Apparent finger systolic pressures during cooling in patients with Raynaud's syndrome

Raynaud's phenomenon

Raynaud's phenomenon (RP) is a common vasospastic condition which affects ~5% of the general population. The majority of individuals have primary RP; however, Raynaud's can also occur secondary to a broad range of underlying medical conditions and drug therapies. RP is a cardinal feature in patients with systemic sclerosis and is often the earliest symptom of the disease. Unlike primary RP, patients with secondary RP can develop persistent digital ischaemia, including ulcers and gangrene. Patients require a comprehensive clinical assessment and investigation, in particular, the detection of autoantibodies and nailfold capillaroscopic abnormalities. Non-pharmacological management is indicated in all patients. There are a wide range of available drug therapies to treat RP, including when complicated by digital ulceration, and surgical intervention is sometimes required. Future research is needed to understand the complex pathogenesis of RP and to measure the impact and severity of RP to develop optimised approaches to management.

Digital-Artery-Closing Temperatures: An Objective Index of Severity in Raynaud's Phenomenon

Evidence suggests that the color changes of Raynaud's phenomenon (RP) are initiated by spasm of the digital arteries. High-frequency A-mode ultrasound can be used to measure digital artery diameters, and in a group of patients suffering RP, the authors used it to monitor the development of digital artery spasm in fingers that had been progressively cooled. The present study evaluated the reproducibility and value of the temperature at which digital artery spasm occurs (digital-artery-closing temperature) as an objective index of RP severity. Forty-five subjects suffering RP were included (32 suffering primary RP and 13 secondary RP). All were assessed clinically by an independent physician and classified as suffering mild, moderate, or severe RR In 3 of these subjects, digital-artery-closing temperatures were determined on five separate days. The coefficients of variation for digital-artery-closing temperatures recorded in the 3 subjects were low (< 4%), confirming reproducibility. The technique failed in 1 subject suffering severe RP. In the 44 remaining subjects, digital-artery-closing temperatures correlated with clinical assessment. The mean digital-artery-closing temperatures and standard deviations for the three groups were: mild=18.31±1.07°C; moderate=20.83±1.32°C; severe = 25.53±1.38°C. The differences in closing temperatures between the groups were highly significant (P < 0.001, Mann Whitney). The maximum digital artery diameters recorded in the primary RP (including vibration white finger) subjects (Mean±Std Dev=1.21±0.14 mm) were larger than those in the secondary RP subjects (Mean±Std Dev=0.88±0.17 mm). This difference was highly significant (P < 0.001, Mann Whitney).

A vascular mechanistic approach to understanding Raynaud phenomenon

During exposure to cold, our bodies attempt to maintain normal core temperature by restricting heat loss through cutaneous vasoconstriction, and by increasing heat production through shivering and nonshivering thermogenesis. In selected areas of human skin (including on the fingers and toes), the vascular system has specialized structural and functional features that enable it to contribute to thermoregulation. These features include arteriovenous anastomoses, which directly connect the arterial and venous systems and bypass the nutritional capillaries supplying blood to the skin tissue. Of note, Raynaud phenomenon predominantly affects the arterial territories supplying these specialized areas of skin. Indeed, Raynaud phenomenon can be considered a disorder of vascular thermoregulatory control. This Review presents an understanding of Raynaud phenomenon in the context of vascular and thermoregulatory control mechanisms, including the role of unique thermosensitive vascular structural and functional specialization, and describes the potential role of thermogenesis in this disorder. This new approach provides remarkable insight into the disease process and builds a framework to critically appraise the existing knowledge base. This paradigm also explains the deficiencies in some current therapeutic approaches, and highlights new areas of potential relevance to the pathogenesis and treatment of Raynaud phenomenon that should be expanded and explored.

Nonarteriosclerotic vascular disease

Thromboangiitis obliterans, or Buerger disease, is a chronic nonatherosclerotic endarteritis manifesting as inflammation and thrombosis of distal extremity small and medium-sized arteries resulting in relapsing episodes of distal extremity ischemia. Takayasu arteritis is a rare syndrome characterized by inflammation of the aortic arch, pulmonary, coronary, and cerebral vessels, presenting with cerebrovascular symptoms, myocardial ischemia, or upper extremity claudication in young, often female, patients. Kawasaki disease is a small- and medium-vessel acute systemic vasculitis of young children, with morbidity and mortality stemming from coronary artery aneurysms. Microscopic polyangiitis, Churg-Strauss syndrome, and Wegener granulomatosis are systemic small-vessel vasculitides, affecting arterioles, capillary beds and venules, and each presenting with variable effects on the pulmonary, renal and gastrointestinal systems.

