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Med 536 Take-Home Assignment 2014
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Med 536 Introduction to Critical Care Medicine
Take-Home Assignment
Instructions
The goal of this take-home assignment is to expose you to a wider range of clinical
problems encountered in the ICU than we will cover in the course lectures and to help
develop skills with some of the basic diagnostic modalities we use in the ICU on a
regular basis, including arterial blood gases, chest x-rays and electrocardiograms.
The assignment is divided into four sections including:
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•
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Cases about patients with various forms of critical illness (4).
Arterial blood gas cases (8)
Chest x-ray cases (4)
EKG cases (4)
Each case is accompanied by relevant questions, which you should answer to the best
of your ability. Short, concise answers will suffice; do not feel that you need to
provide a treatise on each topic.
You may find that some of these cases are straightforward and others are more
challenging. Try not to get frustrated by the difficult cases. They are designed to get you
to think a bit and to learn how to search for information you may not know already or
which may not have been presented to you in your regular didactic sessions. Have fun
with this part of the process.
Many of these cases contain images of physical exam findings, chest x-rays, chest CTs
or electrocardiograms. In case these images do not reproduce well on your computer or
printout, we have also provided a PDF document which contains larger versions of the
images.
Each group is expected to turn in one completed assignment. It is up to each
group to decide on how they would like to divide up the work (There is a very
logical way to do this given the number of cases in each section and the number
of students in each group). Collaboration within the group is encouraged.
Completion of this assignment is required to pass this elective
Due Date: Tuesday March 4
Med 536 Take-Home Assignment 2014
Laboratory Values – Normal Ranges
Chemistry Panel:
Sodium: 135 - 145 mEq/L
Potassium: 3.6 - 4.0 mEq/L
Chloride: 90 - 110 mEq/L
Bicarbonate: 23 - 26 mg/dL
BUN: 5 - 20 mg/dL
Creatinine: < 1.0 mg/dL
Glucose: 80 - 100 mg/dL
Lactate: < 2 mg/dL
Osmolarity: 280-296 mOsm/L
Ammonia: < 60 mg/dL
Complete Blood Count (CBC)∫
White blood cell count (WBC): 4 – 10 x 109/L
Hematocrit (Hct): 35 - 45%
Platelets: 150 – 400 x 109/L
Liver Panel / Abdominal Labs
Aspartate Transaminase (AST): 20 - 40 U/L
Alanine Transaminase (ALT): 20 - 50 U/L
Alkaline Phosphatase: < 100 U/L
Total Bilirubin: 0.2 - 1.5 mg/dL
Amylase: < 100
Lipase: < 150 U/L
Arterial Blood Gas
pH: 7.36 – 7.44
PCO2: 38-42 mmHg
PO2: > 60 mmHg
HCO3: 23-26 mmol/L
Abbreviations and Glossary
BUN: blood urea nitrogen
FIO2: fractional concentration of oxygen
ER: Emergency room
Gravida: the number of times a woman has been pregnant
HCO3: bicarbonate
Para: the number of pregnancies a woman has successfully carried to delivery
PCO2: partial pressure of carbon dioxide
PO2: partial pressure of oxygen
PEEP: Positive end-expiratory pressure
SpO2: oxygen saturation (measured by a pulse oximeter)
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Med 536 Take-Home Assignment 2014
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Cases of Patients With Critical Illness
Case 1
A 55 year-old man was brought into clinic by his wife, who noted two days of
increasing confusion and a new skin rash. His past medical history includes
coronary artery disease, Type II diabetes mellitus and hypertension. 6 months
ago, he underwent coronary angiography with stent placement in the right
coronary artery during a work-up for chest pain on exertion. His medications
include aspirin, metoprolol, clopidogrel, lisinopril, metformin and glipizide. He
had been chest pain free since the time of the procedure and had only
complained of some increasing fatigue in the days leading up to the onset of his
confusion. In clinic, he was febrile to 38.9°C with a blood pressure of 145/89, heart
rate of 105 beats/minute and a respiratory rate of 22. He was confused and
oriented only to self. His physical exam was unremarkable except for the
presence of a rash shown below:
Question: How would you describe this rash? Of what problem is this finding
suggestive?
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Question: In addition to the rash, what are the other noteworthy aspects of his
presentation?
