Chief Complaint: “I can’t breath”
HPI: Pt is a 35 year old female with a past medical history significant for hyperlipidemia and asthma who presents to the emergency department with chief complaint of acute onset dyspnea. The pt states that she is a business executive who travels between Chicago and Tokyo every week. For the last 2 weeks she has been battling a productive cough, runny nose, with night sweats but had no fever. She had been taking over the counter cold medication to deal with these symptoms and they had provided her some relief. She had also been short of breath and had used her albuterol inhaler which had provided symptomatic relief. However, today she returned from Tokyo on a 14 hour flight. She didn’t get up the entire flight because of her cold but did notice some swelling in her left leg during the flight. While collecting her baggage she developed sudden onset 8/10 chest pain worse with deep inspiration, coughing up blood, dyspnea, and tachypnea. She attempted to use her albuterol inhaler but this provided no relief. An ambulance was called and brought to the ED. She required 3L of O2 in transport and could not lie flat. The pt denies any radiating chest pain, nausea, vomiting, or diarrhea.
Review of Systems: (Italics indicates positive)
General: Fevers, Chills, Night sweats, no weight loss
HEENT: No headaches, tinnitus, vision changes, dysphagia
Respiratory: Dyspnea, Cough, hemoptysis
Cardiac: Chest pain, Racing heart, Orthopnea, Leg swelling
GI: No nausea, vomiting, diarrhea, constipation, blood in stool
GU: No changes in urinary frequency, urgency, hesitancy, burning,
Neuro: no weakness, tingling, burning sensation
Past Medical Hx:
Hyperlipidemia
Asthma
Deep Vein Thrombosis-(2010)
Past Surgical History
No pertinent history
Medications
Atorvastatin-20mg daily
Albuterol-PRN
Oral Contraceptive Pills-once daily
Physical Exam:
Vitals: BP 145/ 90 P 115 R 25 Temp 100.0 O2 sat 96% on 3L O2
Wt: 55 Kg Ht:165cm BMI: 20
Appearance: Appears her stated age, in moderate respiratory and painful distress
HEENT: EOMI, conjunctiva are pink with no evidence of jaundice, hearing grossly intact, missing left lateral incisor
Pulm: vesicular breath sounds on the right, diffuse wheezing in the lower lung fields on the left
Cardio: No JVD. No tenderness to palpation. No chest wall deformities. Tachycardic, normal rhythm, normal S1 and S2 no murmurs, rubs or gallops.
Abdomen: bowel sounds heard but hypoactive after 2 mins in each quadrant. Abdomen is soft, not distended, not tender to touch. No guarding or rebound tenderness.
Extremities: Peripheral pulses intact and symmetric bilaterally. Swelling and calf tenderness to palpation 4cm on the right leg, left leg not swollen or tender
Neurologic: Pt is awake, alert and oriented x 3, no focal deficits noted.
MSK: Pt 5/5 muscle strength in all 4 extremities and 5/5 grip strength.
Labs:
WBC 12.1x10^3/uL, RBC 5.19x10^6/uL, Hgb 13.5 g/dl, HCT 43%, MCV 82.9
Na: 137 mEq/mL, Cl 94 mEq/mL, HCO3- 22mmol/L, BUN 8.6 mg/dL, Cr .9 mg/dL, Glucose: 126 mg/dL Tbil .6, AST 19, ALT 15, AlkPhos 67, Total Protein 7.6, Albumin 4.4
D-Dimer: 2000 ng/mL
Troponin I: <0.01 ng/mL
Procalcitonin: <0.05mcg/L
Chest X-ray: Radiologists impression “Normal chest x-ray, no acute findings”
EKG: Cardiologists interpretation “Sinus tachycardia otherwise normal ECG”
Differential Diagnosis
1. Given the pt’s history and physical exam list your differential diagnosis including at least 5 possible diagnoses. (Remember the differential diagnosis should be broad and really just include causes that could account for the relevant symptoms) Essentially what could account for acute onset dyspnea, chest pain, and tachypnea.
