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The Bone & Joint Journal
Vol. 106-B, Issue 1 | Pages 93 - 98
1 Jan 2024
Broida SE Tsoi KM Rose PS Ferguson PC Griffin AM Wunder JS Houdek MT

Aims

The sacroiliac joint (SIJ) is the only mechanical connection between the axial skeleton and lower limbs. Following iliosacral resection, there is debate on whether reconstruction of the joint is necessary. There is a paucity of data comparing the outcomes of patients undergoing reconstruction and those who are not formally reconstructed.

Methods

A total of 60 patients (25 females, 35 males; mean age 39 years (SD 18)) undergoing iliosacral resection were reviewed. Most resections were performed for primary malignant tumours (n = 54; 90%). The mean follow-up for surviving patients was nine years (2 to 19).


Bone & Joint Open
Vol. 4, Issue 6 | Pages 399 - 407
1 Jun 2023
Yeramosu T Ahmad W Satpathy J Farrar JM Golladay GJ Patel NK

Aims

To identify variables independently associated with same-day discharge (SDD) of patients following revision total knee arthroplasty (rTKA) and to develop machine learning algorithms to predict suitable candidates for outpatient rTKA.

Methods

Data were obtained from the American College of Surgeons National Quality Improvement Programme (ACS-NSQIP) database from the years 2018 to 2020. Patients with elective, unilateral rTKA procedures and a total hospital length of stay between zero and four days were included. Demographic, preoperative, and intraoperative variables were analyzed. A multivariable logistic regression (MLR) model and various machine learning techniques were compared using area under the curve (AUC), calibration, and decision curve analysis. Important and significant variables were identified from the models.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_13 | Pages 41 - 41
1 Dec 2022
Koucheki R Howard AW McVey M Levin D McDonnell C Lebel D
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This study aimed to identify factors associated with increased rates of blood transfusion in patients with adolescent idiopathic scoliosis (AIS) treated with posterior spinal fusion (PSF). A retrospective case-control study was performed for AIS patients treated at a large children's hospital between August 2018 and December 2020. All patients with a diagnosis of AIS were evaluated. Data on patient demographics, AIS, and transfusion parameters were collected. Univariate regression and multivariate logistic modeling were utilized to assess risk factors associated with requiring transfusion. Odds ratios (OR) and 95% confidence interval (CI) were calculated. Surgeries were done by three surgeons and thirty anesthesiologists. To quantify the influence of anesthesia practice preferences a categorical variable was defined as “higher-transfusion practice preference”, for the provider with the highest rate of transfusion. A total of 157 AIS patients were included, of whom 56 were transfused RBC units (cases), and 101 did not receive any RBC transfusion (controls). On univariate analysis, the following variables were significantly correlated with receiving RBC transfusion: “higher-transfusion practice preference,” “administration of crystalloids,” “receiving fresh frozen plasma (FFP),” “receiving platelets,” “pre-operative hemoglobin,” “cell saver volume,” and “surgical time.” On multiple regression modeling, “pre-operative hemoglobin less than 120 g/L” (OR 14.05, 95% CI: 1.951 to 135.7) and “higher-transfusion practice preference” (OR 11.84, 95% CI: 2.505 to 63.65) were found to be meaningfully and significantly predictive of RBC transfusion. In this cohort, we identified pre-operative hemoglobin of 120 g/L as a critical threshold for requiring transfusion. In addition, we identified significant contribution from anesthesia transfusion practice preferences. Our multivariate model indicated that these two factors are the major significant contributors to allogenic blood transfusion. Although further studies are required to better understand factors contributing to transfusion in AIS patients, we suggest standardized, peri-operative evidence-based strategies to potentially help reduce variations due to individual provider preferences


The Bone & Joint Journal
Vol. 104-B, Issue 11 | Pages 1266 - 1272
1 Nov 2022
Farrow L Brasnic L Martin C Ward K Adam K Hall AJ Clement ND MacLullich AMJ

Aims

The aim of this study was to examine perioperative blood transfusion practice, and associations with clinical outcomes, in a national cohort of hip fracture patients.

Methods

A retrospective cohort study was undertaken using linked data from the Scottish Hip Fracture Audit and the Scottish National Blood Transfusion Service between May 2016 and December 2020. All patients aged ≥ 50 years admitted to a Scottish hospital with a hip fracture were included. Assessment of the factors independently associated with red blood cell transfusion (RBCT) during admission was performed, alongside determination of the association between RBCT and hip fracture outcomes.


