Intra-operative blood salvage in total hip and knee arthroplasty

Purpose To review records of 371 patients who underwent total hip or knee arthroplasty (THA or TKA) with intra-operative blood salvage to determine the allogeneic blood transfusion rate and the predictors for allogeneic blood transfusion. Methods Records of 155 male and 216 female consecutive patients aged 17 to 95 (mean, 70) years who underwent primary THA or TKA by a single surgeon with the use of intra-operative blood salvage were reviewed. Results The preoperative haemoglobin level was &lt;120 g/dl in 15% of THA patients and 5% of TKA patients; the allogeneic transfusion rate was 24% in THA patients and 12% in TKA patients. Despite routine use of intra-operative blood salvage, only 59% of THA patients and 63% of TKA patients actually received salvaged blood, as a minimum of 200 ml blood loss was required to activate blood salvage. In multivariable analysis, predictors for allogeneic blood transfusion were female gender (adjusted odds ratio [OR]=2.8, p=0.02), age &gt;75 years (adjusted OR=5.9, p&lt;0.001), and preoperative haemoglobin level &lt;120 g/l (adjusted OR=30.1, p&lt;0.001), despite the use of intra-operative blood salvage. Patients who received allogeneic blood transfusion had a longer hospital stay and greater complication rate. Conclusion Intra-operative blood salvage is not effective in preventing allogeneic blood transfusion in patients with a preoperative haemoglobin level &lt;120 g/l. It should be combined with preoperative optimisation of the haemoglobin level or use of tranexamic acid. </jats:sec

Eigenvalue Dynamics of a Central Wishart Matrix with Application to MIMO Systems

We investigate the dynamic behavior of the stationary random process defined by a central complex Wishart (CW) matrix ${\bf{W}}(t)$ as it varies along a certain dimension $t$. We characterize the second-order joint cdf of the largest eigenvalue, and the second-order joint cdf of the smallest eigenvalue of this matrix. We show that both cdfs can be expressed in exact closed-form in terms of a finite number of well-known special functions in the context of communication theory. As a direct application, we investigate the dynamic behavior of the parallel channels associated with multiple-input multiple-output (MIMO) systems in the presence of Rayleigh fading. Studying the complex random matrix that defines the MIMO channel, we characterize the second-order joint cdf of the signal-to-noise ratio (SNR) for the best and worst channels. We use these results to study the rate of change of MIMO parallel channels, using different performance metrics. For a given value of the MIMO channel correlation coefficient, we observe how the SNR associated with the best parallel channel changes slower than the SNR of the worst channel. This different dynamic behavior is much more appreciable when the number of transmit ($N_T$) and receive ($N_R$) antennas is similar. However, as $N_T$ is increased while keeping $N_R$ fixed, we see how the best and worst channels tend to have a similar rate of change.Comment: 15 pages, 9 figures and 1 table. This work has been accepted for publication at IEEE Trans. Inf. Theory. Copyright (c) 2014 IEEE. Personal use of this material is permitted. However, permission to use this material for any other purposes must be obtained from the IEEE by sending a request to [email protected]

Blood loss in primary total knee arthroplasty-body temperature is not a significant risk factor-a prospective, consecutive, observational cohort study

BACKGROUND: Hypothermia related to anaesthesia and operating theatre environment is associated with increased blood loss in a number of surgical disciplines, including total hip arthroplasty. The influence of patient temperature on blood loss in total knee arthroplasty (TKA) has not been previously studied. METHODS: We recorded patient axillary temperature in the peri-operative period, up to 24 h post-operatively, and analysed the effect on transfusion rate and blood loss from a consecutive cohort of 101 patients undergoing primary TKA. RESULTS: No relationship between peri-operative patient temperature and blood loss was found within the recorded patient temperature range of 34.7–37.8 °C. Multivariable analysis found increasing age, surgical technique, type of anaesthesia and the use of anti-platelet and anticoagulant medications as significant factors affecting blood loss following TKA. CONCLUSION: Patient temperature within a clinically observed range does not have a significant impact on blood loss in primary TKA patients. As long as patient temperature is maintained within a reasonable range during the intra-operative and post-operative periods, strategies other than rigid temperature control above 36.5 °C may be more effective in reducing blood loss following TKA

A MATLAB program for the computation of the confluent hypergeometric function Φ2

We here present a sample MATLAB program for the numerical evaluation of the confluent hypergeometric function Φ2. This program is based on the calculation of the inverse Laplace transform using the algorithm suggested by Simon and Alouini in their reference textbook [1]

Frictions, cracks and micro-resistances: physical activity and sport as strategies to dignify imprisoned women

Discipline and control are key concepts within industrial and capitalist societies. In this context, prisons are a warning tool about the consequences of non-conformity [Foucault, M., 1995. Discipline and Punish: The birth of Prison. NY: Vintage Books]. As a result, punitive power is used as a corrective technique to transform prisoners into docile and useful citizen. However, power in prison is no static and inmates can create various strategies of resistance. The aim of this research is to understand how physical activity and sport are used by incarcerated women to confront social control and negotiate power relations. Underpinned within a critical feminist epistemology, we interviewed 16 women about their prison sports experience. According to the interviewees, physical activity and sport helped them to cope with the sentence while it was a useful tool confronting and negotiating the patriarchal punitive power. The women pointed out that the prison did not fully subdue them. Also, they highlighted their abilities to minimally destabilize the prison order. This enabled them to regain some autonomy and identity, while opposing to the total institution. Engaging in physical practices enabled incarcerated women to create small spaces of freedom and frictions within a limiting a prohibitive prison environmen

Temporal Restriction and Interest for the Elderly on Cultural Participation. The Case of Spanish Performing Arts 2019

This paper discusses the relationship of cultural participation in performing arts with the manifested interest. Using the data set from the Cultural Habits and Practices Survey 2018-2019 a binary probit model has been applied for the analysis. Emphasizing the role of aging in participation, especially for the group of the elderly and very old. The age variable is one of the most difficult variables to apprehend, in which the cohort effects, age itself and period should be considered. This paper is an approach to the study of the aging effect on cultural participation, which would be continued with the analysis of the Surveys in previous years. This work shows that there is no homogeneous behavior between participation and interest within the different performing arts. Presenting some of them differentiating features

A Tractable Line-of-Sight Product Channel Model: Application to Wireless Powered Communications

We here present a general and tractable fading model for line-of-sight (LOS) scenarios, which is based on the product of two independent and non-identically distributed κ- μ shadowed random variables. Simple closed-form expressions for the probability density function and cumulative distribution function are derived, which are as tractable as the corresponding expressions derived from a product of Nakagami-m random variables. This newly proposed model simplifies the challenging characterization of LOS product channels, as well as combinations of LOS channels with non-LOS ones. Results are used to analyze performance measures of interest in the context of wireless powered communications.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Blood Management Strategies in Total Knee Arthroplasty

A perioperative blood management program is one of a number of important elements for successful patient care in total knee arthroplasty (TKA) and surgeons should be proactive in its application. The aims of blood conservation are to reduce the risk of blood transfusion whilst at the same time maximizing hemoglobin (Hb) in the postoperative period, leading to a positive effect on outcome and cost. An individualized strategy based on patient specific risk factors, anticipated blood loss and comorbidities are useful in achieving this aim. Multiple blood conservation strategies are available in the preoperative, intraoperative and postoperative periods and can be employed in various combinations. Recent literature has highlighted the importance of preoperative Hb optimization, minimizing blood loss and evidence-based transfusion guidelines. Given TKA is an elective procedure, a zero allogenic blood transfusion rate should be the aim and an achievable goal