Digital Systolic Blood Pressure Research Articles

Treatment of Dialysis Access-associated Steal Syndrome with the “Revision Using Distal Inflow” Technique

Dialysis access-associated steal syndrome (DASS) is a common, serious complication of antecubital fossa (ACF) arteriovenous fistulas (AVFs). We describe our experience of the "revision using distal inflow" (RUDI) technique for the treatment of DASS and review the literature. Patients underwent fistula ligation at the anastomosis with re-establishment of inflow via the proximal radial or ulnar arteries using a venous interposition graft or venous collateral. A retrospective analysis of outcomes of all patients undergoing this procedure at our center was carried out. Seven patients with autogenous ACF AVFs underwent the RUDI procedure, four under local anesthesia. Interposition vein grafts were used in five patients, and inflow was achieved through the proximal radial artery in four cases. The median post-operative rise in digital systolic blood pressure was 65.5 mmHg. Follow-up at 7-36 months found that three fistulas had failed (one at 8 months, two within days), two patients had died with patent fistulas, one patient was transplanted with a functional AVF, and the remaining patient continues to dialyze through the fistula. No patients developed DASS post-operatively and no further interventions were required to maintain patency. Although RUDI was successful at treating DASS, a high rate of AVF failure was seen. With technical modifications and further experience, RUDI may become a valuable tool in the surgical armamentarium.

Digital thermal hyperaemia impairment does not relate to skin fibrosis or macrovascular disease in systemic sclerosis

Thermal hyperaemia is impaired in patients with systemic sclerosis (SSc). The objective of these studies was to determine whether this was consecutive to skin fibrosis, microangiopathy or macroangiopathy. Using laser Doppler flowmetry, we first compared the thermal hyperaemia on the third left finger pad and on the left forearm in 21 patients with non-diffuse systemic sclerosis (SSc), in comparison with primary Raynaud's phenomenon and healthy volunteers. Second, we tested whether the altered thermal hyperaemia correlated to the digital pressure index at baseline, and following the thermal challenge. In the first study, thermal hyperaemia of the finger pad was impaired in terms of both amplitude and kinetics, but not on the forearm in patients with SSc. In the seven SSc patients without cutaneous fibrosis, the response was similarly altered in terms of amplitude and kinetics. In the second study, we observed a weak correlation between the digital systolic blood pressure index. However, in the 15 SSc patients tested at 44 degrees C, the median digital systolic blood pressure index was 1.04 (0.84-1.24) at baseline vs 1.08 (0.87-1.29) at 44 degrees C (NS), while seven of them had an abnormal response in terms of kinetic. Furthermore, only one patient showed a clear-cut decrease in digital systolic blood pressure at 44 degrees C. In patients with SSc, digital thermal hyperaemia is impaired, but does not relate to the skin fibrosis or to an associated macroangiopathy in most cases. Further studies are required to determine whether its impairment reflects a functional or structural microvascular damage.

Heart rate, arterial stiffness, and wave reflections in paced patients.

Elevated heart rate (HR) and pulse pressure (PP) have a cumulative effect on cardiovascular risk, with the exception of HR >/=100 bpm. How an increase in HR may influence the PP level has never been investigated. In 11 patients with pacemaker monitoring, aortic (pulse-wave analysis) and digital (photoplethysmographic device) blood pressure were measured at 3 different levels of HR, together with determinations of carotid dimensions (echo tracking technique), wave reflections (pulse-wave analysis), and aortic pulse-wave velocity. Increased HR is associated with the following: (1) a significant increase of digital systolic, diastolic, and mean blood pressure; (2) a significant reduction of digital and carotid PP, with a more pronounced reduction of the carotid than of the digital PP, resulting in a significant PP amplification; and (3) a reduction in the time required for the backward pressure wave to return toward the heart, without any change of arterial stiffness. Increased HR significantly enhances PP amplification, leading to an increase of peripheral blood pressure without comparable change in central blood pressure. These results are important to consider for a better understanding of cardiovascular risk and the mechanism of white-coat hypertension.

