Analysis of the estimation of bleeding using several proposed haematometric equations.

PURPOSE: Among various methods for estimating blood loss, the gravimetric method is the most accurate; however, its use in routine practice is complicated. Although several equations have been proposed for this purpose, there is no consensus on the most suitable. METHODS: A cross-sectional study was conducted in seven secondary and tertiary hospitals between March and July 2018 including all patients undergoing total hip arthroplasty or hip prosthesis replacement under general or regional anaesthesia. We compared blood loss estimates obtained using the gravimetric method (weighing gauzes and pads and measuring volumes of blood collected by suction during surgery) and using three different equations, two of which considered intravenous fluids (CRYS 3.5 and 1.5) and a third which did not (the traditional equation). Additionally, intraclass correlation coefficients (ICCs) and Bland-Altman plots were used. RESULTS: The mean blood loss estimated using the gravimetric method was 513.7 ± 421.7 mL, while estimates calculated using the CRYS 3.5, CRYS 1.5 and traditional equations were 737.2 ± 627.4, 420.8 ± 636.2 and 603.4 ± 386.3 mL, respectively. Comparing these results, we found low levels of agreement (based on ICCs), except when using the traditional equation (ICC: 0.517). The limits of agreement comparing external blood loss with the estimates from the equations ranged from - 1655.6 to 1459.2 in the case of the CRYS 1.5 equation to - 839.6 to 1008.4 in the case of the traditional equation. CONCLUSIONS: For use in clinical practice, haematological index-based equations, regardless of whether they consider fluids administered, do not show sufficiently strong correlations with gravimetric estimates of intraoperative blood loss.

Cost-benefit analysis of the use of tranexamic acid in total replacement hip surgery.

STUDY OBJECTIVE: To establish the best dose regimen for tranexamic acid (TXA) in total hip replacement surgery. DESIGN: Secondary analysis based on data from a multicenter double-blind randomized clinical trial. SETTING: Two hospitals in Spain. INTERVENTIONS: TXA (2 doses) versus placebo. PATIENTS: Consecutive adults who underwent uncemented unilateral total replacement hip surgery. MEASUREMENTS: We estimated the costs associated with TXA use (including consumables, drugs and nurse time) and allogeneic and autologous blood transfusions. For the cost-benefit analysis, we considered the spending on controls to estimate the benefits and the spending on patients in the intervention arms to estimate the costs. The net cost-benefit of TXA administration was calculated by subtracting the costs incurred per patient given TXA from the costs per patient given placebo. MAIN RESULTS: The median total costs per patient were €2.7 (2.4-3.0) in the single-dose group, €6.5 (6.5-7.1) in the two-dose group and €0 (0-190) in the control group (p = 0.001). The blood transfusion costs were €1607.8, €1041.8 and €3115.3 in the single-dose, two-dose and control groups, respectively. The administration of two doses of TXA achieved a greater net cost-benefit than a single dose, the difference being €566 in terms of overall costs. CONCLUSIONS: The administration of TXA is cost-effective, especially in the case of the two-dose regimen studied.

Determination of Perioperative Blood Loss: Accuracy or Approximation?

BACKGROUND: Various different interventions can be used to reduce surgical blood loss; however, there is no "gold standard" for accurately measuring the volume of perioperative blood loss, and this makes it difficult to assess the efficacy of these interventions. METHODS: We used data from a previous multicenter double-blind randomized clinical trial in patients undergoing total hip arthroplasty in which we compared 2 regimens for administering tranexamic acid versus placebo. We assessed direct measures (external blood loss) and indirect estimates (using the formulas of Bourke, Gross, Mercuriali, and Camarasa and a new formula we have developed) using analysis of variance to compare estimated volumes of blood loss among the study groups. In addition, intraclass correlation coefficients (ICCs) and Bland-Altman diagrams were used to compare the estimated volumes of blood loss obtained with each formula. RESULTS: The mean estimated external blood loss was 909 ± 324 mL, and the mean estimates of blood loss calculated using the formulas of Gross, Bourke and Smith, and Camarasa were 1308 ± 555, 1091 ± 454, and 1641 ± 945 mL, respectively, whereas we obtained a value of 1511 ± 919 mL with the new formula at day 2. In all cases, the results favored the use of tranexamic acid (P < .0001). Comparing results of the new and other formulas, we found moderate-to-low agreement (in terms of ICCs) except for that of Camarasa (ICC: 0.992). The limits of agreement with the new formula ranged from -378 to 93 in the case of the comparison with Camarasa's formula and from -2226 to 959 for external blood loss, the difference depending on the magnitude of the estimate to a large extent. CONCLUSIONS: Formulas that take into account both anthropometric and laboratory parameters are useful for evaluating the efficacy of interventions aiming to decrease blood loss but do not ensure that the values obtained are sufficiently accurate for absolute measuring.

