Pulmonary Embolism- Diagnosis by Dr.Tinku Joseph

PULMONARY EMBOLISMDIAGNOSIS

Dr.Tinku JosephDM Resident

Dept. Of Pulmonary MedicineAIMS, Kochi.

Diagnostic Tests Imaging Studies– CXR– V/Q Scans– Spiral Chest CT– Pulmonary Angiography– Echocardiograpy

Laboratory Analysis– CBC, ESR, – D-Dimer– ABG’s

Ancillary Testing– ECG– Pulse Oximetry

D-dimer Test

Fibrin split product

Circulating half-life of 4-6 hours

Quantitative test have 80-85% sensitivity, and 93-100% negative predictive value

• False Positives:

Pregnant Patients Post-partum < 1 weekMalignancy Surgery within 1 weekAdvanced age > 80 years SepsisHemmorrhage CVA

Collagen Vascular DiseasesHepatic Impairment

Arch Intern Med 2004;140:589

Diagnostic Testing

• D-dimer

– Qualitative• Bed side RBC agglutination test

– “SimpliRED D-dimer”

– Quantitative• Enzyme linked immunosorbent asssay

“Dimertest”• Positive assay is > 500ng/ml • VIDAS D-dimer, 2nd generation ELISA

test

D-DIMER• False Positive D-Dimer– Pregnancy– Trauma– Postoperative Recovery– Inflammation– Cancer– Rheumatoid Factor– Older Age

• False Negative D-Dimer– Heparin

Prognostic Value of Troponins in AcutePulmonary Embolism

Conclusion: Elevated troponin levels were associated with a high risk of (early) death resulting from pulmonary embolism (OR, 9.44; 95% CI, 4.14 to 21.49)

These findings identify troponin as a promising tool for rapid risk stratification of patients with pulmonary embolism.

BNP & pro-BNP

Typically greater in patients with PE. Sensitivity of 60% and specificity of 62%. At a threshold of 500 pg/mL, the sensitivity of pro-

BNP for predicting adverse events was 95%, and the specificity was 57%.

Kucher N et al. Low pro-brain natriuretic peptide levels predict benign clinical outcome in acute pulmonary embolism. Circulation 2003 Apr 1; 107:1576-8.

WBC Poor sensitivity and nonspecific

Can be as high as 20,000 in some patients

Hb PTE does not alter count but if extreme, consider

polycythemia, a known risk factor

ESR Don’t get one, terrible test in regard to any predictive

value

Doppler ultrasound of leg veins

Principle - Veins are normally compressible; Presence of DVT renders veins non-compressible50% of patients with PE have positive ultrasound(95% of PE are due to leg DVT)

ECG

– 2 Most Common finding on ECG: Nonspecific ST-segment and T-wave changes Sinus Tachycardia

– Historical abnormality suggestive of PE S1Q3T3 Right ventricular strain New incomplete RBBB

Echocardiography

This modality generally has limited accuracy in the diagnosis.

The overall sensitivity and specificity for diagnosis of central and peripheral pulmonary embolism by ECHO is 59% and 77%.

It may allow diagnosis of other conditions that may be confused with pulmonary embolism.

ECHO signs of PE

RV enlargement or hypokinesis especially free wall hypokinesis, with sparing of the apex (the McConnell sign)

60/60 Sign- Acceleration time of RV ejection <60ms in the presence of TR pressure gradient </= 60mmHg.

Interventricular septal flattening and paradoxical motion toward the LV resulting in a “D-shaped” LV in cross section.

Tricuspid regurgitation

Echocardiography

Am J Med 122:257,2009

Echocardiogram in PE

ABG analysis

ABG has a limited role. It usually reveal hypoxemia,

hypocapnia and respiratory alkalosis.

Alveolar arterial oxygen gradient , done at room air, a-a gradient > 15-20 is considered abnormal.

Chest x ray

A normal or nearly normal chest x-ray

Chest Xray

Chest radiograph findings in patient with pulmonary embolism

Result PercentCardiomegaly 27%Normal study 24%Atelectasis 23% Elevated Hemidiaphragm 20%Pulmonary Artery Enlargement 19%Pleural Effusion 18%Parenchymal Pulmonary Infiltrate 17%

Am Heart J 1997;134:479-87

Radiographic signs of acute pulmonary embolism

Signs with relative high specificity but low sensitivity for acute pulmonary embolism:

Decreased vascularity in the peripheral lung (Westermark sign).

Enlargement of the central pulmonary artery (Fleischner sign).