Laboratory studies are obtained and reveal the following: Complete blood count:
WBC 10, Hematocrit 28%, Platelet count 39. Chemistry panel: Sodium 139,
Potassium 4.2, Bicarbonate 21, BUN 35, Creatinine 2.3, Glucose 105. Liver panel:
AST 35, ALT 42, Alkaline Phosphatase 115, Total Bilirubin 1.5.
Question: What abnormalities can you identify in the laboratory results?
Shortly thereafter, the lab calls and tells you the patient has an abnormal
peripheral blood smear. You go down to look at the lab and find the following:
Question: What is the relevant finding in the peripheral blood smear?
Question: What is the differential diagnosis for the patient’s low hematocrit and the
finding on his peripheral blood smear?
Question: What is the differential diagnosis for the patient’s low platelet count?
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Question: Can you think of a diagnosis that ties together the hematologic findings and
his presenting symptoms and signs?
Question: What is the appropriate management?
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Case 2
A 42 year-old gravida 6 para 5 woman presented to the hospital in labor several
hours ago. She is 37 weeks into her pregnancy. At the time of her arrival her
blood pressure was 110/77 (prior to pregnancy, she had blood pressures in the
130s/80s range) and a heart rate of 105 (her pre-pregnancy heart rate in the mid80s). On her admission examination, she has clear lung sounds and a tachycardic
rhythm with a 2/6 systolic ejection murmur heard throughout her precordium and
best at the left sternal border. She has an obviously pregnant abdomen and 2+
bilateral lower extremity edema. She was placed on a fetal monitor and was
having contractions every 5 minutes.
Question: Are there any aspects of her vital signs or physical exam that are concerning
at this time?
The patient was progressing normally through labor, but then developed abrupt
onset of chills and nausea followed by dyspnea and hypoxemia. The obstetrics
service has called down to the ICU for assistance because her oxygen saturation
has fallen to 85% on room air and her blood pressure has fallen to 87/55. Her
heart rate is 115. On exam, she is in obvious respiratory distress with labored
respirations and use of accessory muscles of respiration. She has diffuse
crackles on lung exam. Her murmur is unchanged. On her laboratory studies, her
sodium is 138, potassium 4.0, creatinine 1.0. WBC 9, hematocrit 29%, platelet
count 200.
Question: Which of these laboratory studies, if any, are abnormal in this pregnant
patient?
The patient is put on supplemental oxygen. An arterial blood gas is obtained
while she is on a high-flow facemask with an FIO2 of 0.8. It shows pH 7.52, PCO2
22, PO2 55, HCO3 18 Base Excess -7.2.
Question: How would you interpret the arterial blood gas?
Question: How does this blood gas compare to what you would expect for a healthy
pregnant woman who was also in the late third trimester of her pregnancy?
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A chest x-ray is obtained and is shown below:
Question: How would you describe this chest x-ray?
Question: What is the differential diagnosis for respiratory distress in a pregnant
woman?
Question: Given the chest x-ray findings and other aspects of her clinical presentation,
what do you think are the leading possibilities in this case?
Despite efforts to support her oxygenation with supplemental oxygen by
facemask, she continues to deteriorate and a decision is made to intubate her
and proceed to urgent cesarean section.
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Question: Why is intubation fraught with potential complications in a pregnant woman?
The patient is intubated and started on mechanical ventilation. She is put on
assist control with a tidal volume of 8 ml/kg, respiratory rate of 25 and an FIO 2 of
1.0 and a PEEP of 5 cm H2O. Despite this, her oxygenation remains poor, with an
SpO2 of 87% and a PO2 of 60.
Question: What can you do to improve her oxygenation at this point?
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Case 3
You are working in the emergency room in a hospital on the Navajo Reservation
in Arizona when the medics bring in a man who was found at home with altered
mental status. He is well known in this emergency room for frequent visits due to
alcohol intoxication or withdrawal. On arrival, he is afebrile with a heart rate of
108 and a blood pressure of 90/48. He has emesis on his shirt and pants. He is
unresponsive to verbal commands but does withdraw to deep painful stimuli. He
has a cough and a gag. His lung sounds are clear and his cardiac exam is
noteworthy only for the tachycardic rhythm and the absence of a murmur. He has
no abdominal pain, no lower extremity edema and no rashes. There are no
stigmata of chronic liver disease.
