Pediatric Drug Administration

This CE activity is approved by EMS World Magazine, an organization accredited by the Continuing Education Coordinating Board for Emergency Medical Services (CECBEMS) for 1 CEU. To take the CE test that accompanies this article, go to www.rapidce.com to take the test and immediately receive your CE credit. Questions? E-mail editor@EMSWorld.com.

OBJECTIVES

• Review anatomical and physiological features of pediatric patients that influence drug administration
• Discuss pediatric pain management

      As you prepare to leave a community event where you've been on standby, a mother hurries to your tent with her 3-year-old daughter, who has a wheezy cry and is drooling. The mother tells you the child is allergic to bee stings and was just stung by three bees. Your partner alerts dispatch for a paramedic squad while you do a quick exam and find three sting sites on the girl's right arm, hives rapidly spreading across her chest and face, and audible wheezes. Oxygen is applied and, as you reach for an epinephrine auto-injector, your partner asks if you need the pediatric auto-injector. Looking at the adult auto-injector in your hand, you remember that young children like your patient need special doses of medication.

   Why does a child need a special dose? How is their body different from an adult's? Are there other types of patients who should also be given special consideration? This article discusses special considerations for pediatric drug administration.

   Children's bodies are a world apart from adults'. One of the easiest ways to understand why drugs may have different actions and different effects in children is to take a system-by-system approach to pediatric anatomy.

NEUROLOGIC SYSTEM

   An incredible amount of blood circulates oxygen, nutrients and other chemicals into the brain. Because our brain cells are very sensitive to harmful substances and cannot be reproduced, it is important to keep harmful chemicals out of brain matter. As a result, the epithelial cells, or outermost brain cells that connect with circulating blood at the capillary level, have grown very tightly together. This layer of tightly packed epithelial cells, which is called the blood-brain barrier, prevents most proteins and polarized molecules from entering the brain. While lipid-soluble molecules can pass through the blood-brain barrier easily, most other chemicals are kept out.¹

   The protective blood-brain barrier in adults is not well developed in children, and is underdeveloped in premature infants, as their bodies' connective tissues have not yet been strongly formed. While the blood-brain barrier normally keeps potentially harmful drugs and other toxins from entering the brain, these same toxins and drugs can easily enter a child's brain. Extreme caution is required when administering drugs to these young patients. When the blood-brain barrier is weakened, certain drugs can potentially harm the neonatal infant's brain.

   Drugs with known side effects that include neurological impairment require careful administration. These side effects are more common in the pediatric patient. For example, morphine is known to cause respiratory depression and sedation by slowing responses in the central nervous system. This effect can be seen more dramatically and at lower doses in children.

CARDIOVASCULAR SYSTEM

   A child's cardiovascular system is not as strong as an adult's, and cardiac output is significantly lower. The heart is less developed and cannot increase the strength of contraction as well as an adult heart.² As a result, the pediatric heart compensates best by increasing its rate instead of its contractile force. Peripheral vasoconstriction occurs earlier in pediatric patients and is less effective at increasing circulating blood volume. Tachycardia, or rapid pulse rate, needs to be recognized as a compensation mechanism. It is usually OK if it persists until the underlying problem can be corrected.

   Consider the following case: You've been called to a country home nearly 25 minutes outside of your normal response district for a lethargic child. Upon arrival, you find a listless 3-year-old male who is pale and clammy, and pays no attention to you as you approach his bed. His mother tells you Mark has been vomiting and had diarrhea for four days, and has not eaten or kept water down since he got sick. While you apply oxygen, your partner takes the following vital signs: heart rate 148 and weak, respiratory rate 34 and rapid, blood pressure 72/40; skin pale, cool and clammy; temperature 102°F.

   Mark's body is trying to compensate for hypovolemia, which he cannot do as well as an adult patient with the same problem. We all compensate to maintain a normal cardiac output (stroke volume times heart rate [SV x HR]). While adults can increase preload to maintain a high stroke volume and increase heart rate, Mark can only effectively increase heart rate. The pediatric patient's stroke volume decreases as blood volume decreases.

