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.

Advancing regulatory science to bring novel medical devices for use in emergency care to market: the role of the Food and Drug Administration.

The Food and Drug Administration (FDA) performs regulatory science to provide science-based medical product regulatory decisions. This article describes the types of scientific research the FDA's Center for Devices and Radiological Health performs and highlights specific projects related to medical devices for emergency medicine. In addition, this article discusses how results from regulatory science are used by the FDA to support the regulatory process as well as how the results are communicated to the public. Regulatory science supports the FDA's mission to assure safe, effective, and high-quality medical products are available to patients.

Accurate STR allele designations at the FGA and vWA loci despite primer site polymorphisms.

Polymerase chain reaction (PCR)-based STR DNA typing systems are used extensively in the field of human identification. Under optimal PCR conditions, the amplicon yield from both alleles of an STR locus is expected to be approximately equivalent. However, it is reasonable to expect that rare genomic sequence polymorphisms will co-localize with well-designed primer sets and induce allele imbalance or "dropouts". Two samples were identified in the course of genotyping thousands of individuals with AmpF/STR Profiler Plus that showed strong disparity in amplitude peak height of heterozygous peaks at the loci vWA and FGA. These samples were reamplified at reduced annealing temperature in an attempt to balance the peak heights. Nucleotide sequencing documented polymorphisms at the PCR primer binding sites of the affected alleles. The results indicate that reducing the annealing temperature to improve primer-binding efficiency at the mismatch and employing an alternative multiplex enhanced the data from both samples. Reducing annealing temperatures could provide a simple general solution to improving data quality for samples where polymorphisms are suspected to cause allele imbalance. Finally, we report on additional polymorphisms surrounding the vWA locus in a genetically diverse population.

Two rare novel polymorphisms in the D8S1179 and D13S317 markers and method to mitigate their impact on human identification.

AIM: Two rare polymorphisms were identified at the primer annealing sites of the short tandem repeat (STR) loci D8S1179 and D13S317 for a commercial multiplex STR system commonly used for human identification. These polymorphisms resulted in weak amplification from the affected alleles. Therefore, alternative polymerase chain reaction (PCR) thermal cycling conditions were developed that promoted more even signal amplitudes from these alleles by employing reduced annealing temperatures. METHODS: Genomic DNA was isolated from bloodstains on FTA paper or cotton cloth. Multiplex genotyping was performed using commercially available reagents. DNA sequences of the affected alleles were determined by using automated instruments. In separate experiments, 96 genetically diverse samples were sequenced to identify polymorphisms surrounding D8S1179 and D13S317. RESULTS: Sequencing the two STR loci, D8S1179 and D13S317, from heterozygous samples that displayed disproportionate signals between alleles revealed a single nucleotide polymorphism (SNP) in each locus that was coincident with the primer annealing sites. Adjusting the primer annealing temperature during the PCR effectively eliminated the amplification bias between alleles due to the mismatched base and improved data quality. No additional polymorphisms were detected at these loci from sequencing 96 genetically diverse samples. CONCLUSION: The technique reported here benefits forensic science practitioners who encounter severe imbalance of heterozygous peaks. This approach is very cost effective, can be used in high-throughput situations, and consumes minimal sample. Finally, understanding polymorphisms at STRs employed for human identification should assist the development of improved reagents to interrogate these loci.