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October 26, 2015
11:00:00 AM - 12:30:00 PM
Room Upper 10
Integrated Pulmonary Index Can Predict Respiratory Adverse Events in Postoperative High-Risk Hypoventilation Patients at Post-Anesthesia Care Unit
Shuji Okahara, M.D., Kenzo Ishii, M.D., Hiroshi Morimatsu, M.D.,Ph.D.
Okayama University Hospital, Okayama, Japan
Disclosures: S. Okahara: None. K. Ishii: None. H. Morimatsu: None.

The integrated pulmonary index (IPI) is the respiratory parameter derived from 4 parameters including noninvasive end-tidal CO2, respiratory rate, pulse rate and SpO2. Recently many clinicians focus on utility of measuring end-tidal CO2 after extubation. However, usefulness of the IPI is not validated in postoperative settings yet. We assessed the efficacy of measuring IPI in postoperative patients with high risk of hypoventilation at post-anesthesia care unit (PACU).


In this prospective observational study, we defined obese patients (a body-mass index of more than 28) or geriatric patients (more than 75 year-old) as postoperative patients with high risk of hypoventilation. These patients at our PACUs after general surgery were enrolled at 2 centers from October 2014 to February 2015. As usual, they were monitored with ECG, pulse oximeter, blood pressure and respiratory rate in both PACUs. Additionally, we monitored noninvasive end-tidal CO2 from nasal prong with Capnostream 20. We investigated onset of respiratory adverse events (RAE) defined as following; respiratory event with prolonged stay in PACUs or transfer to intensive care units, because of airway narrowing, hypoxemia, hypercapnia, wheezing and apnea. We compared variables with either Student’s t test or χ² test, and P value <0.05 was considered statistically significant.


Of the 162 patients, eleven patients (7%) suffered from RAE. Among them, one patient needed re-operation and treatment in intensive care unit. The duration of PACUs was longer in patients with RAE than in those without RAE (RAE group: 97.2 ± 44.4 minutes vs. non-RAE group: 51.8 ± 27.2 minutes; p < 0.0001). Initial IPI of RAE group was lower than that of non-RAE group (6.5 ± 2.5 vs. 9.1 ± 1.3; p < 0.0001). Similarly, Initial SpO2 of RAE group was lower than that of non-RAE group (96.6 ± 4.4% vs. 98.3 ± 1.9%; p =0.0147). We finally found that sensitivity and specificity of IPI were better than that of SpO2 for onset of RAE. The area under the receiver operating characteristic (ROC) curve of IPI was 0.86 and that of SpO2 was 0.56.


After general surgery, the incidence of RAE was 7% for postoperative patients with high risk of hypoventilation at PACU. IPI on admission to PACU can predict onset of RAE better than SpO2 alone. This result suggests the necessity to measure noninvasive end-tidal CO2 in addition to pulse oximetry at high-risk patients in a PACU.

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