A simple method for predicting survival of pedicled skin flaps before completely raising them

Abstract

Background:

Pedicled skin and fasciocutaneous flaps are commonly used in plastic surgery. Once such a flap is completely raised on its pedicle it becomes defenceless against any possible necrosis.

Aim:

To use a simple method for raising such a flap in a manner that can predict the vascularity better, offering additional protection against necrosis.

Materials and Methods:

A total of 30 skin and fasciocutaneous flaps were raised in 27 patients. They were raised as bipedicle flaps; and the vascularity of the flap was tested by occluding the additional pedicle with a pedicle occlusion clamp. If the vascularity was found to be satisfactory the flap was primarily transferred; if found unsatisfactory it was either delayed or abandoned. The delayed flaps were again tested during transfer.

Results:

Nineteen (63.3%) flaps were primarily transferred, 11 (36.7%) flaps were delayed, and two (6.7%) delayed flaps displayed an unsatisfactory pattern during transfer. Twenty-two (73.3%) flaps fully survived and seven (23.3%) underwent partial thickness necrosis at the tip, which healed without any further surgical intervention, making 29 (96.7%) flaps clinically successful. There was major necrosis of one flap. All the flaps with a scar at the base survived.

Discussion:

The clinical success of 96.7% indicated a high-degree of predictability of flap survival through this method. Also, this method could safely assess the vascularity of flaps during primary transfer, during delayed transfer, and also those with a scar at the base.

Conclusions:

This technique is recommended in all major pedicled skin and fasciocutaneous flaps.

INTRODUCTION

The conventional method of testing the viability of a pedicled skin or fasciocutaneous flap is to completely raise it on its pedicle and then assess the vascularity at its tip. Despite preoperative planning many flaps undergo necrosis, which cannot be easily prevented at this stage. A simple method has been used to predict the vascularity of such a flap intraoperatively, thereby increasing the success of skin and fasciocutaneous flaps. Only if the falps passed this test of temporary vascular occlusion at the distal end were they thought worthy of primary transfer.

MATERIALS AND METHODS

This study was performed in a medical institute. The ethical clearance was taken from the institute ethical committee. The technique was used with 30 pedicled skin and fasciocutaneous flaps in 27 patients over a period of 22 months between September 2006 and July 2008. Twenty-four (88.9%) were male and three (11.1%) female. The age ranged from 14 to 60 years, the median being 32. Twenty-five (83.3%) were fasciocutaneous flaps and five (16.7%) were skin flaps. Both superiorly and inferiorly based flaps were raised. The maximum length to breadth ratio of the fasciocutaneous flaps was 3:1 and of the skin flaps 1.5:1. Three (10%) of the flaps had a scar at the base.

A pedicle occlusion clamp containing two stainless steel plates with opposing flat surfaces and blunt margins, with facilities for tightening the flap with nuts and bolts, was used.[1]

An atraumatic Kocher's intestinal clamp was used on two occasions.

The surgery is performed under tourniquet. To cover a defect [Figure 1] the flap is marked as a bipedicle flap [Figure 2]. It contains the proposed pedicle and the additional pedicle that is located either at the opposite end or on one side of the flap, keeping an extra length of 1 cm beyond the additional pedicle to accommodate the clamp [Figure 2]. The tourniquet is released, and a return of vascularity to the flap is confirmed by the presence of a bright red blood ooze after making stab incisions using a No-11 blade over the centre and both ends of the flap [Figure 3]; the clamp is applied and tightened on the flap just beyond the additional pedicle [Figure 4]; exsanguination of the flap is done by rolling a mop thrice over the flap, toward the proposed pedicle, in a gentle manner [Figure 4]; and immediately following the exsanguination the future tip is stabbed at the centre and two sides for testing reperfusion. The presence of at least one drop of bright red colored blood on each of the three points [Figure 5] is considered as satisfactory vascularity in which case the additional pedicle is divided and the flap is primarily transferred, while taking care not to include the clamped skin. Absent, scanty or dark ooze over any of the three points is considered unsatisfactory, in which case the flap is either delayed or abandoned by removing the clamp and leaving the flap in its bipedicle state. The delayed flaps are tested in the same manner as at the time of transfer. The survival of the flaps is assessed postoperatively, minimum after 48 hours and during follow-up [Figure 6], either through the stab test or through the appearance of the flap.

Figure 1.

Intraoperative view showing post-release defect of burn contracture (L) elbow

Figure 2.

Intraoperative view of a superiorly based fasciocutaneous flap marked in a bipedicle manner. Arrow points to the extra incision for application of the clamp

Figure 3.

Intraoperative view following release of tourniquet. The raised bipedicle flap showing bright red ooze all over, confirming return of vascularity

Figure 4.

Intraoperative view showing the tightened clamp and the process of exsanguinations of the flap

Figure 5.

Intraoperative view showing bright red blood ooze at all the three stab points, at the future tip

Figure 6.

Four months follow-up view showing complete survival of the flap

If necessary, the clamp can be applied on the side of the flap [Figure 7].

Figure 7.