Bone & Joint Open
Vol. 2, Issue 10 | Pages 850 - 857
19 Oct 2021
Blankstein AR Houston BL Fergusson DA Houston DS Rimmer E Bohm E Aziz M Garland A Doucette S Balshaw R Turgeon A Zarychanski R

Aims. Orthopaedic surgeries are complex, frequently performed procedures associated with significant haemorrhage and perioperative blood transfusion. Given refinements in surgical techniques and changes to transfusion practices, we aim to describe contemporary transfusion practices in orthopaedic surgery in order to inform perioperative planning and blood banking requirements. Methods. We performed a retrospective cohort study of adult patients who underwent orthopaedic surgery at four Canadian hospitals between 2014 and 2016. We studied all patients admitted to hospital for nonarthroscopic joint surgeries, amputations, and fracture surgeries. For each surgery and surgical subgroup, we characterized the proportion of patients who received red blood cell (RBC) transfusion, the mean/median number of RBC units transfused, and exposure to platelets and plasma. Results. Of the 14,584 included patients, the most commonly performed surgeries were knee arthroplasty (24.8%), hip arthroplasty (24.6%), and hip fracture surgery (17.4%). A total of 10.3% of patients received RBC transfusion; the proportion of patients receiving RBC transfusions varied widely based on the surgical subgroup (0.0% to 33.1%). Primary knee arthroplasty and hip arthroplasty, the two most common surgeries, were associated with in-hospital transfusion frequencies of 2.8% and 4.5%, respectively. RBC transfusion occurred in 25.0% of hip fracture surgeries, accounting for the greatest total number of RBC units transfused in our cohort (38.0% of all transfused RBC units). Platelet and plasma transfusions were uncommon. Conclusion. Orthopaedic surgeries were associated with variable rates of transfusion. The rate of RBC transfusion is highly dependent on the surgery type. Identifying surgeries with the highest transfusion rates, and further evaluation of factors that contribute to transfusion in identified at-risk populations, can serve to inform perioperative planning and blood bank requirements, and facilitate pre-emptive transfusion mitigation strategies. Cite this article: Bone Jt Open 2021;2(10):850–857


The Bone & Joint Journal
Vol. 103-B, Issue 3 | Pages 440 - 441
1 Mar 2021
Nikolaou VS Masouros P Floros T Chronopoulos E Skertsou M Babis GC


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_2 | Pages 89 - 89
1 Mar 2021
Assaf A Hermena S Hadjikyriacou E Donaldson O
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Abstract. Objectives. Routine blood test following total shoulder arthroplasty (TSA) cost the NHS more than £72000 in 2018 without definite evidence of their impact on patients’ management or outcomes. This study aimed to ascertain if routine laboratory tests are a necessity post TSA or can be implemented on a per-patient. Methods. A retrospective review of the electronic records completed for 251 patients underwent TSA over 6 years. 193 patients were eligible for analysis. Primary outcomes were interventions to the abnormal postoperative blood tests. Secondary outcomes were the length of stay (LOS), and readmission within 30 days and 90 days. Results. 193 patients underwent 216 TSAs; 72 % were females and 18% males. The mean age was 78 ± 7.2 years. Completed procedures included 134 reverse, 64 anatomical and 18 revision TSAs. 136 patients (63%) had an abnormal postoperative blood test, however, only 8 (3.7%) required intervention. The average postoperative haemoglobin (Hb) drop was 19 g/L with 94 patients (43.5%) having Hb <109g/L. 4 patients (1.8%) dropped Hb < 80g/L; only 2 patients (0.9%) were symptomatic and received RBC transfusion . 6 patients (2.8%) developed acute kidney injury and treated by IV fluids. The mean LOS was 3.2 ± 2.9 days .5 patients (2.3%) were readmitted within 30 days and 6 patients (2.8%) within 90 days. Univariate analysis showed association only between abnormal Creatinine and LOS (p<0.05) and of these patients, all had abnormal preoperative Creatinine baseline. No statistical correlation detected between age (p=0.287), postoperative Hb (p=0.230) and LOS nor readmission at 30 or 90 days. Conclusions. Routine postoperative blood tests are not required as they have not shown to produce a meaningful clinical impact in this cohort of patients nor on the re-admission rate, causing unnecessary costs. We recommend assessing each patient and request for investigations in a coherent and justified manner. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_11 | Pages 101 - 101
1 Dec 2020
Assaf A Hermena S Hadjikyriacou E Donaldson O
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Introduction. Postoperative total shoulder arthroplasty (TSA) blood tests cost the National Health Service in the UK more than £72000 annually without definite evidence of their impact on outcomes. This study aimed to ascertain if these blood tests can be implemented on a per-patient basis. Methods. A retrospective review of one centre TSA patients over 6 years. Primary outcomes were interventions to abnormal postoperative blood tests. Secondary outcomes were the length of stay (LOS), and readmission within 30 and 90 days. Results. 193 patients underwent 216 TSAs; 72 % were females and 18% males. The mean age was 78 ± 7.2 years. Completed procedures included 134 reverse, 64 anatomical and 18 revision TSAs. 136 patients (63%) had an abnormal postoperative blood test, however, only 8 (3.7%) required intervention. The average postoperative Hb drop was 19 g/L with 94 patients (43.5%) having Hb <109g/L. 4 patients (1.8%) dropped Hb < 80g/L; only 2 (0.9%) were symptomatic and received RBC transfusion. 6 patients (2.8%) developed acute kidney injury and treated by IV fluids. The mean LOS was 3.2 ± 2.9 days .5 patients (2.3%) were readmitted within 30 days and 6 patients (2.8%) within 90 days. Univariate analysis showed association only between abnormal Creatinine and LOS (p<0.05) and of these patients, all had abnormal preoperative Creatinine baseline. No statistical correlation detected between age (p=0.287), postoperative Hb (p=0.230) and LOS nor readmission at 30 or 90 days. Conclusions. Routine postoperative blood tests are not required as no detected meaningful clinical impact and should be requested on an individual justified basis


