Peripheral BP Research Articles

Comparison of central blood pressure devices on the basis of a modified protocol of the European Society of Hypertension

Central blood pressure (cBP) and pulse pressure amplification (PPA) are receiving renewed interest with the increase in the availability of noninvasive techniques that enable its measurement. However, to date, there is no standardized protocol to validate their accuracy. Although invasive comparison seems intellectually ideal, it will soon raise technical and ethical issues with the growing number of devices to be validated. We proposed a modified ESH-IP2010 protocol for electronic brachial devices to validate noninvasively systolic cBP and pulse pressure amplification, and used it to compare the newly commercialized Centron cBP301 device with radial tonometry SphygmoCor. Radial tonometric SphygmoCor measurements were performed four times alternated with three Centron cBP301 measurements. Each Centron recording was compared with the most favourable SphygmoCor recordings performed immediately before or after and calibrated with Centron peripheral systolic and diastolic blood pressure measurements. Following protocol requirements, 33 individuals (21 men and 12 women) were recruited in the low, medium and high peripheral BP range. Systolic cBP varied from 88 to 188 and the difference between the devices was -0.33±3.28 mmHg (m±SD). It fell within the ESH-IP2010 pass requirements for the number of measurements within 5, 10 and 15 mmHg. The PPA varied from 1.13 to 2.09 and the difference between devices was -0.03±0.11, which showed good agreement for the PPA. The Centron cBP301 device was compared with the similarly calibrated SphygmoCor with a modified ESH-IP2010 protocol. It provided accurate measurements of systolic cBP and PPratio.

Association of Central and Peripheral Blood Pressures With Intermediate Cardiovascular Phenotypes

In conclusion, numerous studies have documented a superior relation of central over brachial BP to intermediate cardiovascular phenotypes or cardiovascular target organ damage. In general, PP has been more strongly related to vascular disease, whereas systolic pressure seems to be a more important determinant of LVH. The similarity of findings in a wide variety of patient-based and population-based studies as well as a broad range of ethnicities supports the robust nature of this phenomenon. Although data regarding the superiority of central over brachial PP with regard to LV diastolic dysfunction are preliminary, the importance of LVH, female sex, and aging as underlying risk factors for HFPEF suggests that more extensive evaluation is likely to reveal a stronger relation of central than peripheral BP with this additional measure of target organ involvement. Finally, limited data suggesting a more important impact of reversing hypertensive cardiovascular hypertrophy by lowering central pressure for a given brachial pressure require confirmation in larger, longitudinal intervention studies.

Vascular and Renal Hemodynamic Changes after Renal Denervation

Renal denervation (RDN) has been shown to be effective in reducing BP in treatment-resistant hypertension. Measurement of the renal and sympathetic activity revealed a decrease in sympathetic drive to the kidney and small resistance vessels after RDN. However, the consequences on renal perfusion and renal vascular resistance (RVR), as well as central hemodynamics, are unknown. Nineteen patients with treatment-resistant hypertension (office BP≥140/90 mmHg, despite at least three antihypertensive drugs [including a diuretic], and diagnosis confirmed by 24-hour ambulatory BP monitoring) underwent RDN between January and October 2011. Renal perfusion and RVR were noninvasively assessed by magnetic resonance imaging with arterial spin labeling, and renal function was assessed by estimating GFR before (day -1), after (day +1), and again after 3 months of RDN. Central hemodynamics was assessed using pulse wave analysis at day -1 and after 6 months of RDN. Peripheral office BP (systolic, 158±26 versus 142±23 mmHg, P=0.002; diastolic, 83±13 versus 76±9 mmHg, P=0.02) and mean systolic 24-hour ambulatory BP (159±17 versus 152±17 mmHg, P=0.02) were significantly reduced 6 months after RDN. Renal perfusion was not statistically different between day -1 and day +1 (256.8 [interquartile range (IQR), 241-278] versus 263.4 [IQR, 252-277] ml/min per 100 g; P=0.17) as well as after 3 months (256.8 [IQR, 241-278] versus 261.2 [IQR, 240-285] ml/min per 100 g; P=0.27) after RDN. RVR dropped (432.1 [IQR, 359-525] versus 390.6 [IQR, 338-461] AU; P=0.02), whereas renal function was not statistically different at any time point. Central systolic BP (145±31 versus 131±28 mmHg; P=0.009), diastolic BP (85±18 versus 80±14 mmHg; P=0.03), and central pulse pressure (61±18 versus 52±18 mmHg; P=0.02) were significantly reduced 6 months after RDN. Central augmentation index (24±8 versus 20±8%; P=0.02) was decreased 6 months after RDN. The data indicate that RDN significantly reduced peripheral and central BP. Despite reduced systemic BP, renal perfusion and function did not change after RDN.

