Antimicrobial Effects of Lidocaine, Bicarbonate, and Epinephrine
Background.—Local anesthetic agents have antibacterial properties. The antimicrobial effects of lidocaine, bicarbonate, and epinephrine on pathogens commonly seen in immunocompromised patients were examined.
Methods.—The culture study considered 2 bacteria—Staphylococcus aureus and Pseudomonas aeruginosa—and 7 fungi—Sporothrix schenckii. Cryptococcus neoformans, Aspergillus flavus, Histoplasma capsulatum, Blastomyces dermatitidis, Candida albicans, and Fusarium spp. The anti-microbial effects of lidocaine were tested using concentrations of 1%, 0. 5%, and 0.1%; bicarbonate was tested in concentrations of 100,25, and 12.5 mEq/mL; and epinephrine was tested in dilutions of 1:100,000, 1:200,000, and 1:1,000,000.
Results.—For lidocaine and epinephrine, the time-kill curves for both bacterial pathogens were not significantly different from controls. How-ever, bicarbonate tended to inhibit the growth of both bacteria with increasing time and concentration.
Lidocaine significantly inhibited the growth of Fusarium and Aspergillus at 1 hour. One-hour growth inhibition of B. dermatitidis was also seen; growth decreased over 12-24 hours. Similar kill rates were noted for S. schenckii, H. capsulatum, and C. albicans; inhibition with increasing concentration was apparent by 1 hour, and with concentration and time by 2 hours. Growth of C. neoformans decreased three-fold within 1 hour, and was negligible at later times.
With epinephrine, the growth of Fusarium, Aspergillus, and C. neoformans was minimal after 1 hour, which suggested inhibition with increasing concentration and time. A similar pattern was noted for C. albicans. Growth of H. capsulatum and S. schenckii was reduced two- to four-fold at 1 hour, and there was continued inhibition over time. Epinephrine inhibited the growth of B. dermatitidis at all concentrations and times.
Bicarbonate significantly inhibited the growth of H. capsulatum, C. albicans, C. neoformans, S. schenckii, and B. dermatitidis with increasing concentrations and times. Both Fusarium and Aspergillus showed little or no growth at any concentration of bicarbonate.
Conclusions.—Lidocaine, epinephrine, and bicarbonate have significant antimicrobial effects, particularly against common fungi. This may help to explain the low infection rate after cutaneous surgery. The antimicrobial effects of local anesthetics should be taken into account when diagnostic methods are considered.
► The implications of this study are quite clear. When obtaining biopsy specimens for culture, epinephrine and bicarbonate should be avoided. Lidocaine should be used in a ring block at the lowest possible concentration.
Prilocaine/Lidocaine Patch as a Local Premedication for Skin Biopsy in Children
Introduction.—Several studies have reported success with the use of topical prilocaine-lidocaine cream (EMLA) as a local anesthetic in patients undergoing skin biopsy procedures. Such procedures usually require the infiltration of a local anesthetic, which itself is often painful. Children requiring a skin biopsy took part in a study designed to determine the analgesic effect of a patch formulation of EMLA.
Methods.—The randomized, double-blinded study used 2 parallel groups: 31 children received an EMLA patch and 32 received a placebo patch for 60 minutes at the site of biopsy. The patch was then removed, the skin infiltrated with 1 mL of lidocaine, and a biopsy was performed with a 4 mm punch. Children indicated their level of pain on a visual analog scale. Both the child and physician reported level of pain on a verbal scale from “no pain” to “severe pain.” Pain was scored after injection of lidocaine and after the punch biopsy.
Results.—Sixty children could be evaluated. The mean age was 9.6 years in the EMLA group and 8.5 years in the placebo group. On the visual analog scale, the EMLA patch was significantly more effective than the placebo patch in decreasing pain at the injection site. Pain scores of the biopsy procedure did not differ significantly between the 2 groups. Similarly, the verbal pain scores for the injection were significantly lower in the EMLA group, whereas the verbal pain scores for the biopsy were similar in EMLA and placebo groups.
Conclusion.—Children who received an anesthetic patch had significantly reduced pain at the site of lidocaine infiltration before a skin biopsy procedure. Because the lidocaine provides adequate anesthesia, pain scores for the biopsy were similar in the anesthetic patch and placebo patch groups. Girls appeared to experience more pain than boys.