The Bone & Joint Journal
Vol. 101-B, Issue 9 | Pages 1122 - 1128
1 Sep 2019
Yombi JC Putineanu DC Cornu O Lavand’homme P Cornette P Castanares-Zapatero D

Aims. Low haemoglobin (Hb) at admission has been identified as a risk factor for mortality for elderly patients with hip fractures in some studies. However, this remains controversial. This study aims to analyze the association between Hb level at admission and mortality in elderly patients with hip fracture undergoing surgery. Patients and Methods. All consecutive patients (prospective database) admitted with hip fracture operated in a tertiary hospital between 2012 and 2016 were analyzed. We collected patient characteristics, time to surgery, duration and type of surgery, comorbidities, Hb at admission, nadir of Hb after surgery, the use and amount of red blood cells (RBCs) transfusion products, postoperative complications, and death. The main outcome measures were mortality at 30 days, 90 days, 180 days, and one year after surgery. Results. We included 829 patients; the mean age was 81 years (. sd. 11). Mortality at 30 days, 90 days, 180 days, and one year was 5.7%, 12.3%, 18.1%, and 23.5%, respectively. The highest mortality was observed in patients aged over 80 years (162/557, 29%) and in male patients (85/267, 32%). Survival at 90 days, 180 days, and one year after surgery was significantly lower in patients with a Hb level below 120 g/l at admission. In multivariate analysis, Hb level below 120 g/l at admission was found to be an independent factor associated with mortality (adjusted hazard ratio (aHR) 1.68 (95% confidence interval (CI) 1.22 to 2.31); p = 0.001), along with age (aHR 1.06 (95% CI 1.04 to 1.06); p < 0.001), male sex (aHR 2.19 (95% CI 1.61 to 2.96); p < 0.001), and need for RBC transfusions (aHR 1.10 (95% CI 1.02 to 1.19); p = 0.01). Conclusion. Our results suggest that low Hb at admission along with age and RBC transfusions is significantly associated with short- and long-term mortality after hip fracture surgery, independently of comorbidity confounders. Further studies should be performed to understand how preoperative Hb could be taken into account in perioperative management. Cite this article: Bone Joint J 2019;101-B:1122–1128


The Bone & Joint Journal
Vol. 101-B, Issue 9 | Pages 1093 - 1099
1 Sep 2019
Bradley KE Ryan SP Penrose CT Grant SA Wellman SS Attarian DE Green CL Risoli T Bolognesi MP

Aims

Antifibrinolytic agents, including tranexamic acid (TXA) and epsilon-aminocaproic acid (EACA), have been shown to be safe and effective for decreasing perioperative blood loss and transfusion following total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, there are few prospective studies that directly compare these agents. The purpose of this study was to compare the benefits of intraoperative intravenous TXA with EACA.

