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Continuous ambulatory venous pressure for diagnosis of venous insufficiency
Continuous Ambulatory Venous Pressure for Diagnosis of Venous lnsuff iciency Preliminary Report
Syde A. Taheri, MD, Buffalo, New York David Pendergast, EdD, Buffalo, New York Eliot Lazar, MD, Buffalo, New York Larry H. Pollack, MD, Buffalo, New York Robert M. Shores, AAS, Buffalo, New York Brian McDonald, BA, Buffalo, New York Paul Taheri, BS, Buffalo, New York
It is well known that venous hypertension results in the venous insufficiency syndrome. However, the underlying mechanism of venous insufficiency and its subsequent sequelae has been a subject of little research until recently. In the past, much emphasis was placed on static venous pressure measurements that yielded only single random values which told very little about the dynamics of the venous system. Venous pressure is an accurate determinant of venous disease, but by utilizing continuous venous pressure monitoring, it is possible to correlate pressure changes with clinical symptoms and to detect subclinical venous insufficiency. To the best of our knowledge, the first direct venous pressure measurements were not made until 1925. In this early experiment, using a dorsal vein of the foot, Barber and Shatara [I] recorded resting venous pressures in standing patients. McPheeters et al [2] studied venous pressure measurements in walking patients. Pollack and Wood [3], while using the deep venous systems, showed that alterations in venous pressure occur during postural shifts and exercise. In 1953, Hiijensgard and Stiirup [4] compared the static and dynamic pressures of the superficial and deep veins of the legs. Their results demonstrated close similarities in the two systems, From the Department of Surgery, Millard Fillmore Hospital and Department of Physiology, State University of New York at Buffalo, Buffalo, New York. Requests for reprints should be addressed to Syde A. Taheri. MD, 1275 Delaware Avenue, Buffalo, New York 14209. Presented at tha 13th Annual Meeting of the Society for Clinical Vascular Surgery, Ranch0 Mirage, California, April 10-14. 1985.
Volume 150, August 1985
which led to the conclusion that superficial vein recordings are a valid indicator of venous pressures. Among other experiments, these findings have shown the importance of venous pressure measurement and led to its use as an indicator of venous disease. Material
and Methods
Three groups of subjects were studied. Group I (21 patients, 8 normal control subjects) was tested by the Dynamic Leg Evaluation System@ (DyLES), a portable lightweight monitor. No formal exercise tests were performed in this group. Group II (21 patients, 8 normal control subjects) was measured by a Hewlett Packard monitor (H/P 78905A) and had an initial exercise test. Each person was then monitored for 4 hours but had no follow-up exercise test (Table I). Group III (seven patients, three normal control subjects) was a subgroup of Group II. They had an initial exercise test, 4 hour pressure monitoring, and follow-up exercise testing (Table II). This group was classified by ascending and descending venographic findings, symptoms, and noninvasive studies. The Hewlett Packard monitor was attached by means of a 23 gauge angiographic catheter inserted into a dorsal vein of the foot. The catheter and plastic intravenous connecting tubes were flushed with normal saline solution and 2,000 units of heparin to ensure the system’s patency. The subjects in Groups II and III were then initially tested twice using 10 toe raises as exercise. A heparin lock was inserted and flushed, and the patients rested for 4 hours. In Group I, the DyLES monitor was connected to a pressure amplifier which in turn was linked to a two channel recorder. The first channel is for voice recordings, whereas the second is for pressure readings ranging from
Taheri et al
TABLE I
Venous Pressures in Group II Pallents (values indicated In mm Hg) Patients with VIS (n = 211
Standing Exercise (10 toe raises) Standing/exercise ratio Before test After 4 hr activity Continuous venous pressure rate of increase (/h) Rate of decrease of venous pressure
83 58 1.43 83 a9
during
f f f f f 1.5
2 2 0.12 3 3
Control Subjects (n = 81 63 33 1.91 63 75
f f f f f
3 3 0.15 6 5
TABLE II
Prellminary Findings in Group Ill
Decrease in Venous Pressure During minimal exercise After 4 hours of activity Percent change Obstruction lnsuff iciency VIS = venous insufficiency
Patients With VIS (n = 7)
Control Subjects (n = 3)
2.2 f 0.6 1.9 f 0.7 14 11 16
4.9 f 1.7 3.8 f 1.2 22
.
syndrome.
