Assessing the incremental value of blood oxygen saturation (SpO(2)) in the miniPIERS (Pre-eclampsia Integrated Estimate of RiSk) Risk Prediction Model.

OBJECTIVE: To assess the incremental value of blood oxygen saturation (SpO(2)) as a predictor in the miniPIERS model, a risk prediction model for adverse outcomes among women with a diagnosis of hypertensive disorder of pregnancy (HDP) in low-resourced settings. METHODS: Using data from a prospective cohort including 852 women admitted to hospital for a HDP, the association between SpO(2) and adverse maternal outcome was assessed using logistic regression. The miniPIERS model was recalibrated and extended to include SpO(2). The incremental value of adding SpO(2) to the model was measured using a net reclassification index (NRI), sensitivity, specificity, positive and negative predictive values, and likelihood ratios. RESULTS: SpO(2) of < 93% was associated with a 30-fold increase in risk (95% CI 14 to 68) of adverse maternal outcome compared to women with SpO(2) > 97%. After recalibration and extension, the miniPIERS model including SpO(2) (vs. not including SpO(2)) had improved sensitivity (32.8% vs. 49.6%) at the cost of minimally decreased specificity (91.5% vs. 96.2%) with a NRI of 0.122. CONCLUSION: SpO(2) is a significant independent predictor of risk in women with a HDP. Adding SpO(2) to the miniPIERS model improved the model's ability to correctly identify high-risk patients who would benefit most from interventions.

Objectif : Évaluer la valeur cumulative de la saturation en oxygène (SaO2) à titre de facteur prédictif dans le cadre du modèle miniPIERS, soit un modèle de prévision des risques en ce qui concerne les issues indésirables chez les femmes ayant obtenu un diagnostic de trouble hypertensif de la grossesse (THG) dans des milieux qui ne disposent que de faibles ressources. Méthodes : Grâce à des données issues d'une cohorte prospective ayant porté sur 852 femmes hospitalisées en raison d'un THG, l'association entre la SaO2 et les issues indésirables maternelles a été évaluée au moyen d'une régression logistique. Le modèle miniPIERS a été recalibré et élargi de façon à inclure la SaO2. La valeur cumulative de l'ajout de la SaO2 à ce modèle a été mesurée en ayant recours à l'indice NRI (net reclassification index), à la sensibilité, à la spécificité, aux coefficients de prévision d'un test positif et d'un test négatif et aux rapports de vraisemblance. Résultats : La SaO2 < 93 % a été associée à un risque 30 fois plus élevé (IC à 95 %, 14 - 68) de constater une issue maternelle indésirable, par comparaison avec une SaO2 > 97 %. Après avoir été recalibré et élargi, le modèle miniPIERS comprenant la SaO2 (par comparaison avec le modèle ne comprenant pas la SaO2) présentait une sensibilité améliorée (32,8 % vs 49,6 %); cela a toutefois mené à une baisse minime de la spécificité (91,5 % vs 96,2 %) en présence d'un indice NRI de 0,122. Conclusion : La SaO2 constitue un facteur prédictif indépendant significatif pour ce qui est du risque auquel sont exposées les femmes qui présentent un THG. L'ajout de la SaO2 au modèle miniPIERS a mené à l'amélioration de la capacité de ce dernier à identifier correctement les patientes exposées à des risques élevés qui tireraient le plus avantage de la tenue d'interventions.

The lateral tibial tunnel: does it allow for adequate fixation in ACL surgery?

UNLABELLED: The purpose of this cadaver study about the ACL graft was to compare a "Lateral Tibial Tunnel" (LTT) and a "classic, anteroMedial Tibial Tunnel" (MTT), as to fixation strength and mode of failure. Ten pairs of fresh frozen human proximal tibias were used. In one of both tibias a classic anteromedial tunnel was used, versus a lateral tibial tunnel in the contralateral knee. Autologous doubled semitendinosus and gracilis tendons were fixed in the tunnels. A maximum load to failure test was performed to determine the stiffness and the strength of the graft-tibia complex. CONCLUSION: for none of the measurements was there any significant difference between both tunnels. The tibial fixation strength of a human autologous doubled hamstring graft in ACL surgery is similar, whether a lateral or an anteromedial tibial tunnel is used. This is the first study investigating fixation strength of an ACL graft in a lateral tibial tunnel.

Usability and Feasibility of PIERS on the Move: An mHealth App for Pre-Eclampsia Triage.

