Campbell-Walsh Urology, 11th Edition

PART XV

Pediatric Urology

SECTION B

Basic Principles

128

Core Principles of Perioperative Management in Children

Carlos R. Estrada, Jr.; Lynne R. Ferrari

Questions

  1. Prematurity and intrauterine growth restriction are defined as infants born before:
  2. 38 weeks and weighing less than 1500 g, respectively.
  3. 37 weeks and weighing less than 2500 g, respectively.
  4. 36 weeks and weighing less than 2500 g, respectively.
  5. 37 weeks and weighing less than 1500 g, respectively.
  6. 36 weeks and weighing less than 1500 g, respectively.
  7. During the fetal stage of lung development, all branching resulting in the terminal bronchial airways occurs by:
  8. 12 weeks’ gestation.
  9. 10 weeks’ gestation.
  10. 16 weeks’ gestation.
  11. 20 weeks’ gestation.
  12. 24 weeks’ gestation.
  13. Compared with the adult heart, the neonatal and pediatric myocardium are:
  14. stiffer and less compliant.
  15. less stiff and less compliant.
  16. stiffer and more compliant.
  17. less stiff and more compliant.
  18. identical.
  19. Following the relatively rapid rise in glomerular filtration rate (GFR) during the first few months of life, adult GFR is reached by:
  20. 3 to 4 years.
  21. 4 to 5 years.
  22. 6 months.
  23. 12 to 24 months.
  24. 10 years.
  25. For a 7-month-old infant in the postoperative period who weighs 9 kg, the most appropriate maintenance fluid is:
  26. D5 1/4NS + 20 mEq/L KCl at 36 mL/hr.
  27. D5 1/2NS + 20 mEq/L KCl at 45 mL/hr.
  28. D5 1/2NS + 20 mEq/L KCl at 18 mL/hr.
  29. D5 1/4NS at 36 mL/hr.
  30. D5 1/2NS + 20 mEq/L KCl at 36 mL/hr.
  31. The school-age child typically most fears:
  32. death.
  33. that they may not meet the expectations of adults.
  34. loss of control.
  35. injury.
  36. separation from their primary caregivers.
  37. For a healthy child undergoing uncomplicated surgery, the risk of an adverse event is approximately:
  38. 1 in 10,000.
  39. 1 in 200.
  40. 1 in 2,000,000.
  41. 1 in 100,000.
  42. 1 in 200,000.
  43. Routine diagnostic testing for surgery in a healthy 12-month-old child includes:
  44. a chest radiograph and complete blood count.
  45. a complete blood count, electrolytes, and prothrombin time (PT)/partial thromboplastin time (PTT).
  46. a chest radiograph, complete blood count, and PT/PTT.
  47. hemoglobin/hematocrit determination.
  48. no studies.
  49. In preparation for surgery, children should fast from clear liquids:
  50. for 2 hours before surgery.
  51. for 3 hours before surgery.
  52. for 4 hours before surgery.
  53. for 6 hours before surgery.
  54. being nothing by mouth (NPO) after midnight.
  55. For a child 6 years of age, assessment of postoperative pain is best done by:
  56. simply asking him or her about the pain.
  57. relying on appearance, because children cannot hide their pain well.
  58. using a visual analog scale.
  59. using a faces scale.
  60. asking the child's parents.
  61. Poor and rapid metabolizers of codeine can be expected to:
  62. have good and poor pain relief, respectively.
  63. have little effect and have dangerously high plasma morphine levels, respectively.
  64. have dangerously high plasma morphine levels and little effect, respectively.
  65. have identical CYP2D6 enzyme genotypes.
  66. most likely be of North African and white descent, respectively.
  67. Surgical antibiotic prophylaxis for a major class II operation is best:
  68. administered the night before surgery.
  69. administered following incision.
  70. administered immediately after surgery is complete.
  71. administered 1 hour before incision.
  72. not recommended/administered.
  73. Blood volume in children can be most closely estimated as:
  74. 55 mL/kg.
  75. 25 to 50 mL/kg.
  76. 70 to 80 mL/kg.
  77. 100 mL/kg.
  78. 65 to 70 mL/kg.
  79. Fever (greater than 38.5° C rectal temperature) in children within 24 hours of surgery is most likely due to:
  80. urinary tract infection.
  81. surgical-site infection.
  82. deep vein thrombosis.
  83. atelectasis.
  84. dehydration.

