Pulmonary Embolism - Pulmonary - Medbullets Step 2/3

Snapshot
A 36-year-old woman presents to the emergency department with worsening shortness of breath and pleuritic chest pain. Her symptoms began earlier in the day while she was waiting for her bus to return home. She recently returned from China to the United States for a business meeting. She denies any sick contacts and has not had these symptoms in the past. Medical history is unremarkable. She takes an oral contraceptive and a daily multivitamin. Her temperature is 98.6°F (37°C), blood pressure is 135/82 mmHg, pulse is 112/min, respirations are 24/min, and oxygen saturation is 89% on room air. A CT angiogram performedmed and demonstrates a filling defect in the pulmonary vasculature. She is immediately started on supplemental oxygen and heparin.
Introduction
Definition mechanical obstruction of the pulmonary vascular secondary to a blood clot typically the blood clot is a thromboembolism from a deep vein thrombosis (DVT) Epidemiology risk factors prolonged immobilization (e.g., long travel) malignancy thrombophilia pregnancy hormonal contraceptives Etiology DVT (most common) from the veins of the proximal thigh (iliac, femoral, or popliteal) septic embolism from right-heart endocarditis fat embolism amniotic fluid embolism Pathophysiology occlusion of the pulmonary vasculature results in hypoxemia and subsequent pulmonary vasoconstriction the increased pulmonary constriction causes an increase in pulmonary vascular resistance, which decreases right ventricular stroke volume leading to increased ventricular oxygen demand right ventricular dilatation decreased left ventricular preload (leading to circulatory failure) poor blood flow to the lung, leading to a ventilation-perfusion mismatch Prognosis significantly high mortality without treatment Wells' criteria used to assess for risk of pulmonary embolism (sum the points) signs and symptoms of DVT +3 pulmonary embolism (PE) is the most likely diagnosis +3 pulse is 100/min +1.5 surgery within the past 4 weeks or immobilization for the past 3 days + 1.5 previously diagnosed PE or DVT + 1.5 hemoptysis +1 malignancy with treatment in the past 6 months < 2 points low risk 1.3% incidence of PE consider using d-dimer 2-6 points moderate risk 16.2% incidence of PE consider high sensitivity d-dimer or CTA > 6 points high risk 37.5% incidence of PE consider CTA
Presentation
Symptoms dysnea (most common) pleuritic chest pain cough hemoptysis syncope in cases of a large PE Physical exam tachypnea tachycardia loud P2 hemodynamic instability in cases of a large PE
Imaging
CT angiography of the chest indication imaging study of choice in the diagnostic evaluation of PE sensitivity of ~90% specificity of ~95% comments chest radiography is typically normal or it may show pleural effusions Hampton hump (wedged-shaped infarct) Westermark sign (avascularity distal to the PE) V/Q scan indication performed if the pre-test probability of PE is high but the patient cannot undergo a CT angiogram (e.g., renal failure, pregnancy, or unavailability) interpretation normal rules out PE high-probability treat with heparin low or intermediate probability if clinical suspicion is high, then get a pulmonary angiography Venous duplex ultrasound of the lower extremities indication to evaluate if there are DVTs
Studies
ECG findings sinus tachycardia atrial fibrillation right ventricular strain S1Q3T3 presence of S wave in lead I and Q wave and inverted T wave in lead III T-wave inversions in V1-V4 Arterial blood gas findings hypoxemia hypocapnia respiratory alkalosis alveolar-arterial gradient may be elevated D-dimer has a high sensitivity but poor specificity for PE and a high negative predictive value used to rule-out PE if there is a low pre-test probability
Differential
Myocardial infarction differentiating factor coronary angiography demonstrating coronary occlusion Costochondritis differentiating factor pain with palpation or movement of the arm
Treatment
Medical Non-vitamin K anticoagulation indication initial therapy in patients with PE in order to prevent further clot formation treatment should not be delayed medication options (best initial step in high risk patient with obvious PE) low-molecular weight heparin do not give in renal failure unfractionated heparin dose by monitoring aPTT preferred in kidney injury/failure warfarin indication typically given around the same time as a non-vitamin K anticoagulant is given dose based on INR (goal is 2-3) thrombolytic therapy indication performed in patients with PE who are hemodynamically unstable Operative embolectomy indication performed in patients with PE who are hemodynamically unstable and thrombolytic therapy is contraindicated or who fail thrombolysis IVC filter indication performed in patients with PE who have a contraindication or failure of anticoagulation
Complications
Cor pulmonale Recurrent pulmonary embolism Atrial fibrillation or flutter

