Day-case diagnostic and interventional peripheral angiography: 10-year experience in a radiology specialist nurse-led unit

We describe a prospective evaluation of the safety of peripheral angiography procedures performed on day-case patients in a dedicated radiological nurse-led and administrated unit. Patients referred for peripheral vascular angiography, over a 10-year period, were pre-assessed by a radiology specialist nurse in a nurse-led clinic. Radiologists performed all procedures, whereas radiology specialist nurses were responsible for patient care before, during and after angiography and during the 24 h follow-up. Procedures were divided into diagnostic or interventional; complications were divided into immediate or delayed (24 h follow-up) either requiring hospital admission (major) or day-case unit management (minor). Patient acceptability was assessed using a standard questionnaire. Cost analysis was also performed. 401 day-case peripheral angiography procedures (144 diagnostic and 257 interventional) were performed in 310 patients. 109/401 (27.2%) procedures were performed on patients with diabetes mellitus. In diagnostic studies, 16/144 (11.1%) immediate and 6/144 (4.2%) delayed complications occurred whereas, in interventional studies, 65/257 (25.3%) immediate and 13/257 (5.1%) delayed complications were noted. A major complication occurred in 17/257 (6.6%) of patients in the interventional group and 3/144 (2.1%) in the diagnostic group. Puncture site haematoma was the most common complication. Nurse-led care was acceptable to the patient, with a high level of patient satisfaction seen. In conclusion, day-case diagnostic and interventional peripheral angiography procedures can be performed safely in a specialist nurse-led and administrated unit, with complication rates being within the accepted guidelines.

The splanchnic circulation and postural hypotension in diabetic autonomic neuropathy

Postural hypotension results from sympathetic failure to cause superior peripheral vasoconstriction. The importance of the splanchnic circulation was studied by measuring mesenteric artery blood flow with duplex Doppler scanning. Nine normal and 9 Type 1 diabetic controls were compared to 8 Type 1 patients with autonomic neuropathy whose pressure fell 40-113 mmHg (range) on tilting. Measurements were made supine and after vertical tilt, fasting without insulin and after a 550 kcal meal. Superior mesenteric artery diameter decreased on tilting in normal controls but not in diabetic control or neuropathy groups (supine vs tilted: controls. 6.3 +/- 0.9 to 5 +/- 0.9 mm, p = 0.004, diabetic controls: 6.0 +/- 0.6 to 6.0 +/- 1.0 mm, and neuropathy group: 6.4 +/- 0.9 to 5.6 +/- 0.9 mm), but proportional blood flow changes were similar in all subjects (controls: 407 +/- 154 to 255 +/- 67 ml min-1 (-31%, p = 0.03), diabetic controls: 379 +/- 140 to 306 +/- 149 ml min-1 (-8%, p = 0.28), neuropathy group: 639 +/- 371 to 435 +/- 142 ml min-1 (-23%, p = 0.10). Postprandially supine superior mesenteric artery flow increased in all subjects but this did not affect the degree of systolic blood pressure drop on tilting (fasting vs postprandial blood flow: controls: 407 +/- 154 to 775 +/- 400 ml min-1 (p = 0.04), diabetic controls: 379 +/- 140 to 691 +/- 262 ml min-1 (p = 0.01), neuropathy group: 639 +/- 371 to 943 +/- 468 ml min-1 (p < 0.06)). The similarity of superior mesenteric artery responses to tilting in the three groups, and the lack of exacerbation of postural hypotension in the presence of postprandial hyperaemia indicates that control of splanchnic blood flow is less important in the aetiology of diabetic autonomic postural hypotension than previously thought.

Lower limb venous pressure in diabetic neuropathy

OBJECTIVE

Distended turgid veins have been noted in the feet of patients with diabetic neuropathy. This study assessed the supine venous pressure and its correlation with diabetic neuropathy and arteriovenous (AV) shunting in the feet of type I and type II diabetic subjects.

RESEARCH DESIGN AND METHODS

Seventeen patients with chronic Charcot joints, 11 patients with a history of neuropathic foot ulceration, 14 diabetic control subjects, and 11 normal control subjects were studied. Neuropathy was assessed by vibration and thermal thresholds and standard cardiovascular autonomic neuropathy tests. Supine venous pressure was measured by insertion of a 21-gauge needle connected to a strain gauge manometer into the veins on the dorsum of the foot. Venous PO2 was used as a measure of AV shunting.

RESULTS

Venous pressure was raised in the group with chronic Charcot joints (18.9 +/- 4.2 mmHg, P < 0.001 vs. the diabetic control group [11.3 +/- 2.6 mmHg]), the normal control group (12.3 +/- 2.3 mmHg, mean +/- SD), and the diabetic group with a history of neuropathic foot ulceration (16.0 +/- 3.7 mmHg, P = 0.008 vs. diabetic control subjects and P = 0.04 vs. normal control subjects), with a maximum of 28 mmHg. Venous pressure was correlated with heart rate variation to deep breathing, r = -0.61 (P = 0.001), vibration threshold, r = 0.56 (P = 0.001), Valsalva ratio, r = -0.64 (P -= 0.001), warm threshold, r = 0.69 (P = 0.001), and venous PO2, r = 0.43 (P = 0.02). There was no correlation with skin temperature, duration of diabetes, age, HbA1c, random blood glucose, ankle/brachial Doppler index, height, or serum creatinine.

