The care of critically ill patients requires a thorough understanding of pathophysiology and is centered initially on resuscitation of patients at extremes of physiologic deterioration. This resuscitation is often fast-paced and occurs early without a detailed awareness of the patients chronic medical problems. While physiologic stabilization is taking place, intensivists attempt to gather important background medical information to supplement the real-time assessment of the patients current physiologic conditions. Numerous tools are available to assist intensivists in the accurate assessment of pathophysiology and management to incipient organ failure, offering a window of opportunity for diagnosing and treating underlying disease(s) in a stabilized patient. Indeed, the use of invasive interventions such as mechanical ventilation and renal replacement therapy is commonplace in the intensive care unit. An appreciation of the risks and benefits of such aggressive and often invasive interventions is vital to assure an optimal patient outcome. Nonetheless, intensivists must recognize when patients chances for recovery are remote or impossible and counsel and comfort dying patients and their significant others. Critical care physicians often must redirect the goals of care from resuscitation and cure to comfort when the resolution of an underlying illness is not possible.
Assessment of Severity of Illness
Categorization of a patients illness into grades of severity occurs frequently in the intensive care unit (ICU). Numerous severity-of-illness (SOI) scoring systems have been developed and validated over the last two decades. Although these scoring systems have been validated as tools to assess populations of critically ill patients, their utility in predicting individual patient outcomes is not clear.
SOI scoring systems are important for defining populations of critically ill patients. This allows effective comparison of groups of patients enrolled in clinical trials. To be assured that a purported benefit of a therapy is real, investigators must be assured that different groups involved in a clinical trial have similar illness severities. SOI scores are also useful in guiding hospital administrative policies. Allocation of resources such as nursing and ancillary care can be directed by such scoring systems. SOI scoring systems also can assist in the assessment of quality of ICU care over time. Scoring system validations are based on the premise that increasing age, the presence of chronic medical illnesses, and increasingly severe derangements from normal physiology are associated with increased mortality rates. All currently existing SOI scoring systems are derived from patients who already have been admitted to the ICU. There are no established scoring systems available that purport to direct clinicians decision-making regarding criteria for admission to an ICU.
Currently, the most commonly utilized scoring systems are the APACHE (acute physiology and chronic health evaluation) system and the SAPS (simplified acute physiology score) system. These systems were designed to predict outcomes in critical illness and use common variables that include age; vital signs; assessments of respiratory, renal, and neurologic function; and an evaluation of chronic medical illnesses.
Apache II Scoring System