On the frequency and reproducibility of orthostatic blood pressure changes in healthy community-dwelling elderly during 60-degree head-up tilt

The postural effects of 20 minutes of 60-degree head-up tilt on systolic, diastolic, and mean arterial blood pressures (BPs), heart rate, and rhythm were studied in 70 healthy, community-dwelling volunteer subjects of both sexes, divided into three age groups. Group A consisted of 30 subjects, with a mean age of 76 years (range 65 to 95 years); group B had 19 subjects, with a mean age of 54 years (range 45 to 64 years); and group C had 21 subjects, with a mean age of 33 years (range 24 to 44 years). To qualify, subjects had to have a systolic BP of 150 mm Hg or less and a diastolic BP of < 90 mm Hg, be taking no prescribed medications, have had no previous syncopal episodes, and have absence of any significant medical illness. Nine of 30 (30%) subjects in group A, 1 of 19 (5%) subjects in group B, and 2 of 21 (9.5%) subjects in group C exhibited asymptomatic postural drops in systolic blood pressure > 20 mm Hg (p < 0.05). The mean time for the systolic blood pressure drops in group A was 9.2 minutes. Results were reproducible upon retesting after 1 week. (AM HEART J 1993;126:184-188.)

Archana Patel, MD, Anne Maloney, and Anthony N. Damato, MD Jersey City, N.J.

Orthostatic hypotension is defined as a drop in sys­tolic blood pressure > 20 mm Hg or a drop in dias­tolic blood pressure > 10 mm Hg upon the subject's assuming an upright position.^ The incidence of or­thostatic hypotension in the elderly has been re­ported to vary between 4 % and 33 % .^'^^ Mader,^ in his review of this subject, has enumerated several possible reasons for this variability, which include: types of patients studied (inpatients versus outpa­tients); presence of coexisting diseases; use of medi­cations by study subjects; baseline blood pressure criteria; methods of blood pressure measurements; and differing study protocols. Several investigators have noted a direct correlation between the presence of supine hypertension and the frequency of postural hypotension.^'^' ̂ "̂ *

In an attempt to better define the frequency of or­thostatic hypotension in the older population, Mader et al.^ studied supine to standing blood pressure

From the Division of Cardiology and Geriatric Medicine, Department of Medicine, Jersey City Medical Center; and Seton Hall University School of Graduate Medical Education.

Received for publication Aug. 10, 1992; accepted Jan. 6, 1993.

Reprint requests: Anthony N. Damato, MD, Jersey City Medical Center, Jersey City, NJ 07304.

Copyright ® 1993 by Mosby-Year Book, Inc. 0002-8703/93/$1.00 + .10 4 / 1 / 4 6 2 8 8

changes in 300 community-dwelling elderly individ­uals (mean age 69.3 years) and found the overall in­cidence of postural hypotension to be 10.7%. How­ever, in the group without risk factors, the prevalence was 6.4%, compared with 13.7% in the group with risk factors. Data from this and other reports have suggested that postural hypotension in older subjects is not a normal finding in the absence of identified risk factors and most often is the result of associated diseases or medications.^' '̂ ̂ ^ The present study was undertaken to determine postural changes to a 60-degree head-up tilt in a group of healthy, communi­ty-dwelling elderly persons and to compare these changes with those obtained in a group of young and middle-aged healthy individuals. Additionally, we proposed to test the reproducibility of our findings by restudying any individual with a postural drop of systolic blood pressure > 20 mm Hg after 1 week of the original study.

