Pediatric Management & Pharmacology

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Describe the preoperative fasting (NPO)
guidelines for children: (1) < 6 months old;
(2) 6-36 months old; and, (3) > 36 months

Fasting guidelines are: (1) Children <6 months old: restrict solids for 4 hours & clear liquids for 2 hours. (2) Children 6-36 months: restrict solids for 6 hours & clear liquids for 3 hours. (3) Children > 36 months old: restrict solids for 8 hours & clear liquids for 3 hours. The American Academy of Pediatrics/American Society of Anesthesiologists task force
has set recommendations that "advise restriction of clear fluids for 2 hours, breast milk for 4 hours, formula or light meals for 6 hours, and fatty solid meals for 8 hours." The pattern is to start NPO at 2 hours for clear liquids & add 2 hours for each increasingly "fatty" meal.

Positive pressure ventilation by bag and mask has been instituted on the neonate during resuscitation. When is endotracheal intubation indicated?

During neonatal resuscitation, prompt endotracheal intubation is indicated if there is no immediate (<30 seconds) improvement in the clinical condition of the neonate with positive-pressure ventilation with a face
mask. (There are many steps in the algorithm for resuscitation of the newly born infant at which endotracheal intubation may be considered: see Chestnut, page 133 for the complete algorithm.)

When should immediate endotracheal intubation be considered during neonatal resuscitation?

Immediate endotracheal intubation of the neonate should be considered for situations in which bag and mask ventilation is likely to be ineffective, for example, extreme prematurity with low pulmonary compliance secondary to surfactant deficiency. Other situations in which bag and mask ventilation may be ineffective are large bilateral pleural effusions and congenital diaphragmatic hernia

What is the appropriate internal diameter of
the endotracheal tube for the premature newborn? For the full -term newborn?

The appropriate internal diameter of the endotracheal tube is 2.5-3.0 mm for the premature newborn and 3.0- 3.5 mm for the full-term newborn

What endotracheal tube size and length are required for the neonate, 2-year-old, 6-year-old and 10-year-old?

Neonate = 3.0-3.5 and 10 cm length; 2-year-old = 4.5 and 13 cm length; 6-year-old = 5.5 and 15 cm length; 10-year-old = 6.5 and 17 cm length

What is the appropriate internal diameter of the endotracheal tube for the 12 to 20-month-old child?

4.0 mm

Write the formula for calculating the internal diameter of the endotracheal tube for the child who is greater than 20 months of age. Calculate the appropriate internal diameter of the endotracheal tube for a 5-year-old child.

For children over 20 months, 4.0 + age {years)/4 = the internal diameter (ID) needed. 4.0 + 5/4 = 5.0 mm internal diameter endotracheal tube, for the 5-year-old

How is the French size of the endotracheal tube determined for a child? What endotracheal tube size is required by a six-year-old?

The French size for a child is age (years) + 18. Example: A six-year-old will require a 24 French ET tube (6 + 18 = 24).

How is the length of the endotracheal tube from the mouth determined, in cm?

[10 + age (years)]/2.

What size (French) suction catheter should be used to clear the endotracheal tube of the intubated neonate? The intubated 2-year-old? The intubated 6-year-old?

The appropriate size (French) of suction catheter for clearing the endotracheal tube of the intubated child is: neonate-8 Fr, 6 months to 2 years - 10 Fr, and 2 to 12 years -14 Fr.

How many days post gestation is it safe for surgery in the full-term infant? For the preterm infant, surgery should be delayed how long post-conception?

Surgery is safe from the 15th through 56th day post gestation in the fullterm infant. Elective or outpatient procedures should be deferred until the preterrn infant reaches the age of at least 60 weeks post-conception

Surgery in neonates poses a major concern, development of apnea in the postoperative
period. Which neonates are at the highest risk for postoperative apnea?

