pulmonary embolism - (pe)
TRANSCRIPT
Pulmonary EmbolismPulmonary Embolism
Learning OutcomesLearning OutcomesCausesCausesDiagnosisDiagnosisRisk FactorsRisk FactorsTreatmentTreatment
Blood flow to the lungsBlood flow to the lungs Venous system from Venous system from
upper and lower parts upper and lower parts of the body drains into of the body drains into the right atrium and the right atrium and then pumped into the then pumped into the right ventricleright ventricle
The right ventricle The right ventricle pumps blood to the pumps blood to the lungslungs
The Clot TravelsThe Clot Travels So if a clot occurs in any So if a clot occurs in any
vein it will eventually (if it vein it will eventually (if it breaks free) end up in the breaks free) end up in the right side of the heartright side of the heart
The heart then pumps it The heart then pumps it into the pulmonary into the pulmonary arteriesarteries
As the pulmonary artery As the pulmonary artery becomes smaller, the becomes smaller, the blood clot will become blood clot will become caught in the lungs. This caught in the lungs. This is a Pulmonary Embolismis a Pulmonary Embolism
Lung Blood FlowLung Blood Flow Typically there is Typically there is
more flow to the lower more flow to the lower area of the lungs, due area of the lungs, due to gravityto gravity
PEs can occur PEs can occur anywhere in the lung, anywhere in the lung, but more are seen in but more are seen in the lower portion than the lower portion than upper portionupper portion
No preference to No preference to which side it occurswhich side it occurs
Saddle EmbolusSaddle Embolus This is where a clot This is where a clot
occurs at the point of occurs at the point of the pulmonary artery the pulmonary artery branchingbranching
This can be fatal, due This can be fatal, due to the large amount of to the large amount of blood flow that is blood flow that is inhibitedinhibited
Incidence of PEIncidence of PE In the UK, PE occurs in 3-4 per 10 000 In the UK, PE occurs in 3-4 per 10 000
peoplepeople This could be possibly higher as this is This could be possibly higher as this is
only based on clinical dataonly based on clinical data Between 2005-2008 it was mentioned on Between 2005-2008 it was mentioned on
the death certificates of 12 - 13 000 peoplethe death certificates of 12 - 13 000 people It is thought that this figure could be as It is thought that this figure could be as
high as 60 000 per year in the UKhigh as 60 000 per year in the UK(NICE 2013)(NICE 2013)
DiagnosingDiagnosing A large number of A large number of
patients are patients are misdiagnosed and misdiagnosed and only found to have a only found to have a PE on autopsyPE on autopsy
We can test for them We can test for them but results can come but results can come back as negative (or back as negative (or inconclusive)inconclusive)
DiagnosingDiagnosing Most PEs come from Most PEs come from
Deep Venous Deep Venous Thrombosis (DVT)Thrombosis (DVT)
Most DVTs (75%) come Most DVTs (75%) come from the legs, from the legs,
20% of clots embolise 20% of clots embolise with higher incidence with higher incidence above the knee rather above the knee rather than belowthan below
The emboli travel via the The emboli travel via the Inferior Vena Cava (IVC), Inferior Vena Cava (IVC), to the heart, to the lungs to the heart, to the lungs PEPE
In the lungs the blood clot In the lungs the blood clot gets lodged in the gets lodged in the pulmonary artery, so pulmonary artery, so there is no more there is no more perfusion to that area of perfusion to that area of lung, thus ventilation lung, thus ventilation occurs without perfusion occurs without perfusion forming a dead spaceforming a dead space
The blood that should The blood that should have gone to that area is have gone to that area is then diverted to other then diverted to other areas of the lung, this areas of the lung, this causes a V/Q Mismatchcauses a V/Q Mismatch
Lung InfarctLung Infarct There is also an increase There is also an increase
in resistance to blood in resistance to blood flow, this can cause a flow, this can cause a cardiac arrest cardiac arrest