Blood, Plasma, Serum	Reference Range
ALT	8-20 U/L
Amylase, serum	25-125 U/L
AST	8-20 U/L
Bilirubin, serum (adult) Total // Direct	0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca²⁺)	8.4-10.2 mg/dL
Cholesterol, serum	Rec: < 200 mg/dL
Cortisol, serum	0800 h: 5-23 μg/dL //1600 h: 3-15 μg/dL 2000 h: ≤ 50% of 0800 h
Creatine kinase, serum	Male: 25-90 U/L Female: 10-70 U/L
Creatinine, serum	0.6-1.2 mg/dL
Electrolytes, serum
Sodium (Na⁺)	136-145 mEq/L
Chloride (Cl^-)	95-105 mEq/L
Potassium (K⁺)	3.5-5.0 mEq/L
Bicarbonate (HCO₃^-)	22-28 mEq/L
Magnesium (Mg²⁺)	1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)
24-28 wks // 32-36 wks	30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks	40-220 ng/mL // 80-350 ng/mL
Ferritin, serum	Male: 15-200 ng/mL Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma	Male: 4-25 mIU/mL Female: premenopause: 4-30 mIU/mL midcycle peak: 10-90 mIU/mL postmenopause: 40-250
pH	7.35-7.45
PCO₂	33-45 mmHg
PO₂	75-105 mmHg
Glucose, serum	Fasting: 70-110 mg/dL 2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation	Fasting: <5 ng/mL Provocative stimuli: > 7ng/mL
Immunoglobulins, serum
IgA	76-390 mg/dL
IgE	0-380 IU/mL
IgG	650-1500 mg/dL
IgM	40-345 mg/dL
Iron	50-170 μg/dL
Lactate dehydrogenase, serum	45-90 U/L
Luteinizing hormone, serum/plasma	Male: 6-23 mIU/mL Female: follicular phase: 5-30 mIU/mL midcycle: 75-150 mIU/mL postmenopause 30-200 mIU/mL
Osmolality, serum	275-295 mOsmol/kd H₂O
Parathyroid hormone, serume, N-terminal	230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C)	20-70 U/L
Phosphorus (inorganic), serum	3.0-4.5 mg/dL
Prolactin, serum (hPRL)	< 20 ng/mL
Proteins, serum

Hematologic	Reference Range
Bleeding time	2-7 minutes
Erythrocyte count	Male: 4.3-5.9 million/mm³ Female: 3.5-5.5 million mm³
Erythrocyte sedimentation rate (Westergren)	Male: 0-15 mm/h Female: 0-20 mm/h
Hematocrit	Male: 41%-53% Female: 36%-46%
Hemoglobin A1c	≤ 6 %
Hemoglobin, blood	Male: 13.5-17.5 g/dL Female: 12.0-16.0 g/dL
Hemoglobin, plasma	1-4 mg/dL
Leukocyte count and differential
Leukocyte count	4,500-11,000/mm³
Segmented neutrophils	54%-62%
Bands	3%-5%
Eosinophils	1%-3%
Basophils	0%-0.75%
Lymphocytes	25%-33%
Monocytes	3%-7%
Mean corpuscular hemoglobin	25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration	31%-36% Hb/cell
Mean corpuscular volume	80-100 μm³
Partial thromboplastin time (activated)	25-40 seconds
Platelet count	150,000-400,000/mm³
Prothrombin time	11-15 seconds
Reticulocyte count	0.5%-1.5% of red cells
Thrombin time	< 2 seconds deviation from control
Volume
Plasma	Male: 25-43 mL/kg Female: 28-45 mL/kg
Red cell	Male: 20-36 mL/kg Female: 19-31 mL/kg

Cerebrospinal Fluid	Reference Range
Cell count	0-5/mm³
Chloride	118-132 mEq/L
Gamma globulin	3%-12% total proteins
Glucose	40-70 mg/dL
Pressure	70-180 mm H₂O
Proteins, total	< 40 mg/dL

Sweat	Reference Range
Chloride	0-35 mmol/L
Urine
Calcium	100-300 mg/24 h
Chloride	Varies with intake
Creatinine clearance	Male: 97-137 mL/min Female: 88-128 mL/min
Estriol, total (in pregnancy)
30 wks	6-18 mg/24 h
35 wks	9-28 mg/24 h
40 wks	13-42 mg/24 h
17-Hydroxycorticosteroids	Male: 3.0-10.0 mg/24 h Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total	Male: 8-20 mg/24 h Female: 6-15 mg/24 h
Osmolality	50-1400 mOsmol/kg H₂O
Oxalate	8-40 μg/mL
Potassium	Varies with diet
Proteins, total	< 150 mg/24 h
Sodium	Varies with diet
Uric acid	Varies with diet
Body Mass Index (BMI)	Adult: 19-25 kg/m²