Transcript Bronchodilator premedication does not decrease respiratory

Bronchodilator premedication does not
decrease respiratory adverse events in
pediatric general anesthesia
CAN J ANESTH 2003 /50 : 3 / pp 277-284
Wariya sukhupragarn
• The association between a recent URI and respiratory adverse
events.
• Common challenge in pediatric anesthesia.
• Elective surgery may be cancelled because of recent URI,
although individual practice varies widely .
• URI may develop while awaiting rescheduled surgery.
• Children have an average of six URI per year.
Definition
• URI : 2 or more of the following symptoms ( sore throat,
sneeze, rhinorrhea, congestion, malaise, cough, fever,
hoarseness )
• active URI : peak symptoms within 7 preoperative days
• recent URI : within the preceding 6 weeks.
1.What is the research question ?
Does Bronchodilator premedication
decrease respiratory adverse events in
pediatric general anesthesia ?
2. What is the study type ?
• Block - randomized , age - stratified , double - blind controlled
trial.
– Randomization was stratified according to intubate or not.
– And stratified according to age ( 0-1 , 1-2 , 2-5 , and >5 yrold )
– observer : blind-study medication , URI status
3.What are the outcome factors
and how are they measured ?
• Respiratory adverse events
– Bronchospasm
– Laryngospasm
– hemoglobin desaturation
• Capnography
- Cough
- Wheez
- Stridor
SpO2
– preoperative
- duration of desat. <95% ,<85%
– after onset of bronchodilator
The ordinal scale for stridor and
laryngospasm
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•
•
•
•
1
2
3
4
5
=
=
=
=
=
stridor ( inspiratory high - pitched monophasic ) only
1 + desaturation < 93 %
2 + required CPAP
3 + duration > 30 sec despite CPAP
required muscle relaxant
4. What are the study foctors
and how are they measured ?
• Bronchodilators
• Phase 1 ( Baltimore )
– ipratropium ( 500 ug or 250 ug if < 2 yr - old ) in 2.5 ml NSS.
– NSS.
– No inhaled premedication.
• Phase 2 ( Seattle )
– Albuteral 2.5 mg (0.5 ml) in 2.5 ml NSS
– O2 8 l/m via empty nebulizer
5.What important potential
confounders are considered ?
• Exclusion criteria
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–
–
–
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diagnosis of asthma or other chronic lung disease ( by physician )
Hx of prematurity ( GA < 36 wks ) in infants age < 12 months.
Ronchi or coarse rales evident preoperative.
Fever > 38 C axillary
Sx of the airway, cranium, chest, or upper abdomen ( blood in the
airway, altered mental status, chest wall splinting )
• Rectal acetaminophen, regional or local anesthesia
provided analgesia.
• Avoid atropine and opioid administration were
avoided in all patients.
• Vecuronium was the relaxant used when intubation
was performed
Record
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•
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•
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Procedure
duration of Sx
level of training of the person managing the airway
type of airway management ( mask , laryngeal mask , ETT )
use of regional anesthesia
duration of PACU stay
unplanned admission to hospital
deviation from protocol
6.What are the sampling frame
and sampling method ?
• Inclusion criteria
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scheduled out-patient elective surgical procedures < 3 hrs.
age 2 months - 18 yr.
ASA physical status I or II.
Planned mask induction and halothane maintenance.
• 135 children were enrolled without knowledge of
their Hx of recent or active URI.
7. How were the subjects
assigned to groups ?
• A computer-generated random sequence assigned patients to
groups in blocks of nine , and randomization code remained
unbroken until completion of each phase of the study.
• Randomization was stratified according to intention to intubate or
not
• and according to age ( 0-1, 1-2, 2-5, and >5 yr old )
8. Are statistical tests considered ?
• Continuous variables : Wilcoxon rank sum test ( WRS )
• Proportions : Fisher’s exact test (FE) or Pearson chi-square .
9. Are the results clinically/
socially significant ?
• Table I : no demographic differences
• Table II : Placebo nebulized saline increase cough.
– Administration of bronchodilators did not affect any
out come when compared to placebo or nonintervention.
• Analyzing the entire study population, no
association between either recent URI or active URI
and desaturation, cough, stridor, laryngospasm or
wheeze ( all P > 0.05 )
• Utilizing an alpha of 0.05 and power of 80%, analysis
– stridor-laryngospasm needed 90 patients / group
– desaturation
440 patients / group
– laryngospasm
9,500 patients / group
• Table III support a lower adverse event rate for patients
managed by Mask vs either LMA or ETT
• Table IV intubation was associated with significantly
longer desaturation < 95% than with the LMA
• Table V high inter-rater reliability of end-points.
10. What conclusions did the
authors reach about the study
question ?
• The size of study required to show an outcome difference
suggest that any beneficial effect of bronchodilators is
clinically trivial.
• Possible explanation for the lack of bronchodilator effect
in this study
• 1. The beneficial effect of the bronchodilator may be
lost among the multitude of other factor contributing to
emergence adverse events.
• 2. Bronchoconstriction may not be a factor in
emergence adverse events, since wheezing was rarely
observed.
• 3. If the cholinergic receptor is damaged by virus, an
anticholinergic drug may not be able to exert its effect on
a damaged receptor.
• 4. The study drug may not have been delivered
adequately to its target.
• There are several limitations in this study
– The results should not be applied to the common pediatric
operation of tonsillectomy without further data.
– The study bear repeating in patients at higher risk for
complication before dismissing the role of preoperative
bronchodilator therapy in this setting.
– No standardize airway Mx or anesthetic technique.
•
Clinicians can safely proceed with Sx despite URI in a
selected population.
– Afebrile ASA I-II patients with no lung disease or lung
findings, having elective non-cavitary, non-airway
surgery less than 3 hours in length.
– Further research is needed to define children with URI
symptoms who are at low risk for perioperative
respiratory complications.