Basic Pediatric Anesthesia

1. �Basic� Pediatric Anesthesia

2. Airway Tongue relatively large compared to remainder of airway, along with relatively small jaw Glottis in an �anterior�, cephalad displacement Glottis located at C2 in infant vs. C4-5 in adult, with cricoid cartilage located at C4 in the child and C6-7 in adult Oblique angle of vocal cords, slanting downward anteriorly Epiglottis shape is larger, longer and curved (�omega-shaped�), creating floppy characteristics Narrowest segment at the cricoid, creating an inverse cone-shape of the airway

5. Glottic Opening in Relationship to Cervical Vertebra

6. Adult Larynx Adult Larynx xerogram and schematic � relatively thin, broad epiglottis, axis of which is parallel to trachea. Hyoid bone �hugs� epiglottis; no subglottic narrowingAdult Larynx xerogram and schematic � relatively thin, broad epiglottis, axis of which is parallel to trachea. Hyoid bone �hugs� epiglottis; no subglottic narrowing

7. Infant Larynx Infant larynx xerogram and schematic� angled epiglottis and narrow cricoid cartilageInfant larynx xerogram and schematic� angled epiglottis and narrow cricoid cartilage

8. Laryngeal AnatomyPremature Infant

9. 7-14 Positioning for ventilation and tracheal intubation�oral (O), pharyngel (P), and tracheal (T) axes 7-14 Positioning for ventilation and tracheal intubation�oral (O), pharyngel (P), and tracheal (T) axes

10. Airway Management Oral airway use

11. Correct airway selection�relieve airway obstruction secondary to tongue with damaging laryngeal structures Correct airway selection�relieve airway obstruction secondary to tongue with damaging laryngeal structures

12. Airway Management Oral airway use Endotracheal tube size Uncuffed vs. cuffed

13. Endotracheal Tubes Used in Infants and Children

14. Distance for Insertion of an Endotracheal Tube by Patient Age

15. Airway Management Oral airway use Endotracheal tube size Uncuffed vs. cuffed Assessment for �leak� Poiseuille law -- R = 8L?/r4

16. Airway Edema EffectsAdult vs. Infant

17. Airway Management Oral airway use Endotracheal tube size Uncuffed vs. cuffed Assessment for �leak� Poiseuille law Laryngeal mask airway use

18. Selecting Laryngeal Mask Size

19. Airway Management Oral airway use Endotracheal tube size Uncuffed vs. cuffed Assessment for �leak� Poiseuille law Laryngeal mask airway use �Difficult pediatric airway�

20. Craniofacial Anomalies Cleft lip and palate Mandibular hypoplasia Craniofacial dysostosis Mandibulofacial dysostosis Hemifacial microsomia Klippel-Feil syndrome Beckwith-Wiedemann syndrome Trisomy 21 Freeman Sheldon (whistling face) syndrome Mucopolysaccharidosis Vascular malformation Hemangioma AVM Venous lymphatic malformation (cystic hygroma)

21. Fig 7-5 Larynx in children with mandibular hypoplasia (C & D)�more posterior than in child with normal anatomy (A & B) Fig 7-5 Larynx in children with mandibular hypoplasia (C & D)�more posterior than in child with normal anatomy (A & B)

22. Larynx Location in Neonate with Pierre Robin Anomaly Larynx located high in neck (C3-4) Acute angulation between laryngeal inlet (arrow) and base of tongue

23. Difficult Airway Management PREPARATION Premedication Equipment Personnel Techniques Best technique is one best performed by the experienced anesthesiologist Fiberoptic bronchoscope LMA assistance �intubating� oral airway Light wand, Bullard laryngoscope, retrograde intubation Spontaneous ventilation Oral vs. nasal Topical local anesthesia�use will assist to provide adequate anesthesia and enable use of lower volatile agent concentrations, minimizing the risk of hypoventilation

25. Unexpected Difficult Pediatric Airway Decreased time limits with loss of airway Approximate time to zero oxygen saturation from inspired concentration of 90% 4 minutes in 10-kg child 10 minutes in healthy, 70-kg adult Increased metabolic rate and decreased functional residual capacity contributes to more rapid hypoxemia Emergency cricothyrotomy or tracheostomy is rarely indicated, but possibility should be considered Cricothyroid membrane is lower in neck in young children and infants, sometimes closer to the sternal notch than initially anticipated