Assessment of a smartphone app (Capstesia) for measuring pulse pressure variation: agreement between two methods: A Cross-sectional study.

BACKGROUND: Less invasive and noninvasive methods are emerging for haemodynamic monitoring. Among them is Capstesia, a smartphone app that, from photographs of a patient monitor showing invasive arterial pressure, estimates advanced haemodynamic variables after digitising and analysing the pressure curves. OBJECTIVE: The aim of this study was to compare the level of agreement between the analysis of the signals obtained from the patient monitor and a photograph of the same images using the Capstesia app. DESIGN: Cross-sectional study. SETTING: Araba University hospital (Txagorritxu), Vitoria-Gasteiz, Alava, Spain, from January to February 2015. PATIENTS: Twenty patients (229 images) who had an arterial catheter (radial or femoral artery) inserted for haemodynamic monitoring. INTERVENTION: Snapshots obtained from the patient monitor and a photograph of these same snapshots using the Capstesia application were assessed with the same software (MATLAB, Mathworks, Natick, Massachusetats, USA) for evaluating the level of concordance of the following variables: pulse pressure variation (PPV), cardiac output (CO) and maximum slope of the pressure curve (dP/dt). Comparison was made using interclass correlation coefficients with corresponding 95% confidence intervals, and Bland-Altman plots with the corresponding percentages of error. MAIN OUTCOME MEASURES: (PPV). Secondary outcome: CO and maximum slope of the pressure curve [dP/dt]. RESULTS: The interclass correlation coefficients for PPV, CO and max dP/dt were 0.991 (95% confidence interval 0.988 to 0.993), 0.966 (95% confidence interval 0.956 to 0.974) and 0.962 (95% confidence interval 0.950 to 0.970), respectively. In the Bland-Altman analysis, bias and limits of agreement of PPV were (0.50% ±â€Š1.42) resulting in a percentage of error of 20% for PPV. For CO they were 0.19 ±â€Š0.341, with a 13.8% of error. Finally bias and limits of agreement for max dP/dt were 1.33 ±â€Š77.71, resulting in an error of 14.20% CONCLUSIONS: Photograph of the screenshots obtained with the Capstesia app show a good concordance with analysis of the original screenshots. Either approach could be used to monitor the haemodynamic variables assessed.

Tranexamic Acid Compared with Placebo for Reducing Total Blood Loss in Hip Replacement Surgery: A Randomized Clinical Trial.

BACKGROUND: Tranexamic acid (TXA) reduces bleeding in patients undergoing hip replacement surgery, but optimal doses and timing have yet to be established. Our primary objective in this study was to assess total blood loss 48 hours after surgery with different regimens. METHODS: This was a multicenter, parallel-group, randomized, placebo-controlled clinical trial that included all ASA physical status I to III patients undergoing unilateral total hip replacement surgery who met the inclusion criteria. Patients were randomly allocated to 1 of 3 groups: a single-dose group (15 mg/kg TXA before the start of surgery and saline 3 hours later after the start of surgery), a 2-dose group (10 m/kg TXA before and 10 mg/kg of TXA 3 hours after the start of surgery), and a control group (saline before and 3 hours after the start of surgery). Total blood loss was calculated using a formula considering hematocrit values and blood transfusions received. RESULTS: We included 108 patients in the study. Total blood loss volumes up to day 2 were 1377 ± 689, 1308 ± 641, and 2215 ± 1136 mL in the single-dose, 2-dose and control groups, respectively (P < 0.001 between the placebo and the experimental groups). Blood transfusions were given to 22.9% of patients (n = 8) in the single-dose group, 11.1% (n = 4) in the 2-dose group, and 37.8% (n = 14) in the control group (P = 0.028). CONCLUSIONS: A single preoperative dose of TXA or 2 infusions of a lower dose, preoperatively and then after 3 hours after the start of surgery, resulted in lower blood loss during the first 2 days after surgery and less need for blood transfusion, with good levels of safety.