MMC Post-Operative Nausea/Vomiting (PONV) Algorithm
for Adults w/ General Anesthesia
version December 2009
R. Hubbs

RISK Factors
Risk Factors for PONV (simplified): A. History of PONV
B. Nonsmoker
C. Female
D. Post-op opioids (anticipated/required for pain control)
Very High Risk:
A.  Multiple past histories of PONV (despite prophylactic treatment)
B.  History is important, especially whether the patient has likely failed prophylaxis in the modern era of propofol, sevo/iso, ondansetron, and dexamethasone
C.  Best identified in the preoperative screening process in the days before elective surgery

Management # of Risk Factors
Timing 0-1 1-2 2-3 3-4 4 Very High Risk
Preop Therapy: N N N N Scop' Patch
or Aprepitant
Scop' Patch
or Aprepitant
Intra-Op Therapy:  
at start
N Y  Y Y Y Y
at end
N N  Y Y Y Y
Propofol Infusion N N  N Y Y Y
Avoid N2O
Give Ample Fluids
N  N N Y Y Y
at start
N N N N  N Y
PACU Protocol (below) Y Y Y Y Y Y

PACU Protocol (drugs to give preferentially in this order):
1 Ondansetron 4 mg if not given in last 6 hours
2 Haloperidol 0.5 mg may repeat up to 2 mg
3 Promethazine 6.25 mg may repeat x 1
4 Scopalamine patch behind ear
5 Dexamethasone 4 mg x 1 in PACU 
(given slowly & if not already given intraop)

Prevention of Post-Discharge Nausea & Vomiting

If patients have persistent or significant N/V in the PACU and are having ambulatory surgery, discharge options are as follows:

Scopalamine patch behind ear
Dexamethasone 4 mg IV x 1 in PACU 
(given slowly & if not already given intraop)
8 mg disintegrating tablet PO q 6 hours 
(must pass duodenum to be effective)
Promethazine suppositories  
Oral dimenhydrinate (Dramamine©)  


Medication Options:

4 mg IV



Mechanism: Steroid
Side effects: Insomnia, may worsen diabetic glucose control (but this is rarely a reason not to use it), can cause perineal burning if not given slowly to an awake patient (which is why we give it after induction)
Note: Controlled, randomized trials have shown no benefit to giving more than 4 mg. Onset is on the order of hours, which is also why it is given early in the case and is not great as a rescue drug.
give slowly IV in awake patient to reduce mucous membrane sensation.
do NOT give to lymphoma /leukemia patients without checking with oncologist.

4 mg IV

Mechanism: 5HT3 antagonist
Side effects: Headche, prolonged QT interval
Note: Controlled, randomized trials have shown no benefit to giving more than 4 mg. They have also shown no benefit for repeating the dose less than 6 hours after the last dose

6.25 – 25 mg IV 
(divided doses of 6.25 mg)


Mechanism: Antihistamine
Side Effects: Sedation; can cause severe tissue necrosis if extravasated or given intra-arterial (always give slowly in a well running IV, no IV push)
• Now has an FDA black box warning regarding the above. The MMC Pharmacy and Therapeutics committee is reviewing the options to form a policy. It is possible we may substitute dimenhydrinate (IV Dramamine) for promethazine.

Haloperidol (Haldol©
0.5 – 2.0 mg IV 
(divided doses of 0.5 mg)

Mechanism: Dopamine antagonist (similar efficacy to droperidol)
Side effects: Sedation, QT prolongation
Note: Low dose therapy is considered relatively safe, seemingly as safe as the 5HT3s

Scopolamine Patch 
1.5 mg behind ear


Mechanism: Anticholinergic
Side effects: Blurred vision, dry mouth, contraindicated in patients with narrow-angle glaucoma (a relatively rare type of glaucoma, most patients with glaucoma do not have this type). May not be the best choice for elderly patients as it may cause confusion.
Note: Onset of action is on the order of several hours. Ideally given the night before surgery or very early on the day of. Still, in high risk patients it is sometimes warranted even if started right before the OR.
• May be left on for 72 hours if needed. Many patients remove it the day after surgery if they are doing well. They should be instructed to wash their hands after removal so they don't inadvertently get the drug in their eye which can cause blurred vision, dilated pupil.

Propofol Infusion

Mechanism: Not clear, but it works.
• Must be given as IV infusion throughout case for prophylaxis.
o Minimally effective dose for PONV prophylaxis has been shown to be about 20 mcg/kg/min (but may give higher dose as well if you want to reduce inhaled agents). Can also be used as TIVA with remifentanil, etc.
• Can sort of be used post-op but this is a very short term option and not practical in most situations. 10-20 mg IV lasts a few minutes.
• Do not use nitrous if using a propofol infusion because it defeats the purpose to some extent

Aprepitant (Emend©
40 mg PO
 a very new  drug for PONV 


Mechanism: Substance P / NK1 receptor antagonist
Side effects: Thus far few have been reported. However, it's a new drug and side-effects may come to light in time. Adverse reactions have been reported as part of a combination chemotherapy regimen or with general anesthesia (therapies which have many confounding side-effects). It does inhibit the CYP3A4 metabolic pathway for certain drugs, but this is rarely an issue with single doses.
Note: One dose offers 48-72 hours protection, goal is to give within 3 hours prior to surgery, use this as part of a multi-modal approach
Expensive: $40 / pill
• An IV form is available — probably more expensive, not yet on formulary to my knowledge.

Metoclopramide (Reglan©)

Note: Randomized trials have shown no benefit of 10 mg.
• Doses of 25-50 mg may be effective
Side effects: dystonia, extrapyramidal symptoms
• Given the other options, I think it should be rarely used for most patients.