► This article attempts to apply objective measures and statistical analysis to prove that EMLA works in children. Those of us who use the EMLA patch in our daily pediatric dermatology practices know that it works in many cases. However, in some children, fear and not pain is the major behavioral determinant. The physician must take time with these children prior to the injection to gain their trust and allay their fear. The use of EMLA cream does not remove this responsibility and time commitment from the physician.
Remember that the EMLA patch must be applied for 2-3 hours prior to the procedure for full effect and that an adequate amount of cream must be used. And remember too that EMLA works for superficial pain, such as injections and blood drawing, but not for deeper pain such as full-thickness skin biopsies and excisions. These still will require infiltration anesthesia.
One interesting finding in this study was that girls reported higher pain scores on the visual analog scale and on verbal scales. Boys are perhaps conditioned to “tough it out” and not admit fear or pain. Whether this makes painful procedures more or less stressful for boys is not known.
Electrosurgery and Cardiac Devices
Objective.—Electrosurgery has become an important technique for office-based treatment. For physicians performing electrosurgical procedures, the growing number of patients with implantable cardiac devices (i.e., pacemakers, implantable cardiac defibrillators [ICDs]) poses a special challenge. Key issues related to the use of electrosurgery in patients with implantable cardiac devices are reviewed.
Electrosurgery.—Technically, electrocautery is not a form of electrosurgery. Because no electric current passes to the patient, the associated risk to cardiac devices is minimal. High-frequency electrosurgery involves the passage of high-frequency alternating current to and through the tissues, and can include electrofulguration, electrodessication, electrocoagulation, and electrotomy (“cutting current”). Both electrocoagulation and electro- tomy involve large amounts of current flow, and a dispersive plate must be used as an indifferent electrode or ground. Whether the active and dispersive electrodes are widely separated or close together, there are two points of contact between the electrosurgical device and the patient. The patient is always in the electrical circuit.
Complications.—The electromagnetic forces produced by electrosurgery can disrupt the functioning of an ICD. Such interference can lead to profound bradycardia or asystole, pacemaker reprogramming, pulse generator inhibition or damage, and direct myocardial stimulation causing arrhythmias or injury. These complications involve only high-frequency electrosurgery, mainly electrotomy. There have been no reports of such complications resulting from cutaneous electrosurgery. Several important design changes have been made in implantable cardiac devices to prevent electromagnetic interference. However, when any type of high-frequency electrosurgery is performed in a patient with a pacemaker or ICD, appropriate precautions should be taken.
In patients with pacemakers, inhibition by interference can occur if the pacemaker detects current produced by electrosurgery, leading to asystole or bradycardia. If the pacemaker reads the signals from the electrosurgery unit as commands, the device may be reprogrammed. This is called true interference. In patients with ICDs, oversensing can occur if the device reads the interference as an arrhythmia and responds by delivering a shock. The result can be ventricular tachycardia, fibrillation, or myocardial burns. Undersensing refers to inadvertent deactivation of the defibrillator, leaving the patient vulnerable to an arrhythmia. The risk of these complications is greatest with electrocoagulation and electrotomy.
Risk Assessment and Monitoring.—If electrosurgery is planned in a patient with an ICD, the patient’s cardiologist should be consulted beforehand. For patients who are critically dependent on the pacemaker, continuous ECG monitoring should be used. When-the electrosurgical unit is activated, ECG monitoring will be invalid; thus the patient’s pulse should be monitored. Electrodessiccation or electrofulguration should be used whenever possible. If electrocoagulation or electrotomy must be performed, a forceps device may be used to limit dispersal of current beyond the surgical site; or the dispersive plate should be placed as far away as possible from the cardiac device and heart. Limiting electrosurgical activation to 5- to 10-second bursts will prevent prolonged distortion and inadvertent reprogramming or deactivation. If interference is noted during electrosurgery, placing a magnet over the pulse generator of a pacemaker will convert it to a fixed-rate, nonsensing mode. This will prevent inhibition of pacemaker function.