   Like Mark, sick children compensate by changing their vital signs and the appearance of their skin. Since pediatric patients have a much smaller blood volume than adults, they must vasoconstrict earlier and more dynamically. Pale, cool, clammy skin can develop very rapidly. Consider a 150mL blood loss: In a small pediatric patient, this loss can trigger decompensated shock, while an adult patient can handle the loss well. Tachycardia is a common but non-specific response to any increase in the child's metabolic needs, including increased oxygen demand, cardiac output or energy for physical activity.¹

   Seek out the cause of any tachycardia to determine what the child is compensating for. A persistently bradycardic heart rate is a serious finding in children and is most often triggered by hypoxemia.¹ Children also compensate with tachypnea, or fast breathing.

   EMS providers must understand that a child's vital signs (see Table 1) are quite different from the adult's. Children have a much higher basal metabolic rate than adults. To adjust for this, they need higher cardiac output and higher oxygen consumption. Because of the relatively small size of their heart and lungs, the child's heart rate and respiratory rate are both higher. Blood pressure is lower because children do not have the same peripheral vascular resistance as adults. The specific vital sign numbers are not as important as noting how the patient's vital signs change, or trend, over time. Rather than focusing on a single set of vitals, or a single number obtained, note whether the patient's vital signs change with your interventions. Determine if they are returning toward normal or becoming more abnormal and adjust your treatment accordingly.

TABLE 1: PEDIATRIC VITAL SIGNS

BODY COMPOSITION

   Relative to their size, neonates and newborns consist of up to 70% water, which decreases to about 55% by adulthood.³ This means water-soluble drugs, such as acetaminophen, will be relatively more dilute in a child than an adult. Because the child's circulating blood volume is very small, dehydration can quickly affect how well drugs are transported by the bloodstream throughout the body.¹

   As we grow through childhood, our circulating blood volume is determined by weight. Neonatal patients have a blood volume of 85-90 mL/kg, infants 75-80 mL/kg, children 70-75 mL/kg, and, during the adolescent years, 65-70 mL/kg. While the milliliters per kilogram are decreasing as a child grows, the weight increases so dynamically that the total fluid volume increases drastically. Thus, older children can more easily tolerate fluid and/or blood losses and have a much greater total volume in which to dilute drugs. Comparing a 4kg infant and a 40kg child, how much blood does each have available to dilute a given drug volume?

   Half of the pediatric patient's fluid is in the extracellular space, whereas the adult patient's extracellular fluid is only 20%.¹ This means that fluid loss in the pediatric patient can very rapidly affect more of the total body fluid reservoir than with an adult. Intracellular fluid reserves available to the adult patient are not readily available to the pediatric patient. As a result, dehydration has a more dynamic effect on the patient's ability to compensate.

RESPIRATORY SYSTEM

   An incredibly significant difference in pediatric patients is their relatively small airway size, which means excessive secretions and inflammation can easily compromise the airway.¹ This makes early administration of drugs to dry airway secretions and promote bronchodilation very important to pediatric patients in respiratory distress.

   Supplemental oxygen is also a key therapy for pediatric patients, in whom oxygen consumption is almost twice that of adults.² Oxygen consumption is measured in milliliters(mL) of oxygen per gram of weight for each organ in the body. The typical adult brain requires 3mL of oxygen for every 100g (grams) to function for 1 minute; a child's brain requires twice that, or 6mL of oxygen for every 100g. The higher oxygen consumption rate results from the child's rapidly growing organs. Pediatric patients do not tolerate hypoxemia, or low blood-oxygen saturation levels. A major sign of significant hypoxemia is bradycardia.

