Does giving liberal intra-op fluids reduce PONV in children?

The very ink with which history is written is merely fluid prejudice. – Mark Twain

 

Ashok V, Bala I, Bharti N, Jain D, Samujh R. Effects of intraoperative liberal fluid therapy on postoperative nausea and vomiting in children—A randomized controlled trialPediatr Anesth. 2017;27:810-815. https://doi.org/10.1111/pan.13179

 

Clinical Question

  • Does intraoperative liberal fluid therapy with crystalloids affect post-operative nausea and vomiting (PONV) in children undergoing lower abdominal and penile surgery?

 

Design

  • Single centre, randomised trial
  • Double blind computer generated randomisation to “restricted group” or “liberal group”
  • Blinding of patients, parents, surgeons, Post- Anaesthesia Care Unit nurses and post-operative investigator
  • Powered at 80% with sided alpha significance of 0.05
    • Sample size calculated at 67 patients per group
    • 150 patients enrolled to account for dropouts

 

Setting

  • Single hospital in India

 

Population

  • Inclusion
    • Age 3-7 years
    • ASA 1 or 2
    • Elective lower abdominal and penile surgery of <60 minutes scheduled duration
  • Exclusion
    • Antiemetic therapy within 24 hours before surgery
    • Cardiovascular and renal disease
    • Past history of PONV in patient, sibling and/or parent
    • History of motion sickness,
    • Obesity (BMI >30)
    • Developmental delay
    • Children whose parents could not be contacted by telephone
    • Contraindication to caudal block
  • 150 patients assessed for eligibility, nil excluded – 75 randomised and allocated to each group
    • 145 patients completed study (3 lost to follow up in group 1, 2 lost to follow up in group 2)
  • Baseline characteristics comparable between groups: age, weight, male:female, type and duration of surgery; heart rate, oxygen saturation and mean arterial pressure (data not provided).

 

Intervention and Control

  • Restricted group – 10 ml/kg/hr dextrose-free Ringer’s lactate
  • Liberal group – 30 ml/kg/hr dextrose-free Ringer’s lactate

 

Management common to both groups

  • Premedication with oral midazolam
  • Gas induction of sevoflurane in oxygen, maintenance of sevoflurane in 60% nitrous oxide in oxygen
  • Caudal block with 0.75 ml/kg 0.25% plain bupivacaine
  • IV fluid via infusion pump administered by non-blinded anaesthetist
  • No intraoperative opioids, antiemetics or muscle relaxants
  • Paracetamol IV at skin closure
  • Ondansetron given at first episode of PONV

 

Outcome measures

  • Primary efficacy endpoint: no nausea or vomiting with no administration of any antiemetic medication during the 24 hours postoperatively
  • All episodes of nausea, retching and emesis during 24 hours postoperatively
  • Time to child asking for oral fluids
  • Post-operative pain assessed using FLACC (face, legs, activity, cry, consolability) pain scale
  • Parental satisfaction: 0-10: (0=completely unsatisfied; 10=completely satisfied)

 

Results

  • PONV was significantly less in liberal group [n= 20 (27.4%)] compared to the restricted group [n=33 (45.8%)]
    (relative risk 0.59, 95% CI: 0.37-0.93, P=.021)
  • Adjusted odds ratio of PONV liberal vs restricted group 2.24 (95% CI: 1.12-4.48, P=.022) after regression analysis
  • NNT = 5.4
  • Secondary findings
    • Less thirst
    • Overall better patient satisfaction
    • Lower rates of antiemetic administration
      No difference in analgesic requirement
  • No evidence of adverse events including fluid overload and no significant difference in post-operative admission rates.

 

Authors’ conclusions

  • The administration of 30 ml;/kg/hr intravenous fluid intraoperatively significantly reduces the incidence of PONV in children undergoing lower abdominal and penile surgeries.
  • Children who received liberal fluids also had less thirst postoperatively, greater parental satisfaction with management of PONV symptoms

 

Strengths

  • Appropriate methodology for study question
  • Successful randomisation with comparable groups

 

Weaknesses

  • Actual administered volume of fluids given to each group not defined

 

Conclusions

  • In patients without risk factors for PONV undergoing short duration lower abdominal and penile surgery (<60 minutes) liberal fluid administration reduced post-operative nausea and vomiting when no prophylactic antiemetics were used, and reduced post-operative thirst.
  • These findings are in keeping with other studies of the effect of fluid regimens upon PONV.
  • Low NNT for benefit with low risks of harm due to the intervention.
  • Non-administration of prophylactic anti-emetics is not routine practice in our institution.

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