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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 • • • • • 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 – – – – – 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 • • • • • • • • 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 – – – – 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.