Horowitz index

The Horowitz index was first proposed in a 1974 paper by Joel H. Horovitz and two co-authors, Charles Carrico and G. Tom Shires. The reason for the spelling with w is unclear. In this study, the authors utilized the PaO2/FiO2 ratio to compare patients treated with varying inspired oxygen concentrations. One of the major reasons for the use of this ratio is that it is simple to calculate in critically ill patients. These patients often have arterial blood gas samples taken, which allows providers to measure the PaO2. == Uses ==

The Horowitz ratio has used in scoring systems to grade severity in diseases such as acute respiratory distress syndrome (ARDS), sepsis, and community-acquired pneumonia. ARDS The Horowitz index plays a major role in the diagnosis of ARDS. Three severities of ARDS are categorized based on the degree of hypoxemia using the Horowitz index, according to the Berlin definition. The Horowitz index also correlates to mortality in ARDS. • Table adapted from Ranieri et al. Sepsis The Horowitz index is used in multiple severity scoring systems in sepsis. These include the SOFA, APACHE IV, SAPS-II and SAPS-III scoring systems. Community-Acquired Pneumonia In patients with community-acquired pneumonia, the Horowitz index is used in the SMART-COP score. This score predicts the need for additional respiratory support in community-acquired pneumonia. This score can help medical providers determine a patient's need for admission to an intensive care unit (ICU) or further intensive respiratory support or vasopressor medications. Further support or admission to the ICU should be considered in patients 50 years old with Horowitz index <250 mmHg. ==See also==