The influence of ulnar nerve blockade on skin microvascular blood flow*

Abstract

Abstract. Microvascular research is seriously ham pered by the great temporal and spatial variability of the measured skin blood flow and variation in sympa thetic vasomotor reflexes within and between persons. Therefore skin vasomotor reflexes were studied before and after ulnar nerve blockade within the same person, resulting in a temporal complete denervation of the fifth finger and partial denervation of the fourth finger. Skin temperature and laser Doppler flux (LDF) were registrated to measure predominantly arteriove nous shuntflow. Measurements were performed on the palmar tip of the second and fifth finger in nine healthy volunteers, at baseline, and during a sympa thetic reflex test (i.e. inspiratory gasp) and postural response test. Beat-to-beat digital blood pressure was recorded from the third and fourth finger by a Finapres device. Baseline capillary blood cell velocity (CBV) was measured at the nailfold of the second and the fifth finger. After ulnar blockade baseline skin temperature, LD F and CBV increased significantly, with respectively (mean ± SE) 3*2±0*9°C, 20*9 ±5*9 relative perfusion units and 0*79 ±0*40 m m " 1 s. The percentage LDF decrease of the fifth finger during inspiratory gasp was 48*2 ±5*3% before and 3*1 ±0-9% after blockade. The postural response test showed a decrease in LDF of the fifth finger with no significant difference before and after block ade, respectively 12*3 ±14*7% and 8*0±2*7%, while no difference was found in the increase in digital blood pressure in the denervated fourth finger compared to both the same finger before blockade and to the third non-blocked finger. It is concluded that ulnar nerve blockade enables the study of sympathetic skin vasomotor reflexes by comparison of a denervated and a non-denervated vascular bed within the same person. After ulnar blockade arteriovenous shunt flow as well as nutritional capillary blood flow increased significantly. Postural vasoconstrictor response is not abolished by ulnar blockade, suggesting that local regulatory mechanisms are more important.

The effect of polyneuropathy on foot microcirculation in Type II diabetes

“…Furthermore, the most severe abnormalities were observed in patients with a history of a diabetic foot ulcer. The increased skin temperature in our patients with polyneuropathy is in line with an increase in thermoregulatory shunt blood flow, due to loss of sympathetic vasoconstrictor tone, as shown previously [7,14]. Thermoregulatory blood flow (laser doppler flux), which was measured on the dorsum of the foot, was not increased in our neuropathic patients, also in accordance to earlier observations [23].…”

“…The effect of polyneuropathy on supine capillary skin blood flow is less well studied. Others [4,7] observed an increased number of visible capillaries and an increased CBV after ulnar blockade in both healthy subjects and in neuropathic patients with Type I diabetes. In another study [5] of a mixed cohort of Type I and Type II diabetic patients with polyneuropathy, CBV was not altered; however, when the width of the erythrocyte column was taken into account, erythrocyte flux was increased.…”

“…thermoregulatory) and nutritive (i.e. capillary) blood flow [7]. In contrast to Type I diabetes, Type II diabetes is probably not associated with increased cutaneous blood flow or elevated capillary pressure [8], unless hypertension co-exists, as hypertension is associated with increased capillary pressure [9].…”

Skin vasomotor reflex responses in two contrasting groups of autonomic failure

“…A relationship between laser Doppler recordings of SkVR responses and direct intraneural recordings of skin sympathetic activity has been reported (Lundin et al 1990). SkVR responses require intact peripheral sympathetic nerves as shown by studies in surgically sympathectomised subjects (Bolton et al 1936;Rex et al 1998) and temporary nerve blocks (Netten et al 1995;Lehtipalo et al 2000). In PAF, the lesion site affects the peripheral, postganglionic autonomic nerves (Matthews 2002), which is the final common pathway involved in all SkVRs.…”

EMLA and Water Immersion Cause Similar Vasodilatation in Replanted Fingers

“…In 1936, Lewis et al was first to observe the dependency of water immersion wrinkling on intact peripheral nerve function from a case of median nerve transection with loss of wrinkling restricted to the median sensory nerve territory [24]. Using ulnar nerve blockade, resulting in a temporal complete denervation of the fifth finger and partial denervation of the fourth finger, Netten et al demonstrated that the percentage of laser Doppler flux decrease in the fifth finger during a sympathetic reflex test of inspiratory gasp was 48.2 Ϯ 5.3% before and 3.1 Ϯ 0.9% after blockade [25]. In our study, all of the control fingers showed a considerable decrease in blood perfusion and remarkable skin wrinkling both after water immersion and EMLA application.…”