Subodh Arora

Differences in Foot and Forearm Skin Microcirculation in Diabetic Patients With and Without Neuropathy

OBJECTIVE We have compared the hyperemic response to heat and the endothelium-dependent and endothelium-independent vasodilatation between the dorsum of the foot and the forearm in diabetic neuropathic and non-neuropathic patients and healthy control subjects. RESEARCH DESIGN AND METHODS We studied the cutaneous microcirculation in the forearm and foot in 15 diabetic patients with neuropathy, in 14 diabetic patients without neuropathy, and in 15 control subjects matched for age, sex, BMI, and in the case of diabetic patients, for the duration of diabetes. Patients with peripheral vascular disease and/or renal impairment were excluded. The cutaneous microcirculation of the dorsum of the foot and the flexor aspect of the forearm was tested in all subjects. Single-point laser Doppler was employed to measure the maximal hyperemic response to heating of the skin to 44°C and laser Doppler imaging scanner was used to evaluate the response to iontophoresis of 1% acetylcholine chloride (Ach) (endothelium-dependent response) and 1% sodium nitroprusside (NaNP) (endothelium-independent response). RESULTS The transcutaneous oxygen tension was lower in the neuropathic group at both foot and forearm level, while the maximal hyperemic response to heat was similar at the foot and forearm level in all three groups. The endothelium-dependent vasodilation (percent increase over baseline) was lower in the foot compared to the forearm in the neuropathic group (23 ± 4 vs. 55 ± 10 [mean ± SEM] P < 0.01)], the non-neuropathic group (33 ± 6 vs. 88 ± 14; P < 0.01), and the control subjects (43 ± 6 vs. 93 ± 13; P < 0.001). Similar results were observed during the iontophoresis of NaNP (P < 0.05). No differences were found among the three groups when the ratio of the forearm:foot response was calculated for both the endothelium-dependent (neuropathic group, 2.25 ± 0.24; non-neuropathic group, 2.55 ± 0.35; and control subjects, 2.11 ± 0.26; P = NS) and endothelium-independent vasodilation (neuropathic group, 1.54 ± 0.27; non-neuropathic group, 2.08 ± 0.33; and control subjects, 2.77 ± 1.03; P = NS). The vasodilatory response, which is related to the C nociceptive fiber action, was reduced at the foot level during iontophoresis of Ach in the neuropathic group. In contrast, no difference was found during the iontophoresis of NaNP at the foot and forearm level and of Ach at the forearm level among all three groups. CONCLUSIONS In healthy subjects, the endothelial-dependent and endothelial-independent vasodilatation is lower at the foot level when compared to the forearm, and a generalized impairment of the microcirculation in diabetic patients with neuropathy preserves this forearm-foot gradient. These changes may be a contributing factor for the early involvement of the foot with neuropathy when compared to the forearm.

Lower extremity arterial reconstruction in the very elderly: Successful outcome preserves not only the limb but also residential status and ambulatory function ☆ ☆☆ ★

PURPOSE The purpose of this study was to evaluate our results with lower extremity arterial reconstruction (LEAR) in patients 80 years of age or older and to assess its impact on ambulatory function and residential status. METHODS We performed a retrospective review of all patients 80 years of age or older undergoing LEAR at a single institution from January 1990 through December 1995. Preoperative information regarding residential status and ambulatory function was obtained from the hospital record and vascular registry. Telephone interviews with patients or next of kin were undertaken to provide information regarding postoperative residential status and ambulatory function. Residential status and level of ambulatory function were graded by a simple scoring system in which 1 indicates living independently, walking without assistance; 2 indicate living at home with family, walking with an ambulatory assistance device; 3 indicates an extended stay in a rehabilitation facility, using a wheelchair; and 4 indicates permanent nursing home, bedridden. Preoperative and postoperative scores for both residential status and ambulatory function were compared. Kaplan-Meier survival curves were generated for graft patency, limb salvage, and patient survival. RESULTS Two hundred ninety-nine lower extremity bypass operations were performed in 262 patients 80 years of age or older (45% men, mean age 83.6 years, range 80 to 96 years). Sixty-seven percent of the patients had diabetes mellitus. Limb salvage was the indication for operation in 96%. The preoperative mean residential status and ambulatory function scores were 1.79+/-0.65 and 1.55+/-0.66, respectively. The perioperative mortality rate at 30 days was 2.3%. The median length of hospital stay decreased from 16 days in 1990 to 8 days in 1995 (range 4 to 145 days). Eighty-seven percent of grafts were performed with the autologous vein. The 5-year primary, assisted primary, and secondary graft patency rates for all grafts were 72%, 80%, and 87%, respectively. The limb salvage rate at 5 years was 92%. The patient survival rate at 5 years was 44%. The postoperative residential status and ambulatory function scores were 1.95+/-0.80 and 1.70+/-0.66, respectively. Overall scores remained the same or improved in 88% and 78% of patients, respectively. CONCLUSION LEAR in octogenarians is safe, with graft patency and limb salvage rates comparable to those reported for younger patients. LEAR preserves the ability to ambulate and reside at home for most patients.

