Inducible nitric oxide synthase (iNOS) activity promotes ischaemic skin flap survival.

We have examined the role of nitric oxide (NO) in a model of functional angiogenesis in which survival of a skin flap depends entirely on angiogenesis to provide an arterial blood supply to maintain tissue viability. The different effects of nitric oxide synthase (NOS) inhibitors on rat skin flap survival appeared to be explained on the basis of their NOS isoform selectivity. Skin flap survival was decreased by iNOS-selective (inducible NOS) inhibitors, S-methyl-isothiourea, aminoguanidine and aminoethylthiorea; unaffected by the non-selective inhibitor nitro-imino-L-ornithine; and enhanced by the cNOS (constitutive NOS, that is endothelial NOS (eNOS) and neuronal NOS (nNOS)) inhibitor, nitro-L-arginine methyl ester. Skin flap survival was reduced in mice with targeted disruption of the iNOS gene (iNOS knockout mice), and the administration of nitro-L-arginine methyl ester significantly increased flap survival in iNOS knockout mice (P<0.05). iNOS immunoreactivity was identified in mast cells in the angiogenic region. Immunoreactive vascular endothelial growth factor (VEGF) and basic fibroblast growth factor were also localized to mast cells. The combination of interferon-gamma and tumour necrosis factor-alpha induced NO production and increased VEGF levels in mast cells cultured from bone marrow of wild-type, but not iNOS KO mice. The increased tissue survival associated with the capacity for iNOS expression may be related to iNOS-dependent enhancement of VEGF levels and an ensuing angiogenic response. Our results provide both pharmacological and genetic evidence that iNOS activity promotes survival of ischaemic tissue.

First webspace deepening: comparing the four-flap and five-flap Z-plasty. Which gives the most gain?

A two-part investigation was undertaken to determine whether a four- or a five-flap Z-plasty gives the greatest increase in length (deepening) over the same radius of a web. In part A, flaps were designed on a model of a webspace made from a plastic frame and Speedo fabric; four types of flaps, three different central limb lengths, and three trials for each length gave a total of 36 observations. In part B, flaps were designed on the natural axillary webs of the pig; three Yorkshire pigs with one type of flap per axillary web gave a total of 12 observations. In part A, the stereometric elongation (percent deepening) produced by the five-flap Z-plasty was similar to that of a single 60-degree Z-plasty (4-cm central limb; five-flap versus a single Z procedure, 72.5+/-4.3 versus 75.0+/-2.5 percent). The 90-degree four-flap procedure gave a 1.59 times greater deepening than the five-flap procedure (4-cm central limb; 90-degree four flap technique, 114.2+/-1.4 percent). The 120-degree four-flap technique gave 2.0 and 1.26 times greater deepening than the five-flap and 90-degree four-flap procedures, respectively (4-cm central limb; 120-degree four-flap technique, 144.2+/-1.4 percent). In part B, the 90-degree four-flap Z-plasty again produced a significantly greater lengthening (1.57 times) than the five-flap procedure (132.7+/-6.4 versus 84.0+/-4.0 percent; p<0.05), and the percentage of elongation of the 120-degree four-flap procedure was 1.27 times greater than that of the 90-degree four-flap technique (167.3+/-7.0 versus 131.3+/-2.3 percent; p < 0.05). In conclusion, the four-flap Z-plasty produced greater webspace deepening than that of the five-flap Z-plasty. The 120-degree four-flap procedure gave the greatest percentage of elongation, but it was more difficult to design and close than the 90-degree four-flap Z-plasty.

Autotransplantation of epithelial cells in the pig via an aerosol vehicle.

A new method of delivery of epithelial suspensions with use of an aerosolization apparatus was examined in the pig. Full-thickness pig skin was harvested, and an epithelial suspension was created using standard techniques of dispase and trypsin. Twenty-four hours after skin harvest, four full-thickness wounds were created on the flanks of the pig. The control wound was sprayed with a solution without epithelial cells. The three experimental wounds were sprayed with epithelial cell suspensions (integral 10(6) cells/suspension). Weekly evaluation with photographs, biopsies, and tracings were done for 4 weeks. At 10 weeks, the entire process was repeated with new wounds on the pig's back. Thirty-five wounds in five pigs were evaluated: 10 control (5 flank, 5 back) and 25 experimental (15 flank, 10 back). Control wounds healed by contraction alone, with epithelium at the edges only. After 4 weeks, an open area remained. Central epithelial islands developed in experimental wounds at 2 weeks. These islands coalesced to close the wounds by 4 weeks. Histology at 1 week showed groups of epithelial cells deeply embedded in granulation tissue. These groups became immature epithelial layers on the surface by 2 weeks, and all layers of epithelium were present by 4 weeks. Overall, flank experimental wounds epithelialized sooner, but contracted at the same rate as control wounds. In conclusion, epithelial cells can be delivered by an aerosolization apparatus and remain viable and proliferative in a pig model.

Decreasing the perioperative complications associated with the superior pharyngeal flap operation.

