The Indianapolis Coalition for Patient Safety (ICPS) comprised of chief executive, medical, nursing, quality, and pharmacy officers from 7 Indianapolis Health Systems has studied and endorsed, in principle, the APSF recommendations for monitoring patient controlled analgesia (PCA) in the postoperative period.1,2 In January 2010, ICPS approved the following “Opioid-Induced Respiratory Depression” document consisting of “Facts, Recommendations, and Immediate Steps for Coalition Members.”
(1) Opioid-induced respiratory depression in postoperative patients occurs at an unknown incidence. Rates quoted in the literature range from 1-40% depending on the definition used. At least 3 Coalition hospitals have experienced known or suspected significant events related to opioid-inducted respiratory depression.
(2) Rates of opioid-induced respiratory depression are known to be higher among patients receiving continuous opioid infusions compared to PCA. By extension an opioid dosage regimen that is not related to demand by the patient (infusions or single injections in the neuraxis, transdermal techniques) may also put patients at increased risk of respiratory depression.
(3) The literature has delineated patient populations likely to be at higher risk for respiratory depression with postoperative opioids, including patients with sleep apnea, the opioid-naïve (for reference, a patients is considered not opioid-naïve if they have been receiving any form of opioid for 7 or more days preoperatively), the elderly and infirm, and those receiving other CNS depressants. However, patient not in these higher-risk groups can also suffer this complication.
(4) It appears that monitoring of patients receiving postoperative opioids can detect otherwise-unrecognized respiratory depression. It is unclear whether this recognition (and, presumably, intervention) will improve final outcomes, but it seems probable.
(5) Oximetry, while ubiquitous, easy to use, and relatively inexpensive, is a relatively poor detector of respiratory depression/hypoventilation, particularly in the presence of supplemental oxygen.
(6) Capnography is the most reliable detector of hypoxia and hypoventilation. It is unfortunately more difficult to use, less comfortable for the patient, and is prone to false positives related to equipment failures. Capnography is presently rarely used in hospitals outside of operating room settings, and implementation outside of ICU and PCU settings may be difficult. The capital requirements for monitoring all postoperative patients with capnography may be very large.
(1) Hospitals should develop an action plan with a timeline for implementation of monitoring for postoperative respiratory depression. It would be rational to begin with identified higher-risk patients.
(2) Ideally, patients would be monitored with both oximetry and capnography. If supplemental oxygen is not being administered, monitoring with only oximetry is acceptable. If supplemental oxygen is administered, monitoring with capnography with or without oximetry is desirable.
(3) A closed-loop system, which stops or pauses opioid dosing if respiratory depression is detected, is desirable. Systems are most ideally centrally monitored. In any case, alarms should be audible or otherwise available to the primary caregiver, and a mechanism for prompt response should be in place.
(4) Better screening for known factors that increase risk should be conducted on all patients, not just those who are pre- or postoperative.
(5) Coalition hospitals should reexamine the use of continuous-infusion PCA techniques, especially in patients known or considered to be at risk for sleep apnea and opioid-naïve patients. Consider whether continuous PCA infusions should carry automatic stop dates, limitations on duration, or requirement for reevaluation of the patient prior to continuing.
(6) Emphasis should be placed on administering supplemental oxygen only to patients where it is needed to maintain acceptable oxygen saturation.
(7) Hospital staff should be educated in the manifestations of this complication and how to monitor for it. Significantly, the treatment of hypoxemia in patients receiving opioids will generally include supplemental oxygen, which, in the absence of a concomitant intervention to support ventilation, is the wrong response in patients who are hypoxemic due to opioid-induced respiratory depression.
(8) Non-opioid pain relief techniques (regional and local anesthesia, nonsteroidal medications) should be encouraged to decrease opioid requirements.
(9) Selection of patients suited to PCA techniques should be better defined, and hospitals should revisit who is pushing the PCA button.
Immediate Action Steps for Coalition Members
(1) PCA: Reevaluate use of non-demand pain therapies for acute postoperative pain (continuous infusion PCA or neuraxial, transdermal, single shot neuraxial). Develop criteria for suitability of patients for PCA based on ability to self-dose, and consider limitations on duration of PCA. Develop family education materials to discourage family administration of PCA medications.
(2) Encourage use of non-opioid pain therapies (regional and local infiltration anesthesia/analgesia, nonsteroidal analgesics when appropriate, and other non-opioid adjuvants).
(3) Discourage use of routine postoperative oxygen supplementation, particularly if oximetry is used for postoperative monitoring of ventilation.
(4) Educate bedside caregivers on the possibility and recognition of respiratory failure with hypercapnea despite the absence of arterial hypoxemia, as when supplemental oxygen is being administered. Emphasis should also be placed on understanding that postoperative desaturation may be due to hypoventilation, and that the addition of supplemental oxygen or increased flow rates of supplemental oxygen are not necessarily the correct treatment.
Paul M. Calkins, MD
Sherman McMurray, MD
Diana McDowell, RN
Glenn J. Bingle, MD,PhD
Indianapolis Coalition for Patient Safety
- Weinger MB. Dangers of postoperative opioids. APSF Newsletter. 2006;21(4):61.
- Stoelting RK, Weinger MB. Dangers of postoperative opioids-Is there a cure? APSF Newsletter. 2009;24(2):25.