3 3.6 f 0.3
VIS = venous insufficiency
syndrome.
Figure 2. Continuous venous pressure measurements in standing normal control sub/e& and patients with venous insufficie~y syn&ome. Values are indkakd as fhe mean f the standard error of the mean.
20
Figure 7. Correlationof Dynamic Leg Evaluation System test resuits wifh standard continuous venous pressure ( Pv) measurements.
1 to 100 mg Hg. The DyLES monitor has an 8 hour capability on four 2 hour recording tapes which utilize an audio
encoding system. The DyLES monitor has proved to be hemodynamically safe, simple, and inexpensive [5], and to date, no patients have registered any complaints. We envision the DyLES monitor as a valuable tool in unravelling the pathogenesis of venous insufficiency syndome.
Results
In previous studies, we have shown that data from the DyLES monitor correlated extremely well with standard continuous venous pressure measurements [5] (Figure 1). Because of this, the DyLES monitor readings may be evaluated on a par with venous pressure measurements. Group I, the DyLES group, was observed over a 4 hour period while carrying on normal activity. There was an increase in pressure over this time, with normal patients’ rates increasing 204
3 mm Hg per hour, twice that of the other patients (Figure 2). Initial standing venous pressure readings in Group II were higher in patients with venous insufficiency syndrome than in the control subjects. After a 30 second minimal exercise period, the rate of decrease in venous pressure in patients with venous insufficiency syndrome was 2.5 versus 3.6 or higher in the control subjects, which is a statistically significant difference according to analysis of variance (p <0.05) (Figure 3). A graphic representation shows that venous pressure decreases at a slower rate in patients with venous insufficiency syndrome than in the control subjects (Figure 4). Of the 10 patients in Group III, 3 had normal venous pressures and exercise slopes. Venography correlated well in this group: three control subjects demonstrated normal venographic results, whereas the other seven had
venous insufficiency or obstruction. In addition, exercise tests after 4 hours of normal activity revealed a change in the exercise slope. The results for 0 to 4 hours show a 22 percent decrease in control subjects, and only a 14 percent decrease in patients with venous insufficiency syndrome (Figure 5, Table II). Further subdividing this group by venography into obstructive and insufficiency categories, we found a The American Journal of Surgery
Continuous Ambulatory
Venous Pressure
21 PATIENTS 60
RATE
Of
DECREASE
2 B
2.5
Figure 4. Graphic representation of changes In venous pressures. P 0 = lnltlat reading at rest; PI = pressure after 10 toe raises. The line from To to T, indkates time elapsed, whereas E represents exercise. The equation shows that the s/ape of line E denotes the reiatlve rate of change in venous pressures.
50
d 40 6 NORMALS
RATE DECREASE
30
-
1
I
0
TIME
lsecl
Of 3 6
/
20
Figure 3. Change In venous pressure (Pv) measurements in normal control subjects and in patients with venous insufficfency syndrome during 10 toe raises. Values are indicated at the mean f standard deviation.
Figure 6. Percentage of change in venous pressure stops in normal control subjects and in patients with venous insufficiency syndrome or venous obstruct/on on venograms.
Figure 5. Change In venous pressure ( Pv) slope in normal control subjects and In patients with venous insufficiency syndrome.
16 percent decrease in slope from 0 to 4 hours in the insufficiency group, whereas the obstruction group category had an 11percent change in venous pressure slope (Figure 6).
Comments After exercise, patients with venous insufficiency syndrome had a far higher venous pressure than the control subjects. When the control subjects were compared with the patients with venous insufficiency syndrome, there was a significantly more rapid decrease in the slope of venous pressure during minimal exercise. Similarly, at the end of a 4 hour period, our preliminary data reveal even larger disparity in the Volume 150, August 1995
two slopes. This implies that over an extended period of time, venous pressure continues to be elevated, leading to an increased tissue pressure. It is this increased tissue pressure that we believe is responsible for the clinical symptoms as well as the histopathologic changes seen in venous insufficiency syndrome [6]. The larger disparity in exercise slopes at 4 hours suggests that patients with early venous insufficiency may be asymptomatic at the beginning of the day but may exhibit symptoms after several hours of ambulation. In other words, elevated venous pressure over an extended period of time may result in venous insufficiency syndrome in susceptible patients.
