• A haemodynamically unstable pulmonary embolism (PE) with a systolic BP <90 mmHg or a drop in systolic blood pressure of ≥40 mmHg
• If after initial resuscitation, BP does not meet the above criteria, treat as haemodynamically stable PE - see Pulmonary embolism: Haemodynamically stable guideline

Massive PE highly likely if:

• Collapse/hypotension
• Unexplained hypoxia
• Engorged neck veins
• Right ventricular gallop (often)
• Cardiac arrest

• Urgent CTPA and echocardiogram
• D-dimer is not relevant in haemodynamically unstable PE

Cardiac arrest

• Resuscitation (CPR). See CPR - Procedure guideline
• Give alteplase 50 mg IV as bolus injection
• CTPA or echocardiogram confirmation not required
• Reassess after 30 min

General

• Oxygen - see Hypoxaemia guideline
• Adequate analgesia for pleuritic pain
• if well hydrated and eGFR ≥30 mL/min, ibuprofen 400 mg oral 8-hrly
• in dehydrated patient or if eGFR <30 mL/min, to prevent renal damage, prefer morphine sulphate 10 mg oral 4-hrly - ibuprofen may be substituted once adequate fluid replacement achieved if eGFR ≥30 mL/min
• if patient pregnant, prefer morphine sulphate 10 mg oral 4-hrly
• if patient taking ACE inhibitor, avoid NSAIDS including ibuprofen 
• A high right atrial pressure (↑ JVP) is common and does not need to be treated
• AVOID diuretics
• Give intravenous fluids to restore perfusion see Fluid resuscitation guideline
• If it is felt that right heart catheter monitoring would be helpful, arrange to transfer patient to critical care

Pregnancy

• If a pregnant woman has collapse or shock associated with a haemodynamically unstable PE, discuss thrombolytic therapy with on-call obstetric consultant and haematologist
• 1-6% maternal bleeding complication rate, 1.7% fetal mortality, but no maternal mortality
• Nurse women in the second and third trimester on a left lateral tilt (never supine) or with manual displacement of the uterus to prevent aortocaval compression

Contraindications

[heading]Absolute

• Active bleeding

[heading]Relative

• Active pulmonary disease with cavitation
• Acute pancreatitis
• Aneurysm
• Aortic dissection
• Bacterial endocarditis
• Major trauma/major surgery within previous 4 weeks
• Stroke/TIA within previous 3 months
• Confirmed subarachnoid haemorrhage at any time
• Traumatic cardiac massage or intracardiac injection
• Known bleeding disorder
• Active dyspepsia or history of GI haemorrhage and/or oesophageal varices
• Sustained systolic BP ≥180 mmHg
• Proliferative retinopathy
• Recent head injury
• Pericarditis
• INR >2.0

Decision

• A consultant physician or SpR decides which carries most risk - possible complications of therapy, or embolism
• if thrombolysis contraindicated, go to THROMBOLYSIS CONTRAINDICATED below

Confirmed PE with haemodynamic instability

• Clinical features
• for ≥15 min either systolic blood pressure <90 mmHg or drops ≥40 mmHg from baseline
• hypotension that requires vasopressors or inotropic support
• clear evidence of shock
• Give alteplase 10 mg by IV injection over 1-2 min, followed by 90 mg by IV infusion over 2 hr (max 1.5 mg/kg in patients weighing <65 kg)
• if there is high risk of bleeding, use a half-dose regimen

Unconfirmed PE with haemodynamic instability

• If CTPA not available or is considered unsafe, before empiric administration of thrombolytic therapy, arrange urgent bedside echocardiogram to support a diagnosis of PE
• e.g. right ventricular enlargement/hypokinesis, or visualisation of clot
• If echocardiography is delayed or unavailable, discuss with consultant to consider empirical thrombolysis or to commence unfractionated heparin with loading bolus dose - see IV unfractionated heparin guideline

Thrombolysis unsuccessful

• Discuss with cardiothoracic surgery or interventional radiology
• emergency direct thrombolysis, catheter thrombo-embolectomy or pulmonary embolectomy, if available
• including requirements for peri-and post-operative anti-coagulation

Post-thrombolysis anti-coagulation

• Whether thrombolysis successful or unsuccessful, anti-coagulate as follows:
• after thrombolytic therapy has ceased, wait until APTT ratio has fallen below 2 before commencing or recommencing anticoagulation
• in all patients, start with unfractionated heparin with no loading bolus - see IV unfractionated heparin guideline
• remember need to monitor for Heparin Induced Thrombocytopaenia (HIT) - see HIT guideline

• Commence unfractionated heparin with loading bolus - see IV unfractionated heparin guideline
• Discuss with cardiothoracic surgery or interventional radiology
• emergency direct thrombolysis, catheter thrombo-embolectomy or pulmonary embolectomy, if available
• including requirements for peri-and post-operative anti-coagulation

Pregnant

• Monitor anti-Xa concentration as a guide to dosage adjustment
• Change unfractionated heparin to dalteparin when APTT stable - see Dalteparin for VTE guideline

Not pregnant

• Start warfarin or rivaroxaban. Follow PE: Haemodynamically stable guideline

• If not requiring thrombolysing or discussing with surgeon or interventional radiology, anticoagulate
• follow Pulmonary embolism: Haemodynamically stable guideline

• Follow Pulmonary embolism: Haemodynamically stable guideline