|
|
|
Indian Pediatr 2009;46: 761-763 |
 |
Sedation Challenges in the Pediatric ICU: Is
Dexmedetomidine the Solution? |
|
R Blaine Easley
Department of Anesthesiology and Critical Care Medicine,
Johns Hopkins Hospital, 600 North Wolfe Street, Blalock 941, Baltimore, MD
21287, USA. [email protected]
|
|
The pediatric intensive care unit (PICU)
poses unique pain and sedation management challenges. Treatment of pain
and anxiety in the PICU has historically been accomplished with opioids
and benzodiazepines. More recently, drug therapy has been complemented
with sedation scales and non-pharmacologic treatment measures, such as
parental presence at the bedside and psychologic interventions (i.e.
distraction, redirection, etc.), to help create more effective sedation
practices and less-threatening PICU environments(1). Even with these
measures, critically ill children often need prolonged sedation to
facilitate respiratory manage-ment, treatment of multi-organ system
dysfunction and/or performance of invasive procedures. The consequence is
escalating dosages, physiologic tolerance and subsequent development of
withdrawal when these agents are discontinued(2). These sedation
challenges drive many PICU clinicians to seek alternative pharmacologic
agents (even volatile anesthesia) to provide comfort to critically ill
children(1).
Dexmedetomidine (DEX) is a highly selective
a2-adrenergic
agonist with sedative, anxiolytic, and analgesic properties. DEX provides
effective sedation without the respiratory depression often seen with
other agents and exhibits a synergistic sedative and analgesic effect when
given in conjunction with benzodiazepines and opioid analgesics(3). The
most common adverse effects associated with DEX include hypotension,
brady-cardia, and even hypertension, which are usually related to rate of
administration and dosage. DEX is currently approved for use in critically
ill, mechanically ventilated and intubated adults as a continuous infusion
for <24 hours. To date, the drug is not approved for use in children or
for prolonged infusion. Studies evaluating the pharmacology and
pharmacodyamics of DEX in pediatric patients are limited in scope and
number, and yet there is a growing international experience with the use
of DEX for children undergoing procedural and ICU-based sedation for acute
and prolonged periods of time(4,5).
The study by Reiter, et al.(6), in this issue of
Indian Pediatrics, describes their experience with the usage of DEX
for prolonged sedation in critically ill children. By retrospectively
reviewing the charts of children receiving DEX, they characterized
indications, patient demographics, and observed adverse events. DEX was
initiated in 41% of children (n=12/29) to facilitate extubation and
resulted in a duration of DEX treatment
³32
hours (n=29). Only 33% (n=10) received a loading dose of DEX
prior to initiating a continuous infusion. Though there were no adverse
events reported in their study population, there was a transient and
statistically significant reduction in heart rate (±13 beats per min)
within the first 24 hours of therapy, independent of a DEX loading dose,
and no interventions were required. An important finding of this study was
the clinician’s expectation that DEX would help facilitate extubation, but
instead DEX treatment was associated with an increase in the extubation
failure rate from 6% to 30%. The authors correctly discuss the potential
confounding issues that may have contributed to this finding including
lack of their clinical experience with how DEX might affect their "extubation
readiness" evaluation. This contrasts with Carroll, et al.(5), who
found that DEX facilitated extubation in mechanically ventilated children.
One significant difference between these studies was the duration of DEX
therapy (mean of 32 vs. 23 hours, respectively). Future studies
will be required to specifically address the effect of DEX infusion
duration on extubation success.
Subtle clinical differences in DEX sedation may
necessitate adaptation of sedation scales when DEX is used. The current
study(6) demonstrated no difference between pre-DEX infusion and during-DEX
infusion sedation scores. This finding may represent a bias in the limited
number of children receiving sedation scores, lack of a sedation
assessment protocol or even a lack of scale validity with DEX sedation. In
general, sedation scales lacking a provocative stimulus (touch, tracheal
suctioning, etc) have been shown to over-estimate the sedation level of
the patient when left to simple observation(7). Attempts to use DEX for
procedures that are inherently stimulating (such as endocscopy or cardiac
catheterization) have proven that DEX as the sole agent is inadequate to
maintain an effective level of sedation and analgesia when a painful or
unpleasant stimulus is present(8).
