Transkutaneus 7

Scand J Plast Reconstr Hand Surg 24: 129-134, 1990

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EFFECTS OF ELECTRICAL NERVE STIMULATION (ENS) IN ISCHEMIC TISSUE J. Kjartansson',2 and T. Lundeberg3 From the 'Department of Surgery, St. Joseps Hospital, Hufnarfjordur, Iceland, 'Department of Plastic and Reconstructive Surgery, Kurolinska Hospital, and 'Physiology 11, Karolinska Institute, Stockholm, Sweden

(Submitted for publication November 10. 1988)

Abstract. Blood flow was measured in the skin flaps of 20 patients who had undergone reconstructive surgery. All flaps were showing clinical signs of deficient circulation. Local blood flow in skin flaps was significantly increased by electrical nerve stimulation (ENS) @
Key words: electrical nerve stimulation, ischemia, skin flaps.

After reconstructive surgery, ischemia may develop, causing tissue necrosis and treatment failure. There is at present no effective means of reversing, established tissue ischemia. We have shown in previous studies that electrical nerve stimulation and acupuncture may increase the peripheral blood flow (6, 12). These findings prompted us to study the effects of electrical nerve stimulation (ENS) in ischaemic skin flaps. PATIENTS AND METHODS Over a 28-month period 20 patients who underwent surgery with cutaneous or fasciocutaneous flaps were included in the study. Details are presented in Table 1. The average age was 52 years (range 29-64), and there were 15 women and 5 men. All flaps had slow capillary refill. Informed consent was obtained from all patients. The 20 patients were initially treated with ENS or placebo-ENS according to a randomized crossover scheme (Table 11). During the trials the patients were given either ENS treatment or placebo-ENS for one hour followed by a 6-10 hours rest period, after which the alternate trial mode was given. After the crossover trial the patients started on a therapeutic course of ENS for 2 hours twice a day until there was a significant improvement in the clinical signs of ischaemia. The ENS stimulator (TENS, DELTA, UK) produced monopolar square wave pulses, with a duration of 0.2

msec and a frequency of 90 Hz.The stimulus intensity was set to 4 times the perception threshold, which produced a strong tingling sensation in the stimulated area. Two rubber electrodes, measuring 3 cm x 4 cm, were positioned on the skin at the base of the area to be treated (Fig. I). Placebo procedure was identical except there was no electrical output to the electrodes. Before the crossover trial the patients were informed that the sensation they felt might vary from strong to none at all, but that it was unrelated to the effect of therapy. The cutaneous blood flow in the ischemic part of the flap, and in the corresponding area opposite, was measured continuously for 1 h before, during and after ENS and placebo treatments with a laser Doppler flowmeter, PF2, equipped with the measuring probe P F 103 d (Perimed, Stockholm, Sweden) (16). The frequency limit was set at 30 kHz and the gain control at x3. The blood flow is recorded linearly as the product of the encountered red blood cells and their mean velocity. The radiation penetrated the skin to a depth of 1-1.5 mm, measuring dermal capillaries and arteriovenous shunts. By using a probe holder the laser-probe was placed 4 mm above the skin surface resulting in a measured area of about 20 mm2. The recordings were camed out in a quiet room with an ambient temperature of 20°C. The blood flow was continuously registered on a chart-recorder as laser Doppler units (LDU, i.e. arbitrary units of measured blood flow. The Mann Whitney U-test was used for comparison of blood flow and clinical signs between the different groups.

RESULTS All 20 patients included in the present study showed signs of slow capillary refill, oedema and stasis. In the crossover trial 8 patients were randomized to start with placebo ENS and 12 with ENS. There was no significant difference in blood flow before treatment. ENS treatment resulted in a significant increase in blood flow (p
I30

J . Kjartansson and T . Lundeberg

Table I. A g e , sex, diagnosis and operative memiire qf' the 29 pritients tretited with electricd nerve stimulation ( E N S )

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I = face, II = trunk, 111 = lower extremity. A = fasciocutaneous flap, B = cutaneous flap No.

