Sunday, November 11, 2007

Treatment of pulmonary embolism in critical illness

A very helpful review appeared recently in Chest. Key points follow:

Get a bigger bang for the buck with CT by measuring RV and LV diameters. RV/LV diameter ratios over 0.9 are concerning for right ventricular dysfunction.

Echocardiography is useful in the assessment of RV function.

Biomarkers (troponin, BNP, ProBNP) are potentially useful indicators of RV damage and wall stress. Given the shorter half life of BNP and ProBNP these markers are more useful than troponin for assessment of patient progress in real time. Q 12 hour determinations are suggested by the authors.

Assessment of RV function by any means is useful for assessing risk. Negative predictive power exceeds positive predictive power.

Hemodynamic support
Judicious volume infusion can improve RV function. Theoretical adverse effects of RV over distension are cited.

Norepinephrine is favored for vasopressor support. However, this is based largely on animal data. High level comparative clinical studies are not available.

Antithrombotic and antiembolic strategies
Intravenous anticoagulants are favored over subcutaneously administered anticoagulants if the patient is critically ill.

Concerning contraindications the authors state: Only rarely is anticoagulant treatment flatly contraindicated (eg, active hemorrhage in the brain or another vital organ, uncontrolled bleeding threatening tissue perfusion); but in those situations, consideration of prompt placement of a vena cava filter (see below) and clot removal (see above) should be undertaken.

The established indication for intravenous thrombolytic therapy is PE causing shock. Potential indications are deterioration despite standard treatment and normotensive patients with RV dysfunction.

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