Department of Orthopaedics, Xuanwu Hospital, Capital Medical University, Beijing 100053, China.
Chin Med J (Engl). 2011 Jun;124(11):1653-6.
Total knee arthroplasty (TKA) is an important therapy for the treatment of various late-stage knee diseases. However, it has been observed that patients have lower hemoglobin (HB) counts postoperatively, which are significantly inconsistent with the measured blood loss. Although the concept of hidden blood loss has been presented in 2000, very little clinical attention has been paid since then. In this study, we investigated the characteristics and influential factor of hidden blood loss after TKA in treating knee osteoarthritis.
One hundred and eight patients, with 42 males and 66 females, were retrospectively analyzed. The perioperative blood loss and the hidden blood loss following TKA were calculated by Gross formula. Potential factors affecting perioperative and hidden blood loss included gender, surgical time, tourniquet time, hemostasis (during operation with deflating tourniquet), and reinfusion of salvaged blood.
The average perioperative blood loss was found to be (1553 ± 356) ml and the average hidden blood loss was (793 ± 223) ml. The hidden blood loss of the male was significantly higher than that of the female, and was reduced by hemostasis during the operation with a deflating tourniquet. Hidden blood loss was not affected by postoperative blood salvage and reinfusion, surgical time, or tourniquet time.
When calculating the value of hidden blood loss by Gross formula, the lowest value of hematocrit should be chosen as the parameter so that hidden blood loss would not be underestimated. No significant differences could be found in hidden blood loss for males compared to females. Hidden blood loss can be reduced by hemostasis during operation with a deflating tourniquet. Although reinfusion of salvaged blood could not reduce the perioperative blood loss or hidden blood loss, it was still an effective method to reduce transfusion rate.
全膝关节置换术（TKA）是治疗各种晚期膝关节疾病的重要疗法。然而，术后患者的血红蛋白（HB）计数较低，这与测量的失血量明显不一致。尽管 2000 年就提出了隐性失血的概念，但此后很少有临床关注。本研究旨在探讨 TKA 治疗膝骨关节炎隐性失血的特点及影响因素。
回顾性分析 108 例患者，男 42 例，女 66 例。采用 Gross 公式计算 TKA 围手术期失血量和隐性失血量。影响围手术期和隐性失血的潜在因素包括性别、手术时间、止血带时间、止血（带放气时）和回收血液的再输注。
平均围手术期失血量为（1553±356）ml，平均隐性失血量为（793±223）ml。男性隐性失血量明显高于女性，且带放气止血可减少隐性失血量。隐性失血不受术后血液回收和再输注、手术时间或止血带时间的影响。
用 Gross 公式计算隐性失血量时，应选择最低的红细胞压积值作为参数，以免低估隐性失血量。男性与女性的隐性失血量无显著差异。带放气止血可减少隐性失血。尽管回收血液不能减少围手术期失血量或隐性失血量，但它仍然是降低输血率的有效方法。
