The use of 5% mafenide acetate solution in the postgraft treatment of necrotizing fasciitis.

Twenty-nine patients with necrotizing fasciitis who were treated with 5% mafenide acetate solution (MAS) as an adjunct after grafting were compared with 45 patients treated without MAS. Statistical analysis of differences was obtained through P values by chi2 testing. The MAS+ (M) and MAS- (C) groups were similar in percent skin deficit (M = 7.5%; C = 9.8%), with the extremity being the most common area of infection. Streptococcus was the most common single organism but polymicrobial infections were the most prevalent (M = 48%; C = 58%). Patients with necrotizing fasciitis treated with MAS had fewer debridements per patient (M = 3.7; C = 5.4), fewer closure procedures (average per patient: M = 1.2; C = 1.73) and a higher percent of first-time closures (83 vs 59%; chi2 = 4.26; P = 0.039). There is a trend toward a lower mortality rate (3.4 vs 13%; chi2 = 2.00; P = 0.158). We conclude that MAS is a useful adjunct in necrotizing fasciitis wound care protocols.

Duration of antibiotic prophylaxis in high-risk patients with penetrating abdominal trauma: a prospective randomized trial.

To evaluate the effect of varying durations of antibiotic prophylaxis in trauma patients with multiple risk factors for postoperative septic complications, a prospective randomized trial was undertaken at an urban level I trauma center. The inclusion criteria were full-thickness colon injury and one of the following: (1) Penetrating Abdominal Trauma Index > 25, (2) transfusion of 6 units or more of packed red blood cells, or (3) more than 4 hours from injury to operation. Patients were randomly assigned to a short course (24 hours) or a long course (5 days) of antibiotic therapy. All patients received 2 g cefoxitin en route to the operating room and 2 g intravenously piggyback every 6 hours for a total of 1 day vs. 5 days. Sixty-three patients were equally divided into short-course (n = 31) and long-course (n = 32) therapy. This was a high-risk patient population, as assessed by the mean Penetrating Abdominal Trauma Index (33), number of patients with multiple blood transfusions (51 of 63; 81%), number of patients with an Injury Severity Score greater than 15 (37 of 63; 59%), number of patients with destructive colon wounds requiring resection (27 of 63; 43%), and number of patients requiring postoperative critical care (37 of 63; 59%). Differences in intra-abdominal (1-day, 19%; 5-days, 38%) and extra-abdominal (1-day, 45%; 5-days, 25%) infection rates did not achieve statistical significance. There continues to be no evidence that extending antibiotic prophylaxis beyond 24 hours is of benefit, even among the highest risk patients with penetrating abdominal trauma. A large, multi-institutional trial will be necessary to condemn this common practice with statistical validity.

High-frequency percussive ventilation improves oxygenation in patients with ARDS.

STUDY OBJECTIVES: To evaluate changes in respiratory and hemodynamic function of patients with ARDS and requiring high-frequency percussive ventilation (HFPV) after failure of conventional ventilation (CV). DESIGN: Retrospective case series. SETTING: Surgical ICU (SICU) and medical ICU (MICU) of an academic county facility. MEASUREMENTS AND RESULTS: Thirty-two consecutive patients with ARDS (20 from SICU, 12 from MICU) who were unresponsive to at least 48 h of CV and were switched to HFPV were studied. Data on respiratory and hemodynamic parameters were collected during the 48 h preceding and the 48 h after institution of HFPV and compared. Between the period of CV and the period of HFPV, the ratio of PaO2 to the fraction of inspired oxygen (F(IO2)) increased ([mean+/-SE] 130+/-8 vs. 172+/-17; p = 0.027), peak inspiratory pressure (PIP) decreased (39.5+/-1.7 vs. 32.5+/-1.9 mm Hg; p = 0.002), and mean airway pressure(MAP) increased (19.2+/-1.2 vs. 27.5+/-1.4 mm Hg; p<0.001). The rate of change of PaO2/F(IO2) per hour was also significantly improved between the two periods. The same changes in PaO2/F(IO2), PIP, and MAP were observed when the last value recorded while the patients were on CV was compared with the first value recorded after 1 h of HFPV. This improvement was sustained but not amplified during the hours of HFPV. The patterns of improvement in these three parameters were similar in SICU and MICU patients as well as in volume-control and pressure-control patients. There were no changes in hemodynamic parameters. CONCLUSION: The HFPV improves oxygenation by increasing MAP and decreasing PIP. This improvement is achieved soon after institution of HFPV and is maintained without affecting hemodynamics.

