Hidden blood loss in posterior lumbar interbodyfusion in patients with rheumatoid arthritis

English Keywords:Posterior lumbar interbody fusion  Rheumatoid arthritis  Hidden blood loss  Modified hidden blood loss

English Abstract:

  【Abstract】 Objectives: To evaluate the correlation between hidden blood loss(HBL) and the activity of rheumatoid arthritis(RA) in RA patients undergoing posterior lumbar interbody fusion(PLIF) or PLIF combined with posterior lateral fusion(PLF). Methods: This study retrospectively analyzed 61 patients (9 males and 52 females) with RA who underwent PLIF or PLIF plus PLF in our hospital from January 2012 to April 2018. The mean age was 66.0±8.0(y) and the mean duration of RA was 16.8±12.7(y) (0.4~60y). Data extraction include demographic information, RA related factorssuch as RA duration, anti-RA drugs and Steinbrocker classification as well as surgical levels, operation time and hemorrhage-related parameters such as pre- and post-operative hematocrit(Hct) and hemoglobin(Hb), intraoperative blood loss and postoperative drainage. HBL and mHBL were calculated using classical formula [Total blood loss(TBL)-(intraoperative blood loss)-(postoperative drainage)] and modified formula [TBL-(intraoperative blood loss)-drainage blood loss(DBL)] respectively, where TBL was calculated using Gross formula and patient blood volume(PBV) obtained gained using Nadler formula. ANOVA tests were used to compare TBL, HBL and mHBL in various-segment(1 segment, 2 segments and ≥ 3 segments) groups, as well as different grades of Steinbrocker classification, and to compare drainage, HBL and mHBL based on whether taking disease-modifying anti-rheumatic drugs (DMARDs) HBL, mHBL and their proportion in TBL were also compared. Results: There were 14 of grade Ⅰ, 34 of grade Ⅱ and 13 of grade Ⅲ by Steinbroker classification, of whom the most common anti-RA drugs was DMARDs(71.4%). The mean operation time and number of segments was 161.4±52.6min and 2.9±1.7 levels respectively. The mean TBL, intraoperative bleeding, drainage volume and DBL were 907.5±332.4ml, 454.4±386.7ml, 497.0±273.7ml and 300.6±178.3ml, respectively. Among different segments groups, there were statistical differences(P<0.05) in intraoperative blood loss, drainage and DBL but not in HBL and mHBL(P＞0.05). There was no significance in HBL and mHBL among various grades of Steinbroker classification(P＞0.05). DBL was lower in DMARDs group than that of non-drugged group(P<0.05), while HBL and mHBL was not significant different(P＞0.05). The comparison between HBL, mHBL(P<0.05) and their proportion of TBL(P<0.05) showed statistical difference, suggesting that mHBL volume was larger than HBL. Conclusions: There is no significant correlation between HBL and the activity of RA. That mHBL is larger than HBL provides a more accurate basis for measuring factual hidden blood loss and indicates the significance in noticing post-op drainage.