of 24 encounters met our safety endpoint. One received a fluid bolus during the clonidine transition with no change in clonidine dosing, while the other had clonidine dose decreased for asymptomatic bradycardia.

CONCLUSIONS

The 24 encounters in our retrospective study add to the limited literature available to describe dosing, initiation time, and duration of clonidine to prevent withdrawal from DEX in critically ill pediatric patients. Further research is needed to clarify the optimal dosing and duration of clonidine to prevent DEX withdrawal in pediatric patients.

Hemodynamic Tolerance to IV Clonidine Infusion in the PICU

OBJECTIVES

Clonidine is an antihypertensive drug used for analgosedation in the PICU. Lack of reliable data on its hemodynamic tolerance limits its use. This study explores the hemodynamic tolerance of IV clonidine infusion in a broad population of children with high severity of disease.

DESIGN

Retrospective analysis of prospectively collected data.

SETTING

A tertiary and quaternary referral PICU.

PATIENTS

Critically ill children age 0-18 years old who received an IV clonidine infusion for analgosedation of at least 1 hour.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary endpoints were the prevalences of bradycardia and hypotension. Secondary endpoints were changes in heart rate, blood pressure, Vasoactive-Inotropic Score, COMFORT Behavior score (a sedation scoring scale), and body temperature during the infusion. The association of bradycardia with other hemodynamic variables was explored, as well as potential risk factors for severe bradycardia. One-hundred eighty-six children (median age, 12.9 mo [interquartile range, 3.5-60.6 mo]) receiving a maximum median clonidine infusion of 0.7 µg/kg/hr (interquartile range, 0.3-1.5) were included. Severe bradycardia and systolic hypotension occurred in 72 patients (40.2%) and 105 patients (58%), respectively. Clonidine-associated bradycardia was hemodynamically well tolerated, as it was not related with hypotension and the need for vasoactive drugs decreased in parallel with a sedation score guided clonidine infusion rate increase. Younger age was the only identified risk factor for clonidine-associated bradycardia.

CONCLUSIONS

Although administration of clonidine is often associated with bradycardia and hypotension, these complications do not seem clinically significant in a mixed PICU population with a high degree of disease severity. Clonidine may have a vasoactive-inotropic sparing effect.

Population pharmacokinetics of intravenous clonidine for sedation during paediatric extracorporeal membrane oxygenation and continuous venovenous hemofiltration

AIMS

Clonidine is used for sedation in the paediatric intensive care unit. Extracorporeal membrane oxygenation (ECMO) provides temporary support if respiratory and cardiac function is threatened. ECMO influences the pharmacokinetics of drugs. Clonidine during paediatric ECMO cannot be effectively titrated as PK data are lacking. The aim of this study is to describe clonidine PK in a particular ECMO system and propose dosing guidelines for children on this particular ECMO circuit.

METHODS

All children below the age of 18 years who received clonidine during ECMO were eligible. The pharmacokinetic analysis was conducted by nonlinear mixed effect modelling, which enables to establish the separate influences of determinants on drug blood level and to provide individualized dosing.

RESULTS

Twenty-two patients, median age 1 month (IQR 6.4) and weight at inclusion 4 kg (IQR 3.1) were included of whom 90% in addition to ECMO received pre-emptive continuous venovenous hemofiltration to optimize fluid balance. The clonidine clearance rate was two-fold that measured in patients not on ECMO. Clearance increased steeply with postnatal age: at days 6, 8 and 10, respectively 30%, 50% and 70% of the adult clearance rate was reached. The use of diuretics was associated with a lower clearance. The volume of distribution increased by 55% during ECMO support.

CONCLUSION

Our findings suggest that a higher dose of clonidine may be needed during ECMO. The PK parameters on ECMO and the dosing guidelines proposed hold the potential to improve sedation practices on ECMO but need to be repeated with different ECMO systems.

