Transcript Modern Management of Pulmonary Embolism Should I Be

TRAUMA-ICU NURSING
EDUCATIONAL SERIES
PE & DVT:
are we still V-Q scanning ?
Bradley J. Phillips, MD
Critical Care Medicine
Boston Medical Center
Boston University School of Medicine
Pulmonary Embolism
► Pathogenesis
 Vichow’s triad
 Clot dislodgement
 Release of vasoactive substances
►increased
pulmonary vascular resistance
►bronchoconstriction
► Epidemiology
 Incidence = 1/1000 per year
 Mortality (1 year) = 15 %
Risk Factors - Acquired
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Medical
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Prior PE
Age > 40
Obesity
Malignancy
CHF
CVA
Nephrotic Syndrome
Estrogen
Pregnancy
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Surgical
 General anesthesia > 30
minutes
 Hip arthroplasty
 Knee arthroplasty
 Major trauma
 Spinal Cord Injury
 Open prostatectomy
 Neurosurgical procedures
Risk Factors - Hereditary
► Protein
C deficiency
► Protein S deficiency
► Antithrombin III deficiency
► Factor V leiden mutation
Risk Assessment Profile
► Significant
risk in trauma patients
► Risk assessment profile of thromboembolism (RAPT) by
Greenfield
 5 or more (out of 14) increases risk 3 times
►Underlying condition
 Obese, malignancy, hx of thromboembolism
►Iatrogenic factors
 CVL, operations > 2 hrs, major venous repair
►Injury-related factor
 Spinal factures, coma, pelvic fx, plegia
►Age
 > 40 (highest risk > 75)
Diagnosis
Clinical features
► ABG
► Chest X-ray
► EKG
► D-Dimer
►
Lung Scan
► LE doppler
► Spiral CT
► PA catheter
► TTE
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Gold Standard: Pulmonary Angiogram
Clinical Presentation
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Symptoms
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Dyspnea 80%
Apprehension 60%
Pleurisy 60%
Cough 50%
Hemotysis 27%
Syncope 22%
Chest pain
CHF (right)
Hypotension
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Signs
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Tachypnea 88%
Tachycardia 63%
Increased P2 60%
Rales 51%
Pleural rub 17%
Fever
Wheezes
JVD
Cyanosis
Shock
Prospective Investigation of PE Diagnosis: PIOPED
Prospective trial (817 patients)
► Clinical probability - history, PE, CXR, ABG, and EKG
prior to V/Q and pulmonary angiogram
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Results:
Clinical
 High likelihood (>80%)
 Low likelihood (< 20%)
 Indeterminant
Angiogram
32 % negative
9 % positive
30 % positive
Bottom Line: Subtle Manifestations
Clinical features are vague, variable, and nonspecific…
►Unexplained
dyspnea
 Worsening hypoxia or hypocapnia in spontaneously
ventilating patient
 Worsening hypoxia or hypercapnia in a sedated patient on
controlled ventilation
 Worsening dyspnea, hypoxemia, and a reduction in arterial
PCO2 in a patient with COPD and known CO2 retention
ABG’s
► Typical:
hypoxia, hypocarbia, high A-a
► Nonspecific and limited value when used alone
► PIOPED
 normal ABG in 38% (without cardiopulmonary disease)
 normal ABG in 14% (with cardiopulmonary disease)
If present, hypoxia roughly correlates with extent of embolism
as judged by V/Q
CXR
► Essential
for possible Exclusion
► Poor sensitivity and specificity
► PIOPED
 85% of PE had abnormal CXR
►atelectasis
(most common)
►infiltrates
►Other
findings: Hampton’s hump, Westermark’s sign,
enlarged hilum, pleural effusion, cardiomegaly
EKG
► Abnormalities
are common in PE
► Diverse and nonspecific
► Changes
 T-wave inversion (most common)
 “ Classic “ (uncommon, massive PE)
►S1,
Q3, T3
►Pseudo-infarct pattern
►right heart strain
EKG - Predicting PE
► Am
J Cardio, 1994
 49 patients
 seven defined features of ischemia/R strain
 if 3/7 positive, 76 % probably PE
► Chest,
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1997
80 patients
T-wave inversion in one or more precordial
68% of patients with PE
Reversibility with thrombolysis =good outcome
V/Q Scan
► Most
algorithms use V/Q as first step
► PIOPED
 Most value if very low, low, or high probability when
concordant clinical picture
 However, 4x incidence PE with V/Q very low/low
►prolonged
immobilization
►lower limb trauma
►recent surgery
►central venous instrumentation
Probability of PE
Clinical Suspicion
V/Q Scan
Probability (%)
High
High
96
Moderate
High
80
Low
High
50
Low
Low
5
V/Q scan
► PIOPED
(understated)
 majority of patients with suspected PE did not fall into
high probability or normal scan
 majority of patients with PE did not fall into high
probability
 Most patients without PE did not have normal scan
 Significant percentage of patients with intermediate (33%)
and low probability (16%) did have PE by angiogram
V/Q scans - Newer Studies
► Chest,
1996
 223 critically ill patients
 diagnostic utility as accurate as in non-critical patients
► PISA-PED
(1996)
 presence of wedge-shaped defects regardless of size, number,
or ventilation abnormalities
 Grades - normal, near normal, abnormal c/w PE, abnormal
not c/w PE
 Sens. 92%, Spec. 87%
 Selection bias - normal or near-normal no angiogram, abnormal
38% no angiogram
V/Q - Can it be done with the V?
