Scoring of severity in patients admitted to a respiratory intensive care unit

A number of attempts have been made to develop measures of severity of illness for patients in the intensive care unit (ICU), but the impact of these indices in a Respiratory Intensive Care Unit (RICU) has not really been studied. At present, outcome can be accurately predicted in approximately 85% of ICU patients, while no data are available for the RICU. These indices will be reviewed in the article. The sophisticated Mortality Probability Model (MPM) II is used to predict the outcome of ICU patients. This technique is based on statistically-derived weights for its variables. The "most popular" indices are the Acute Physiology and Chronic Health Education (APACHE), the Simplified Acute Physiological Score (SAPS) and the Therapeutic Intervention Scoring System (TISS). Overall, the predictive accuracy of the latest APACHE III equation and score is rather good, but there are important limitations concerning its use in the RICU. The SAPS includes 17 variables, and can be considered as a simplified version of APACHE sharing with it the same problems of application. The TISS requires data on approximately 70 treatment variables and assigns each a score ranging 1-4. A high score represents serious intervention, while a low score illness requires much less medical or nursing intervention. The sum of these scores indicates severity of illness because more critical patients are presumed to require higher levels of interventions. The RICU is also characterized by the use of noninvasive mechanical ventilation (NMV) in the treatment of acute respiratory failure. Some indices able to predict the success of NMV, have been developed recently during a brief trial of NMV, and included the level of acidosis and hypercapnia.