Multicenter study of noninvasive monitoring systems as alternatives to invasive monitoring of acutely ill emergency patients.

BACKGROUND: Recent reports showed lack of effectiveness of pulmonary artery catheterization in critically ill medical patients and relatively late-stage surgical patients with organ failure. Since invasive monitoring requires critical care environments, the early hemodynamic patterns may have been missed. Ideally, early noninvasive hemodynamic monitoring systems, if reliable, could be used as the "front end" of invasive monitoring to supply more complete descriptions of circulatory pathophysiology. OBJECTIVES: To evaluate the accuracy and reliability of noninvasive hemodynamic monitoring consisting of a new bioimpedance method for estimating cardiac output combined with arterial BP, pulse oximetry, and transcutaneous PO2 and PCO2; we compared this system of noninvasive monitoring with simultaneous invasive measurements to evaluate circulatory deficiencies in acutely ill patients shortly after hospital admission where invasive monitoring was not readily available. We also preliminarily explored early differences in temporal hemodynamic patterns of survivors and nonsurvivors. DESIGN AND SETTING: Prospective comparison of simultaneous invasive and noninvasive measurements of circulatory function with retrospective analysis of data in university-run county hospitals, university hospitals and affiliated teaching hospitals, and a community private hospital. PATIENTS: We studied 680 patients, including 139 severely injured or hemorrhaging patients in the emergency department (ED), 129 medical (nontrauma) patients on admission to the ED, 274 high-risk surgical patients intraoperatively, and 138 patients recently admitted to the ICU. RESULTS: A new noninvasive impedance device provided cardiac output estimations under conditions in which invasive thermodilution measurements were not usually applied. There were 2,192 simultaneous bioimpedance and thermodilution cardiac index measurements; the correlation coefficient, r = 0.85, r2 = 0.73, p < 0.001. The precision and bias was -0.124+/-0.75 L/min/m2. Both invasive and noninvasive monitoring systems provide similar information and identified episodes of hypotension, low cardiac index, arterial hemoglobin desaturation, low transcutaneous O2, high transcutaneous CO2, and low oxygen consumption before and during initial resuscitation. The limitations of noninvasive systems were described. CONCLUSIONS: Noninvasive monitoring systems gave continuous displays of physiologic data that provided information allowing early recognition of low flow and poor tissue perfusion that were more pronounced in the nonsurvivors. Noninvasive systems may be acceptable alternatives where invasive monitoring is not available.

Histologic alterations in dermal repair after thermal injury effects of topical angiotensin II.

Previously, we determined that quantitative assessment of epithelialization of the burn site could be performed using quantitative immunohistochemistry with an antibody to the protein cyclin. In this study, the effect of administration of angiotensin II (AII) on two histologic parameters of healing-the number of vascular channels at the burn site and the number of cells proliferating in hair follicles at the edge of the burn and within the burn-were evaluated. Beginning on day 4, vascular channels were noted within the burn site. Significantly more channels were noted in the burns treated with AII than those treated with placebo. With the exception of 3 postinjury days, this increase continued through day 17. Thereafter, the number of vascular channels peaked, and no differences were noted between control and treated burns. The number of cells proliferating in the hair follicle was also evaluated. At the edge of the burn, on average, 126 cells per microscope field (10x) were undergoing proliferation in the AII-treated burn on days 1 through 16 after burn injury. This is approximately a 50% increase over the number of cells proliferating in the placebo-treated burns. On day 12 (approximately 5 days before that observed in control burns), this AII-dependent proliferative response began to increase and peaked on day 19 at a level comparable to control. Thereafter, the proliferative response remained at this level through day 28. Within the area of the burn on days 1 through 15, 21 cells per medium power field on average (approximately 50% more than control) were undergoing proliferation. As on the edge of the burn, an AII-dependent increase in the number of cells proliferating in the hair follicles was observed during the latter phase of healing (on day 16 after the initiation of injury). However, unlike the edge of the burn, administration of AII led to a continued increase (approximately 50%) in the number of cells per field undergoing proliferation. AII increased neovascularization and cellular proliferation after burn injury. Through an increase in these two cellular events, AII may in turn accelerate healing of tissues after thermal injury.