Your initial set of laboratory studies comes back. His chemistry panel shows
sodium 138, chloride 95, bicarbonate 11, glucose 126, BUN 30, creatinine 1.4. His
complete blood count shows WBC 12, hematocrit 42, platelets 90. A room air
arterial blood gas is done and reveals: pH 7.15, PCO2 25, PO2 115, HCO3 11. Base
Excess -15.5.
Question: How would you interpret the arterial blood gas?
Question: What is his serum anion gap?
Question: What is the differential diagnosis for his primary acid-base abnormality?
Additional laboratory studies come back and reveal the following:
Acetaminophen level < 10, Aspirin level < 10, urine toxicology screen is negative,
blood alcohol level 0, serum osmolarity 330. His chest x-ray shows no focal
opacities?
Question: What is the significance of the serum osmolarity in this case? How does that
affect your differential diagnosis?
Question: What further diagnostic tests would you order?
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The laboratory calls to inform you that the microscopic analysis of the patient’s
urine sample was abnormal. A slide of the urine sample is shown below:
Question: What is the main finding in this slide? How does that affect your differential
diagnosis?
Question: What treatment would you initiate at this time?
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Case 4
A 70 year-old woman with a history of tobacco use and hypertension presents to
the emergency room with substernal chest pain radiating to her neck and arm
that has been present for the past two hours. She has nausea and diaphoresis as
well. Upon arrival, she is afebrile with a blood pressure of 145/89, heart rate of 102
and a respiratory rate of 24. Her oxygen saturation is 98% on room air. On
physical exam, she is anxious appearing and diaphoretic. Her neck veins are not
elevated. She has scattered crackles at her lung bases, a rapid heart rate with a
normal rhythm and a 2/6 systolic ejection murmur heard best at the left lower
sternal border that does not radiate to the neck or the axillae. The remainder of
her exam is unremarkable.
Question: What are your initial management priorities for this patient?
An electrocardiogram is performed and is shown below:
Question: What is your interpretation of the electrocardiogram?
Question: What is the most appropriate intervention for this patient at this time?
The patient undergoes appropriate intervention for her diagnosed problem. She
spends two days in the cardiac intensive care unit afterwards and is then
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transferred to the floor. On the fourth day of her admission, you are called to the
bedside to evaluate her for hypotension. Upon arrival in the room, you find her
with a blood pressure of 80/46 with a heart rate of 105. When you examine her,
you find that she is diaphoretic and her color looks poor. Her neck veins are
elevated to the angle of her jaw. She has no crackles on lung exam. Her trachea is
on the midline. On cardiac exam, she has a rapid rhythm but you have difficulty
hearing the heart tones. Her abdominal exam is unremarkable and she has trace,
symmetric lower extremity edema.
Question: What is the differential diagnosis for her hypotension?
An electrocardiogram is obtained and is shown below.
Question: How would you interpret the electrocardiogram (Hint: think about some
noteworthy differences compared to the original EKG)?
Question: What is the next most appropriate diagnostic step for this patient?
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Arterial Blood Gas Cases
In the space that follows you will find a series of cases that include arterial blood gases.
For each case, you should describe the acid-base status of the patient (eg. acute,
metabolic acidosis with respiratory compensation) and determine whether the patient
has an alveolar-arterial oxygen difference. Finally, you should provide a short one-two
sentence explanation for the observed abnormalities.
ABG Case 1
A 55 year-old man is brought to the surgical ward following an elective orthopedic spine
surgery. He is on maintenance intravenous fluids as well as a patient-controlled
analgesia (PCA) with hydromorphone (a narcotic) running at 0.2 mg/hr with additional
boluses on demand every 8 minutes as needed. He was fine upon arrival and the nurse
gave him an extra dose of pain medications because she felt he was in a lot of pain. 20
minutes later, she comes back to check on him and finds him unresponsive. A rapid
response is called and upon arrival of the team, an arterial blood gas is drawn with the
patient breathing air. It shows: pH 7.15, PCO2 65 , PO2 60, HCO3 28. A chemistry panel
is drawn and comes back with Sodium 140, Chloride 105, Bicarbonate 27, and
Potassium 4.2.