METHODS

Seventy normal, healthy, community-dwelling volun­teers of both sexes were recruited for this study. There were 28 men and 42 women, whose ages ranged from 24 to 95 years. Subjects were divided into three age groups (see be­low). Patients were screened for the absence of systemic hypertension, other cardiovascular diseases, diabetes, pul­monary and renal diseases, neurologic diseases, lower

184

Volume 126, Number 1

American Heart Journal Patel, Maloney, and Damato 185

a: E E

A

Mean Values Systoiic BP

k T k

Supine 1

1 k

Time (min)

V, k

10 15 20 Supine

• Group A

0 Group B

O Group C

* p < 0.001

Mean Values Diastolic BP

I 40

fo ia JA li, fe fef^ i i

Supine 1 5 10 IS 20 Supine

Time (min)

• Group A O Group B H Group C » p < 0.001

X E E

Mean Values MABP

L u, k ik fa

Supine 1 20 Supine

Time (min)

• Group A Q Groups D Group C * p < 0 05

Mean Values for HR

^M^ '̂

Supme S 10 15 Time (min)

20 Supme

• Group A Q Groups @ Group C • p < 0.05

Fig. 1. A, Mean systolic blood pressure values for the three groups of patients at the seven recording times. (I) denotes standard deviation and (*) denotes statistically significant differences. B, Mean diastolic blood pressure values for the three groups of patients at the seven recording times. (I) denotes standard devia­tion and (*) denotes statistically significant differences. C, Mean values for mean arterial blood pressure in the three groups of patients at the seven recording times. (I) denotes standard deviation. D, Mean heart rate values for the three groups of patients at the seven recording times. (I) denotes standard deviation and (*) denotes statistically significant differences.

extremity varicosities, and electrolyte abnormalities. None had a previous history of syncope. All subjects were in si­nus rhythm. Only one subject in the middle-aged group regularly smoked cigarettes. None were taking any pre­scribed medications. All patients were studied in either the fasting state or in the postabsorptive state. To qualify for the study, subjects had to have a supine systolic blood pressure of 150 mm Hg or less and a diastolic blood pres­sure of less than 90 mm Hg. Systolic and diastolic blood pressures, heart rate, and rhythm were recorded in subjects after 15 minutes of supine rest and at 1, 5, 10, 15, and 20 minutes of 60-degree head-up tilt using a motorized tilt ta­ble with foot board support, and after 10 minutes post tilt with subjects in the supine position. All blood pressure measurements were made from the left arm by a single in­vestigator (A.P) using a standardized arm cuff of a cali­brated mercury sphygmomanometer. The first sound de­tected during deflation of the arm cuff was taken as the systolic blood pressure and the disappearance of the sounds was taken as the diastolic reading. The supine sys­tolic and diastolic blood pressure values immediately before tilt were used as the baseline value and a single blood pressure measurement was taken at the six subsequent

time intervals. Heart rate and rhythm were determined from electrocardiographic recordings made at each stage of the study. Room temperature was maintained at 74° F. Any subject who demonstrated a drop in systolic blood pressure of 20 mm Hg or more during head-up tilt was restudied af­ter 1 week under the same conditions as those of the orig­inal study.

Statistical analysis of the data was performed using the analysis of variance (ANOVA) and unpaired t test where appropriate. The data were also analyzed using age as a continuous variable and by standard regression analysis formulas. Statistical significance was defined as a p value less than 0.05.

RESULTS

Subjects were divided into three age groups. Group A consisted of 30 subjects with a mean age of 76 years (range 65 to 95 years); group B consisted of 19 sub­jects with a mean age of 54 years (range 45 to 64 years); and group C consisted of 21 subjects with a mean age of 33 years (range 24 to 44 years).

Fig. 1, A, B, C, and D depict the mean values for

186 Patel, Maloney, and Damato July 1993

American Heart Journal

Table I. Mean changes during tilt

Group A Group B Group C

Mean systolic BP change (mm Hg)

Mean time for systolic BP change (min)

Mean heart rate change (beats/min)

Mean time for heart rate change (min)

Mean diastolic BP change (mm Hg)

Mean time for diastolic BP change (min)

Mean of mean BP change (min)

Mean time of mean BP change (min)

- 8 (+20 to -30)

8.1 (1 to 20)

+9.6 (+1 to +27)

7.4 (1 to 20)

+2.6 (+14 to -20)

9.4 (1 to 20)

+0.7 (+16 to -22)

10.6 (1 to 20)

-2 .9 (+14 to -22)

7.6 (1 to 20) +10.8

(+30 to -20) 10.4

(1 to 20) +8.8

(+20 to -4 ) 9.2

(1 to 20) +5.0

(+14 t o - 6 ) 9.9

(1 to 20)

- 6 (+10 to -24)

8.4 (1 to 20) +16.1

(+1 to +40) 8.8

(1 to 20) +7.8

(+1 to +20) 8.8

(1 to 20) +5.4

(+16 to - 9 ) 9.0

(1 to 20)

BP, Blood pressure; bracketed values are the ranges.

