Bleeding in Knee Arthroplasty After Preconditioning With Sevoflurane
Status:
Completed
Trial end date:
2020-12-19
Target enrollment:
Participant gender:
Summary
Knee arthroplasty is performed with restriction of blood flow by use of the pressure
tourniquet. Ischemia of skeletal musculature is accompanied by the formation of reactive
oxygen species and release of vasoactive factors. Inhaled anesthetics were described as
possible protective factors, termed "ischemic preconditioning". The objective of this
investigation is to observe the effects of preconditioning with inhaled anesthetic on
bleeding in the postoperative period of knee arthroplasty surgery. The study will be
prospective and randomized. Patients will be allocated by means of a randomized table in two
groups: Group Preconditioning (GP) - subarachnoid and general anesthesia with preconditioning
with 1 minimal alveolar concentration (MAC) for 15 minutes before the installation of the
ischemia by tourniquet; Group control (GC) - subarachnoid and general anesthesia with
sevoflurane without preconditioning. Will be evaluated: hemoglobin and hematocrit, platelet
count and coagulogram, electrolytes and creatinine, lactate and glycemia. Volume of drainage
will be evaluated until drainage is withdrawn and need for transfusion measuring the number
of bags of blood concentrate and volume transfused. Pain assessment will be done by means of
visual analog scale. Morbidity will be recorded up to the 30th postoperative day by chart
analysis. Patients will be allocated to the study groups by random number table. Data will be
presented descriptively, frequently, mean and standard deviation, or medians and distribution
in 25-75% percentiles. The comparison between continuous measurements will be made by means
of repeated measures intra-group analysis of variance (ANOVA) and Student's t-test for
evaluation between groups. The need for transfusion will be compared by Fisher's exact test.
Pain intensity will be compared by Wilcoxon test for non-parametric data. A commercially
available statistical package - SPSS version 15.0 (SPSS Inc.) will be used. A value of P
<0.05 will be considered statistically significant.