PM.41 Can Pulse Wave Analysis Predict Adverse Obstetric Outcome in Pregnant Women with Chronic Hypertension?

IntroductionComplications of pregnancy including super imposed pre-eclampsia (PE), fetal growth restriction (FGR) and preterm delivery are common in women with chronic hypertension. Outside of pregnancy measurement of arterial stiffness using...

Door to Balloon Times in STEMI Patients: A Five-Year Trend at the Prince Charles Hospital

artery in patients with resistant hypertension. The effect on central BP is less clear. Aim: To compare the effects of RDN on central and peripheral BP. Method: Thirty patients referred to Princess Alexandra Hospital RDN service were screened. Inclusion criteria: (1) peripheral BP >160/90 or (2) 24 ambulatory BP mean >150/90 or (3) home BP diary >150/90 on ≥3 drugs or (4) (i) ≥4 drugs to maintain normotension and (ii) evidence of end organ damage or (5) in the consensus opinion of the RDN Team, unique patient factors are such that the patient could potentially benefit from RDN therapy (e.g. severe intolerance tomultiple medications). Patients were required to undergo a reasonable search for secondary causes and a period of appropriate medical therapy up titration. Central BP was measured non invasively using a SyphgmoCor Device. Results: Thirteen procedures on 12 patients. Eleven males. Mean age 54. Median 6 antihypertensives. Results at six months: peripheral systolic BP reduction from 171± 29mmHg to 160± 31mmHg (mean−11mmHg, 95% CI (−36.4 to 14.4)). Peripheral diastolic BP reduction from 101± 21mmHg to 96± 21mmHg (mean −5mmHg, 95% CI (−27.4 to 17.4)). Central systolic BP reduction from 149± 30mmHg to 143± 36 (mean −6mmHg, 95% CI (−34.3 to 21.8)). Conclusion: In our experience RDN shows a trend to decreasing peripheral brachial BP by a larger amount than central BP. This may have implications for long termmorbidity andmortality benefits. Larger patient numbers will be required to achieve adequate statistical power and the trial is ongoing. http://dx.doi.org/10.1016/j.hlc.2013.05.318

Postchallenge hyperglycemia is closely related with early vascular damage in overweight and obese patients

There is ongoing discussion on how best to screen for diabetes mellitus. Previous studies suggest that an abnormal oral glucose tolerance test (OGTT) is better than fasting glucose levels in predicting cardiovascular mortality, which is largely determined by macrovascular complications in type 2 diabetes. We examined the relationship between screening methods for diabetes and indices of vascular damage in young individuals at high risk of type 2 diabetes. Overweight and obese individuals (n = 76, average age 38 ± 6 years) were screened for diabetes by measuring fasting glucose levels, HbA1c and by performing the OGTT. Indices of early vascular damage, including the central augmentation index (cAIx) and pulse pressure amplification (PPA), were assessed by pulse wave analysis (Sphygmocor). Linear regression analyses were performed to identify independent predictors of vascular damage. Central SBP and DBP (BPs) were best predicted by age and by peripheral BP levels. cAIx was independently predicted by age (r = +0.324, P = 0.008), DBP (r = +0.294, P = 0.011) and 2-h glucose values of the OGTT (r = +0.390, P = 0.001). PPA was independently predicted by age (r = -0.445, P < 0.001) and 2-h glucose value of the OGTT (r = -0.353, P = 0.003). The 2-h value of the OGTT was superior to fasting glucose levels and HbA1c in predicting cAIx and PPA in young individuals at high risk of type 2 diabetes. Cardiovascular mortality is largely determined by macrovascular complications in type 2 diabetes, and these data suggest that diabetes screening by OGTT may help to identify those individuals with the greatest risk of future vascular complications.

