Clinical Practice Case 5
Case 5
You enter the room of a 3-month-old girl who was brought to the emergency department with a history of vomiting and diarrhea with poor PO intake.
General assessment
You see an infant who appears listless. She is lying on the bed and does not respond to her parents. She is breathing rapidly without retractions or respiratory distress. Her colour appears mottled.
5A
What is your initial impression of the child's condition based on your general assessment?
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This infant has a worrisome clinical picture with tachypnea and decreased response to her parents and her environment. Based on the history of vomiting and diarrhea, she likely had a viral gastroenteritis and now has hypovolemia secondary to fluid loss. The infant's appearance with decreased responsiveness suggests that this infant is in shock.
5B
Does this infant require immediate intervention?
If so, what intervention is indicated?
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yes,
Based on your general assessment, it is appropriate to provide oxygen and call for help to obtain vascular access and get assistance in providing care for this infant.
This infant appears to have an open airway and is breathing adequately, so ventilation is not needed. To obtain more objective data about the infant's condition, you should rapidly proceed to the primary assessment and place the infant on a cardiac monitor and pulse oximeter. Once vascular access is established, begin rapid fluid resuscitation.
Primary assessment
You administer high-flow oxygen and proceed with your primary assessment. The child's heart rate is 210/min, respiratory rate is 50/min, blood pressure is 60/43 mm Hg, and the axillary temperature is 97 0F (36.1 °C). The pulse oximeter is not picking up the pulse consistently-when a reading is obtained it is 99% to 100%. You palpate weak brachial and femoral pulses, but you cannot palpate distal pulses. Heart sounds are normal. The extremities are cool and mottled below the elbows and knees. Capillary refill time in the foot is >5 seconds. Auscultation reveals clear lungs with good distal air entry bilaterally. During the examination, the child moans occasionally but otherwise has little response to verbal or painful stimulation.
5C
How would you categorize this infant's condition?
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The vital signs confirm your initial clinical impression that the infant is in shock.
Is the infant hypotensive?
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Lower limits of systolic blood pressures that are considered to define hypotension are
- <60 mm Hg in infants during the first month of life
- <70 mm Hg for infants from 1 month to 12 months of age
- <70 mm Hg + (2 x age in years) for children from 1 to 10 years of age
If a blood pressure measurement device is not readily available, the absence of detectable distal pulses is consistent with hypotensive shock. Indeed, if peripheral pulses are difficult to palpate, you should interpret the results of automated blood pressure devices cautiously because they are not highly reliable in this situation. The failure of a pulse oximeter to detect the pulse when placed on the extremities should raise your concern that the child has poor distal perfusion and is in shock.
5D
What decisions and actions are appropriate at this time?
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Since this infant is in hypotensive shock, you must quickly establish vascular access to enable administration of one or more isotonic crystalloid fluid boluses. Brief attempts to gain peripheral venous access are appropriate. But if they are not rapidly successful, then place an IO needle because the infant is in hypotensive shock.
Laboratory studies will be helpful to objectively determine the severity of shock. You should obtain a bedside glucose determination as soon as possible because infants in shock are at high risk for hypoglycemia.
5E
What is the definition of shock?
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Shock is a clinical condition in which tissue perfusion is inadequate to meet metabolic demand. In this infant global cardiac output is apparently reduced, but remember that in some forms of shock, cardiac output may be increased (e.g. septic shock).
5F
What elements of the secondary assessment would you like to know?
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Obtain a focused history while you implement the above interventions. The duration of the child's symptoms, allergies, use of any medications, past medical history, fast, feeding, and any events leading up to the infant's presentation are important history elements. The infant most likely has a viral gastroenteritis based on the history, but you should carefully look for the presence of signs suggesting a different cause, such as sepsis. Look for the presence of a skin rash or bruising. Assess the abdomen (ie, is the abdomen distended and tender?) for signs of a potential surgical problem, such as an acute abdomen.
Your colleagues try to establish vascular access while you obtain additional history information.
The infant's parents report her signs and symptoms:
she has had "nearly continuous vomiting and diarrhea" during the previous 8 hours. They are uncertain if she has urinated during this time because her diapers have been filled with watery diarrhea. She has no allergies and is not receiving any medications. Her past medical history is unremarkable. She took an ounce of fluid about an hour ago (last meal). Events leading to the presentation are as follows:
The infant was well until yesterday when she initially started having episodes of vomiting and then a few hours later began having watery diarrhea. Her vomiting is better, but she is not taking clear liquids well and her diarrhea is worse today. There is no history of fever, and no one else in the family is ill.
The infant has reduced skin turgor without skin rash except for erythema of the diaper area. The abdomen is soft with the liver at the costal margin. Her fontanel is sunken.
Initial attempts at establishing IV access are unsuccessful.
5G
What would you do now?
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In this infant with hypotensive shock, it is inappropriate to make multiple attempts to insert a peripheral IV catheter. A highly skilled provider may elect to attempt central venous catheter placement, but the most appropriate next step for most providers is to place an IO catheter.
