Pulmonary Embolism (PE) & Deep Vein Thrombosis
REF: Acute Pulmonary Embolism 2008
Deep Vein Thrombosis Diagnosis:
Clinical signs and symptoms are
unreliable for the diagnosis of deep venous thrombosis.
D-dimer assay for DVT screening
See D-Dimer for DVT Screening Algorithm
Contrast venography (only 90% sensitivity
) is the gold standard in the diagnosis of DVT.
Doppler ultrasound imaging of the venous system
has become the procedure of choice for the diagnosis of proximal
leg DVT. The sensitivity is about 89% to 100% and the specificity
is 97% to 100%.
Spiral Chest CT scan to evaluate for
Impedance plethysmography (IPG) has a
sensitivity of 95% and a specificity of 94% for the diagnosis of acute DVT.
Recent studies suggest that the sensitivity and specificity may not
be this high. False-positive IPG studies have been reported when the vasculature
of the leg is engorged in patients who are pregnant or who suffer from severe
congestive heart failure.
Pulmonary angiogram to confirm pulmonary
embolism if indicated clinically (Gold standard)
Radioiodine-labeled fibrinogen - the
sensitivity above the midthigh diminishes rapidly because of background radiation
from the trunk and thus the test is less useful for proximal DVT detection.
In addition, for hip surgery, the surgical field overlaps the area of interest
on the radiofibrinogen scan.
When a radioactive tracer such as Tc-labeled albumin
is injected into a foot vein, external scintillation detectors
can visualize the major veins of the leg. These studies can demonstrate
obstruction of the deep veins, indicating deep venous thrombosis. Because
the perfusion portion of the lung scan is performed with this same material,
nuclear venograms of the leg veins can routinely be done with every perfusion
lung scan. These nuclear venograms
correlate well with contrast venography of the thigh veins and give
additional diagnostic information without adding risk to the routine lung
Proximal thrombi in the popliteal, femoral, and iliac veins often are
associated with pulmonary embolisms. They also obstruct the venous outflow
of the leg and interfere with the normal pressure/volume relationships in
the venous system.
The clinical diagnosis of pulmonary embolism is similarly inaccurate and
requires objective verification.
Three clinical syndromes should alert the physician
to this diagnosis.
Submassive embolism may produce pleuritic pain and hemoptysis. Physical exam
often reveals rales, and chest radiograph shows a parenchymal infiltrate,
pleural effusion, or elevated diaphragm.
Acute cor pulmonale may be caused by obstruction of more than 60% to 75%
of the pulmonary circulation. Patients may present with shock or loss of
consciousness. Chest radiograph is often normal. EKG may show right bundle
branch block or right heart strain but often shows only sinus tachycardia.
Unexplained dyspnea. This may be caused by acute submassive pulmonary embolism
or multiple small pulmonary embolisms over a long period of time. EKG and
chest radiograph may be normal with an acute pulmonary embolism or show signs
of cor pulmonale in the chronic situation, but arterial oxygen tension is
The ventilation/perfusion lung scan
is commonly the first test used to verify the diagnosis.
A high-probability scan was defined as two or more large or moderate
segmental perfusion defects without corresponding ventilation or chest radiograph
abnormalities. Using this criterion alone, an 88% accuracy rate was found
when scans were followed by pulmonary arteriography. If there was a high
clinical suspicion of pulmonary embolism, the accuracy rate rose to 96%.
This degree of accuracy is satisfactory for clinical purposes. Unfortunately,
only 13% of scans showed high-probability type / mismatch, and only 41% of
pulmonary embolism patients had high-probability scans.
Normal or near-normal scans occurred 14% of the time and rarely were
associated with positive pulmonary arteriograms or followup diagnoses of
pulmonary embolisms, although more than 50% of these scans were not followed
by an arteriogram. The combination of a normal or near-normal scan plus a
low clinical index of suspicion for pulmonary embolism correctly ruled out
pulmonary embolism in 98% of patients. This combination occurred in only
8% of the patients. Scan readings other than high probability or normal can
be considered indeterminate, with frequencies of pulmonary embolism ranging
from 16% to 40%.
Pulmonary arteriogram is the gold
standard for the diagnosis of pulmonary embolism, should be done for definitive
diagnosis in the majority of cases.
