A study of regional nerve blocks and local anesthetic creams (Prilox®) for donor sites in burn patients

Gupta, Amit; Bhandari, P.S.; Shrivastava, Prabhat

doi:10.1016/j.burns.2006.04.019

« Previous Next »Burns
Volume 33, Issue 1 , Pages 87-91, February 2007

A study of regional nerve blocks and local anesthetic creams (Prilox^®) for donor sites in burn patients

Department of Plastic Surgery, Lok Nayak Hospital, Delhi 110002, India

Accepted 17 April 2006.

Article Outline

Abstract
1. Background
2. Anatomy of nerve blocks
- 2.1.1. The lumbar plexus [2–6]
- 2.1.2. Lateral cutaneous nerve of the thigh
3. Materials and methods
- 3.1. Inclusion criteria
- 3.2. Exclusion criteria
4. Results
5. Discussion
6. Conclusion
References
Copyright

Abstract

Background

Burn patient requires multiple visits to the operation theatres and undergoing anesthesia with its attendant risks and post anesthesia recovery. It is possible now with the availability of local anesthetic creams like Prilox^® to conduct these procedures in the minor OT without any discomfort to the patient.

Materials and methods

Hundred patients of post burn raw areas were selected. These patients had at least one area of healthy skin on anterior, medial or lateral thigh. No patient had a known drug allergy. The age group varied from 5 to 75 years with no bias towards any sex. These patients were then given anesthesia according to the group, and were assessed for the ease of grafting, amount of graft being harvested, subjective pain score, post operative pain relief and any post operative complication. The nerve block technique being used was either femoral and/or LCT block or 3-in-1 block and popliteal fossa block.

Results

Both the group of patients had a virtual painless process of skin grafting. It is safe in selected patients to combine the two techniques in order to harvest larger areas.

Discussion

Both techniques of local anesthestic creams and nerve block are safe and convenient to use. Nerve blocks are more useful where larger grafts are required, the creams being more useful in children and where less graft is required.

Keywords: Burns, Prilocaine, Lignocaine, Nerve block

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1. Background

Burns is a devastating epidemic in India. Not only is it a huge financial drain on the patients family, it is a harrowing emotional and physical trauma to the patient and the treating surgeon. It necessarily commits the patient to a long follow-up, repeated procedures of grafting to cover the resultant areas of grafting, and subsequent visits for surgical treatment of contractures with subsequent long periods of rehabilitation. The burn patient requires multiple visits to the operation theatres and undergoing anesthesia with its attendant risks and post anesthesia recovery. It is possible now with the availability of local anesthetic creams like prilox, which is a mixture of prilocaine and lignocaine, available in other names, such as EMLA, to conduct these procedures in the minor OT without any discomfort to the patient. These creams allow local absorption of the anesthetic agent with blocking of nerve endings in the superficial layers of skin. However, these agents require time for action with periods ranging from 2 to 5h, and the areas which can be covered are also limited in view of possible toxicity.

Another technique of nerve blocks is available which allows a simple way to achieve large areas of anesthesia with single injection [1], [2]. These blocks are the femoral nerve block, the lateral cutaneous nerve of thigh (LCT) block and 3-in-1 block.

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2. Anatomy of nerve blocks

The nerve supply of the lower limb is derived from the lumbar and sacral plexuses, a network of nerves composed of the anterior primary rami of all the lumbar and the first three sacral nerve roots (and sometimes with a contribution from the 12th thoracic nerve root) [2].

2.1.1. The lumbar plexus [2], [3], [4], [5], [6]

This gives rise to the femoral nerve, obturator nerve and lateral cutaneous nerve of the thigh. The femoral nerve block has been nicely described [3], [4], [5], [6].

2.1.2. Lateral cutaneous nerve of the thigh

Supplies sensation to the skin over the lateral (outside) thigh, from the greater trochanter to the knee and on to the anterior thigh.

“Winnie 3-in-1 block” because it aims to block three nerves with the one injection: the femoral nerve, the lateral cutaneous nerve of the thigh and the obturator nerve [3], [4], [5], [6]. If local anaesthetic injected around the femoral nerve at the inguinal ligament can be made to spread proximally, then the other two nerves can be simultaneously blocked at their origins from the lumbar plexus.

The safe anesthetic dose of lignocaine is 3–7 management/kg (with adrenaline) [7].

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3. Materials and methods

Hundred patients were part of the study. These patients had post burn raw areas ranging from 1 to 15 percent of TBSA.

3.1. Inclusion criteria

(1)Post burn raw areas.

(2)Patients between 5 and 75 years of age.

3.2. Exclusion criteria

(1)History of drug allergy.

(2)Patients on other prior medications.

(3)Patients insisting for general anesthesia.

