Adding O2, CO2 monitors to PCA improves patient safety

"The most serious adverse event associated with opioid analgesics is respiratory depression due to overmedication," said Ray Maddox, Pharm.D., director of clinical pharmacy services and research and pulmonary medicine at St. Joseph's/ Candler Health System (SJCHS) in Savannah, Ga. "Integration of PCA technology with technology that automatically measures and reports SpO₂ and ETCO₂ levels provides immediate notification of when respiratory rates fall dangerously low."

SJCHS was the first to utilize this improved patient safety platform. Working with Cardinal Health in San Diego, Calif., Maddox and his colleagues integrated the PCA technology of the Alaris System sold by Alaris Medical Systems, a Cardinal subsidiary, with the OxiMax product sold by Nellcor Puritan Bennett in Pleasanton, Calif., which monitors SpO₂, and the Microstream product of Oridion in Needham, Mass., which monitors ETCO₂.

According to Maddox, patients on PCA are typically monitored by intermittent assessments, reflecting cognition, nausea, blood pressure, respiratory rate, level of sedation, intermittent use of pulse oximetry, and review of PCA dosing history and pain scores. Assessments may be conducted hourly for the first several hours after initiating PCA therapy, but they are usually conducted only once every few hours after that. "Especially during the first 24 hours and at night, when nocturnal hypoxia can occur, clinicians may not monitor a patient often enough," he said. And nursing shortages may increase the danger that overmedication may be undetected, he noted.

In addition, "an intermittent assessment can stimulate an oversedated patient to a higher level of consciousness and increased respiratory rate. Once the stimulus is removed, a patient can return to an oversedated state," Maddox said.

Because changes in respiratory status are a leading indicator of adverse patient response to opioid infusion, an automated integrated PCA-respiratory monitoring system is "invaluable to patient safety," said Maddox. It provides what Cardinal officials describe as "a concise, time-stamped review of dosage information alongside monitoring values."

Both the infusion and monitoring modules have a hospital-defined set of dosage limits in the infusion-system computer to protect patients from medication errors. In addition, when paired with the PCA, the ETCO₂ module provides up to 24 hours of combined data on trends to aid in assessment and delivery of pain management.

Adventist Medical Center in Portland, Ore., integrated the PCA module with the SpO₂ enhancement in mid-2005. "The result has been significantly fewer codes from PCA-related problems," said Cliff Edwards, R.Ph., staff pharmacist at Adventist, adding that the integrated system has the additional value of data collection. "The combined platform also allows us to collect dosage data, which leads to more precise analgesic dosing," he said.

Maddox said that the SJCHS experience has provided several important lessons: