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