CONCLUSIONS

Venous pressure is much higher in the neuropathic diabetic limb and is correlated with the severity of neuropathy and with AV shunting.

Raynaud's phenomenon and cold stress testing: a new approach

There are a number of methods of evaluating digital blood flow in the vascular laboratory but none fulfills the criteria of providing a quick and reproducible diagnostic test for Raynaud's phenomenon. We present our experience with the use of high frequency ultrasound to provide direct real time imaging of the digital arteries. Using this method and a standardised cold challenge test, consisting of exposure of the hand to a temperature of 10 degrees C for 5 minutes, it is possible to distinguish patients with Raynaud's phenomenon from normal controls on the basis of extent of digital artery closure. The mean fall in digital artery diameter on cold challenge, expressed as a percentage of the original diameter, was 92.4% (S.D. = 16.4, S.E.M. = 2.1) in patients with Raynaud's phenomenon as against 8.7% (S.D. = 11.5, S.E.M. = 2.5) in a group of normal volunteers. Using a 45% fall in digital artery diameter as the diagnostic cut-off point, the test has a specificity of 100% and a sensitivity of 96.6% in differentiating patients with Raynaud's phenomenon from controls. It is suggested that the test could be used as objective confirmation of a clinical diagnosis and to assess the efficacy of therapeutic interventions.

Abnormal digital pressure measurements in diabetic neuropathic foot ulceration

The diabetic neuropathic ulcer is typically slow to heal and recurrent. Macrovascular insufficiency is usually excluded as foot pulses are present and ankle:brachial pressure ratios are not decreased. These assessments cannot however exclude more distal vascular disease. Digital pressure measurements enable a reliable assessment of the distal peripheral vascular status to be made. The aim of this study was therefore to use toe pressures to assess the contribution of distal ischaemia in the pathogenesis of the neuropathic ulcer. Sixteen diabetic patients with recurrent neuropathic foot ulceration had their toe pressures compared to 10 neuropathic patients without a history of foot ulceration, 10 diabetic control subjects, and 11 normal subjects. Four non-diabetic patients with neuropathy and foot ulceration were also assessed. All subjects had ankle:brachial pressure indices > or = 1. Toe pressure was assessed using laser Doppler flowmetry to record the return of skin blood flow. The toe:brachial pressure index (TBI) was then calculated. The diabetic patients with a history of recurrent neuropathic ulceration, had the lowest mean TBI, 0.63 +/- 0.14 (SD), compared to the non-ulcerated diabetic neuropathy patients, the diabetic control subjects, and the normal subjects. 0.84 +/- 0.11, 0.82 +/- 0.1, and 0.81 +/- 0.07, p < 0.01, respectively. Three of the four non-diabetic patients with neuropathic foot ulceration also had an abnormally low TBI. Reduced toe pressure measurements are thus found to be associated with neuropathic foot ulceration. The contribution of distal ischaemia in the pathogenesis of the diabetic neuropathic foot ulcer needs to be evaluated.

Falsely raised ankle/brachial pressure index: a method to determine tibial artery compressibility

The ankle/brachial index (abPI) may be falsely raised, notably in diabetes, due to the relative incompressibility of the tibial artery. This paper presents a method of determining tibial artery compressibility by deriving abPIs with the patient supine and with legs raised in increments up to 0.55 m (ankle to heart). The effective negative hydrostatic pressure superimposed on the blood pressure at the ankle was converted to mmHg, normalised with respect to the brachial systolic pressure and then expressed as a hydrostatic pressure index (hPI). abPI was regressed on hPI and the gradient of the regression line calculated. If the arterial wall offers no significant resistance to compression the measured pressure will equal intraluminal pressure. In this case regression of the changing arterial pressure with the applied hydrostatic pressure would be expected to produce a gradient of -1. With resistance to compression the measured pressure is greater than the intraluminal pressure and a steeper gradient would be expected. The method was tested using age and sex matched groups, (A) controls (16 arteries), (B) patients with PVD and no diabetes (17 arteries), and (C) diabetics with PVD (34 arteries). There was no significant difference between the regression line gradients of groups A and B but both differ significantly from group C. The difference between the medians of groups B and C was 0.46, the 95% confidence interval for the difference being 0.66 to 0.02. Twelve of the diabetic arteries had a gradient steeper than -1.8 compared with one from group (B) and none from group (C).(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasound imaging of digital arteries

