The Case • 36 year-old female, ASA 1, under went an elective repeat caesarean section under spinal anesthesia using hyperbaric bupivacaine15mg + fentanyl 10 ug. She delivered a 3.0 k baby boy, 30 minutes after cutting. After which she complained of nausea and vomiting. Metoclopramide 10 mg IV was given but vomiting recurred.
The Clinical Question Among ASA 1 adults who will under go elective caesarian section under spinal anesthesia, what effective anti emetic can be used to prevent intra operative nausea and vomiting?
The Journal • Subhypnotic doses of midazolam, prevent nausea and vomiting during spinal anesthesia in elective caesarean section • Tarhan, O et al. • Minerva Anestesiologica 2007; 73 629 - 633
The Journal • Patients: • Ninety , ASA I – II, 28 – 30 yo, for elective ceasarean section under SAB using bupivcaine heavy 8 -10 mg + fenatnyl 10 ug • Intervention: • Patients grouped into 3, given: • Propofol, Midazolam, or Saline • Comparison: Saline as control • Outcome: nausea, retching, vomiting, sedation
The Journal Outcome: Scoring for emesis • 0 = No symptoms • 1 = Nausea (unpleasant sensation of vomiting) • 2 = Retching (spasmodic contraction of abdominal wall and diaphragm without expulsion of gastric content ) • 3 = Vomiting (same as 2 but with expulsion of gastric contents
The Journal • Outcome: sedation • Ramsay sedation scoring • 1 : awake , agitated, anxious • 2: awake, cooperative, oriented, tranquil • 3: semi - asleep but follows command • 4: asleep but briskly responds • 5: asleep with sluggish response • 6: no response can be elicited
Assessing Validity 1. Where patients randomly assigned to treatment groups • Yes. Patients were randomly assigned to three treatment groups . Randomization was through computer generated random numbers
The treatment groups • The test substances were given immediately after cord clamping • Propofol (20 mg as bolus, 1 mg/kg/hr as infusion) : N = 30 • Based on Numazaki et al • Midazolam (1 mg as bolus, 1 mg /hr infusion) : N = 30 • Based on Di Florio et al
Assessing Validity 2. Was allocation concealed? • Unclear. No mention of concealment of allocation although infusion pump and syringes where assigned number by personnel not involved in the study
Assessing Validity 3. Were the groups similar at the start of the trial? • Yes, patient demographicdata was similar between the groups (analyzed using ANOVA and chi-square test)
Assessing Validity 4. Were patients treated equally? • Yes • Ranitidine 150 IV mg preop • Preloading 20 ml/ kg of PLRS before induction • Bupivacaine 8 – 10 mg + Fenatnyl 10ug given intrathecally L3 – L4 • O2 at 5 lpm via mask • 20% decrease in BP or (or below SBP <100) treated by fluids and ephedrine 5 – 10 mg IV • Fentanyl 100 ug given post op prn for pain
Assessing Validity 5. Were patients and caregivers/ outcome assessors blinded to treatment assignment? • Yes, identical syringes and infusion pumps were prepared and covered then assigned numbers by a personnel not aware of the study. Emetic episodes were recorded by an anesthesiologist who was not aware of the endpoints
Assessing Validity 6. Were all patients who entered the study accounted for ? • Yes, 2 patients in the control group had to be given rescue anti emetics and were withdrawn, leaving the group with 28 subjects
The incidence of nausea, retching and vomiting is higher in the control group compared to the propofol and midazolam group (P value <0.05%)
Appraising the results 1. How large was the treatment effect? • Relative risk (RR) : < 1 ( there is a decrease in the event)
Appraising the results 1. How large was the treatment effect? • Absolute risk reduction (ARR) : % Reduction of the event
Appraising the results 1. How large was the treatment effect? • Relative risk reduction (1-RR): % Reduction of the event in relation to the control
Appraising the results 1. How large was the treatment effect? • Number needed to treat
Appraising the results 1. How precise was the measurement of the treatment effect? • P values obtained for both midazolam and propofol versus control were less than 0.05 % = statistically significant.
CONCLUSION • A subhypnotic dose of midazolam (1mg/hr) is as effective as subhypnotic dose propofol (1mg/kg/hr) for the prevention of nausea and vomiting in parturients undergoing elective caesarean section under spinal anesthesia
Assessing applicability • 1. Is my patient so different to those in the study that the results cannot apply? • Based on the demography, the results are applicable to our patients.
Assessing applicability 2. Will the results help me in caring for my patient? • This study has informed me that midazolam and propofol can be used as anti emetic during elective caesarian section under spinal anesthesia HOWEVER
Assessing applicability 3. Is the treatment feasible in my setting? • Limitation: • Elective caesarean section • Cost • Availabilty of infusion pump