Clinical Practice Case 6
Case 6
A mother brings her 4-year-old girl to the pediatrician's office. The child has a history of increasing lethargy, fever, and "dizziness" when she tries to stand up. There is no history of vomiting or diarrhea. Her intake has been poor over the last 12 hours. Typical chickenpox lesions developed 5 days ago. Over the last 18 hours, several lesions on her abdomen have become red, tender, and swollen.
General assessment
As you enter the room to obtain the child's vital signs, you note that the child is lying supine and appears listless. She is breathing rapidly and quietly. Her skin is mottled.
6 A
What is your initial impression of the child's condition based on your general assessment? Does the child need immediate intervention? If so, what intervention is indicated?
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This child's appearance is very worrisome because she demonstrates a decreased response to her environment. Her history of chickenpox with these clinical changes suggests sepsis since the skin rash in children with chickenpox provides a portal for bacterial superinfection.
Once septic shock is considered, it is important to activate the appropriate emergency response system to obtain additional help in treating shock and stabilizing the child.
In the short term, this child appears to be breathing adequately, but oxygen should be administered in all children with shock to maximize oxygen delivery to the tissues. For any child with possible sepsis or septic shock, you should:
- complete your primary assessment
- direct appropriate help to place the child on a cardiac monitor and pulse oximeter
- establish vascular access
- administer rapid fluid bolus with isotonic crystalloid (eg, normal saline or lactated Ringer's)
- conduct clinical reassessment
While you complete your primary and secondary assessments, other providers can obtain appropriate laboratory studies, including a rapid bedside glucose test and blood cultures.
Primary Assessment
After calling for help and administering high-flow oxygen, you begin to obtain vital signs and attach a pulse oximeter and cardiac monitor. You note that the child is confused. She responds to your voice and tries to answer questions, but she does not know where she is and does not seem to understand what people are saying.
Her heart rate is 165/min, respiratory rate is 60/min, rectal temperature is 39.4°C (103°F), and blood pressure is 90/30 mm Hg. Auscultation reveals clear lungs with good distal air entry. You hear a regular, rapid heartbeat with a short systolic ejection murmur. Extremities are warm and bright red; central pulses are full and bounding, and peripheral pulses are palpable but feel thready. The skin is warm to mid forearms and mid calves. Capillary refill is about 2 seconds. The skin lesions on her abdomen are bright red and tender. Pulse oximetry shows Sp02 of 100% while the child is receiving the high-flow oxygen.
6 B
How do you categorize the child's condition? What decisions and actions are indicated now?
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The child has significant tachycardia with adequate distal perfusion and an acceptable (low normal) systolic blood pressure on examination. These findings are consistent with compensated septic shock.
As soon as vascular access is established, administer a rapid fluid bolus with isotonic crystalloid (e.g, normal saline or lactated Ringer's) followed by clinical reassessment.
6 C
What is the significance of the pulse pressure and the elevated respiratory rate?
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One of the characteristics of sepsis is a wide pulse pressure. (The pulse pressure is the difference between the systolic and diastolic blood pressures.
The advanced provider will remember that if the diastolic blood pressure is less than or equal to half of the systolic blood pressure, the pulse pressure is clearly increased or widened. This is a finding consistent with a reduced systemic vascular resistance. The most likely cause of this vasodilated state is sepsis.
The child is tachypneic without increased work of breathing. This is characteristic of shock with the increased respiratory rate representing a compensatory response to create a respiratory alkalosis to counteract the metabolic acidosis that characterizes shock.
6 D
What other conditions result in a wide pulse pressure?
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In addition to sepsis, a wide pulse pressure is seen in children with spinal (neurogenic) and anaphylactic shock. A wide pulse pressure is also seen in children with significant anemia, such as the child with sickle cell anemia, and in children with high fever, especially when the temperature is coming down (i.e, when they are vasodilated as they attempt to eliminate heat).
In both situations, the vasodilation represents the need for low systemic vascular resistance to maintain a high cardiac output state. In sepsis, the vasodilation results from the effects of the inflammatory mediators. With anemia, the reduced oxygen-carrying capacity and oxygen content are compensated by a high cardiac output to maintain tissue oxygen delivery. Similarly, the increased metabolic demand produced by fever requires a high cardiac output to maintain adequate oxygen delivery.
Other less common clinical conditions that cause a vasodilated state occur in children with chronic or acute liver failure and thyrotoxicosis.
6 E
What additional assessment studies are indicated?
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During the secondary assessment, you should look for evidence of cardiac dysfunction (listen for a gallop, assess the hepatic size, and look for venous distention in neck veins). Also look for evidence of purpura and petechia suggestive of disseminated intravascular coagulation or other coagulopathies that can complicate sepsis. During the focused history obtain any further information about the child (SAMPLE), including:
- the child's recent signs and symptoms
- if the child has any allergies to the antibiotics that you plan to administer
- if the child is receiving any medications
- if the child's past medical history is relevant to her current condition
- the time of the child's last meal in anticipation of the need for intubation
- additional details about this event or the most recent change in responsiveness.
