Importance of re-calibration time on pulse contour analysis agreement with thermodilution measurements of cardiac output: a retrospective analysis of intensive care unit patients.

We assessed the effect of re-calibration time on cardiac output estimation and trending performance in a retrospective analysis of an intensive care unit patient population using error grid analyses. Paired thermodilution and arterial blood pressure waveform measurements (N = 2141) from 222 patient records were extracted from the Multiparameter Intelligent Monitoring in Intensive Care II database. Pulse contour analysis was performed by implementing a previously reported algorithm at calibration times of 1, 2, 8 and 24 h. Cardiac output estimation agreement was assessed using Bland-Altman and error grid analyses. Trending was assessed by concordance and a 4-Quadrant error grid analysis. Error between pulse contour and thermodilution increased with longer calibration times. Limits of agreement were -1.85 to 1.66 L/min for 1 h maximum calibration time compared to -2.70 to 2.41 L/min for 24 h. Error grid analysis resulted in 74.2 % of points bounded by 20 % error limits of thermodilution measurements for 1 h calibration time compared to 65 % for 24 h. 4-Quadrant error grid analysis showed <75 % of changes in pulse contour estimates to be within ±80 % of the change in the thermodilution measurement at any calibration time. Shorter calibration times improved the agreement of cardiac output pulse contour estimates with thermodilution. Use of minimally invasive pulse contour methods in intensive care monitoring could benefit from prospective studies evaluating calibration protocols. The applied pulse contour analysis method and thermodilution showed poor agreement to monitor changes in cardiac output.

Adaptive Design Practice at the Center for Devices and Radiological Health (CDRH), January 2007 to May 2013.

Adaptive designs have generated great interest in the clinical trial community as a result of their versatility and efficiency. Recently, the Center for Devices and Radiological Health (CDRH) at the US Food and Drug Administration (FDA) surveyed all adaptive design applications submitted between 2007 and May 2013 for regulatory review. In this paper, we discuss the overall results and findings that emerged from an in-depth examination of the submissions. We summarize the current status of adaptive designs used in medical device studies. We also identify some of the lessons learned and common pitfalls that we encountered in our review of the designs.

Evaluation of heart failure biomarker tests: a survey of statistical considerations.

Biomarkers assessing cardiovascular function can encompass a wide range of biochemical or physiological measurements. Medical tests that measure biomarkers are typically evaluated for measurement validation and clinical performance in the context of their intended use. General statistical principles for the evaluation of medical tests are discussed in this paper in the context of heart failure. Statistical aspects of study design and analysis to be considered while assessing the quality of measurements and the clinical performance of tests are highlighted. A discussion of statistical considerations for specific clinical uses is also provided. The remarks in this paper mainly focus on methods and considerations for statistical evaluation of medical tests from the perspective of bias and precision. With such an evaluation of performance, healthcare professionals could have information that leads to a better understanding on the strengths and limitations of tests related to heart failure.

Residual total protein and total organic carbon levels on reprocessed gastrointestinal (GI) biopsy forceps.

Many single-use (disposable) devices are reprocessed between patient uses. In the past, a visual determination was considered the endpoint of "clean" for cleaned reusable devices. In this report, we measured quantitative endpoints by measuring residual total protein and residual total organic carbon before and after cleaning with commercially available cleaners for medical devices on 15 single-use gastrointestinal biopsy forceps inoculated with a three-protein test soil before and after cleaning. Each device was extracted separately and tested using Bradford's reagent for total protein and a direct digestion method for total organic carbon. Data for pre- and post-cleaned devices were generated for all five cleaning cycles. The highest amounts of residual total protein and total organic carbon found on precleaned devices were 61.8 microg/cm(2) and 39.1 microg/cm(2), respectively, on the outer surfaces. The highest amounts of residual total protein and total organic carbon on postcleaned device extracts were 4.0 microg/cm(2) and 2.2 microg/cm(2), respectively, on the outer surfaces. All postcleaned devices were visually clean. Our results provide quantitative total protein and total organic carbon levels for cleaned single-use biopsy forceps.

An empirical comparison of record linkage procedures.

We consider the problem of record linkage in the situation where we have only non-unique identifiers, like names, sex, race etc., as common identifiers in databases to be linked. For such situations much work on probabilistic methods of record linkage can be found in the statistical literature. However, although many groups undoubtedly still use deterministic procedures, not much literature is available on deterministic strategies. Furthermore, there appears to exist almost no documentation on the comparison of results for the two strategies. In this work we compare a stepwise deterministic linkage strategy with a probabilistic strategy, as implemented in AUTOMATCH, for a situation in which the truth is known. The comparison was carried out on a linkage between medical records from the Regional Perinatal Intensive Care Centers database and educational records from the Florida Department of Education. Social security numbers, available in both databases, were used to decide the true status of each record pair after matching. Match rates and error rates for the two strategies are compared and a discussion of their similarities and differences, strengths and weaknesses is presented.