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2. Now given the clinical presentation, physical exam and labs What is your top diagnosis? (Use your differential and think through what data lead you to believe your top diagnosis is correct and go against the others)
Possible diagnoses within the differential diagnosis could include mediastinitis, which is an infection of the mediastinum, pulmonary embolism, which occurs when a thrombus travels through the venous system and causes a block in the pulmonary artery, pneumonia, acute respiratory distress syndrome, myocardial infarction, in which acute dyspnea is actually an important diagnostic factor, and hyperventilation syndrome.
In order to further narrow the diagnosis, it is necessary to delve more thoroughly through the lab results, physical exam indications, and clinical presentation:
Troponin I levels below < 0.01 ng/ml contraindicate for the diagnosis of myocardial infarction. Furthermore, there is no visible ST-elevation on the ECG, as would be expected in a patient presenting with MI.
To rule out the possiblity of fluid in the lungs, that could indicate ARDS, we could listen for abnormal, "crackling" breath sounds upon auscultation or look at a chest X-ray.
A chest X-ray or CT scan could also rule out the existence of an infection in the lung which would support a dianosis of pneumonia.
Mediastinitis, in which their is inflammation of the area between the lungs, would usually occur because of an infection, either acute because of suddent trauma, or a chronic illness. Clinically, our patient does not present with these indications, and further chest x-rays would indicate for this diagnosis but is found to be normal.
Hyperventilation syndrome (or HVS) is a condition in which normal metabolic demands are exceeding by the airflow (the minute ventilation), leading to complicated chemical and hemodynamic changes that can cause dyspnea and a general panic state. However, in our patient, Hgb levels appear normal, suggesting that this is not the problem.
The fact that the patient has a history of deep vein thrombosis lends itself to the diagnosis of pulmonary embolism, and suggests that we specifically consider either PE or pulmonar-y hypertension. Pulmonary embolisms can cause a reflex increase in ventilation, which explains the patients tachypnea. This is also consistent with a diagnosis of pulmonary embolism. Further the large high levels of D-dimer, a fibrin degradation product of the coagulation cascade, is indicative of formation of a blood clot. Other lab results indicate elevated WBC counts, (WBC: 12.1x10^3/uL), which are common in patients with PE (in fact, WBC levels often exceed 20,000). Both chest x- ray and ECG readings are normal, which helps elimate other potential diagnoses like myocardial infarction and pericarditis/mediastinitis. The reported sinus tachycardia on an otherwise normal ECG is also consistent with PE.
Futher Tests and Examinations
3. Given your top diagnosis what specific tests do you need to run in order to confirm it?
A CT angiography and CT venography, which would provide information about lung pathology, and allow you to differentiate blood clots from other obstructions in the veins, would be instrumental in further narrowing the diagnosis. Pulmonary angiography has been considered the most effective ("gold-standard") method to diagnose PE, but it is invasive and can often be toxic and intolerable.
Thus, noninvasive procedures, like a V/Q scan, which could differentiate areas in the lung that are less perfused or less ventilated, or an MRI, would also be an effective test to confirm the diagnosis of PE.
4. Results of a VQ Scan are shown below. Before interpreting the results below please elaborate on the following: a.What is the ventilation perfusion ratio (V/Q ratio)? (Include a short discussion on hypoxic vasoconstriction) b.What is a V/Q defect? Does a regional V/Q mismatch normally exist in the lungs? What does it tell you? What do you expect for this situation? (Include short discussion of west zones) c.What is a V/Q scan? How is it performed? d.How would O2 help this patient and how would it change the V/Q ratio? e.What is the interpretation of the scan below (Fig 1)? Match this up with the clinical findings.
The ventilation perfusion ratio is a ratio between the amount of air that is reaching the alveoli, and the perfusion or blood that reaches the alveoli. The crucial point about their relationship is that, while both change with the level of the lung, they do so at different rates. Blood flow changes with a steeper slope, so that at the bottom of the lung, where there is normally a low V/Q ratio, there is more blood flow than ventilation, thus causing under ventilation. At the top of the lung, there exists ahigh V/Q ratio, that means that there is more ventilation than perfusion, and so the area is considered over ventilated. The ratio is approximately 1 (so both the perfusion and ventilation are about equal) around the 3rd rib level.
