A study of regional nerve blocks and local anesthetic creams (Prilox®) for donor sites in burn patients
Article Outline
- Abstract
- 1. Background
- 2. Anatomy of nerve blocks
- 3. Materials and methods
- 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
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 5
h, 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.
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].
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
3.2. Exclusion criteria
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 | 2 | 45 | Nil |
| 2 | 13 | 10 | 10 | 4 | 60 | Nil |
| 3 | 6 | 10 | 10 | 3 | 30 | Nil |
| 4 | 65 | 25 | 25 | 0 | 60 | Nil |
| 5 | 47 | 25 | 25 | 2 | 80 | Nil |
| 6 | 31 | 15 | 10 | 1 | 40 | Nil |
| 7 | 28 | 25 | 20 | 2 | 45 | Nil |
| 8 | 7 | 10 | 5 | 4 | 50 | Nil |
| 9 | 52 | 25 | 5 | 6 | 60 | Nil |
| 10 | 10 | 10 | 3 | 3 | 30 | Nil |
| 11 | 45 | 20 | 12 | 0 | 45 | Nil |
| 12 | 32 | 25 | 20 | 1 | 70 | Nil |
| 13 | 33 | 25 | 20 | 0 | 50 | Nil |
| 14 | 26 | 20 | 15 | 0 | 40 | Nil |
| 15 | 29 | 20 | 15 | 0 | 60 | Nil |
| 16 | 40 | 25 | 25 | 3 | 35 | Nil |
| 17 | 56 | 25 | 20 | 2 | 45 | Nil |
| 18 | 70 | 25 | 10 | 7 | 60 | Nil |
| 19 | 38 | 25 | 20 | 2 | 65 | Nil |
| 20 | 21 | 20 | 15 | 4 | 90 | Nil |
| 21 | 18 | 20 | 15 | 1 | 45 | Nil |
| 22 | 19 | 25 | 25 | 0 | 50 | Nil |
| 23 | 45 | 20 | 15 | 1 | 50 | Nil |
| 24 | 42 | 25 | 20 | 1 | 60 | Nil |
| 25 | 49 | 25 | 20 | 1 | 45 | Nil |
| 26 | 31 | 25 | 20 | 1 | 55 | Nil |
| 27 | 64 | 20 | 15 | 1 | 35 | Nil |
| 28 | 28 | 25 | 20 | 2 | 60 | Nil |
| 29 | 30 | 25 | 20 | 2 | 45 | Nil |
| 30 | 12 | 15 | 10 | 2 | 60 | Nil |
| 31 | 34 | 25 | 25 | 3 | 65 | Nil |
| 32 | 26 | 20 | 20 | 1 | 20 | Nil |
| 33 | 28 | 15 | 10 | 0 | 45 | Nil |
| 34 | 47 | 25 | 20 | 2 | 60 | Nil |
| 35 | 41 | 20 | 15 | 1 | 50 | Nil |
| 36 | 40 | 25 | 20 | 0 | 40 | Nil |
| 37 | 30 | 25 | 20 | 2 | 30 | Nil |
| 38 | 37 | 20 | 15 | 1 | 80 | Nil |
| 39 | 24 | 25 | 20 | 3 | 55 | Nil |
| 40 | 71 | 25 | 25 | 2 | 75 | Nil |
| 41 | 43 | 25 | 20 | 2 | 40 | Nil |
| 42 | 56 | 20 | 15 | 1 | 65 | Nil |
| 43 | 39 | 25 | 20 | 1 | 40 | Nil |
| 44 | 51 | 25 | 20 | 0 | 50 | Nil |
| 45 | 22 | 25 | 20 | 0 | 60 | Nil |
| 46 | 27 | 20 | 15 | 3 | 45 | Nil |
| 47 | 52 | 25 | 20 | 2 | 50 | Nil |
| 48 | 9 | 15 | 10 | 1 | 45 | Nil |
| 49 | 35 | 15 | 10 | 1 | 50 | Nil |
| 50 | 40 | 20 | 15 | 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 | 0 | 160 | Nil |
| 2 | 39 | F, LCT | 20 | 2 | 200 | Nil |
| 3 | 47 | F | 25 | 1 | 180 | Nil |
| 4 | 65 | F | 25 | 0 | 200 | Nil |
| 5 | 73 | F | 25 | 0 | 100 | Nil |
| 6 | 25 | F | 15 | 0 | 230 | Nil |
