CASE 2

A very wealthy family from the Boston area has been looking forward to their vacation on Nantucket Island for several months. (Housing on this exclusive resort island is usually reserved years in advance, so they were lucky to find a place on relatively short notice.) The family especially enjoys hiking through the undeveloped parts of the island that have been preserved in their more or less natural state because this provides such a sharp contrast to their everyday experiences in downtown Boston. Occasionally, they manage to spot birds and other forms of wildlife that are now rare in the city. However, being from the big city, they are unaware that the lovely, undeveloped parts of this island also provide a fine environment for ticks and other such creatures, so they fail to use insect repellent or other precautions against bites.

About a week into the vacation, while the family is on one of their beloved pastoral jaunts through the wilderness, their 16-year-old son notices a biting sensation on his leg. Assuming that it's just a mosquito, he ignores it. About two weeks after returning from their vacation, the son begins to experience malaise. Over the next two weeks, he develops a combination of irregular fever, headache, chills, sweating, myalgias, fatigue, and pronounced weakness. These symptoms persist for over two weeks, without any signs of letting up, so the family seeks medical advice. The boy's vital signs are: T = 38.5ºC, R = 18, P = 85, BP = 105/75 mm Hg. The physical examination detects mild hepatomegaly and splenomegaly, but there are no other remarkable findings. The physician asks the family about various recent activities, including travel, meals eaten at restaurants, etc. They mention the vacation on Nantucket Island but point out that it has been several weeks since they returned, so they don't see how that could be related to their son's problem.

Question 2.1: What is your preliminary diagnosis?

Question 2.2: What is the differential?

Question 2.3: What tests should you perform?

Question 2.4: What is the most likely causative agent?

Question 2.5: How does this agent produce the illness?

Question 2.6: How is this disease transmitted?

Question 2.7: How is this disease treated?

CASE 3

A 60-year-old woman with stage IV cervical carcinoma undergoes extensive pelvic surgery (pelvic exenteration) in order to remove the tumor. The surgical procedure involves removal of all pelvic organs, removal of a segment of the ileum to construct a new bladder, and a colostomy. At first, the patient appears to be recovering very nicely. During the evening of the third postoperative day, however, the nurse on the night shift notes that the patient's respiratory rate, which was 16-18 per min, has increased to 26 per min. The patient claims that she doesn't feel overly sick. She is not short of breath or in pain, and her temperature is actually slightly subnormal (36.2ºC). By the next morning, she has slight fever (38.3ºC), but she continues to feel reasonably good. Her surgical wound shows no signs of infection, and her abdomen is no more tender than expected. Later in the day, however, it becomes quite clear that the patient is in serious trouble. She is flushed, anxious, and restless. Her BP has dropped from 135/75 to 105/55, and her temperature is 39.2ºC.

Question 3.1: What is your preliminary diagnosis?

Question 3.2: How should you handle this situation?

Case History - Part II

The patient's condition worsens despite your efforts. The following morning, she is short of breath and there is excess fluid throughout her lungs. Intravenous fluids are cut back, and a vasopressor is now required to maintain her blood pressure. Because of this, she is transferred to the SICU for monitoring. To better assess her hemodynamic status, the superior vena cava (Shiley catheter) and one of the pulmonary arteries (Swan-Ganz catheter) are catheterized (the latter via the jugular vein, right atrium, and right ventricle). The patient turns out to have a cardiac output nearly double the normal for a resting adult of her size. Over the next 24 hrs, the patient continues to do poorly. Her urine output decreases almost to zero, and she requires mechanical ventilation to maintain oxygenation. She becomes increasingly edematous. The blood cultures taken earlier are negative.

Question 3.3: What is going on here?

Question 3.4: What can you do to resolve this case?

Question 3.5: How should this patient be treated now?

Question 3.6: What was the most likely causative agent?

Question 3.7: In cases like this, why does BP fall despite high cardiac output?

Question 3.8: What else could have happened if this case went unresolved?