Clinical Practice Case 4
Case 4
An 11-year-old boy is in the intermediate care unit pending surgical resection of a newly diagnosed brain tumor in the morning. He presented to the emergency department earlier today with vomiting and double vision. A CT scan revealed the diagnosis. He was treated with steroids and admitted to the hospital and was clinically improved several hours later. You are called to his room the night before surgery because his mother is concerned that the boy is demonstrating what she describes as "funny breathing."
General assessment
You see a somnolent adolescent who has his eyes closed and does not respond as you enter the room. His breathing is characterized by periods of several slow, deep breaths followed by pauses. His colour appears pale.
4A
What is your initial impression based on your general assessment?
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This child's clinical condition is very worrisome because the respiratory pauses indicate disordered control of breathing.
4B
Does the child require immediate intervention?
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In view of his history, you have to be concerned about increased intracranial pressure or some other neurologic emergency (eg, subclinical seizures or a postictal state from an unobserved seizure). You should immediately activate the emergency response team, shout for help if necessary.
If so, what intervention is appropriate at this time?
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Begin mask ventilation with oxygen. Ask a colleague to place the patient on a cardiac monitor and pulse oximeter.
You should anticipate the need for airway intervention.
Primary assessment
You note that the patient intermittently makes an inspiratory effort, but there does not appear to be air movement with these efforts. He has suprasternal retractions. His heart rate is irregular and averages around 60/min. His respiratory rate is around 12/min but is irregular as noted. You hear intermittent transmitted upper airway inspiratory snoring sounds. His lung sounds are otherwise unremarkable. His radial pulse is readily palpable. Capillary refill is brisk. Heart sounds are normal. You firmly pinch his finger, which results in grimacing and rigid extension of his arms and legs. His pupils are 4 to 5 mm in diameter and appear to be sluggishly reactive to a bright light. Blood pressure is 135/90 mm Hg. A pulse oximeter reveals a Sp02 that fluctuates between 88% and 98% on room air.
4C
How would you categorize this child's condition?
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This child demonstrates disordered control of breathing characterized by intermittent pauses in ventilation. In addition, the child has decreased responsiveness and decreased upper airway tone, resulting in intermittent upper airway obstruction. Hypoventilation is present and is likely causing hypercarbia and hypoxia.
4D
What decisions and actions are appropriate at this time?
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In this patient the major concern is that the hypercarbia and hypoxia are further increasing his intracranial pressure, resulting in impending brain herniation. Noxious stimulation caused decerebrate (i.e. extensor) posturing. Since either hypercarbia or hypoxemia can contribute to increased intracranial pressure, you should attempt to correct both. He also has a relatively slow and irregular heart rate with increased blood pressure, both of which are consistent with increased intracranial pressure and impending herniation. This represents an emergent condition requiring immediate intervention.
Appropriate interventions include initiation of ventilation with oxygen. You should be using a bag-mask device with oxygen. Your goal is to provide modest hyperventilation to help acutely reduce the Paco2, and raise the Pao, to reduce intracranial pressure (ICP). Note that hyperventilation is discouraged for routine ventilation of patients with cardiopulmonary failure or brain injury. Hyperventilation, however, is appropriate when there are signs of impending cerebral (brain or brainstem) herniation, as in this patient. Inadequate or abnormal central control of respiratory drive is a cause of respiratory failure that may not present with symptoms of respiratory distress but still can result in respiratory failure. Because there is no respiratory distress, it sometimes is more difficult to recognize that the patient requires urgent intervention.
You will also improve ventilation by properly opening the child's airway. He is unresponsive, so his tongue is probably causing upper airway obstruction. IV administration of either mannitol or 3% normal saline would be appropriate to help reduce ICP acutely. If necessary an oropharyngeal airway may be inserted, provided the child remains poorly responsive to stimulation and has no cough or gag reflex.
In response to bag-mask ventilation with 100% oxygen, the patient begins to resist intervention and reaches up to push away your hands holding the mask to his face. His Sp02 is 100%.
4E
Should you stop providing bag-mask ventilation?
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No, you should continue providing assisted ventilation. The patient's initial improvement in neurologic status likely reflects the effectiveness of your ventilation in reducing his increased intracranial pressure.
Should you intubate this patient?
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Yes, you should proceed with insertion of an advanced airway.
4F
If you decide to intubate, what are important considerations in planning to intubate this child?
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You should use medications to help reduce intracranial pressure during endotracheal intubation. It is important to ensure that all of the necessary equipment is present before you begin the procedure. The provider who is most skilled in endotracheal intubation should perform or closely supervise the intubation procedure. We recognize that teaching institutions have an obligation to provide experience and education to help new providers learn essential skills.