Laser Doppler imaging of skin blood flow for assessing peripheral vascular impairment in hand-arm vibration syndrome

The objective of this study was to evaluate the usefulness of laser Doppler imaging (LDPI) of the skin blood flow for assessing peripheral vascular impairment in the hand-arm vibration syndrome (HAVS). The subjects were 46 male patients with HAVS, aged 50 to 69 yr, and 31 healthy male volunteers of similar age as controls. A cold provocation test was carried out by immersing a subject's hand on his more severely affected side into cold water at a temperature of 10 degrees C for 10 min. Repeated image scanning of skin blood flow of the index, middle, and ring fingers was performed every 2 min before, during, and after the cold water immersion using a PMI-II laser Doppler perfusion imager. The mean blood perfusion values in the distal phalanx area of the fingers were calculated on each image. The patients suffering from vibration-induced white finger (VWF, n=20) demonstrated significantly lower skin blood perfusion at each interval of the test as compared with those without VWF (n=26) and the controls (p<0.01, ANOVA). The blood perfusions in the HAVS patients were associated with the severity of the symptoms as classified by the Stockholm Workshop scale for vascular staging. When a subject was considered to be positive if any of the tested fingers showing a decreased blood perfusion and/or a delayed recovery pattern, the sensitivity was 80.0%, and the specificity was 84.6% and 93.5% for patients without VWF and the controls, respectively. These results suggest that the LDPI technique could provide detailed and accurate information that may help detect the existence of impaired vascular regulation to cold exposure in the fingers of workers exposed to hand-transmitted vibration.

Effect of local cold provocation on systolic blood pressure and skin blood flow in the finger

Demonstration of increased vascular cold reactivity in patients with Raynaud's syndrome is difficult. For medico-legal reasons, it is important to get objective measures of vasospasm in these patients. Evaluation of the degree of vasospasm also provides prognostic information which is useful for patient management. In this study, we compare two methods of arterial circulation measurement. The laser Doppler scanning is a new method, which uses the recently developed laser Doppler perfusion imaging (LDPI) instrument. The aim of the present study was to compare the effect on finger skin blood flow measured with LDPI with changes in finger systolic blood pressure during local cold provocation. The effect of such provocation, skin blood flow and systolic blood pressure, were studied in 15 healthy controls. Six patients with known traumatic vasospastic disease (TVD) were also tested with both methods. Finger skin blood flow was measured with LDPI on the distal phalanx of the index finger of the left hand, every minutes during 6 min of local heating at 40 degrees C followed by local cooling for 3 min at 15 degrees C and then for 3 min at 10 degrees C. Finger systolic blood pressure was measured with strain-gauge method before and after local cooling to 10 degrees C with a cuff perfused with water of desired temperature. The test was performed in the same finger within a week of the laser Doppler scanning. Local finger cooling to 15 degrees C and 10 degrees C caused a significant decrease in blood flow, most marked at 10 degrees C. There was, however, no correlation between the decrease in blood flow and blood pressure. In the TVD-patients decreases in skin blood flow were similar compared with the healthy controls. In contrast, the changes in systolic blood pressure, were outside normal range (systolic quotient <0.65) in five of the six patients (83%), and also in 11 of the 15 healthy controls (73%). In conclusion, there is no correlation between the decrease in finger skin blood flow and systolic blood pressure during local cold provocation. For diagnosis of traumatic vasospastic disease (TVD), local cold-induced changes in finger systolic blood pressure seems superior to changes in skin blood flow, but the ideal clinical method for demonstrating increased cold-induced vasospasm is, however, still lacking.

An objective method to estimate the severity of Raynaud phenomenon: digital blood pressure response to cooling

The treatment efficacy of patients with Raynaud phenomenon (RP) is determined from the decrease in severity of this condition, usually based on a decrease in frequency of RP attacks as reported by patients in a diary. Although subjective, this method is still the main endpoint measure in clinical trials. The results of patients' digital blood pressure responses to cooling were compared with the reported RP attack frequency to determine whether the former could be used to estimate the severity of RP. The effect of local finger cooling on the digital systolic blood pressure was tested at 30 degrees C, 20 degrees C, 15 degrees C and 10 degrees C on 136 subjects with RP. The RP attack frequency was dichotomized into daily versus less than daily attacks. The frequency of attacks and the digital systolic pressure (DSP) showed a significant association at all cooling temperatures (those with daily attacks showed lower DSP than those with less frequent attacks). In addition, patients experiencing daily attacks of RP showed a zero reopening pressure at higher local temperatures than those with less frequent RP attacks. These results demonstrate that the response of the digital systolic blood pressure to cooling is closely associated with the RP attack frequency and therefore can be considered as an objective estimate of RP severity. This physiological measurement should be most useful in evaluating the clinical course of RP and the effect of its treatment, provided it is measured under standardized conditions.