A bedside glucose test is important because children with sepsis are at increased risk for hypoglycemia. Blood samples for other studies,
such as electrolytes and blood counts (tertiary assessment), will provide additional information to help you determine the severity of shock and identify the etiology as well as identify complications resulting from shock or its cause.
Advanced providers will find it helpful to obtain an arterial or venous blood gas and measurement of serum lactate concentration. These results will help objectively determine the severity of shock. (These results are discussed further in the case presentation.) It is unlikely that arterial blood gases will be available in the physician's office, however.
Case Progression
After vascular access is obtained, you administer an isotonic crystalloid fluid bolus (20 mL/kg). Your repeat assessment reveals a heart rate of 155/min, respiratory rate is still approximately 60/min, and blood pressure is 85/30 mm Hg. You can still palpate weak distal pulses with capillary refill
- Her mother reports that the child's dizziness started about an hour ago (signs and symptoms).
- There is no history of allergies. She received acetaminophen for fever and is not receiving other medications.
- The child was healthy up until this recent illness with chickenpox (past medical history and events leading to presentation).
6 F
What would you do now?
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The repeat assessment shows a slight improvement in the child's heart rate. Monitoring the change in heart rate is an important element of shock assessment. If the correct interventions are provided and are effective, the heart rate and systemic perfusion will improve.
The child remains quite tachypneic, and the pulse pressure is still wide with a fall in the systolic blood pressure. It is important to recognize that sepsis is a dynamic clinical state and that frequent reassessment and aggressive fluid resuscitation are commonly required. Therefore, this child requires another rapid fluid bolus with isotonic crystalloid (e.g, normal saline or lactated Ringer's) followed by clinical reassessment. If available, administer appropriate antibiotics.
In this patient staphylococcal sepsis is possible because the skin is the likely source for the infection. The advanced provider will know that vancomycin is appropriate in view of the increasing frequency of methicillin-resistant Staphylococcus aureus.
This child requires urgent transport as soon as possible to the nearest tertiary care centre with pediatric critical care capability.
Case Progression
You begin to administer a second isotonic crystalloid bolus. You perform a bedside glucose test in the office that reveals a glucose concentration of 140 mg/dL. EMS providers arrive and transport the child to the emergency department of the nearest healthcare facility. In response to the second fluid bolus, the child becomes more alert. In the emergency department blood cultures are obtained, and IV antibiotics are given along with another 20 mL/kg bolus of normal saline (total of 60 mL/kg normal saline administered in an hour).
Despite the fluid boluses the child's condition deteriorates. She becomes unresponsive to voice and barely responsive to painful stimulation. Her distal pulses are no longer palpable. Her extremities are cold. Her heart rate ranges from 170/min to 180/min, and her blood pressure decreases to 70/25 mm Hg. She remains tachypneic on a nonrebreathing oxygen mask. Her lung fields are clear, but pulse oximetry is not picking up her pulse accurately.
6 G
How would you categorize the child's condition now? What decisions and actions are indicated?
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Despite a total of 60 mL/kg administered in 3 fluid boluses in less than an hour, this child's systolic blood pressure indicates that she has a hypotensive shock that is fluid refractory.
Based on the PALS Management of Septic Shock Algorithm, she requires vasoactive drug support.
If possible, providers should establish a central venous line to safely administer a potent vasoconstrictor such as norepinephrine, high-dose dopamine, or vasopressin. If a central venous line cannot be established, a secure peripheral venous line or I0 line may be used. This requires a second access site because fluid boluses should not be given through the same site as the vasoactive drug infusion.
Questions 6H through 6K and responses are intended for advanced providers.
6 H
Why is she deteriorating despite fluid administration?
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The child has vasodilated septic shock. Severe septic shock is a complex physiologic state with hypotension typically resulting from a combination of profound arterial and venous vasodilation combined with variable impairment of cardiac contractility and increased capillary permeability.
The veno-dilation results in pooling of blood in the venous circulation with a reduced venous return to the heart and therefore reduced cardiac output.
Impaired cardiac contractility may reduce the ejection fraction, contributing to a fall in cardiac output. Increased capillary permeability contributes to the relative hypovolemia despite fluid administration.
Sepsis is a form of distributive shock because it is characterized by a maldistribution of blood flow. There is often excessive blood flow to the skeletal muscle and inadequate blood flow to the intestines, liver, and kidney.
6 I
When would you add vasoactive drug support?