| 7 | 45 | F | 10 | 0 | 110 | Nil |
| 8 | 65 | F | 5 | 4 | 190 | Nil |
| 9 | 23 | F/LCT | 20 | 2 | 110 | Nil |
| 10 | 26 | LCT | 20 | 3 | 90 | Nil |
| 11 | 40 | LCT | 10 | 1 | 125 | Nil |
| 12 | 21 | F, LCT | 25 | 1 | 130 | Nil |
| 13 | 32 | S | 15 | 1 | 100 | Nil |
| 14 | 37 | F | 10 | 1 | 60 | Nil |
| 15 | 34 | LCT | 10 | 5 | 160 | Nil |
| 16 | 29 | PF | 12 | 0 | 100 | Nil |
| 17 | 18 | F, LCT | 15 | 2 | 90 | Nil |
| 18 | 32 | F | 10 | 2 | 150 | Nil |
| 19 | 26 | F | 15 | 2 | 160 | Nil |
| 20 | 49 | F | 15 | 2 | 135 | Nil |
| 21 | 63 | F, LCT | 10 | 3 | 160 | Nil |
| 22 | 50 | F, LCT, +pri (15 grams) | 20 | 1 | 125 | Nil |
| 23 | 60 | F | 5 | 1 | 110 | Nil |
| 24 | 24 | F | 10 | 1 | 90 | Nil |
| 25 | 51 | F/LCT | 10 | 1 | 95 | Nil |
| 26 | 18 | PF | 10 | 1 | 100 | Nil |
| 27 | 20 | F | 10 | 0 | 185 | Nil |
| 28 | 21 | F | 20 | 0 | 145 | Nil |
| 29 | 43 | F | 15 | 0 | 160 | Nil |
| 30 | 34 | F | 25 | 0 | 125 | Nil |
| 31 | 35 | F | 25 | 0 | 100 | Nil |
| 32 | 38 | F | 25 | 2 | 90 | Nil |
| 33 | 30 | F, +pri (15 grams) | 8 | 4 | 120 | Nil |
| 34 | 20 | F/LCT | 25 | 3 | 120 | Nil |
| 35 | 21 | F | 25 | 2 | 130 | Nil |
| 36 | 54 | F, LCT | 25 | 3 | 120 | Nil |
| 37 | 65 | F | 15 | 3 | 110 | Nil |
| 38 | 24 | F | 8 | 2 | 100 | Nil |
| 39 | 48 | F | 5 | 1 | 95 | Nil |
| 40 | 49 | F, LCT | 10 | 0 | 150 | Nil |
| 41 | 36 | F, LCT | 15 | 1 | 140 | Nil |
| 42 | 38 | F | 20 | 1 | 135 | Nil |
| 43 | 35 | F | 15 | 1 | 150 | Nil |
| 44 | 41 | F | 10 | 2 | 100 | Nil |
| 45 | 21 | F, LCT | 10 | 2 | 120 | Nil |
| 46 | 23 | F, LCT | 25 | 2 | 145 | Nil |
| 47 | 27 | F | 25 | 0 | 185 | Nil |
| 48 | 29 | F, +pri | 15 | 2 | 100 | Nil |
| 49 | 32 | F | 25 | 0 | 60 | Nil |
| 50 | 33 | F/LCT | 25 | 1 | 100 | Nil |
4. Results
In Group 1, the average post operative analgesia is 51.8
min with a range of 30–90
min. 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 128.9
min with a range from 60 to 230
min. The procedure was largely painless, with no patient requesting for abandoning the procedure.
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 2
h 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 2
h, 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 15
h [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:
Nerve blocks are indicated in:
Nerve blocks are not used in pediatric patients as chances of vascular injury are high.
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.
References
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PII: S0305-4179(06)00149-5
doi:10.1016/j.burns.2006.04.019
© 2006 Elsevier Ltd and ISBI. All rights reserved.
