IV APAP of Little Benefit for Cardiothoracic Post-op Pain – Pain Medicine News – by Kenneth Bender – Aug 2019
This is an amazingly honest negative evaluation of IV Tylenol, which some people claimed was just as effective as opioids. But this study is a reality check and brings more science and less hype to the overcrowded field of opioid/pain studies.
Intravenous acetaminophen provided little benefit in multimodal analgesia regimens for cardiothoracic postoperative pain and posed a risk for hypotension, according to a study of outcomes in a real-world population.
I’m thrilled to hear it stated so definitively after so many years of hearing how great of a pain killer Tylenol is.
Paul Thill, PharmD, a professor of pharmacy practice in the College of Pharmacy at Ferris State University, in Big Rapids, Mich., and his colleagues noted the expectation that IV acetaminophen could serve as the nonopioid component of multimodal analgesia for cardiothoracic postoperative pain, with the recent contraindication of IV ketorolac for use after coronary artery bypass grafting, “bringing into question the safety of NSAIDs [nonsteroidal anti-inflammatory drugs] in this setting.”
Although multimodal analgesia with systemic nonopioids has been studied and implemented in the cardiothoracic surgery population, Dr. Thill observed, “further investigation is warranted, but hope is dimming for reliance upon IV acetaminophen as the nonopioid cornerstone of a multimodal approach.”
His words are directly contrary to all the current hype about using just Tylenol during operations and sending patients home afterward with more of it.
From all the other articles lately praising Tylenol and claiming it can be substituted for opioids, you’d this it was the perfect wonder drug. But it’s not even close.
To ascertain outcomes from this use of IV acetaminophen in a real-world population, Dr. Thill and his colleagues compared the medical records of 92 patients who had received at least one dose in the immediate post-cardiothoracic operative period with those of 166 similar patients who did not receive the drug.
The primary study outcome was quantity of opioid analgesic used in the first 24 hours after surgery, measured in morphine milligram equivalents (MME).
IV Acetaminophen Not Opioid Sparing
The investigators reported that there was no reduction in MME associated with administration of IV acetaminophen.
And here again, all those previous claims about its opioid-sparing effects seem to have been more wishful thinking than reality.
Dr. Thill and his colleagues reported that the groups did not differ in requirement for a vasopressor, but that 28% of those receiving acetaminophen experienced an infusion-related episode of hypotension.
The hypotension, which has been associated with IV acetaminophen in a study by Maxwell et al (Ann Pharmacother [Epub May 3, 2019]. https://journals.sagepub.com/ doi/ full/ 10.1177/ 1060028019849716), poses “a potential adverse effect of particular significance to this fragile population coming off bypass,” Dr. Thill said.
“The mechanism of the hypotensive effect is unknown,” Dr. Thill added
Dr. Thill and his colleagues concluded that IV acetaminophen does not reduce opioid requirements in the first 24 hours after cardiothoracic surgery, and that the infusion could pose harm from hypotension.
“This agent is often promoted as an answer to reduce opioid requirement,” said Dr. Thill, “and in our real-world application, patients did not achieve this desirable, albeit surrogate, end point.
I wish more experiments and studies were run in conditions more closely resembling the real world. Results achieved in some strictly controlled environment will rarely mimic the results seen with real people in their real lives doing real things.
Mixed Evidence of IV Acetaminophen Effectiveness
Clinical assessments have presented a mixed picture of the utility of IV acetaminophen for postoperative pain. In one, investigators concluded that IV acetaminophen did not decrease persistent surgical pain after cardiac surgery.
In another study, IV acetaminophen reduced pain intensity scores, but not opioid consumption after cardiac surgery
“The attempt at documenting real-world implementation of IV acetaminophen was important,” said Dr. Thill, “but prospective, real-world designs are optimal and should include measurements of adverse events such as blood pressure reductions and pressor use.”