Hundred consecutive patients were distributed into the two groups after prior consent and explanation of both the procedures. In Group 1, Prilox^® was applied to the area from where graft was required. Cream was applied for 2

h at a concentration of 12.5

gm per 100

cm² area. The observations are tabulated in Table 1. In Group 2, the patients were planned for nerve blocks. There was a bias towards age distribution in this group with minimum age being 18 years. The local anesthetic used was lignocaine and adrenaline(1:200,000) at 5

mg/kg of body weight. After an average period of 15–20

min grafts were harvested. The results are tabulated in Table 2.

Table 1.

S no.	Age of patient	Amount of Prilox^® used in grams	Graft size (measured preoperative) cm	Pain analogue score (/10)	Duration of pain relief post operative (min)	Post operative complication
1	26	20	15×10	2	45	Nil
2	13	10	10×8	4	60	Nil
3	6	10	10×10	3	30	Nil
4	65	25	25×10	0	60	Nil
5	47	25	25×10	2	80	Nil
6	31	15	10×10	1	40	Nil
7	28	25	20×10	2	45	Nil
8	7	10	5×5	4	50	Nil
9	52	25	5×5	6	60	Nil
10	10	10	3×5	3	30	Nil
11	45	20	12×8	0	45	Nil
12	32	25	20×10	1	70	Nil
13	33	25	20×10	0	50	Nil
14	26	20	15×10	0	40	Nil
15	29	20	15×10	0	60	Nil
16	40	25	25×10	3	35	Nil
17	56	25	20×10	2	45	Nil
18	70	25	10×5	7	60	Nil
19	38	25	20×10	2	65	Nil
20	21	20	15×10	4	90	Nil
21	18	20	15×10	1	45	Nil
22	19	25	25×10	0	50	Nil
23	45	20	15×10	1	50	Nil
24	42	25	20×10	1	60	Nil
25	49	25	20×10	1	45	Nil
26	31	25	20×10	1	55	Nil
27	64	20	15×10	1	35	Nil
28	28	25	20×10	2	60	Nil
29	30	25	20×10	2	45	Nil
30	12	15	10×10	2	60	Nil
31	34	25	25×10	3	65	Nil
32	26	20	20×10	1	20	Nil
33	28	15	10×10	0	45	Nil
34	47	25	20×10	2	60	Nil
35	41	20	15×10	1	50	Nil
36	40	25	20×10	0	40	Nil
37	30	25	20×10	2	30	Nil
38	37	20	15×10	1	80	Nil
39	24	25	20×10	3	55	Nil
40	71	25	25×10	2	75	Nil
41	43	25	20×10	2	40	Nil
42	56	20	15×10	1	65	Nil
43	39	25	20×10	1	40	Nil
44	51	25	20×10	0	50	Nil
45	22	25	20×10	0	60	Nil
46	27	20	15×10	3	45	Nil
47	52	25	20×10	2	50	Nil
48	9	15	10×10	1	45	Nil
49	35	15	10×5	1	50	Nil
50	40	20	15×10	5	60	Nil

Table 2.

S no.	Age	Block (s) used	Graft size (measured preoperative)	Pain analogue score (/10)	Duration of pain relief post operative (min)	Post operative complication
1	20	F	15×10	0	160	Nil
2	39	F, LCT	20×10, 10×10, 10×5	2	200	Nil
3	47	F	25×10	1	180	Nil
4	65	F	25×10	0	200	Nil
5	73	F	25×10	0	100	Nil
6	25	F	15×10	0	230	Nil
7	45	F	10×5	0	110	Nil
8	65	F	5×5	4	190	Nil
9	23	F/LCT	20×10, 10×10	2	110	Nil
10	26	LCT	20×10	3	90	Nil
11	40	LCT	10×10	1	125	Nil
12	21	F, LCT	25×10, 20×10	1	130	Nil
13	32	S	15×10	1	100	Nil
14	37	F	10×10	1	60	Nil
15	34	LCT	10×10	5	160	Nil
16	29	PF	12×8	0	100	Nil
17	18	F, LCT	15×10, 15×10	2	90	Nil
18	32	F	10×10	2	150	Nil
19	26	F	15×10	2	160	Nil
20	49	F	15×10	2	135	Nil
21	63	F, LCT	10×5, 10×5	3	160	Nil
22	50	F, LCT, +pri (15 grams)	20×10, 15×5, 5×5	1	125	Nil
23	60	F	5×5	1	110	Nil
24	24	F	10×10	1	90	Nil
25	51	F/LCT	10×10, 10×10	1	95	Nil
26	18	PF	10×5	1	100	Nil
27	20	F	10×10	0	185	Nil
28	21	F	20×10	0	145	Nil
29	43	F	15×10	0	160	Nil
30	34	F	25×10	0	125	Nil
31	35	F	25×10	0	100	Nil
32	38	F	25×10	2	90	Nil
33	30	F, +pri (15 grams)	8×5, 10,10	4	120	Nil
34	20	F/LCT	25×10, 15×10	3	120	Nil
35	21	F	25×10	2	130	Nil
36	54	F, LCT	25×10, 20×10	3	120	Nil
37	65	F	15×10	3	110	Nil
38	24	F	8×10	2	100	Nil
39	48	F	5×8	1	95	Nil
40	49	F, LCT	10×10, 5×5	0	150	Nil
41	36	F, LCT	15×10, 10×10	1	140	Nil
42	38	F	20×10	1	135	Nil
43	35	F	15×10	1	150	Nil
44	41	F	10×10	2	100	Nil
45	21	F, LCT	10×10, 15×10	2	120	Nil
46	23	F, LCT	25×10, 20×10	2	145	Nil
47	27	F	25×10	0	185	Nil
48	29	F, +pri	15×10, 10×10	2	100	Nil
49	32	F	25×10	0	60	Nil
50	33	F/LCT	25×10	1	100	Nil