A normal D-dimer test result is useful in excluding pulmonary embolism
in patients with a low pretest probability of pulmonary embolism or a
nondiagnostic lung scan. Ann Intern Med. 1998;129:1006-1011
Intermittent pneumatic compression (IPC) or Pneumatic plantar compression
Supportive or graduated compression stocking (GCS)
Leg exercise or early ambulation if possible
Enoxaparin (Lovenox) 30 mg q12h
subc (for ortho hip or knee replacement or hip fracture pts)
Heparin 5,000 u subc. q12h (for medical high risk patients)
[Ref: J Critical Illness September 1997, Vol.12, No.9 - R.Phillip Dellinger
PE & DVT Treatment:
Enoxaparin (Lovenox) 1 mg/kg q12h or 1.5 mg/day
Heparin IV for 5-7 days, start with 5000
u units bolus, then IV infusion to achieve PTT of 1.5-2x
Coumadin PO started the first day, keep
INR 2-3 for 3-6 months.
Thrombolytic Rx for PE & DVT
Vena cava Interruption
Streptokinase, urokinase, and tissue plasminogen activator (tPA) have been
extensively studied, although definite indications for their use are
For acute proximal deep venous thrombosis, thrombolytic therapy often results
in marked improvement in leg pain, swelling, and discomfort. Despite early
benefit, it is difficult to prove that thrombolytic therapy provides any
long-term benefit or prevention of postphlebitic syndromes.
Acute iliofemoral vein thrombosis appears to be one indication for
the use of thrombolytic therapy, because the outcome after heparin therapy
alone is so poor.
Early use of thrombolytic therapy for acute pulmonary embolism accelerates
resolution of angiographic and lung scan abnormalities, and pulmonary
hypertension rapidly resolves when compared to heparin therapy. After several
days and at 1 year of followup, little difference can be found between treatment
of pulmonary embolism by heparin or thrombolytic agents. At present, thrombolytic
therapy is recommended only for patients without a tendency to bleed who
have a massive pulmonary embolus, proven by arteriography, which
has caused hemodynamic instability.
Streptokinase should be given as a 250,000-IU
loading dose, followed by 100,000 IU hourly for 24 hours.
Urokinase should be given as a 4400-IU/kg of
body weight loading dose, followed by 2200 IU/kg hourly for 12 hours. For
tPA, infusion of 100 mg over a 2-hour period
is effective for clot lysis. A segmental defect on the pretreatment perfusion
lung scan is associated with a greater degree of improvement after thrombolytic
therapy. There is no advantage to direct delivery of thrombolytic therapy
into the pulmonary circulation. After the infusion of the thrombolytic agent,
heparin therapy should be reinstituted as soon as the aPTT is once again
within therapeutic range (1.5 to 2.0 × control).
Despite reports of better diffusing capacity of the lung at 1 year and better
pulmonary circulatory studies at 7 years followup when compared to heparin
treatment alone, thrombolytic therapy is currently not indicated for all
patients with pulmonary embolism.
For patients with acute pulmonary embolism and the following indications,
vena cava interruption is recommended:
anticoagulation is contraindicated; despite adequate anticoagulation, recurrent
embolization has occurred; anticoagulation must be prematurely discontinued
because of bleeding. A recurrent embolism rate of 5% and a vena caval occlusion
rate of 3% to 5% are certainly acceptable for clinical use. At present, the
stainless steel Greenfield filter appears to be the wisest choice for vena
Surgical embolectomy with
cardiopulmonary bypass is indicated only for those patients with hemodynamic
instability in whom thrombolytic therapy has either failed or is
ACP Library on Disk 2- (c) 1997 - American College of Physicians
Conclusion: Managing patients for suspected pulmonary embolism on the basis
of pretest probability and D-dimer result is safe and decreases the need
for diagnostic imaging.
Intern Med. 2001;135:98-107.
ACP CLINICAL GUIDELINES
DX of DVT 2007
| DVT Rx (KP)
Management of Venous Thromboembolism: A Clinical
from the American College of Physicians and the American Academy of Family
Vincenza Snow, MD; etc.
Annals of Internal Medicine 6 February
2007 | Volume 146 Issue 3
Venous thromboembolism is a common condition affecting 7.1 persons per 10
000 person-years among community residents. Incidence rates for venous
thromboembolism are higher in men and African Americans and increase
substantially with age. It is critical to treat deep venous thrombosis at
an early stage to avoid development of further complications, such as pulmonary
embolism or recurrent deep venous thrombosis. The target audience for this
guideline is all clinicians caring for patients who have been given a diagnosis
of deep venous thrombosis or pulmonary embolism. The target patient population
is patients receiving a diagnosis of pulmonary embolism or lower-extremity
deep venous thrombosis.