Patients and Methods

A total of 235 patients (90 THA and 145 TKA) were enrolled in this prospective, randomized controlled trial at a single tertiary-care referral centre. In the THA cohort, 53.3% of the patients were female with a median age of 59.8 years (interquartile range (IQR) 53.3 to 68.1). In the TKA cohort, 63.4% of the patients were female with a median age of 65.1 years (IQR 59.4 to 69.5). Patients received either TXA (n = 119) or EACA (n = 116) in two doses intraoperatively. The primary outcome measures included change in haemoglobin level and blood volume, postoperative drainage, and rate of transfusion. Secondary outcome measures included postoperative complications, cost, and length of stay (LOS).


Orthopaedic Proceedings
Vol. 97-B, Issue SUPP_15 | Pages 34 - 34
1 Dec 2015
Tornero E Pereira A Morata L Angulo S García-Velez D García-Ramiro S Soriano A
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Stored red blood cells (RBCs) undergo a variety of changes that impair their post-transfusion viability, but the detrimental effect of such lesion at the clinical level is a matter of debate (1) and there is no data about the incidence of postoperative infection, a complication frequently associated with transfusion of stored RBCs (2). We reviewed 9906 patients who underwent a primary or revision arthroplasty between January 2000 and December 2012. Of these, 1153 (11.6%) received transfusion during surgery or within the first 6h after surgery (early transfusion, ET) and 920 (9.3%) received transfusion only between 24 and 96 hours after surgery (late transfusion, LT). Primary end-point was prosthetic joint infection (PJI) within the first year. Demographics, joint, type of surgery, duration of surgery, number and length of storage of transfused RBCs were collected. Ethical Committee approved the study. The median age was 74.9 (IQR:68.3–80.1) years and 1546 (74.6%) were female. There were 914 (44.1%) hip and 1117 (53.9%) knee arthroplasties and 428 (20.6%) were revision surgeries. The median duration of surgery was 105 (IQR:80–145) minutes. A total of 100 (4.8%) patients had a PJI. Figure 1 shows the PJI rate according to the number of RBC units transfused and the proportion of such units that had been stored for more than 14 days, both in the ET-group (Fig. 1A) and the LT-group (Fig. 1B). In the ET-group, the fact that >50% of transfused RBCs had been stored >14 days was an independent predictor of PJI (OR:2.50, 95%CI:1.44–4.33, Hosmer-Lemeshow test P=0.972). Stored RBC occlude the microcirculation (1), thereby precluding a good oxygenation of the surgical wound and the arrival of leukocytes and prophylactic antibiotics. Both factors are involved in the progression from wound bacterial contamination to wound infection and are particularly operative in the few hours following surgery (5). It is biologically plausible that transfusion of old RBC in this early, critical period results in more wound infections as compared to RBCs transfused later


The Bone & Joint Journal
Vol. 96-B, Issue 9 | Pages 1143 - 1154
1 Sep 2014
Mauffrey C Cuellar III DO Pieracci F Hak DJ Hammerberg EM Stahel PF Burlew CC Moore EE

Exsanguination is the second most common cause of death in patients who suffer severe trauma. The management of haemodynamically unstable high-energy pelvic injuries remains controversial, as there are no universally accepted guidelines to direct surgeons on the ideal use of pelvic packing or early angio-embolisation. Additionally, the optimal resuscitation strategy, which prevents or halts the progression of the trauma-induced coagulopathy, remains unknown. Although early and aggressive use of blood products in these patients appears to improve survival, over-enthusiastic resuscitative measures may not be the safest strategy.

This paper provides an overview of the classification of pelvic injuries and the current evidence on best-practice management of high-energy pelvic fractures, including resuscitation, transfusion of blood components, monitoring of coagulopathy, and procedural interventions including pre-peritoneal pelvic packing, external fixation and angiographic embolisation.

Cite this article: Bone Joint J 2014; 96-B:1143–54.


The Bone & Joint Journal
Vol. 95-B, Issue 11_Supple_A | Pages 135 - 139
1 Nov 2013
Reinhardt KR Osoria H Nam D Alexiades MA Figgie MP Su EP

Blood loss during total knee replacement (TKR) remains a significant concern. In this study, 114 patients underwent TKR, and were divided into two groups based on whether they received a new generation fibrin sealant intra-operatively, or a local infiltration containing adrenaline. Groups were then compared for mean calculated total blood volume (TBV) loss, transfusion rates, and knee range of movement. Mean TBV loss was similar between groups: fibrin sealant mean was 705 ml (281 to 1744), local adrenaline mean was 712 ml (261 to 2308) (p = 0.929). Overall, significantly fewer units of blood were transfused in the fibrin sealant group (seven units) compared with the local adrenaline group (15 units) (p = 0.0479). Per patient transfused, significantly fewer units of blood were transfused in the fibrin sealant group (1.0 units) compared with the local adrenaline group (1.67 units) (p = 0.027), suggesting that the fibrin sealant may reduce the need for multiple unit transfusions. Knee range of movement was similar between groups. From our results, it appears that application of this newer fibrin sealant results in blood loss and transfusion rates that are low and similar to previously applied fibrin sealants.