Summary We have found that the venous pressure slope during minimal exercise is a sensitive measurement of venous disease. This parameter differed greatly in 205
Taheri et al
our two study populations. Due to increased venous pressure, venous insufficiency syndrome patients have a greater volume of pooled blood, which results in smaller pressure changes with each muscle contraction. In patients with incompetent valves, blood flows in a retrograde fashion in the vein, which leads to a higher steady state minimal pressure and notably to a decreased venous pressure slope. Venous pressure slope is a particularly sensitive measurement and a good prognosticator of venous insufficiency syndrome before symptoms become disabling to the patient. Our data indicate a strong correlation between venous pressure slope and venographic results. In fact, patients with abnormal venographic results invariably have demonstrated venous pressure slopes in the abnormal range.
206
References 1. Barber RF, Shatara FL. The varicose disease. NY State J Med 1925;31:574. 2. McPheeters’HO, Merkert CE, Lundblad RA. The mechanism of the reverse flow of blood in various veins as proven by blood pressure readings. Surg Gynecol Obstet 1932;55:298. 3. Pollack AA, Wood EH. Venous pressure in the saphenous vein in the ankle in man during exercise and changes in posture. J Appl Physiol 1949;1:849. 4. Mjensgard IC, Stiirup H. Static and dynamic pressures in superficial and deep veins of the lower extremity in man. Acta Physiol Stand 1953;27:49. 5. Taheri SA, Heffner R, Meenaghan MA, et al. Technique and results of venous valve transplantation. In: Bergan JJ, Yao JS, eds. Surgery of the veins. Orlando: Grune 8 Stratton, 1985; 219-31. 6. Taheri SA, Heffner R, Williams J, Lazar L, Elias S. Muscle changes in venous insufficiency. Arch Surg 1984;119: 929-31.
The American Journal of Surgery
Syde A. Taheri, MD, Buffalo, New York David Pendergast, EdD, Buffalo, New York Eliot Lazar, MD, Buffalo, New York Larry H. Pollack, MD, Buffalo, New York Robert M. Shores, AAS, Buffalo, New York Brian McDonald, BA, Buffalo, New York Paul Taheri, BS, Buffalo, New York
It is well known that venous hypertension results in the venous insufficiency syndrome. However, the underlying mechanism of venous insufficiency and its subsequent sequelae has been a subject of little research until recently. In the past, much emphasis was placed on static venous pressure measurements that yielded only single random values which told very little about the dynamics of the venous system. Venous pressure is an accurate determinant of venous disease, but by utilizing continuous venous pressure monitoring, it is possible to correlate pressure changes with clinical symptoms and to detect subclinical venous insufficiency. To the best of our knowledge, the first direct venous pressure measurements were not made until 1925. In this early experiment, using a dorsal vein of the foot, Barber and Shatara [I] recorded resting venous pressures in standing patients. McPheeters et al [2] studied venous pressure measurements in walking patients. Pollack and Wood [3], while using the deep venous systems, showed that alterations in venous pressure occur during postural shifts and exercise. In 1953, Hiijensgard and Stiirup [4] compared the static and dynamic pressures of the superficial and deep veins of the legs. Their results demonstrated close similarities in the two systems, From the Department of Surgery, Millard Fillmore Hospital and Department of Physiology, State University of New York at Buffalo, Buffalo, New York. Requests for reprints should be addressed to Syde A. Taheri. MD, 1275 Delaware Avenue, Buffalo, New York 14209. Presented at tha 13th Annual Meeting of the Society for Clinical Vascular Surgery, Ranch0 Mirage, California, April 10-14. 1985.