Table II. Decreases in systolic blood pressure greater than 20 mm Hg

Patient No.

3

15

18

22

23

24

26

27

30

Group A

Maximum decrease

Study 1&2

- 2 4 mm Hg - 2 4 mm Hg - 3 0 mm Hg - 2 0 mm Hg - 3 0 mm Hg - 2 4 mm Hg - 2 0 mm Hg - 3 0 mm Hg - 2 6 mm Hg - 3 4 mm Hg - 2 0 mm Hg - 2 0 mm Hg - 2 6 mm Hg - 2 2 mm Hg - 3 0 mm Hg

-22 mm Hg - 2 0 mm Hg

Time of maximum decrease

20 min 20 min

5 min 6 min

15 min 15 min

1 min 1 min

10 min 10 min

1 min 1 min 5 min 5 min

15 min

15 min 20 min

Patient No.

6

Group B

Maximum decrease

Study 1&2

-22 mm Hg - 2 0 mm Hg

Time of maximum decrease

20 min 20 min

Patient No.

20

21

Group C

Maximum decrease

Study 1&2

- 2 4 mm Hg - 1 6 mm Hg - 2 0 mm Hg -12 mm Hg

Time of maximum decrease

15 min 10 min 20 min 10 min

systolic, diastolic, and mean arterial pressures and heart rate, respectively. For all seven recording times, mean systolic blood pressures for group A were sig­nificantly higher than those for the other two groups (p < 0.001). Only the pre tilt supine mean diastolic blood pressure in group A was significantly higher (p < 0.001). Group A showed statistically significant increases in mean values of mean arterial blood pres­sures for the pre and post tilt supine periods and at the 1-minute tilt stage compared with groups B and

C. Group C had a statistically higher mean heart rate value at the 5-minute tilt period compared with the other two groups.

Table I lists the mean changes and the times of the mean changes in blood pressures and heart rates for the three groups of patients. Although the mean sys­tolic blood pressure changes were not statistically significant between the three groups, a significantly higher percentage of subjects in group A had drops in systolic pressure >20 mm Hg (Table II). The only

Volume 126, Number 1

American Heart Journal Patel, Moloney, and Damato 187

significant changes were in the mean heart rate changes (group C changes were significantly higher [p < 0.02] than group A changes) and the mean dias­tolic blood pressure changes (group A changes were significantly less [p < 0.01] than group B and C changes).

Subjects who exhibited a decrease in systolic blood pressure > 20 mm Hg are listed in Table II. Nine of thirty subjects in group A had a drop in systolic blood pressure > 20 mm Hg. This represented an incidence of 30%, which was significantly higher (p < 0.05) than the 5 % and 9.5 % incidence observed in groups B and C, respectively. The statistical significance of our findings was confirmed when the data were ana­lyzed using age as a continuous variable (p < 0.01). Second-order polynomial regression analysis of our data revealed that systolic blood pressure changes were age-related (F statistic = 0.009, r value = 0.4 [Fig. 2]).

The mean pre tilt resting systolic blood pressure for the nine subjects of group A who exhibited pos­tural hypotension was not significantly different from that of the group as a whole (135 mm Hg vs 132 mm Hg). The mean time for the occurrence of postural hypotension in group A subjects was 9.2 minutes. All 12 subjects exhibiting postural hypoten­sive changes remained asymptomatic. Table II also lists the results of repeat tilt studies performed on eight of nine subjects in group A 1 week after the original studies. All eight subjects exhibited postural hypotension on the second study. All subjects re­mained in sinus rhythm throughout the study and none exhibited ectopic atrial or ventricular activity, atrioventricular, or intraventricular conduction dis­turbances.