Estrogen improves endothelial function

PURPOSE To determine the effect of estrogen on endothelium-dependent relaxation in the cutaneous microcirculation of women. METHODS Three groups of women participated in the study. Group 1 (n = 20) was premenopausal and had a mean age of 39 years (range 24-50 years). Group 2 (n = 9) was postmenopausal and had a mean age of 58 years (range 53-65 years). Group 3 (n = 11) was postmenopausal and taking estrogen replacement therapy; the mean age was 53 years (range 43-58 years). Eleven women in group 1 underwent testing twice, once during menstruation (mean serum estradiol level 73 +/- 30 pg/ml) and once during midcycle (mean serum estradiol level 268 +/- 193 pg/ml; p = 0.003). Single-point laser Doppler ultrasound and laser Doppler imaging with a scanner were used to measure vasodilatation in the forearm skin in response to iontophoresis of 1% acetylcholine (endothelium dependent) and 1% sodium nitroprusside (endothelium-independent smooth muscle relaxant). RESULTS All three groups were matched for body mass index and fasting glucose, total, high-density lipoprotein, and low-density lipoprotein cholesterol and triglyceride levels. All women had normal blood pressure, and none smoked. Mean serum estradiol levels were 196 +/- 170 pg/ml (group 1), 35 +/- 12 pg/ml (group 2), and 107 +/- 78 pg/ml (group 3) (p = 0.004). Maximum microvascular vasodilatation (percentage increase over baseline) in response to acetylcholine was reduced in group 2 (93% +/- 43%) compared with group 1 (187% +/- 63%) and group 3 (142% +/- 56%) (p = 0.001). The response to sodium nitroprusside also was diminished in group 2 (73% +/- 27%) compared with group 1 (126% +/- 45%) and group 3 (100% +/- 32%) (p = 0.02). Within group 1 the acetylcholine response was higher during the midcycle phase (186% +/- 31%) compared with the menstrual phase (147% +/- 57%) (p < 0.05). The sodium nitroprusside response also was higher during the midcycle phase (144% +/- 31%) compared with the menstrual phase (94% +/- 41%) (p < 0.05) CONCLUSION The results indicate that estrogens might enhance endothelium-dependent and endothelium-independent vasodilatation in the microcirculation of women.

Functional outcome in the elderly following lower extremity amputation

Data regarding functional outcome in the elderly following major lower extremity amputation (LEA) are minimal. In the general diabetic population there is a significant mortality associated with these procedures, with the 5-year survival rates approaching only 40%. Contrasts between this group and the nondiabetic population will help to clarify the morbidity of these procedures and substantiate efforts at limb salvage. The authors review their experience with patients 80 years of age and above undergoing major LEA between 1990 and 1995 with a specific focus on postoperative mortality and functional status. Forty-one patients were studied, 67% of whom had diabetes mellitus. Postoperative functional status remained unchanged in 40% and worsened in 55% of patients, while residential status was unchanged in 68% and worsened in 32%. The median survival for patients with and without diabetes was 19 and 49 months, respectively. The 5-year survival for the entire group was 25% and was not statistically different in the two subgroups. The authors conclude that major LEA in the very elderly is associated with a considerable mortality and deterioration of functional and residential status.

LOWER EXTREMITY MACROVASCULAR DISEASE IN DIABETES

Lower extremity macrovascular disease is more common and progresses more rapidly in the presence of diabetes and has a characteristic peritibial distribution with sparing of the foot arteries. The biology of the diabetic foot is compromised, thereby making it more susceptible to injury. Hence, compromises in perfusion have a greater significance, warranting an aggressive approach to revascularization.