Neonates at highest risk for postoperative apnea are those born prematurely, those who have multiple congenital anomalies, those with a history of apnea and bradycardia, and those with chronic lung disease

Would a formerly premature infant be a candidate for outpatient surgery? What are the anesthetic concerns for the formerly premature infant?

No, the formerly premature infant is not an appropriate candidate for outpatient surgery. Formerly premature infants (less than 46 weeks postconceptual age), even if healthy, have an increased rate of post-anesthetic apnea & bradycardia. These formerly premature infants should have
cardiorespiratory monitoring for a minimum of 24 hours postoperatively & thus are not good candidates for ambulatory day surgery

The infant patient is high-risk for postoperative
apnea. What agent may be given prophylactically to decrease the risk of apnea?

The infant at risk for postoperative apnea may be given caffeine prophylactically to ensure adequate serum levels exist prior to surgery & during the postop period. Caffeine is a respiratory and CNS stimulant & is generally preferred
to theophylline because caffeine has a wider therapeutic margin & a decreased propensity for toxicity. The recommended loading dose is 10 mg/kg of caffeine
base, which is often obtained from 20 mg of caffeine citrate. The clinical effects of caffeine may last several days after a single dose, but do not administer caffeine & then discharge the patient, assuming that the caffeine will prevent apnea

What is retinopathy of prematurity?

Retinopathy of prematurity (ROP), formerly known as retrolental fibroplasia, is a fibrovascular proliferation overlying the retina that leads to progressive visual loss. ROP occurs almost exclusively in preterm infants. The risk of ROP is inversely proportional to birth weight, and is associated with neonatal oxygen exposure, apnea, blood transfusion, sepsis, & fluctuating levels of carbon dioxide

Neonatal retrolental fibroplasia is a result of oxygen toxicity above what % inspired oxygen?

Above 40% oxygen. Physiological studies indicate that the premature infant is probably safe with up to 40% oxygen but some believe that complete safety can be achieved only at the normal inspired oxygen concentration.

At what gestational age does the risk of retinopathy of prematurity become negligible?
Why?

The risk of retinopathy of prematurity becomes negligible after 44 weeks postconception because retinal vasculogenesis is complete between 42-44 weeks postconception

What Pa02 and Sa02 are appropriate during
anesthesia for the premature infant?

There appear to be no clearly established guidelines in the anesthesia literature. Sa02 in the 90-95% range (Pa02 = 60-80 mm Hg) is believed to be reasonable for the premature infant. The goal specified by guidelines of the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists is a Pa02 between 50 and 80 mm Hg in premature infants.

A neonate is undergoing a surgical procedure with the use of a spinal blockade. What sign would indicate a "high" or "total" spinal?

Decreasing oxygen saturation is the earliest sign of a high or total spinal in the neonate. A high or total spinal, produced either with a primary spinal technique or secondary to an attempted epidural, presents as respiratory
insufficiency rather than hypotension owing to the relatively immature sympathetic nervous system in the neonate. With an immature SNS, the CV parameters are remarkably
stable in the neonate with a high or total spinal

How do infants react to hypoxia?

Infants react to hypoxia with bradycardia progressing to cardiac arrest

Where should PaC02 be maintained during intracranial surgery in children?

For children, PaC02 may be reduced to 20-25 mmHg

What Pa02 is desirable when ventilating a premature infant for surgery?

60-80 mmHg

What drugs will have a larger volume of distribution in the infant compared with the adult? What drugs will have a smaller volume of distribution in the infant compared with the adult?

The infant's extracellular body fluid compartment is large compared to the adult, so water soluble drugs will have a larger volume of distribution in the infant compared with the adult. Conversely, lipid soluble drugs will have a smaller volume of distribution in the infant compared with the adult.

What is the most prominent muscarinic action of a bolus of succinylcholine in the pediatric patient? How can this action be prevented?

Bradycardia develops in response to succinylcholine; for this reason, atropine should be administered prior to succinylcholine

How much nondepolarizing muscle relaxant does a pediatric patient require compared with adults on a weight basis? Succinylcholine?

