Revisiting PONV Prophylaxis

Most of us routinely administer decadron and zofran in the OR. Recently, I started at an academic medical center and noticed providers frequently use Haldol for PONV prophylaxis. Initially, I was completely against using this anti-psychotic medication as part of my PONV regimen. However, with a little bit of knowledge and research, I’ve changed my practice and want to share why.

Prior to the FDA black box warning, Droperidol + Zofran combination was considered the gold standard anti-emetic regimen. Today, if a provider wanted to use droperidol, all other anti-emetic options would have to be exhausted, the patient would need a 12 lead EKG prior to administration and after administration 2-3 hours of continous EKG monitoring. This sounds like overkill in my opinion! Hence, the utilization of Haldol. Haloperidol (Haldol), like droperidol, is a dopamine 2 antagonist. Recall that dopamine acts on the chemoreceptor trigger zone (CTZ) of the vomiting center. When the vomiting center is activated, the emetic reflex occurs leading to vomiting. Now back to the topic at hand. Literature shows that 1mg IV of Haldol is an effective anti-emetic dose without causing extra-pyradimal symptoms. The side effect profile, directly correlates to the dose and plasma concentration of the drug. Haldol also has a half life of 10-20 hours.

Now, for the truth about ondansetron (zofran). Zofran is a good drug with a relatively low side effect profile and works great as an anti-emetic. Zofran is a 5HT3 (serotonin) antagonist and acts on the CTZ and vagal afferent system. The prophylactic dose is 4mg IV, while the rescue dose is 1mg IV! I’d be curious to know how many readers knew the rescue dose was decreased. If you practice how I once did and administer 4mg IV zofran at the end of the case and order it again for PACU, just know, you are not helping the PACU nurses or your patient if they experience PONV. Once the 4mg IV dose is administered, studies show zofran is no longer effective as a rescue. Hence, I’ve stopped giving zofran in the OR and I order it for PACU.

Finally, a quick overview of dexamethasone (decadron). No one really knows the mechanism of action of decadron, but animal studies have shown decadron to act on the vomiting center and is comparable to 4mg IV zofran and 1.25mg IV droperidol (the former gold standard). From my experience, it seems most providers give either 4mg IV, 6mg IV, or 8mg IV and higher doses at the request of the surgeon. For all of you 4mg’ers out there, the minimum effective dose of decadron is 5mg!

My regimen, 8mg IV decadron at the beginning, and 1mg IV haldol at the end. Zofran for the PACU orders!

If any of you use haldol for PONV prophylaxis, I’d love to hear your experiences with the medication.

Side note: thanks to the blog owner for having me as a guest writer. I hope the information was useful. -ULCRNA

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