Enlarged right descending pulmonary artery (Palla's sign)

Pleural based areas of increased opacity (Hampton hump).

Hemidiaphragm elevation.

Non specific signs associated with acute pulmonary embolism that may be associated with other diseases:

Focal area of increased opacity. Linear atelectasis. Pleural effusion.

Radiographic signs of acute pulmonary embolism

Westermark’s sign

Westermark sign, with hilar enlargement

Dilatation of pulmonary vessels proximal to embolism along with collapse of distal vessels, often with a sharp cut off.

Hampton’s hump

Hampton’s hump

Dome shaped pleural based opacity due to lung infarction.

Pulmonary infarct is dome shaped instead of being wedge shaped because of double blood supply with preserved bronchial arteries resulting in sparing of the expected apex of the wedge.

Radiographic Eponyms- Hampton’s Hump, Westermark’s Sign

Westermark’s Sign

Hampton’s Hump

Ventilation/Perfusion Scan- “V/Q Scan”

A common modality to image the lung.

Relatively noninvasive.

In many centers remains the initial test of choice

Preferred test in pregnant patients 50 mrem vs 800mrem (with spiral CT)

V/Q ScanVQ scan

Technique

NormalVentilation

Left UL PE

Perfusion scanVentillation scan

Ventilation/Perfusion Scan

HIGH PROBABILITY (>80%): 2 or more large mismatched segments or the equivalent.

any perfusion defect substantially larger than radiographic abnormality

INTERMEDIATE PROBABILITY (20-79%): 1 moderate to 2 large mismatched segments

LOW PROBABILITY (<20%): Non-segmental perfusion defects, matched defects

NORMAL: no perfusion defects

PIOPED: PREDICTIVE VALUE V/Q SCAN

SCAN CATEGORY CLINICAL SUSPICION

80-100% 20-79% 0-19%

HIGH

INTERMEDIATE

LOW

PIOPED INVESTIGATORS. JAMA.1990; 263: 2753-2759

VQ Scan

Spiral CT Major advantage of Spiral CT is speed: Often the patient can hold their breath for

the entire study, reducing motion artifacts. Allows for more optimal use of intravenous

contrast enhancement. Spiral CT is quicker than the equivalent

conventional CT permitting the use of higher resolution acquisitions in the same study time.

Contraindicated in cases of renal disease. Sensitive for PE in the proximal pulmonary

arteries, but less so in the distal segments.

CT Angiogram

Quickly becoming the test of choice for initial evaluation of a suspected PE.

CT unlikely to miss any lesion. Better sensitivity, specificity and can be used directly

to screen for PE. Used to follow up “non diagnostic V/Q scans.

CT Angiogram

Chest computed tomography scanning demonstrating extensive embolization of the pulmonary arteries.

Multidetector Helical CT Pulmonary Angiography

Multidetector Helical CT Pulmonary Angiography Advantages

Multidetector Helical CT Pulmonary Angiography Limitations

CT findings of acute pulmonary embolism

Vascular abnormalities: Intraluminal filling defects that forms an acute

angle with the vessel wall & may be surrounded by contrast material (polo mint sign or railway sign).

Total cutoff of vascular enhancement. Enlargement of the occluded vessel.Ancillary findings: Pleural based wedge shaped areas of increased

attenuation with no contrast enhancement. Linear atelectasis.

Partial eccentric filling defect with acute angle with the vessel wall

Intraluminal filling defect(polo mint sign)

Intraluminal filling defect(railway track sign)

Enlargment of the occluded vessel

Ancillary findings of acute pulmonary embolism(atelectatic band)

MRA

MRA

Pulmonary angiogram

Gold Standard. Positive angiogram provides 100% certainty that an

obstruction exists in the pulmonary artery. Negative angiogram provides > 90% certainty in the

exclusion of PE. “Court of Last Resort”

Pulmonary angiogram

Left-sided pulmonary angiogram showing extensive filling defects within the left pulmonary artery and its branches.

Angiographic severity scoring

Miller, et al. Amer Journ Roent,Rad Therapy & Nuc Med. 125(4):895-9, 1975 Dec.

Further Alternative Imaging Tests (Newer modalities)

Dual-energy CTPA

Electrocardiographically gated CTPA

Three-dimensional images acquired by single-photon emission computed tomography (SPECT) using a gamma-emitting radioisotope may improve V/Q scintigraphy and has a lower radiation dose.