Neonates, infants and children require the same dose of nondepolarizing neuromuscular relaxant as adults. Neonates require twice as much succinylcholine on a body weight basis than older children or adults

Given that the infant has greater sensitivity to nondepolarizing neuromuscular relaxants than the adult (because the neuromuscular junction of the neonate is immature), why is the dose administered on a weight basis the same for infants and adults?

Infants have a greater volume of distribution for muscle relaxants. The increased volume of distribution, normally requiring a greater amount of drug, is offset by the increased sensitivity of nondepolarizing muscle relaxants at the neuromuscular junction. Thus, the infant dose of nondepolarizer is the same as the adult dose on a weight basis

State two reasons why neonates require
more succinylcholine on a mg/kg basis than
adults.

(1) Neonates have a larger volume of distribution for succinylcholine than adults. 40-50% of body weight of neonate is extracellular fluid (ECF) whereas in the adult ECF is only 20-25% of body weight. Succinylcholine
distributes in the extracellular volume so more drug is needed on a per kg basis. (2) Also, the neuromuscular junction is immature (less sensitive) in the neonate, so more drug is needed on this basis

Define ED90. State if the ED90 for succinylcholine
is increased, decreased, or unchanged in the neonate compared with the adult, and indicate what this means.

ED90 is the dose of drug that is effective in 90% of the population (ED90 = effective dose in 90% of population). The ED90 for succinylcholine is increased in the neonate compared with the adult. An increased ED90 means that a larger dose of succinylcholine must be given to the neonate to achieve adequate paralysis.

As you know, neonates require a higher dose of succinylcholine compared to adults. This is due to both an immature neuromuscular junction and greater body water content per unit weight. How would the ED95 for succinylcholine compare between a neonate and an adult-the same, higher, or lower?

The ED95 of succinylcholine for the neonate would be greater than that for the adult. Specifically, for succinylcholine the ED95 = 620 mcg/kg for the neonate and the ED95 = 290 mcg/kg for the adult. This simply states
the need for greater dosing of succinylcholine in the neonate, compared to the adult.

Compare the actions of vecuronium (Norcuron)
in the infant and the adult with respect to potency, onset, duration of action, and recovery.

Vecuronium (Norcuron) has similar potency in infants and adults. Onset is more rapid in infants, duration of action is longer in infants, and recovery is slower in infants, compared to adults.

How does an infant's quantity of plasma proteins, body fat, and muscle differ from the adult?

Plasma proteins, body fat, and muscle are reduced in the infant compared with the adult. Decreased plasma proteins mean more free drug is available to produce clinical effects. A lower dose of drug may be indicated.

A two-year-old develops laryngospasm postoperatively and becomes bradycardic. Should atropine be given prior, concurrently, or after succinylcholine? Explain your answer.

If continuous positive pressure of 10-15 cm H20 does not break the laryngospasm, then atropine 0.02 mg/kg followed by succinylcholine (1 mg/kg IV; 4 mg/kg IM) is needed. Succinylcholine mimics the effect of acetylcholine at cardiac muscarinic receptors, which can precipitate more severe bradycardia, junctional rhythms, or sinus arrest

What is the appropriate volume for a pediatric epidural blood patch?

In the child who is awake, the practitioner should stop the blood infusion once the child feels discomfort or pressure in the back. In the anesthetized patient, no more than 0.3 mL/kg of blood should be injected into the epidural space.

For the pediatric patient weighing between 2 and 20 kg, what volume (mL/kg) of 0.25% bupivacaine (mL/kg) should be administered caudally for a block to L-1 or T -12? To T-10? To T-4 orT-5?

0.35 mL/kg for L-1 to T -12 level block; 0.5-0.75 mL/kg for a T -10 level block; 0.75-1.25 mL/kg for a T-4 or T-5 level block

An acceptable dose of bupivacaine for an infant receiving a caudal anesthetic block would be what? Give answer in mL/kg.