The challenge and importance of defining critical limb ischemia

Patients with critical limb ischemia are at risk of limb loss and have very high cardiovascular and total mortality rates, which are greater than can be accounted for by the usual risk factors for atherosclerosis. A definition of critical ischemia is necessary to determine the natural history of the disease and to assess and compare the efficacy of various forms of therapy. The definition needs to be based on hemodynamic criteria because clinical manifestations and outcomes are not reliable. The reasons for the difficulties in arriving at a generally acceptable definition are explored. Building on the previous work of others, modified hemodynamic definitions for critical and subcritical ischemia, which include measurements of pressures and of indices of microcirculation, are proposed.

Pharmacotherapy of Raynaud's phenomenon

Primary Raynaud's phenomenon is common, particularly in younger women, and may be familial. Vasospasm is not confined to the digits and may involve, for example, the tongue and nose, and also visceral organs like the heart, oesophagus or lung and cerebral circulation. Symptoms tend to be milder in primary compared with secondary Raynaud's phenomenon, which is associated with other disorders such as the connective tissue diseases. Indeed, the severity of symptoms often acts as the predictor for the much later onset of the associated systemic disease. Occupational Raynaud's phenomenon is related to the use of vibrating instruments, and a significant proportion of patients may be cured by an early change in job. In those over 60 years of age, Raynaud's phenomenon is commonly a result of atherosclerotic obstructive arterial disease, and screening for and treatment of the risk factors is appropriate. The best-studied mechanisms in Raynaud's phenomenon involve the blood and vascular endothelium. Microcirculatory flow may be impeded by activated platelet clumps, rigid red and white blood cells and damaged endothelium. These platelet clumps, white blood cells and damaged endothelium also release vasoactive/vasoconstrictive compounds which may additionally trigger the clotting cascade and thrombosis. Initial management for mild disease should focus on support and advice regarding avoidance of known precipitating factors, including vasospastic drugs. Cold protection with warming agents, 'Abel' shoes and also electrically heated gloves and socks is effective, but may be too cumbersome and inconvenient for some patients. Simple vasodilators like naftidrofuryl, inositol nicotinate and possibly pentoxifylline (oxpentifylline) are useful in mild disease, with adverse effects like headache and flushing being less problematic. The 'gold standard' of Raynaud's phenomenon treatment is nifedipine, a calcium channel antagonist/blocker. Full dosage, however, can be limited by ankle swelling, headache and flushing, but adverse effects may be reduced by using the 'retard' or long-acting preparations. Adverse effects are also reduced with the newer calcium channel antagonists like diltiazem but at the expense of efficacy. Useful, enhanced benefit is also achieved by combination therapy with vasodilators. Newer treatments include the prostaglandin analogues which are effective but disadvantaged by their parenteral route of administration, and lack of licence in some countries. Oral preparations are, however, being studied and are in the pipeline. Essential fatty acid supplementation is mildly effective, while ketanserin and calcitonin gene-related peptide both look promising. Lumbar sympathectomy retains its important role in the treatment of Raynaud's phenomenon involving the lower limbs. Satisfactory symptomatic relief is now possible for many patients with Raynaud's phenomenon and this should certainly be the aim for all patients seeking medical help.

Cutaneous laser Doppler flowmetry: applications and findings

OBJECTIVE

To examine the historical development, evolution, strengths and weaknesses, and applications (current and future) of laser Doppler flowmetry (LDF).

DESIGN

A review and summary of the literature on the cutaneous uses and successful applications of LDF are presented as well as a brief discussion of the noncutaneous and nonvascular applications.

MATERIAL AND METHODS

LDF measures Doppler-shifted quantities of reflected laser light at a superficial level to determine cutaneous and noncutaneous microcirculatory flux of erythrocytes. LDF is non-invasive and inexpensive.

RESULTS

This relatively recent technologic development has shown considerable potential as a tool for evaluating the cutaneous circulation. Although early studies suggested that LDF had substantial difficulties with sampling, stability, and reproducibility, subsequent refinements in equipment and application have led to technical acceptability.

CONCLUSION

LDF seems to be particularly valuable for assessing the microcirculation and real-time changes in skin blood flow. It has been used successfully in many investigations of the cutaneous and noncutaneous blood flow in patients with fixed or vasospastic vascular disorders, neuropathies, tumors, or ulcers as well as those who have undergone intestinal, orthopedic, or plastic surgical procedures.