Clonidine for Sedation and Analgesia and Withdrawal in Critically Ill Infants and Children

The need for sedation and analgesia and treatment of iatrogenic drug withdrawal is common in critically ill children. First-line therapy typically includes opioid agonists. However, clonidine, a central α₂ agonist, has been suggested as a treatment option for sedation and analgesia and iatrogenic drug withdrawal. Therefore, we conducted a literature search to identify articles evaluating the use of enteral (PO) and transdermal clonidine in critically ill infants and children for sedation and analgesia and treatment of iatrogenic drug withdrawal. The literature search was limited to English-language articles in Medline (1946-May 2016), Embase (1988-May 2016), and International Pharmaceutical Abstracts (1970-May 2016). Reference citations from relevant articles were also reviewed. Ten case reports and studies, representing a total of 114 children receiving clonidine, were included. Fifty patients (43.9%) received clonidine for sedation and analgesia while mechanically ventilated, and 33 (29.0%) received clonidine for treatment or prevention of drug withdrawal. The remaining 31 patients (27.1%) were included in a pharmacokinetic study that did not evaluate clinical outcomes. Seventy-nine patients (69.3%) received PO clonidine, with a dosage range of 2-15 µg/kg/day divided every 6-8 hours. Thirty-five patients (30.7%) received transdermal clonidine, with a dosage range of 2.3-20 µg/kg/day. Whole, cut, and occluded transdermal patches were used in the reports. Patients receiving cut patches had more variable and significantly higher serum clonidine concentrations than those receiving whole patches. Only three studies reported that the PO clonidine dose was tapered at the end of therapy; however, no report specifically described the process. The two most common adverse events reported with PO and transdermal clonidine were bradycardia and hypotension. PO and transdermal clonidine have a potential role for sedation and analgesia and drug withdrawal in critically ill infants and children. The use of cut transdermal patches should be avoided. Future prospective studies are needed to further define clonidine's role as adjunct therapy or monotherapy.

Pharmacological sedation management in the paediatric intensive care unit

Objective

This review addresses sedation management on paediatric intensive care units and possible gaps in the knowledge of optimal sedation strategies. We present an overview of the commonly used sedatives and their pharmacokinetic and pharmacodynamic considerations in children, as well as the ongoing studies in this field. Also, sedation guidelines and current sedation strategies and assessment methods are addressed.

Key findings

This review shows that evidence and pharmacokinetic data are scarce, but fortunately, there is an active research scene with promising new PK and PD data of sedatives in children using new study designs with application of advanced laboratory methods and modelling. The lack of evidence is increasingly being recognized by authorities and legislative offices such as the US Food and Drug Administration (FDA) and European Medicines Agency (EMA).

Conclusion

The population in question is very heterogeneous and this overview can aid clinicians and researchers in moving from practice-based sedation management towards more evidence- or model-based practice. Still, paediatric sedation management can be improved in other ways than pharmacology only, so future research should aim on sedation assessment and implementation strategies of protocolized sedation as well.

Clonidine as a First-Line Sedative Agent After Neonatal Cardiac Surgery: Retrospective Cohort Study

OBJECTIVES

To determine the cardiovascular tolerance of clonidine used as a first-line sedative after cardiac surgery in small infants.

DESIGN

Retrospective chart review.

SETTING

A tertiary and quaternary referral cardiac PICU.

PATIENTS

All infants younger than 2 months who received a clonidine infusion for sedation after cardiac surgery from October 2011 to July 2013.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Heart rate, blood pressure, central venous and left atrial pressure, vasoactive inotropic score, volume of fluid bolus, and lactate and central mixed venous saturation were assessed. Preinfusion values were compared with postinfusion values. Of 224 potentially eligible patients, only 23 infants met inclusion criteria, as most patients only received high doses of morphine and some received midazolam instead of clonidine. Clonidine administration was started at a median of 12 hours after surgery (Q1-Q3, 5-23), and infusion rate was 0.5-2 μg/kg/hr for a median duration of 30 hours (Q1-Q3, 12-54). Heart rate decreased (maximal mean decrease: 12% [149 beats/min (SD, 17) to 131 beats/min (SD, 17)]; p < 0.0001). Apart from a transient and limited drop in diastolic blood pressure of 13% (maximal mean decrease: from 42.8 mm Hg [SD, 5.9] to 37.1 mm Hg [SD, 4.0]; p = 0.018), all other cardiovascular variables were stable or improved. A contemporaneous cohort of patients who received midazolam, did so sooner after surgery, stayed longer in the PICU and showed less favorable hemodynamics.

CONCLUSIONS

IV clonidine as sedative added to morphine in selected patients seems hemodynamically safe. The observed decrease in heart rate and diastolic blood pressure seems of minimal clinical importance as all other hemodynamic variables remained stable or improved. The safety of clonidine given early after cardiac surgery as alternative to midazolam merits further study.