DIFFERENTIAL EFFECT OF COCOA DRINKS WITH LOW AND HIGH THEOBROMINE DOSE ON PERIPHERAL AND CENTRAL BLOOD PRESSURE: A DOUBLE BLIND PLACEBO CONTROLLED RANDOMISED CROSS-OVER TRIAL: PP.31.219

Background: Flavonoid containing cocoa products may have a BP lowering effect. It has been suggested that theobromine, due to its vasodilatory properties, could add to this effect. We tested whether flavonoid-rich cocoa drinks low or high in theobromine could lower peripheral and central BP. Methods: In a double-blind placebo-controlled cross-over trial we assigned 42 healthy individuals (32 males, age 62 ± 4.5 yrs) with low CVD risk and office BP of 130-159/85–99 mmHg to a random treatment sequence of acidified-milk drinks containing (1) placebo, (2) cocoa powder with 500 mg flavonoids and low dose (115 mg) theobromine (LDTC) or (3) cocoa powder with 500 mg flavonoids and high dose (1000 mg) theobromine (HDTC). Treatment duration was three weeks with two weeks wash-out. Measurements were done at baseline and after each treatment period. The primary outcome was 24-hour ambulatory BP. Secondary outcome was central BP two hours after consumption of the test product. Outcomes were analysed using linear mixed models with correction for baseline measurements. Results: Treatment with placebo, LDTC and HDTC resulted in a mean 24-hour systolic and diastolic BP (±SE) of 123.9 (1.0)/ 76.4 (0.6), 125.4 (1.0)/ 77.7 (0.6) and 127.2 (1.0)/ 77.8 (0.6) mmHg, respectively (p = 0.02/p = 0.06), while central BP was 128.6 (1.5)/ 82.7 (0.9), 129.5 (1.5)/ 82.8(0.9) and 124.3 (1.5)/ 81.6 (0.9) mmHg (p = 0.001/p = 0.26). Conclusions: Treatment of flavonoid-rich cocoa drinks high in theobromine increased 24-hour ambulatory systolic BP, but lowered central systolic BP compared to placebo. There were no differences in peripheral or central systolic and diastolic BP between the cocoa drink low in theobromine and placebo.

Efficacy of Rg3‐Enriched Korean Red Ginseng (Steamed Panax Ginseng C.A. Meyer) Extract on Arterial Stiffness and Blood Pressure in Healthy Volunteers

ObjectiveTo evaluate the acute effects of 10% Rg3‐enriched Korean Red Ginseng (KRG) on arterial stiffness and peripheral and central systolic (SBP) and diastolic blood pressure (DBP) in healthy adult volunteers.MethodsUsing a double‐blind, randomized, crossover design, 17 individuals (6M:11F; age 25±3; BMI 22±0.8; SBP 111±4, DBP 69±2mmHg) were administered 400mg 10% Rg3‐enriched KRG extract or 400mg corn starch placebo. Aortic augmentation index (AIx) and central BP were measured using applanation tonometry by radial pulse wave analysis and peripheral BP was evaluated oscillometrically. Measurements were taken at baseline and 1,2 and 3hrs post‐treatment.ResultsCompared to placebo, there was a significant reduction in peripheral mean arterial pressure (p=0.046), peripheral DBP (p=0.015), and central SBP (p=0.02) 3hrs post‐treatment. Central DBP and central mean arterial pressure were significantly lower at 1hr (p=0.035, 0.041) and 3hrs (p=0.025, 0.009) post‐treatment. AIx and peripheral SBP also decreased post‐treatment, but this only approached significance (p=0.053).ConclusionsThis study is the first to demonstrate that an Rg3 KRG extract acutely lowers central and peripheral mean arterial pressures in healthy young adults. Further clinical testing is still required as this extract may be more potent in higher‐risk subjects.Sponsor: Heart and Stroke Foundation of Canada