26. Cardiac Physiology �normal� vital signs and parameters Cardiac output = Stroke volume x Heart rate Congenital heart defects, patent foramen ovale SBE prophylaxis Cardiac arrest etiologies (Perioperative Cardiac Arrest (POCA) review)

27. Comparison of Cardiovascular Variables

28. Pulmonary Physiology �normal� vital signs and parameters Lung volume and respiratory mechanics differences Disease processes Reactive airway disease Upper respiratory tract infection Bronchopulmonary dysplasia, hyaline membrane disease Cystic fibrosis

29. Comparison of Pulmonary Variables

31. Renal Physiology Immature function GFR increases 2-3 times in 1st 3 months of life, then slower until adult levels reached at 12-24months of age Urine concentrating ability slowly reaches adult level over 6-12 months, making infant less able to compensate for fluid balance

32. Hepatic Physiology Liver function Immature function in neonate and young infant, with rapid maturation; adult levels reached in first few months of life Functional immaturity due to relatively decreased hepatic blood flows; development and growth of enzyme systems not fully induced Alteration in pharmacologic effects Ability to conjugate and catabolize substrates diminished at birth, creating longer half-life in neonate vs. child Decreased synthetic function, i.e., albumin, leads to decreased protein binding and altered pharmacodynamics

33. Pediatric Pharmacology Pharmacokinetics and pharmacodynamics Metabolism and excretion Immature liver and kidney function Intravenous anesthetics Narcotics�consider immature blood-brain barrier and decreased metabolism/excretion Neuromuscular blocking agents�more sensitive to effects but greater volume of distribution, doses essentially the same Inhalation anesthetics MAC variability Rate of uptake shortened d/t smaller FRC/body weight ratio and greater blood flow to active sites

35. Fluid Management NPO guidelines Clears up to 2 hours prior to procedure Breast milk up to 4 hours Formula, non-human milk up to 6 hours No solids after 2400 Quantity �restriction� Fluid replacement 4-2-1 rule for maintenance Intravenous line access Blood loss management ABL = EBV x Hct1 � Hct2/mean Hct

36. Estimated Blood Volume in Pediatric Patients

37. Pain Management Anticipation of analgesia needs �Simple� Acetaminophen, NSAIDS Narcotics �Complex� Regional techniques, including �caudals�

43. Thermoregulation Temperature maintenance mechanisms Heat loss mechanisms Conduction, convection, evaporation, radiation Methods to control heat loss Bair hugger, overhead radiant warmer, circuits

44. Case Preparation �Basic Pediatric Set-up� Remember, a variety of types or sizes of masks, ETT, blood pressure cuffs, laryngoscope blades, etc. should be present in the room to provide �adaptability� IV set up Medication doses Flush syringes, medication syringe sizes according to doses to be delivered

45. Pediatric Induction Preoperative sedation Decision for use done on an individual basis, requiring at least 20-30 minutes for adequate sedation; consider for those patients returning for repeated procedures Parental presence Benefit to minimize separation anxiety generally not seen until around 1 year of age, decision made by anesthesia team on individual basis Inhalation induction vs. intravenous induction �8% sevoflurane induction� vs. �gradual halothane induction� Everything should be ready to carry out the induction expeditiously, avoiding opportunity for the child to become �less cooperative�

46. Neonatal Anesthesia Warm environment Proper airway equipment available, intubation Anesthesia machine, ventilation mode Anesthetic technique Emergency medications Monitoring equipment Have 2nd pulse oximeter probe (consider pre- and postductal if appropriate), Nellcor 395 (via RT) as pulse oximeter option Precordial stethoscope Post-operative plans and transport (to NICU)

49. Larynx Location in Neonate with Pierre Robin Anomaly

51. 7-16 Intubation injuries pathogenesis schematic (A), histologic cross-section (B), and pictorial with laryngoscopy (C). 7-16 Intubation injuries pathogenesis schematic (A), histologic cross-section (B), and pictorial with laryngoscopy (C).