Cite this article: Bone Joint J 2013;95-B, Supple A:135–9.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_IV | Pages 495 - 495
1 Oct 2010
Dettoni F Castoldi F Collo G Lollino N Marmotti A Parisi S Rossi R
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Aim: Evaluate the incidence of complications related to timing (time between admission ad operation) and oral antiplatelet/anticoagulant therapy in patients treated for a hip fracture. Materials and Methods: We prospectively evaluated 5 groups of 30 patients each, selected out of 875 consecutive patients admitted at the First Aid Unit of our Hospital with a proximal femoral fracture: group A – patients on Warfarin therapy, treated more than 5 days after admission (in order to allow the wash-out of Warfarin, as advised by many Anaesthesiologist Associations); B – patients treated more than 5 days after admission, not on Warfarin therapy; C – patients treated less than 48 hours after admission, not on Warfarin therapy; D – patients on Aspirin/NSAIDS therapy, treated more than 5 days after admission; E – patients on Ticlopidine/Clopidogrel therapy, treated more than 5 days after admission. The groups were comparable regarding age, gender, pre-trauma walking ability, mental state, fracture type and treatment. Blood loss, number of RBC transfusions, complications during hospitalization and up to 6 months after discharge, duration of hospitalization, degree of functional recovery and 2 years mortality were recorded. Statistical analysis included Kruskall-Wallis, U-Mann-Whitney and Logistic Regression Tests (SPSS 13.0 software). Results: Group A showed higher preoperative blood loss (p=0.002), and longer hospitalization (p< 0.001), compared to all other groups. Groups D and E showed no higher complication and mortality rate in comparison to group B and C, while group A showed higher complication and mortality rate. Standing alone, timing and Warfarin appear not to be significant risk factors, while taken together they represent a high risk factor for complications ad mortality (p=0.009). Conclusion: Patients on Warfarin therapy, affected by hip fracture, are at high risk of complications and mortality, if the recommendation of postponing treatment until drug wash-out is accepted. Reversal of anticoagulation using vitamin K and straight-forward treatment should be considered. Antiplatelet therapy appears not to have the same adverse effect as anticoagulant therapy


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_II | Pages 272 - 273
1 May 2010
Kim KI Cho YJ Chun YS Rhyu KH Yoo MC
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Introduction: The aim of this study is to analyze the mid-term result of cementless total hip arthroplasty(THA) performed in hemophilic arthropathy of the hip. Materials and Methods: Of the 22 hips (19 patients) that underwent cementless THA under the diagnosis of hemophilic arthropathy from Aug. 1995 to June. 2002, 20 hips (17 patients) that can be followed more than five years were enrolled. The average age was 35.1 years. All of the patients had type A hemophilia. There was no patient who had antibody for factors or positive test for HIV. The mean follow-up period was 99.6 (61–147) months. As a clinical assessment, we evaluated Harris hip score, hip range of motion, amount of transfusion and factor replacement, perioperative bleeding and the problems associated with the use of coagulation factors and the bleeding itself after the surgery. As a radiological assessment, we evaluated the stability and fixation of the components, various bone responses around the implants and complications such as loosening and osteolysis. Results: The average Harris hip score improved from 62.4 before surgery to 93.6 at the final follow-up. The hip range of motions in all plane significantly increased after the operation. During and after the surgery, an average of 3.2 units of packed RBC was transfused and an average of 46000 units of coagulation factors was injected. All patient obtained significant pain relief and improvement walking ability after the operation. The episode of re-bleeding was observed in four cases. In one of them, severe osteolysis around the pelvis and femoral stem was noted due to a huge pseudotumor. Radiographically, all components except one cup showed stable fixation at the final follow-up. The osteolysis was noted in three cups and three stems each. As a re-operation, one morsellized bone graft for osteolysis and one cup revision for a loosened cup were performed at 134 and 40 months after the index operation. One case of pseudotumor is waiting for the surgery. Conclusion: Unlike the worrisome results of cemented THA, meticulously performed cementless THA for the moderate or severe hemophilic arthropathy is safe and greatly effective in reducing the pain, increasing the range of hip motion and improving the walking ability. However, special attention should be paid to the possible complications associated with re-bleeding such as pseudotumor around the hip. To obtain best result multidisciplinary team approach is mandatory