Acute Response of Equicaloric Test Meals Varying in Glycemic Index and Glycemic Load on Postprandial Glycemia, Arterial Stiffness and Blood Pressure in Healthy Adults

ObjectivesThe relative importance of the type of carbohydrate (Glycemic Index, GI) and/or the quantity (Glycemic Load, GL) in the context of a mixed meal on glycemia is still debated; whereas the effects on vascular health are unknown. This study therefore investigated the acute effect all 4 permutations of high and low GI and GL meals on postprandial glycemia and vascular function.MethodsA total of 15 healthy subjects were recruited; preliminary data on the first eight are presented (3M, 5F; age 33 ± 16 y; BMI 21.6 ± 2.7 kg/m2). On 4 separate occasions, subjects received 4 equicaloric meals where the GI and GL levels were manipulated in a block design. Capillary blood samples were collected at fasting and 15, 30, 45, 60, 90, 120, 180 and 240 minutes post‐consumption. Aortic augmentation index (AIx) and central BP were measured hourly using applanation tonometry by radial pulse wave analysis and peripheral BP was evaluated oscillometrically.ResultsThe iAUC blood glucose response after the HiGI‐HiGL and LoGI‐HiGL meals were significantly higher than the LoGI‐LoGL and HiGI‐LoGL meals (p&lt;0.0001), while AIx was significantly reduced at 60min after the HiGI‐LoGL and LowGI‐HiGL meals compared to HiGI‐HiGL (p&lt;0.05).ConclusionsPreliminary data analysis demonstrates that manipulating the GI and GL of a meal result in significantly different blood glucose responses and may acutely modulate vascular function.

Improvement of aortic reflection wave responses 6 months after stopping smoking: a prospective study

Cigarette smoking is one important preventable cause of cardiovascular illness that has been associated with increased stiffness of large arteries and wave reflection, which are independent predictors of cardiovascular disease. We investigated the effect of a 6-month quitting smoking programme on aortic stiffness, central pressure and wave reflections in chronic heavy smokers. Seventy-one (83% normotensives) long-term heavy smokers [>20 cigarettes/day and exhaled carboxy haemoglobin (COHb) (> or =4% and CO ppm > or =21)] completed a 6-month psychological-based stop-smoking program. Patients were divided into two groups. Thirty-one patients aged 45+/-2 years, 71% male, fully quit smoking for 6 months (COHb <2% and CO ppm <10 at 1, 3 and 6 months)--group I, whereas 40 patients aged 45+/-1 years, 73% male, did not change their smoking habits--group II. We measured between baseline and changes after 6 months in aortic stiffness assessed as pulse wave velocity (Complior), central-peripheral pulse pressure (PP) amplification ratio (PPAr), wave reflection (augmentation index corrected for heart rate), augmentation pressure and transit time (Sphygmocor). Ambulatory 24 h blood pressure (ABP) data were obtained at baseline and after 6 months in 36 patients (n = 19) of group I and 17 of group II. In group I, but not in group II, there were significant reductions of peripheral systolic BP (baseline: 131+/-4 to after 6 months: 127+/-4 mmHg, P<0.04) and of systolic BP (baseline: 121+/-4 to after 6 months: 114+/-4 mmHg, P<0.03). In group I from baseline to after 6 months, PPAr increased by 13.1+/-4.1% and transit time (ms) by 8.7+/-2.9%; augmentation index was reduced by 9.2+/-1.6%, augmentation pressure by 5.7+/-1.9 mmHg (all P<0.03 vs. baseline and vs. group II); and pulse wave velocity by 2.3+/-2.8% (P = 0.062). In group I, only daytime ABP was reduced from baseline to after 6 months (129/82+/-2/2 to 123/78+/-2/2 mmHg, P<0.03), whereas no change in 24h-ABP was found in group II. Six months of smoking cessation is associated with clear improvement of reflected waves, central pressure and aortic stiffness, and with a reduction of daytime BP. This may contribute to the improvement of cardiovascular prognosis attributed to smoking cessation.

