Biomedical subjects
L O Vasconez
Publications and source records attributed to L O Vasconez.
Muscle flap coverage for the lower extremity.
The use of local transposition muscle flaps for coverage of the lower extremity has been overshadowed in recent years by the development of microsurgical techniques for tissue transfer. There are still definite indications for local muscle flaps in reconstruction of the lower extremity. An outline of criteria of selectivity as it applies to specific wounds and practical pitfalls of their use is presented.
Fasciocutaneous flaps in reconstruction of the lower extremity.
The fasciocutaneous flap, when correctly chosen, can supply an expedient solution for some of the challenging soft-tissue problems in the leg. The fasciocutaneous flap should be included in the list of reconstructive options for the lower extremity, particularly in the distal tibia. The improved knowledge of blood supply to the fasciocutaneous flaps allows the design of a safer, longer, more useful flap.
Experimental and clinical applications of fibrin glue.
A 2-year experience with laboratory and clinical applications of fibrin glue is presented. An autologous technique, which eliminates the danger of multidonor preparations, has been developed in our blood bank. While one can obtain different fibrinogen concentrations from the same amount of a patient's blood, in vitro mechanical testing demonstrated that at higher fibrinogen concentrations there is an increase in shear adhesive strength. Evaluation of skin-graft take in 16 Sprague-Dawley rats did not demonstrate significant differences in healing when adhesive use was compared with suture technique. In a clinical study, four different groups of patients (facial burns, hand burns, difficult graft sites, and miscellaneous surgical applications) benefited from autologous or single-donor fibrin glue for a total of 82 cases. There are several distinct advantages to the use of fibrin adhesive: The autologous technique eliminates the risk of transmissible viral diseases (AIDS, hepatitis); it can be used as a sealant in the treatment of seromas, dural leaks, and lymphoceles; and it improves hemostasis and early graft adherence. Face and hands are resurfaced with sheet grafts in a single procedure, obtaining a better aesthetic result with complete graft take and immediate start of physical therapy. Neither sutures nor pressure dressings are required. The minimal postoperative care associated with early return to normal activities seems to increase the satisfaction of patients and nurse personnel.
Use of the omentum in chest-wall reconstruction.
Increased use of the omentum in chest-wall reconstruction has paralleled the refinement of anatomic knowledge and the development of safe mobilization techniques. Important anatomic points are the omental attachments to surrounding structures, the major blood supply from the left and right gastroepiploic vessels, and the collateral circulation via the gastroepiploic arch and Barkow's marginal artery. Mobilization of the omentum to the thorax involves division of its attachments to the transverse colon and separation from the greater curvature to fabricate a bipedicled flap. Most anterior chest wounds and virtually all mediastinal wounds can be covered with the omentum based on both sets of gastroepiploic vessels. The arc of transposition is increased when the omentum is based on a single pedicle, allowing coverage of virtually all chest-wall defects. The final method of increasing flap length involves division of the gastroepiploic arch and reliance on Barkow's marginal artery as collateral circulation to maintain flap viability. With regard to chest-wall reconstruction, we have included the omentum in the armamentarium of flaps used to cover mediastinal wounds. The omentum is our flap of choice for the reconstruction of most radiation injuries of the chest wall. The omentum may also be used to provide protection to visceral anastomoses, vascular conduits, and damaged structures in the chest, as well as to cover defects secondary to tumor excision or trauma. In brief, the omentum has proved to be a most dependable and versatile flap, particularly applicable to chest-wall reconstruction.
Conventional TRAM flap versus free microsurgical TRAM flap for immediate breast reconstruction.