Volume 150, August 1985
which led to the conclusion that superficial vein recordings are a valid indicator of venous pressures. Among other experiments, these findings have shown the importance of venous pressure measurement and led to its use as an indicator of venous disease. Material
and Methods
Three groups of subjects were studied. Group I (21 patients, 8 normal control subjects) was tested by the Dynamic Leg Evaluation System@ (DyLES), a portable lightweight monitor. No formal exercise tests were performed in this group. Group II (21 patients, 8 normal control subjects) was measured by a Hewlett Packard monitor (H/P 78905A) and had an initial exercise test. Each person was then monitored for 4 hours but had no follow-up exercise test (Table I). Group III (seven patients, three normal control subjects) was a subgroup of Group II. They had an initial exercise test, 4 hour pressure monitoring, and follow-up exercise testing (Table II). This group was classified by ascending and descending venographic findings, symptoms, and noninvasive studies. The Hewlett Packard monitor was attached by means of a 23 gauge angiographic catheter inserted into a dorsal vein of the foot. The catheter and plastic intravenous connecting tubes were flushed with normal saline solution and 2,000 units of heparin to ensure the system’s patency. The subjects in Groups II and III were then initially tested twice using 10 toe raises as exercise. A heparin lock was inserted and flushed, and the patients rested for 4 hours. In Group I, the DyLES monitor was connected to a pressure amplifier which in turn was linked to a two channel recorder. The first channel is for voice recordings, whereas the second is for pressure readings ranging from
Taheri et al
TABLE I
Venous Pressures in Group II Pallents (values indicated In mm Hg) Patients with VIS (n = 211
Standing Exercise (10 toe raises) Standing/exercise ratio Before test After 4 hr activity Continuous venous pressure rate of increase (/h) Rate of decrease of venous pressure
83 58 1.43 83 a9
during
f f f f f 1.5
2 2 0.12 3 3
Control Subjects (n = 81 63 33 1.91 63 75
f f f f f
3 3 0.15 6 5
TABLE II
Prellminary Findings in Group Ill
Decrease in Venous Pressure During minimal exercise After 4 hours of activity Percent change Obstruction lnsuff iciency VIS = venous insufficiency
Patients With VIS (n = 7)
Control Subjects (n = 3)
2.2 f 0.6 1.9 f 0.7 14 11 16
4.9 f 1.7 3.8 f 1.2 22
.
syndrome.
3 3.6 f 0.3
VIS = venous insufficiency
syndrome.
Figure 2. Continuous venous pressure measurements in standing normal control sub/e& and patients with venous insufficie~y syn&ome. Values are indkakd as fhe mean f the standard error of the mean.
20
Figure 7. Correlationof Dynamic Leg Evaluation System test resuits wifh standard continuous venous pressure ( Pv) measurements.
1 to 100 mg Hg. The DyLES monitor has an 8 hour capability on four 2 hour recording tapes which utilize an audio
encoding system. The DyLES monitor has proved to be hemodynamically safe, simple, and inexpensive [5], and to date, no patients have registered any complaints. We envision the DyLES monitor as a valuable tool in unravelling the pathogenesis of venous insufficiency syndome.
Results
In previous studies, we have shown that data from the DyLES monitor correlated extremely well with standard continuous venous pressure measurements [5] (Figure 1). Because of this, the DyLES monitor readings may be evaluated on a par with venous pressure measurements. Group I, the DyLES group, was observed over a 4 hour period while carrying on normal activity. There was an increase in pressure over this time, with normal patients’ rates increasing 204
3 mm Hg per hour, twice that of the other patients (Figure 2). Initial standing venous pressure readings in Group II were higher in patients with venous insufficiency syndrome than in the control subjects. After a 30 second minimal exercise period, the rate of decrease in venous pressure in patients with venous insufficiency syndrome was 2.5 versus 3.6 or higher in the control subjects, which is a statistically significant difference according to analysis of variance (p <0.05) (Figure 3). A graphic representation shows that venous pressure decreases at a slower rate in patients with venous insufficiency syndrome than in the control subjects (Figure 4). Of the 10 patients in Group III, 3 had normal venous pressures and exercise slopes. Venography correlated well in this group: three control subjects demonstrated normal venographic results, whereas the other seven had
venous insufficiency or obstruction. In addition, exercise tests after 4 hours of normal activity revealed a change in the exercise slope. The results for 0 to 4 hours show a 22 percent decrease in control subjects, and only a 14 percent decrease in patients with venous insufficiency syndrome (Figure 5, Table II). Further subdividing this group by venography into obstructive and insufficiency categories, we found a The American Journal of Surgery
Continuous Ambulatory
Venous Pressure
21 PATIENTS 60
RATE
Of
DECREASE
2 B
2.5
Figure 4. Graphic representation of changes In venous pressures. P 0 = lnltlat reading at rest; PI = pressure after 10 toe raises. The line from To to T, indkates time elapsed, whereas E represents exercise. The equation shows that the s/ape of line E denotes the reiatlve rate of change in venous pressures.