This study assessed the use of high frequency ultrasound (CUTECH DM70) in the measurement of digital artery diameters. The accuracy of the technique was assessed using a model. Four silicone tubes of different diameters were embedded in opaque agar. Three independent observers measured the diameter of the tubes using the CUTECH DM70 and the measurements obtained were compared with those obtained using a travelling light microscope. The technique was then evaluated on digital arteries. Ten recordings of digital artery diameter were made at a fixed point on the index finger in two subjects at 20 degrees C and at 30 degrees C. There was no statistical difference between the mean diameters obtained by the three observers using the CUTECH DM70 on the model. No statistical difference was noted when the mean diameters measured using the travelling microscope were compared with those obtained by the three observers. The diameter differences between the tubes were all highly significant (P less than 0.001 Mann Witney). The variability in the recordings of digital artery diameter in the two subjects was very low (maximum coefficient of variance less than 4%). A significant difference in the mean measured vessel diameter at the two different temperatures was obtained (P less than 0.001 Mann Witney). We conclude that digital artery diameter can be measured using the CUTECH DM70.

Effects of isosorbide dinitrate on the pattern of arterial blood flow in healthy human subjects

1. Blood velocity measurements have been made in the superficial femoral artery, 10 cm downstream of the common femoral artery bifurcation, in healthy human subjects, using a multi-channel Doppler ultrasound device. 2. In a randomized double-blind protocol, the effects of isosorbide dinitrate were examined during a 2 h period. 3. The changes induced by isosorbide dinitrate include: (i) an increase in the width of the artery and a reduction in brachial arterial blood pressure, implying relaxation of arterial smooth muscle; (ii) an increase in reverse flow and a decrease in time-averaged mean velocity associated with a relatively small decrease of the velocity excursion during the cardiac cycle, implying an increase in flow pulsatility; and (iii) an alteration of the flow pattern both in the core and near the vessel walls.

Raised ankle/brachial pressure index in insulin-treated diabetic patients

The ankle/brachial blood pressure index (A/B PI) is important in the vascular laboratory assessment of peripheral vascular disease. However it is falsely elevated in diabetes, hence underestimating the true severity of disease. We have therefore examined the influence of diabetes on the A/B PI in 2092 patients, 538 with diabetes, all referred for evaluation of peripheral vascular disease. The prevalence of a raised A/B PI (greater than or equal to 1.5) in insulin-treated patients (18.3%) was much higher (p less than 0.001) than that in both non-insulin-treated diabetic patients (4.5%) and patients with no diabetes (2.8%). Insulin-treated patients with a duration of diabetes of greater than 30 years had a higher prevalence of raised A/B PI than those with a duration of less than or equal to 9 years. No significant age effects were seen.

Assessment of regional blood flow and specific microvascular resistance in the foot by means of the transient thermal clearance method

Measurements of skin blood flow have been made in a group of 34 patients presenting with symptoms of peripheral vascular disease. Of the patients, 18 were non-diabetic and the remainder diabetic. Measurements of blood flow were made using the transient thermal clearance method, and of systolic blood pressure in the dorsalis pedis artery using a CW ultrasonic Doppler blood velocimeter and an occluding cuff. There was no difference in pressure index between the two groups. Neither a linear pressure/flow relationship nor the presence of autoregulation was demonstrated. The derivation of specific vascular resistance (SVR) for the two groups shows that in the diabetic it was 7.07 +/- 2.2, while in the non-diabetic it was 11.12 +/- 3.9. The difference is significant (P less than 0.005) and suggests that measurement of SVR may be useful in the differential diagnosis of vascular disease.

Evaluation of a computerised test for the assessment of peripheral vascular disease

This paper reports a study carried out in 200 patients to assess the effectiveness of a clinical vascular laboratory in the routine assessment of peripheral vascular disease (PVD) of the lower limb. Laboratory assessments involved a computer based hierarchical testing system incorporating pedal pressure indices, maximum walking distances and principal component analysis of the common femoral artery blood velocity waveform. The study fell into two parts. In the first, the laboratory assessments of 100 patients referred six years ago were compared retrospectively with their eventual clinical outcome. In this comparison, the laboratory provided a "diagnosis" which was 79% correct. In the second, a double blind prospective study was carried out in 100 patients to compare the vascular laboratory "diagnosis" with the diagnosis and prognosis of a skilled clinician, the outcome being compared one year after the initial assessment. In this study the laboratory proved to be correct in 78% of cases, the clinician in 70%. With a slightly modified computer protocol for the non vascular diagnosis, the computer would have been correct in 85% of cases. This test provides a quantitative and objective assessment of PVD which can assist in the patient's clinical diagnosis and management.

Neoplasia in the rat induced by N-hydroxyphenacetin, a metabolite of phenacetin

N-hydroxyphenacetin, a phenacetin metabolite, was fed to rats as a 0.05-0.5% dietary supplement. After 9 months, tumours of the liver were found in 36 of 64 animals. One animal also developed a renal tumour. No tumours were found in control animals. The findings implicate phenacetin as a carcinogen and suggest that N-hydroxyphenacetin may be the metabolite responsible.