FRCA Notes

Paediatric Post-Operative Nausea and Vomiting

The curriculum asks for knowledge of 'the management of postoperative pain, nausea and vomiting in children'.

Resources

  • PONV is 2x more frequent in children compared to adults, with an overall incidence of paediatric PONV of 13-42%
  • This is somewhat age-dependent, witha sharp increase in risk at 3yrs age and increasing risk each year into adolescence
    • It is lower in infancy (<1yrs); 5%
    • In preschool children; 20%
    • It is higher in those >5yrs; 34-50%

Complications of PONV in children
Wound dehiscence
Dehydration
Electrolyte imbalance
Aspiration
Unanticipated admission after day-case surgery
Patient dissatisfaction

Patient factors

  • Age (as above)
  • Previous history of PONV
  • Family history of PONV
  • Previous history of motion sickness (but low PPV of 64%)
  • Female gender (but only once puberty started)

  • Some patient factors known to alter risk of PONV in adults have not shown the same associated in children, including:
    • Pre-operative anxiety
    • Obesity
    • Smoking status

Surgical factors

  • Duration of surgery >30mins (OR 3.25)
  • Type of surgery:
    • Strabismus surgery (OR 4.33)
    • Adenotonsillectomy (89% without prophylaxis)
    • Otoplasty (60% without prophylaxis)
    • Herniotomy | orchidopexy | penile surgery

Anaesthetic factors

  • Volatile agents
  • Peri-operative opioid use (especially long acting agents)
  • Use of anticholinesterases
  • Use of intra-operative fluids reduces risk of PONV, but mandatory post-operative PO fluids may increase risk of PONV and delay discharge

  • Some patient factors known to alter risk of PONV in adults have not shown the same associated in children, including use of nitrous oxide

Risk stratification

  • In the simplified risk score for POV in children (POVOC score), the patient scores one point for each of:
    1. Age ≥3yrs
    2. Surgery ≥30mins
    3. Strabismus surgery
    4. Personal or family history of PONV

  • Total score reflects risk of PONV:
POVOC score Risk of PONV
0 9%
1 10%
2 30%
3 55%
4 70%


Prevention

  • Pre-medication with clonidine or dexmedetomidine
  • TIVA technique
  • Opioid-sparing, multi-modal analgesia
  • Early and liberal return to fluid intake post-operatively

Ondansetron

  • Dose (max 4mg)
    • In patients <6months: 0.1mg/kg
    • In those >6months: 0.15mg/kg as this was associated with a lower NNT to prevent early and late vomiting compared to 0.1mg/kg
  • Oral route as effective as IV route
  • Timing of administration makes no difference to effectiveness

  • Does not produce clinically significant QTc prolongation in healthy children, but should be avoided in patients with long QT syndromes
  • As effective as dexamethasone (early vomiting, but dex. better for late vomiting), and more effective than metoclopramide or droperidol

Dexamethasone

  • Dose: 0.15mg/kg (max. 6.6mg)
  • Contraindicated in patients at risk of tumour lysis syndrome e.g. non-Hodgkin's lymphoma, acute leukaemia

Droperidol

  • Dose: 0.025mg/kg (25μg/kg)

  • More effective in controlling nausea than vomiting
  • Should be used as a rescue therapy owing to concerns about side-effects

  • Issues include:
    • Sedation
    • Prolonged QTc
    • Extra-pyramidal side-effects

Others

  • Metoclopramide is not recommended owing to lack of efficacy and increased risk of extrapyramidal side effects
  • Prochlorperazine and cyclizine lack a strong evidence base for use in children, and are not recommended
  • Transdermal scopolamine may play a role in adolescents but is not recommended for use in younger patients

  • P6 acupuncture point stimulation is more effective than placebo and potentially as effective as somee anti-emetic drugs