Answers

  1. b. 37 Weeks and weighing less than 2500 g, respectively.A baby born before 37 weeks’ gestation is considered premature. The severity of prematurity may be indicated by the birth weight, although these two factors are not necessarily related. Infants weighing 2500 g or less at birth are considered low birth weight (LBW) in prematurity, but in an infant born full term, this weight would indicate intrauterine growth restriction (IUGR). This is an important distinction, because full-term neonates with IUGR usually have different problems than do premature infants.
  2. c. 16 Weeks’ gestation. Proper intrauterine growth and development are dependent on presence of normal amniotic fluid volume.Of particular relevance to urologists is lung development, which is dependent on amniotic fluid. The fetal stage of lung development begins at 7 weeks’ gestation and proceeds to term. By the end of the 16th week of gestation, all lung branching occurs, resulting in the terminal bronchial airways. After this time, the only further growth that occurs is elongation and widening of existing airways.
  3. a. Stiffer and less compliant.The neonatal and pediatric myocardium is stiffer and less compliant compared with the adult heart. This results in diminished preload capacity so that increases in end-diastolic ventricular volume and increases in right ventricular pressure result in decreased cardiac output at lower levels than in adult patients. In addition, infants and children have relatively higher resting heart rates. As a result, cardiac output in children is heart-rate dependent, because the stroke volume is relatively fixed. Decreases in heart rate in infants and children will result in decreases in cardiac output to a greater extent than a similar decrease in heart rate in an adult patient. A reduction of a child's heart rate to that of a typical adult would result in marked decrease in cardiac output.
  4. d. 12 to 24 months.In utero, renovascular resistance is high, limiting renal blood flow. Immediately following birth, the distribution of renal cortical blood flow changes, with increased perfusion of the outer cortex and increased reactivity of the renal vascular bed. Consequently, the glomerular filtration rate (GFR) rises quickly despite renal blood flow remaining unchanged. In addition, water and electrolyte homeostasis is difficult to predict. GFR and tubular function double by 1 month of age (Kaskel),* and during the first 3 months of life, renovascular resistance continues to decrease, which results in further rises in GFR. Following this relatively rapid rise, GFR continues to increase more slowly toward adult levels, which are reached by 12 to 24 months of life. The maturation of renal tubular function lags behind the maturation of glomerular function, and therefore the neonate can concentrate urine to only approximately 50% of adult capability.
  5. e. D5 1/2 NS + 20 mEq/L KCl at 36 mL/hr.The total requirements for maintenance fluids can be calculated by using the Holliday-Segar formula. After the fluid requirement is calculated, children usually receive either D5 1/4NS + 20 mEq/L KCl or D5 1/2NS + 20 mEq/L KCl. Children who are younger than 6 months old are generally given the solution with 1/4NS, because of their high water needs per kilogram. Children 6 months and older, however, should receive the solution with 1/2NS.
  6. b. That they may not meet the expectations of adults.Age-appropriate treatment of children is essential to provide the best possible perioperative experience. Infants fear separation from their primary caregivers and exhibit stranger anxiety. Toddlers fear loss of control, so enabling a child to make choices, such as asking if the child has a color preference for his or her hospital gown, will diminish anxiety. Preschool-age children fear injury; they may fear, for example, that a blood draw may result in not enough blood being left in their bodies. The school-age child typically fears that he or she may not meet the expectations of adults. They are reluctant to ask questions for fear that they should already know the answer. Adolescents fear death and usually do not understand bodily functions.
  7. e. 1 in 200,000.Most parents will state that they experience more anxiety about the anesthetic than the risks of the surgery. For a healthy child undergoing uncomplicated surgery, the risk of an adverse event is approximately 1 in 200,000. The risk of death under anesthesia is the most feared complication. This risk is 1 in 10,000 for all patients of any age undergoing any surgical procedure. However, the risk of death directly attributable to the anesthetic approaches zero, although the risk of cardiac arrests due to anesthesia remains approximately 4.5 in 10,000. The incidence of anesthetic-related complications and death is highest during the first year of life at 43:10,000, but this decreases dramatically during the second year of life to 5:10,000. Anesthetic risks increase by a factor of 6 during emergency procedures in all age groups.
  8. e. No studies.Routine diagnostic testing in preparation for surgery is rarely indicated in healthy children, and studies that are ordered should be selected based on the general medical health of the patient and the procedure being performed. In general, measurement of hemoglobin/hematocrit in a healthy child undergoing elective surgery is unnecessary. A hemoglobin/hematocrit should be measured if significant blood loss is anticipated or if the child is younger than 6 months old or was born prematurely.
  9. a. For 2 hours before surgery.It is no longer advisable or safe to restrict children to “NPO after midnight.” The American Society of Anesthesiologists recommends fasting from clear fluids for 2 hours before anesthesia. Clear liquids consist of water, nonparticulate juices (e.g., apple, white grape), Pedialyte, and Popsicles. Fasting from breast milk for 4 hours and formula for 6 hours is recommended. The suggested fasting period for solid food is 6 hours for regular meals and 8 hours for fat-containing meals. However, individual institutions may have specific practice guidelines.
  10. d. Using a faces scale.In general, children 8 years and older can reliably report pain on the visual analog scale used in adults. Children between the ages of 3 and 7 years can better report pain by using a faces scale that uses a series of drawings depicting increasing levels of distress.
  11. b. Have little effect and have dangerously high plasma morphine levels, respectively. Codeine is a relatively weak opioid given its extremely low affinity for opioid receptors, and most of its analgesic effect is due to the 10% that is metabolized to morphine. The metabolism to morphine is predominantly by O-demethylation by the cytochrome P450 enzyme CYP2D6, which is known to show genetic polymorphism. Therefore, variations in CYP2D6 will result in variable abilities to metabolize codeine. In this way, individuals may be classified as poor metabolizers or ultrarapid metabolizers, depending on the phenotype of their CYP2D6 enzyme.
  12. d. Administered 1 hour before incision.The timing of surgical antimicrobial prophylaxis is critically important, and the first dose should be given 30 minutes to 3 hours before incision to achieve bactericidal levels of the antibiotic at the site of incision.
  13. c. 70 to 80 mL/kg.Blood volume in children varies with age, but can be estimated as 70 to 80 mL/kg.
  14. d. Atelectasis.Postoperative fever is a very common early surgical problem, and its etiology is taught in the first days of medical school surgery clerkships as the four Ws: wind, wound, water, and walking. “Wind” refers to atelectasis, “wound” to a surgical-site infection (SSI), “water” to a urinary tract infection (UTI), and “walking” to fever caused by deep vein thrombosis (DVT) in the lower extremities. Fever, defined as greater than 38.5° C rectal temperature, is common within 24 hours of surgery and is usually caused by atelectasis.