► More and more dermatologic surgery patients have either a cardiac pacemaker or an implantable defibrillator. Although these devices are much less susceptible to outside interference than their predecessors, certain precautions need to be taken if an electrosurgical device is going to be employed. This article nicely reviews the major types of ICDs and the most frequently used electrosurgical modalities. The authors discuss the potential complications of electrosurgery in these patients and how to avoid them. This article is a must for all clinicians using electrosurgical equipment.
The Sentinel Vein: An Important Reference Point for Surgery in the Temporal Region
Background.—Surgeons who perform reconstructive or aesthetic surgery of the brow and midface must have an intimate knowledge of the anatomy of the face. Such knowledge helps to improve results and minimize complications. The major complication associated with brow lifts is trauma to the temporal branch of the facial nerve. Although the general course of this nerve is well documented, exact details are unknown. An anatomical study was conducted to clarify the path of this nerve.
Methods.—The anatomical relationship of the sentinel vein and temporal branch of the facial nerve were documented from dissections performed on each side of 10 fresh cadaver heads (20 sides total). The average age of the specimens was 76.5 years.
Findings.—A consistent relationship was seen between the temporal branch of the facial nerve and the sentinel vein. The temporal branch of the facial nerve consistently crossed the zygomatic arch between points that were 19-27 mm anterior to the base of the zygomatic arch. The sentinel vein was present in every dissection and consistently lay lateral to the lateral orbital rim. It passed from the subcutaneous layer through the temporoparietal fascia and through a perforation in the deep temporal fascia to the temporalis muscle. It had a consistent location relative to fixed skeletal landmarks.
Discussion.—Preoperative identification of the sentinel vein and marking the “zone of caution” enables the surgeon to operate rapidly and confidently until the upper border of the zone of caution is reached. At this point, dissection is slower as the vein is approached under endoscopic control. If the sentinel vein is not apparent externally, it may be identified through fixed skeletal landmarks. Detailed findings from the dissections are also included.
► The temporal branch of the facial nerve is a “danger zone” during facial surgery. The authors here present an interesting cadaveric study to identify the path of the temporal sentinel vein and its close relationship to the temporal branch of the facial nerve. During endoscopic brow lifts or other surgery in the temporal region, this vein may serve as an anatomical land-mark to define an area of caution; surgeons should avoid injury to this branch of the facial nerve to avoid subsequent neurologic deficit.
The Temporary Alar Suspension Stitch: A Refinement in Forehead Flap Reconstruction of Nasal Defects
Background.—The paramedian forehead flap is commonly used for repair of nasal defects of the tip and supratip. There have been various refinements to the forehead flap procedure for nasal reconstruction. The author has begun to use a temporary stitch to avoid transfer of thick, hair-bearing scalp skin to the nose in padents with defects of the nasal tip or supratip and low frontal hairlines. In the author’s opinion, the texture of hair-bearing scalp skin blends less well with the recipient nasal skin than the skin of the forehead.
Case Report.—Woman, 53, was referred for reconstruction of a full-thickness Mohs’ defect of the nasal tip and supratip after excision of a skin cancer. The nasal cartilages were not involved in the excision. The infratip lobule extension of the flap extended into the hair-bearing scalp after determination of pedicle length. After excision of the cephalic margins of the underlying lower lateral cartilages was performed, the cartilages were permanently approximated as a double dome unit using a 5.0 polydiaxone suture to narrow, define, and rotate the tip and improve esthetics. A temporary alar suspension stitch was placed, which allowed flap placement well below the hairline.
Discussion.—This technique has only been used in cases of skin reconstruction of the tip and supratip with intact lower lateral nasal cartilages, but it may also be useful when minimal reconstruction of the nasal tip cartilages is needed. Details of the suture technique and the rationale were also discussed.
► The author describes a temporary suspension stitch for use during forehead flap reconstruction. The stitch runs from the medial and lateral crura of the lower lateral cartilages to the glabella. This is an attempt to provide adequate nasal coverage in patients with low foreheads or low anterior hairlines. Despite the acceptable results presented here, this suture technique carries significant risks: The stitch placed in the glabella may jeopardize the vascular integrity of the flap, and the stitch placed through the lower lateral nasal cartilages, should it fail, produces significant risk of vascular compromise. Curvilinear forehead flaps or more aggressive thinning of hair- bearing distal flaps may prove a safer technique for the management of-large nasal defects.