Effects of Continuous Positive Airway Pressure Treatment and Withdrawal in Patients With Obstructive Sleep Apnea on Arterial Stiffness and Central BP*

Obstructive sleep apnea (OSA) is associated with increased BP and other cardiometabolic risk factors. The aim of the present study was to determine whether arterial stiffness and central BP (two important cardiovascular risk factors) would change, independent of peripheral BP following either the initiation of or withdrawal from nasal continuous positive airway pressure (CPAP) treatment in subjects with OSA. Arterial stiffness and peripheral and central BP were measured at baseline, and then either at 2 months after starting CPAP therapy (intervention group, n=20) or 7 nights after withdrawal from CPAP therapy (withdrawal group, n=20) using pulse wave analysis. In the intervention group, there were reductions in arterial stiffness (ie, the aortic augmentation index fell by 2.5%) and central systolic BP (fell by 4.2 mm Hg) without a concomitant reduction in peripheral BP. The change in arterial stiffness was associated with CPAP compliance (r=-0.47). In contrast, in the withdrawal group there were no overall changes in arterial stiffness or BP. However, there was an early morning increase in diastolic BP and heart rate relative to late evening. These results suggest that clinically important changes in arterial stiffness and central BP may occur following effective CPAP treatment of OSA without parallel changes in peripheral BP.

Arterial stiffness is increased in hypertensive centenarians

Background. The aim of our study was to assess the relationship between blood pressure and arterial stiffness in Polish centenarians. Materials and methods. We examined 59 centenarians with the mean age of 101.3 years. Peripheral blood pressure was estimated upon mean value of three measurements and arterial stiffness by pulse wave analysis (PWA). Pressure waveforms were recorded from the radial artery and the waveform data were then processed by SphygmoCor to produce the estimated aortic pressure waveform. All subjects were divided into the three subgroups: normotensives (<140/90 mmHg), systolic hypertensives (ISH, SBP⩾140 and DBP<90 mmHg) and systolo‐diastolic hypertensives (⩾140/90 or treated). Results. The mean values of peripheral BP for the entire group were: 149.5/76.8 mmHg for SBPP/DBPP and 136.1/77.8 mmHg for central SBPC/DBPC, respectively. The mean value of pulse pressures were: 72.7/58.4 mmHg for peripheral (PPP)/central (PPc). Arterial stiffness indices calculated from PWA were: 96.6%, 33.2% and 32.2% for peripheral (AIxP), central (AIxC) and central normalized for heart rate (AIxC75) augmentation indexes, respectively. The PPc was the lowest in the normotensive group (40.1 mmHg) when compared both with the ISH group (71.1 mmHg) and the systolo‐diastolic group (58.1 mmHg). The lowest arterial stiffness indices (AIxP, AIxC75) calculated from PWA were found in the normotensive group: 85.4% and 28.5%, comparing with 96.1% and 33.7% in the ISH group and 104.8% and 32.9% for the systolo‐diastolic group. Conclusions: In centenarians, similarly to younger subjects, those with hypertension present with arterial stiffness.

