e46 Abstracts / Journal of the American Society of Hypertension 8(4S) (2014) e45–e64

the study further documents that decisions based on ABPM markedly

improve BP control and the corresponding decrease in CVD risk.

Keywords: Ambulatory blood pressure monitoring; Therapeutic decisions;

Blood pressure control; Bedtime treatment

P-48

An adaptive transfer function for deriving the central blood pressure

waveform from a peripheral blood pressure waveform: validation in

patients

Ramakrishna Mukkamala,y,2

Mingwu Gao,2 William Rose,4 Barry Fetics,1

Hao-min Cheng,3 Chen-Huan Chen,3 David Kass.1 1Johns Hopkins

Medical Institution, MD, United States; 2Michigan State University, MI,United States; 3National Yang-ming University, Taiwan; 4University of

Delaware, DE, United States

Central blood pressure (BP) is more important than peripheral BP, but pe-

ripheral BP is easier to measure. While devices are available to derive the

central BP waveform from a peripheral BP waveform, they assume that a

single, universal transfer function exists that can be applied to a peripheral

BP waveform of any subject over any physiologic condition so as to accu-

rately predict the central BP waveform. Hence, this ‘‘generalized transfer

function’’ (GTF) does not adapt to the inter-subject and temporal vari-

ability of the arterial tree and may be prone to excessive error. We previ-

ously proposed a new method to derive the central BP waveform from a

peripheral BP waveform (AJP, 297:H1956-H1963, 2009). The idea is to

adapt the transfer function relating peripheral BP to central BP to the arte-

rial properties of the subject at the time of measurement by using a phys-

ical model and exploiting the fact that ascending aortic blood flow is

negligible during diastole. We also showed proof-of-concept of this ‘‘adap-

tive transfer function’’ (ATF) in laboratory subjects. Our objective here

was to assess the ATF in patients. We studied 49 subjects (75% males

and 24-79 years) undergoing cardiac catheterization. We measured a pe-

ripheral BP waveform via a radial artery tonometer (N ¼ 39) or radial ar-

tery catheter (N ¼ 10) and the reference central BP waveform via a high

fidelity ascending aortic catheter. In some patients (N ¼ 14), we obtained

the waveforms before and after an intervention that perturbed BP (Valsalva

maneuver, abdominal compression, nitroglycerin, or vena cava balloon oc-

clusion). We built a GTF using all of the available central and peripheral

BP waveforms (which represents the best possible, but impractical,

GTF) and another GTF that constitutes a nearly perfect model of the com-

mercial SphygmoCor device (which represents a practical GTF). We

applied the ATF and the GTFs to the peripheral BP waveforms and eval-

uated their predicted central BP against the reference measurements in

terms of systolic BP, pulse pressure, and waveform root-mean-squared-er-

rors (RMSEs). We compared the group average RMSEs of the transfer

functions using paired t-tests (after log transformation of the data). The Ta-

ble shows that the ATF achieved significantly greater accuracy than both

GTFs. The ATF could potentially improve central BP monitoring in clin-

ical practice.

Transfer Function Central Systolic Central Pulse Central BP

BP RMSE

[mmHg]

Pressure RMSE

[mmHg]

Waveform

RMSE [mmHg]

ATF

3.6 � 2.1 3.9 � 2.7 3.2 � 0.8

GTF - Best

possible

4.4 � 2.8 (p < 0.05)

4.8 � 3.6 (p < 0.05) 3.2 � 1.2

GTF - Practical

5.6 � 3.6 (p < 0.001) 7.3 � 4.5 (p < 0.001) 3.7 � 1.5

Keywords: central blood pressure; mathematical model; patient moni-

toring; transfer function

P-49

An online update of knowledge and skills required to get an accurate

blood pressure for public health personnel who measure blood

pressure

Clarence E. Grim,y,3

Namvar Zohoori,1 Carlene M. Grim,4

Linda Faulkner.2 1Arkansas Department of Health, Little Rock, AR, United

States; 2Arkansasa Department of Health, Little Rock, AR, United States;3High Blood Pressure Consulting, Stateline, NV, United States; 4SharedCare Research and Education Consulting, Inc, Stateline, NV, United States

Background: Accurate and reliable blood pressure (BP) measurement is

the key to detection and management. A 2007 Arkansas Cardiovascular

Health Examination Survey (ARCHES) of BP prevalence and control in

Arkansas (AR) revealed one of the highest prevalence rates and among

the lowest control rates in the US. This NHANES-like survey showed

48.3% of Arkansans have high BP and only 39% of those who knew

they had hypertension were controlled.

Method: As part of a statewide BP control program, the AR Dept. of

Health (ADH) implemented a web-based BP measurement quality

improvement program and an interactive DVD version for physicians

and others to assess and update their BP skills (1 hr CME credit). The

BP course began November 1, 2013 and the submitted data include

ADH Local Health Unit (LHU) nurses who took the course in preparation

for a statewide BP survey.

Objectives: At the conclusion of this activity, the participant will be able

to: Identify and discuss the impact of on accuracy of BP readings: two

positioning errors, two observer errors in BPM, the proper way to prepare

client, equipment, and environment according to AHA BP measurement

guidelines.

Results: To date 161 professionals have completed the program (61% were

RNs, 23% LPNs, and 15% public health nurses). The average time spent

on the web-based program was 59 minutes. Pre- post- test criterion based

knowledge scores improved from 55% to 89%. All learning objectives

were met by the program. Feedback on the program by participants

stressed that they would strongly recommend this training to other

colleagues.

Conclusion: This web-based quality improvement program demonstrated

significant improvement in knowledge and performance of BP measure-

ment skills. This should lead to improved BP detection and control in

this important public health problem in Arkansas.

Keywords: public health; BP measurement; quality improvement; online

training

P-50

Asleep, but not clinic or awake blood pressure mean, is an

independent predictor of cardiovascular events: the Hygia Project

Ramon C. Hermida,5 Ana Moya,4 Juan J. Crespo,4 Alfonso Otero,1

Manuel Dominguez-Sardi~na,4 Maria T. Rios,4 Carmen Casti~neira,4

Artemio Mojon,5 Jose R. Fernandez,5 Diana E. Ayala,.5,

Hygia Project Investigators 1Complejo Hospitalario Universitario, Orense,Spain; 2Servicio Galego de Saude, Lugo, Spain; 3Servicio Galego de

Saude, Pontevedra, Spain; 4Servicio Galego de Saude, Vigo, Spain;5University of Vigo, Vigo, Spain

Recent guidelines suggest relying on the awake blood pressure (BP) mean

derived from ambulatory BP monitoring (ABPM) to corroborate the diag-

nosis of hypertension suspected by elevated clinic BP measurement. How-

ever, whether awake BP determines cardiovascular disease risk (CVD)