Necrotizing fasciitis of the face.

Necrotizing fasciitis (NF) is a rapidly progressive soft tissue infection with high morbidity and mortality rates. Its occurrence in the head and neck region is uncommon, the majority of reported cases being limited to involvement of the neck, usually from infections of dental or pharyngeal origin. Involvement of the face from NF is rare; only 35 such cases have been reported in the literature since 1960. It is not only associated with a high mortality but can also result in severe disfigurement of the face, posing challenging reconstructive problems. Successful management of facial NF requires early diagnosis, prompt institution of broad spectrum antibiotics, aggressive surgical debridement to control the infection, and reconstruction of the resultant soft tissue defects. This report describes four additional cases of facial necrotizing fasciitis. One of the four patients died as a result of sepsis and multi-organ system failure. Two of the three surviving patients had significant facial disfigurement. A comprehensive review of the facial NF cases reported in the literature is also provided. Based on our experience with facial NF and the results of all previous case reports, the clinical manifestations, pathogenesis, and management of this disease are discussed.

Expression of cyclin protein after thermal skin injury in a guinea pig model.

In this study, an immunohistochemical stain for cyclin was used to quantitate proliferating elements in hair follicles at the edge of and within thermal burn areas. Biopsy specimens from thermal injury in the guinea pig (day 1 through day 28) were sectioned and stained with MIB-1 antibody, which recognizes cyclin, a protein expressed during epithelial cell proliferation. At the edge of the burn, 89 +/- 6.1 (SD) cells per medium power field (x 10, mpf) were MIB-1-positive on days 1 through 16. On day 17, the number of positive cells increased, reaching peak values on days 20 to 28 (271 +/- 12.7 cells/mpf). Within the burn, minimal staining was observed from day 1 to day 15 (12.7 +/- 1.6 cells/mpf). Thereafter the number of MIB-1-positive cells increased and plateaued with an average of 96.4 +/- 9.0 cells/mpf on days 20 through 28. In conclusion, immunohistochemical staining of dermal biopsy specimens with MIB-1 antibody may provide a quantitative method for the evaluation of tissue damage and healing after thermal injury.

The pattern of fungal infections in critically ill surgical patients.

There continues to be difficulty making the clinical distinction between fungal colonization and systemic infection in critically ill surgical patients. This distinction is important, given the potential risks of aggressive antifungal therapy. In order to evaluate the significance of fungal infections by various sites, we retrospectively reviewed the clinical courses of patients with cultures positive for fungi (Candida species or Torulopsis glabrata) in the SICU of LAC + USC Medical Center from January 1992-December 1993. There were 129 patients who were culture positive for Candida (110 patients) or Torulopsis glabrata (19 patients). There were 187 positive cultures. Fifty-five patients (43%) had systemic fungal infections (two or more sites, or fungemia). The proportion of patients with positive cultures from any given site going on to develop systemic infections was similar (wound, 49 per cent; urine, 54 per cent; sputum, 57 per cent; drain, 68 per cent; P = 0.61, NS). The mortality for SICU patients with systemic fungal infection was significantly increased (36.3% versus 10.5%, P < 0.05) when compared with SICU patients in general. No significant increase in mortality was seen in patients with single site isolation (13.5% versus 10.5%, P = 0.52). This study suggests that although systemic fungal infection is associated with increased mortality in SICU patients, no single site of isolation is superior to others in predicting which patients are likely to develop systemic infection. Prospective studies with antifungal agents with reduced toxicity are justified in patients with single site isolation.

Mesenchymal commitment to digital joint formation.