Corrigendum

Clinical Physiology and Functional ImagingVolume 25, Issue 5 p. 311-311 Free Access Corrigendum First published: 15 August 2005 https://doi.org/10.1111/j.1475-097X.2005.00627.xAboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat In Sahli et al. (2005), the authors omitted to give a complete description of the methodology for the pole-pox test. The text should have read: Subjects and methods The pole-pox test Because of media sclerosis, patients with diabetes often display a falsely elevated BP when measured at the ankle (Raines et al. 1976). The pole test is a non-invasive method to measure ankle blood pressure (ABP) without interference of media sclerosis, and it has previously been described in detail (Smith et al. 1994). In brief, with the subject lying on the back one leg is elevated until BP at ankle level falls to zero, i.e. disappearance of foot pulses upon Doppler auscultation. At this point, the gravitational pull on the blood column is equal to the systolic BP, and the perpendicular height to which the foot is raised can thus be translated into the systolic arterial BP by using the following formula: peripheral systolic BP (mmHg) = [(Height (cm) − 18)/1·3], 18 being a proxy for the distance between the bed and the patient's heart in cm and 1·3 a coefficient adjusting for the relative density of blood versus mercury. This method can only give peripheral blood pressure readings of approximately <60–65 mmHg, equivalent to a leg elevation of about 100 cm, as a higher elevation of the leg usually is not feasible because of anatomical limitations. In this study, the test was modified, i.e. a so-called ‘pole-pox test’, by monitoring arterial pulses with the pulse oximeter at the great toe instead of Doppler auscultation as described above. Data were obtained in 11 diabetic patients with known LEAD, but because of amputation or technical difficulties, respectively, measurements were unachievable in three legs. In two of the patients measurements were carried out on two separate occasions and both values are used in the analysis. Seven of the 23 measurements were above the detection limit and are not shown (Figure 3). Reference Sahli D, Svensson M, Lidgren J, Öjbrandt K, Eriksson JW. Evaluation of simple non-invasive techniques for assessment of lower extremity arterial disease. Clin Physiol Funct Imaging (2005); 25: 129– 134. Wiley Online LibraryCASPubMedWeb of Science®Google Scholar Volume25, Issue5September 2005Pages 311-311 ReferencesRelatedInformation

Hypertension and Arterial Stiffness After Heart Transplantation

1674 Hypertension is a well recognized complication in heart transplant recipients (HTR) that persists indefinitely following transplantation. Arterial stiffness may play a crucial role in the prevalence (nearly 100%) of post-transplant hypertension. PURPOSE: To noninvasively measure central aortic augmentation index (AIa), an indicator of arterial stiffness, in patients before (PRETX) and after (POSTTX) heart transplantation. METHODS: Prior to and at 2 months after transplantation, a total of 8 HTR (59 yrs of age; n = 7 male; n = 1 female) underwent duplicate measurements of brachial cuff BP by oscillometric sphygmomanometry and radial artery pulse waveform using applanation tonometry. A central aortic BP waveform was synthesized from the measured radial artery pressure waveform using a generalized transfer function and the amplitude and timing of pulse wave reflections were calculated. The same measurements were performed on 8 age- and gender-matched healthy control subjects (CONTR). RESULTS: POSTTX brachial SBP (145 vs 94 mmHg), brachial DBP (90 vs 66 mmHg), and aortic SBP (126 vs 96 mmHg) were significantly greater than PRETX. POSTTX travel time of the aortic reflected pressure wave from the periphery (140 vs 150 msec) was significantly faster. POSTTX travel time of the reflected pressure wave (140 vs 153 msec) was significantly faster and central and peripheral BP and AIa (13 vs 5 %) were significantly greater in HTR compared to healthy CONTR. CONCLUSIONS: Arterial stiffness in patients at 2 months after heart transplantation is greater than in age-matched healthy subjects. Aortic systolic BP augmentation in HTR is due to early return of reflected pressure waves from the lower body and indicates an increase in left ventricular afterload.