Invited commentary

The authors assessed the outcome of the Allen’s test compared with the use of the Doppler ultrasound test of the ulnar collateral circulation. They regard the Doppler ultrasound examination of triphasic wave form in the princeps pollicis artery as the “gold standard.” The concerns we have are, firstly, regarding the acceptance of the wave form of the Doppler ultrasound as a gold standard in the assessment of the hand collateral circulation. Baxter and his colleagues [1Baxter BT, Blackburn D, Payne K, Pearce WH, Yao JS. Noninvasive evaluation of the upper extremity. Surg Clin N Am 1990;70:87–97.Google Scholar] state in relation to this test “that the wave form characteristics do not correlate accurately with disease when measured with direct intra-arterial pressure and angiography.”Secondly, the main concern with the Allen’s test is that it may provide a false negative result, thus allowing the surgeon to harvest the artery in a situation where the ulnar collateral circulation is inadequate. The Doppler ultrasound and the digital systolic blood pressure measurements only register the changes occurring immediately following the occlusion of the radial artery and do not provide any information about the subsequent return of the collateral circulation through various compensatory mechanisms. The authors have found that using the Allen’s test with a cut-off point of five seconds results in a false negative rate of 24% (8 of 33). We also found a good correlation between the time of recovery using the Allen’s test compared with the systolic blood pressure in the thumb after occlusion of the radial artery. We concluded that the time of recovery by the Allen’s test of eight seconds achieved the maximum Youden’s index (similar to the ROC curve) and produced a more acceptable false negative rate of 18%.In our unit, 1,500 patients have proceeded to radial artery harvest based on the normal Allen’s test and experienced no complications. Our current recommendation, then, is to perform Doppler ultrasound on all patients who have a positive (abnormal) Allen’s test to prevent those patients, from whom it would be safe to remove the radial artery, being excluded from radial artery harvesting. The authors assessed the outcome of the Allen’s test compared with the use of the Doppler ultrasound test of the ulnar collateral circulation. They regard the Doppler ultrasound examination of triphasic wave form in the princeps pollicis artery as the “gold standard.” The concerns we have are, firstly, regarding the acceptance of the wave form of the Doppler ultrasound as a gold standard in the assessment of the hand collateral circulation. Baxter and his colleagues [1Baxter BT, Blackburn D, Payne K, Pearce WH, Yao JS. Noninvasive evaluation of the upper extremity. Surg Clin N Am 1990;70:87–97.Google Scholar] state in relation to this test “that the wave form characteristics do not correlate accurately with disease when measured with direct intra-arterial pressure and angiography.” Secondly, the main concern with the Allen’s test is that it may provide a false negative result, thus allowing the surgeon to harvest the artery in a situation where the ulnar collateral circulation is inadequate. The Doppler ultrasound and the digital systolic blood pressure measurements only register the changes occurring immediately following the occlusion of the radial artery and do not provide any information about the subsequent return of the collateral circulation through various compensatory mechanisms. The authors have found that using the Allen’s test with a cut-off point of five seconds results in a false negative rate of 24% (8 of 33). We also found a good correlation between the time of recovery using the Allen’s test compared with the systolic blood pressure in the thumb after occlusion of the radial artery. We concluded that the time of recovery by the Allen’s test of eight seconds achieved the maximum Youden’s index (similar to the ROC curve) and produced a more acceptable false negative rate of 18%. In our unit, 1,500 patients have proceeded to radial artery harvest based on the normal Allen’s test and experienced no complications. Our current recommendation, then, is to perform Doppler ultrasound on all patients who have a positive (abnormal) Allen’s test to prevent those patients, from whom it would be safe to remove the radial artery, being excluded from radial artery harvesting.

Chronic critical leg ischaemia must include leg ulcers

In a previous series on conservative treatment in patients with leg ulcers and severe arterial occlusive disease (systolic digital blood pressure (SDBP) < 30 mmHg) a 70% risk of leg amputation and a negligeable potential for ulcerhealing was found. This series assess the efficacy of arterial reconstruction in such patients. Retrospective study of consecutive patients in a department of vascular surgery and of dermatology in cooperation with the wound healing center. Thirty-nine patients with 42 ulcerated legs underwent arterial revascularisation. 88% of the procedures were distal to the inguinal ligament. One patient died postoperatively (3%). Seven (18%) had wound complications, but none had graft infections. After 1 year the cumulative secondary patency was 90%, ulcer healing 70% and the limb salvage 90%. Thus only four legs (10%) had been amputated. Arterial revascularisation for leg ulcers is indicated when conservative treatment fails. Legs with ulceration and SDBP < 30 mmHg should be included in the concept of chronic critical ischaemia.

