Understand how monitoring tools can be used to guide treatment for COPD exacerbations
By Bob Sullivan
Chronic obstructive pulmonary disease affects approximately 32 million Americans, and it is the fourth leading cause of death in the United States. COPD includes a group of degenerative conditions that impair airflow through the lungs. Cigarette smoking is the most common cause of COPD, and chronic bronchitis and emphysema are the two main types .
COPD exacerbations are frequently encountered by EMS providers, and proper assessment and treatment can significantly improve the patient’s respiratory status. Here are five things EMS providers need to know about respiratory compromise from COPD:
1. Baseline respiratory status is compromised and declines further during COPD exacerbations.
Lung damage from COPD is irreversible, and people living with COPD have a prescribed treatment plan to manage their symptoms. The plan may include oral and inhaled medications to reduce bronchoconstriction and inflammation, as well as home oxygen to treat chronic hypoxia. In addition to the respiratory compromise caused by COPD, patients with COPD are at higher risk of pneumonia and right-sided heart failure.
Chronic bronchitis causes excess mucus to be secreted in the terminal bronchi, and impairs the cilia lining the terminal bronchi from clearing the secretions. The bronchi are also hypersensitive to inflammation, which increases the frequency of sudden bronchoconstriction. Patient with chronic bronchitis are often overweight, have cyanotic skin and have a frequent productive cough.
Emphysema causes the alveoli to lose elasticity. This reduces the surface area available for oxygen diffusion on inhalation and prevents CO2-filled air from leaving the alveoli on exhalation. Trapped air causes the weakened alveoli to dilate, which eventually destroys the alveolar walls. Once destroyed, several tiny alveolar sacs consolidate into one large sac, or bleb, which further decreases the surface area available for gas exchange. Patients with emphysema are often thin and have a barrel- shaped chest, pink and dry skin, and a dry cough.
EMS is often called for exacerbations of COPD, which occurs when a patient’s baseline symptoms worsen. COPD exacerbations may be triggered by noncompliance with a treatment plan, exposure to an allergen such as cigarette smoke or a respiratory infection. The onset of a COPD exacerbation may be sudden or gradual and patients may try to manage symptoms on their own for a long period before calling 911.
2. Understand how exam findings and point-of-care monitoring tools can be used.
Observe the patient’s level of consciousness and position to assess their work of breathing. Patients in severe respiratory distress may be upright in a tripod position, and patients in respiratory failure may appear drowsy or unconscious. Supraclavicular and intercostal retractions indicate that the patient is using accessory muscles to breathe. Patients with COPD may also exhale through pursed lips, which helps keep weakened alveoli open.
Auscultation of the lungs may reveal high pitched wheezes from air movement through constricted lower airways and low pitched, sonorous wheezes may be heard from air movement across mucus secretions. Diminished or absent breath sounds indicates poor air movement through the lungs, and is an ominous sign.
Attempt to determine how the patient’s current respiratory status compares to their baseline. Patients in severe respiratory distress may only be able speak in short phrases or nod their head yes or no to questions. Ask about what treatment they have used before you arrived, if their respiratory distress today is worse than it has ever has been before, and if they have ever been intubated for respiratory distress. This helps determine initial treatment steps and anticipate the patient’s clinical course.
Measure pulse-oximetry and observe skin color to assess oxygenation. Both may be abnormal at baseline for COPD patients and many COPD patients know what their pulse-oximetry reading normally is. For patients on home oxygen, ask how many liters per minute they normally use, and if they have had to increase it recently.
Compromised exhalation from COPD may cause CO2 retention or hypercarbia. This is a sign that respiratory effort is failing and that they are at risk of respiratory failure from fatigue. Waveform capnography provides continuous feedback on the amount of CO2 exhaled with each breath (end-tidal CO2, or ETCO2), which is normally between 35 and 45 mm Hg. Hypercarbic patients may be in respiratory failure, even if patients are adquetely oxygenated and have normal pulse oximetry.