Sex

Age

Diagnosis

Region and reconstructive meawre

1 2 3 4 5 6 7 8 9 10 11 12 13 14 I5 16

M F F M M F F F F F M F F F F F F F F M

43 47 60 49 48 52 32 41

Subcutaneous tumor Subcutaneous tumor Skin tumor Subcutaneous tumor Subcutaneous tumor Subcutaneous tumor Mammary hyperplasia Mammary hyperplasia Mammary hyperplasia Mammary hyperplasia Mammary hyperplasia Mammary carcinoma Mammary carcinoma Mammary carcinoma Mammary carcinoma Mammary carcinoma Mammary carcinoma Avulsion trauma Avulsion trauma Avulsion trauma

II A II A IB II B I1 A II A 11 B 11 B II B II B II B II A I1 A 11 B II A I1 A I1 A Ill B 111 B 111 B

17

IR 19 20

53 28 33 57 40 43 46 64 49 29 32 44

therapeutic course of ENS (Fig. 2 ) . Measurements on the 3rd day before the 6th application showed that blood flow had improved significantly @<0.001) (Table 111). After the sixth session of ENS there was a further increase in blood flow @<0.005) in 16 of the patients. The clinical picture, i.e. capillary refill, stasis and oedema was assessed on the third day of treatment and compared with the clinical picture after surgery (Table IV). The results show significant improvement @
Table 11. Ejfects of ENS and placebo-ENS on peripheral blood flow in ischaemic surgical f l a p s Peripheral blood flow assessed with laser Doppler flowmetry as laser Doppler units (LDU. i.e. arbitrary units of measured blood flow). Recordings of peripheral blood flow before placebo-ENS (BPE), during placebo-ENS (DPE), after placebo-ENS (APE), before ENS (BE), during ENS (DE) and after ENS (AE). The Mann Whitney U test (two-tailed) was used for comparison of blood flow between groups Sample

No.

BPE DPE APE BE DE AE

20 20 20

20 20 20

Median 4.00 5.00 6.00 6.00 14.00 15.50

Variance 19.63 26.79 18.34 23.21 94. I 6 8 I .08

Statistical analysis

BPE BPE BPE BPE BPE BE BE DE

VS.

vs. vs. vs . vs. vs. vs. vs.

DPE APE BE DE AE DE AE AE

NS NS NS p
NS

Electrical nerve stimulation in ischemic tissue

Table IV. Clinical picture before ENS treatment and after 3 days of ENS treatment

A

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\

Capillary refill was evaluated by 4 ranks: capillary refill after pressure 3 sec (+++). 3-6 sec ( + + I . 6 sec (+) and no refill (0). Stasis was evaluated by colour i n 4 ranks: normal skin colour (0). red (+), reddish blue ( + + ) and blue (+++). Oedema was evaluated by palpation in 3 ranks: no oedema (0). moderate oedema (+) and marked oedema (+ +). Stasis before treatment (SBT). capillary refill before treatment (CBT), oedema before treatment (OBT). stasis after treatment (SAT). capillary refill after treatment (CAT) and oedema after treatment (OAT). The Mann Whitney U-test (two-tailed) of the ranking score was used for comparison of clinical picture between the different groups

C

E

D

Sample

No.

Median

Variance

SBT CBT OBT SAT CAT OAT

20 20 20 20 20 20

2.00 0.00 1s o I .oo 2.00 1 .00

0.48 0.23 0.26 0.41 0.73 0.33

SAT CAT OAT

p<0.001 p
Statistical unalysis SBT vs. VS. CBT OBT vs.

Fig. 1 . Placement of electrodes used in the cutaneous flaps (A. B, E) and fasciocutaneous flaps (D.C).

Table 111. Peripheral bloodjlow in ischaemic surgical jlaps was as laser doppler units (LDU, i . e . arbitrary units of measured blood flow) after surgery (LAS), before ENS on the third day (BE) and after ENS on the third day (AE) The Mann Whitney U-test (two-tailed) was used for comparison of blood flow between the different groups Sample

No.

LAS BE AE

20 20 20

Statistical analysis LAS vs . LAS vs. BE vs .

Median 4.50 19.50

33.50

BE AE AE

131

Variance 21.11 122.17 247.88

p
there was epidermolysis and assessment with laser Doppler flowmetry showed an increase in blood flow from 0 to 40 arbitrary units. The flap healed after 10 days of treatment (Fig. 3). Case 5 . A 43-year-old woman operated for high risk mammary carcinoma had a subcutaneous mastectomy and reconstruction with a prosthesis. Reduction of the skin over the breast was also carried out. On the third postoperative day there were signs of stasis and oedema. Laser Doppler flowmetry showed no blood flow in the skin of the flap or at the distal part of the mamillae. After three days of ENS-treatment there was epidermolysis of the skin flap. All signs of stasis and oedema were gone and capillary refill had increased. Laser Doppler flowmetry showed an increased blood flow ( 5 4 5 arbitrary units). Treatment was continued for one week after the flap had healed (Fig. 4). DISCUSSION Experimental and clinical studies have shown that skin flaps showing no capillary refill or blood flow Sccind J Plost Rcconstr Hnnd Surg 24

-J . Kjartansson and T . Lundeberg

132

LDU

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8- -

30 20

1

l0I

0’. 0

Fig. 2. Effect of placeboENS (p) and electrical nerve stimulation(ENS) on peripheral blood flow as assessed with laser Doppler flowmetry on the distal part of the flap in the patients undergoing reconstructive surgery. LDU = laser Doppler arbitrary units.