The lungs may infarct, but The lungs may infarct, but this is difficult due to the this is difficult due to the dual blood supply, from dual blood supply, from both the pulmonary artery both the pulmonary artery and also from the aorta, and also from the aorta, as it sends branches to as it sends branches to the lungthe lung
Risk FactorsRisk Factors Orthopaedic Procedure – THR, TKR, #sOrthopaedic Procedure – THR, TKR, #s
Lack of mobilisationLack of mobilisation No thrombo-prophylaxis – TEDS, Flowtrons, No thrombo-prophylaxis – TEDS, Flowtrons,
Dalteparin , Warfarin Dalteparin , Warfarin Abdo / Pelvic surgery - especially for CaAbdo / Pelvic surgery - especially for Ca ObesityObesity Women >30yrs on oral contraceptive who smokeWomen >30yrs on oral contraceptive who smoke Hyper-coaguable state – Protein C & S deficiencies, Hyper-coaguable state – Protein C & S deficiencies,
Factor V LeidenFactor V Leiden PregnancyPregnancy
SymptomsSymptoms May be normalMay be normal TachycardiaTachycardia AFAF Reduced chest movement Reduced chest movement
(due to pain)(due to pain) TachypnoeaTachypnoea Pleural rubPleural rub Haemoptysis (especially in Haemoptysis (especially in
lung infarction)lung infarction) Low grade feverLow grade fever Signs of DVTSigns of DVT PP22 Sound, Sound, Right Heart failure- Right Heart failure- CO, CO,
JVP, JVP, BP and Perfusion BP and Perfusion PressurePressure
DiagnosisDiagnosis ABG – ABG – pH / pH / pCO pCO22/ / pO pO22 (or lower normal range) (or lower normal range) Respiratory AlkalosisRespiratory Alkalosis pOpO22 due to V/Q Mismatch due to V/Q Mismatch pCOpCO22 due to tachypnoea (trying to make room for O due to tachypnoea (trying to make room for O2)2)
AAlveolar-arterial oxygen (A-a) gradient lveolar-arterial oxygen (A-a) gradient PPAAOO22 - P - PaaOO22 Alone they are not diagnostic of pulmonary embolism Alone they are not diagnostic of pulmonary embolism
(PE), but they may be useful in excluding the diagnosis (PE), but they may be useful in excluding the diagnosis of PE if their values fall within the normal range of PE if their values fall within the normal range
AAlveolar-arterial oxygen (A-a) lveolar-arterial oxygen (A-a) gradientgradient
PPAAOO22 - P - PaaOO2 2 should equal (Age (years) / 4) + 4should equal (Age (years) / 4) + 4 PPAAOO2 2 = [(F= [(FiiOO22) x (760 – 47)] – (P) x (760 – 47)] – (PaaCOCO22 / 0.8) / 0.8)
Barometric Pressure = 760mmHgBarometric Pressure = 760mmHg
Water Vapour Pressure = 47mmHgWater Vapour Pressure = 47mmHg
Respiratory Coefficient = 0.8Respiratory Coefficient = 0.8
UseUse PPaaOO2 2 andand PPaaCOCO22 in mmHg not KPa in mmHg not KPa
Eg 40 Yr old, Eg 40 Yr old, FFiiOO22 0.6 0.6 PPaaCOCO2 2 32.5 mmHg32.5 mmHg (4.27KPa)(4.27KPa)PPaaOO2 2 65 mmHg (8.55KPa)65 mmHg (8.55KPa)PPAAOO2 2 =(0.6 x 713) – 40.6 = 387.2=(0.6 x 713) – 40.6 = 387.2PPAAOO22 - P - PaaOO2 2 = 387.2 – 65 = 322.2= 387.2 – 65 = 322.2(40/4) = 10 (+4) = 14 (40/4) = 10 (+4) = 14 Therefore 322.2 > 14Therefore 322.2 > 14So if the A-a gradient > 14 it may be indicative of a PESo if the A-a gradient > 14 it may be indicative of a PE
Chest X-rayChest X-rayChest X ray – most common finding with a Chest X ray – most common finding with a
PE is a normal x-rayPE is a normal x-rayBut they are useful as X-rays help to rule But they are useful as X-rays help to rule
out pneumonia and pneumothorax as out pneumonia and pneumothorax as causes of dyspnoea etccauses of dyspnoea etc
Possible signs indicating a PE are as Possible signs indicating a PE are as followsfollows
Hamptons HumpHamptons Hump Not always seenNot always seen Wedged shaped Wedged shaped
pleural based lesionpleural based lesion PE in one area PE in one area
(Bottom arrow) and (Bottom arrow) and everywhere else is everywhere else is infarctinfarct
Causes pleurisy, Causes pleurisy, irritationirritation
Westermark SignWestermark Sign On this X-ray PE is in On this X-ray PE is in
Left lungLeft lung Increase in blood flow Increase in blood flow
to right side.to right side. Minimal blood flow Minimal blood flow
seen to Left lungseen to Left lung So the side that looks So the side that looks