The shape of the capnography waveform also identifies bronchospasm, which can help differentiate a COPD exacerbation from other causes of respiratory distress, such as heart failure. During bronchospasm, the normally rectangular capnography waveform will have a slurred upstroke, or “shark fin” appearance. The more pronounced the slurring, the more severe the bronchospasm. In emphysema, the plateau of the waveform may slope downward if air remains trapped in the alveoli.
3. Administer oxygen, bronchodilators, corticosteroids and CPAP.
The treatment approach for exacerbations of chronic bronchitis and emphysema is the same. Supplemental oxygen administration is vital for hypoxic COPD patients, but too much oxygen may worsen CO2 retention and be harmful . An Australian study found that COPD patients who received high flow oxygen had a higher mortality rate than patients who received only enough oxygen to maintain SpO2 of 88 to 92 percent. Consider using a nasal cannula or Venturi mask to administer oxygen initially, and use pulse-oximetry as a guide for titration .
Administer nebulized bronchodilators, connected to oxygen at 6-8 LPM, to open lower airways and improve ventilation. Albuterol stimulates beta-2 receptor sites to causes rapid bronchodilation. Ipratropium bromide (Atrovent) inhibits the vagal response, which causes bronchodilation and reduces mucus secretion, and has a twenty minute onset of action. Albuterol and ipratropium bromide can be mixed together in a nebulizer and administered until the patient’s respiratory status improves .
Corticosteroids decrease inflammation from a COPD exacerbation, which also improves air flow through the lungs. Methylprednisolone (Solu-Medrol) can be administered intravenously or intramuscularly, and prednisone can be administered orally. The onset for both medications is four to six hours, so time on scene should not be delayed to administer corticosteroids . While the benefit may not be seed during EMS contact, corticosteroid administration during transport can significantly help the patient’s hospital course.
For patients in moderate to severe shortness of breath, who are alert and have a patent airway, CPAP helps improve oxygenation reduces work of breathing. CPAP works by forcing terminal bronchioles and alveoli open, which increases the surface area available for gas exchange and allows trapped air to escape . CPAP also delivers nebulized medications deeper into the lower airways. Consider applying CPAP early for patients with elevated ETCO2, or had no relief from home breathing treatments before calling EMS.
4. Assist ventilation with caution for patients in respiratory failure.
Respiratory failure occurs when a patient’s respiratory effort can no longer compensate for compromised oxygenation and ventilation. Fatigue, altered mental status and worsening hypercapnea along with decreasing respiratory rate are signs of respiratory failure. Patients in respiratory failure require assisted ventilation with a bag valve mask and possibly placement of an advanced airway.
Positive pressure ventilation may be life saving during a COPD exacerbation, but it has a number of risks and side effects. Patients with COPD are at high risk of barotrauma from excessive ventilation rate and tidal volume. The goal of assisted ventilation is to deliver as little tidal volume as needed to achieve an oxygen saturation of 90 percent. Squeeze the BVM gently over one second and stop squeezing as soon as chest rise is visible. Use waveform capnography as a guide to maintain a ventilation rate of 10-12 breaths per minute and to ensure that the patient has exhaled completely before delivering the next breath.
5. Waveform capnography provides objective data about response to treatment.
Trends in ETCO2 and capnography waveform shape are a reliable indicator of whether the patient is improving or deteriorating. A decrease in respiratory rate, decrease in ETCO2 and shark-fin waveform shift towards a rectangular shape indicates that the patient’s ventilation is improving. However, a rise in ETCO2 with a decrease in respiratory rate indicates that the patient is declining and in respiratory failure. For patients receiving assisted ventilation, a sudden drop in ETCO2 may indicate a pneumothorax or cardiovascular collapse. Use this information to titrate nebulized bronchodilator administration, and to identify patients in need of CPAP or assisted ventilation.
Timely assessment and care can significantly improve the respiratory status of patients with COPD exacerbations. Use information from a physical exam, pulse oximetry and capnography to identify the severity of a COPD exacerbation, to choose the most appropriate treatment options and to assess the patient’s response to treatment.
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