Interferon Alpha-2A Therapy for Keloids
Introduction.—A keloid represents abnormal scarring that persists for more than a year after injury. Many different treatments have been proposed, but keloids continue to be a difficult problem for patients and physicians alike. Recombinant human interferon has been shown to down- regulate collagen synthesis; in keloid patients interferon treatment may switch off excess collagen formation. The successful use of alpha-2 interferon to treat extensive keloids was reported.
Case.—Boy, 13, was treated for extensive keloid formation on the right face, both arms, and right upper trunk. The keloids developed after a bum sustained 8 months previously, and had grown to a height of 0.5-1.4 cm. The patient was treated with alpha-2 interferon in an IM loading dose of 0.6 MU/cm2 of the lesion 3 times weekly for 2 weeks. This was followed by a dose of 1 MU/cm2 of the lesion once weekly for 6 weeks.
Weekly laboratory follow-up showed slightly elevated IgE levels. The patient underwent 3 surgical procedures during treatment, with no new keloid formation. No surgery was performed directly on the keloids. Lesions of the anterior and posterior chest were flattened, softer; and paler. Improvement in the arm lesions led to improved function. At 18 months’ follow-up, there were no recurrences.
Discussion.—This patient’s extensive keloids responded to treatment with interferon alpha-2a. Interferon provided a useful approach to management in a difficult situation in which other treatments were not feasible. The mechanism of interferon’s effects on keloidal tissue is unknown.
► Berman and Flores have recently shown that postoperative triamcinolone injections of keloids do not reduce the number of recurrences ; however, injection of keloid excision sites with interferon alpha-2b is associated with a significant decrease in recurrence rates.
Recurrence Rates of Excised Keloids Treated With Postoperative Triamcinolone Acetonide Injections or Interferon Alfa-2b Injections
Objective.—The rate of recurrence of keloids after surgical excision ranges from 45% to 100%. Techniques such as postexcisional injections of corticosteroids or interferon (IFN), silicone sheeting, radiotherapy, and pressure splints or garments have been used to reduce recurrence rates. A retrospective comparison of the recurrence rates of keloids treated by excision alone or excision followed by injection of IFN-a2b or triamcinolone acetonide (TAC) is presented.
Methods.—Between January 1993 and August 1996, 124 (103 previously treated) keloids, 0.5-15 cm, were excised from 74 patients (8 males, 9 whites), age 8-61. Causes of keloids were ear piercing (50%), chicken pox (3%), surgery (5%), burn (1.4%), trauma (9%), and unknown. Fifteen patients had a recurrence. After excision, 65 sites were injected with TAC into the suture line (10-40 mg/mL per treatment for 1-4 treatments), 16 were injected with IFN-α2b (1 million U in 0.1 mL/linear cm per treatment), and 43 sites received no postexcision treatment. Twelve of the IFN-treated sites were reinjected 1 week later with 5 million U.
Results.—If all keloids lost to follow-up are assumed to have recurred, the recurrence rate for TAC-treated keloids was 58.5%, for IFN-α2b- treated keloids was 18.7%, and for keloids treated surgically only was 51.2%. There was a significant difference between IFN-α2b-treated keloids and untreated keloids, but not between the keloids treated with intralesional TAC and those left untreated.
Conclusion.—Whereas postsurgical injections of TAC do not significantly reduce recurrence of keloids, injections of IFN-α2b do.
► Although this study is small, the authors were able to achieve a significant decrease in keloid recurrent rates after postoperative interferon alfa-2b injections. Comparisons of placebo and intralesional triamcinolone injected postoperatively showed no statistically significant difference. The dose of interferon used was quite small and was well tolerated by the patients. Interferon alfa-2b injections may represent a useful addition to existing treatments for keloids. A larger prospective trial is warranted.
The Influence of Dressings on Venous Ulcer Healing: A Randomised Trial
Purpose.—The authors’ standard dressing for leg ulcers is a paste bandage (Viscopaste) with minimal stretch bandages (Elastrocrepe). However, paste bandages are expensive and take a long time to apply. Three different dressings under stretch bandages were compared in terms of healing time and ease of application, and factors influencing time to healing were examined.