Correlation of Photoplethysmography, Doppler Velocimetry, Digital Blood Pressure and Skin Temperature in the Hand Under Conditions of Warming

Finger skin temperature (FST) and digital systolic blood pressure (SBP) have long been used as measurements of blood flow in the hand. More recently, attempts have been made to quantify hand blood flow through the use of photoplethysmography (PPG) and Doppler ultrasound (US). Correlation among these measurements has not been documented, either in normals or in persons with pathology. The purpose of this study was to establish the correlations among FST, SBP, PPG, and US under conditions of warming in healthy adults. Ninety-three healthy subjects, 75 females and 18 males aged 18 to 25 years, volunteered to participate in this study of correlation among these variables under resting conditions and various degrees of heat stress. Subjects were systematically divided into a control group that sat quietly, a group that received paraffin dip-and-wrap (av. FST increase of 2.87°F) and a group that received paraffin dip-andreimmerse (av. FST increase of 5.63°F). Measurements were taken on the palmar aspect of the second digit before and after 15 min treatment sessions by a researcher who was blind to the subject's group assignment. Percent change was calculated for each variable under each treatment condition. Correlation analyses revealed no significant correlations among variables in the control group; a weak negative correlation between SBP and FST and a moderate positive correlation between FST and US peak amplitude in the dip-and-wrap group; a strong positive correlation between PPG amplitude and FST and a moderate correlation between PPG amplitude and US peak amplitude in the dip-and-reimmerse group. This leads us to conclude that these variables are not closely related to each other nor do they behave similarly under control conditions. As blood flow is increased by warming, positive correlations among these variables begin to become apparent. The specific measurement of blood flow used should be chosen based on the information required and the conditions under which it will be used.

Effect of temperature on finger artery pressure evaluated by volume clamp technique.

We examined the effect of temperature on digital arterial blood pressure obtained by continuous beat-to-beat non-invasive monitoring with a volume-clamp technique (Finapres). In 10 normal volunteers and 13 patients with symptoms of vasospasm, digital pressure and brachial artery pressure (cuff method) was simultaneously recorded in control conditions at room temperature, during body cooling, finger heating, and truncal heating. In the control condition digital systolic blood pressure was significantly higher (16.1 +/- 14.2 mmHg) than brachial systolic pressure. The augmentation of digital systolic pressure correlated inversely with finger tip temperature. Diastolic and mean arterial pressure did not differ significantly between the two methods. Body cooling augmented the systolic finger-arm gradient while truncal heating and finger heating had the opposite effect. Finger heating reduced systolic augmentation without changing the mean and diastolic blood pressure. Similar changes were also observed in the patients with vasospasm except in one case with a pronounced Raynaud syndrome where digital blood pressure was lower than brachial artery pressure. We conclude that augmentation of finger systolic pressure seems to be dependent on local vasoconstriction of A/V shunts and that finger heating may be a useful procedure to improve the reliability of Finapres readings.

The Allen's test: Analysis of four methods

Forty nonrandomly selected hands were studied with use of four types of Allen's test: (1) the digital systolic blood pressure method, (2) the subjective method, (3) the pulse oximeter method, and (4) the laser Doppler flowmetry method. The digital systolic blood pressure method, regarded as the standard, indicated abnormal pressure in three hands. Laser Doppler flowmetry gave the same results as those obtained by the digital systolic pressure method and, in addition, was easier to perform. Pulse oximetry falsely indicated adequacy of the collateral circulation in two of the three hands with abnormal digital systolic pressure. Eleven hands, including the three with abnormal digital systolic pressure, were abnormal according to the subjective method. The results of the present study indicate the following: (1) the laser Doppler Allen's test is accurate, quick, and easy to perform; (2) the pulse oximeter Allen's test should not be used because of potentially dangerous consequences to the patient in the event of a falsely normal result; and (3) the subjective Allen's test can be used as a quick screening test.

Cardiac baroreflex function during postural change assessed using non-invasive spontaneous sequence analysis in young men

The aim was to assess the value of baroreflex sensitivity estimates calculated from analyses of spontaneous systolic blood pressure and pulse interval sequences derived from continuous non-invasive finger blood pressure recordings during sitting and active standing. Continuous recordings of digital systolic blood pressure and pulse interval were obtained non-invasively using a Finapres FD5 during 5 min trials of sitting and standing. Subjects were healthy males aged 19-28, divided into those with "high" normal (n = 18) and "low" normal (n = 17) blood pressure. Recordings were scanned for spontaneous sequences of three or more cardiac cycles over which systolic blood pressure increased progressively in conjunction with prolonged pulse interval, or decreased while pulse interval became shorter. Regressions between blood pressure and pulse interval (r greater than 0.80) provided estimates of cardiac baroreceptor reflex control. Computations were carried out with concurrent blood pressure and pulse interval measurements, and with a delay or lag of one and two cycles between the two variables. Pulse interval was reduced from an average 870.3 ms sitting to 571.3 ms on standing. Mean baroreflex sensitivity while sitting averaged 17.5 ms.mm Hg-1 at a delay of one cycle, failing to 7.65 ms.mm Hg-1 with standing. The decrease in sensitivity was correlated with the change in pulse interval between trials. The number of sequences was also significantly reduced with standing as opposed to sitting. Three cycle sequences were most frequent, with a lesser number of sequences involving 4, 5, and 6 or more cycles. No significant differences between "high" and "low" normal blood pressure groups were observed. The analysis of spontaneous sequences from non-invasive recordings may provide useful information concerning cardiac baroreflex control in different postural and behavioural states. A lag of one cycle between systolic blood pressure and pulse interval may provide the most representative estimates of baroreflex sensitivity.

