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The Impact of Oral Premedication with Midazolam on Respiratory Function in Children

The Impact of Oral Premedication with Midazolam on Respiratory Function in Children. Anesth Analg 2009;108:1771–6. Background. Preoperative anxiety in children delirium on recovery postoperative behavioral disturbance

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The Impact of Oral Premedication with Midazolam on Respiratory Function in Children

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  1. The Impact of Oral Premedication with Midazolam onRespiratory Function in Children Anesth Analg 2009;108:1771–6

  2. Background • Preoperative anxiety in children • delirium on recovery • postoperative behavioral disturbance • midazolam is the most commonly used premedication drug in pediatric anesthesia • delivered by all routes of administration • a rapid onset • a short half-life compared benzodiazepines

  3. Background • Large doses in children • hypoxemia • critical event, especially in children with co-morbidities • FRC and other variables of ventilation with benzodiazepines in adults • muscle relaxant properties

  4. Background • No studies investigating • The extent of changes caused by midazolam on FRC in children • After a 0.3 mg/kg dose, which is commonly administered as a premedication

  5. Background • Aimed to investigate the effect of midazolam on respiratory function in spontaneously breathing children • Bef and aft premedication with midazolam

  6. Methods • 1:wide awake • 5:unarousable with deep stimulation 21 children baseline UMSS Midazolam 0.3 mg/kg LCI 20 min Respiratory function FRC pulse oximetry

  7. Measurement Apparatus • FRC and LCI • During tidal breathing with the child wearing a nose clip and breathing via a mouthpiece connected to an ultrasonic transit-time airflow meter(Exhalyzer D with ICU insert, Eco Medics, Duernten Switzerland) • Preformed in duplicate

  8. Results • 21 pats were recruited • 3 pats excluded • lack of cooperation during the measurements performed bef premed • 18 pats included (8 m, 10 f) • Age : 78.5 (36 –107) mo • Weight: 23.4 (12.6 –38.75) kg • Length: 118 (98 –132) cm

  9. Results

  10. Results

  11. Results • UMSS score of 1 (1–2) • successfully in the sitting position. • None showed any < 95% after the administration of midazolam.

  12. DISCUSSION • Apart from one child, there were no problems with regard to leakage around the mouthpiece as reflected by the stable inspiratory and expiratory TV difference before and after premedication • The small but statistically significant decrease in MV seen after premedication might be attributed to a reduction in anxiety rather than to sedation

  13. DISCUSSION • The lack of a placebo control is a limitation of the present study. • Premedication with placebo in an anxious child before surgery was considered unethical.

  14. DISCUSSION • The second assessment of FRC was made 20 min after the premedication with midazolam, • Approximately 2/3 of the children showed satisfactory anxiolysis. • Ensure optimal anxiolysis at induction of anesthesia. • The maximal clinical effect of midazolam may occur after 30 min, • The differences measured between the awake state and after premedication might potentially be underestimated.

  15. DISCUSSION • FRC is determined by the balance between the chest wall compliance, elastic lung recoil, active tension in the muscles of respiration, RR and TV. • During expiration, there is normally sufficient expiratory time to allow for emptying of the lungs to the elastic equilibrium volume (EEV) of the respiratory system.

  16. DISCUSSION • Children, especially young children, have a dynamic elevation of FRC above EEV • more rapid RR • limiting expiratory time • active “breaking” of expiratory flow by postinspiratory activation of inspiratory muscles. • Preanesthetic medications have both anxiolytic and muscle relaxant properties, and either action may result to a decrease in FRC.

  17. DISCUSSION • Although premedication with midazolam • significant reduction in TV and MV, • RR and expiratory times did not change , • The changes in FRC and LCI are unlikely to be explained simply by a reduction in the dynamic elevation of FRC above EEV.

  18. Summary • Premedication with midazolam led to significant decrease in FRC and alteration in respiratory mechanics. • A relatively small dose of midazolam • Shortly after its administration • Children had normal lungs

  19. Conclusion • Be aware that using midazolam in children at high risk of respiratory complications under anesthesia might lead to a significant decrease in respiratory function.

  20. Thank You

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