This outcome study was a continuation of a previously published review. It examined whether there had been a decrease in the number of acute perioperative complications surrounding superior pharyngeal flap operations since a patient's death in 1990. A total of 386 patients were divided into two groups: the early group (July of 1985 to December of 1990) n = 164, and the later group (January of 1991 to June of 1996) n = 222, which were statistically comparable. The patient complication rate decreased from 19.5 to 6.3 percent (chi square, p = 0.0001). Airway obstruction decreased from 11 to 3.2 percent (chi square, p = 0.0012). Bleeding complications decreased from 7.3 to 1.4 percent (chi square, p = 0.0027). The majority of airway complications (72 percent) and bleeding complications (80 percent) occurred in the first 24 hours. Predictive factors for complications included the surgeon involved, patients with associated medical conditions, having an associated procedure performed concurrently, and leaving the donor site open (multiple logistic regression). Hospital stay also decreased from 5.8 +/- 2.5 to 3.8 +/- 1.6 days (Student's t test p = 0.0001). The decrease in complication rate was due to the increased awareness of all staff involved and also due to changes in surgical management, including a decrease in the number of surgeons (from seven to four surgeons), a decrease in the number of associated procedures (10.4 to 4.5 percent, chi square, p = 0.026), a decrease in the number of open donor sites (34.8 to 4.5 percent, chi square, p = 0), and an increase in the use of nasopharyngeal airways (17.1 to 45 percent, chi square, p = 0). The superior pharyngeal flap operation has become a safer procedure in this hospital.

Assessment of cosmetic and functional results of conservative versus surgical management of facial burns.

This study was undertaken to determine whether tangential excision and thick split-thickness skin grafting (STSG) of deep facial burns give a better cosmetic and functional result than conservative management. Forty patients (28 adults, 12 children) treated for facial burns between July 1989 and July 1991 were evaluated in follow-up (mean 18.3 +/- 8.3 months). The patients were categorized into the following groups according to depth and management of their facial burns: (A) healed without surgery in less than 21 days (n = 13), (B) healed without surgery in 21 days or more (n = 11), (C) early debridement and thick STSG in 18 days or less after the burn (n = 6), and (D) delayed debridement and thick STSG in more than 18 days after the burn (n = 10). Facial esthetics were evaluated by use of a modified scar assessment scale [range 0 (normal) to 16 (multiple abnormalities)], and functional problems of the face and neck were evaluated by use of physical examination. Group A patients had a significantly better overall rating on the scar assessment scale (2.1 +/- 2.9) than the patients in the other groups that required more than 21 days to heal, B (8.0 +/- 2.7), C (7.3 +/- 2.9), and D (5.7 +/- 2.5) (p < 0.01, analysis of variance). Also, skin-grafted areas in the surgically treated groups C and D had a significantly better scar rating than wounds that healed spontaneously in group B (5.7 +/- 4.0 vs 8.0 +/- 2.7, p < 0.05; and 5.1 +/- 2.6 vs 8.0 +/- 2.7, p < 0.05). There was no significant difference among groups B, C, and D when the total number of persistent functional problems after treatment were compared. The most common functional problems for these patients were microstomia (17/27) and eyelid ectropion (17/27). Patients with superficial facial burns that heal in less than 21 days appear to heal with generally very acceptable cosmetic and functional results. However, in those patients with deep facial burns that require prolonged periods for spontaneous wound healing, tangential excision of the wound and resurfacing with thick STSG appear to give better cosmetic results than conservative management, with no greater incidence of functional complications.

Functional evaluation of the shoulder following latissimus dorsi muscle transfer.

The dynamic muscle function of the shoulder in 26 patients (10 males, 16 females) who underwent a pedicled or free vascularized latissimus dorsi muscle transfer between 1985 and 1991 (mean follow-up, 4.4 yr) was studied. Instrumented muscle testing was performed on the Kinetic Communicator machine (Kin Com) and the Baltimore Therapeutic Equipment (BTE) work simulator. The female unilateral pedicle group (n = 13) showed a significant difference between operated and nonoperated shoulders for both peak torque (power) and work (endurance) measurements of shoulder adduction and extension on the Kin Com (mean ratios operated/nonoperated shoulders, 55% to 69%). They also showed significant differences for work performance on three of four BTE tests (mean ratios, 77% to 84%). The male free vascularized group (n = 10) similarly showed a significant deficit of both peak torque and work for shoulder extension and adduction on the Kin Com (mean ratios, 74% to 84%); however, they showed no deficit on the BTE tests. In conclusion, dynamic muscle tests demonstrate a deficit of muscle power and endurance of shoulder extension and adduction following latissimus dorsi muscle transfer.

Subcutaneous instillation of donor sites in burn patients.

A simple technique of powered subcutaneous instillation of split-thickness skin graft donor sites in burn patients and other plastic surgical patients has been developed. The necessary equipment required, including a standard pneumatic tourniquet, arterial pressure bags and spinal needles, is available in any plastic surgery operating theatre. In over 300 cases in which it has been employed, no complications have been encountered.

Value of cultures of tissue samples taken at operation for lower intestinal perforation.

Tissue cultures from perforations of the lower intestinal tract commonly yield both aerobes (coliform organisms) and anaerobes (Bacteroides sp. and Clostridium sp.). To determine the consistency of this pattern and the value of intraoperative cultures, the authors reviewed the hospital records of 115 patients with perforation of the appendix (100 patients) or colon (15 patients), treated between 1987 and 1990, in whom organisms were cultured from tissue samples taken intraoperatively. Attention was paid to the organisms cultured, their distribution and antibiotic sensitivity in initial samples and in subsequent samples obtained when there were septic complications. On average, 4.7 bacterial isolates per patient were obtained. The common organisms were as expected: Bacteroides fragilis, Escherichia coli and Clostridium sp. Although the culture results did not affect the management of these patients, the sensitivity of Bacteroides fragilis to cefoxitin was found to be lower than expected, indicating a shift in sensitivity.