Title: PE
1 PE DVT are we still V-Q scanning ?
TRAUMA-ICU NURSING EDUCATIONAL SERIES
- Bradley J. Phillips, MD
- Critical Care Medicine
- Boston Medical Center
- Boston University School of Medicine
2Pulmonary Embolism
- Pathogenesis
- Vichows triad
- Clot dislodgement
- Release of vasoactive substances
- increased pulmonary vascular resistance
- bronchoconstriction
- Epidemiology
- Incidence 1/1000 per year
- Mortality (1 year) 15
3Risk Factors - Acquired
- Medical
- Prior PE
- Age gt 40
- Obesity
- Malignancy
- CHF
- CVA
- Nephrotic Syndrome
- Estrogen
- Pregnancy
- Surgical
- General anesthesia gt 30 minutes
- Hip arthroplasty
- Knee arthroplasty
- Major trauma
- Spinal Cord Injury
- Open prostatectomy
- Neurosurgical procedures
4Risk Factors - Hereditary
- Protein C deficiency
- Protein S deficiency
- Antithrombin III deficiency
- Factor V leiden mutation
5Risk 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 gt 2 hrs, major venous repair
- Injury-related factor
- Spinal factures, coma, pelvic fx, plegia
- Age
- gt 40 (highest risk gt 75)
6Diagnosis
- Clinical features
- ABG
- Chest X-ray
- EKG
- D-Dimer
- Lung Scan
- LE doppler
- Spiral CT
- PA catheter
- TTE
Gold Standard Pulmonary Angiogram
7Clinical Presentation
- Symptoms
- Dyspnea 80
- Apprehension 60
- Pleurisy 60
- Cough 50
- Hemotysis 27
- Syncope 22
- Chest pain
- CHF (right)
- Hypotension
- Signs
- Tachypnea 88
- Tachycardia 63
- Increased P2 60
- Rales 51
- Pleural rub 17
- Fever
- Wheezes
- JVD
- Cyanosis
- Shock
8Prospective Investigation of PE Diagnosis PIOPED
- Prospective trial (817 patients)
- Clinical probability - history, PE, CXR, ABG, and
EKG prior to V/Q and pulmonary angiogram - Results
-
- High likelihood (gt80) 32 negative
- Low likelihood (lt 20) 9 positive
- Indeterminant 30 positive
Clinical Angiogram
9Bottom 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
10ABGs
- 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
11CXR
- Essential for possible Exclusion
- Poor sensitivity and specificity
- PIOPED
- 85 of PE had abnormal CXR
- atelectasis (most common)
- infiltrates
- Other findings Hamptons hump, Westermarks
sign, enlarged hilum, pleural effusion,
cardiomegaly
12EKG
- 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
13EKG - Predicting PE
- Am J Cardio, 1994
- 49 patients
- seven defined features of ischemia/R strain
- if 3/7 positive, 76 probably PE
- Chest, 1997
- 80 patients
- T-wave inversion in one or more precordial
- 68 of patients with PE
- Reversibility with thrombolysis good outcome
14V/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
15Probability of PE
Clinical Suspicion V/Q Scan Probability
() High High 96 Moderate
High 80 Low High 50 Low
Low 5
16V/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
17V/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
18V/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
19V/Q - COPD
- PE mimics underlying disease
- V/Q more limited
- Chest , 1992
- 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
20V/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
21Doppler
- 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
22Doppler 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 lt 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
23PA 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
24Pulmonary 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 - 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
25Unproven Test
- Echocardiogram
- Spiral CT scan (literature is building)
- D-Dimer (plus ?)
- MRI (for DVT)
26Echocardiogram
- TEE more sensitive than TTE
- Demonstrate intracardiac clot or signs of right
ventricular failure - Emboli observed 42-50 mortality rate
- Indirect evidence
- right ventricular dilation
- dilated pulmonary artery
- abnl right ventricular wall motion
- dilated vena cava
27TEE
- Sensitivity/Specificity gt 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
28Spiral CT
- role is undefined, but emerging as standard of
care - in some institutions
- Several 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)
29Spiral 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)
30D-Dimer
- Elevated in gt90 of patients with PE
- Rises with intravascular coagulation
- Meta-analysis (29 studies)
- D-dimer alone vs other diagnostic test
- Latex agglutination 48-96 sensitivity
- Elisa 88-100 sensitivity
- Specificity ranges 10-100
31D-Dimer
- Perrier, 1996
- normal d-dimer and nondiagnostic V/Q excludes PE
(gt90) - Egermayer,1998
- parameters
- D-dimer positive or negative
- PaO2 lt or gt 80 mmHG
- RR lt or gt 20
32D-Dimer (Egermeyer, 1998)
- Confirmation with V/Q scan/ Angiogram
- Predictive value
- D-dimer negative 0.99
- PaO2gt 80 0.97
- RR lt 20 0.95
- D-dimer plus PaO2 1.0
- Problems
- Inconsistent confirmation test
- ? Patients with pre-diagnosis PaO2 lt 80
33D-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
34Management
- Anticoagulation
- Thrombolytic therapy
- IVC Filter
- Embolectomy
35Anticoagulation
- 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
36Length 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
37Thrombolysis
- 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
38IVC 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
39IVC Filter
- Efficacy
- No large scale prospective trial
- 4 recurrent PE
- 3 caval thrombosis
- Complications (lt10)
- death (0.12)
- filter migration
- filter erosion
- IVC obstruction
- insertion technique
40Embolectomy
- Trendelenburg pioneered surgery for acute PE in
dogs (1920s) - No bypass
- Sternotomy
- Partial occlusion clamps applied to pulmonary
truck and cavas occluded - Incised truck and clot removed
- Predictor of death is preoperative or
perioperative death
41Embolectomy
- Indications
- angiographic evidence of pulm vascular
obstruction (Miller index gt 27) - 60 deficit in perfusion scan
- refractory hypotension
- pulmonary hypertension mean gt 35 mmHg
42Embolectomy
- 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
43Newer Prevention Strategies?
- 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, 335701, 1996
- Knudson et al, J Trauma, 41446, 1996
- Greenfield et al, J Trauma, 42100, 1997
44Problems with Studies
45LMWH and Cancer Surgery
Mismetti et al, British Journal of Surgery.
88(7)913-30, 2001
46LMWH and Trauma
Geerts et al, NEJM, 1996
47Trauma and LMWH
Knudson et al, J Trauma, 1996
48Trauma and LMWH
Greenfield et al, J Trauma, 1997
49Outcomes LMWH in Trauma
- Lower incidence of DVT
- Bleeding complications low overall
- Only small studies
- Havent 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
50Summary
- 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 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