Case progression
The child receives bag-mask ventilation, and his Sp02 is 100% by pulse oximetry. The most experienced healthcare provider successfully intubates the child's trachea with a 6.5 mm cuffed tracheal tube using a rapid sequence technique.
Tube position in the trachea is confirmed by clinical examination and detection of exhaled C02. The child's heart rate is 88/min and blood pressure is 110/65 mm Hg following endotracheal intubation and mild hyperventilation. A chest x-ray is ordered to confirm the depth of tube insertion. He is ventilated at 20 breaths per minute. A post-intubation arterial blood gas shows: pH 7.49, Pco, 30, P02589, base excess + 0.2. End-tidal CO2 by capnography is 28 mm Hg.
A more detailed history is obtained. He was doing well in the evening until he got sleepy. His breathing changed while he slept. He has no allergies. His only medications are dexamethasone and ranitidine. His past medical history was unremarkable. His last meal was lunch (more than 6 hours ago). There are no additional relevant details about this most recent breathing event. The mother did not observe any seizure activity prior to the change in breathing.
4G
What are the next appropriate steps?
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The next steps are to use the clinical assessment and exhaled CO2 detection to confirm endotracheal tube placement. The tube should be secured in place. Confirm the correct depth of tube position with clinical assessment and by chest x-ray. Record the endotracheal tube depth marker (usually in centimetres) that sits at the lip or teeth when the tube position is confirmed. Since many of the agents used to facilitate endotracheal intubation are short-acting, the patient should receive additional sedation agents to maintain sedation and thus help reduce intracranial pressure.
Case conclusion
The child is transported to the CT scanner with continuous ECG, exhaled CO2, and pulse oximetry monitoring. His CT scan shows new bleeding in his tumor with increased edema surrounding the tumor. He is rapidly transported to the operating room for tumor resection.
This child had respiratory failure secondary to the disordered control of breathing. In general, treatment of this condition requires the immediate bag-mask support of oxygenation and ventilation followed by endotracheal intubation and mechanical ventilation.
4H
In addition to increased intracranial pressure, what other conditions can cause disordered control of breathing?
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Other conditions include drug overdose, metabolic conditions causing coma (e.g. hyperammonemia), head trauma, subclinical seizures, or vascular events such as stroke or subarachnoid hemorrhage.
Summing up
Causes and Presentation of Respiratory Failure or Arrest
In summary, there are 4 general types of respiratory problems leading to respiratory failure or arrest, as illustrated in the previous cases:
- Upper airway obstruction
- Lower airway obstruction
- Lung tissue (parenchymal) disease
- Disordered control of breathing
These are recognized by specific signs and symptoms.
Upper Airway Obstruction
The major clinical signs of upper airway obstruction occurring during the inspiratory phase of the respiratory cycle. The child may have stridor, hoarseness, or a change in voice or cry. There are inspiratory retractions, use of accessory muscles, and nasal flaring. The respiratory rate is often only mildly or moderately elevated because rapid respiratory rates tend to increase the relative severity of the upper airway obstruction.
Lower Airway Obstruction
The major clinical signs of lower airway obstruction occur during the expiratory phase of the respiratory cycle. The child often has wheezing and a prolonged expiratory phase requiring increased expiratory effort. The respiratory rate is usually elevated, particularly in infants whose respiratory rates commonly exceed 60/min. When lower airway obstruction impairs both inspiration and exhalation, increased inspiratory effort is required, and it will produce prominent inspiratory retractions.
Lung Tissue (Parenchymal) Disease
With lung tissue (parenchymal) disease, the child's lungs become stiff, requiring increased respiratory effort during inspiration. Therefore retractions and increased respiratory effort are common. Hypoxemia is often marked. It can be caused by alveolar collapse or pulmonary edema fluid and inflammatory debris in alveoli that reduces oxygen diffusion, or both. Tachypnea is common and often quite marked. The patient frequently tries to counteract alveolar and small airway collapse by increased efforts to maintain an elevated end-expiratory pressure; this is usually manifested by grunting respirations.
Disordered Control of Breathing
In disordered control of breathing, the breathing pattern is abnormal. Often the parent will state that the child is "breathing funny." There may be periods of increased rate or effort followed by decreased rate or effort, including respiratory pauses (apnea), or the child's respiratory rate and/or effort may be continuously inadequate. The net effect is hypoventilation. This clinical state results from a host of conditions such as injury to the brain or brainstem, or both, or drug overdose.