Though DEX initation, maintenance and discontinuation
in the current study were at the discretion of the bedside clinicians,
there were no observed adverse events (such as hemodynamic or withdrawal).
Notably, 93% (n=13) patients receiving DEX infusions >72 hours had
the dose tapered over a 1 to 4 day period. Such a slow taper may have
eliminated a possible discontinuation syndrome (hypertension and
agitation)(9). This observed absence of adverse events with
discontinuation of prolonged DEX infusions is consistent with other
reports(3-5).
The increased usage of DEX in critically ill children
is the direct result of the bedside challenges many PICU clinicians face
in sedation management. Available studies of DEX pharmacology in children
have provided conflicting information, which is highlighted by two recent
pharmacology studies, one suggesting infants need a higher dosage and the
other saying current dosing ranges are adequate(9,10). Prospective studies
of stable infants and children receiving bolus and maintenance DEX
infusions are needed to resolve this issue.
The findings of the Reiter study help us understand the
potential safety, efficacy and limitations of DEX sedation in children. At
this time, DEX is not a single-drug solution to the complicated problem of
pediatric sedation, but it appears to have a potential complementary role
in the challenging task of sedating critically ill children in the ICU.
Funding: None.
Competing interests: I am a member of the
National Scientific Advisory Board for Hospira Inc, USA, to address
dexmedetomidine usage in children. I have neither honoraria nor financial
reimbursement to disclose.
References
1. Yaster M, Easley RB, Brady KM. Pain and sedation
management in the critically ill child. In: Nichols DG, editor.
Rogers’s Textbook of Pedia-tric Intensive Care. 4 thEdition.
Philadelphia, PA: Lippincott, Williams & Wilkins; 2008.p.136-165.
2. Easley RB, Nichols DG. Withdrawal assessment in the
PICU: quantifying a morbidity of pain and sedation management in the
critically ill child. Crit Care Med 2008; 36: 2479-2480.
3. Tobias JD. Dexmedetomidine: applications in
pediatric critical care and pediatric anesthesiology. Pediatr Crit Care
Med 2007; 8: 115-131.
4. Walker J, Maccallum M, Fischer C, Kopcha R, Saylors
R, McCall J. Sedation using dexmedeto-midine in pediatric burn patients. J
Burn Care Res 2006; 27: 206-210.
5. Carroll CL, Krieger D, Campbell M, Fisher DG, Comeau
LL, Zucker AR. Use of dexmedetomidine for sedation of children
hospitalized in the intensive care unit. J Hosp Med 2008; 3: 142-147.
6. Reiter PD, Pietras M, Dobyns EL. Prolonged
dexmedetomidine infusions in critically ill infants and children. Indian
Pediatr 2009; 46: 767-773.
7. Curley MA, Harris SK, Fraser KA, Johnson RA, Arnold
JH. State Behavioral Scale: a sedation assessment instrument for infants
and young children supported on mechanical ventilation. Pediatr Crit Care
Med 2006; 7: 107-114.
8. Mester R, Easley RB, Brady KM, Chilson K, Tobias JD.
Monitored anesthesia care with a combination of ketamine and
dexmedetomidine during cardiac catheterization. Am J Therap 2008;
15: 24-30.
9. Weber MD, Thammasitboon S, Rosen DA. Acute
discontinuation syndrome from dexmedetomidine after protracted use in a
pediatric patient. Paediatr Anaesth 2008; 18: 87-88.
10. Vilo S, Rautiainen P, Kaisti K, Aantaa R, Scheinin
M, Manner T, et al. Pharmacokinetics of intravenous dexmedetomidine
in children under 11 yr of age. Br J Anaesth 2008; 100: 697-700.
11. Potts AL, Warman GR, Anderson BJ. Dexmedetomidine
disposition in children: a population analysis. Paediatr Anaesth 2008; 18:
722-730.
|
|
|
 |
|