Dual-energy CTPA

Provides functional and anatomic lung imaging Demonstrates perfusion defects beyond obstructive and non-obstructive clots Diagnostic accuracy requires further research

Advantages Indirect evaluation of peripheral pulmonary arterial bed Disadvantages Longer data acquisition time Increased radiation exposure

Dual-energy CTPA

[A] Axial reconstruction with color-coded dual energy perfusion information. Note the large perfusion defects in both lungs.

[B] Coronal reconstruction. Only the apical parts show a normal perfusion.

Electrocardiographically gated CTPA

Can differentiate between cardiac events and PE

May be of use in patients presenting with thoracic pain and suspected PE, cardiac events, or aorta dissection.

More contrast material is needed, and the radiation dose is higher compared with CTPA.

Imaging in Pregnancy

No validated clinical decision rules No consensus in evidence for diagnostic imaging algorithm Balance risk of radiation vs. risk of missed fatal diagnosis or

unnecessary anticoagulation MDCT delivers higher radiation dose to mother but lower

dose to fetus than V/Q scanning Consider low-dose CT-PA or reduced-dose lung scintigraphy

Stein P et al. Radiology. 2007 Jan;242:15-21.Marik PE; Plante LA. N. Engl. J. Med. 2008;359:2025-33.

Imaging-nut shell

Plain chest radiograph – Usually normal and non-specific signs.

Radionuclide ventilation-perfusion lung scan – Excellent negative predictive value.

CT Angiography of the pulmonary arteries – Quickly becoming method of choice.

Pulmonary angiography – Gold standard but invasive.

Diagnostic Tests for Suspected Pulmonary Embolism

Oxygen saturation Nonspecific, but suspect PE if there is a sudden, otherwise unexplained decrement

D-dimer An excellent “rule-out” test if normal, especially if accompanied by non–high clinical probability

Electrocardiography May suggest an alternative diagnosis, such as myocardial infarction or pericarditis

Lung scanning Usually provides ambiguous result; used in lieu of chest CT for patients with anaphylaxis to contrast agent, renal insufficiency, or pregnancy

Chest CT The most accurate diagnostic imaging test for PE ; beware if CT result and clinical likelihood probability are discordant

Pulmonary angiography Invasive, costly, uncomfortable; used primarily when local catheter intervention is planned

Echocardiography Best used as a prognostic test in patients with established PE rather than as a diagnostic test ; many patients with large PE will have normal echocardiograms

Venous ultrasonography Excellent for diagnosis of acute symptomatic proximal DVT; a normal study does not rule out PE because a recent leg DVT may have embolized completely; calf vein imaging is operator dependent

Magnetic resonance Reliable only for imaging of proximal segmental pulmonary arteries; requires gadolinium but does not require iodinated contrast agent

Pulmonary Embolism(Treatment) Part 2

Dr.Tinku JosephDM Resident

Dept. Of Pulmonary MedicineAIMS, Kochi.

Approach to the patient of PE

Stratify patients into high clinical likelihood or non–high clinical likelihood of PE .

In low-risk group, only about 5% of patients were subsequently diagnosed with PE.

How do we work up?- Pretest Probability

Definition: “The probability of the target disorder (PE) before a diagnostic test result is known”.

Used to decide how to proceed with diagnostic testing and final disposition

Classic Wells Criteria to Assess Clinical Likelihood of Pulmonary Embolism

SCORE POINTS

DVT symptoms or signs 3

An alternative diagnosis is less likely than PE

3

Heart rate >100/min 1.5

Immobilization or surgery within 4 weeks

1.5

Prior DVT or PE 1.5

Hemoptysis 1

Cancer treated within 6 months or metastatic

1

>4 score points = high probability ≤4 score points = non–high probability JAMA 295:172,2006

Simplified Wells Criteria to Assess Clinical Likelihood of Pulmonary Embolism

DVT symptoms or signs 1

An alternative diagnosis is less likely than PE

1

Heart rate >100/min 1

Immobilization or surgery within 4 weeks

1

Prior DVT or PE 1

Hemoptysis 1

Cancer treated within 6 months or metastatic

1

>1 score point = high probability ≤1 score point = non–high probability

Thromb Haemost 101:197,2009

Original Geneva score

Revised Geneva score

ACC/AHA Classification

• Massive• Submassive• Low-Risk PE• Pulmonary infarction syndrome

Massive PE

• Acute PE with sustained hypotension (systolic blood pressure 90 mm Hg for at least 15 minutes or requiring inotropic support, not due to a cause other than PE, such as