Intraoperative view of an inferiorly based fasciocutaneous flap from the (L) forearm, with clamp applied on the side, with the tip showing a satisfactory bleeding pattern

RESULTS

The pattern of bleeding was satisfactory in 19 (63.3%) flaps, which were primarily transferred; it was unsatisfactory in 11 (36.7%) flaps, which were delayed and transferred later after retesting their vascularity in the same manner [Figure 8]. Two (6.7%) flaps showed an unsatisfactory bleeding pattern at the tip during the delayed transfer [Figure 9]. They were transferred after shortening their tips by 2 cm, while ensuring cover of the critical area. None of the flaps was abandoned. Twenty-two (73.3%) flaps fully survived and seven (23.3%) underwent partial thickness necrosis at the tip, which healed spontaneously, serving the purpose, without affecting the result. Thus, 29 (96.7%) flaps were clinically successful. One (3.3%) flap underwent full thickness necrosis of the distal third warranting a second flap; and, hence, was considered a clinical failure. There was no necrosis in any of the flaps during the delay period. All the three flaps with a scar at the base survived [Figure 10]. It was observed that all the satisfactory bleeding patterns at the tip appeared within five seconds during reperfusion. In all unsatisfactory cases either the bleeding did not appear at all or took more than 20 seconds to appear. There was no necrosis of the clamped skin.

Figure 8.

(a) Intraoperative view of the inferiorly based fasciocutaneous flap, showing dark ooze at all the points of the future tip, at primary assessment. The flap was delayed. (b) Intra-operative view during delayed transfer showing a satisfactory bleeding pattern at the tip of the delayed flap. (c) 25 days post-operative view showing full flap survival

Figure 9.

(a) Pre-operative view showing exposed olecranon (L) elbow. (b) Intra-operative view of delayed superiorly based fasciocutaneous flap showing absence of bleeding at the future tip. (c) The flap was divided 2 cm proximally where the arrow points. (d) Two months follow-up view showing healed flap covering the critical area

Figure 10.

(a) Pre-operative view of the (L) foot with exposed bone. (b) Intra-operative view of superiorly based skin flap with a scar at base, where the arrow points, showing satisfactory bleeding at the future tip. (c) Follow-up view showing full survival of the flap

DISCUSSION

The conventional teaching of following a certain length to breadth ratio in a random pattern pedicle skin flap is fallacious.[2] The survival of an axial pattern skin flap also extends beyond the anatomical limit of the artery supplying it.[3]

Skin flap dimension depends on several factors, namely, calibre and length of the dominant vessel on which the flap is based; the calibre and span of the adjacent captured artery or arteries; the caliber and length of the connecting choke vessels and the anatomical favourability of the venous return.[4]

It is not possible, preoperatively, to assess so many variables at present. A better way is to predict the vascularity by assessing it on the basis of the clinical presence of vascularity, as in the present method.

This principle of assessing vascularity, in a modified form, is practised, at times, on perforator-based island flaps, when the flap is raised, keeping two vascular pedicles, and then the better one is chosen after clamping them alternately and testing the vascularity of the flap.[5]

To prevent necrosis in a long flap, the procedure of delay, as advocated by Blair,[4] in 1921, is generally adopted. However, there are many questions to be addressed. One: Whether the time delay in flap coverage is acceptable in given situation? Two: Whether the delay is actually necessary? Three: Whether the delayed flap will have adequate vascularity? The present method offers a solution to all these problems by directly assessing the clinical presence of vascularity before delaying the flap.

There are many methods of testing the vascularity of the flaps. Test of dermal bleeding through pricks is a simple and effective clinical test[6] and that is the reason why it is employed. The testing of bleeding on both the pedicles and the centre of the flap, before application of the clamp, was to ensure that there was return of perfusion and absence of vasospasm over the entire flap following release of the tourniquet. Single point testing of the flap vascularity may be unreliable, hence the authors have always performed vascularity assessment at three points.

All the flaps were exsanguinated to avoid misleading ooze of the accumulated blood. During reperfusion, bleeding at the tip within five seconds was always satisfactory, If it was delayed beyond twenty seconds it was always unsatisfactory, The observation that successful reperfusion occurred within five seconds following exsanguination was comparable to Allen's test[7] on hand.

Out of the total 30 flaps, 22 fully survived and seven, although they had partial thickness necrosis, healed spontaneously, serving the purpose, without either needing a second flap or compromising the result. Thus, clinical success was achieved in 29 (96.7%) flaps. This high success rate could be attributed to the technique used.

There was full thickness necrosis in one flap, which was a primarily transferred, thin, distant skin flap in an uncooperative patient, who did not maintain the position, causing tension on the suture line of the flap. The cause of partial thickness necrosis of the tip in some flaps, despite the presence of clinical, satisfactory intraoperative vascularity, was probably due to focal post-traumatic ischaemia, as most of the cases had trauma. All the flaps with a scar at the base survived. This was because either the scars were not deep or they did not affect the vascularity of the flap. Temporary clamping of the pedicle did not produce flap necrosis. However, the clamped skin was not used at the tip in any of the flaps, excepting in one, as minor damage to the vascularity could lead to necrosis in this critical area.

The advantages of this technique are:

1. This is a simple and safe technique for assessing the vascularity of a pedicled skin or fasciocutaneous flap intraoperatively, which offers extra protection to the flap from necrosis. It allows raising a flap of a size dictated by the need rather than by the anatomical studies.

2. It is a practical way of assessing vascularity of a long flap for primary transfer thus avoiding a delay, at times.

3. It can identify a flap, which needs delay, but otherwise would have passed as a safe flap and would have undergone necrosis after raising it.

4. It helps in assessing the vascularity of a delayed flap and a flap with scar at the base.

The disadvantages of the technique are the following:

1. It takes a few minutes of extra time to raise this flap.

2. Additional incisions are necessary to place the clamps.

CONCLUSIONS

The present technique is a simple method for assessing the vascularity of pedicled skin and fasciocutaneous flaps intraoperatively, which provides additional protection to them from the undergoing necrosis; it allows to safely test the vascularity of long flaps; and can safely be used to test the vascularity of a flap with a scar at the base. This is recommended in all pedicled skin and fasciocutaneous flaps.