Hepatic Failure/GI/Endocrine Emergencies

A multimodal strategy that usually targets risk avoidance should be implemented to avoid PONV.

The IMPACT study enrolled more than 5000 surgical patients and evaluated six interventions for the

prevention of PONV in a factorial design, including avoidance of volatile anesthetics and nitrous oxide,

use of short-acting opioids in the postoperative period, and use of ondansetron, dexamethasone, and

droperidol for pharmacologic prophylaxis. Each intervention except for choice of opioid was associated

with a reduction in the incidence of PONV; however, the study showed that the interventions acted

independently of each other, and thus, a benefit with several interventions was seen.

anesthetics are associated with an 11-fold increase in PONV. If general anesthesia is required, propofol

is preferred to volatile anesthetics for inducing and maintaining anesthesia. In the IMPACT study, the

use of propofol compared with volatile anesthetics was associated with a 19% relative risk reduction in

the incidence of PONV (p<0.001).

Avoiding nitrous oxide as a carrier gas is recommended; use of other carrier gases (e.g., nitrogen,

oxygen) is associated with a 12% relative risk reduction in PONV (p=0.003).

Perioperative opioid use should be minimized, if possible. Guidelines recommend the use of perioperative

NSAIDs for opioid-sparing analgesia. Intravenous acetaminophen has also been studied as part of a

multimodal analgesia strategy to reduce postoperative opioid use; although oral acetaminophen may

also be used, its effect on PONV has not been well studied. According to data from the IMPACT

study, which compared remifentanil with fentanyl, the use of short-acting opioids does not appear to be

associated with the incidence of PONV.

Pharmacologic prophylaxis:

Serotonin-3 antagonists are first-line treatment for pharmacologic prophylaxis. These drugs are

most effective for the prevention of PONV when given at the end of surgery.

Ondansetron, when given at a prophylactic dose of 4 mg intravenously, has greater anti-

vomiting effects (number needed to treat [NNT] = 6) than antinausea effects (NNT = 7).

ii.

Granisetron at doses of 0.35–3 mg intravenously is as effective as ondansetron, whereas

palonosetron 0.075 mg intravenously was more effective than ondansetron at preventing PONV

in a small study of gynecological laparoscopic surgical patients (42% PONV with palonosetron

vs. 67% with ondansetron, p<0.05). Palonosetron is a second-generation serotonin-3 antagonist

with longer half-life than other agents.

Dexamethasone is most effective for the prevention of PONV when given at the time of induction.

According to data from the IMPACT study, dexamethasone 4 mg intravenously was associated

with a 26% relative risk reduction in the incidence of PONV.

ii.

A recent study evaluating a higher dexamethasone dose (e.g., 8 mg intravenously) at the time

of induction for the prevention of PONV found that this high-dose strategy resulted in an 8%

absolute risk reduction in vomiting compared with standard PONV care.

iii.

When used for PONV, dexamethasone may cause modest increases in blood glucose in patients

both with or without diabetes.

Droperidol at prophylactic doses of 0.625–1.25 mg intravenously is effective for the prevention of

PONV when given at the end of surgery.

Efficacy of droperidol is similar to that of ondansetron and dexamethasone, with a relative risk

reduction of about 25% (data from the IMPACT study).

ii.

FDA black box warnings for cardiovascular risk with droperidol have limited its use; however,

the doses used for preventing PONV are very low and are unlikely to be associated with

cardiovascular effects.