BACKGROUND: Pre-eclampsia is one of the leading causes of maternal death and morbidity in low-resource countries due to delays in case identification and a shortage of health workers trained to manage the disorder. Pre-eclampsia Integrated Estimate of RiSk (PIERS) on the Move (PotM) is a low cost, easy-to-use, mobile health (mHealth) platform that has been created to aid health workers in making decisions around the management of hypertensive pregnant women. PotM combines two previously successful innovations into a mHealth app: the miniPIERS risk assessment model and the Phone Oximeter. OBJECTIVE: The aim of this study was to assess the usability of PotM (with mid-level health workers) for iteratively refining the system. METHODS: Development of the PotM user interface involved usability testing with target end-users in South Africa. Users were asked to complete clinical scenario tasks, speaking aloud to give feedback on the interface and then complete a questionnaire. The tool was then evaluated in a pilot clinical evaluation in Tygerberg Hospital, Cape Town. RESULTS: After ethical approval and informed consent, 37 nurses and midwives evaluated the tool. During Study 1, major issues in the functionality of the touch-screen keyboard and date scroll wheels were identified (total errors n=212); during Study 2 major improvements in navigation of the app were suggested (total errors n=144). Overall, users felt the app was usable using the Computer Systems Usability Questionnaire; median (range) values for Study 1 = 2 (1-6) and Study 2 = 1 (1-7). To demonstrate feasibility, PotM was used by one research nurse for the pilot clinical study. In total, more than 500 evaluations were performed on more than 200 patients. The median (interquartile range) time to complete an evaluation was 4 min 55 sec (3 min 25 sec to 6 min 56 sec). CONCLUSIONS: By including target end-users in the design and evaluation of PotM, we have developed an app that can be easily integrated into health care settings in low- and middle-income countries. Usability problems were often related to mobile phone features (eg, scroll wheels, touch screen use). Larger scale evaluation of the clinical impact of this tool is underway.

Development of mHealth applications for pre-eclampsia triage.

The development of mobile applications for the diagnosis and management of pregnant women with pre-eclampsia is described. These applications are designed for use by community-based health care providers (c-HCPs) in health facilities and during home visits to collect symptoms and perform clinical measurements (including pulse oximeter readings). The clinical data collected in women with pre-eclampsia are used as the inputs to a predictive model providing a risk score for the development of adverse outcomes. Based on this risk, the applications provide recommendations on treatment, referral, and reassessment. c-HCPs can access patient records across multiple visits, using multiple devices that are synchronized using a secure Research Electronic Data Capture server. A unique feature of these applications is the ability to measure oxygen saturation with a pulse oximeter connected to a smartphone (Phone Oximeter). The mobile health application development process, including challenges encountered and solutions are described.

The impact of various backboard configurations on compression stiffness in a manikin study of CPR.

When performing cardiopulmonary resuscitation (CPR) it is important that adequate back support is given to the patient in order to allow the medical practitioner to produce an appropriate technique during chest compression (CC). The current study investigates how backboard configuration (i.e., orientation and size) impact compression stiffness during CPR using a torso CPR training manikin. The effect of backboard size on CC performance during CPR was found to be significant with the 94.8% larger backboard producing an increase in compression stiffness of as much as 62.7% relative to the smaller backboard. The impact of backboard orientation was also found to be important with a longitudinal orientation producing an increase in compression stiffness of as much as 60.3% relative to a latitudinal orientation. Backboard configuration should be considered by clinicians when trying to achieve optimal CC performance during CPR in hospital settings.

Towards optimum chest compression performance during constant peak displacement cardiopulmonary resuscitation.

The aim of this study is to determine the conditions necessary to achieve optimum chest compression (CC) performance during constant peak displacement cardiopulmonary resuscitation (CPR). This was accomplished by first performing a sensitivity analysis on a theoretical constant peak displacement CPR CC model to identify the parameters with the highest sensitivity. Next, the most sensitive parameters were then optimized for net sternum-to-spine compression depth, using a two-variable non-linear least squares method. The theoretical CC model was found to be most sensitive to: thoracic stiffness, maximum sternal displacement, CC rate, and back support stiffness. Based on a two-variable, non-linear least squares analysis to optimize the model for the net sternum-to-spine compression depth during constant peak displacement CPR, it was found that the optimum ranges for the CC rate and back support stiffness are between 40-120 cpm and 241.0-1198.5 Ncm⁻¹, respectively. Clinically, this suggests that current ERC guidelines for the CC rate during peak displacement CPR are appropriate; however, practitioners should be aware that the stiffness of the back support surfaces found in many hospitals may be sub-optimal and should consider using a backboard or a concrete floor to enhance CPR effectiveness.

Comparison of experimental chest compression data to a theoretical model for the mechanics of constant peak displacement cardiopulmonary resuscitation.

OBJECTIVES: The objective was to validate an existing theoretical model for the mechanics of constant peak displacement cardiopulmonary resuscitation (CPR) using experimental data taken using various back support surfaces at different chest compression (CC) rates. METHODS: A CPR simulator was used to perform constant peak displacement CC on a weighted full-body CPR training manikin supported on surfaces of varying stiffness at different CC rates. The net sternum-to-spine displacement, combined chest and mattress displacement, and axial reaction force were measured during each test. The experimental results were compared to theoretical predictions from the constant peak displacement CPR model. RESULTS: The theoretical model predictions matched the experimental data to within a mean difference of 11.7% at a CC rate of 42 compressions per minute (cpm), 10.0% at a CC rate of 60 cpm, and 10.1% at a CC rate of 96 cpm, for a target maximum sternal displacement of 5.0 cm. The model predictions also show that when the back support stiffness is less than 250 N/cm, the benefit of using a backboard is greater than for stiffer support surfaces. CONCLUSIONS: Good quantitative agreement between the experimental data and the theoretical model suggests that the constant peak displacement CPR model provides reasonable prediction of CC mechanics during CPR over a wide range of CC rates. Conflicts in the literature are also explained by showing that backboards can significantly enhance CPR CC performance when the back support stiffness is less than 250 N/cm, while for surfaces with higher stiffness, the benefit of using a backboard is reduced.