Week 4 - Respiratory Distress

Week 4 – Respiratory Distress

Respiratory distress is a common finding in many patients who call for EMS. There can be many causes including dyspnea, hypoxia, hypercapnia and cyanosis. Despite any fancy tests that can be performed on a patient, the evaluation of respiratory distress depends on careful history and physical examination of the patient. Discussed below are three commons causes of respiratory distress, along with the potential causes of each.

Dyspnea
Dyspnea is the subjective finding of difficult, labored or uncomfortable breathing. There is no single mechanism that causes dyspnea, however most patients will have a cardiac or pulmonary cause.

Common causes include obstructive airway, asthma, COPD, CHF, Unstable Angina/MI and Pneumonia. The most immediately life threatening causes include upper airway obstruction, tension pneumothorax, pulmonary embolism, neuromuscular weakness, and Gullian-Barre syndrome.

Hypoxemia
Hypoxemia is the inadequate delivery of oxygen to the tissues. Oxygen delivery is mainly a function of cardiac output, hemoglobin concentrations and oxygen saturation. Hypoxemia typically results from a combination of five distinct mechanisms:

Hypoventilation hypoxia in which lack of ventilation increases PaCO2, thereby displacing it from the alveolus and lowering the amount delivered to the alveolar capillaries;
Right-to-left shunt in which blood bypasses the lungs, thereby increasing the amount of unoxegenated blood entering the systemic circulation;
Ventilation/perfusion mismatch in which areas of the lung are perfused but not ventilated;
Diffusion impairment in which alveolar-blood barrier abnormality causes impairment of oxygenation;
Low inspired oxygen, typically occurring at high altitudes.

Hypercapnia
Hypercapnia is defined as a PaCO2 above 45 and is exclusively due to alveolar hypoventilation. Factors that affect alveolar ventilation include respiratory rate, tidal volume and dead space volume.

Signs and symptoms can depend on the rate of change and the absolute value of PaCO2. Acute elevations result in increased intracranial pressure, which causes patients to complain of a headache, confusion and lethargy. In severe cases in which the PaCO2 acutely rises above 80, coma, encephalopathy and seizures may be present.


Practical Exercise
1. Your patient is a 35 year old female, who called EMS stating that she was having some difficulty catching her breath. Vital signs are within normal limits, and your assessment reveals that patient is complaining of some nausea and a headache. She is also sluggish to answer your questions.

2. What do you suspect this patient could be suffering from and why?
While performing your assessment, what are some ways you could distinguish between Hypoxemia and Hypercapnia?

3. What would your treatment plan include for the above referenced patient?