► CXR
+ Q = no less positive or negative predictive value
is high or low probability
► Others studies supportive if scan is read as high or low
probability
► Indeterminant Q scan, requires V scan
► In cardiopulmonary disease, both V/Q scans required
V/Q - COPD
► PE
mimics underlying disease
► V/Q more limited
► Chest , 1992
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108 patients with COPD
60% fell into intermediate
91% fell into intermediate or low
However, high probability or normal
►100%
positive and negative predictive value
V/Q “Final Word”
►A
normal scan essentially r/o PE
► A high probability scan with high clinical suspicious
confirms PE
► Scan with low or intermediate probability should be
considered nondiagnostic
► Perfusion scan alone ok if high probability or normal
Doppler
Valuable role
► Same therapeutic implications as PE
► Criteria for diagnosis
 non-compressible (most accurate)
 presence of echogenic material
 venous distension
 loss of phasicity and augmentation of flow
► Sensitive (95%) in symptomatic thrombosis but not
asymptomatic (30-60%)
► Consider serial exams in indeterminant V/Q
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Doppler and Pelvic Fx
► Proximal
DVT 25-35% of pelvic fx
► Surveillance in asymptomatic patients
 For
►Van Den Berg et al, Intern Angiology, 1999
 Incidence 8.7% trauma patients
 Aside finding: LMWH + stocking better than unfractionated
heparin + stockings (DVT 6% vs. 11.5%, p < 0.05)
 Against
►Schwarz et al, J of Vasc Surg, 2001
 2% incidence of DVT in high-risk trauma patient
 Limited use of surveillance doppler in patient on Lovenox
PA catheter
► If
present at time of PE helpful in diagnosis
► Therapeutic if hemodynamically unstable
► Findings
 normal wedge pressure
 marked elevation in right ventricular and pulmonary
artery pressures
Pulmonary Angiogram
► Virtually
100% sensitive and specific
► Expensive and invasive
► Complications
 5/1111 (0.5%) deaths in PIOPED study
 9/1111 (0.8%) nonfatal complications
 majority of patients were critically ill with sever
compromised cardiopulmonary function before procedure
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“ few would argue against the risk of coronary angiogram in
suspected coronary ischemia, but question often the risk of
pulmonary angiogram for the diagnosis of PE”
Unproven Test
► Echocardiogram
► Spiral
CT scan (literature is building)
► D-Dimer (plus ?)
► MRI (for DVT)
Echocardiogram
► TEE
more sensitive than TTE
► Demonstrate intracardiac clot or signs of right ventricular
failure
► Emboli observed = 42-50% mortality rate
► Indirect evidence
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right ventricular dilation
dilated pulmonary artery
abnl right ventricular wall motion
dilated vena cava
TEE
Sensitivity/Specificity > 90%
► Detects pulmonary truck, right and left main pulmonary
arteries
► Incapable of detecting distal pulmonary emboli
► Valuable in evaluating for other causes i.e. tamponade, R
CHF, dissection
► Positive test is accurate, negative test non-diagnostic
► Primary usefulness unstable patients in ICU setting
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Spiral CT
role is undefined, but emerging as standard of care
in some institutions
► Several
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prospective studies
Sensitive 94%, Specific 96% (Van Rossum, 1996)
Greater sensitivity than V/Q (Mayo, 1997)
Useful in indeterminant V/Q (alternate pathology)
Confident diagnosis higher with CT than V/Q although no
difference in detection (Cross, 1998)
Spiral CT vs V/Q scan
► Advantages
 probably greater sensitivity proximal emboli
 alternate pulmonary pathology
 after hours availability
► Disadvantages
 operator dependent
 lower accuracy for distal emboli
 need for IV contrast ( ? Why not angiogram)
D-Dimer
► Elevated
in >90% of patients with PE
► Rises with intravascular coagulation
► Meta-analysis (29 studies)
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D-dimer alone vs other diagnostic test
Latex agglutination 48-96 % sensitivity
Elisa 88-100% sensitivity
Specificity ranges 10-100 %
D-Dimer
► Perrier,
1996
 normal d-dimer and nondiagnostic V/Q excludes PE
(>90%)
► Egermayer,1998
 parameters
►D-dimer
positive or negative
►PaO2 < or > 80 mmHG
►RR < or > 20
D-Dimer (Egermeyer, 1998)
► Confirmation with
► Predictive
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V/Q scan/ Angiogram
