Patient Safety Tip of the Week


February 21, 2012

Improving PCA Safety with Capnography



We’ve stressed on numerous occasions the difficulties monitoring patients on PCA pumps or receiving postoperative opioids by other routes. The primary danger is development of respiratory failure. Some patients may be at greater risk because of concomitant conditions (eg. obstructive sleep apnea, massive obesity, COPD, various neuromuscular disorders) or because of concomitant medications (benzodiazepines or other sedating agents).


Use of pulse oximetry to monitor such patients can give rise to a false sense of security (see our December 6, 2011 Patient Safety Tip of the Week “Why You Need to Beware of Oxygen Therapy”). Patients with respiratory depression secondary to opioids or sedatives typically develop CO2 retention well before they develop oxygen desaturation. So a good monitoring strategy would utilize capnography.


One organization recently shared its experience with adoption of capnography for all patients on PCA pumps (Maddox 2012). They use the capnography apparatus to monitor both the respiratory rate and the end-tidal CO2.


Their initial experience led to adjustment of their monitoring parameters. They started with alerts programmed for respiratory rates of 10 or less or “no breath” for 30 seconds and an end-tidal CO2 level of 50. However, they found too many “nuisance” alarms at those levels so reprogrammed their alert targets to respiratory rates of 6 and end-tidal CO2 to 60.


The article nicely describes all the steps they went through to plan and implement the system and the daily mechanics involved. Since 2004 they have used the system for virtually all patients on PCA and have also begun using it on patients receiving epidural PCA or opioids via other routes. In over 5000 patients they have had no serious respiratory complications of PCA. They also calculated an estimated ROI (based on potentially avoided intubations, transfers to ICU, etc.) and felt that the 5-year ROI was about $2.5 million for their organization. Plus all the ROI in human terms! Pretty impressive!


They do note that patient mobility is limited when hooked up to the pumps and capnography equipment. However, they also note that most patients who are mobile no longer have the need for the PCA pumps.


Continuous capnography may not be the complete answer to patient safety in patients on PCA. Note that several times we have quoted the excellent article by Lynn and Curry (Lynn 2011) that discussed several mechanisms for unexpected deaths in hospitalized patients (see our February 22, 2011 Patient Safety Tip of the Week “Rethinking Alarms”). That article nicely outlines the multiple problems involved in developing the ideal monitoring system. Our September 6, 2011 Patient Safety Tip of the Week “More Tips on PCA Safety” also noted a unique “apnea prevention device” (Zornow 2011) that uses inputs from multiple modalities to create a system for alerting providers to impending respiratory disasters.


We also came across some excellent informal discussions on PCA safety through the Becker’s ASC Review website ( One was an interview with Bryanne Patail of the VA’s National Center for Patient Safety (Wong 2012) who noted that more than 50 percent of these events events related to infusion pumps, suggesting that incidents with PCA pumps are about 10 times more frequent than with general-purpose pumps. That, of course, reflects that occurrence of respiratory depression related to the opioid infusions. The VA has also reduced its PCA events by integrating capnography into its PCA systems. The second was about the Physician-Patient Alliance for Health & Safety (PPAHS) putting together a working group to create a checklist targeted towards PCA (Kurtz 2011). It has interviews with multiple healthcare providers who have excellent suggestions for items to be included on such a checklist. On the Physician-Patient Alliance for Health & Safety website are some heart-wrenching stories about patients who died during PCA, likely as a result of inadequate monitoring. We look forward to seeing that checklist when it is ready.



In our May 17, 2011 Patient Safety Tip of the Week “Opioid-Induced Respiratory Depression – Again!” we encouraged hospitals to perform their own FMEA (Failure Mode and Effects Analysis) on the PCA process and provided links to two tools we use when doing FMEA’s of the PCA pump process: the PCA Pump Audit Tool and the PCA Pump Criteria.  And we hope that you’ll go back and look at the string of recommendations we made in our September 6, 2011 Patient Safety Tip of the Week “More Tips on PCA Safety”. We think you will find them extremely helpful.



Understanding the complexities of respiration as it relates not only to various medications but also to underlying patient conditions is extremely important in managing the postoperative patient. Implementing a PCA safety program is one of the most important things your organization can do to improve the perioperative care of patients and avoid unnecessary morbidity and mortality.




Prior Patient Safety Tips of the Week pertaining to opioid-induced respiratory depression and PCA safety:




Prior columns pertaining to oxygen safety:


·        April 8, 2008 Patient Safety Tip of the Week “Oxygen as a Medication

·        June 10, 2008 Patient Safety Tip of the Week “Monitoring the Postoperative COPD Patient

·        January 27, 2009 Patient Safety Tip of the Week “Oxygen Therapy: Everything You Wanted to Know and More!

·        April 2009 What’s New in the Patient Safety World column “Nursing Companion to the BTS Oxygen Therapy Guidelines”.






Maddox RR, Williams CK. Clinical Experience with Capnography Monitoring for PCA Patients. APSF Newsletter 2012; 26(3: 47-50 Winter 2012



Lynn LA, Curry JP. Patterns of unexpected in-hospital deaths: a root cause analysis. Patient Safety in Surgery 2011, 5:3 (11 February 2011)



Zornow MH. Clinical Testing of the Apnea Prevention Device: Proof of Concept Data. Anesth Analg 2011; 112:;582-586



Wong M. Reducing Errors With Patient-Controlled Analgesia Pumps: Q&A With Bryanne Patail of the National Center for Patient Safety. Physician-Patient Alliance for Health & Safety. February 09, 2012



Kurtz R. How to Prevent 'Dead-in-Bed' Syndrome With Patients After Surgery: Q&A With Physician Experts & PPAHS. November 09, 2011



Physician-Patient Alliance for Health & Safety

















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