SEDATION AND ANALGESIA AFTER PEDIATRIC CARDIAC SURGERY By Mai Mohsen Abdel Aziz, MD
Transcript
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By Mai Mohsen Abdel Aziz, MD
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In recent years, the importance of appropriate intraoperative
anesthesia and analgesia during cardiac surgery has become
recognized as an important factor in postoperative recovery However
little attention has been focused on postoperative sedation and
analgesia in the pediatric ICU
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Separation from parents Invasive procedures Disruption of usual
day-night cycle Unfamiliar people and machines Physiological causes
of agitation have to be excluded ; - Hypoxemia - Hypercapnia -
Cerebral hypoperfusion due to reduced COP
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Inadequate analgesia and postsurgical stress response
metabolic, humoral, and hemodynamic response following injury or
surgery. Neuroendocrine cascade leads to increased oxygen
consumption, increased carbon dioxide production, generalized
catabolic state with a negative nitrogen balance. Recent studies
have concluded that inadequate pain control causes long term
dysregulation of nociceptive mechanisms which may change behavior
and responses to future pain stimuli.
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Agent to be used Mode of administration Route of delivery
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Rapid onset Predictable duration of activity Effects dissipate
rapidly when agent discontinued Easy to titrate by continuous
infusion Limited effects on cardiorespiratory function Effects and
duration not altered by renal or hepatic disease Wide therapeutic
index No interference with effect or metabolism by other drugs
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Benzodiazepines Opioids Ketamine Propofol Chloral hydrate
Phenothiazines Barbiturates NSAID Acetaminophen -2 agonists Most
drugs can have deleterious effects on cardiorespiratory function
therefore close monitoring of patients cardiorespiratory status in
accordance with guidelines of the American Academy of
Pediatrics
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Sedatives and analgesics should not be administered strictly on
a per Kg basis Dosage recommendations are meant as guidelines for
starting doses Actual amount administered should be titrated to
achieve the desired level of sedation or analgesia Significant
interpatient variability in infusion requirements
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A broad term that facilitate several goals; Unconsciousness or
reduction in conscious level Reduced awareness Loss of explicit and
implicit memory Compliance with the need to lie attached to
monitors and invasive lines Prevention of distress
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MinimalModerateDeep General DescriptionAnxiolysisConsciousDeep
sleep Responsiveness Airway Ventilation Cardiovascular appropriate
Unaffected Purposeful to light stimulation No intervention Adequate
Maintained Purposeful to pain stimulation () Intervention ()
Inadequate () Maintained SEDATION LEVELS Risk of Adverse Event No
Sedation Mild Sedation Moderate Sedation Continuous monitoring is
mandatory; SpO2 ECG RR BP +/- etCO2
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Comfort scale Range (8-40) Excessive (8-16) Adequate (17-26)
Insufficient (27-40)
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1- All sedative drugs suppress the CNS 2- Respiratory
depression: the most significant adverse effect following sedative
drug administration a. Impaired airway control - the single most
serious adverse event b. Hypoventilation 3- Depth of sedation is a
continuum mild sedation general anesthesia 4-The greater depth of
sedation the greater risk
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Pharyngeal Segment Nasal Segment Tracheal Segment THE UPPER
AIRWAY Pharyngeal collapse during sedation inhibition IX X P(-)
P(O)
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pCO 2 Minute ventilation (l/min) VENTILATION HYPOVENTILATION
DURING SEDATION sedation
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First line agents hypnosis NO analgesia action in the limbic
anxiolysis system via inhibitory GABA antegrade amnesia Abstinence
syndrome anticonvulsant effect after prolonged use May produce
hypotension with decrease in COP>20% in postcardiac surgical
patients Decreased central sympathetic output which may decrease
systemic vascular resistance
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Sedating, variable amnesia, anxiolytic Irritating to veins,
pain in injection(propylen glycol) Highly lipid soluble, rapid
onset Multiple active metabolites Advantage for prolonged sedation
Disadvantage for rapid arousal Not recommended for continuous
infusion Half-life 12-24 hrs Hepatic metabolism
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Improved amnesia No active metabolites Half life 4-12 hours
Metabolized by glucuronyl transferase Less influence from other
drugs Better preserved in patients with liver disease
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Rapid onset Rapid metabolism Good amnesia Water soluble, no
pain with injection Half life 2 -4 hours Hepatic metabolism with
renal excretion Active hydroxy-metabolite may accumulate Other
routes of administration Oral,Nasal,Rectal,Sublingual Reports of
dystonia and choreoathetosis post infusion, greater risk in
neonates Heparin decreases protein binding, increases free drug
Dosing ranging from 0.05-0.2 mg/kg/hr
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RESPIRATORY DEPRESSION Less than narcotics, but potentiated
with narcotics Dose related Reversal Flumazenil - benzodiazepine
receptor antagonist Choreoathetoid movement disorder Tolerance
Dependence Withdrawal carefully and slowly if administered >
7-10 days Signs of withdrawal - tremor, tachycardia, hypertension,
Rapid withdrawal may promote seizures
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First line analgesia sedation no amnesia delayed gastric
emptying decreased intestinal peristalsis urinary retention
Commonly used narcotics: Morphine Fentanyl Methadone
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ROUTE OF ADMINISTRATION IV Oral Transmucosal Transdermal MODE
OF ADMINISTRATION Intermittent/on demand (as necessary) Fixed
interval Continuous infusion PCA
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Intravenous bolus administration Common though antiquated PRN -
as needed Half-life of drug determines interval Disadvantage of
pain breakthrough
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Utilized when prolonged analgesia and sedation needed Better
analgesia, initial accurate bolus important Need for dedicated IV
site
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Patient controlled analgesia Allows patient to administer a
preset amount of narcotic at preselected intervals Improved
analgesia with decreased narcotic use Option to include low basal
rate Nurse controlled analgesia Eliminates delay Allows delivery
via a closed system
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Gold standard hepatic metabolism depresses respiration
depresses rate over tidal volume histamine mediated hypotension esp
in hypovolemic Can block compensatory catecholamine effect
Prolonged clearance in neonates
Synthetic opiate, 100 x morphine rapid onset highly lipophilic
hepatic metabolism minimal hemodynamic effect chest wall rigidity
Short distribution t 1/2, long elimination t 1/2, Blunts pulmonary
vascular responses
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IV intermittent dosing 1-2 mcg/kg q 1-2 hrs IV continuous
dosing 1-2 mcg/kg/hr Transdermal delivery system available Not
recommended in children less than 12 yrs 25,50,75,100 mcg/hr 25
mcg/hr is equivalent to 15 mg morphine in a 24 hr period
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Potency equivalent to morphine Half life 12-24 hrs Prolonged
duration of action abolishes the need for continuous infusion
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RESPIRATORY DEPRESSION Reversal - Nalaxone (Narcan) Full
reversal 0.1 mg/kg Half life is less than narcotics IV,IM,Sub Q,
ETT Abrupt reversal may result in nausea, vomiting, sweating,
tachycardia, increased BP, and tremors Pruritis Individual
variability and susceptibility, alleviated by Benadryl
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Tolerance Need for increase in dose to achieve the same effect
Generally develops after 2-3 days of frequent/continuous use
Greater with fentanyl Treated by increasing the dose as needed
DEPENDENCE Physiological state leading to abstinence syndrome on
withdrawal of the drug, rare Generally develops after 7-10 days of
sustained use Symptoms include: mydriasis, tachycardia, goose
bumps, muscle jerks, vomiting, diarrhea, seizures, fever,
hypertension Treated with gradual withdrawal of the drug
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Dissociative IV anesthetic good amnesia analgesia water and
lipid soluble crosses BBB
Pain with injection/infusion site Improved with use of 1%
lidocaine Neurologic sequela Opisthotonic posturing Myoclonic
movements Metabolic acidosis reported with use > 24 hrs
Contraindicated for long term use Dosing 1 - 3 mg/kg induction 20 -
100 mcg/kg/min Increase infusion rate 5-10 mcg/kg/min increments of
5 - 10 minutes
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Sedative hypnotic agent Metabolized in the liver to its active
form, trichlorethanol Half life 8-12 hours Oral or rectal
administration Onset of action delayed Not to exceed 100 mg/kg/day
- i.e.: 25mg/kg/q 6 hrs Caution in children < 3 months or with
hepatic dysfunction
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Sedative Respiratory depression dose dependent Negative
inotropic effects/vasodilation - decreased cardiac output Decreased
cerebral O 2 consumption CBF ICP Anticonvulsant, Useful in patients
with increased ICP Alkaline solution, often incompatible with TPN
or meds.
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Phenothiazine Thorazine Butyrophenones Droperidol Haloperidol
Common in adult ICU, uncommon in PICU Side effects hypotension due
to alpha blockade and extrapyramidal effects May be useful in the
difficult to sedate child
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Clonidine Selectivity: 2 : 1 250:1 t 1/2 10 hrs
Antihypertensive PO, patch, epidural In opioid withdrawal
Dexmedetomidine Selectivity: 2 : 1 1620:1 t 1/2 2 hrs Eliminated by
liver/kidney Sedative Only available in IV form Precedex 200
ug/vial others : apraclonidine, detomidine, medetomidine
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Dose dependent sedation, patients are easily arousable
Anxiolysis Analgesia Reduces shivering Minimal respiratory
depression Known action Hyperpolarization of LC neurons 2
A-receptor subtype Reversible (atipamezole)
Continuous intravenous infusions of morphine or fentanyl are
recommended for the relief of severe pain. Non-steroidal
anti-inflammatory drugs or paracetamol may be used as adjuncts to
opioids in certain patients.
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Pain assessment should be performed regularly by using a scale
appropriate to the age of the patient and routinely documented. The
level of sedation should be regularly assessed and documented using
a validated scoring system such as the COMFORT scale. Midazolam is
the recommended agent for the majority of critically ill children
requiring intravenous sedation and preferably by continuous
infusion. Clonidine given by continuous intravenous infusion may be
used as an alternative sedative agent to midazolam. Propofol should
not be used to provide continuous sedation in critically ill
children.