This mismatch in V/Q ratios occurs in part because of the increasing transmural pressure gradient from the top of the lung to the bottom due to gravity. As one moves down the lung, the transcapillary pressure increases against alveolar pressure, and so at the top of the lung, in west zone 1, alveolar pressure is greater than arterial pressure, which is greater than venous pressure, and there is little perfusion since the vessels are often collapsed. At the bottom of the lung, however, in west zone 3, arterial pressure is greater than venous pressure, which is greater than alveolar pressure; so blood flow is always good here.
A defect in the V/Q ratio occurs when this happens in an unusual way, that goes against the usual setup according to the west zones. A V/Q defect, specifically across the entire lung, indicates a problem with either perfusion or ventilation. In the case of a pulmonary embolism, it is expected that V/Q is elevated in regions affected by the embolism, whereas unaffected areas would have a decreased V/Q.
A V/Q scan uses radioactive material (radiopharmaceutical) to examine airflow (ventilation) and blood flow (perfusion) in the lungs. The aim of the scan is to look for evidence of any blood clot in the lungs, called pulmonary embolism (PE). It examines the movement of gas to assess perfusion (by injection into a vein), and to assess ventilation (by inhalation).
Supplemental O2 may help this patient by increasing the amount of oxygen that can reach the rest of the body. Through a physiological process called anatomical shunting, blood is often shunted from an affected area to the unaffected areas of the lung through hypoxic vasoconstriction. This occurs when those vessels are returning without enough oxygenated blood (reduced gas exchange). Thus the addition of supplemental O2 could increase the PAO2.
The scan below suggests a PE in the left pulmonary artery. There may be an indication of blood being shunted to the right lung, resulting in increased perfusion and a higher difference between the two. The decreased perfusion seen in this scan corresponds with the diffuse wheezing on the bottom of the left lung.
Next Steps and Treatment
5. Given the positive diagnosis and confirmation of your suspicions what additional tests might be indicated in this patient. Why is that important (Hint: Where did the embolus come from? There was a clinical finding and a major criteria of well’s score that would indicate further testing)
The most effective next step is assessing the location of the thrombosis, which is still a potential risk factor for the patient. This can be done using a CT venography that could tell us if the patient still has this thrombosis.
6. What do we do now that we have the diagnosis? What is the mainstay treatment for a PE? Does this actually remove the clot? There are newer treatment modalities available what is the evidence for these? (Hint: Einstein PE trial)
The patient could be put on heparin, which is an anticoagulant that will work right away, even while other tests are being run. Warfarin, which is an anticoagulant and a vitamin K antagonist, will also be given to the patient, but will take longer to become effective. This is more of a preventative treatment to reduce the risk of further clots, especially because of her history of DVT. The patient may be sent home on the warfarin. Thrombolytics, that break up the thrombus, would be productive in breaking up the clot, but would most likely be used in the setting of a myocardial infarction.
A newer drug, rivaroxaban, is also being used in the treatment both PE and DVT. It is an oralinhibitor of clotting factor Xa, and works similarly to other direct thrombin inhibitors (in the same class as apixaban), but requires much less monitering than other anticoagulants like warfarin, which need blood draws to determine the appropriate level of blood thinning. Dosage need only be adjusted to moniter renal function.
References
Alldredge BK, Corelli RL et al. Applied Therapeutics - The Clinical Use of Drugs. Lippincott 10th Edition 359-360.
Büller HR, et al. "Oral rivaroxaban for the treatment of symptomatic pulmonary embolism". The New England Journal of Medicine. 2012. 366(14):1287-1297.
Cham MD et al. Thromboembolic disease detection at indirect CT venography versus CT pulmonary angiography. Radiology 2005 Feb;234(2):591-4.
https://www.nlm.nih.gov/medlineplus/ency/article/003643.htm
Venetz C et al. White blood cell count and mortality in patients with acute pulmonary embolism. Am J Hematol. 2013 Aug;88(8):677-81. doi: 10.1002/ajh.23484. Epub 2013 Jun 20.
Ouellette DR et al. Pulmonary Embolism Workup. Medscape.
https://www.nlm.nih.gov/medlineplus/ency/article/000103.htm
https://www.nlm.nih.gov/medlineplus/ency/article/000081.htm
Kern B et al. Hyperventilation Syndrome. Medscape.
http://emedicine.medscape.com/article/2073935-overview