Patients in the PACU with a high risk for respiratory adverse events (RAEs) should be monitored for both noninvasive end-tidal carbon dioxide (CO2) and pulse oximetry using the Integrated Pulmonary Index (IPI), a new study suggests.
RAEs can lead to increased duration in the PACU and greater medical costs, or a transfer to the ICU due to airway narrowing, hypoxemia, wheezing and apnea, according to study author Hiroshi Morimatsu, MD, PhD, director, Anesthesiology and Resuscitology Department, Okayama University Hospital, in Japan. Pulse oximetry, which monitors oxygenation saturation (SpO2), is a commonly used method for monitoring respiratory failure. However, there is an increasing interest among clinicians in the functionality of measuring end-tidal CO2 after intubation, which is currently not done in the postoperative setting, according to researchers.
“We normally do only SpO2 in the PACU patients,” said Dr. Morimatsu. “Even in the PACU … and in daily practice, we don’t measure the end-tidal CO2.”
The IPI is a 10-point scale developed by Medtronic that combines a patient’s end-tidal CO2, pulse oximetry, respiratory rate and pulse rate (10 is good; 1 represents a dangerous and serious complication). The IPI is taken as soon as a patient enters the PACU. Dr. Morimatsu and his colleagues conducted a retrospective observational study to test the efficacy of the IPI for predicting RAEs in the PACU.
The study included 163 patients with a high risk for hypoventilation in the PACU after general surgery. Patients were considered high risk if they were older than 75 years of age or had a body mass index greater than 28 kg/m2. The patients were enrolled at two centers from October 2014 to February 2015.
There were 11 patients (7%) who suffered an RAE; one patient required operation and treatment in the ICU. Dr. Morimatsu noted that this finding is similar to other studies in the medical literature. The PACU stay for patients with an RAE was almost double the time of patients without an RAE (97.2 ± 44.4 vs. 51.8 ± 27.2 minutes; P<0.0001). The researchers also found lower initial IPI and SpO2 measurements for the RAE group compared with the non-RAE group (6.5 ± 2.5 vs. 9.1 ± 1.3; P<0.0001 and 96.6% ± 4.4% vs. 98.3% ± 1.9%; P=0.0147, respectively).
The researchers concluded that IPI has better sensitivity and specificity, making it superior to pulse oximetry alone for predicting the onset of RAE after surgery. “SpO2 can give you the oxygenation—if it’s good or not—but we cannot assess the respiration,” Dr. Morimatsu said. “IPI can give us a number, and this number is very easy to understand: 10 is OK; 1 is very bad.”
Dr. Morimatsu said there are currently no set guidelines for the IPI scores. He suggested that clinicians should pay more attention to any patient who scores less than 7. He said more research is needed, and he is looking to conduct a larger multicenter study that will look at other types of patients.
The findings were presented at the 2015 annual meeting of the American Society of Anesthesiologists (abstract A3024).