GASTROINTESTINAL SYSTEM

   A child's stomach is extremely small compared to an adult's. While the adult stomach can hold between 2 and 3 liters, a 1-year-old's stomach capacity is 360 mL, while a 30-day-old term infant's stomach capacity is only 90 mL.¹ Administering multiple oral drugs to young children can potentially reduce the amount of food they are capable of consuming. Fortunately, children process food more than twice as fast as an adult. This means that orally administered (PO) drugs can be absorbed and enter the circulatory system faster than in an adult patient.¹

   There are two key considerations about stomach size that directly affect EMS care. The rapid absorption rate is a benefit when administering PO medications, such as liquid acetaminophen for fever or pain; however, ingested toxins will also enter circulation twice as fast, leading to a more rapid onset of deleterious effects. Adults generally can receive oral activated charcoal up to one hour after toxin ingestion and the charcoal will inhibit absorption. Rapid absorption in the child's GI tract means that for activated charcoal to be beneficial, earlier administration is necessary. Knowing the patient's stomach size can be a benefit when considering toxin and poison ingestion, as it can help predict the maximum amount ingested, especially if the patient vomits a measurable amount of liquid. Stomach size importance is also illustrated when considering oral drug administration. Administered as 1g activated charcoal per kilogram of body weight, you must consider the concentration of the activated charcoal to ensure you do not overfill the stomach.

   Consider this case: You've been dispatched to a 2-year-old female who reportedly drank bleach. En route to the scene, first responders relay to you that the patient is crying and has a strong odor of bleach on her breath after being found with a spilled bottle of bleach beside her. When you arrive on scene, you remove the patient's bleach-soaked clothing, flush her skin to help prevent burns and quickly carry her to your ambulance. Sarah's sobbing mother tells you Sarah had just finished lunch an hour ago and has been exploring everything lately. She says she forgot to put the bleach back on the shelf after using it to clean, and she doesn't know how much Sarah may have consumed. Sarah suddenly looks scared, and you reach for an emesis bag just as she vomits up 500 mL of clear emesis and food pieces that smell strongly of bleach. Because of her age, you can estimate that her stomach probably did not have space for much more bleach than was just vomited, but you advise her mother that Sarah still needs to be seen in the emergency department.

ENDOCRINE SYSTEM

   Pediatric patients have much smaller glycogen stores than adults, and their large brain-to-body mass ratio increases their glucose demand. This predisposes children to hypoglycemia and suggests that glucagon may be less effective than for an adult. Another endocrine difference is in metabolism. Metabolism, in regard to drugs, refers to the body's changing the drug from its original form into another chemical structure or form. Some drugs must be metabolized to be utilized by the body. All drugs must be metabolized to be converted into a product the body can eliminate as waste.

   The newborn baby's metabolism is significantly slower than an adult's, meaning the neonate's body will convert and remove drugs much more slowly. However, within a few short years, their metabolic rate accelerates to three times that of an adult's, leading to faster drug metabolism (biotransformation). Throughout childhood, metabolism remains elevated to facilitate growth as a gradual rate decline occurs. By onset of adolescence, a child's metabolism is roughly that of an adult.

RENAL SYSTEM

   The renal system is immature in young children. Normal urine output is 2 milliliters per kilogram per hour, compared to ½ to 1 ml/kg/hr for adolescents and adults. This indicates that children cannot concentrate urine as well as adults, meaning they cannot conserve fluids as well. Children also have an increased waste-production rate, meaning metabolized drugs will be eliminated more quickly than in an adult.¹ However, this same rate of waste production with a higher urine production rate also predisposes pediatric patients for dehydration.

DRUG ADMINISTRATION

   What do all of these physiological differences mean when considering drug administration? For pediatric patients, it means drugs are administered in smaller, but more frequent doses. Dosages are weight-based in milligrams, micrograms or milliequivalents per kilogram, which allows for much safer drug administration. Thus, as part of your assessment, determine your patient's weight. Often, a parent or legal guardian is the most reliable source for determining weight. When the child's weight is unknown and cannot be reasonably estimated, use a height-based scale to make an estimate.