Prognostic significance of digital blood pressure in leg ulcer patients.

In a consecutive series of patients with ulceration of the lower leg referred to the dermatological in-patient department during a 9-month period, a systolic digital blood pressure level (SDBP) below 60 mmHg was used to identify patients with complicating arterial occlusive disease (AOD) of the legs. AOD was diagnosed in 25 patients and stasis ulcers from venous disease (SDBP greater than or equal to 60 mmHg) in 38 patients of the same ages. Patients with ulceration from other causes were excluded. After 1 year, 48% of the patients with AOD and 5% of those with stasis ulcers had died. In the AOD group, 11 legs were amputated. Our figures show that the SDBP is valuable in identifying high-risk patients.

The ischaemic leg: a long-term follow-up with special reference to the predictive value of the systolic digital blood pressure. Part II: After arterial reconstruction.

Ninety-five patients with 122 legs with a systolic blood pressure on the big toe below 30 mmHg were the subject of arterial reconstructive surgery. Investigating the limb survival rate we found the systolic blood pressure on the big toe to be the most important predictor, whereas there was found no predictive value of the ankle pressure/index. Preoperative clinical symptoms, which are closely related to the digital blood pressure, were significant predictors of the limb survival rate: the low-pressure limb with no symptoms or intermittent claudication had a significantly higher survival rate than the limb with rest pain and/or gangrene. Following arterial reconstructive surgery the social fate of patients with threatened legs was fairly good as 83% became fully independent.

The ischaemic leg: a long-term follow-up with special reference to the predictive value of the systolic digital blood pressure. Part I: No arterial reconstruction.

The course of 53 patients presenting with 76 legs with ischaemia, defined by blood pressure on the big toe below 30 mmHg, were investigated. The series consists of those patients who after an angiography were considered non-candidates for arterial reconstructive surgery. There were 38 limbs with low pressure and severe ischaemic symptoms, i.e. rest pain and/or gangrene and 38 limbs with low pressures and only intermittent claudication or no leg symptoms at all. There were statistically significant differences in the fate of the limbs in the two groups, the first group suffering a 68 per cent risk of amputations compared to only 16 per cent in the second group. The corresponding risk of death was approximately 60 per cent and 10 per cent. The social fate was poor in the group with rest pain and/or gangrene due to the high number of amputations.

Noninvasive Hemodynamic Assessment of Vasospasm in Patients with Primary Raynaud's Phenomenon

In order to assess vasospastic ischemic disease objectively 41 patients with primary Raynaud's phenomenon and 21 normal volunteers were investigated noninvasively by digital systolic blood pressure and digital skin temperature measurements before and after instant cold provocation. Much care had been taken to be certain that all patients had primary Raynaud's phenomenon. The results of digital pressure measurements appeared to be affected by interindividual variations in systemic systolic blood pressure. By introducing a digit-to-brachial systolic blood pressure index (DBI), such variations could be eliminated. Instant cold provocation did not change DBI significantly. No pressure drop due to a closing phenomenon could be observed. Both digital skin temperature and DBI differed significantly between healthy males and females. In the patient group males and females did not show significant differences. The results in healthy females were hardly different from the results in patients. Healthy males could be well discriminated from patients with both techniques. Sex differentiation appeared to be essential for the objective assessment of primary Raynaud's phenomenon.

Vibration white finger and digital systolic pressure during cooling.

A cold provocation test (measurement of finger systolic pressure during combined body and local finger cooling) was performed on 111 male patients exposed to vibration and with a typical history of cold induced white finger. A new method of calculating the test result is described--namely, digital systolic blood pressure in the cooled test finger as a percentage of the systolic pressure in the arm (DP%). The conventional way of calculating the result, the systolic pressure in the cooled test finger as a percentage of the systolic pressure in the test finger when heated to 30 degrees C, corrected for changes in systemic pressure by the use of a reference finger (FSP%), requires the measurement of the systolic pressure in a reference finger. The two ways of calculating the test results give a similar sensitivity (74% for FSP%, 79% for DP% if all histories are regarded as true) but the new method does not require pressure measurements in a reference finger. This makes the test easier to perform and the result easier to understand.