Acid-base status:
Alveolar-arterial oxygen difference:
Explanation for the clinical picture:
ABG Case 2
A 22 year-old woman presents to the emergency room at 2200 complaining of severe
nausea and vomiting. Her symptoms came on suddenly late in the afternoon after she
had eaten lunch with some friends at the taco truck on 45th street in Wallingford. In the
emergency room, she has labs drawn which show a sodium of 132, chloride 90,
bicarbonate 30, creatinine 1.3 and potassium 3.6. An arterial blood gas was drawn with
the patient breathing air and reveals: pH 7.47 PCO2 49, PO2 80, HCO3 34.
Acid-base status:
Alveolar-arterial oxygen difference:
Explanation for the clinical picture:
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ABG Case 3
A 12 year-old boy is brought into the emergency room at Children’s Hospital by his
parents for evaluation of abdominal pain and nausea. He has been feeling poor for
several days and has not been eating well. His pain is primarily in the right lower
quadrant and is worse with movement. On exam, his abdomen is diffusely tender
without peritoneal signs. Laboratory studies are drawn and reveal: Sodium 132,
Potassium 4.4, Chloride 90, Bicarbonate 14, Creatinine 1.2, Glucose 452. An arterial
blood gas is drawn with the patient breathing air and reveals: pH 7.30 PCO2 27, PO2
110, HCO3- 13.
Acid-base status:
Alveolar-arterial oxygen difference:
Explanation for the clinical picture:
ABG Case 4
A morbidly obese man with a history of sleep apnea goes to see his primary care
provider because of increasing knee pain. His provider initiates a work-up and sends
him home with a prescription of oxycodone 5 mg tablets to be used on an as-needed
(prn) basis. The next morning, his wife has difficulty arousing him from sleep and calls
911. He is brought into the emergency room by medics where he arouses to voice but
quickly falls back to sleep. Laboratory studies are drawn and reveal: Sodium 134,
Potassium 3.9, Chloride 99, Bicarbonate 31, Creatinine 1.1, Glucose 210. His arterial
blood gas done while he is breathing air shows pH 7.22, PCO2 82, PO2 38, HCO3- 32.
Acid-base status:
Alveolar-arterial oxygen difference:
Explanation for the clinical picture:
ABG Case 5
A 57 year-old man was admitted for an upper gastrointestinal bleed and undergoes
upper endoscopy during which time they found he had a gastric ulcer. After the
procedure, he complains of a sore throat and the senior resident writes and order for
him to get some cetacaine spray that he can use on as as-needed basis. Later that
evening, he is noted to have a drop in his oxygen saturation to 88% while breathing air.
He is put on a nasal cannula but his saturation does not improve. Eventually, he is put
on an non-rebreather mask but his saturation remains at 87%. A chest x-ray is obtained
and shows no opacities. An arterial blood gas is drawn while he is on the nonrebreather mask and demonstrates: pH 7.49, PCO2 32, PO2 357, HCO3- 22.
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Acid-base status:
Alveolar-arterial oxygen difference:
Explanation for the clinical picture:
ABG Case 6
A 23 year-old woman with a history of borderline personality disorder is brought into the
emergency room by her roommate with altered mental status and vomiting. The
roommate states that she recently had a fight with her boyfriend but she did not know
any other details. On exam, she is arouseable but needs frequent stimulation to remain
awake and appears to be breathing quite heavily. Her lung sounds are otherwise
normal, as is her chest x-ray. You obtain labs. The ABG done while she is breathing air
shows: pH 7.52, PCO2 22, PO2 112, HCO3- 17. The chemistry panel shows: Na+136,
Cl- 102, HCO3- 16.
Acid-base status:
Alveolar-arterial oxygen difference:
Explanation for the clinical picture (hint: think about the serum anion gap):
ABG Case 7
You are working in the ER at Harborview Medical Center in December. The medics
bring in a 45 year-old man they found on the ground in Pioneer Square. His body
temperature in the ER is 30 degrees C. An arterial blood gas is drawn while he is
breathing air and shows pH 7.31, PCO2 48, PO2 88, HCO3 23. Chemistry panel: Na+
128, Cl- 98, HCO3- 23.