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_II | Pages 165 - 165
1 Feb 2004
Barbarousi D Dermon A Muratidou Ì Petrou H Lilis D Skitiotis D Pagonis S Petrou G
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In modern surgery, one main goal is to reduce perioperative and postoperative transfusion need. The haemostatic disorders, the patients’ gender and the type of the operation seems to predict the blood loss in orthopaedic surgery. It has been reported recently, an association of the Factor V Leiden mutation and with a lower rate of intra-partum blood loss,. Purpose: The aim of our study was to evaluate if there is an association between blood loss and pro c global system in orthopaedic operations. Pro C Global system is influenced by FRO C, PRO S, APC resistance (FV Leiden) and FV111. Materials and methods: We studied 42 patients, 31 women and 11 men, between 22–86 years old, who were operated in our hospital. 19 with total knee arthroplasty, 11 with total hip arthroplasty, 11 with fractures and 1 patient with amputation of -the lower leg. The blood loss for each patient was calculated according the Mercurialli formula: Total blood loss: total blood volume x (Ht preop-Ht day 5 postop)+ml of RBC transfused. The total blood loss was expressed in terms of percentage of total blood volume and defined as relative blood loss. Patients were divided into two groups with high and low relative blood loss, according the median value of the relative blood loss. Pro C global values was monitored in all patients pre-operatively on a BCT analyzer (Dade Behring). Values > 0.8 are considered normal. Results: The median value of relative blood loss was 15,05%. 21 patients were below this level and considered to have low relative blood loss. 21 patients were above this level and considered to have high relative blood loss. 18 patients had pro C Global values < 0.8 and 24 patients had Pro C Global > 0.8. Patients with low relative blood loss tend to show lower Pro C Global values than patients with high relative blood loss. (0,87 versus 0.90, p= 0.7 NS) without statistical difference. Conclusions: In this study the Pro C global system does not seems to predict perioperative blood loss in patients with orthopaedic surgery and so it is useless to be monitored preoperatively


Orthopaedic Proceedings
Vol. 85-B, Issue SUPP_I | Pages 36 - 36
1 Jan 2003
Sehat K Evans R Newman J
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In Total Knee Arthroplasty (TKA) and Total Hip Arthroplasty (THA) the total blood loss is composed of ‘visible’ blood loss from the surgical field and wound drainage, and blood loss into the tissues which is ‘hidden’. Blood management should be aimed at addressing the total blood loss. 56 TKAs and 46 THAs were prospectively studied. TKAs were performed with tourniquet. After tourniquet release, all drained blood was salvaged and significant volumes reinfused. No reinfusion was used for THAs. The true total blood loss was calculated in the following way:. Patient Blood Volume (PBV) is: [1]. PBV = k1 x height3 + k2 x weight + k3. Therefore patient total Red Blood Cell volume (RBCv) is:. RBCv = PBV x Hct. (where Hct is Haematocrit). Total RBCv loss = PBV x (Hct preop – Hct postop) + ml RBC transfused. The result is reconverted to Whole Blood volume. Hidden Loss = Total Loss – Visible Loss. In TKA, the mean total true blood loss was 1474ml. The mean hidden loss was 735ml. Therefore hidden loss is 50% of the total loss and the total true loss following TKA is twice the visible volume. In THA, the mean total true blood loss was 1629ml. The mean hidden loss was 343ml. Thus hidden loss in THA is much smaller. (21%) Total loss is 1.3 times the visible loss. In the TKA group, comparing patients with large losses receiving reinfusion and those with small losses not receiving reinfusion, the proportion of total true loss which was hidden was the same, at 50%. Patients with Body Mass Index (BMI) > 30 were compared with those with a BMI < 30 and no correlation was found between BMI and Hidden Loss. Joint Replacement Surgery involves a ‘hidden’ blood loss which is not revealed and cannot be measured or reinfused in practice, but which should be taken into account when planning blood loss management. In TKA it is substantial. In THA it is much smaller and probably not of as much clinical concern. Hidden loss is no greater in the Obese patient