Digital blood pressure and flow measurements in patients with primary Raynaud's phenomenon.

The value of digital systolic blood pressure (DBP) and flow (DBF) measurements for a quantitative diagnosis of Primary Raynaud's Phenomenon (PRP) was evaluated by comparing the results obtained in 10 patients and 20 normals. Digital skin temperature (DST), DBP and brachial systolic blood pressure (BBP) and DBF were measured at room temperature, at maximal vasodilatation and during cold provocation. At room temperature DST discriminates between normals and patients with an accuracy of 77%. On maximum vasodilatation no significant differences can be found in DBP and DBF between normals and patients. However, DBF was significantly different between male and females both in normals and in patients. During gradual cooling a decrease in DBF (a closing phenomenon) was observed both in normals and patients. In contrast DBP did not show a substantial pressure drop. Calculating digit to brachial systolic pressure indexes (DBI) a slight significant increase can be found during cold provocation both in normals and in patients. Only the DBI of digit IV during cold provocation showed a significant difference between normals and patients which resulted in an accuracy of 83%.

The distal blood pressure predicts healing of amputations on the feet.

The healing of digital and transmetatarsal forefoot amputations was compared with the systolic digital and ankle blood pressure, both measured with a strain-gauge, and with the skin perfusion pressure on the forefoot measured with the isotope washout technique. In 85 out of 134 legs (63 per cent) the amputation healed. The frequency of healing correlated statistically significantly with all three measures of distal blood pressures, the closest correlation being with the systolic digital blood pressure (SDBP). As measured in 110 cases the healing rates were: SDBP less than 20 mm Hg: four out of 23; SDBP 20-29 mm Hg: 13 out of 22; SDBP greater than or equal to 30 mm Hg: 51 out of 65. Ankle pressures and skin perfusion pressures were less useful. Invasive infection was present in 40 out of 102 diabetic legs and, next to ischaemia, was the major determinant of the healing results.

Healing of ulcers on the feet correlated with distal blood pressure measurements in occlusive arterial disease.

The frequency of healing in subchronic ulcers in 66 feet in 62 patients with arterial occlusive disease was correlated with the systolic digital blood pressure (SDBP) and the systolic ankle blood pressure (SABP), both measured with a strain gauge, and with the skin perfusion pressure on the heel (SPPH) as measured with a photocell. Thirty-two patients (35 feet with ulcerations) had diabetes mellitus. The treatment was conservative. In 42 feet the ulcers healed after an average period of 5.8 months; in 24 feet major amputation became necessary after an average of 4.3 months. The frequency of healing correlated significantly with the three distal blood pressure parameters investigated, the closest correlation being with the SDBP measured at the final examination, i.e. just after healing of the ulcer or just before an inevitable major amputation. Of the 22 cases with SDBP below 20 mmHg only two cases (9%) healed. Of the 11 cases with SDBP of 20 to 29 mmHg seven cases (64%) healed and of the 33 cases with SDBP of 30 mmHg or above all cases (100%) healed. There was no significant difference between the 35 diabetic feet and the 31 non-diabetic feet as regards the healing rates, although infection and peripheral neuropathy were frequent in the diabetic group. The data show that the systolic digital blood pressure is a particularly valuable prognostic parameter.

The Measurement of Digital Systolic Blood Pressure by Strain Gauge Technique

The systolic blood pressure on the finger, toe, and ankle has been measured by a strain gauge technique in 10 normal subjects aged 17-31 years and 14 normal subjects aged 43-57 years. The standard deviation in repeated measurements lies between 2 and 6 mm Hg. The finger pressure in the younger group was significantly higher than the corresponding arm pressure (+ 9.3 mm Hg, S.D. 6.8), but equalled this in the older group (- 0.5 mm Hg, S.D. 6.6). In the two groups the ankle pressures were + 19.3 mm Hg (S.D. 7.5) and + 23.6 mm Hg (S.D. 9.5) higher than the systolic arm pressures. The toe pressures were lower than the arm pressures, in the two groups - 4.8 mm Hg (S.D. 6.6) and - 9.8 mm Hg (S.D. 10.7) respectively. The ankle-toe gradient was in the younger group 24.3 mm Hg (S.D. 7.3) and in the older group 33.3 mm Hg (S.D. 12.1). Using mean minus 2.5 X S.D. as the lower limit of normality, arterial stenosis or occlusion in the leg is suggested by ankle pressure below the systolic arm pressure and in the foot by ankle-toe gradient exceeding 43 and 64 mm Hg in the two age groups respectively.