Chapter 28
Respiratory Care
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Oxygen and carbon dioxide move across the alveolar cell membranes and the cell membranes of the capillaries surrounding the alveoli by the process of diffusion. This process occurs involuntarily, meaning that no con- scious thought is given to it. It is important to understand the mechanics of how breathing occurs so that you can grasp the treatments for respiratory disorders affecting those mechan- ics, such as chest tubes, endotracheal tubes, and mechani- cal ventilation. The diaphragm and the intercostals are the muscles required for breathing to occur. When the diaphragm con- tracts in response to stimulus from the phrenic nerves, it moves downward, which increases the size of the chest cav- ity. Intercostal muscles then contract, moving the ribs up and out, which also enlarges the chest cavity from side to side and from front to back. When the chest cavity size increases, it causes the lungs to expand. The pressure within the lungs then drops below atmospheric pressure, or becomes negative pressure. This causes a sort of vacuum; air is pulled into the lungs until the pressure in the lungs equals the pressure out- side the body. The term used to describe this is inhalation, also known as inspiration. As these muscles relax, again in response to nerve stim- ulus, the size of the chest cavity decreases. The ribs come inward, the diaphragm rises upward, and the lungs are then compressed, forcing the air to go out. This is referred to as exhalation, also known as expiration. Regulation of Respiration Nerves and a chemical control mechanism both contribute to the regulation of respirations. The respiratory center is in the medulla, located in the brainstem. This brain function automatically controls inhalation by sending impulses to the phrenic nerve, which causes contraction of the diaphragm and intercostal muscles. Chemical regulation of respirations is in fl uenced by che- moreceptors located in the carotid and aortic bodies and in the medulla of the brain. When these chemoreceptors detect a decrease in the oxygen level of the blood or a change in blood pH, they send a message to the medulla, which in turn causes an increase in the rate and depth of respirations. When car- bon dioxide increases above normal amounts, it causes the blood to become more acidic. The chemoreceptors respond by sending the message to the medulla, which in turn causes the respiratory rate to increase to “blow off,” or remove, excess carbon dioxide, returning the blood pH to normal lev- els. (See Chapter 29 for more information about acid–base balance and the role of the lungs in maintaining blood pH.) Rising carbon dioxide levels that in turn cause the blood to become more acidic provide the brain’s stimulus to breathe. That is why you cannot hold your breath for long periods— not because your oxygen level is falling, but because you are
SKILLS—cont'd
28.4 Administering a Nebulizer Treatment 28.5 Administering Supplemental Oxygen 28.6 Performing Nasopharyngeal and Oropharyngeal Suctioning 28.7 Performing Endotracheal and Tracheostomy Suctioning 28.8 Performing Tracheostomy Care 28.9 Maintaining Chest Tubes
CRITICAL THINKING CONNECTION Clinical Assignment
It can be alarming to see a patient struggle to breathe or to have to assist a patient who must be suctioned to be able to breathe. As the patient becomes more anxious, it is easy for your anxiety to increase as well. This chapter will help you prepare to care for patients who have respiratory prob- lems, assisting them to improve oxygenation and breathe more easily. NORMAL OXYGENATION The term airway refers to the path that air takes as it enters and exits the lungs. The normal pathway is through the nos- trils into the pharynx, into the trachea, and then to either the right or the left bronchus, which branches into the bron- chioles that terminate into the alveoli. When this pathway is unblocked and air is moving freely, it is referred to as a patent airway. The Mechanics of Breathing When the airway is patent, air is inhaled and follows the pathway to the alveoli, where oxygen is absorbed into the blood and carbon dioxide leaves the blood to be exhaled. You are assigned to care for a hospitalized patient tomor- row in clinical who has a tracheostomy. He was injured in a car accident and was on a ventilator for several weeks. He is breathing on his own now, but he still has the trache- ostomy in place. In addition, he has recently developed pneumonia in his right lung. He has a large amount of secretions and requires suctioning every 2 to 3 hours. The tracheostomy will have to be cleaned on your shift and a new inner cannula put in place. He has humidified oxygen at 4 L/min via a tracheostomy collar. Critical Thinking Questions 1. Why is a tracheostomy done? 2. How does a tracheostomy work? 3. How will you suction it? 4. How will you clean it and replace the inner cannula? 5. What is a tracheostomy collar?
• WORD • BUILDING • inhalation: in – in + hala – breath + tion – action exhalation: ex – out + hala – breath + tion – action
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