1052 Continuous Blood Pressure Monitoring In Sleep

Introduction

Abnormal nocturnal blood pressure(BP) such as non-dipping or nocturnal hypertension(reverse-dipping) represents a potent marker for cardiovascular risks. Standard cuff-based ambulatory nocturnal BP measurement yields limited data points potentially resulting in imprecise results, especially compared to continuously recorded BP. We hypothesized nocturnal BP based on periodic measurement would be different from true average beat-to-beat based BP.

Methods

We prospectively enrolled patients undergoing clinically indicated in-lab polysomnography, both CPAP and non-CPAP studies, for sleep apnea evaluation. Nocturnal BP was continuously monitored beat-to-beat by a noninvasive Caretaker™ device, which uses the Pulse Decomposition Analysis(PDA) algorithm. We compared BP recorded at 30-minute intervals with average BP continuously recorded over 30 minutes, both recorded by Caretaker™. We also looked at the differences between recording spot and continuous BP from an awake or sleeping state and BP variability(SD) based on continuously recorded BP. Using first 30 min as a reference, we determined dipping status (dipping: 10-20% reduction, level: 0-10% reduction, riser: any increase) by the two methods.

Results

A total of 18 patients were recruited(male:11, mean age:52.2). Among a total of 261 periodic BP measurements, 60 (30.0%) were obtained while awake. Mean nocturnal SBP by periodic BP measurement was higher compared with beat-to-beat-derived average BP(135.6mmHg[24.2] vs. 131.5[20.3], p<0.0001). The difference between the two methods remained similar when continuous BP was derived from sleep vs. awake period(4.5mmHg[3.1] vs. 7.7[9.9], p=0.202). BP variability was more pronounced during awake compared with sleep period(6.7mmHg[8.1] versus 3.95[7.5], p=0.047). 8 patients were dippers by spot check measurement, but 11 were dippers by continuous BP.

Conclusion

Standard ambulatory periodic nocturnal BP recording may not yield true sleep BP patterns due to its spot-check nature and lack of sleep-awake information, which leads to inaccurate dipping measurements. Incorporation of beat-to-beat continuous BP measurement can provide more accurate and meaningful nocturnal BP information.

Support

N/A

Effect of Eccentricity of Stiffeners on the General Instability of Stiffened Cylindrical Shells under Hydrostatic Pressure

The general instability of a simply supported cylindrical shell under hydrostatic pressure is analysed by considering the ‘distributed stiffness’ of the frames and stringers separately, taking into account their eccentricity. It is shown that frames on the inside of the shell yield general instability loads about 10–15 per cent greater than frames on the outside of the shell. Stringers are much less effective in stiffening a shell under hydrostatic pressure, and the effect of eccentricity is opposite; outside stringers yield critical loads greater than inside stringers.

Changes in specific markers of haemostasis during reduction mammoplasty

We have investigated the time course of the coagulation and fibrinolytic changes during moderate surgical trauma (elective reduction mammoplasty) in the absence of other confounding factors that could affect haemostasis. Specific markers for coagulation (prothrombin fragment 1.2 (F1.2), thrombin-antithrombin III complex (TAT)) and fibrinolysis (plasmin-antiplasmin complex (PAP) and D-dimer) were examined. Blood samples were obtained in 20 ASA I anaesthetized female patients at T0 (before operation), T75 (during operation) and T150 (before the end of operation). There was a progressive increase in blood loss during operation:mean 110 (SD 80) ml at T75 and 470 (180) ml at T150. This was associated with a significant increase in plasma concentrations of F1.2, PAP and D-dimer at T150 only (P < 0.05 vs T0). We conclude that moderate surgical trauma with blood losses greater than 300 ml can activate thrombin generation and fibrinolysis during operation.

Molecular characterization of an unusual non-Hodgkin's B-lymphoma cell line ("Farage") lacking the ability to produce immunoglobulin polypeptide chains

"Farage" is a cell line derived from a patient who had a diffuse and mixed type malignant lymphoma. In a previous study it was shown that Farage cells expressed B-cell markers, but not membrane IgM. Karyotypic analysis showed that in contrast to most follicular cell lymphomas, Farage did not have the 14;18 chromosomal translocation. In the present work Farage was further characterized by Southern and Northern blot analyses. Two rearranged heavy chain alleles and one rearranged kappa chain gene were detected. The cells expressed both mu and kappa mRNA, even though at a 3-7 fold lower level than that found in the control Daudi and DG-75 Burkitt lymphomas. Farage cells did not express the terminal deoxynucleotydyl transferase gene (TdT), nor the recombination activating genes RAG-1 and RAG-2, known as markers of the pre-B cell stage. These results show that Farage represents a mature B-cell rather than a pre-B cell. Despite the presence of C kappa and C mu RNAs, no Ig polypeptide chains were produced by Farage as judged by immunoblotting and biosynthesis labeling assays. Ig mRNAs were detected on the polysomal fraction, but at a lower level relative to Daudi cells. Our combined results suggest that in Farage cells translation of Ig mRNA is not fully blocked at the stage of translation initiation. Farage cells may express "germline" or mutated variants of Ig mRNAs. The unusual phenotype of Farage may reflect a normal as yet unknown stage of B-cell differentiation, or it may be due to an aberrant expression developed after malignant transformation.