Patient Safety Tip of the Week

January 4, 2011    Safer Use of PCA



Patient-controlled analgesia (PCA) has been a major development in pain management and, for the most part, has resulted in improved pain control and patient satisfaction, shorter lengths of stay, and better utilization of resources. Though having the theoretical  “built-in” advantage that should prevent inadvertent narcotic overdose (i.e. as the patient becomes drowsy, he/she cannot press the button to infuse more narcotic), use of PCA pumps have been associated with multiple problems of their own. PCA is another example where new technologies effectively eliminate some problems but introduce new problems of their own. Our May 12, 2009 Patient Safety Tip of the Week “Errors With PCA Pumps” dealt with a number of errors that may occur during use of patient controlled analgesia (PCA) and our April 27, 2010 Patient Safety Tip of the Week “Infusion Pump Safety” dealt with infusion pump issues in general. And we’ve discussed the issue of postoperative respiratory depression due to opioids in our Patient Safety Tips of the Week for July 13, 2010 “Postoperative Opioid-Induced Respiratory Depression” and September 21, 2010 “Dilaudid Dangers”.


ECRI  Institute in its Top 10 Health Technology Hazards for 2011 included oversedation during use of PCA infusion pumps as Number 7 on its list (see our January 2011 What’s New in the Patient Safety World column “ECRI’s Top 10 Health Technology Hazards for 2011”).


In 2006, in response to growing concerns about respiratory depression in patients on PCA, the APSF (Anesthesia Patient Safety Foundation) convened a workshop to address related issues (Weinger 2006). And in 2009 and 2010 the APSF again called for greater scrutiny of PCA (patient-controlled analgesia) in the postoperative period (Weinger 2009, Overdyk 2010).


The ECRI paper notes that the true prevalence of respiratory depression in patients on PCA is much higher than previously suspected since better monitoring has been implemented and may be as high as 41%. The ECRI recommendations are for monitoring not just vital signs but also mental status, pulse oximetry and capnography. They also discuss how to correctly assess the patients, use double checks for both orders and pump programming, and consider alternatives to PCA.


Very timely is an excellent article on a safety initiative to reduce PCA errors (Paul 2010). They reviewed over 25,000 patients treated with PCA at several Hamilton Acute Pain Service sites (McMaster University) over a 7-year period. Approximately half the patients used PCA before a comprehensive safety intervention was initiated and half after. They were able to demonstrate a significant reduction in PCA errors after the intervention (odds ratio 0.28). And PCA pump programming errors virtually disappeared after the intervention was implemented.


Their intervention included several key elements. First, they purchased new PCA pumps. These pumps had both “hard” stops and “soft” stops. Importantly, the user-interface for programming the pumps allowed visualization of all key parameters on one screen (the old pumps had required staff to scroll through 5 screens). By the way, the comment about displaying all the key parameters on one screen is a great human factors design concept that should apply not only to pumps but also to your CPOE systems. Any time a provider needs to scroll or click through multiple screens the chance for errors increases.


Second, they developed pre-printed order forms, designed to match the programming parameters on the new PCA pumps and including choices of three opioid preparations and their concentrations. The authors also note that CPOE is further likely to enhance the safety of prescribing PCA since it can provide feedback to the prescriber, such as alerts about dose range limits, etc. Standardized dosing of opioids is often not possible, given the wide variation in patient sensitivity to the effects of opioids. Nevertheless, well-designed preprinted order forms or CPOE entry screens can provide the options necessary for clinicians to prescribe PCA in most cases.


Third, the instituted a policy requiring independent double checks by nursing of the PCA settings incorporated into the orders. Fourth, they required nurses review all PCA program settings during each shift and on shift handovers.


Fifth, they instituted a rigorous program of education and training for nurses. Any nurse who will be responsible for care of patients with PCA’s must take a formal acute pain course with hands-on experience in pump programming. Lastly, they instituted a mandatory critical incident reporting program. And all these were in addition to the dedicated pain management service that they already had up and running for many years.


The article nicely summarizes the types and frequencies of the various sorts of errors associated with PCA. Overall (including both pre- and post-intervention cases), pump programming errors accounted for 33.9% of the PCA errors. 14.6% were caused by orders by non-pain-service providers, 12.9% by inadequate nurse education, 7.8% by PCA by proxy, and 1.6% by pump hardware failure. Over 77% of errors resulted in incorrect doses, most often an overdosing but occasionally underdosing. Most errors did not result in patient harm and none resulted in death. However, 34% of patients did have some harm, most often respiratory depression requiring oxygen or rescue with a narcotic antagonist (see also our Patient Safety Tip of the Week for July 13, 2010 “Postoperative Opioid-Induced Respiratory Depression” for a discussion of the phenomenon of renarcotization).


The summary of a 2006 workshop on postoperative respiratory depression sponsored by APSF (Weinger 2006) is well worth reading. Most participants felt that the same monitoring should be applied to all patients, noting that even low-risk patients occasionally develop respiratory failure while receiving opioids by PCA or neuraxial techniques. They also note that avoiding even one case of patient harm from respiratory depression could justify the cost of monitoring all patients. Thus a policy of “zero tolerance” for harm due to postoperative opioid-induced respiratory depression should be the goal. They all noted inadequacies of current monitoring systems but recommend at least pulse oximetry and continuous respiratory monitoring on all patients on PCA. They stressed that oxygen should not be used unless there is a specific indication since oxygen therapy may significantly delay recognition of respiratory depression.