clearer is the side clearer is the side with reduced blood with reduced blood flow, therefore the clotflow, therefore the clot
ECGECG SSIIQQIIIIIITTIIIIII Can be seen in any Can be seen in any
cor-pulmonale cor-pulmonale syndrome where syndrome where pulmonary artery pulmonary artery systolic pressure is systolic pressure is elevatedelevated
Eg Normal PQRST Eg Normal PQRST
ECGECG Lead Lead II Exaggerated S waveExaggerated S wave
Lead Lead IIIIII Exaggerated Q waveExaggerated Q wave T Wave inversionT Wave inversion
Not specific to PE, but Not specific to PE, but gets you to possibly gets you to possibly think of the diagnosisthink of the diagnosis
ECG – Precordial LeadsECG – Precordial Leads Peaked T wavesPeaked T waves V1-V4V1-V4 Makes you think about :-Makes you think about :-
Right Heart Strain, Right Heart Strain, PE, Cor-pulmonalePE, Cor-pulmonale
Tachycardia nearly Tachycardia nearly always seen in PE but always seen in PE but also most other problems also most other problems so non-specificso non-specific
D-dimerD-dimer By-product of fibrin By-product of fibrin
degradationdegradation As clot degraded by As clot degraded by
enzymes, Fibrin enzymes, Fibrin Degradation Products Degradation Products (FDP) are released, one (FDP) are released, one of these is the D-dimerof these is the D-dimer
Little clots in body release Little clots in body release D-dimers, therefore if test D-dimers, therefore if test +ve - do not know if it is +ve - do not know if it is from a PE, from a PE,
But test is so sensitive But test is so sensitive that if no D-dimer ( –ve) that if no D-dimer ( –ve) you can rule out PEyou can rule out PE
UltrasoundUltrasound Non-invasive Non-invasive Looks at lower limbsLooks at lower limbs Doppler USS looks at Doppler USS looks at
vein for flow and vein for flow and compressibilty to see compressibilty to see if clot presentif clot present
USS ResultsUSS Results If +ve for DVT and patient has If +ve for DVT and patient has
respiratory distress symptoms respiratory distress symptoms you can rule in a PE, since the you can rule in a PE, since the DVTs can embolise easily and DVTs can embolise easily and enter the lungs causing enter the lungs causing respiratory problemsrespiratory problems
If -ve for DVT, unsure whether If -ve for DVT, unsure whether there is a PE or not, as a clot there is a PE or not, as a clot from other part of body may from other part of body may have embolised the lung, or a have embolised the lung, or a whole DVT may have travelled whole DVT may have travelled to the lungto the lung
So a –ve result does not give a So a –ve result does not give a thorough answer, whilst a +ve thorough answer, whilst a +ve result may rule it inresult may rule it in
ECHOECHO Sometimes beneficialSometimes beneficial The right ventricle The right ventricle
pumps blood to lungs pumps blood to lungs If clot is present the If clot is present the
pressure at site of clot pressure at site of clot increases and so increases and so does the pressure in does the pressure in the right ventriclethe right ventricle
ECHOECHO The severity of this Pulmonary The severity of this Pulmonary
Artery Pressure (PAP) and the Artery Pressure (PAP) and the severity of the clot, is found by severity of the clot, is found by looking at the tricuspid valve looking at the tricuspid valve and noting how much regurge and noting how much regurge occurs (Tricuspid jet)occurs (Tricuspid jet)
If tricuspid jet is high then PAP If tricuspid jet is high then PAP differential between RA and differential between RA and RV is great and the clot burden RV is great and the clot burden is largeis large
All these tests may help in the All these tests may help in the possible diagnosis of a PE, but possible diagnosis of a PE, but are not definitive testsare not definitive tests
VQ ScanVQ Scan Nuclear medicine scanNuclear medicine scan Looks at perfusion and ventilationLooks at perfusion and ventilation In pneumonia for example, you would get In pneumonia for example, you would get
