Total Knee Arthroplasty Hidden Blood Loss And Risk Factors

Objective:To Study the correlated mechanisms and the risk factors that affect perioperative hidden blood loss of total knee arthroplasty and clarify the mechanisms by computing the peri-operative blood loss and analysing the risk factors,on the purpose of evaluating the surgical risk.Methods:From September 2007 to September 2008,136 patients involved 192 knees were treated with TKA,including 80 unilateral TKAs and 56 bilateral TKAs.The average age of the patients was 67.5 years.All TKAs were managed by the same surgery groups,which the 24h fluid resuscitation was less than 2000ml.Gross formula,the true total blood loss was calculated depending on height,weight and pre-and post-operation Hct,and the hidden hemorhage was got by subtracting the visible blood loss from total loss.We noted the risk factors such as age,sex,BMI,and transfusion to conclude the difference between hidden blood loss and each risk factor group with statistic analysis using SPSS 10.0 software.Result: The average volume of total perioperative blood loss of unibilateral TKA was 1650ml,while the volume of hidden blood loss was 830ml;the average volume of total perioperative blood loss of unilateral TKA was 2864ml,while the volume of hidden blood loss was 1487ml.There was no significant difference between age and blood loss.The volume of hidden blood loss had statistical differences between male and female.The percentage of hidden blood loss of bilateral TKA was larger.Autologous-transfusion can increase the perioperative hidden blood loss volume of TKA,no matter bilateral or unilateral.The blood loss of obese and old patients was significangtly more than the control group.Conclusion:The pefioperative blood loss volume of TKA is large,while the percentage of hidden blood loss is more than 50%.Male,elder,bilateral operation and autologous transfusion are the risk factors that can increase the volume of perioperative blood loss.