Abstract Objective To assess the incremental value of blood oxygen saturation (SpO2 ) 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 SpO2 and adverse maternal outcome was assessed using logistic regression. The miniPIERS model was recalibrated and extended to include SpO2 . The incremental value of adding SpO2 to the model was measured using a net reclassification index (NRI), sensitivity, specificity, positive and negative predictive values, and likelihood ratios. Results SpO2 of < 93% was associated with a 30-fold increase in risk (95% CI 14 to 68) of adverse maternal outcome compared to women with SpO2 > 97%. After recalibration and extension, the miniPIERS model including SpO2 (vs. not including SpO2 ) 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 SpO2 is a significant independent predictor of risk in women with a HDP. Adding SpO2 to the miniPIERS model improved the model’s ability to correctly identify high-risk patients who would benefit most from interventions.
Development of mHealth Applications for Pre-Eclampsia Triage Dunsmuir, Dustin T.; Payne, Beth A.; Cloete, Garth ...
IEEE journal of biomedical and health informatics,
2014-Nov., 2014-Nov, 2014-11-00, 20141101, Letnik:
18, Številka:
6
Journal Article
Recenzirano
Odprti dostop
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.
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.
The aim of this study was to assess the usability of PotM (with mid-level health workers) for iteratively refining the system.
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.
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).
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.
Affecting 2–4% of pregnancies, pre-eclampsia is a leading cause of maternal death and morbidity worldwide. Using routinely available data, we aimed to develop and validate a novel machine ...learning-based and clinical setting-responsive time-of-disease model to rule out and rule in adverse maternal outcomes in women presenting with pre-eclampsia.
We used health system, demographic, and clinical data from the day of first assessment with pre-eclampsia to predict a Delphi-derived composite outcome of maternal mortality or severe morbidity within 2 days. Machine learning methods, multiple imputation, and ten-fold cross-validation were used to fit models on a development dataset (75% of combined published data of 8843 patients from 11 low-income, middle-income, and high-income countries). Validation was undertaken on the unseen 25%, and an additional external validation was performed in 2901 inpatient women admitted with pre-eclampsia to two hospitals in south-east England. Predictive risk accuracy was determined by area-under-the-receiver-operator characteristic (AUROC), and risk categories were data-driven and defined by negative (–LR) and positive (+LR) likelihood ratios.
Of 8843 participants, 590 (6·7%) developed the composite adverse maternal outcome within 2 days, 813 (9·2%) within 7 days, and 1083 (12·2%) at any time. An 18-variable random forest-based prediction model, PIERS-ML, was accurate (AUROC 0·80 95% CI 0·76–0·84 vs the currently used logistic regression model, fullPIERS: AUROC 0·68 0·63–0·74) and categorised women into very low risk (–LR <0·1; eight 0·7% of 1103 women), low risk (–LR 0·1 to 0·2; 321 29·1% women), moderate risk (–LR >0·2 and +LR <5·0; 676 61·3% women), high risk (+LR 5·0 to 10·0, 87 7·9% women), and very high risk (+LR >10·0; 11 1·0% women). Adverse maternal event rates were 0% for very low risk, 2% for low risk, 5% for moderate risk, 26% for high risk, and 91% for very high risk within 48 h. The 2901 women in the external validation dataset were accurately classified as being at very low risk (0% with outcomes), low risk (1%), moderate risk (4%), high risk (33%), or very high risk (67%).
The PIERS-ML model improves identification of women with pre-eclampsia who are at lowest and greatest risk of severe adverse maternal outcomes within 2 days of assessment, and can support provision of accurate guidance to women, their families, and their maternity care providers.
University of Strathclyde Diversity in Data Linkage Centre for Doctoral Training, the Fetal Medicine Foundation, The Canadian Institutes of Health Research, and the Bill & Melinda Gates Foundation.
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.
