An evaluation of the Integrated Pulmonary Index (IPI) for the detection of respiratory events in sedated patients undergoing colonoscopy

The Integrated Pulmonary Index (IPI™) is a new decision making tool calculated from measured end tidal carbon dioxide (etCO₂), respiratory rate (RR), oxygen saturation (SpO₂) and pulse rate (PR) using a fuzzy logic model. The aim of this study was to compare prospectively IPI to respiratory adverse events in patients undergoing moderate sedation for colonoscopy. Following ethics committee approval and personal informed consent 51 adult patients undergoing elective colonoscopy were enrolled. Patients received routine care by the endoscopy staff that were blinded to IPI, etCO₂, and RR; whilst a trained senior anesthesiologist observer, not involved in the procedure, collected this data. ‘Requires attention’ respiratory adverse events (at least 1 min of SpO₂ ≤ 92 % and/or RR ≤ 8 and or 20 % decrease in etCO₂) and ‘requires intervention’ respiratory adverse events (at least 1 min of SpO₂ ≤ 85 % and/or RR = 0) were documented by the observer. There were no differences in etCO₂, RR, SpO₂ and PR between 5778 IPI readings ranging from 1 to 10. Low (1–3), medium (4–6) and high (7–10) IPI groups did not differ in RR, SpO₂ and PR, but etCO₂ was higher in the high IPI group (p = 0.0185). Among requires attention events (n = 113) the IPI was high (7–10) in 53.1 %, intermediate (4–6) in 32.7 %, or low (1–3) in 14.2 %. The presented data demonstrate limited agreement between respiratory physiological parameters and the IPI. Further IPI evaluation and validation is indicated mainly for events requiring immediate intervention and in different patient populations including obese patients.