Frank Overdyk (Overdyk 2010), a key participant in the 2006 APSF conference and long an advocate and researcher on respiratory depression from postoperative PCA, decries the fact that 3 years after the original APSF call for action very few hospitals have instituted continuous monitoring in PCA patients. He notes cases he has reviewed where monitoring intervals as far apart as every 4 hours have contributed to patient harm. He also stresses the false confidences that both nurses and physicians have in PCA. Nurses often think the lockout mechanism is foolproof. And physicians often think that respiratory depression only occurs in opioid-naďve patients, clearly a fallacy since it occurs in anyone on PCA.


We won’t reiterate here our prior discussion on pump programming errors or PCA by proxy. See our May 12, 2009 Patient Safety Tip of the Week “Errors With PCA Pumps” for those discussions and references to a whole host of great resources from ISMP (Institute for Safe Medication Practices).


So here is what your organization should be doing:


  • Consider moving to new PCA pumps that provide a better user programming interface and have “smart” safety features that help prevent administration of too much narcotic (but be very careful not to have different types of PCA pumps in use since the lack of standardization is likely to cause more confusion and errors).
  • Use preprinted order forms or standard order sets (for CPOE) for PCA ordering and include all the parameters needed to program the pumps.
  • Ensure that all staff (nurses, pharmacists, physicians, respiratory therapists) who will interact with PCA pumps are fully trained on the specific pumps they will be working with.
  • Be particularly careful that you do not have nurses who are not properly trained (eg. floaters, agency nurses, etc.) caring for patients on PCA.
  • Institute a policy for independent double checks for pump programming.
  • Include specifics of PCA pump use on your structured handoffs.
  • Have a system in place for monitoring patients physiologically continuously, including vital signs, level of arousal, pulse oximetry and capnography where available.
  • Make sure all staff understand how to properly assess ventilation in patients on opioids (by observing respiratory rate and depth when not stimulated) but all must understand that respiratory rate may not change early in respiratory depression and visualization is notoriously inept for identifying respiratory depression).
  • If you cannot perform capnography on all patients, try to ensure that you use it for monitoring high-risk patients (eg. those with known sleep apnea or a high STOP-BANG score, morbid obesity, COPD, significant chest wall deformities or certain neuromuscular diseases that impair ventilation, the elderly, and those with high ASA class).
  • In patients considered to be at high risk, consider monitoring postoperatively in higher levels of care (eg. ICU).
  • Do not administer oxygen unless there is a clearcut indication for doing so (since oxygen supplementation may delay recognition of significant respiratory depression). In those patients who must be on supplemental oxygen, consider whether they should have lower oxygen saturation targets.
  • Be aware of using other drugs that may suppress respiration (eg. sedating agents).
  • Have a monitoring/surveillance system in place to identify any errors related to PCA.
  • Do periodic audits of your PCA process (for all steps from ordering through administration and monitoring for both desired effects and unwanted effects).
  • Choose your patients carefully and ensure they understand all aspects of PCA. The ISMP monograph about patient safety issues involved in PCA published in 2006 (Cohen 2006) also discusses selecting appropriate patients for PCA and several other issues, including misprogramming PCA, monitoring patients, setting up quality indicators, and performing FMEA.
  • Make sure you also educate family and friends of patients (and nursing staff!) that PCA by proxy is not allowed.
  • Consider limiting the number of agents used with PCA (see our September 21, 2010 Patient Safety Tip of the Week “Dilaudid Dangers”).
  • Have protocols in place for how providers capable of appropriate response will be alerted if signs of respiratory depression occur (including whether a nurse may administer narcotic antagonists under “standing” orders)
  • Have protocols in place for each type of opioid analgesic that include how naloxone would be used to reverse respiratory depression.
  • Keep in mind that almost everything we have said may be applicable to the post-op patient receiving opioids via any route



PCA is a great therapeutic intervention that has lots of positives but it also has its downsides and risks that your must try to minimize. APSF has an upcoming Conference on Monitoring Postoperative Drug-Induced Respiratory Depression this June so expect to hear a lot more about progress in this area soon.







ECRI. ECRI Institute’s 2011 Top 10 Health Technology Hazards. Health Devices 2010; 39(11): 386-398



Weinger MB. Dangers of Postoperative Opioids. APSF Workshop and White Paper Address Prevention of Postoperative Respiratory Complications. APSF Newsletter 2006; 21: 61-67  Winter 2006-2007



Weinger MB, Stoelting RK. Special Editorial. Dangers of Postoperative Opioids—Is There A Cure? APSF Newsletter 2009; 24(2): 25-26  Summer 2009



Overdyk FJ. Postoperative Opioids Need System-Wide Overhaul (Letter to the Editor). APSF Newsletter 2010; 24(4): 61, Winter 2009-2010



Paul JE, Bertram B, Antoni K, et al. Impact of a Comprehensive Safety Initiative on Patient-controlled Analgesia Errors. Anesthesiology. 113(6): 1427-1432, December 2010


Cohen MR, Weber RJ, Moss J (Institute for Safe Medication Practices). Patient-Controlled Analgesia: Making it Safer for Patients. A continuing education program for pharmacists and nurses. ISMP. April 2006


Conference on Monitoring Postoperative Drug-Induced Respiratory Depression (June 08, 2011, Phoenix, AZ).

Essential Monitoring Strategies to Detect Clinically Significant Drug-Induced Respiratory Depression in the Postoperative Period

















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