Pulmonary Embolism

Question 1

how does a PE happen?

Answer 1

deep vein thrombosis migrates to the pulmonary arterial tree

Question 2

massive PE

Answer 2

acute PE with obstructive shock or SBP <90 mmHg

Question 3

submassive PE

Answer 3

acute PE without systemic hypotension (SBP ≥90 mm Hg) but with either RV dysfunction or myocardial necrosis

Question 4

non-massive PE

Answer 4

low risk

Question 5

PE pathophysiology

Answer 5

Increased PVR -> RVF -> obstructive shock
Increased alveolar dead space -> V/Q mismatch -> pulmonary vasoconstriction to optimize gas exchange
Pulmonary infarction
Chronic pulmonary hypertension can ensue

(PVR= pulmonary vascular resistance; RVF= right ventricular failure)

Question 6

clinical features of PE on hx

Answer 6

May be asymptomatic
SOB
Pleuritic chest pain
Apprehension
Cough
Haemotypsis
Leg pain
Collapse = massive PE
Acute cardiovascular collapse

Question 7

clinical signs of PE

Answer 7

Pale, mottled skin
Tachypnoea
Tachycardia
Signs of DVT
Hypotension
Altered LOC
Elevated JVP
Parasternal heave
Loud P2
Central cyanosis

Question 8

major risk factors for PE

Answer 8

SLOMMP

• surgery
• lower limb problems
• obstetrics
• malignancy
• mobility
• previous thrombosis

Question 9

minor PE risk factors

Answer 9

COM
- CVS
- oestrogens
- Miscellaneous – COPD, neurological disability, occult malignancy, thrombotic disorder, long distance travel, obesity, other (IBD, nephrotic syndrome, dialysis, myeloproliferative disorders, paroxysmal nocturnal haemoglobinuria, Bechet’s disease)

Question 10

thrombophilias to consider

Answer 10

Factor V Leiden mutation
Prothrombin gene mutation
Hyperhomocysteinaemia
Antiphospholipid antibody syndrome
Deficiency of antithrombin III, protein C or protein S
High concentrations of factor VIII or XI
Increased lipoprotein (a)
-> test in those < 50years with recurrent or a strong FHx

Question 11

how is severity assessed in PE?

Answer 11

> haemodynamic status
Clinical markers

Shock
Hypotension – Defined as a systolic blood pressure of <90 mmHg or a pressure drop of >40 mmHg for >15 min

Question 12

right ventricular dysfunction and haemodynamic compromise not due to a cause other than PE

Answer 12

massive PE

Question 13

right ventricular strain or myocardial necrosis without haemodynamic compromise

Answer 13

sub-massive PE

Question 14

not associated with right ventricular strain, myocardial necrosis or haemodynamic compromise

Answer 14

non-massive PE

Question 15

Markers of right ventricular dysfunction

Answer 15

RV dilatation, hypokinesis or pressure load on echocardiography
RV dilation on spiral CT
BNP or NT-proBNP elevation

Question 16

markers of myocardial injury

Answer 16

Cardiac Trop T or I positive

Question 17

ECG findings in PE - see table

Answer 17

Dilation of the right atrium and right ventricle with consequent shift in the position of the heart.
Right ventricular ischaemia.
Increased stimulation of the sympathetic nervous system due to pain, anxiety and hypoxia.

Question 18

see table for other investigations

Question 18

considerations in a pregnant patient

Answer 18

Both CTPA and V/Q scans expose the fetus to low levels of radiation and are thus equivocal in this regard.

CTPA exposes the breast tissue to higher levels of radiation when compared to V/Q scans.

V/Q scans are the preferred imaging modality in centres where both modalities are available.

If you suspect a PE in a pregnant patient then a shielded CXR and a lower limb ultrasound should be the initial investigations performed.
Ultrasound is safe and non-invasive.

If the patient has a DVT and clinical signs that suggest PE then treatment should be commenced and no further imaging is required.

If the patient has asthma or COPD or if you have no access to a V/Q scan then a CTPA should be performed.