F, femoral block; LCT, Lateral cutaneous nerve of thigh; PF, popliteal fossa block; S, sciatic block; +pri, block +Prilox^®.

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4. Results

In Group 1, the average post operative analgesia is 51.8min with a range of 30–90min. The graft size taken was a factor of the amount of the cream applied. There was no post operative problem or complication.

In Group 2, there is a noticeable bias towards grouping of patients where larger grafts are required. Most patients in this group were those where more than one sheet or larger sheets were harvested. In two patients, Prilox^® was also used, as virgin skin was short, and patches of skin were available on posterior thigh. In the patients where the popliteal fossa block was used, the skin was harvested from the lateral leg. The average duration of anesthesia was 128.9min with a range from 60 to 230min. The procedure was largely painless, with no patient requesting for abandoning the procedure.

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5. Discussion

The use of Prilox^® allows a convenient alternative to local infiltration for skin grafting. It can be easily applied in the ward, by the doctor or nurse on duty. It is essential to form a thick layer of the cream on the desired area. An important precaution is to mark the area with indelible marker before application of cream, as the ink tends to fade out at the time of cleaning. After approximately 2h it is noticed that the desired area appears blanched. A needle prick test is done before proceeding with the procedure. The femoral block anesthetizes the anteromedial thigh and anterior thigh completely, and the LCT, the lateral aspect. The posterior thigh is blocked by the sciatic block. The popliteal fossa block allows graft harvesting from the lateral leg. This latter block is of use, when the thigh is not available for grafting, and a long but not very broad sheet is required. Of course, Prilox^® itself may suffice in such a situation. The advantages of the block are that it is faster in onset of action, and much larger areas can be harvested. It however requires a trained medical professional. Sensitivity testing is also mandatory.

An obvious advantage is the duration of pain relief. The average duration with nerve blocks is over 2h, while with Prilox^® it is less than an hour. This long period allows the patient to be safely shifted to the ward and allows the patient to settle in his surrounding before worrying about pain, which is then tackled with injectables. The use of bupivacaine in nerve blocks allows a much longer period of anesthesia, with periods ranging from 5 to 15h [2], [3]. I have not used bupivacaine frequently, but do plan to do so.

Lets focus on Group 2 patients. Femoral block combined with LCT was used in 14 patients. This allowed us to harvest the graft from the anteromedial and anterolateral thigh. LCT block was used alone in three patients, where the anteromedial area was unavailable. Sciatic block is a difficult block to administer, without a nerve stimulator. It was used in only one patient where anterior surface was unavailable. It is possible to use Prilox^® if smaller area is required. In two patients, we combined Prilox^® with nerve blocks. This allowed us to take a small sheet from the posterior thigh. This is an example of the complimentary use of the two techniques.

The use of eutectic mixture of prilocaine and lignocaine has been used in intravenous line insertion [8], [10], [11]. There are reports of the use in infantile circumcision [9], [10], [12]. However, this agent has not been compared to nerve blocks in skin grafting in recent literature. The emphasis here is the judicious use of either technique in burn patients.

To summarise Prilox^® is indicated in:

(1)Skin grafting in pediatric patients. However, the use in infants needs to established as cases of methemoglobinemia [13] are reported.

(2)Patients apprehensive of needless.

(3)A busy burns unit, where Prilox^® application may be carried out by the nurse.

(4)Patients where limited grafts are required.

(5)Selectively in combination with nerve blocks.

Nerve blocks are indicated in:

•Patients where larger amount of graft is required. They may be used quite easily also in patients where graft requirement is smaller.

Nerve blocks are not used in pediatric patients as chances of vascular injury are high.

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6. Conclusion

Prilox^® and nerve blocks are safe and effective techniques for skin grafting normal burn patients. They can be combined judiciously in selected patients. In pediatric patients, Prilox^® is specially indicated, and nerve blocks are specially indicated where larger amount of graft is required, the procedure can be used in other cases also.

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