Human Physiology: Week 11 – Problem Set 2

Driving Can Be Dangerous to Your Health: An Interrupted Case Study in Physiology Phil Stephens, Department of Biology Villanova University Case copyright by the National Center for Case Study Teaching in Science. Part I—The Grandparents Arrive Dave pulled the cell phone out of his pocket, cursing himself for not putting it on vibrate. The children, Jason and Laura, were both asleep, and he knew that the rest of the day would not be fun if they were awakened from their naps. “Hi, Dave. We’re just a few minutes away,” said his father. “OK, see you soon.” Dave looked at his wife Jen, who smiled. “Come now, Dave, you know your Mom and Dad. There’s no stopping them once they get going; driving 1200 miles in one day. I guess they’re impatient to see their granddaughter. Mom never got over the fact that her hip replacement was scheduled at the same time that Laura was born.” “I know, Jen. She takes being the only grandmother very seriously.” A car pulled into the driveway and Dave and Jen went out to greet their visitors. They all crept into the house and sat in the kitchen quietly drinking coffee. His mother was breathing heavily, which made Dave recall his childhood and what it had been like to grow up with an asthmatic mother. “Hi Grandpa,” said Jason, as he ran into the kitchen in his pajamas. “Hi, big guy. Wow, you’ve grown. How old are you, now?” Jason smiled as he held up four fingers. He extended both arms so that his grandfather could lift him onto his lap. He stood on his grandfather’s legs and looked over his shoulder for presents. Everything stopped when they heard crying from upstairs. “Let’s wait and see if she goes back to sleep.” They all sat quietly, but the crying got worse. Both women stood up. “I’ll get her, Mom. She is beginning to recognize faces, and I don’t want to start you off on the wrong foot.” “Come on, buddy, let’s go out to the car and see what we brought you from Florida.” Dave watched his father and son walking hand-in-hand out the front door, as his wife and daughter come into the kitchen. His mother’s arms went out and he could see the pleasure in her eyes when she held her granddaughter. Laura was holding a stuffed toy bear in her arms. “My goodness, is that your old bear, Dave?” “Yes. We found it in one of the boxes you gave me, and Laura latched onto it. It’s a bit dusty, but we’ve been afraid to wash it because it may fall apart.” Laura giggled as her grandmother cooed to her while carrying her around the kitchen. “Should you be doing that?” Dave asked his mother. “With your hip and all.” “I’m fine, just a little breathless. Guess I’m a little out of shape for babies.” She gave Laura back to her mother and sat down. Her breathing was labored, and Dave recognized the signs of an oncoming asthma attack. He rushed to the door and shouted to his father to get the nebulizer. Dave could hear his mother’s wheezing as she tried to breathe out. He never understood why it was more difficult for asthmatics to breathe out than breathe in, and why exhaling took so much longer than inhaling. His father calmly placed the liquid medicine into the nebulizer cup, plugged in the machine, and turned on the compressor. He helped his wife hold the mask to her face. Soon, her breathing was regular; deeper than normal, but regular. Jen noticed that Jason was alarmed, and she wondered whether he had forgotten that his grandmother had had some attacks during their last visit. “It’s okay, Jason,” she said. “Grandma sometimes has a problem with her breathing. But you can see that her medicine makes her better quickly.” Jason looked relieved and smiled. Questions 1. What do you think triggered the asthmatic episode in this case? 2. Which of the airways (trachea, bronchi, and bronchioles) do not contain rings of cartilage, and are therefore more likely to collapse? Part II—That Night “I’m glad they went to bed early,” said Dave. “They look really tired.” “Yes,” agreed, Jen. “They really shouldn’t have done the entire trip in one day. Florida to New Jersey in 19 hours; must be a record.” “Poor Muff y,” said Jen as she looked down at the old cat curled up in her lap. ”He’s lost his favorite sleeping spot on the spare bed. He’ll have to camp out in our room while your parents are here.” “He smells like tuna. I caught him in the recycling again, and I think he cut his nose on an aluminum can.” Jen smiled. She had been given Muffy as a kitten, long before she knew her husband. Upstairs, Dave’s parents, tired from the long day, were sleeping. Hours later, Dave’s father woke from a deep sleep. His wife’s breathing was labored, and she was wheezing. “Are you okay, Barb?” He knew that his wife was awake, but he did not wait for an answer. He opened the bedroom door and turned the light on in the bathroom. He set up the nebulizer, carried it into the bedroom, and gave the mask to his wife as he plugged it into the outlet. Her breathing became more regular, but it was fast; she was wheezing and seemed anxious. Even in the dim light, Barb looked pale. “I have this pain in my chest and neck, John, and it’s making its way down my left arm.” He reached for her hand and it felt cold and sticky. He placed his finger on the inside of her wrist and felt her pulse racing. “I think we need to go to the hospital, Barb.” “I know, but the pain gets worse when I move. It was just an ache before you went to the bathroom, but now it really hurts and I feel like I am going to pass out.” Dave knocked on the open bedroom door and entered his parents’ room. His father was dressed and his mother was clearly distressed. “I heard Mom coughing. Is everything okay?” “I’m not sure. This is the worst attack she’s ever had. I think we need to get her to the hospital.” Dave pulled on some clothes and in no time he and his father had his mother in the backseat of the car. The hospital was only a few miles away. Questions 1. What symptoms indicate that this may be something other than just a bad asthmatic attack? 