Fat embolism

fat embolism-gurd criteria

major : (at least 1)

hypoxaemia

axillary or subconjunctival petechiae

CNS depression disproportionate to hypoxaemia

pulmonary edema

minor factors: (4 )

tachycardia >110

hyperthermia

sputum fat globules

retinal fat emboli

urinary fat

decreased platelets/haematocrit (unexplained)

increased ESR

reimplanted limb

(May-2007 Q14) An otherwise fit 30 yr old man is having microvascular reimplantation of his forearm. Describe methods available to optimise the perfusion of the perfusion of the reimplanted limb in the post-operative period.

Pharmacological and non pharmacological

Pharmacological :

1) regional anaesthesia induced sympatholysis and vasodilation of upper limb arterioles

2) dextran: polysaccharide, inhibits , promotes microvascular blood flow

Non pharmacological

1) keeping reimplanted limb warm

2) ensuring adequate hydration to avoid increased vasoconstriction and SVR

3) avoiding compartment syndrome, keeping replanted limb elevated

4) optimal Hb

5) appropriate monitoring of BP

6) monitoring of limb, early management of ischaemia

7) ?optimising venous pressure?

Although the question asked for management in the post operative period, no candidate was marked down for discussion involving intra-operative factors affecting post operative management.

Fat embolism syndrome

(May-2008 Q4) Describe the clinical features and treatment of Fat Embolism Syndrome.

Clinical features:
1) hemodynamic changes: tachycardia, hypotension, desaturation
2) ECG changes: right heart strain , RV failure
3) End tidal CO2 : marked reduction due to reduced preload and cardiac output
4) Clinical: confusion, dyspnea, petechiae

Treatment:
1) initial stabilisation, 100%O2, diuretics ventilatory support and endotracheal intubation if necessary
2) CVP, aspiration of embolus ??
3) Monitoring for complications eg ARDS, DIVC
4) Arterial blood gas and 12 lead ECG
5) early fracture fixation
6) controversial: heparinisation, corticosteroids


Marks for situations where FES is likely to occur

Diagnostic criteria (combined from various sources)
Diagnostic criteria were first devised by Gurd and have been modified several times since.8,9
Major criteria
• Respiratory insufficiency
• Cerebral involvement
• Petechial rash
Minor criteria
• Tachycardia
• Pyrexia (usually >39°C)
• Confusion
• Sustained pO2 <8 kPa • Sustained respiratory rate >35/minute, in spite of sedation
• Retinal changes - cotton wool exudates and small haemorrhages, occasionally fat globules seen in retinal vessels
• Jaundice
• Renal signs
• Thrombocytopenia
• Anaemia
• High ESR
• Fat macroglobulinemia
• Diffuse alveolar infiltrates 'snow storm appearance' on chest X-ray


Causes
• Fractures - closed fractures produce more emboli than open fractures. Long bones, pelvis and ribs cause more emboli. Sternum and clavicle furnish less. Multiple fractures produce more emboli
• Orthopaedic procedures - most commonly intramedullary nailing of the long bones, hip or knee replacements4
• Massive soft tissue injury
• Severe burns
• Bone marrow biopsy
• Nontraumatic settings occasionally lead to fat embolism. These include conditions associated with:
o Liposuction5
o Fatty liver
o Prolonged corticosteroid therapy
o Acute pancreatitis
o Osteomyelitis
o Conditions causing bone infarcts, especially sickle cell disease



Presentation
There is usually a latent period of 24 to 72 hours between injury and onset. The onset is then sudden, with:
• Breathlessness ± vague pains in the chest. Depending on severity this can progress to respiratory failure with tachypnoea, increasing breathlessness and hypoxia.
• Fever - often in excess of 38.3°C with a disproportionately high pulse rate.
• Petechial rash -commonly over the upper anterior part of the trunk, arm and neck, buccal mucosa and conjunctivae. The rash may be transient, disappearing after 24 hours.
• Central nervous system symptoms, varying from a mild headache to significant cerebral dysfunction (restlessness, disorientation, confusion, seizures, stupor or coma).
• Renal - oliguria, haematuria, anuria.
• Drowsiness with oliguria is almost pathognomonic.


Predictors of fat embolism
- long bone fractures (excluding NOF)
- multiple fractures