Acid-base status:
Alveolar-arterial oxygen difference:
How does his body temperature affect the interpretation of this blood gas:
Explanation for the clinical picture:
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ABG Case 8
A 68 year-old man with a history of very severe COPD (FEV1 ~ 1.0L, < 25% predicted)
and chronic carbon dioxide retention (Baseline PCO2 58) presents to the emergency
room complaining of worsening dyspnea and an increase in the frequency and
purulence of his sputum production over the past 2 days. His oxygen saturation is 78%
while he is breathing air. Before he is place on supplemental oxygen, an arterial blood
gas is drawn while he is breathing air and reveals: pH 7.26, PCO2 68, PO2 48, HCO330.
Acid-base status:
Alveolar-arterial oxygen difference:
Explanation for the clinical picture:
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Chest X-ray Cases
Chest X-ray Case 1
A 45 year-old man is admitted with pneumonia and develops ARDS. He was on
mechanical ventilation and was requiring an FIO2 of 0.9 and PEEP of 20 cm H2O to
maintain his SpO2 in the low to mid-90% range. All of a sudden, he has a drop in his
oxygen saturation to the mid-80% range. You check the ventilator and notice that his
compliance has decreased. You obtain a chest x-ray that is shown below.
What finding in the chest x-ray explains the change in the patient’s condition?
How would you treat this problem?
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Chest X-ray Case 2
A 50 year-old woman has been on the ventilator for treatment of pneumonia and ARDS.
She has been producing a significant amount of thick secretions. The nurses noted that
she was more agitated than normal and that her oxygen saturation, which had been
97% on an FIO2 of 0.6 and a PEEP of 10 cm H2O, had now fallen to 80%. You obtain a
chest x-ray, which is shown below.
What two problems can cause a unilateral lung whiteout on chest x-ray and how can
you distinguish between them on chest x-ray?
What do you think is the cause of the unilateral whiteout in this case?
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Chest X-ray Case 3
A 55 year-old man presents with two days of fever, productive cough and increasing
dyspnea.
Would you classify this opacity as “alveolar” or “interstitial”?
Where is the opacity located (i.e. which lobe)?
The patient decompensated and required intubation. The lung fields looked roughly the
same on the repeat film. His oxygen saturation post-intubation is 85% on an FIO2 of 0.5
and PEEP of 5. Which is the most appropriate first move to improve his oxygenation:
increase the PEEP or increase the FIO2?
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Chest X-ray Case 4
A 55 year-old man with a history of poorly controlled blood pressure presents with the
sudden onset of stabbing chest pain that radiates to his back behind his scapulae. His
vitals upon arrival in the ER include a blood pressure of 210/115, heart rate of 105 and
a respiratory rate of 24. His oxygen saturation is 96% on room air.
What is the primary finding?
What is the next most appropriate test to order to confirm the diagnosis?
What are your initial management priorities?
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EKG Cases
In the space that follows you will find five cases of patients with abnormal
electrocardiograms. Each case contains a short synopsis of the patient’s presentation.
Read the electrocardiogram as you would for any patient, using a system to work
through all of the key steps and see if you can identify the main finding (there is only
one abnormality per EKG).
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EKG Case 1
A 47 year-old woman with chronic kidney disease due to poorly controlled hypertension
and diabetes presents to clinic stating that she is feeling poor with nausea and
lightheadedness. She missed her dialysis appointment yesterday her car broke down.
What is the primary finding?
How will the EKG evolve if you do not treat this problem promptly?
How would you manage the problem?
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EKG Case 2
A 55 year-old woman presents to the emergency room complaining of palpitations.
These began 4 hours ago. She has never had a similar problem in the past.
What is the primary finding in the EKG?
What can you do to treat to slow the rate down?
What can you do to treat the underlying rhythm?
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EKG Case 3
A 62 year-old man was admitted to the hospital with a myocardial infarction. Two days
later while recovering in the coronary intensive care unit, he is noted to have altered
mental status. At the same, time, his heart rate is reading 25 beats per minute on his
monitor. His blood pressure is 75/43. An EKG is obtained and shows the following:
What is the underlying rhythm?
What can you do to improve his blood pressure?
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EKG Case 4
A 22 year-old Coast Guardsman presents to the ER with two days of severe chest pain
and worsening dyspnea. The pain is felt of the left, anterior chest and does not radiate
to his neck or arms. It is worse when he coughs or takes a deep breath. Of note, two
weeks ago, he received a small pox vaccination for this Coast Guard. The arm wound
from the vaccination has been healing well.
What is the primary finding in the EKG?
What further work-up is indicated at this time?
What treatment is indicated at this time?