Clinical Practice Case 8
Case 8
You are called to see a 15-year-old patient on the pediatric ward who has developed an acute onset of respiratory distress and chest pain. He was admitted 3 days earlier after being struck by a car. His injuries include a fracture of his left femur and multiple contusions and abrasions. His femur fracture was stabilized with external fixation. He was doing well on the ward until he complained of shortness of breath.
General Assessment
As you enter the room you see an adolescent who appears anxious. He has obvious tachypnea and appears diaphoretic. He is alert with mottled skin colour.
8A
What is your initial impression of the child's condition based on your general assessment? Are any interventions required at this time? If so, what are they?
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The child has signs of respiratory distress with obvious anxiety and mottled skin. The mottled skin may be caused by shock or poor oxygenation. It is difficult to tell through visual observation, but his alert mental state suggests that he is still perfusing his brain adequately and that his Sp02 is not too low.
At the least, you need to call for help, activate the emergency response system, start oxygen, and place him on a cardiac monitor and pulse oximeter while you continue with your primary assessment.
Primary Assessment
His respiratory rate is 32/min with somewhat deep respirations and mild retractions. Heart rate is 135/min with thready distal pulses and weak central pulses.
You attach a cardiac monitor, which displays a regular sinus rhythm with no arrhythmias. His blood pressure is 88/62 mm Hg by the automated cuff. Temperature is 37.7°C, and pulse oximetry shows Sp02 of 92% on room air. There are scattered wheezes and a few moist crackles noted with a rapid regular rhythm. His skin is cool and clammy without rash. He is alert and obviously anxious; he answers questions appropriately and tells you that he does not feel well.
8B
How do you categorize this patient's condition? What do you think is causing this patient's respiratory distress?
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He has clinical signs of respiratory distress with hypoxemia and signs of shock with poor perfusion. The sudden onset of this combination of signs and symptoms suggests an acute process that is affecting both his circulatory and pulmonary function.
Although pneumonia is possible, the sudden onset is not typical of pneumonia. Instead, this combination of findings in a patient who is immobilized in bed following a femur fracture is most consistent with a pulmonary embolus.
8C
What are your decisions and actions now?
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A new PALS provider may not be familiar with an acute pulmonary embolism. It is a relatively uncommon condition in children that may be under-recognized. It causes an acute, variable reduction in cardiac output due to the obstruction of blood flow going from the right heart to the pulmonary circulation and ultimately to the left heart. The magnitude of obstruction depends on the size of the embolus. Intrapulmonary shunting and resultant hypoxemia are also common, but adequate ventilation, as documented by arterial PCO2, is usually maintained.
In this form of obstructive shock, the treatment depends on the severity of symptoms. Often the patient will respond to an increase in preload (i.e, a fluid bolus.
Therapy designed to dissolve the clot may be used (i.e, thrombolytic therapy, but it is associated with higher risk of hemorrhage when the patient has had recent surgery or trauma (as in this child). Instead, treatment is often supportive, consisting of bolus fluid therapy and the acute administration of heparin designed to prevent further clot formation.
Case Progression
In response to high-flow oxygen administration by a nonrebreathing mask (nearly 100% oxygen), the patient remains in distress and anxious. His Sp02 increases to 98% and heart rate 130/min. The respiratory rate remains increased at approximately 30/min. After he receives 10 mL/kg of normal saline IV, his blood pressure is 90/65 mm Hg with weak but improved distal pulses. He tells you the following when you ask him for more details about not feeling well:
- He says he feels as if he can't breathe but has no pain with breathing; he says he feels scared (signs and symptoms).
- He is not allergic to any medications.
- He is receiving codeine and acetaminophen for pain (medications).
- The rest of his past medical history is unremarkable.
- He ate lunch about an hour ago.
- He reports that the onset of respiratory distress was sudden and that he had been breathing OK prior to this event.
His abdomen is soft with his liver about 1 cm below the right costal margin
His neck veins are somewhat distended
8D
What would you do now? What laboratory and nonlaboratory studies would help you determine the cause of this patient's condition and necessary treatment?
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The patient responded to 10 mL/kg of isotonic crystalloid with some improvement in his clinical condition, so administration of another small fluid bolus would be appropriate.
An arterial blood gas would help the experienced provider determine the degree of ventilation-perfusion mismatch and the degree of metabolic acidosis, which would help quantify the magnitude of the compromise in tissue perfusion. A chest x-ray would be appropriate to rule out pneumonia and to evaluate the patient's heart size.
An echocardiogram can help identify the presence of a pulmonary embolism by showing increased volume in the right ventricle and atrium and decreased blood volume in the left ventricle. An echocardiogram also helps rule out the presence of a pericardial effusion. To confirm the diagnosis of a pulmonary embolism, the most common diagnostic test is a spiral CT scan with IV contrast.
8E
What conditions may cause this type of shock?
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The 3 common causes of obstructive shock are pulmonary embolism, pericardial tamponade, and tension pneumothorax. All 3 are characterized by an obstruction of blood flow. Pulmonary embolism causes the right heart to be distended because the obstruction is in the pulmonary artery; the other 2 causes result in impaired filling of the right and left ventricle, so the heart will appear small on echocardiogram.
With pericardial tamponade, the heart size may be normal or enlarged on chest x-ray. The chest x-ray is also helpful in confirming the diagnosis of a tension pneumothorax. Ideally, the PALS provider should suspect and treat tension pneumothorax based on clinical exam rather than await radiographic confirmation.
A less common cause of obstructive shock is seen in neonates with some congenital heart lesions. Neonates with a congenital cardiovascular obstruction, such as severe coarctation of the aorta, may present clinically when the patent ductus arteriosus begins to close, usually within the first 2 weeks of life.
Case Progression
An arterial blood gas obtained while the patient is receiving 100% high-flow oxygen by nonrebreathing mask shows: pH 7.37, PC02 34, P02 277, base deficit - 5.8, bicarbonate 17.5 mmo/lL, lactate 3.2 mmol/L. Glucose is 178 mg/dL. His WBC count is 11,600 with a normal differential, hemoglobin is 12.2 g/dL, and platelet count is 233,000/mm3.
A chest x-ray shows a hazy infiltrate in the right lower lobe area; heart size appears mildly enlarged. In response to a second fluid bolus, his perfusion is better. An echocardiogram shows a distended right ventricle and an underfilled left ventricle with increased left ventricular contractility.
Case Conclusion
The child's diagnosis of a pulmonary embolism is confirmed by a high-resolution CT scan. Treatment consists of heparin administration since he is not hemodynamically unstable after his fluid resuscitation.