Low-molecular-weight heparin (LMWH) rather than
unfractionated heparin should be used whenever possible for the initial inpatient
treatment of deep venous thrombosis (DVT). Either unfractionated heparin
or LMWH is appropriate for the initial treatment of pulmonary embolism.
Consistent evidence demonstrates that LMWH is superior to unfractionated
heparin for the initial treatment of DVT, particularly for reducing mortality
and reducing the risk for major bleeding during initial therapy. Additional
trials are needed to more rigorously examine the efficacy of LMWH for the
initial treatment of pulmonary embolism, but systematic reviews of existing
trials indicate that LMWH is at least as effective as unfractionated heparin
for these patients as well. In addition, trials of unfractionated heparin
in pulmonary embolism show that many patients are subtherapeutic or
supratherapeutic while receiving unfractionated heparin, whereas LMWH is
quickly and consistently therapeutic, an important consideration in the treatment
Outpatient treatment of DVT, and possibly pulmonary
embolism, with LMWH is safe and cost-effective for carefully selected patients
and should be considered if the required support services are in place.
In trials that compared inpatient and outpatient treatment, the rates
of recurrent DVT, major bleeding, and death during follow-up differed only
slightly. These studies were conducted among highly selected groups of patients
and in clinical systems with the required support services in place. Several
studies allowed a brief inpatient admission for stabilization of the patients
before randomization to the outpatient group. While some studies enrolled
patients with concomitant pulmonary embolism, most excluded such patients.
Inclusion criteria were strict: Most studies excluded patients with previous
VTE, thrombophilic conditions, or significant comorbid illnesses; pregnant
patients; and those unlikely to adhere to outpatient therapy. Therefore,
this recommendation cannot be generalized (1).
Compression stockings should be used routinely to
prevent postthrombotic syndrome, beginning within 1 month of diagnosis of
proximal DVT and continuing for a minimum of 1 year after diagnosis.
The evidence demonstrated a marked reduction in the incidence and
severity of postthrombotic syndrome among patients wearing compression stockings,
either over-the-counter stockings or custom-fit stockings, if use was initiated
within 1 month diagnosis of proximal DVT. Most diagnoses of postthrombotic
syndrome occurred early, within the first 2 years after DVT.
There is insufficient evidence to make specific
recommendations for types of anticoagulation management of VTE in pregnant
During pregnancy, women have a 5-fold increased risk for VTE compared
with nonpregnant women. Clinicians should avoid vitamin K antagonists in
pregnant women because these drugs cross the placenta and are associated
with embryopathy between 6 and 12 weeks' gestation, as well as fetal bleeding
(including intracranial hemorrhage) at delivery. Neither LMWH nor unfractionated
heparin crosses the placenta, and neither is associated with embryopathy
or fetal bleeding.
Anticoagulation should be maintained for 3 to 6
months for VTE secondary to transient risk factors and for more than 12 months
for recurrent VTE. While the appropriate duration of anticoagulation for
idiopathic or recurrent VTE is not definitively known, there is evidence
of substantial benefit for extended-duration therapy.
For VTE secondary to transient risk factors, 3 or 6 months of treatment
was associated with similar risks for recurrent VTE. In the single study
that exclusively enrolled patients presenting with a second episode of VTE,
extended-duration (>12 months or indefinite) anticoagulant therapy was
associated with fewer recurrences than was termination after 6 months of
therapy. For patients with idiopathic VTE (including those with recurrent
VTE), extended-duration therapy decreased the relative risk for recurrence
by 64% to 95%. Length of therapy in the trials varied widely, from greater
than 3 months to 12 months to up to 4 years. The results for extended-duration
therapy reflect follow-up only to 4 years; the riskbenefit ratio is
not known for longer durations. Clinicians should weigh the benefits, harms,
and patient preferences in deciding on the duration of anticoagulation.
LMWH is safe and efficacious for the long-term treatment
of VTE in selected patients (and may be preferable for patients with cancer).
Evidence from high-quality randomized trials supports the
use of LMWH as comparable to oral anticoagulation for VTE in selected patients.
Low-molecular-weight heparin may be a useful treatment for patients in whom
control of the international normalized ratio (INR) is difficult and may
be more efficacious than oral anticoagulants in patients with cancer.