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Abstract

Learning Objectives: Many currently available scoring systems characterizing physiological disturbance in critical illness ignore or only partially allow for the level of physiological support. For example, a patient may have a “normal” blood pressure while on inotropes or vasopressors. Hypothesis: A score of instability weighted for the degree of support could be developed from ranges used in current scoring systems and physiological principles. Methods: Five key consistently recorded physiological parameters were used to develop the score. These were mean arterial blood pressure, heart rate, oxygen saturation, urine output and body temperature. They were divided into 7 ranges of derangement. A literature review of other scores and accepted physiological limitations in adults informed decisions about the upper and lower limit each parameter was assigned within a particular range. A value for a parameter falling within the normal range scored zero points and up to 3 points for increasing derangement. Mean arterial pressure and oxygen saturation which can be substantially affected (positively or negatively) by pharmacological or physiological intervention were weighted accordingly. Mean arterial pressure was weighted for quantities of inotropes, vasopressors, fluids and sedation. Oxygen saturation was weighted for inspired oxygen fraction and positive end expiratory pressure. Up to 6 points could be added or subtracted according to the parameter and the weighting factor. An iterative and incremental development approach was used to repeatedly refine the scoring system against a series of virtual clinical scenarios to ensure that changes in individual parameters led to appropriate adjustment of the score. Results: Repeated iterations of the scenarios resulted in the final version of the 51 point score. This score was then calculated repeatedly using real datasets and graphical outputs displayed. Conclusions: This new quantitative score may have clinical utility because of the ability to reflect alterations in underlying physiology which may be masked by increasing levels of support.