50
d 40 6 NORMALS
RATE DECREASE
30
-
1
I
0
TIME
lsecl
Of 3 6
/
20
Figure 3. Change In venous pressure (Pv) measurements in normal control subjects and in patients with venous insufficfency syndrome during 10 toe raises. Values are indicated at the mean f standard deviation.
Figure 6. Percentage of change in venous pressure stops in normal control subjects and in patients with venous insufficiency syndrome or venous obstruct/on on venograms.
Figure 5. Change In venous pressure ( Pv) slope in normal control subjects and In patients with venous insufficiency syndrome.
16 percent decrease in slope from 0 to 4 hours in the insufficiency group, whereas the obstruction group category had an 11percent change in venous pressure slope (Figure 6).
Comments After exercise, patients with venous insufficiency syndrome had a far higher venous pressure than the control subjects. When the control subjects were compared with the patients with venous insufficiency syndrome, there was a significantly more rapid decrease in the slope of venous pressure during minimal exercise. Similarly, at the end of a 4 hour period, our preliminary data reveal even larger disparity in the Volume 150, August 1995
two slopes. This implies that over an extended period of time, venous pressure continues to be elevated, leading to an increased tissue pressure. It is this increased tissue pressure that we believe is responsible for the clinical symptoms as well as the histopathologic changes seen in venous insufficiency syndrome [6]. The larger disparity in exercise slopes at 4 hours suggests that patients with early venous insufficiency may be asymptomatic at the beginning of the day but may exhibit symptoms after several hours of ambulation. In other words, elevated venous pressure over an extended period of time may result in venous insufficiency syndrome in susceptible patients.
Summary We have found that the venous pressure slope during minimal exercise is a sensitive measurement of venous disease. This parameter differed greatly in 205
Taheri et al
our two study populations. Due to increased venous pressure, venous insufficiency syndrome patients have a greater volume of pooled blood, which results in smaller pressure changes with each muscle contraction. In patients with incompetent valves, blood flows in a retrograde fashion in the vein, which leads to a higher steady state minimal pressure and notably to a decreased venous pressure slope. Venous pressure slope is a particularly sensitive measurement and a good prognosticator of venous insufficiency syndrome before symptoms become disabling to the patient. Our data indicate a strong correlation between venous pressure slope and venographic results. In fact, patients with abnormal venographic results invariably have demonstrated venous pressure slopes in the abnormal range.
206
References 1. Barber RF, Shatara FL. The varicose disease. NY State J Med 1925;31:574. 2. McPheeters’HO, Merkert CE, Lundblad RA. The mechanism of the reverse flow of blood in various veins as proven by blood pressure readings. Surg Gynecol Obstet 1932;55:298. 3. Pollack AA, Wood EH. Venous pressure in the saphenous vein in the ankle in man during exercise and changes in posture. J Appl Physiol 1949;1:849. 4. Mjensgard IC, Stiirup H. Static and dynamic pressures in superficial and deep veins of the lower extremity in man. Acta Physiol Stand 1953;27:49. 5. Taheri SA, Heffner R, Meenaghan MA, et al. Technique and results of venous valve transplantation. In: Bergan JJ, Yao JS, eds. Surgery of the veins. Orlando: Grune 8 Stratton, 1985; 219-31. 6. Taheri SA, Heffner R, Williams J, Lazar L, Elias S. Muscle changes in venous insufficiency. Arch Surg 1984;119: 929-31.
The American Journal of Surgery