Paediatric postoperative vomiting and nausea - prophylaxis and treatment

Overview

• Post-operative vomiting (POV) is distressing for children and their parents. Vomiting may, in addition, have medical consequences such as dehydration and wound dehiscence.

• POV occurs in 17% of Starship patients but in higher risk groups 50% of patients vomit, (local audit 2017). Antiemetic prophylaxis is variably given. A clear department guideline on risk scoring and prophylaxis would be expected to reduce the vomiting incidence.
  

Risk scoring tool for ALL patients presenting for general anaesthesia 

Treatment tool for patients with vomiting or nausea after an anaesthetic

Antiemetic Choice

Evidence based support for the following three anti-emetics in children

Dexamethasone

• No clear dose response

• Suggested dose 0.15mg/kg up to maximum total dose of 8mg

• Better effect at preventing late vomiting compared to ondansetron

Ondansetron (or other 5HT3 antiemetics)

• There is a dose related response with the optimal prophylactic dose 0.15mg/kg up to a maximum total dose of 4mg

• May be given iv or orally for prophylaxis

• Timing i.e. or beginning or end of surgery does NOT make a difference

Droperidol

• Effective for prophylaxis and treatment

• Dose 0.025mg/kg up to a maximum total dose 0.75mg

Relative contraindications and contraindications to Antiemetics

Dexamethasone

• Patients at risk of tumour lysis

• Patients at high risk of infection

• Unstable diabetic patient

• Allergy or prior side-effects

• Active oncology patients

  • If the situation is unclear and you wish to use dexamethasone, contact the primary on-call oncologist, if after hours, for discussion.

Ondansetron

• Risk of torsades in long QT syndrome

• Allergy or prior side-effects

Droperidol

• Risk of torsades in long QT syndrome

• Allergy or prior side-effects

Anaesthetic Modifiers effective in reducing POV

• Total intravenous anaesthetic with propofol

• 30ml/kg fluid in day-stay surgery

Risk Factor Assessment

• Risk factors related to patient, surgery and anaesthetic – follow this link for a detailed discussion of all risk factors.

• Eberhart paediatric risk assessment tool

  • has 4 risk factors –

    • AGE >3, ANAESTHETIC LENGTH > 30 minutes, STRABISMUS surgery, HISTORY in child or sibling or parent –

    • each score one point

    • validated tool

  • VPOP is an alternative validated patient risk assessment tool but Starship anaesthesia has chosen Eberhart for its simplicity and ease of use

Risk of post-operative vomiting is as per table

Rationale for Prophylactic Antiemetics

• Beneficial to target anti-emetics at high risk group where there is likely to benefit

• Waste of health resources, financial cost and risk of side-effects greater than benefit to give prophylactic anti-emetics to low risk groups

Expected Benefit from Prophylactic Antiemetic                                     

• Reduction in risk by 1/3 for each agent added

Suggested Number of Antiemetics

• None or one risk factor – no prophylactic anti-emetics, treat POV should it occur

• Two or more risk factors give two prophylactic anti-emetics

• Three or more risk factors in addition to prophylactic antiemetics modify anaesthetic management

Postoperative Vomiting (and Nausea) Management

See treatment tool above

• Check for other causes if persistent - electrolyte disturbance especially hyponatremia, gastric stasis or ileus or bowel obstruction (will a nasogastric help?), severe pain
  

• IF postoperative vomiting (or nausea) then give the antiemetics in the following order (provided no contraindications) if NOT given yet:

  • Ondansetron

  • Dexamethasone

  • Droperidol
    

• If all three given contact pain team or anaesthetist for further advice

Other Treatment Choices

Evidence for acupuncture and acupressure

• Effective

• Acupuncture more effective than acupressure or electrical stimulation

• Not currently available at Starship

Scopolamine

• Adult evidence

• Consider in a teenager

Aprepitant

• Adult evidence

• May be possible for older child, special authority would be required.

NO evidence that cyclizine is useful

• 2 paediatric studies both negative i.e. no useful antiemetic effect

Metoclopromide is NOT a reliable antiemetic in children and is not recommended

Prochlorperazine is NOT recommended as no evidence of effectiveness in children