Author: Michael Vlessides
Existing cardiac disease, pulmonary disease and obstructive sleep apnea are all significantly associated with an increased risk for postoperative opioid-induced respiratory depression. The findings, from a recent systematic review and meta-analysis, may help in the development of strategies to mitigate the risk for this complication.
“Postoperative opioid-induced respiratory depression is associated with very high morbidity and mortality rates,” said Kapil Gupta, MBBS, a clinical fellow in anesthesiology at the University of Toronto. “So the objective of this systematic review was to identify any potential associations between the patient, the procedural characteristics and postoperative opioid-induced respiratory depression. We believe this will ultimately help health care providers to plan medications, titrate opioids and enhance monitoring as necessary in this subgroup of patients.”
As part of the review, Dr. Gupta and his colleagues searched various databases for relevant studies published between 1947 and November 2017, including all adult surgical patients who were administered opioids during their hospital stay after surgery and had postoperative opioid-induced respiratory depression (OIRD). Data from a control group were also included. Prospective and retrospective studies were used in the analysis, as long as they reported both respiratory depression and risk factors that predicted or were associated with the occurrence of the adverse event. Other article types, specifically case reports, editorials and letters to journals, were excluded from the analysis.
Of a total of 8,690 citations, 12 studies comprised the final analysis. Reporting at the 2018 annual meeting of the International Anesthesia Research Society (abstract PS54), Dr. Gupta said the incidence of postoperative OIRD was 5 per 1,000 anesthetics (95% CI, 4.8-5.1; 4,194/841,424 total patients). Within the first 12 hours after surgery, 80% of cases of OIRD occurred, increasing to 85% within 24 hours postoperatively.
Several diseases were found to be significantly associated with an increased risk for OIRD, including preexisting cardiac disease (odds ratio [OR], 1.7; 95% CI, 1.2-2.5; P<0.002), pulmonary disease (OR, 2.2; 95% CI, 1.3-3.6; P<0.001) and obstructive sleep apnea (OR, 1.5; 95% CI, 1.2-1.8; P=0.0005).
The meta-analysis also revealed that the morphine equivalent dose of postoperative opioids was significantly higher in the group of patients who experienced OIRD (24.6±14 mg) than in the control group (18.9±13.0 mg; P=0.002). “As such,” Dr. Gupta said, “patients with opioid-induced respiratory depression received 23% greater morphine equivalent doses than did patients in the control group.” Hospital length of stay did not differ between the groups.
“We believe this is a very clinically relevant study,” Dr. Gupta replied. “Going forward, when we deal with patients who have preoperative cardiac disease, pulmonary disease or obstructive sleep apnea, we will enhance monitoring and be more careful with our titration and administration of opioids. We also recommend administering multimodal analgesia in this subgroup of patients, which will help by decreasing the amount of opioids they’re administered.”
Dr. Mosieri also asked, “Apart from enhancing the monitoring, would you cover them for longer periods in the PACU or do you advise that such patients go to a step-down unit? Because sometimes we’re worried about cardiac patients and our surgeons are not happy sending them to the floor. Can we keep these patients in the ICU overnight or perhaps a step-down?”
“I believe that’s a possibility,” Dr. Gupta replied. “As of now we don’t do that, but maybe we can increase the duration of stay in the PACU in these patients in the future.”