| Methods |
Randomized, double‐blind, controlled trial |
| Participants |
Healthy adolescent patients scheduled for orthognathic surgery. Forty‐six (46) consecutive patients considered eligible; excluded 7 as below, leaving 19 for the clonidine group and 20 for the placebo group
Exclusion criteria: significant heart disease that contraindicated the use of controlled hypotension, medically important liver or kidney dysfunction, allergy to clonidine, allergy or contraindication to the use of labetalol or β‐blocking drugs, weight heavier than 80 kg, and inability to comply with the protocol, i.e., a language barrier
Excluded 6 patients (patient refusal, language barrier, or weight heavier than 80 kg). One patient who had initially consented to participate refused to take the study drug, and his data were not included in the analysis |
| Interventions |
Experimental group: clonidine 5 μg/kg orally at bedtime the night before surgery and 90 min prior to induction (rounded to nearest 50 μg)
Control group: identical‐looking placebo at the same times |
| Outcomes |
Morphine or codeine given in PACU
PACU length of stay
Haemodynamic values before surgery and at induction
Preoperative sedation
Temperature
Time to arrival in PACU
Time to eye opening
Time to movement to command
Extubation |
| Notes |
Primary outcome of this study was controlled hypotension perioperatively, but also reported on analgesic requirements postoperatively; note that fentanyl was given intraoperatively to control BP (different amounts to each group) |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Randomization by hospital pharmacy using a table of random numbers |
| Allocation concealment (selection bias) |
Low risk |
Communication with Dr. Hackmann: "Only the pharmacists knew to which study group the patients were assigned." "The randomization code did not have to be broken for any of the study participants." "Only after all patients had completed the study were the assignments revealed to the authors so that statistical analysis could be performed." |
| Blinding (performance bias and detection bias)
All outcomes |
Low risk |
Explicitly states that "the patients, investigators, surgeons, and nurses involved in the patients’ care were blinded to the nature of the assignment ". |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
Appears to be satisfactory; 7 out of 46 patients excluded for various reasons (distribution between groups not stated) |
| Selective reporting (reporting bias) |
Unclear risk |
None evident |
| Other bias |
Low risk |
None considered to be significant. Height in control group slightly less than that in clonidine group (159 ± 6.9 versus 166 ± 10.4, P=0.02) but no difference in weight or other demographical and surgical characteristics |
