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Opioid-induced respiratory depression (OIRD) is a significant issue in hospital inpatients, as well as in post-anesthesia care patients. Many of our initial columns on OIRD focused on post-surgical patients. But in our January 2020 What's New in the Patient Safety World column Opioids and Apnea: Not Just Surgical Patients we pointed out that over half of non-surgical inpatients receive opioids, often in high doses. And high percentages of both medical and surgical patients have undiagnosed obstructive sleep apnea (OSA) that is a major risk factor for OIRD.
Our many columns on OIRD have emphasized several key elements to consider in order to avoid OIRD:
Patient selection includes both asking whether use of opioids is necessary and assessment for risk factors for OIRD. Foremost is assessment for possible obstructive sleep apnea (OSA), using a tool such as the STOP-BANG questionnaire. But you also need to consider whether there are other medical comorbidities (eg. COPD) that might predispose to OIRD and whether the patient is also receiving other medications that might depress respiration.
Once you have determined that an opioid is necessary, you need to decide which one to use and proper dosing. That includes determination as to whether the patient is opioid naοve or opioid tolerant. We recommend that you avoid providing too many choices for specific opioids, since issues of equipotency always come into play. In particular, we recommend avoiding HYDROmorphone (Dilaudid) because clinicians often underestimate the potency on a milligram basis (see our multiple columns on Dilaudid dangers listed below). We encourage standardization on a few products and incorporation of those into standardized order sets. And, if you are going to use PCA (patient-controlled analgesia), we recommend you use our PCA Pump Audit Tool and PCA Pump Criteria tools or the PCA Safety Checklist put out by the Physician-Patient Alliance for Health & Safety (PPAHS 2012).
Proper monitoring is essential. Monitoring end-tidal carbon dioxide (ETCO2) by capnography is now the accepted gold standard. Wed like to see every patient on opioids monitored with capnography. Realistically, some hospitals may not have the resources to use capnography on all patients receiving opioids. But clearly those at high risk for OIRD should be on capnography. Monitoring with only pulse oximetry is inadequate and often leads to a false sense of security. Hypoxemia occurs relatively late in opioid-induced respiratory depression. Much earlier, pCO2 begins to rise and leads to obtundation and eventually respiratory arrest. Patients usually dont become hypoxemic until substantial reduction in respiration has occurred. Hence, the need for monitoring for hypercapnia by using continuous capnography to monitor end-tidal carbon dioxide (ETCO2).
One hospital recently published its results from implementation of a comprehensive program aimed at avoiding OIRD incidents (Steele 2020). A midwest medical center found that it continued to experience frequent opioid-related adverse events despite introduction of some interventions intended to reduce them. Most of those consisted primarily of educational interventions (aimed at both clinicians and patient/families) but weve pointed out so many times that educational interventions are in the lowest tier of effectiveness for any interventions. So, they introduced a number of measures, including staff education, sleep apnea risk assessment documentation and communication, revisions to PCA policies and procedures, and revisions to preprinted PCA orders. In addition, a smart infusion pump system with continuous capnography to monitor end-tidal carbon dioxide (ETCO2) was introduced for use with all PCA patients, epidural patients, and patients considered at high risk of respiratory depression. (Prior to 2010, monitoring of at-risk patients receiving opioids had been done primarily by pulse oximetry.) The smart infusion pump system incorporated a PCA pause functionality automatically stopping opioid delivery to those patients who are identified as compromised.
They measured opioid-related adverse reactions (ADRs) before and after those interventions. Compared with the pre-implementation period, the post-implementation period the number of severe adverse reactions dropped from 3.08 to 0.64 per 10,000 patients treated with opioid, a statistically significant 79.2% reduction. The relative proportion of code blue events decreased from approximately 40% before the introduction of capnography monitoring to just more than 10% per year after introduction, to nearly 0% by the end of the study period. Moreover, there was also a reduction in the duration of opioid treatment (average 2.05 vs 1.37 days).
Rates of mild and moderate ADRs actually increased in the post-capnography period, but that should not be surprising. The addition of capnography monitoring likely led to earlier recognition of respiratory depression and intervention before serious respiratory depression had occurred.
This is a good example of how a multi-pronged plan can be successfully implemented and deliver the outcomes desired.
Other Patient Safety Tips of the Week pertaining to opioid-induced respiratory depression and PCA safety:
Our prior columns on patient safety issues related to Dilaudid/HYDROmorphone:
PPAHS (Physician-Patient Alliance for Health & Safety). PCA Safety Checklist.
Steele T, Eidem L, Bond J. Impact of Adoption of Smart Pump System With Continuous Capnography Monitoring on Opioid-Related Adverse Event Rates: Experience From a Tertiary Care Hospital, Journal of Patient Safety: September 2020; 16(3): e194-e198
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