The clinical diagnosis of pulmonary emboli is unreliable, being both insensitive and nonspecific. Many cases are clinically silent with only 30% having the clinical features of a DVT and only 70% demonstrating a DVT on venography. Individuals with a massive pulmonary embolus, who are compromised for more than 60% of pulmonary circulation, are considered critically ill. Right heart failure may progress to cardiovascular collapse with hypertension, coma and death. A sub-massive pulmonary embolus presents with tachycardia, tachypnea and signs of pulmonary infarction with consolidation, rales, hemoptysis, pleuritic chest pain, pleural friction rub, pleural effusion and fever. In most cases individuals often present with a few nonspecific clinical findings and the major clinical complaints of malaise and fever.