Methods.—The 3 dressings were a zinc oxide-impregnated paste bandage (Viscopaste), a zinc oxide-impregnated stockinette (Acoband), and a calcium alginate fiber dressing (Kaltostat). The zinc oxide stockinette was chosen for comparison with the paste bandage, and the calcium alginate fiber dressing for its possible direct effects on wound healing. The ulcers studied ranged in diameter from 0.5 to 10.0 cm; all patients were treated in a specialized leg ulcer clinic. Treatment continued for 9 months or until ulcer healing; any other reason for discontinuation was considered a treatment withdrawal. For each patient, ulcer healing was calculated as rate of size reduction per week in square centimeters.
Results.—A total of 133 ulcerated limbs in 113 patients were examined. All ulcers were caused exclusively by venous disease. The 3 groups were comparable in terms of ulcer size, ulcer duration, and other parameters. Acceptability was greatest for Viscopaste, with treatment continuing until ulcer healing or 9 months in 86% of patients. For Acoband and Kaltostat, the rates were 66% and 59%, respectively. Healing time was greatly affected by dressing type, being best with Viscopaste. Ulcer size and side of the ulcerated limb (right side being more likely to heal) were also significantly associated with healing. Other factors including ulcer duration, number of ulcer episodes, and deep venous status were nonsignificant.
Conclusions.—In patients with leg ulcers, the use of a zinc oxide impregnated bandage under compression bandage produces better healing rates than zinc oxide-impregnated stockinette or local alginate fiber dressing. Total limb healing, as used in this study, is the only effective parameter for evaluating clinical treatments for venous ulcer. In addition to the use of a paste bandage, ulcer size and right leg ulcer have a significant effect on ulcer healing time.
Efficacy of Pinch Grafting in Leg Ulcers of Different Aetiologies
Background.—Pinch grafting is an ulcer treatment technique in which small pieces.of epidermis are harvested for transplantation by shaving off the top of a fold of skin pinched between the thumb and forefinger. The authors have been using this technique since 1990. Their results with 145 pinch graft transplantations were reported.
Methods.—Pinch grafting was used to treat 145 leg ulcers during a 3- year period. All ulcers had failed to respond to conservative therapy, were large ulcers with an expected prolonged healing time, or painful ulcers. The healing rate after 3 months was retrospectively determined.
Results.—The 3-month healing rate was 36%. Healing rate was 50% for arteriosclerotic ulcers, 42% for combined venous and arteriosclerotic ulcers, and 22% for pure venous ulcers. A healing rate of 83% was achieved for hydrostatic ulcers—those located between the knee and ankle with no evidence of arterial or venous insufficiency or small vessel disease.
Conclusions.—A 40% healing rate was reported with pinch grafting of treatment-resistant leg ulcers. This useful technique is simple to execute and requires no special equipment. Pinch grafting should be the first option for transplantation therapy of leg ulcers. Second-line treatment, if needed, should consist of ulcer excision and split-thickness skin grafting.
► With the methods of these authors mentioned (Abstracts 22-8 and 22-9), it should be noted that another helpful suggestion has been made by Layton et al., who showed that the addition of 1 aspirin per day to a regimen of excellent local care could significantly increase the rate of healing of venous leg ulcers.
Pinch Grafting of Leg Ulcers: A Retrospective Study of 412 Treated Ulcers in 146 Patients
Objective.—Outcome after treatment of leg ulcers using the modified pinch graft method was studied retrospectively to determine healing rates and remission times.
Methods.—Between 1990 and 1996, 149 patients (37 men) with 415 venous (n = 207), arteriosclerotic (« = 39), vasculitic (n – 43), mixed (n = 108), and other (n = 18) leg ulcers were treated with pinch grafting that made use of an average of forty-six 3- to 5-mm pieces of full-thickness skin. The anterolateral aspect of the thigh was the donor site. Skin sections were placed over the ulcer 2-5 mm apart, and the wound was covered with petrolatum gauze, an occlusive dressing, and a. pressure bandage. Saline compresses were changed as secretions required. After a week in bed, the petrolatum gauze was removed and replaced with an ointment-impregnated stockinette. Healing times were as long as 6 months. Patients were followed for an average of 32 months.