Hypertension and Arterial Stiffness After Heart Transplantation

1674 Hypertension is a well recognized complication in heart transplant recipients (HTR) that persists indefinitely following transplantation. Arterial stiffness may play a crucial role in the prevalence (nearly 100%) of post-transplant hypertension. PURPOSE: To noninvasively measure central aortic augmentation index (AIa), an indicator of arterial stiffness, in patients before (PRETX) and after (POSTTX) heart transplantation. METHODS: Prior to and at 2 months after transplantation, a total of 8 HTR (59 yrs of age; n = 7 male; n = 1 female) underwent duplicate measurements of brachial cuff BP by oscillometric sphygmomanometry and radial artery pulse waveform using applanation tonometry. A central aortic BP waveform was synthesized from the measured radial artery pressure waveform using a generalized transfer function and the amplitude and timing of pulse wave reflections were calculated. The same measurements were performed on 8 age- and gender-matched healthy control subjects (CONTR). RESULTS: POSTTX brachial SBP (145 vs 94 mmHg), brachial DBP (90 vs 66 mmHg), and aortic SBP (126 vs 96 mmHg) were significantly greater than PRETX. POSTTX travel time of the aortic reflected pressure wave from the periphery (140 vs 150 msec) was significantly faster. POSTTX travel time of the reflected pressure wave (140 vs 153 msec) was significantly faster and central and peripheral BP and AIa (13 vs 5 %) were significantly greater in HTR compared to healthy CONTR. CONCLUSIONS: Arterial stiffness in patients at 2 months after heart transplantation is greater than in age-matched healthy subjects. Aortic systolic BP augmentation in HTR is due to early return of reflected pressure waves from the lower body and indicates an increase in left ventricular afterload.

Covariation and Temporal Stability of Peripheral and Brachial Blood Pressure Responses to Mental and Static Stress

Abstract Peripheral blood pressure measurement (Finapres technique) is a promising development in activation research. This paper tests and compares the temporal stability and covariation of peripheral and brachial blood pressure responses. Forty healthy subjects were tested four times at intervals of 1 day, 1 week, and 1 month. The tasks employed were two mental tasks (mental arithmetic and a Color Word Test) and a static (fingergrip) task. Recorded physiological parameters were peripheral and brachial systolic (SBP) and diastolic blood pressure (DBP). Mean peripheral SBP was about 20 mmHg higher than brachial SBP, but the difference between the DBP measures was negligible. Correlations between peripheral and corresponding brachial BP resting levels were low, with coefficients below 0.30. The correlations between peripheral and brachial SBP and DBP were higher for reactivity (change) scores (0.46-0.82) than for resting scores. Several types of inter- and intraindividual covariation were calculated to provide a deeper understanding of the relationship between the physiological parameters with respect to their dynamics. Temporal stability of peripheral BP level scores was lower (0.37-0.57) than for brachial BP (0.59-0.77), but the stability of the change scores was similar for both BP techniques. The results show that it is important to distinguish between several aspects of the mutual relationship between peripheral and brachial BP measures. Peripheral BP measurements are not suited to assess the BP level of a subject, but they are very useful to assess cardiovascular reactivity.

1435 COMPARISON OF INTRA-ARTERIAL (IA) AND NON INVASIVE BLOOD PRESSURE (BP) MEASUREMENTS IN SICK NEWBORNS (NB)

Monitoring of BP is necessary for the care of sick NB. A simple, accurate, non invasive method for measuring BP almost continuously would be of great advantage and should reduce the frequency and duration of IA BP monitoring. In 18 critically ill NB, wgt: 840-3460gms.; Gest. Age: 28-42 wks, DX: RDS (13), PFC (2), Asphyxia (2), Sepsis (1),we compared the mean (M), Systolic (S) and Diastolic (D) BP recording from an automatic sphygomomanometer (Dinamap) to the simultaneous IA BP every 4 hours (n=279). Linear regression of peripheral vs. IA mean values (n=18) showed a significant correlation (MBP-r=.96; SBP-r=.96; DBP-r=.98) and slope not significantly different from 1. Average values of the mean differences between peripheral and IA BP were near zero (n=279; MBp=0.5; SBp=0.2; DBp=1.6). Analysis of variance of the individual peripheral - IA differences showed significant variability within and between patients (p<.001). Overall, the within patient variability (±SD) was 12, 16 and 13 torr for MBP, SBP and DBP respectively. Between patient variability was only slightly lower. In conclusion, when a series of measurements are made & averaged, the automatic sphygomomanometer correlates well with IA BP and could be useful for the longitudinal monitoring of sick NB. However, using only a few peripheral determinations could be misleading in estimating the IA BP, due to the large variability.