5H
After vascular access is obtained, what fluid and how much would you give?
How quickly should you administer the fluid bolus?
What bedside laboratory test is critically important?
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As soon as the needle is placed, you should deliver 20 ml/kg of isotonic crystalloid, such as normal saline. Remember to use a 3- way stopcock or pressure bag to rapidly deliver the fluid since it will generally not flow rapidly through a small peripheral IV or I0 needle.
The fluid should be given as rapidly as feasible, ideally over less than 15 minutes.
If blood is aspirated at the time the 10 access is confirmed, you should perform a bedside glucose determination.
Case progression
The bedside glucose is 40 mg/dL. You give an initial fluid bolus of isotonic crystalloid (20 mL/kg over about 10 minutes) and a bolus of 25% dextrose (0.5 gm/kg). You reassess the infant: heart rate is 195/min to 200/min, respiratory rate remains at 50/min, blood pressure is 66/42 mm Hg, and pulse oximetry reveals Sp02 of 100%. The infant appears a bit more responsive, but the distal pulses are still not palpable. Capillary refill remains prolonged.
5I
What are your decisions and actions now?
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When you reassess the infant, she is slightly improved, but she remains very tachycardic and her distal pulses are still not palpable. These findings indicate that another isotonic crystalloid fluid bolus is indicated.
5J
What additional tertiary studies would you like to obtain?
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The following tertiary studies may help assess the severity of acidosis and the presence of hyponatremia or hypernatremia:
- Blood sample to evaluate serum electrolytes
- Repeat bedside glucose test
- Complete blood count will help determine if the infant is anemic, and the white blood cell count may help identify if the infant is at increased risk of bacterial sepsis (either a high or low white blood cell count); it will also confirm whether the infant has adequate oxygencarrying capacity (ie, hemoglobin concentration)
- Blood and urine cultures if sepsis is considered a risk based on the history and examination
- Urine analysis
It is helpful to place a bladder catheter both to monitor the volume of urine produced and to obtain a urine sample for analysis. Remember that the initial volume of urine in the bladder does not determine the current urine output since you don't know how long the urine has been in the bladder. An indwelling bladder catheter will permit ongoing assessment of urine production, which provides indirect evidence of the effectiveness of renal perfusion.
Case progression
The infant receives additional fluid. The infant appears more responsive after the subsequent fluid with heart rate down to 180/min. Distal pulses are now palpable. The pulse oximeter currently shows a consistent waveform on the monitor. A catheter is inserted into the bladder, and 30 mL of dark yellow urine is obtained. The infants' initial laboratory studies were as follows: sodium 136 mEq/L, potassium 3.9 mEq/L, chloride 110 mEq/L, total CO2 11 mEq/L, BUN 29 mg/dL, creatinine 0.9 mg/dL, and lactate is 4.4 mmol/L. White blood cell count is 7,600/mm3 with a normal differential, hemoglobin is 10.9 g%, hematocrit is 32.5%, and platelet count is 335,000mm3. Repeat rapid bedside glucose is 50 mg/dL.
5K
How does the laboratory data and urine output help you categorize this infant's condition?
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The infant's normal white blood cell count and platelet count suggests that the infant does not have bacterial sepsis. The hemoglobin concentration is adequate, so the infant is not anemic.
The advanced care provider will calculate the anion gap at 23 mEq/L (including potassium in the calculation); this is an elevated anion gap. It is, however, not as wide as expected by the child's clinical condition. The chloride is relatively high and the bicarbonate is low. It is likely that this infant has a mixed anion gap and non-anion gap acidosis with the latter caused by the loss of bicarbonate in watery diarrhea. This is important to recognize since it will be more difficult to correct the metabolic acidosis without the administration of bicarbonate or a substance that can be readily converted to bicarbonate (eg, acetate). Thus, some advanced providers may change the child's IV fluid to use potassium acetate rather than potassium chloride in this setting. There are different approaches that may be used in this situation, such as adding sodium bicarbonate to half-normal saline or using potassium acetate in the IV maintenance fluids.
5L
What are your decisions and actions now?
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The glucose concentration remains low, so you should administer another bolus of glucose and begin a maintenance of glucose infusion. The electrolytes show that the infant's serum sodium concentration is normal, so administration of an isotonic IV fluid such as normal saline or lactated Ringer's solution is appropriate.
Case conclusion
The infant is placed on IV replacement and maintenance fluids of dextrose in normal saline with 20 mEqlL of potassium chloride. She is now much more vigorous with palpable distal pulses, so she is admitted to the pediatric ward for further therapy. This infant demonstrated the clinical history and signs of hypovolemic shock, the most common type of shock in infants and children. The clinical signs are tachycardia, quiet tachypnea, a narrow pulse pressure with cool extremities, prolonged capillary refill, and weak distal pulses. Changes in the level of consciousness depend on the severity of hypovolemia. Depressed level of consciousness is a relatively late manifestation of hypovolemic shock because in infants and children intense vasoconstriction may initially maintain perfusion to the brain and heart.