CURRENT Essentials of Critical Care.pdf

90 Current Essentials of Critical Care■■■Pulmonary ThromboembolismEssentials of Diagnosis• Dyspnea, tachypnea, tachycardia, pleuritic chest pain; calf painand swelling consistent with deep vein thrombosis (DVT)• Hypotension, syncope, cyanosis, shock if “massive” (50% pulmonaryvascular bed occlusion); or submassive in patient withpoor cardiopulmonary reserve• Mild to moderate hypoxemia, increased P(A-a)O 2 , mildly reducedPaCO 2• Sinus tachycardia most frequent ECG abnormality; “S1Q3T3”pattern of right heart strain considered highly predictive but seenin 12% of patients with pulmonary embolism (PE)• D-dimer, fibrin degradation product in patients with DVT andPE usually 500 g/dL• Normal chest radiograph in hypoxemic individual should leadto suspicion of PE; other common radiographic findings includeplatelike atelectasis, small pleural effusions• Diagnostic imaging techniques include Doppler ultrasound ofsymptomatic extremity, radionuclide ventilation-perfusion scan,helical (spiral) CT angiogram, pulmonary angiogram• Risk factors: immobilization, trauma to extremity, previousDVT/PE, recent surgery, obesity, nephrotic syndrome, congestiveheart failure, stroke, malignancy, estrogen useDifferential Diagnosis• Acute coronary syndrome • Fat embolism• Acute chest syndrome • Asthma• Spontaneous pneumothoraxTreatment• Prevention in ICU patients with risk factors is paramount• If no contraindications, once DVT or PE suspected, anticoagulationwith unfractionated or low-molecular-weight heparin shouldbe instituted while awaiting confirmatory diagnostic testing• Thrombolytic therapy may be option in patients with “massivePE”; may consider in patients with hypotension to hasten hemodynamicstabilization■ PearlVentilation-perfusion scans in patients with COPD are generally consideredto be of limited value because airway obstruction can causea falsely positive perfusion defect due to hypoxemic mediated vasoconstriction.ReferenceRocha AT, et al: Venous thromboembolism in intensive care patients. ClinChest Med 2003;24:103. [PMID: 12685059]