   The Broselow tape and Pedi-Wheels are excellent tools to estimate patient weight based on age and height. Both also provide calculated dosages for common drugs administered to critically ill pediatric patients. Once the child's weight has been determined, multiply the weight by the dose per kilogram for the drug you need to administer. Pediatric doses for commonly given drugs are listed in the sidebar. If you don't have the doses memorized, be sure to confirm them prior to administration with an accurate source like a drug reference, pocket guide, Broselow tape or online medical control.

RULE OF 6'S

   Most IV drug infusions come in standardized concentrations and are available in premixed bags. However, the need may occasionally arise when a premixed infusion is not available and you need to mix your own. In that case, consider using the rule of 6's to prepare administration of any IV infusions, particularly with vasoactive drugs like dopamine. The rule of 6's has six steps and one multiplication by 6.

1. First, determine the patient's body weight in kilograms. For this example, say the patient weighs 20 kilograms and dopamine is the drug to be administered.
2. Determine the amount of drug needed by multiplying the patient's weight in kilograms by 6 (this 6 is what creates the rule of 6's). For example: 20 times 6 is 120, so you need 120 mg of drug.
3. Mix the quantity of drug determined in Step 2 in a 100mL bag of normal saline or D5W. Label the bag with the name of the drug you added, the quantity and the resulting concentration.
4. Connect a 60-drop infusion set to the mixed bag, so every 1 drop per minute, or 1mL per hour, administered is exactly 1 microgram per kilogram per minute for the patient.
5. Determine the drug dose to be administered. The starting dose for dopamine is 5 micrograms per kilogram per minute. With this mixed infusion set, five drops per minute administers 5 micrograms per kilogram per minute.
6. For each microgram per kilogram per minute increase in drug dose, increase the drip rate by one drop per minute. Remember, each drop per minute equals 1mL per hour.

FLUID ADMINISTRATION

   TKO (to keep open) IVs are not used with pediatric patients. Any time an IV is initiated, use a chart (see Table 2) to determine the fluid rate and the patient's daily fluid intake totals.¹ Isotonic fluids like normal saline are acceptable IV fluids. Pediatric physicians prefer IV fluids containing dextrose, such as D5 in one-half normal saline, for fluid maintenance. When volume resuscitation is required, fluid boluses are determined by administering 20 mL of an isotonic crystalloid per kilogram of body weight.⁴ In addition to any needed fluid bolus, double the infusion rates when dehydration is suspected. If an isolated brain injury is suspected, cut the infusion rate by one-half.

TABLE 2: PEDIATRIC IV FLUID CALCULATION

PEDIATRIC PAIN MANAGEMENT

   Historically, EMTs have been fearful about managing pediatric patient pain. This is unfortunately complicated by failing to assess or underassessing pediatric patient pain, which has led to many myths, including:

• Infants cannot feel pain
• Children experience less pain than adults
• Children will tell you when they feel pain
• Children recover more quickly than adults from pain
• Narcotics are dangerous and always cause respiratory depression in children.

   We now have evidence proving these myths false. Many studies actually show children are more sensitive to pain than adults.⁴ Children do not always, and sometimes cannot, tell their caretakers that they are experiencing pain, yet ill children are at high risk for pain. A few guides have been developed to help identify pain in children. The Wong-Baker faces scale (Figure 1) is a reliable tool to evaluate pain in children older than age 3. Use the scale to ask the child, "Can you show me which face looks like how you are feeling right now?" Observe the child to see which face he or she selects and document the corresponding number beneath each face as the patient's pain level.⁵

   The FLACC scale (Table 3) is an objective way to measure a child's pain when he is unable to verbally tell you the amount of pain he is in. FLACC stands for Face, Legs, Activity, Cry and Consolability. Each component is evaluated and scored 0-2. By totaling each category, the scale gives a score of 0-10, with 10 being the worst pain and zero the least.¹

TABLE 3: FLACC PAIN SCALE

   There are many non-pharmacologic tools available to manage pain. Remember to always document the pain control measures provided. Speak softly to children in a calming tone. Keep lights low and the environment quiet. When using appropriate infant or child passenger restraints, allow the child to find a position of comfort. Appropriately splint all musculoskeletal injuries and apply ice when indicated. Let the child hold his parent's or caregiver's hands whenever practical.

