The germs enter an individual’s system and then cause tissue or organ damage. Severe sepsis depends on how an organ dysfunction is attributed, such as an underlying infection. The provision of supportive therapy, such as mechanical ventilation, defines organ dysfunction. In the United States, severe sepsis occurs in about 2% of patients admitted to the hospital. Of this 2%, about half are treated in the intensive care unit, making up about 10% of ICU patients. Studies show that nearly 50% of patients who experience sepsis are likely to have acute lung injury. Providing mechanical ventilation to these patients allows the respiratory system to rest so that the body’s energy can be used for treating the infection. (Sevransky, 2004)
Severe sepsis can occur from both healthcare-associated and community-acquired infections. However, about half severe sepsis cases are caused by pneumonia, followed by intraabdominal and urinary tract infections. Blood cultures are negative about one-third of the cases and positive another third. Escherichia coli, klebsiella species, and Pseudomonas aeruginosa predominate gram-negative isolates, whereas Staphylococcus aureus and Streptococcus pneumoniae are the most common gram-positive isolates. (Ranieri,