Question

Case Study num11

You are doing a clinical on the medical-surgical floor of a local hospital when Mr. B arrives from the emergency room. Mr. B is a 32-year-old who was thrown off his bicycle in an accident; he has three fractured ribs and a punctured lung. In the ER, they inserted a chest tube to drain air and fluid out of his pleural cavity, allowing his lungs to re-expand. He had one dose of Demerol 3 hours ago for pain and a second dose just before transfer, according to the telephone report from the ER nurse.

1. How does removing air from the chest allow the lungs to expand?  

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Mr. B has been transferred to your floor to wait and see whether the chest tube allows his lungs to completely re-expand. But when he arrives, he is in severe respiratory distress. He says “I felt better before I came into the ER! Is this tube doing anything?”

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You tell the Clinical Nurse Specialist (CNS). As the two of you move him into the bed, you notice that his chest tube bottle is lying on its side on the gurney, with air going into it. When you point this out to the CNS, she immediately grabs the bottle and sets it upright on the floor. You see air start bubbling through the fluid right away. “That was the problem!” she says. “They lost the water seal, and air was going into his chest from the bottle. You would not believe how many times that happens on transport.”

When you examine Mr. B, you have trouble detecting his lung sounds on the left. Even stranger, his apical heart sound is in the wrong place--it is over toward the right side of his chest. His respiration rate and heart rate are both increased, and he is struggling to breathe. “Let's give him a little oxygen. He’ll be a lot better in a half-hour,” says the CNS. “Check back on him.”

2. Why would accumulation of air in his pleural space cause his heart sounds to be in the wrong place?

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While Mr. B is recovering, you check on your other patients. Mrs. H, a 57-year-old first-day post-cholecystectomy patient, is also showing signs of rapid breathing, increased heart rate, and decreased pulse oximeter readings. You ask if she has been using her incentive spirometer to make sure she breathes deeply, and she says, “It hurts my belly incision. There wasn’t anything wrong with my lungs anyway.”

“There will be if you don't use it! You really need to do that at least once an hour. It's to keep your alveoli from collapsing.”

“Why would they collapse? The doctors didn't do anything to them, unless that anesthesia gas was toxic.”

3. Why would a post-surgical patient's lungs collapse if there was nothing wrong with them before surgery?

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4. Explain the role of surfactant in the lungs.

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Answer 1

1. During inhalation, the diaphragm contracts and moves downwards and the muscles between the ribs help the ribs to move upwards and outwards. This increases the volume of the chest cavity as a result of which, the pressure in the chest cavity is lower than that outside. Fresh air rushes in through the nostrils and the lungs get filled by air and expand. During exhalation, the diaphragm moves up, the ribs move inwards and downwards, resulting in reducing the volume of the chest cavity and pushing air out of the lungs.

If the chest cavity gets air in it then the lungs do not get enough space to expand. And when the air is removed from the chest cavity, the lungs get enough space to expand, and also the pressure difference inside and outside the body is such that fresh air is inhaled.

2. A stethoscope helps doctors to hear the sounds of the heart and diagnose any illness. A stethoscope works on the principal of multiple reflection of sound waves. Since sound waves can travel in air, the air in the chest cavity interferes with the normal reflection of sound waves and the doctors hear unusual and confusing heart sounds.

3. Many times, after a surgery, a patient breathing is affected because the exchange of gases in the lungs is affected. This is due to application of general anesthesia during the surgery. If the exchange of gases in the lungs is not adequate, the alveoli might begin to collapse. It is probable that anesthesia may disrupt the binding of pulmonary surfactants to the alveolar membrane and cane also lyse the RBCs. Dmages to the lung surfactants is believed to be an important cause which interferes with gas exchange in the lungs, which can lead to alveolar collapse.

4. Pulmonary surfactants are a mixture of lipids and proteins secreted by the lung epithelial tissue into the alveolar space. It helps to reduce the surface tention at the air or liquid interface in the lungs. Without the lung surfactants, the walls of the alveolar sac would stick into each other after exhalation resulting in the collapse of the alveolar sac. The surfactants also help in exchange of lung gases. Therefore, they are carefully regulated by the body under a range of normal physiological conditions throughout life.