Thesis (MScEng)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The monitoring of patients in healthcare is of prime importance to ensure their;
efficient treatment. The monitoring of blood oxygen ...saturation in tissues;
affected by diseases or conditions that may negatively affect the function is a;
field that has grown in importance in recent times.;
This study involved the development and testing of a highly sensitive noninvasive;
blood oxygen saturation device. The device can be used to continuously;
monitor the condition of tissue affected by diseases which affect the blood flow;
through the tissue, and the oxygen usage in tissue. The device’s system was;
designed to specifically monitor occluded tissue which has low oxygen;
saturations and low perfusion. With the use of the device, it is possible to;
monitor the status of tissue affected by diseases such as meningococcemia and;
diabetes mellitus or conditions such as the recovery after plastic surgery.;
The study delved into all aspects involved in the development of a non-invasive;
artificial pulse oximeter, including but not limited to that of a detailed device;
design, signals analysis, animal in-vivo and laboratory in-vitro system design for;
the calibration of the system as well as human clinical validation and testing;
procedures. All these aspects were compared to determine the relative;
accuracies of the different models.;
Through testing it was shown that it is possible to non-invasively measure the;
mixed oxygen saturation in occluded tissue. However, without accurate;
validation techniques and methods of obtaining both arterial and venous blood;
samples in occluded tissue the system could not be fully validated for;
determining both the arterial and venous oxygen saturations in the human invivo;
study.;
Although the system was unable to accurately measure specifically the venous;
oxygenation it was able to measure the mixed oxygen saturation. With further;
research it would be possible to validate the system for measuring both the;
arterial and venous oxygen saturations.
AFRIKAANSE OPSOMMING: Die monitering van pasiënte in gesondheidsorg is van uiterste belang om;
doeltreffende behandeling te verseker. Die monitering van bloedsuurstofversadiging;
in weefsels wat geaffekteer word deur siektes of toestande wat ’n;
negatiewe impak kan hê op die funksie daarvan is ’n gebied wat aansienlike;
groei getoon het in die onlangse verlede.;
Die studie het die ontwikkeling en toetsing van ’n hoogs sensitiewe nieindringende;
bloedsuurstofversadigingsensor ingesluit. Hierdie sensor kan;
gebruik word om deurentyd die toestand van weefsel te monitor wat;
geaffekteer word deur siektes wat bloedvloei deur weefsel affekteer sowel as;
die suurstofgebruik in die weefsel. Die stelsel is ontwerp om spesifiek die;
ingeslote weefsel wat lae suurstofversadiging en lae perfusie het, te monitor.;
Deur gebruik te maak van die toestel is dit moontlik om die toestand van die;
weefsel wat geaffekteer word deur siektes soos meningococcemia en diabetes;
mellitus of toestande soos die herstel na plastiese sjirurgie te monitor.;
Die studie het gekyk na alle aspekte wat betrokke is in die ontwikkeling van ’n;
nie-indringende kunsmatige pols-oksimeter, insluitend maar nie beperk tot;
gedetailleerde ontwerp nie, sein analise, dier in-vivo en laboratorium in-vitro;
stelselontwerp vir die kalibrasie van die stelsel sowel as menslike kliniese;
bekragtiging en toetsprosedures. Al hierdie aspekte is vergelyk om die relatiewe;
akkuraatheid van die verskillende modelle te bepaal.;
Die toetse het gewys dat dit moontlik is om nie-indringend die gemengde;
suurstofversadiging in weefsel te bepaal. Sonder akkurate bekragtigingstegnieke;
en metodes om beide arteriële en vene bloedmonsters te versamel in ingeslote;
weefsel kan die stesel nie ten volle bekragtig word om beide arteriële- en;
veneversadigings in menslike in-vivo studie te bepaal nie.;
Hoewel die stelsel nie ’n akkurate meting van die aarsuurstof kon kry nie, is daar;
wel ’n akkurate meting geneem van die gemengde suurstofversadiging.;
Toekomstige navorsing kan lei tot die bekragtiging van die stelsel om beide;
arteriële en slagaar suurstofversadigings te meet.
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.
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.
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.
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