   Pharmacologic pain control begins with oxygen. Administer oxygen via nasal cannula if your patient allows, or have the child hold an oxygen mask to his face, letting him take an active part in his own care. Acetaminophen is a centrally acting analgesic that is safe and easy to administer to children. While it is not yet standard in EMS care, ask your medical director whether or not it may be appropriate to carry acetaminophen for pain management in pediatric patients. Acetaminophen is given in a dose of 10-15 milligrams per kilogram, with noticeable effects usually seen within about 15-20 minutes.⁶ It is available in both tablet and liquid-drop form. Another benefit of acetaminophen is that it can be administered via rectal suppository if there is concern the patient should not have anything by mouth, such as when surgery may be necessary.

   Aggressive pain management is recommended for any wound, fracture or dislocation, and burns.³ Do not ignore pain management. Provide pharmacologic intervention whenever you feel it is necessary based on your patient's presentation. Opioids are a good and acceptable first-line drug for pediatric pain management.¹ Fentanyl and morphine are two commonly administered prehospital pain drugs. Fentanyl is dosed at 1-2 micrograms per kilogram and can be given every 20 minutes. Morphine is administered 0.1-0.2 milligrams per kilogram and can be given every five minutes. Both have side effects. Fentanyl can cause chest rigidity when given too rapidly, and morphine can cause respiratory depression in high doses.

   Following administration of any medication, especially analgesics, careful ongoing monitoring is essential. Pay close attention to the child's pulse oximetry and level of consciousness. It is OK if you see some sedation, but document its presence. Vital signs should be documented at least every 15 minutes, and more frequently for unstable patients and those with mental status changes. As part of vital signs, document the patient's pain level. Use the same pain level assessment technique throughout the entire call. ALS crews should perform cardiac monitoring whenever pharmacologic pain management is utilized.

CONCLUSION

   Administering drugs to pediatric patients is safe when their unique physiological and anatomical differences are considered. Use weight-based dosing to administer smaller, more frequent doses. Also remember that pediatric patients do indeed feel pain, and they deserve the same aggressive pain management as adults. Utilize both pharmacologic and non-pharmacologic techniques when providing pain management.

References

1. Morton PG, Fontaine DK, Hudak CM, Gallo BM. Critical Care Nursing: A Holistic Approach, 8th edition. Lippincott, Williams & Wilkins, Philadelphia, PA, 2005.

2. Bledsoe BE, Benner RW. Critical Care Paramedic, 1st ed. Pearson Education, Inc., Upper Saddle River, NJ, 2006.

3. Hom J. Pediatrics, Sedation. www.emedicine.com/emerg/TOPIC403.htm.

4. American Heart Asssociation PALS Provider Manual, American Heart Association, Dallas, TX, 2006.

5. Hockenberry MJ, Wilson D, Winkelstein ML. Wong's Essentials of Pediatric Nursing 7. Elsevier Mosby, Philadelphia, PA, 2005.

6. Ellsworth AJ, Oliver LM. Mosby's 2007 Medical Drug Reference, Elsevier Mosby, Philadelphia, PA, 2007.

   Kevin T. Collopy, BA, CCEMT-P, NREMT-P, WEMT, is an educator, e-learning content developer and author of numerous articles and textbook chapters. He is also a flight paramedic for Spirit Ministry Medical Transportation in central Wisconsin and a lead instructor for Wilderness Medical Associates. Contact him at kcollopy@colgatealumni.org.

   Greg Friese, MS, NREMT-P, is director of education for CentreLearn Solutions, LLC. He is an educator, instructional designer, author, presenter and podcaster. Connect with Greg on Facebook, Twitter, or e-mail him at gfriese@centrelearn.com.