Comparison of non-invasive physiological assessment tools between simple and perforated appendicitis in children

PURPOSE The role of non-invasive measures of physiologic reserve, specifically the Compensatory reserve index (CRI) and the Shock index pediatric age-adjusted (SIPA), is unknown in the management of children with acute appendicitis. CRI is a first-in-class algorithm that uses pulse oximetry waveforms to continuously monitor central volume status loss. SIPA is a well-validated, but a discontinuous measure of shock that has been calibrated for children. METHODS Children with suspected acute appendicitis (2-17 years old) were prospectively enrolled at a single center from 2014 to 2015 and monitored with a CipherOx CRI™ M1 pulse oximeter. CRI values range from 1 (normovolemia) to 0 (life-threatening hypovolemia). SIPA is calculated by dividing heart rate by systolic blood pressure and categorized as normal or abnormal, based on age-specific cutoffs. Univariate and multivariable regression models were developed with simple versus perforated appendicitis as the outcome. RESULTS Almost half the patients (45/94, 48%) had perforated appendicitis. On univariate analysis, the median admission CRI value was significantly higher (0.60 versus 0.33, p < 0.001) and the ED SIPA values were significantly lower (0.90 versus 1.10, p = 0.002) in children with simple versus perforated appendicitis. In a multivariable model, only CRI significantly detected differences in the physiologic state between patients with simple and perforated appendicitis. CONCLUSIONS CRI is a non-invasive measure of physiologic reserve that may be used to accurately guide early management of children with acute simple versus perforated appendicitis.