Fat / Pulmonary Embolus (PE)

Embolus

Abnormal mass of undissolved material that is carried in the bloodstream from one place to another

Components of Emboli

Thrombi or mixtures of thrombi and clot
Fat: long bones,
Atheroma - rupture of aotic plaques with emboli to mesenteric vessels
Tumour cells
Air: cannulae, open neck veins, dialysis
Nitrogen: Caisson's disease
Amniotic fluid: labour
Infective: IE
Foreign material - plastic tubing from broken cannulae

	Pulmonary Embolus	Fat Embolism Syndrome
Trigger/PDF	Wall Increased ageing Vessel injury (limb injury) Flow (prolonged stasis) Prolonged bed rest Recent surgery Cardiac failure Constituents Polycythemia Malignancy Dehydration Coagulopathy - ProteinC/S, ATIII deficiency, Factor V Leiden, Antiphospholipid antibodies, HRT, OCP	Local trauma Trauma / long bone fractures Joint reconstruction Systemic Major burns cardiopulmonary bypass Diabetes Pancreatitis
Pathophysiology	Thrombi form in deep veins / right atrium Propagate Obstruct pulmonary artery (beyond right ventricular outflow tract) Produces right ventricular strain Reduced blood flow to lung produces V/Q mismatch (and increased physiological dead space)	Mechanical theory Damaged vasculature releases fat droplets into circulation Enter pulmonary vascular bed Enter systemic circulation via arterio-venous shunts Impaction of emboli in terminal systemic vascular beds produces local ischaemia and tissue injury Biochemical theory Stress hormones released (steroids, catecholamines) Activate lipases Lipases hydrolyse circulating lipids into FFAs and glycerol FFAs induce pulmonary damage and increase capillary permeability
Clinical features	Local Painless/painful swelling or tenderness of calf Phlegmasia cerulea dolens - ischaemic cyanotic leg following massive ileo-femoral venous thrombosis Phlegmasia alba dolens - ischaemic cyanotic leg following massive ileo-femoral DVT with arterial spasm Distal Pulmonary embolism Tachycardia, tachypnoea Pleuritic chest pain Shock (outflow obstruction) Right ventricular strain Paradoxial embolisation (through PFO) leading to systemic embolisation	Respiratory insufficiency Tachypnoea, cyanosis - pulmonary vascular occlusion by lipid emboli Petechial rash Distributed in area of chest, mouth, axilla, conjunctiva - direct embolisation of cutaneous vessels Cerebral features Encepalopathy / distinct peripheral weakness - microvessel embolisation Pyrexia, tachycardia, retinopathy, renal impairment
Management	Prevent Early mobilisation Heparin TED stockings Intermittent pneumatic compression (intraoperatively) Transvenous intracaval device - umbrella + wire filters Treat Resuscitate Investigate ABG - V/Q mismatch Plasma D-dimers FDP from action of plasmin on fibrin clot Measured by latex agglutin test Misses 10% of PEs ECG Sinus Tachycardia S₁Q₃T₃ CXR - exclude differentials VQ scan Spiral CT Pulmonary angiography Specific therapy Thrombolysis - Haemodynamically unstable Pulmonary embolectomy Anticoagulation: Heparin + warfarin	Investigations ABG FBC Clotting Electrolytes Urine: Lipiduria CXR: "snow storm" appearance ECG: Tachycardia and RV strain Respiratory support - Oxygenation, CPAP Fluid/electrolyte balance General: DVT prophylaxis, nutritional support

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