decreased perfusion and decreased ventilation decreased perfusion and decreased ventilation due to the purulent material present this is a due to the purulent material present this is a “Matched Deficit”“Matched Deficit”
In a PE there is decreased perfusion of the lung In a PE there is decreased perfusion of the lung in the area but ventilation remains the same this in the area but ventilation remains the same this is an “Unmatched Deficit”is an “Unmatched Deficit”
Does Not affect patient in renal failureDoes Not affect patient in renal failure Impaired view if patient has pneumonia etcImpaired view if patient has pneumonia etc
VQ ScanVQ Scan The patients ventilation is The patients ventilation is
assessed by them assessed by them breathing in Xenonbreathing in Xenon
For perfusion the patient For perfusion the patient is injected with Technigas is injected with Technigas (T(Tcc99mMAA)99mMAA)
Use Gamma Camera (a Use Gamma Camera (a glorified Geiger counter) glorified Geiger counter) to measure the nuclear to measure the nuclear materialmaterial
Probability of PEProbability of PE Normal - Full ventilation Normal - Full ventilation
and perfusion seenand perfusion seen Low Pobability for PE – Low Pobability for PE –
(<20%)(<20%) Intermediate probability Intermediate probability
for PE- for PE- V and V and P in P in same areasame area(Matched deficit) (20-(Matched deficit) (20-80%)80%)
High Probability for PE – High Probability for PE – Normal V and Normal V and P (Un-P (Un-Matched deficit) (>80%)Matched deficit) (>80%)
CTPACTPA Contrast injected into body, Contrast injected into body, CT Scan obtained as this is CT Scan obtained as this is
occurringoccurring Vessels viewed on end and Vessels viewed on end and
seen if they light up with seen if they light up with contrast.contrast.
If only partially light up with If only partially light up with contrast there may be a blood contrast there may be a blood clot present stopping flowclot present stopping flow
Do not use if in renal failure Do not use if in renal failure ((Creatanine) (could use Creatanine) (could use HCOHCO33 cover to stop cover to stop nephrotoxic effect of contrast)nephrotoxic effect of contrast)
Unlike VQ Scan if patient has Unlike VQ Scan if patient has a pneumonia it will not affect a pneumonia it will not affect resultsresults
CTPACTPA In 2006 ‘The Christopher Study’ showed that if In 2006 ‘The Christopher Study’ showed that if
you perform a CTPA that was negative for a you perform a CTPA that was negative for a blood clot with a –ve D-dimer result, it was blood clot with a –ve D-dimer result, it was shown to be safe to withhold anticoagulation, shown to be safe to withhold anticoagulation, this supports the reasoning that you should not this supports the reasoning that you should not do a repeat CT scan if first found to be –ve for a do a repeat CT scan if first found to be –ve for a clotclot
The CTPA is the test of choice for diagnosis of The CTPA is the test of choice for diagnosis of PE, if unable to perform this due to PE, if unable to perform this due to Creatanine, the next choice would be a VQ Creatanine, the next choice would be a VQ Scan. Scan.
BUT, these are not the ‘Gold Standard’BUT, these are not the ‘Gold Standard’
Gold StandardGold Standard Pulmonary Angiogram – Pulmonary Angiogram –
Most accurate test, but Most accurate test, but not always best for not always best for patient (most invasive)patient (most invasive)
Catheter inserted into Catheter inserted into right side of the heart, right side of the heart, dye is injected directly dye is injected directly into pulmonary artery, into pulmonary artery, observed under observed under fluoroscopyfluoroscopy
Dangerous, Dangerous, mortality rate, mortality rate,
especially in patients with especially in patients with PEPE
TreatmentTreatment AnticoagulationAnticoagulation Eg Warfarin / HeparinEg Warfarin / Heparin
-Blood thinning-Blood thinning-Prevent new clots-Prevent new clotsNon-thrombolytic Non-thrombolytic treatment treatment
ThrombolyticsThrombolytics-Dissolve Clot, -Dissolve Clot, -not solely used for -not solely used for PE treatmentPE treatment
DVT Treatment 3-6 monthsDVT Treatment 3-6 months PE Treatment 6-9 monthsPE Treatment 6-9 months