Chapter review

  1. Infants weighing 2500 g or less at birth are considered low birth weight (LBW) in prematurity, but in an infant born full term, this weight would indicate intrauterine growth restriction (IUGR). This is an important distinction, because full-term neonates with IUGR usually have different problems than premature infants.
  2. Fluid requirements per 24 hours in children are calculated according to weight as follows: 1- to 10 kg, 100 mL/kg; 11 to 20 kg, + 50 mL/kg; and greater than 20 kg, + 25 mL/kg. Children who are less than 6 months old are generally given the solution with 1/4NS, because of their high water needs per kilogram. Children 6 months and older, however, should receive the solution as 1/2NS.
  3. Lung development is dependent on an adequate amount of amniotic fluid.
  4. A fetus with severe oligohydramnios may suffer pulmonary fibrosis.
  5. Cardiac output in children is heart-rate dependent; the stroke volume is relatively fixed; infants have high heart rates, limiting their ability to increase cardiac output by increasing heart rate.
  6. Neonates have an increased susceptibility to infection due to impaired T-lymphocyte function and deficiency of immunoglobulins.
  7. The immune system does not become fully competent until approximately 8 years.
  8. Anesthesia is most risky in the first year of life.
  9. A family history of anesthesia-related events, liver problems, or malignant hyperthermia is part of the preoperative assessment.
  10. Children should take clear liquids as long as 2 hours before anesthesia; solid foods should not be consumed for 8 hours prior to anesthesia.
  11. In premature infants who undergo anesthesia, the major risk postoperatively is apnea; similarly, in full-term infants younger than 4 weeks of age, apnea is the major postoperative risk.
  12. Children with spina bifida have a high incidence of latex sensitivity.
  13. In response to planned surgery, infants fear separation, toddlers fear loss of control, preschool-age children fear injury, school-age children fear that they may not meet expectations of adults, and adolescents fear death.
  14. A preoperative hematocrit should be obtained in children born prematurely and in those younger than 6 months.
  15. It is unknown whether anesthesia is neurotoxic to the developing brain.
  16. Children with ventriculoperitoneal (VP) shunts should be evaluated for a functional shunt preoperatively.
  17. Children are at significant risk for hypothermia intraoperatively.
  18. The maturation of renal tubular function lags behind the maturation of glomerular function, and therefore the neonate can concentrate urine to only approximately 50% of adult capability.
  19. Codeine is a relatively weak opioid given its extremely low affinity for opioid receptors, and most of its analgesic effect is due to the 10% that is metabolized to morphine.

* Sources referenced can be found in Campbell-Walsh Urology, 11th Edition, on the Expert Consult website.



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