Immediate breast reconstruction using the transverse abdominal myocutaneous island (TRAM) flap was performed in 54 patients over the past 3 years at our institution. This represented approximately 59 percent of patients undergoing all types of immediate breast reconstruction. In 10 patients, the abdominal island flap was transferred as a free flap based on the deep inferior epigastric pedicle. These patients were compared with the other 44 patients, in whom the flap was transferred using the conventional technique. The TRAM flap is well suited for immediate breast reconstruction because the procedure can be carried out simultaneously with mastectomy using separate operating teams and instruments. The operation is safe and relatively free of complications. The free TRAM group compared favorably with the conventional group in terms of complications, operating time, estimated blood loss, hospitalization, and return to functional baseline. The free TRAM flap appears to be as safe as the conventional technique with the advantages of a more limited rectus muscle harvest, improved medial contour of the breast due to the lack of tunneling, and perhaps a healthier flap because of the large donor vessels.
Clinical evaluation of flap viability with a dermal surface fluorometer.
A dermal surface fluorometer was used to monitor vascular perfusion in 22 patients who underwent reconstructive surgical procedures with a variety of flaps (e.g., skin flaps, musculocutaneous flaps, fasciocutaneous flaps, and Z-plasties). Sodium fluorescein (1.5 mg per kilogram of body weight) was administered intravenously at the completion of the operative procedure. Quantitative fluorescence readings were obtained at different points in each flap by means of the surface fluorometer (Fluoroscan). The readings were taken at several time intervals and compared with those of normal skin (control). A perfusion ratio was determined in each case according to the following formula: flap reading/(normal skin control reading X 100). Partial necrosis occurred in 4 patients, correlating with low fluorescein perfusion measurements. From our findings, it appears that a perfusion ratio of 15% or greater 10 minutes following injection will accurately predict tissue viability. No systemic reactions were observed in these patients. We believe that this minimally invasive technique should be of considerable assistance in the postoperative evaluation of flap viability.
Comparison of midazolam and diazepam for sedation during plastic surgery.
A randomized double-blind study was designed to compare midazolam, a rapid-acting water-soluble benzodiazepine, with diazepam for sedation when administered as an adjuvant to ketamine during local anesthesia. In the preliminary dose-ranging study, midazolam (0.05 to 0.15 mg/kg IV) was found to produce a spectrum of central nervous system activity (e.g., sedation, amnesia) that was similar to diazepam (0.1 to 0.3 mg/kg IV). However, the slope of midazolam's dose-response curve for sedation appeared to be steeper (i.e., a narrower therapeutic dosage range). In a comparative evaluation of their relative sedative-amnestic properties and recovery characteristics, the median effective doses of the two benzodiazepines were compared. Midazolam (0.1 mg/kg IV) was found to produce more profound sedation and amnesia than diazepam (0.2 mg/kg IV). Midazolam was associated with significantly less pain on injection and a lower incidence of postoperative venoirritation. Overall patient acceptance was higher with midazolam compared to diazepam. Finally, recovery characteristics were similar for the two benzodiazepines in our outpatient setting.
Lymphedema of the penis and scrotum.
The problem of genital lymphedema is commonly secondary to filariasis in most regions of the world. In the Western Hemisphere surgical manipulations usually exacerbate this significant problem. Lower leg edema may also result from these interventional procedures.
Pressure sore carcinoma.
The development of squamous cell carcinoma in pressure sores is a rare event, considering the high incidence of pressure sores within the elderly and paraplegic populations. The clinical courses of 10 patients with pressure sore carcinoma have been reviewed. The presence of a velvety, cauliflower-like growth on the surface of a long-standing pressure sore should alert the surgeon to the possibility of malignant degeneration. Most of these tumors are well-differentiated squamous cell carcinomas. Of the 10 patients, 8 (80%) died from massive local recurrence or distant metastases an average of 17 months after resection and flap closure despite having apparently localized disease. One patient was disease free when lost to follow-up at 2 years, and 1 patient is without evidence of recurrence or metastases 3 months postoperatively. Altered immunocompetence may play a role in the rapid progression and high mortality associated with this tumor after surgical manipulation.
An anatomic study of the venous drainage of the transverse rectus abdominis musculocutaneous flap.