IVC FilterIVC Filter
If anticoagulation If anticoagulation treatment treatment contraindicated contraindicated IVC IVC FilterFilter
If clot travels it gets If clot travels it gets caught in IVC Filtercaught in IVC Filter
IVC FilterIVC Filter It is possible for blood clot to be caught and It is possible for blood clot to be caught and
develop in IVC filterdevelop in IVC filter Cochrane Collaboration recommends IVC forCochrane Collaboration recommends IVC for1.1. Recurrent PE despite use of anticoagulation, Recurrent PE despite use of anticoagulation,
or in absolute contra-indication to or in absolute contra-indication to anticoagulationanticoagulation
2.2. Proximal DVT with massive pulmonary Proximal DVT with massive pulmonary thrombosis – next one could kill patientthrombosis – next one could kill patient
3.3. Trauma Patient – needing operationTrauma Patient – needing operation
AnticoagulationAnticoagulation Ideally start Fast acting and slow acting anticoagulants, Ideally start Fast acting and slow acting anticoagulants,
when slow acting anticoagulants at desired level, stop when slow acting anticoagulants at desired level, stop fast actingfast acting
Fast acting -Heparin productsFast acting -Heparin productsHeparin (IV) orHeparin (IV) orLow Molecular Weight Heparin (S/C)Low Molecular Weight Heparin (S/C)
Slow acting – Vitamin K AntagonistsSlow acting – Vitamin K AntagonistsWarfarinWarfarin
Fast ActingFast Acting Heparin productsHeparin products
IV Heparin IV Heparin Aim for therapeutic APTTAim for therapeutic APTTCan be started Can be started immediatelyimmediatelyQuick Anticoagulation Quick Anticoagulation actionactionIf bleeding occurs can If bleeding occurs can stop it and reduced stop it and reduced effects occur within few effects occur within few hours as it has a short hours as it has a short half life (45-60min)half life (45-60min)
Heparin Induced Heparin Induced ThrombocytopaeniaThrombocytopaenia
Can cause highest incidence of HITCan cause highest incidence of HIT-Usually occurs 5-14 days after starting -Usually occurs 5-14 days after starting Heparin Heparin (even if discontinued) or sooner if previously had (even if discontinued) or sooner if previously had heparinheparin-Immune response to heparin-Immune response to heparin
-Antibodies combine with heparin and platelets -Antibodies combine with heparin and platelets causing causing platelet activation of microparticles platelet activation of microparticles which which initiate the initiate the formation of blood clots; the platelet formation of blood clots; the platelet count falls as a count falls as a result, So,result, So,-Platelet count drops by >50%-Platelet count drops by >50%-Get hyper-coaguable state, get more clotting -Get hyper-coaguable state, get more clotting even even though platelet count lowthough platelet count low-If this occurs change from heparin products-If this occurs change from heparin products
Fast ActingFast Acting Low Molecular Weight Heparin (SC)Low Molecular Weight Heparin (SC)
Eg clexane, dalteparin, fondaparinuxEg clexane, dalteparin, fondaparinuxGive twice per day dependent on Creatanine Clearance Give twice per day dependent on Creatanine Clearance
(CrCl) (CrCl) (20-29ml/min)(20-29ml/min)Or if CrCl ≥30ml/min give once a dayOr if CrCl ≥30ml/min give once a dayProblem is if given, anticoagulation is present for next 12 or Problem is if given, anticoagulation is present for next 12 or 24hrs (as half life is four times as long as heparin, about 4 24hrs (as half life is four times as long as heparin, about 4
hrs)hrs)Incidence of HIT is lower than IV HeparinIncidence of HIT is lower than IV HeparinEasy and quick to administerEasy and quick to administer
Also available is rivaroxaban, a fast acting oral medication, Also available is rivaroxaban, a fast acting oral medication, The The effects lasts 8 to 12 hours, but factor Xa activity does not return to effects lasts 8 to 12 hours, but factor Xa activity does not return to normal within 24 hours so once-daily dosing is possible. normal within 24 hours so once-daily dosing is possible.