Temporal and spatial commitment of in vivo and in vitro mammalian digital joint development were characterized in a murine model. Alcian blue and alizarin red staining were used to label proteoglycans of cartilage matrix and mineralized matrix in both whole mounts and histological sections. Mesenchymal differentiation toward a joint fate was identified by a lack of matrix deposition in islands of joint precursor cells between phalangeal precursors, and localized lysosomal enzyme activity was later demonstrated in these regions during formation of the joint cavity. Organ-cultured forelimbs and in vivo specimens demonstrated analogous digital joint morphological trends. With a defined developmental window, reverse transcription, polymerase chain reaction, demonstrated differential gene expression of transforming growth factor-beta isotypes, aggrecan core protein, and type II collagen, suggesting a role for transforming growth factor-beta in directing digital joint development.

Radical forequarter amputation with hemithoracectomy and free extended forearm flap: technical and physiologic considerations.

BACKGROUND: A radical forequarter amputation with partial chest wall resection (one to four ribs) has been reported for benign and malignant lesions involving the shoulder and chest wall region. Concerns about reconstruction and postoperative pulmonary function have previously limited more extensive chest wall resections. The current report describes the first case in which a complete unilateral anterior and posterior chest wall resection and pneumonectomy (hemithoracectomy) accompany a forequarter amputation. A novel reconstructive technique used the full circumference of the forearm tissue with an intact ulna as a free osseomyocutaneous flap. METHODS: In this case, a 21-year-old patient presented with an extensive recurrent desmoid tumor that involved the shoulder, brachial plexus, subclavian vein, and chest wall from the lateral sternal border to the midportion of the scapula and down to the eighth rib. The operative technique involved removal of the entire right hemithorax from the midline sternum to the transverse process posteriorly, down to the ninth rib inferiorly. Due to the absence of a rigid hemithorax, the uninvolved ipsilateral lung was also removed. The forearm flap was prepared before final separation of the specimen and division of the subclavian vessels. RESULTS: Postoperatively, the patient maintained excellent oxygenation without atelectasis or fever and was extubated on the 15th postoperative day. As expected after pneumonectomy, significant decreases from preoperative to immediate postoperative values were noted for the vital capacity (VC) (from 4.87 L to 1.29 L), forced 1-s expiratory volume (FEV1) (from 3.77 L to 1.02 L), and inspiratory capacity (IC) (3.33 l to 0.99 l). Rehabilitation included a specially designed external prosthesis to provide cosmesis and prevent scoliosis. By the 15th postoperative week the patient had returned to normal social and physical activities, with a gradual improvement in all respiratory parameters: VC 1.52 L, FEV1 1.29 L, IC 1.04 L. There has been no evidence of tumor recurrence at 1 year. CONCLUSIONS: This report provides evidence that a complete hemithoracectomy, pneumonectomy, and forequarter amputation can be safely performed for selective tumors involving the shoulder region with extensive chest wall invasion. Reconstruction may be achieved with an extended forearm osseomyocutaneous free flap with an excellent functional outcome.

The natural history of alloplastic implants in orbital floor reconstruction: an animal model.

We developed a new animal model to recreate the condition of an open fracture in communication with the maxillary sinus. We then studied wound healing of the sinus wall structures following fracture in the presence of an alloplastic implant. This model is designed to simulate the alloplastic repair of an orbital floor fracture in humans. The New Zealand White rabbit was used as the animal model. Standardized 8-mm defects were made bilaterally in the maxillary sinuses to include bone and mucosa in 21 rabbits. Two different implants were placed in the soft-tissue pockets to obturate the defects, exposing one surface of the implant to the open sinus. Medpor porous polyethylene and silicone implants were compared. Animals were killed at 1, 2, 3, and 4 weeks and at 2, 4, and 5 months after implantation. Gross examination of the specimens for the amount of mucosal closure and implant tissue fixation was performed. Histological sections were evaluated for bone and soft-tissue morphology juxtaposed to the implant. Complete closure of the mucosal defect was demonstrated with both types of implants. Medpor implants showed both vascular and soft-tissue ingrowth into its pores by week 1. Bone ingrowth was seen by week 3. Closure of the Medpor obturated defects occurred more rapidly than in the silicone group (p < 0.004 at week 4). The Medpor implants demonstrated bone and soft-tissue fixation, and mature overlying mucosa was reconstituted over the defects. Silicone implants demonstrated a fibrous tissue reaction within 1 week of implantation and they never became fixed to bone or soft tissue.(ABSTRACT TRUNCATED AT 250 WORDS)