For perineal surgery use 0.5 mL/kg and for lower abdominal surgery use 1.0 mL/kg of bupivacaine (0.25%) with 1:200,000 epinephrine

What is the maximum dose of 0.25% bupivacaine
that should be used for pediatric caudal anesthesia?

Bupivacaine (0.25%) at a volume of 1 mL/kg up to a maximum of 25 mL can provide 3 to 6 hours of anesthesia for surgical procedures below the level of the diaphragm

Is elimination of amide local anesthetics shortened or prolonged in the neonate compared
with the adult?

The half-time of elimination of amide local anesthetics is prolonged 2-3 times in the neonate but approaches adult values after six months of age

Which local anesthetic is not metabolized in neonates?

Mepivacaine is not metabolized in neonates; this is controversial, but generally accepted. "The neonatal enzyme systems are adequately developed to metabolize most drugs, with the possible exception of mepivacaine."

Of the following drugs administered to the pediatric patient for sedation, which will have the shortest duration of action: ketamine (rectal or IM), chloral hydrate (PO), methohexital (rectal), or propofol (IV)?

Propofol has the shortest duration of action because it is administered IV. The duration of action of a bolus of propofol is 5-10 minutes. Ketamine has a duration of 12-25 minutes when administered rectally or IM. Midazolam has a duration of 2-6 hours when administered IM. Methohexital
has a duration of 30-90 minutes when administered rectally. Chloral hydrate, the most commonly used hypnotic for monitored conscious sedation by nonanesthetists, has a duration of 30-60 minutes (PO). Note: IV thiopental has a duration of 5-15 min, which is similar to the duration of propofol.

Compare the onset and duration of intravenous
morphine in the neonate with the onset and duration of intravenous morphine in the adult?

The onset of action of morphine is faster in the neonate compared with the adult, possibly because of greater penetration of morphine through the blood:brain barrier and greater sensitivity of the respiratory centers to morphine. The duration of action of morphine will be longer in the neonate because, during the first month, metabolism of morphine by the immature cytochrome P450 system is reduced.

Compare the duration of intravenous morphine
in the infant and child with the onset and duration of intravenous morphine in the adult?

The duration of action of morphine is shorter in the infant and child because, after the first month, metabolism of morphine by the mature cytochrome P450 system is increased as a result of greater hepatic blood flow.

State 3 reasons why the uptake of anesthetic
drugs is typically faster in children than in adults

(1) The Childs higher alveolar ventilation per weight accounts
largely for this effect. (2) Increased cardiac output with greater distribution to the vessel-rich groups combined with lower muscle mass allows more of the agent to concentrate in vital organs, especially the brain. (3) Anesthetic agents appear to be less blood soluble in children than in adults, that is, the agents work faster in children than adults.

Nitrous oxide (N20) should be avoided in what pediatric procedures?

Nitrous oxide should be avoided in numerous procedures including: diaphragmatic hernia, bowel obstruction, pneumoencephalography, tympanoplasty, congenital emphysema, lung cysts, pneumothorax, necrotizing enterocolitis, patent ductus arteriosus (PDA), and omphalocele repair.

Give the two most important reasons why children are induced faster than adults with inhalational agents.

Children have (1) a smaller functional residual capacity per unit of body weight and (2) a greater blood flow to the brain

What is the most common type of delirium in children?

In children, emergence delirium is more common. Emergence delirium occurs within minutes of regaining consciousness

Which fluid is most appropriate for a normal six-month-old patient requiring surgery?

For short procedures, D5lactated Ringer's is appropriate. For long procedures, lactated Ringer's is appropriate with separate D5W or D10W at a rate of 4-6 mL/kg/min after blood glucose levels are checked

How many breaths per minute should be produced by the ventilator for the neonate? For the adult?

30-50 breaths per minute for the neonate and 12-16 breaths per minute for the adult

What are two advantages of using Randal Baker
masks in pediatrics?

