Chapter 28
Respiratory Care
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Another cause of impaired oxygenation may be secre- tions in the alveoli or damage to the alveoli caused by chronic lung disease. When the alveoli are not fully func- tional, less oxygen can cross into the blood and less carbon dioxide is able to leave the blood. Low oxygen in the blood may also be caused by a situation in which the patient is unable to fully expand the lungs because of fl uid or pus in the chest cavity or a blood clot in the lung preventing circu- lation to the alveoli. Patients who have had surgery or chest trauma may have hypoxemia caused by pain that prevents them from taking a deep breath. Chronic lung disease is also a cause of hypoxemia. Over time, the alveoli and airways are damaged, making them unable to expand and move air in and out, so oxygen does not cross into the alveolar capillaries to be taken to the body tissues. Damage or trauma to the lung itself also can cause hypox- emia. If a lung collapses, called atelectasis, expansion does not occur, so air is not pulled into the lungs. This may be the result of trauma such as a bullet or knife wound to the chest. It also may be caused by blockage of the airway to the lung, preventing expansion of the lung. For example, if a large tumor is blocking the air path in the right main bronchus, inhaled air is unable to fi ll the lung. Be aware that a patient can have a normal pulse oximetry reading and still suffer from hypoxia. If the blood is carry- ing adequate amounts of oxygen, the pulse oximetry reading will be normal. However, the oxygen may not be crossing the capillary wall and entering the tissue cells. Box 28.2 summa-
Box 28.1 Signs and Symptoms of Hypoxia
When patients become hypoxic, the early symptoms may be missed if you are not aware of them. By the time the later symptoms are evident, the patient is severely hypoxic. It is important to assess your patients for the early subtle signs and the more apparent ones.
Early • Agitation • Anxiety • Changes in level of consciousness • Disorientation
• Headache • Irritability • Restlessness • Tachypnea
Late • Bradycardia • Cardiac arrhythmias • Cyanosis • Decreased respiratory rate (bradypnea) • Retractions
Real-World Connection Effects of Hypoxia on Thinking
rizes the causes of hypoxia and hypoxemia. Caring for Patients With Impaired Oxygenation
Hypoxia to the brain can cause changes in mental function, including affecting judgment. A home health nurse went to visit a patient with chronic lung disease who had recently been hospitalized with respiratory failure. When the nurse arrived, she found that the patient had recently discharged his gun in his home. He had seen his reflection in a mirror, and his hypoxic brain had misinterpreted the face as that of a stranger; he thought that someone was looking in the window of his home. After discharging the gun, he realized that he had shot at his own reflection. His oxygen saturation was very low at 66%, and he was readmitted to the hospital. Causes of Impaired Oxygenation A variety of situations can contribute to impaired oxygen exchange. It may be the result of some type of obstruction in the pharynx, trachea, or bronchi causing a decrease in inspired air. If the nose is blocked because of mucus congestion, the body uses an alternative path and mouth breathing occurs. If the trachea is blocked by secretions, coughing clears them. If the trachea becomes blocked by a foreign body, such as a piece of food, and coughing is either impossible or not suf- fi cient to remove the blockage, the Heimlich maneuver can be performed to clear the airway. If the bronchi or bronchi- oles are blocked by thick mucus or secretions, deep coughs and possibly mucus-thinning agents are required to clear it.
You will care for many patients with impaired oxygenation. Generally, these patients are anxious and frightened; being unable to get your breath is a terrifying experience. As the patient’s nurse, it is very important for you to remain calm.
Box 28.2 Causes of Hypoxia and Hypoxemia
A variety of conditions can lead to hypoxia and hypoxemia. These may be caused by a mechanical problem that interferes with air entering the body, blood conditions interfering with the blood’s ability to transport oxygen, side effects of medications, or environmental situations. Causes include the following: • Airway obstruction caused by a tumor, choking on a foreign body, thick mucus, or swollen airways • Anemia • Atelectasis (collapsed lung) • Chronic lung disease • Decreased cardiac output • High altitude • Hypoventilation caused by anesthetics, sedatives, or coma • Poor peripheral circulation • Pulmonary embolus
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