Page 88 - Critical Care Notes

4223_Tab02_045-106 29/08/14 10:00 AM Page 82

CV

Pathophysiology
Causes: accidents, stab wounds, gunshot wounds, rupture of tumors, obstruc-
tion of lymphatic or venous flow, pericardial effusion → accumulate blood in
the pericardial sac → ↑ venous pressure → compress all four chambers of the
heart → RA and RV are compressed →↓ RA filling during diastole →↓ venous
blood returns to RA → ↑ venous pressure → JVD, edema, hepatomegaly, ↑ DBP
→ continued compression of the heart →↓ diastolic filling of ventricles →↓ SV,
↓ CO, ↓ tissue perfusion → body attempts to increase blood volume, increase
SV ↑→ workload of the heart → body compensation → tachycardia → all these
complications last for a limited amount of time → shock, cardiac arrest, or death
if not immediately corrected.
Clinical Manifestations
First Signs
■ Anxiety and restlessness, syncope
■ SOB, dyspnea on exertion, orthopnea, cough
■ Unwillingness to lie flat
■ Cool, diaphoretic skin
■ Sense of impending doom
Classic Signs
■ Beck’s triad: muffled heart sounds, increased JVD, and hypotension
■ Narrow pulse pressure (↓ SBP and ↑ DBP)
■ Hemodynamics: ↑ CVP >20 mm Hg, ↑ PCWP, ↓ CO
■ Tachycardia
■ Weak, thready pulse
Late Signs
■ Pulsus paradoxus (↓ SBP of more than 10 mm Hg on inspiration)
■ Electrical alternans (alternating levels of voltage in P waves and QRS
complexes in all leads and possibly in T waves)
Diagnostic Tests
■ Chest x-ray
■ Echocardiogram
■ ECG
■ CT, MRI

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