To work out CrClTo work out CrCl Takes into account Takes into account
Patients Age, Gender, Patients Age, Gender, Ideal Weight (Kg) Serum Ideal Weight (Kg) Serum Creatanine (Creatanine (μμmol/L) from mol/L) from last 24hrslast 24hrs
Use the equationUse the equation((140-Age) x (ideal weight) / ((140-Age) x (ideal weight) /
Cr) x1.23(male) = CrClCr) x1.23(male) = CrCl((140-Age) x (ideal weight) / ((140-Age) x (ideal weight) /
Cr) x1.04(female) = CrClCr) x1.04(female) = CrClUse STH treatment of Use STH treatment of
Thromboembolic Disease Thromboembolic Disease Dalteparin Prescription Dalteparin Prescription ChartChart
ExamplesExamplesEg Age 67 yrsEg Age 67 yrsGender - MaleGender - MaleIdeal Weight 85KgIdeal Weight 85KgCr 73 Cr 73 μμmol/Lmol/LEg (140-67 = 73) Eg (140-67 = 73) 73 x 85 = 6205 73 x 85 = 6205 6205/ 73 =85 6205/ 73 =85 85 x 1.23 = 104.ml/min85 x 1.23 = 104.ml/minSo, 18 000 iu Dalteparin once per day as CrCl > 30ml/minSo, 18 000 iu Dalteparin once per day as CrCl > 30ml/min
Age 85 yrsAge 85 yrsGender – FemaleGender – FemaleIdeal Weight 60KgIdeal Weight 60KgCr – 160 Cr – 160 μμmol/Lmol/L(140-85 = 55) (140-85 = 55) 55 x 60 = 3300 55 x 60 = 3300 3300 / 160 = 20.6 3300 / 160 = 20.6 20.6 x 1.04 = 20.6 x 1.04 =
21.24ml/min21.24ml/minSo, 5000iu Dalteparin am and 5000iu Dalteparin pm as CrCl 20-29ml/minSo, 5000iu Dalteparin am and 5000iu Dalteparin pm as CrCl 20-29ml/min
If patient weighed more than 100Kg split dose if CrCl If patient weighed more than 100Kg split dose if CrCl ≥30ml/min≥30ml/min
Slow ActingSlow Acting Slow – Vitamin K antagonistsSlow – Vitamin K antagonists
eg warfarin 5mg po odeg warfarin 5mg po odAffects factors 2, 7, 9, 10, C and SAffects factors 2, 7, 9, 10, C and SIf started on 10mg po od can get a drop in If started on 10mg po od can get a drop in protein C and S (shortest acting vitamin K protein C and S (shortest acting vitamin K dependent factors), which can cause a dependent factors), which can cause a
hyper-coaguable statehyper-coaguable stateTakes 2-3 days to reach desired level Takes 2-3 days to reach desired level
shown shown by INR of 2-3by INR of 2-3If any medication changes, check INR as If any medication changes, check INR as
can can be affectedbe affected
PreventionPrevention Bilateral Lower Extremity Bilateral Lower Extremity
Sequential Compression Sequential Compression DevicesDevices
TEDs and FlowtronsTEDs and FlowtronsWhen the legs are When the legs are
squeezed the veins release a squeezed the veins release a factor which thins the blood factor which thins the blood stopping clot formation, stopping clot formation, the rhythmic motion copies the rhythmic motion copies that of leg movementthat of leg movement
ThromboprophylaxisThromboprophylaxisDalteparinDalteparin
Genetic Blood TestsGenetic Blood Tests 25-50% of patients with VTE have an inherited disorder25-50% of patients with VTE have an inherited disorder There are genetic causes of metabolism which may be tested forThere are genetic causes of metabolism which may be tested for- Factor V Leiden – causes increased clotting as variant cannot be Factor V Leiden – causes increased clotting as variant cannot be
inactivated by Factor Protein C (5% of popinactivated by Factor Protein C (5% of popn n and 20% of pts with and 20% of pts with thrombus)thrombus)
- Factor Protein C Deficiency – results in normal cleaving of Factor Factor Protein C Deficiency – results in normal cleaving of Factor Va and Factor VIIIaVa and Factor VIIIa
- 20210 (prothrombin) Mutation – 2-3 times risk of clot formation20210 (prothrombin) Mutation – 2-3 times risk of clot formation- MTHMFR affects regulation of homocysteineMTHMFR affects regulation of homocysteine- Lupus anticoagulant- prothrombotic agent which can cause Lupus anticoagulant- prothrombotic agent which can cause
inappropriate clottinginappropriate clotting- Anti phospholipid antibody – confused autoimmune responseAnti phospholipid antibody – confused autoimmune response
If any of these are positive and patient has a clot then may need If any of these are positive and patient has a clot then may need treatment for longertreatment for longer
So, RememberSo, Remember