DISCUSSION

Using a criterion of a drop in systolic blood pres­sure > 20 mm Hg during a 20-minute head-up tilt protocol, we found a statistically higher incidence of reproducible postural hypotension in our healthy elderly compared with our younger and middle-aged groups. Our results differ from those Mader et al.,* who reported a 6.4% incidence of postural hypoten­sion, as determined during 1 minute of standing in a large group of community-dwelling elderly individu­als with low risk factors for postural hypotension. Also, these investigators did not find a correlation between age and systolic blood pressure change as we did. These differences may in part be explained by differences in the duration of postural stress utilized in the two studies. In this regard, it is interesting to note that four of nine subjects in group A of our study exhibited significant systolic blood pressure changes

40

30

20

y 10-

0. cd o

•5

t 0 w e -10 <u

ra -20 sz O

-30

-40 20 40

1

60 Age

— I — 80 100

Fig. 2. A plot of age versus maximum postural systolic blood pressure changes for all 70 subjects. Second-order polynomial regression analysis reveals postural systolic blood pressure changes related to age (p value = 0.008).

at 5 or less minutes of tilt for an incidence of 13.3% (4 of 30), and that our higher overall incidence (30 %) was the result of five additional subjects who devel­oped postural hypotension in the later stages of the tilt period. This raises the question as to what is the appropriate duration of postural stress in assessing the incidence of postural hypotension in the elderly. A drop in systolic blood pressure > 20 mm Hg occurring during 1 to 3 minutes of standing has be­come the so-called gold standard by which the pres­ence of postural hypotension is judged to be present. Passive head-up tilt > 60 degrees, as used in this study, provides a more controlled and standardized way of extending the duration of postural stress in the elderly. The importance of longer durations of postural stress in the assessment of postural hy­potension in the elderly requires further study.

Our findings also differ from those reported in six studies in which head-up tilt was used to study pos­tural changes in healthy elderly individuals.''"^^ In these studies, tilt angles were between 60 and 70 de­grees and tilt duration varied between 2 and 15 min­utes, with four of the six studies utilizing tilt dura­tions of < 5 minutes. Only the study by Dambrink and Wieling,^^ which used 2 minutes of 70-degree head-up tilt, reported a 13% incidence of postural hypotension in the elderly. However, the allowable entry criteria for a blood pressure in their study was in the hypertensive range (160 to 180/90 mm Hg), which in itself is known to be associated with a higher frequency of postural hypotension.

In considering the importance of the duration of

188 Patel, Maloney, and Damato July 1993

American Heart Journal

Table III. T i l t s tud ies on p a t i e n t s wi th syncope of u n k n o w n origin

Study

Grubb et al.^i

Hackel et a l . "

Kenny et al.^^ Strasberg et al.^^

Abi-Samra et al .^

No. of subjects

25

10

15 40

151

Age mean and range

M 50 ± 16 yr (13-80 yr)

M 71 ± 2 yr (63-80 yr)

M 65 ± 10 yr M 36 ± 19 yr

(10-73 yr) M 5 6 y r

No. of syncopal subjects

6 (24%)

8 (80%)

10 (67%) 15 (37.5%)

63 (42%)

Mean time to syncope (min)

12 ± 4

22*

29 ± 12 42 ± 12

11.7 ± 6.1

M, Mean. •Median value.

postural stress, it is interesting to compare our mean time to postural hypotension (9.2 minutes) with those mean times reported in tilt studies involving patients with syncope of unknown origin in various age groups^^' ̂ "̂̂ * (Table III). In these five studies in­volving a total of 241 patients, in which 60-degree head-up tilt durations of 30 and 60 minutes were uti­lized, the mean time for the development of symp­tomatic hypotension in each study exceeded our mean time for asymptomatic hypotension. There are little to no data available in the literature to which we can compare our data on reproducibility of postural hypotension in healthy elderly subjects during head-up tilt.

We thank Carmen Prado for preparation of the manuscript.

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