--:

/

1

2

3

TENS

I

1

2

when measured with laser Doppler flowmeter at the distal part in most cases proceed to necrosis (4, 5, 11, 14). The present study shows that treatment with ENS (high intensity, high/frequency) increases blood flow in an ischemic surgical flap compared with placebo-ENS. The increased blood flow level correlates well with the long-term survival of the flap. The increase in blood flow generally started 10-15 min after the commencement of treatment. Repeated ENS treatments on consecutive days resulted in gradual improvement of the blood flow. In 16 of the 20 patients in this study, repeated ENS treatment significantly (p
3

HOURS

tape holding the electrodes in position. Two of these developed erythema. Contraindications to the use of ENS are the presence of pacemakers or other implanted electrical devices which may be affected by the electrical field of the stimulator (17). It should be noted that flaps initially benefitting from ENS treatment progressed to established necrosis if treatment was stopped too soon, suggesting that treatment should be continued for some time after healing seems complete. The results of the present study show that postoperative TENS treatment of ischemic flaps increases peripheral blood flow and may prevent necroses. So far no drugs appear to have a similar effect (3, 7, 8, 9, 19). Furthermore, ENS is easy to apply and has no undesired side effects. The findings indicate that ENS should be tried in ischemic surgical flaps.

Fig. 3 a , b and c. Case 3. A 60-year-old woman operated for a skin tumor located on the right side of the chin. ( a ) Flap 24 hours after surgery and before ENS treatment. (b) Flap 96 hours after surgery and after 6 ENS treatments (see Methods). (c) Flap three weeks after surgery and with daily ENS treatments. Scand I Plasr Reconstr Hand Surg 24

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Electrical nerve stimulation in ischemic tissue

133

Fig. 4 a , b and c. Case 5 . A 42-year-old woman operated for a mammary carcinoma with subcutaneous mastectomy. (a) Flap 72 hours after surgery and before ENS treatment. ( b ) Flap 96 hours after surgery and 6 ENS treatments (see Methods). (c) Flap three weeks after surgery and with daily ENS treatments.

One possible explanation for the increase in blood flow is the activation of sensory neurons mediated through large myelinated afferent nerve fibres which, in turn, activate local inhibitory circuits within the dorsal horn of the spinal cord (15). Such circuits may inhibit sympathetic transmission in the spinal cord. The arrangement of inhibitions mediated by A fibres is probably segmental. Polysegmental inhibitory circuits also exist, but they tend to require higher intensity stimuli to activate them since these inhibitory mechanisms are largely mediated by A delta and C afferents (1, 18). It has also been shown that high intensity stimulation induces antidromic activity in sensory nerve fibers, which may result in vasodilatation (13). This vasodilatation is assumed to involve substance P and calcitonin gene-related peptide (CGRP) (2, 10, 11, 12, 13). Thus the effects of ENS on flap survival may be due (a ) to a segmental inhibition of sympathetic vasoconstriction and (b) to the release of vasodilatory peptides from sensory neurons.

3.

4. 5. 6.

7.

8.

9. 10.

ACKNOWLEDGEMENTS This work was supported by the Torsten Nilsson Foundation. The assistance of Ms U. Lindgren in preparing the manuscript is gratefully acknowledged.

11.

12.

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mediated vasodilatation in hairy skin of the human foot. J Physiol 1987; 382: 105-121. 2. Brain SD, Williams TJ, Tippins JR, Moms HR, Mac

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electrical nerve stimulation. Heidelberg: SpringerVerlag, 1988. 18. Rowel1 LB. In: Vanhoutte PM, Leusen J , eds. Vasodilation. Active neurogenic vasodilation in man. New York: Raven Press, 1981: 1-18. 19. Wexler MR, Kalisman M, Yeschua R, Neuman Z. The effect of phenoxybenzamine, phentolamine and 6-hydroxydopamine on skin flap survival in rats. J Surg Res 1975; 19: 83-87.