Light reflection rheography: A simple noninvasive screening test for deep vein thrombosis

PURPOSE The clinical diagnosis of deep vein thrombosis (DVT) is unreliable. Contrast phlebography (CP) continues to be the gold standard, but it is invasive. Although duplex ultrasonography is an accurate, noninvasive alternative, it is expensive, technically demanding, and time-consuming. We postulated that light reflection rheography (LRR), a noninvasive method of assessing the quantity and rate of venous emptying, might be a reliable and inexpensive bedside approach to screening patients with clinically suspected DVT. METHODS With LRR, infrared light is beamed onto the skin, and the amount of backscattered rays are detected, which indirectly measures the amount of blood present in a volume of the epidermis beneath the LRR probe. Applied to the calf muscle pump, LRR can provide a noninvasive method of assessing blood volume changes in the sample area of skin, in response to venous hemodynamic changes in the lower limb. RESULTS Sixty-nine limbs in 61 patients undergoing CP for clinically suspected DVT over a period of 12 months also underwent LRR, either just before or within 24 hours of undergoing phlebography. The criteria for diagnosing DVT on CP were presence of filling defect or nonfilling of a venous segment. The result of LRR was considered positive for DVT if the rate of venous emptying was 0.35 or less. With these criteria a sensitivity of 96.4% and specificity of 82.9 were obtained. This resulted in a positive predictive value of 79% and a negative predictive value of 97.1%. CONCLUSIONS LRR is a simple, inexpensive, and noninvasive bedside test that takes 10 minutes to perform. It is highly sensitive with a high negative predictive value, detecting most cases of DVT, reliably ruling out DVT, and eliminating the need for more time-consuming and costly studies. Therefore it seems to be an appropriate screening test in patients with clinically suspected DVT.

Reactive hyperemic response of the brachial artery: Comparison of proximal and distal occlusion

RATIONALE AND OBJECTIVES The authors compared the postocclusion hyperemic responses of the brachial artery after occluding blood flow proximal to and distal to the studied area. MATERIALS AND METHODS Response of the brachial artery to hypoxia was evaluated with duplex Doppler ultrasound in 13 healthy subjects. A pneumatic tourniquet was first positioned 2-5 cm superior to the left elbow, proximal to the area of artery studied. Two hours later the response was remeasured with the tourniquet positioned 2-5 cm inferior to the elbow, distal to the artery studied. Arterial diameter, mean and peak flow velocities, and heart rate were assessed. RESULTS No significant differences were observed between measurements of baseline and postischemic arterial diameter, percentage diameter change, baseline mean arterial blood flow velocity, baseline peak arterial blood flow velocity, or postischemic heart rate obtained with proximal occlusion of the artery and those obtained with distal occlusion. In contrast, mean and peak postischemic arterial blood flow velocity and preocclusion heart rate were higher in measurements made during proximal artery occlusion. Significant correlation was found between measurements of percentage change in artery diameter obtained with proximal artery occlusion and those obtained with distal occlusion (r = 0.611, P < .05). CONCLUSION There are no major differences in postischemic changes in brachial artery diameter related to reactive hyperemia between blood flow occlusion applied proximal and distal to the studied area. However, there are significant differences in the mean and peak systolic velocities. Either occlusion site can be used for clinical studies if arterial diameter change is monitored, but if velocity measurements are being compared, a single occlusion site should be chosen.

Non-invasive impedance analysis : A new non-invasive test for graft surveillance

Detection of failing grafts with early reoperation is clearly associated with better long-term patency than intervention after graft failure. Duplex ultrasonography is more accurate than ankle:brachial index for graft surveillance, but is expensive, time consuming and technically demanding. Non-invasive estimation of graft impedance is now possible. The present study was undertaken to evaluate the utility of non-invasive impedance in detecting the failing vein graft. Sixty-nine grafts in 51 patients were followed over a period of 12 months (April 1992-March 1993). High risk infrainguinal arterial vein bypass patients were entered into a graft surveillance program. Ankle:brachial index, non-invasive impedance and duplex ultrasonography were performed upon discharge, 1 month after surgery and then at 3-monthly intervals. Non-invasive impedance was measured using a mean Doppler flow signal obtained from both upper and lower ends of the graft paired with the mean pulse volume recording obtained from the distal arterial bed. The mean pulse volume recording and flow signals were digitized by discrete Fourier transform and an impedance index generated. An impedance index > or = 0.5 was considered abnormal. Impedance results were compared with ankle:brachial index, duplex ultrasonography and angiography when appropriate, and detected 28 failing and five failed grafts. Non-invasive impedance achieved a sensitivity of 91% and a specificity of 94%. Similarly, duplex ultrasonography was 91% sensitive and 97% specific, while ankle:brachial index was 58% sensitive and 94% specific. Non-invasive impedance is a simple, inexpensive and effective test which detects the failing graft and is an appropriate first-line alternative to duplex ultrasonography for postoperative graft surveillance.