The Randal-Baker mask is designed to fit the facial ontours more closely and to reduce dead space (firm rubber).

The child becomes unruly and combative in the pre-operative period. What agents are appropriate in this situation? Specify the dose and routes of administration of each agent on the list.

(1) Methohexital (10% solution): 25-30 mg/kg rectally, produces sleep in 8-10 minutes if the child weighs less than 20 kg. (2) Ketamine: up to 10 mg/kg IM; 10 mg/kg rectally; 6-10 mg/kg orally; 3-6 mg/kg intranasally. (3) Midazolam: IM (.025-.05 mg/kg); oral (0.5-0.75 mg/kg), rectal (.75-1.0 mg/kg), nasal (0.2 mg/kg), sublingual (.2 mg/kg). (4)Scopolamine: 0.1 mg IM for 6-12 mo.; 0.15 mg for 1-5 yrs

What is the best criteria for determining premedication dosages in kids?

Body weight of child

What 9 cardiovascular signs indicate fetal cocaine toxicity in the newborn of a cocaine addicted mother?

(1) arterial hypoxemia, (2) increased blood pressure, (3) increased heart rate, (4) increased cerebral blood flow, (5) reduced cardiac output, (6) reduced stroke volume, (7) right ventricular conduction delay, (8) right ventricular hypertrophy,
and (9) ST segment and T -wave changes.

What is the most commonly used analgesic for pediatric outpatients?

Acetaminophen is the most commonly used mild analgesic for pediatric outpatients. The initial dose is often administered rectally (up to 45 mg/kg) prior to awakening from anesthesia. Supplemental doses are then given orally (10 mg/kg every 4 hours or 20 mg/kg every 6 hours) to maintain adequate blood levels and effective analgesia

What is the drug of choice and dosing for prophylaxis for pediatric endocarditis?

Standard general prophylaxis for pediatric endocarditis is amoxicillin, 50 mg/kg orally 1 hour prior to procedure

The pediatric patient is scheduled for a radiofrequency ablation of an aberrant conduction pathway (e.g., Wolff-Parkinson White syndrome). Why is a general anesthetic typically required for this scenario?

Radiofrequency ablation is a nonsurgical approach designed to eliminate atrial or ventricular re-entrant tachyarrhythmias. The technique requires mapping & precision ablation of the aberrant pathway, using a radiofrequency ablation catheter. During the ablation, unexpected movement may result in catheter dislodgment & damage to normal conducting tissue; therefore, general anesthesia is usually required in younger children. Anesthetic agents and techniques should be chosen to maintain circulating catecholamines & avoid suppression of arrhythmogenesis, for identification of the aberrant pathway.

Describe the 4 steps to treating hyperkalemia in the neonate.

Emergent treatment of hyperkalemia in the neonate centers around antagonizing the cardiac effects of excess K+ -administer calcium as calcium chloride (0.1-0.3 mL/kg of 10% solution) or calcium gluconate (0.3-1.0 mL/kg 10% solution) over 3-5 minutes. Return K+ to the intracellular space by correcting acidosis through administration of sodium bicarbonate, mild hyperventilation, & a beta-agonist. Maintain K+ in the intracellular space by glucose + insulin infusion, 0.5-1.0 g/kg glucose w/ 0.1 U/kg insulin over 30-60 minutes. Remove whole body K+ burden by Kayexalate or dialysis & correct the underlying etiology.

An infant has a life-threatening succinylcholine-induced hyperkalemia: what is the definitive treatment?

The definitive treatment of succinylcholine-induced hyperkalemia is IV calcium (10 mg/kg calcium chloride or 30 mg/kg calcium gluconate or more). This restores the gap between the resting membrane potential of the cardiac cells & the threshold potential for depolarization. Repeated
doses of calcium must be administered together with CPR, epinephrine, sodium bicarbonate, glucose & insulin, & hyperventilation until the arrhythmias abate

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