Results.—The average healing time was 9.4 weeks. Healing rates were 22% at 2 months and 38% at 6 months. Specific healing rates were 38% for venous ulcers, 33% for arteriosclerotic ulcers, 56% for vasculitic ulcers, 33% for mixed ulcers, and 20% for other ulcers. At 6 months 133 ulcers were improved, making the healed/improved rate 70%. Healing rate in small and medium-sized ulcers was 43% and in large ulcers was 20%. The average hospital stay was 30 days. The recurrence rate for venous ulcers was 27% after an average of 13.8 months, for arteriosclerotic ulcers it was 38% after an average of 5 months, for vasculitic ulcers it was 25% after an average of 15 months, and for mixed ulcers it was 28% after an average of 15 months. One of the 3 other ulcers recurred at 12.5 months. The remission time for 112 ulcers healed at the end of the study was 26.6 months. Ulcers that healed after 2 months were less likely to relapse than ulcers that healed within 2 months.
Conclusion.—The overall healing rate for leg ulcers treated by the pinch graft method was 38%. The recurrence rate was 28%.
► Leg ulcers can be notoriously resistant to conservative management. In this article, the authors reviewed their experience with pinch grafting in the management of 415 leg ulcers in 149 patients. Small and medium size ulcers of short duration healed best (43% healing rate). Of the healed ulcers, 28% recurred. The mean hospital stay was 30 days (range, 8-90 days). No comment was made regarding the healing time of the donor sites or the cosmetic appearance of the recipient or donor sites, three outcome measures that need to be addressed. Also not addressed was a comparison of the costs (including those associated with hospitalization) and results achieved with pinch grafting as compared with split thickness skin grafting and autologous cell culture grafting. Finally, it is unclear why prolonged hospitalization was necessary.
Hypoxia Increases Human Keratinocyte Motility on Connective Tissue
Objective.—Healing of skin wounds depends on the migration of kera- tinocytes from the wound margins, resulting in reepithelialization. This migration process is enhanced in a hypoxic environment. Keratinocyte motility was measured in response to extracellular matrix and growth factors to examine the effect of hypoxia on human keratinocyte migration over connective tissue components.
Methods.—Human keratinocytes were cultured in a low (0.2% or 2%) and normal (9% or 20%) oxygen environment. Keratinocyte migration was assessed under both conditions. Relative expression of the lamellipo- diaassociated proteins—ezrin, radixin, and moesin—were determined by means of Western immunoblot analysis. Levels of laminin-5, a keratino- cyte motility inhibitor, were determined using immunofluorescence. The profile of cell-surface integrins was determined by means of fluorescent- activated cell sorting (FACS) analysis. Expression of 92-kD type IV collagenase was analyzed with zymography and immunoblotting, and band intensity was measured with densitometry.
Results.—Keratinocyte migration increased 1.5-2.0 times, and expression of the lamellipodia-associated proteins’was enhanced in a hypoxic environment compared with normoxic conditions. Production of laminin-5 was decreased under hypoxic but not normoxic conditions. Under hypoxic conditions, mean track length of motile keratinocytes increased by approximately 40%, compared with identical cells migrating under normoxic conditions. The profile of cell-surface integrins was unchanged. Hypoxia did not affect protein synthesis but did induce increased expres-sion of 92-kD type IV collagenase.
Conclusion.—Under hypoxic conditions, keratinocyte migration may be initiated by promoting lamellipodia formation, enhancing collagenase expression, or inhibiting production of laminin-5.
► This study challenges the conventional wisdom that provision of significant oxygen is necessary for proper healing of skin wounds. Certainly tissue ischemia correlates with poor healing, and expensive hyperbaric oxygen chambers have been used in the treatment of nonhealing wounds. Conversely, venous ulcers may heal even under conditions of markedly reduced transcutaneous oxygen pressure,1 and semiocclusive dressings promote reepithelialization despite a low pH and almost negligible oxygen tension.2 As suggested by the authors, the many distinct components of wound healing, including coagulation, reepithelialization, angiogenesis, fibroplasia, contraction, and remodeling, may have distinct responses to microenvironmental factors such as hypoxia.