Search our site 
Advanced Search
Home | Exam dates | Contact us | About us | Testimonials |

You are in Home >> Resources >> Clinical anaesthesia >> Nausea and vomiting

General principles of PONV

Created: 13/4/2004

Postoperative nausea aand vomiting (PONV may be the most unpleasant memory associated with a patient’s hospital stay. Severe cases can lead to increased length of hospital stay, increased bleeding, incisional hernias and aspiration pneumonia. Prolonged vomiting results in loss of hydrogen, chloride, potassium, sodium and water. Dehydration, metabolic alkalosis and total body potassium depletion may occur. The incidence of PONV in adults is approximately 25%, ranging from 5-75% in the literature.

The best anti-emetic drug or antiemetic strategy has a numbers needed to treat (NNT) of about 5.

The concept of the NNT

The NNT is an indicator of treatment effect in clinical trials. It is calculated as [1/ absolute risk reduction]. This gives an indication of the size of treatment effect. Hence, an anti-emetic with NNT of 5 equates to treating five patients in order to prevent one patient vomiting.


i] The effective management of post-operative nausea and vomiting. Aesculapius Medical Press. Strunin L, Rowbotham D, Miles A (1999).

ii] The "big little problem" of postoperative nausea and vomiting: do we know the answer yet?
Fisher DM.
Anesthesiology 1997; 87: 1271-3.

iii] Using numerical results from systematic reviews in clinical practice.
McQuay HJ, Moore, RA.
Ann Intern Med 1997; 126: 712-20.


SiteSection: Article
  Posting rules

     To view or add comments you must be a registered user and login  

Login Status  

You are not currently logged in.
UK/Ireland Registration
Overseas Registration

  Forgot your password?

All rights reserved © 2021. Designed by AnaesthesiaUK.

{Site map} {Site disclaimer} {Privacy Policy} {Terms and conditions}

 Like us on Facebook