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If the patient does not adequately respond to aggressive fluid resuscitation, you should administer vasoactive drugs. Potent vasoconstrictor agents may be helpful to maintain effective perfusion of the brain and heart and to reduce the excessive skeletal muscle flow and redirect blood flow to the splanchnic circulation.
6 J
What are the indications for giving "stress-dose" corticosteroids?
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If the child requires potent vasoactive agents, many experts now recommend the addition of a stress-dose of hydrocortisone.
Note that this is a small dose of steroids compared with the larger doses that were used in the treatment of sepsis in years past-typically only 2 mg/kg of hydrocortisone is given as a loading dose.
Some experts recommend obtaining a blood sample to determine cortisol concentration or performing an ACTH stimulation test before administration of hydrocortisone. Because many labs do not have a sufficiently rapid turnaround on cortisol concentrations, hydrocortisone may be started empirically.
6 K
When would you intubate this child and provide mechanical ventilation? Are there any special risks of the intubation procedure in this patient?
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The decision to intubate and place the child on mechanical ventilation requires that you weigh the need to maintain good oxygenation and ventilation and reduce the metabolic demand from the work of breathing against the potential detrimental effects of positive-pressure ventilation on intrathoracic pressure and potential reduction in venous return and cardiac output.
Moreover, sedative agents are typically needed to permit endotracheal intubation, but these agents may reduce the child's endogenous stress hormone response and result in sudden cardiovascular collapse. You may not realize how much the child depends on her intrinsic catecholamine response until a sedative agent is given.
Thus it is important that you provide adequate fluid resuscitation and, if possible, begin a vasopressor drug infusion (eg, norepinephrine, epinephrine, or dopamine) before intubation. Sedative agents should be titrated by giving small doses to achieve just the level of sedation required for intubation.
Case Conclusion
A central line is placed and vasoactive drug support is initiated. The child's blood pressure improves to 90/36 mm Hg with better distal perfusion. An arterial catheter is also placed for continuous blood pressure monitoring. She is receiving 40% oxygen by face mask. An arterial blood gas shows the following: pH 7.37, PCO2 32, P02 245, base deficit - 5.5; a venous blood gas from the central venous cannula had a P02 of 42 mm Hg with oxygen saturation of 78%. Lactate was 3.3 mmol/L. The laboratory values show that oxygen extraction by the tissues is normal to reduced, which is typical in septic shock patients with adequate fluid resuscitation.
6 L
Can you give vasoactive drugs through a peripheral IV catheter?
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Although the peripheral venous administration is not ideal when the child has fluid-refractory shock, vasoactive drug support may be given through a peripheral venous catheter or I0 catheter. You should closely monitor the vascular infusion site to detect early signs of infiltration. You should infuse vasoactive medications through a central line when one is inserted.
As a detail for the advanced provider, when a central venous infusion site is established after beginning a peripheral venous vasoactive drug infusion, it is often preferable to start a second vasoactive infusion through the central line and then stop the peripheral infusion when additional drug effect is seen. If you simply switch the infusion tubing from the peripheral to a central line, the patient's blood pressure may rapidly fall because whenever a vasoactive infusion is added to an infusion catheter, it will take several minutes for the vasoactive infusion to infuse through the tubing to reach the patient.
6 M
In addition to sepsis, what are other causes of distributive shock?
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Distributive shock is characterized by a maldistribution of blood flow due to inappropriate vasodilation. The latter is clinically characterized by a wide pulse pressure, as previously noted, and some evidence of organ ischemia.
In addition to sepsis, the distributive shock is seen in children with profound anemia, such as a child with new-onset leukemia, who may present with a hemoglobin as low as 3 g/dL or lower. In this case, even though the cardiac output is high, the low hemoglobin concentration reduces arterial oxygen content, so there is inadequate oxygen delivery to the tissues, leading to anaerobic metabolism and defining shock.
Distributive shock may also be seen in a child with spinal cord injury interrupting the sympathetic innervation to the vasculature, resulting in profound vasodilation and hypotension (also called "spinal shock").
Anaphylaxis may also produce histamine release that causes profound vasodilation and hypotension. The cardiac output in anaphylaxis is also compromised by an elevation of pulmonary vascular resistance, which may cause acute right heart strain and impaired delivery of blood from the right heart through the pulmonary circulation and to the left ventricle.
Case Summary
This child had septic shock complicating varicella (chickenpox) infection. This is commonly caused by streptococci or staphylococci. The clinical course may be complicated by the toxin release from these organisms, leading to a greater risk of hemodynamic instability and organ injury. The key to a successful outcome from septic shock is early recognition and aggressive early fluid resuscitation (typically 60 to 80 mL/kg in the first hour and 240 mL/kg in the first 8 hours of therapy in children with shock) with frequent reassessment. Early activation of the EMS system and transfer of the patient to a centre with expertise in the management of pediatric septic shock are also important.