Effect of hypotensive anesthesia in orthognathic surgery
Patients
Adults subjected to orthognathic surgery
Intervention
Hypotensive Anesthesia
Comparison
Normotensive Anesthesia
Outcome
Absolute effect*
Certainty of evidence (GRADE)
WITHOUTHypotensive anesthesia
WITHHypotensive anesthesia
Intraoperative blood loss
524 ml
355.32 ml
⊕⊕◯◯1,2Low
MD: 168.68 ml less(Margin of error: 228.19 ml less to 109.77ml less)
Surgical time
248 min
238.54 min
⊕⊕◯◯1,3Low
MD: 9.46 min less(Margin of error:22.87 min less to 3.95 min more)
Quality of surgical field+
The quality of surgical field assessment scale was on average 0.66 standard deviations lower in the hypotensive group
⊕⊕◯◯1,2Low
SMD**: 0.66 less(Margin of error: 1.05 less to 0.28 less)
Adverse effects
The included systematic reviews did not report adverse events like renal, hepatic, cardiac or cerebral hypoperfusion during surgery.
Mortality
The outcome mortality was not measured or reported by included systematic reviews
Margin of error: 95% confidence interval (CI).MD: Mean difference.SMD: Standardized mean difference.GRADE: Evidence grades of the GRADE Working Group (see later).+: The studies reported the quality of the surgical field using different assessment scales, where lower scores indicated better quality of the surgical field.*The risk WITHOUT hypotensive anesthesia is based on the risk in the control group of the trials. The risk WITH hypotensive anesthesia (and its margin of error) is calculated from relative effect (and its margin of error).**The standardized mean difference is used when the outcome has been measured on different scales, being difficult to interpret clinically. It is commonly accepted that values close to 0.2 would have little clinical relevance, values of 0.5 would have moderate relevance (clinically recognized) and values above 0.8 would have high relevance.1 The certainty of evidence was downgraded in one level for risk of bias since in most of the included trials there were a lack of description of the randomization method, lack of blinding, and inadequate allocation concealment of patient randomization.2 The certainty of evidence was downgraded one level for inconsistency due to trials presenting different conclusions (I2 56%).3 The certainty of evidence was downgraded one level for imprecision since each end of the confidence interval leads to a different decision.