2. With the above symptoms in mind, do you wish to speculate about Barbara’s condition? Part III—The Hospital John pulled up in front of the hospital and opened the back door of his car. He saw Dave holding a bloody tissue as they picked up his wife and carried her into the Emergency Room. The nurse saw the two men holding the older woman and the blood on the tissue, and ushered them into a cubicle. The nurse put a clip on Barbara’s finger and turned on the heart monitor. The two men could hear the fast beeping sounds and saw “95 bpm” appear in the lower right corner next to the heart icon. The nurse started an IV, and took Barbara’s blood pressure (90/58). Finally, she put a plastic ring around Barbara’s head and a tube up each nostril. “What’s that for?” asked John, concerned for his wife. “It’s called a nasal cannula. It’s used to administer oxygen, should the doctor decide that it’s necessary.” The nurse stepped back when the doctor entered the cubicle and she began to examine Barbara. John told her about the asthma attack that afternoon, and the second unusual attack that had happened in the last hour. “Did your wife complain of chest pain?” “Yes, she said that it was in her chest, neck and left arm. I thought that she was having a heart attack.” “That is possible,” continued the doctor. “Are your wife’s legs usually swollen?” John explained that his wife’s legs often swelled when they took road trips because they were in the habit of driving long distances without stopping. The doctor frowned at John. “Did you notice that the swelling is worse in her right leg?” “No doctor,” replied John. “But her right hip was replaced about six months ago.” “Your wife had major surgery, and you drove how far?” “That was my fault,” said Barbara. “My granddaughter was born around the time I had my hip surgery, and I wanted so desperately to see her.” “If my initial prognosis is correct,” the doctor continued, “you may be staying here for a few days.” She reached down and turned on the flow of oxygen through the nasal cannula, and made notes on a chart. “An orderly will take you to your room. I’ll schedule you for some tests.” The bed was pushed out of the cubicle and John went to follow. The doctor turned to John and continued, “Perhaps you should go to Admissions while we get your wife settled in. I am afraid there’s a mountain of paperwork waiting for you.” Questions 1. 2. 3. 4. 5. 6. 7. Is Barbara’s heart rate normal? Is Barbara’s blood pressure normal? What can you conclude from these two observations? Would a heart attack explain the low blood pressure and fast heart rate? How could a heart attack result in labored breathing? Why does a lack of movement create swelling in Barbara’s legs? Why is swelling restricted to her legs? Why didn’t her arms swell? Part IV—Tests, Tests, and More Tests John held his wife’s hand. The hip replacement surgery had worried her, but at least she understood what was going on. Tests using computers and X-rays were something else because she did not understand them. He smiled as he remembered how she would spend hours on the Internet doing research before surgery. “I didn’t know that they could do another X-ray so soon after the ones I had for the surgery, but the technician said that it was necessary to rule out a lot of possibilities. Did you go on the Internet, as I asked you? What did you find out about the V/Q scan I had?” Barbara asked John. “The Internet is a wonderful, thing, Barb. I think I may be your first convert,” said John as a fumbled in his pocket. He put on his glasses and read his notes on the folder paper. “Did they get you to inhale a powder and take pictures, and then take more pictures after they injected something into your vein?” asked John. “Yes. The technician said that they were radioactive tracers, but the radiation was at such low levels that it was not dangerous.” “Well, that sounds right. This ventilation quantification scan, or V/Q scan as you called it, allows them to see air flow and blood flow through your lungs,” said John. “They seemed to get the results quick enough, because then they took me for a spiral CT scan, which apparently takes a bunch of x-rays and then uses a computer to make a 3-dimensional picture of me! It’s really amazing what they can do these days.” “What I don’t understand,” Barbara continued, “is why they scanned my legs with the CT and then did an ultrasound. I know my legs are swollen, perhaps a little worse than usual, but they always swell up after long car trips.” John stood up and walked around the bed. He picked up the chart hanging on the bottom of the bed and glanced at the notes written when his wife was admitted. Test ECG Heart Rate (bpm) Blood Pressure (mmHg) Arterial PO2 Arterial PCO2 Blood pH Blood creatine phosphokinase-2 Blood troponin-I Breathing Rate Breathing Sounds Asthmatic Barbara Normal wave forms 95 90/58 78 46 7.25 2.7 nanogr/mL 1.9 microgr/L 20, labored Wheezing yes Normal Normal About 70 110-120/65-80 100 40 7.4 3 nanogr/mL Less than 3 nanogr/L 12 - Questions 1. 2. 3. 4. 5. 6. What do the ECG and the blood levels of creatine phosphokinase-2 and troponin-I tell you about the likelihood that Barbara had a heart attack? Why are Barbara’s arterial PO2, PCO2, and pH values different from normal? Why did the doctor ask for a CT scan and ultrasound of Barbara’s legs? With Barbara’s symptoms in mind, and the tests that were performed, do you wish to speculate about her condition? Are your ideas consistent with her blood pressure and heart rate? Why was her breathing increased?