An ALS ambulance responds to a report of shortness of breath. Upon arrival, the EMS crew finds a female in her mid-40s complaining of difficulty breathing. She is sitting on a chair in the tripod position and says she has never felt like this before.
Physical assessment reveals that the patient is conscious and oriented with pale, sweaty skin. Her heart rate is 142, sinus tachycardia, with a respiratory rate of 40 and blood pressure of 146/62. Breath sounds reveal expiratory wheezes in all fields. She is able to speak in complete sentences, says she has had a nonproductive cough for three days, and she smokes one pack of cigarettes a day. She denies any other complaints. The remainder of her assessment is unremarkable.
The EMS providers initiate treatment. Supplemental oxygen is administered and an intravenous line is established. An albuterol breathing treatment is administered via nebulizer and the patient indicates that it is helping. During transport to the hospital, the patient’s color improves, her respiratory effort decreases, and she has less wheezing. Vital signs are repeated as the crew arrives at the hospital.
As illustrated above, EMS frequently responds to requests for assistance due to difficulty breathing. This article provides an overview of respiratory and cardiac anatomy, as well as examples of conditions that can result in shortness of breath.
Breathing involves the movement of air through the mouth, nose, trachea and lungs. The trachea divides into the left and right main bronchi, which lead to the bronchioles and alveoli. Gas exchange occurs in the alveoli along the alveolar-capillary membranes. Waste products, such as carbon dioxide, are transported to the lungs by venous circulation to the alveoli, where they are removed when an individual exhales.1-3
The process of breathing involves the interaction of several systems, including the diaphragm, intercostal muscles and brain stem. The diaphragm is a layer of muscle that extends along the bottom of the thoracic cavity, separating it from the abdominopelvic cavity. When relaxed, it has a dome shape. When contracted, it flattens and increases the size of the chest cavity by making it longer. This results in negative pressure within the thoracic cavity and contributes to inhalation. The air within the thoracic cavity is passively released when the diaphragm relaxes.1-3
When the intercostal muscles of the rib cage contract, they pull the rib cage upward, expanding the chest wall and stretching the lung. Negative pressure is created in the thoracic cavity, resulting in inhalation as air is drawn through the respiratory tract.1-3
Breathing is also influenced by the brain stem, which has a respiratory center that is sensitive to the presence of gases in the blood. For example, when sufficient amounts of carbon dioxide (CO2) are in the bloodstream, the brain stem responds by triggering a breath. This helps to remove the CO2.1-3