value
D-dimer negative = 0.99
PaO2> 80 = 0.97
RR < 20 = 0.95
D-dimer plus PaO2 = 1.0
► Problems
 Inconsistent confirmation test
 ? Patients with pre-diagnosis PaO2 < 80
D-Dimer
► Critical
deterrents
 problems in development of rapid reproducible
standardized assay
 clinical conditions in ICU can result in accelerated
fibrinolysis and elevated d-dimer
►recent
surgery
►infection
►malignancy
► Bottom-line:
D-dimer useful if negative and V/Q
scan low probability
Management
► Anticoagulation
► Thrombolytic
► IVC
Filter
► Embolectomy
therapy
Anticoagulation
► Heparin/Coumadin
- mainstay therapy
► Alternatives
 Low molecular weight heparin
►no
difference in disease recurrence, death, or major bleeding
►more convenient, but more expensive
►presently not approved by ACOS
 Thrombocytopenia and HIT
►Heparinoids
►Hirudin
►Ancrod
Length of Therapy
► Controversial
► Schulman,
1996
 6 weeks vs 6 months
 former group twice recurrence, no difference hemorrhage
► British
Thoracic Society, 1992
 4 weeks vs 3 months
 former significant higher recurrence and failure of
resolution
 subgroup post-operative DVT/PE no difference
Thrombolysis
► Significantly
accelerated resolution of pulmonary emboli
► No significant difference in mortality but trend in
massive PE
► Complications
 significantly higher hemorrhage rates
 ? Higher stroke rates
►?
role in post-operative patients
 use of lower doses
 7-14 days post surgery reported studies
IVC Filter
► Indications
 ABSOLUTE
►Contraindication
to anticoagulation
►Failure on anticoagulation
 RELATIVE
►relative
contraindication to anticoagulation
►free floating iliocaval thrombus
►compromised pulmonary vasculature
►intention to administer thrombolytic therapy
IVC Filter
► Efficacy
 No large scale prospective trial
►4%
recurrent PE
►3% caval thrombosis
► Complications
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(<10%)
death (0.12%)
filter migration
filter erosion
IVC obstruction
insertion technique
Embolectomy
► Trendelenburg
pioneered surgery for acute PE in
dogs (1920’s)
 No bypass
 Sternotomy
 Partial occlusion clamps applied to pulmonary truck and
cavas occluded
 Incised truck and clot removed
► Predictor
death
of death is preoperative or perioperative
Embolectomy
► Indications
 angiographic evidence of pulm vascular obstruction
(Miller index > 27)
 60% deficit in perfusion scan
 refractory hypotension
 pulmonary hypertension mean > 35 mmHg
Embolectomy
► Kieny,
1991
 reviewed 134 (122 under bypass, 12 modified T-berg)
 30 day survival 84 %
 Deaths
►15%
bypass
►41 % modified T-berg
► Meyer,
1991
 60% survival in 96 patients under bypass
► Percutaneous
extraction (Greenfield)
 76 % success rate, 30 survival 70%
Newer Prevention Strategies?
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Low-weight molecular heparin
 General Surgery
► No
significant difference for overall group
 Orthopedics
► Total
hip and knee arthroplasty
► Spinal cord injury
 Oncologic Surgery
► More
effective than unfractionated heparin
► *Outpatient Prophylaxis (1 month) Bergqvist et al, NEJM,
346(13):975-80, 2002
 Trauma
► Geerts et
al, NEJM, 335:701, 1996
► Knudson et al, J Trauma, 41:446, 1996
► Greenfield et al, J Trauma, 42:100, 1997
Problems with Studies
LMWH and Cancer Surgery
Mismetti et al, British Journal of
Surgery. 88(7):913-30, 2001
LMWH and Trauma
Geerts et al, NEJM, 1996
Trauma and LMWH
Knudson et al, J Trauma, 1996
Trauma and LMWH
Greenfield et al, J Trauma, 1997
Outcomes LMWH in Trauma
► Lower
incidence of DVT
► Bleeding complications low overall
► Only small studies
► Haven’t fully address safety from bleeding
► Bottom-line
 Better prophylaxis in high-risk patients
 Bleeding risk still unknown vs unfractionated heparin
 Mutlicenter trial needed to assess bleeding risk
Summary
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Prevention of DVT/PE
 Identify patients at risk (most if not all surgery patients)
 Methods vary
► Consider
high risk patients for LMWH
► IVC filter in patients you can not anticoagulant
 ? Surveillance doppler in high-risk asymptomatic patients
► Probably
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of benefit in pelvic fractures
PE Diagnosis
 High level of suspicion even if with only symptom is dyspnea
 Spiral CT scan with IV contrast excellent to rule-out proximal PE and
other lung parenchyma disease, but limited
 Consider pulmonary angiogram if suspicion high and other test
equivocal