Question 18

PERC

Answer 18

Low risk of PE (decided either through clinical evaluation or low risk Wells)
Is the patient older than 49 years of age?
Is the pulse rate above 99 beats min?
Is the pulse oximetry reading <95% while the patient breathes room air?
Is there a present history of hemoptysis?
Is the patient taking exogenous estrogen?
Does the patient have a prior diagnosis of venous thromboembolism (VTE)?
Has the patient had recent surgery or trauma? (Requiring endotracheal intubation or hospitalisation in the previous 4 weeks.).
Does the patient have unilateral leg swelling?

—-> investigate more if yes to any

Question 19

see wells score

Question 19

mx for submassive PE

Answer 19

Strongly consider thrombolysis/embolectomy but need to balance risk of bleeding. Controversy exists over whether thrombolytics are of benefit in this group. Doesn’t reduce mortality but does reduce deterioration
Local guidance should be followed and specialist advice sought

Question 20

mx for massive PE

Answer 20

thrombolyse/embolectomy.
Inotropic support is often required. After checking for contraindications, thrombolytics are indicated.

Question 21

mx for low risk PE

Answer 21

anti-coagulation

Question 22

ABC

Answer 22

A – may need intubation if in cardiovascular collapse or cardiac arrest B – high flow O2 as a pulmonary vasodilator, ventilation to optimize V/Q mismatch, hyperventilation to clear CO2 C – invasive monitoring, fluid management to optimize right ventricular function, inotropic support, cautious fluid boluses, use milrinone, noradrenaline or adrenaline (rather than alpha agonists) as inotropes

Question 23

Thrombolysis

Answer 23

A. tPA (alteplase)* 100mg (0.6mg/kg) over 120 minutes followed by anticoagulation B. Streptokinase 1 million units over 24 hours *Drugs of choice* Not used in non-massive or low risk PEs Can be used up to 14 days after symptoms begin PE resolve more quickly than with heparin alone As successful as embolectomy in massive PE (earlier the better) Indicated in patients with RV compromise + haemodynamically unstable contraindications: absolute – bleeding, recent stroke, HI, current GI bleeding, relative – PUD, surgery within 7 day, prolonged CPR If bleeds -> FFP and anti-fibrinolytics

Question 24

Thrombolysis contraindications

Answer 24

absolute – bleeding, recent stroke, HI, current GI bleeding relative – PUD, surgery within 7 day, prolonged CPR

Question 25

how to rectify a bleed after thrombolytics

Answer 25

FFP --> then anti-fibrinolytics

Question 26

Anti-coagulation

Answer 26

A. Enoxaparin 1mg/kg SC 12 hourly 2. Heparin 80 units/kg IV bolus, followed by 18 units/kg/hour IV infusion *Drugs of choice* Start immediately when there is a suspicion (prior to imaging) LMWH as good as heparin Give straight after thrombolysis Then needs warfarin (INR 2-3)

Question 27

surgical rx

Answer 27

embolectomy (massive PE and unresponsive to thrombolysis or is contraindicated) right heart catheterization with clot destruction IVC filter (high risk of further embolic or recurrent PE despite adequate anticoagulation, contraindications to anticoagulation, extensive DVT, massive PE) UNDERLYING CAUSE prophylaxis modify risk factors diagnose thrombophillias

Question 27

admission criteria in PE

Answer 27

1. Admit all patients with PE for anticoagulation and observation. 2. Start warfarin on day 1 or 2 of LMWH or unfractionated heparin therapy and overlap until desired INR (2.0-3.0), THEN discontinue heparin. Clinically stable patients with a high suspicion for PE, no contraindications to coagulation, and a lack of imaging availabilities should be admitted, anticoagulated and studied when resources are available in the morning. Unstable patients need to be admitted to a HCU/ICU. Refer as needed.

Question 27

prevention measures

Answer 27

Identify patients at risk Mechanical – Compression stockings or pneumatic compression devices Chemical – Enoxaparin 40mg SC once daily or heparin 5000 IU SC 8 hourly. Renal adjusted doses should be considered in acute/ chronic kidney injury as per SAMF guidance.

Question 28

discharge criteria for PE

Answer 28

> Patient needs to be haemodynamically stable > Any concomitant conditions under control > INR must be therapeutic > Social situation adequate