Arrhythmia Hypovolemia Sepsis Left ventricular (LV) dysfunction Pulselessness Persistent profound bradycardia (heart rate 40 bpm with

signs or symptoms of shock)

Submassive PE• Acute PE without systemic hypotension (systolic blood pressure 90mm Hg)

but with either RV dysfunction or myocardial necrosis• RV dysfunction means the presence of at least 1 of the following RV dilation (apical 4-chamber RV diameter divided by LV diameter 0.9) or

RV systolic dysfunction on echocardiography RV dilation (4-chamber RV diameter divided by LV diameter 0.9) on CT Elevation of BNP (90 pg/mL) Elevation of N-terminal pro-BNP (500 pg/mL) Electrocardiographic changes (new complete or incomplete right bundle-

branch block, anteroseptal ST elevation or depression, or anteroseptal T-wave inversion)

Torbicki A et al. Eur Heart J 29(18):2276–2315, 2008

Low-Risk PE

• Acute PE and the absence of the clinical markers of adverse prognosis that define massive or submassive PE

Pulmonary Infarction Syndrome

• Caused by a tiny peripheral pulmonary embolism Pleuritic chest pain, often not responsive to

narcotics Low-grade fever Leukocytosis Pleural rub Occasional scant hemoptysis

Treatment:

Goals:

Prevent death from a current embolic event

Reduce the likelihood of recurrent embolic events

Minimize the long-term morbidity of the event

Treatment options Symptomatic treatment:

– ABCD approach– Oxygen– Analgesia

Anticoagulation:– IV Heparin– S/C LMWH eg Enoxaparine, Dalteparine– Oral Warfarin

IVC filter: If there is contra-indications for anti-coagulation

Thrombolysis: tPA eg Alteplase, Tenectaplase

Surgical procedures: Pulmonary embolectomy

Treatment options

Massive PE: Thrombolysis/embolectomy

Sub-massive PE: Strongly consider thrombolysis/embolectomy but need to balance risk of bleeding

Non-massive PE: Anticoagulation

KEY STUDIES & guidelines IN PE TREATMENT

• 1937 Murry: first use of heparin• 1960 Barritt:“RCT” warfarin vs. placebo• 1968 Sasahara: UPET• 2003 Konstantinides: Alteplase

Prevention

ACCP guide lines• For acutely ill hospitalised medical pts at low risk of

thrombosis ACCP recommends against the use of prophylaxsis.

• Pts at moderate to high risk but who are not bleeding or at high risk of bleeding should be given either LMWH or UFH or fondaparinux.

Padua Score

Prevention of PE

1 Hospitalization with medical illness

Enoxaparin 40 mg SC qd orDalteparin 5000 units SC qd orFondaparinux 2.5 mg SC qd (in patients with a heparin allergy such as heparin-induced thrombocytopenia) orGraduated compression stockings or intermittent pneumatic compression

2 General surgery Unfractionated heparin 5000 units SC bid or tid orEnoxaparin 40 mg SC qd orDalteparin 2500 or 5000 units SC qd

3 Major orthopedic surgery

Warfarin (target INR 2 to 3) orEnoxaparin 30 mg SC bid orEnoxaparin 40 mg SC qd orDalteparin 2500 or 5000 units SC qd orFondaparinux 2.5 mg SC qdRivaroxaban 10 mg qd (in Canada and Europe)Dabigatran 220 mg bid (in Canada and Europe)

4 Oncologic surgery Enoxaparin 40 mg SC qd

5 Neurosurgery Unfractionated heparin 5000 units SC bid orEnoxaparin 40 mg SC qd andGraduated compression stockings or intermittent pneumatic compressionConsider surveillance lower extremity ultrasonography

6 Thoracic surgery Unfractionated heparin 5000 units SC tid andGraduated compression stockings or intermittent pneumatic compression

Prevention of PE

• For pts who are bleeding or at risk of bleeding use leg compression devices only.

• Pts are considered to be at high risk of bleeding if they meet any of the following criteria

• Active gastrodeodenal ulcer• Bleeding in 3 months prior to admission• Platelet count <50,000

Prevention of PE

Or if they had multiple risk factors for bleeding of lesser predictive strengthlike age >84 yrs,severe renal failure , hepatic failure with INR > 1.5 , male ,current cancer, ICU admission.

Prevention of PE

References Harrison -18 th edition

ACCP guidelines

Fishman's Pulmonary Diseases and Disorders

Crofton and Douglas's Respiratory Diseases (Wiley, 2000)