The authors studied the venous drainage of the abdominal wall and its application to the transverse rectus abdominis musculocutaneous flap on 12 cadavers by injecting methylene blue and methyl methacrylate to follow the venous pathways. The nonvascular tissues of the specimens injected with methyl methacrylate were corroded away to show the three-dimensional arrangement of the vessels. We describe the veins of the anterior abdominal wall in relation to the transverse rectus abdominis musculocutaneous flap. The venous drainage of the transverse rectus abdominis musculocutaneous flap when used for breast reconstruction occurs from the cutaneous part of the flap to the inferior deep epigastric veins through vertical perforators that are mainly periumbilical. From there the flow is through the deep superior epigastric veins into the internal mammary vein. The deep inferior epigastric veins were found to have valves that prevent retrograde flow. In designing the flap, its safety is increased if it includes the periumbilical perforators. Thinning the flap should be done at the deep surface to preserve Scarpa's fascia and the superficial epigastric system.
A fasciocutaneous flap for vaginal and perineal reconstruction.
A skin and fascia flap from the medial thigh is proposed for vaginal and perineal reconstruction. Dissection, vascular injection, and radiographs of 20 fresh cadaver limbs uniformly demonstrated the presence of a communicating suprafascial vascular plexus in the medial thigh. Three to four nonaxial vessels were consistently found to enter the proximal plexus from within 5 cm of the perineum. Preservation of these vessels permitted reliable elevation of a 9 X 20 cm fasciocutaneous flap without using the gracilis muscle as a vascular carrier. Fifteen flaps in 13 patients were used for vaginal replacement and coverage of vulvectomy, groin, and ischial defects. Depending on the magnitude of the defect, simultaneous and independent elevation of the gracilis muscle provided additional vascularized coverage as needed. Our experience indicates that the medial thigh fasciocutaneous flap is a durable, less bulky, and potentially sensate alternative to the gracilis musculocutaneous flap for vaginal and perineal reconstruction.
Clinical progress in plastic and reconstructive surgery.
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Craniofacial reconstruction after tumor resections using vascularized outer table calvarial bone flaps.
The outer table of calvarium is a useful donor site for facial reconstruction after resection of tumors. Large defects, especially when associated with multiple operations and radiotherapy, are poor recipient beds for nonvascularized bone grafts. A technique for the transfer of vascularized outer table has been developed and used in 11 patients for reconstruction of tumor defects. Satisfactory correction of both functional and esthetic problems has been achieved with satisfactory long-term stability and low morbidity.
Anatomic basis for vascularized outer-table calvarial bone flaps.
The vascularization of the scalp and calvarium was studied in cadavers to better define the design of vascularized split- or full-thickness calvarial bone flaps. Selective dye injections of the superficial temporal and internal maxillary arteries established a horizontal and vertical network of vessels within and between each layer of the scalp. The periosteum of the frontoparietal region continues over the temporal aponeurosis as a separate, distinct layer, the innominate fascia, which is irrigated by numerous proximal branches of the superficial and deep temporal arteries. The periosteum can sustain the outer table of the calvarium by means of multiple small, vertical perforators. Between the periosteum and the outer table is a thin areolar layer of subperiosteum which continues beneath the temporal muscle. We feel that vascularized outer-table calvarial flaps can safely be pedicled using only the temporal aponeurosis, innominate fascia, and periosteum without including the galea or temporal muscle.
Vascularized outer-table calvarial bone flaps.
Based on an anatomic study of the vascularization of the calvarium in cadavers, a technique for the transfer of vascularized outer-table calvarial bone has been developed. The outer table of the calvarium receives numerous small perforators from its overlying periosteum. The periosteum is continuous with a distinct fascial layer overlying the temporal aponeurosis which we have termed the innominate fascia. Because of a network of anastomosing vessels from proximal branches of the superficial temporal artery and perforating branches of the deep temporal artery, the outer table of the calvarium can be carried on a pedicle which contains the temporal aponeurosis, innominate fascia, and periosteum. Thirty-seven vascularized outer-table calvarial bone flaps have been performed for a variety of craniofacial reconstructive deformities. Remarkable stability and lack of resorption have led the authors to favor this method of reconstruction particularly in poorly vascularized or previously infected recipient beds.