Functional study of the dermal microcirculation in systemic sclerosis

To measure the effect of cooling on digital blood pressure we used a strain-gauge and photoplethysmograph, with an automatic cooling device. Eighteen patients were compared with 18 matched controls. Laser-doppler technique was used to measure the perfusion changes after heating a small area of the skin in 5 locations on the body, readings were given in perfusion units. Eighteen patients with systemic sclerosis were compared with 25 individuals with primary Raynaud's phenomenon and 30 healthy controls. Cooling to 10 degrees C caused a significant digital blood pressure drop of 58 mmHg in patients with systemic sclerosis and 61 mmHg in Raynaud's phenomenon, as compared with controls. The microcirculation in patients with systemic sclerosis responded in the same way to local heating as in the normal population, increasing the perfusion to the same extent. In conclusion, an unselected group of patients with systemic sclerosis have normal dermal microcirculatory response to heating in spite of severe cold intolerance.

The effect of cooling on toe systolic pressures in subjects with and without Raynaud's syndrome in the lower extremities

The effect of changes in local and body temperature on the toe systolic pressures was studied in 20 subjects with and 30 without Raynaud's syndrome in the toes. The pressures were significantly lower in the group with Raynaud's syndrome under all experimental conditions (P less than 0.01). The pressures were significantly lower during body cooling than during body warming in both groups (P less than 0.01). The mean decrease with body cooling was 58 mmHg in the group with Raynaud's syndrome and 24 mmHg in the control subjects (P less than 0.01). During body cooling pressures fell to less than 30 mmHg in 70% of subjects with Raynaud's syndrome and in 3% of the controls. Local cooling from 30 to 10 degrees C during body cooling resulted in a significant mean decrease in pressure of over 40 mmHg in both groups (P less than 0.01) and the pressure fell below 30 mmHg in over 90% of the group with and in 26% of those without Raynaud's attacks. The results indicate the importance of body cooling and local temperature in the mechanism of vasospasm in the toes. They are also relevant to the diagnosis of Raynaud's syndrome in the lower limbs and have implications for the testing of patients with arteriosclerotic occlusion since erroneously low pressure values could be obtained in tests when the feet are cold.

Digital artery calibre measurement--a new technique of assessing Raynaud's phenomenon

This study evaluated the use of a high frequency A-mode ultrasound scanner (CUTECH DM70) for monitoring the digital artery vasospasm of Raynaud's Phenomenon (RP). The technique was evaluated on 12 RP patients and 12 age and sex matched controls. The diameter of a single digital artery was measured in these subjects over a range of finger temperatures between 14-35 degrees C. The reproducibility of the measurements was assessed by repeating the procedure in two subjects (a control and an RP patient) on 5 separate days. The results confirmed that the technique is reproducible and monitored vasospasm occurring in all 12 RP patients. In the temperature range tested, none of the controls developed digital artery vasospasm. At finger temperatures greater than 25 degrees C the response to thermal stimuli of the digital arteries in RP patients and controls was similar. However, at temperatures less than 25 degrees C a marked vasoconstriction leading to complete digital artery closure was seen in the RP patients and not in the controls. This technique may prove useful in monitoring RP patients.

Blood pressure levels and variance assessed by ambulatory monitoring: optimal parameters

We obtained multiple ambulatory blood pressure monitoring (ABPM) records over five years from two trained, normotensive subjects experienced in wearing the apparatus. The resulting time series data on systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were used to suggest optimal parameters for monitoring by two instruments (Colin Medical Instruments ABPM-630 and Del Mar Avionics Pressurometer) and to compare two indirect methods (auscultatory and oscillometric). A 10-min sampling interval day and night provided sufficient density of data to support spectral analysis for ultradian rhythms in the frequency range of one cycle per hour to one cycle per 9 h on a 24-h record. Rhythms with major periods of approximately 3, 6, and 9 h were variously found in 94 normotensive subjects, aged 20 to 95 years, including the two trained subjects. When the monitoring period was extended to 72 h, the circadian (approximately 24 h) rhythm could be more sharply defined, as well as a 12-h harmonic. In some studies the two trained subjects wore two monitors, one on each arm, set to read simultaneously. From the simultaneous measurements on both arms, it was shown that averaging across three points (30 min of record) reduced the coefficient of variation between the two simultaneous records to 6% or less. Auscultatory and oscillometric methods were equally reliable. Echocardiographic data were obtained in five normotensive subjects and compared to their ABPM data. The ABPM records provided additional information about cardiovascular function not merely duplicating that obtained by acute stress tests, such as exercise or cold pressor responses, or echocardiography. Standards for ABPM are suggested.