A multi-institutional, propensity-score-matched comparison of post-operative outcomes between general anesthesia and monitored anesthesia care with intravenous sedation in umbilical hernia repair.

PURPOSE: Monitored anesthesia care with intravenous sedation (MAC/IV), recently proposed as a good choice for hernia repair, has faster recovery and better patient satisfaction than general anesthesia; however the possibility of oversedation and respiratory distress is a widespread concern. There is a paucity of the literature examining umbilical hernia repairs (UHR) and optimal anesthesia choice, despite its importance in determining clinical outcomes. METHODS: A retrospective analysis of anesthesia type in UHR was performed in the National Surgical Quality Improvement Program 2005-2013 database. General anesthesia and MAC/IV groups were propensity-score-matched (PSM) to reduce treatment selection bias. Surgical complications, medical complications, and post-operative hospital stays exceeding 1 day were the primary outcomes of interest. Pre-operative characteristics and post-operative outcomes were compared between the two anesthesia groups using univariate and multivariate statistics. RESULTS: PSM removed all observed differences between the two groups (p > 0.05 for all tracked pre-operative characteristics). MAC/IV cases required fewer post-operative hospital stays exceeding 1 day (3.5 vs 6.3 %, p < 0.001). Univariate analysis showed that overall complication rate did not differ (1.7 vs 1.8 %, p = 0.569), however MAC/IV cases resulted in fewer incidences of septic shock (<0.1 vs 0.1 %, p = 0.016). After multivariate logistic regression, MAC/IV was revealed to yield significantly lower chances of overall medical complications (OR = 0.654, p = 0.046). CONCLUSION AND RELEVANCE: UHR under MAC/IV causes fewer medical complications and reduces post-operative hospital stays compared to general anesthesia. The implications for surgeons and patients are broad, including improved surgical safety, cost-effective care, and patient satisfaction.

The role of tissue expansion in the management of large congenital pigmented nevi of the forehead in the pediatric patient.

The authors present a cohort of 21 consecutive patients who had congenital pigmented nevi covering 15 to 65 percent of the forehead and adjacent scalp and who were treated at their institution within the last 12 years. All patients were treated with an expansion of the adjacent texture- and color-matched skin as the primary modality of treatment. The median age at presentation was approximately 1 year; mean postoperative follow-up was 4 years. Nevi were classified according to the predominant anatomic areas they occupied (temporal, hemiforehead, and midforehead/central); some of the lesions involved more than one aesthetic subunit. The authors propose the following guidelines: (1) Midforehead nevi are best treated using an expansion of bilateral normal forehead segments and advancement of the flaps medially, with scars placed along the brow and at or posterior to the hairline. (2) Hemiforehead nevi often require serial expansion of the uninvolved half of the forehead to minimize the need for a back-cut to release the advancing flap. (3) Nevi of the supraorbital and temporal forehead are preferentially treated with a transposition of a portion of the expanded normal skin medial to the nevus. (4) When the temporal scalp is minimally involved with nevus, the parietal scalp can be expanded and advanced to create the new hairline. When the temporoparietal scalp is also involved with nevus, a transposition flap (actually a combined advancement and transposition flap because the base of the pedicle moves forward as well) provides the optimal hair direction for the temporal hairline and allows significantly greater movement of the expanded flap, thereby minimizing the need for serial expansion. (5) Once the brow is significantly elevated on either the ipsilateral or contralateral side from the reconstruction, it can only be returned to the preoperative position with the interposition of additional, non-hair-bearing forehead skin. Expansion of the deficient area alone will not reliably lower the brow once a skin deficiency exists. (6) In general, one should always use the largest expander possible beneath the uninvolved forehead skin, occasionally even carrying the expander under the lesion. Expanders are often overexpanded.

The use of subatmospheric pressure dressing therapy to close lymphocutaneous fistulas of the groin.

Groin lymphorrhea is an uncommon but serious complication of vascular and cardiac surgery as well as interventional procedures that cannulate the femoral vessels. Treatment options are somewhat controversial. For lymphocutaneous fistulas, a commonly used current modality is early surgical ligation with the assistance of blue-dye staining of the lymphatic anatomy. The purpose of this case series is to give the first description of a new, less invasive, approach using subatmospheric pressure dressing therapy for the treatment of the challenging problem of lymphocutaneous fistulas of the groin.

Macrophage colony-stimulating factor accelerates wound healing and upregulates TGF-beta1 mRNA levels through tissue macrophages.

Macrophage colony-stimulating factor (M-CSF) is produced by many cell types involved in wound repair, yet it acts specifically on monocytes and macrophages. The monocyte-derived cell is thought to be important in wound healing, but the importance of the role of tissue macrophages in wound healing has not been well defined. Dermal ulcers were created in normal and ischemic ears of young rabbits. Either rhM-CSF (17 microg/wound) or buffer was applied to each wound. Wounds were bisected and analyzed histologically at Days 7 and 10 postwounding. The amounts of epithelial growth and granulation tissue deposition were measured in all wounds. The level of increase of TGF-beta1 mRNA level in M-CSF-treated wounds was examined using competitive RT-PCR. M-CSF increased new granulation tissue formation by 37% (N = 21, P < 0.01) and 50% (P < 0.01) after single and multiple treatments, respectively, in nonischemic wounds. TGF-beta1 mRNA levels in rhM-CSF-treated wounds increased 5.01-fold (N = 8) over vehicle-treated wounds under nonischemic conditions. In contrast, no effect could be detected in ischemic wounds treated with rhM-CSF, and these wounds only showed a 1.66-fold increase in TGF-beta1 mRNA levels when compared to ischemic wounds treated with vehicle alone. GAPDH, a housekeeping gene, showed no change. As mesenchymal cells lack receptors for M-CSF, the improved healing of wounds treated with topical rhM-CSF must reflect a generalized enhancement of activation and function of tissue macrophages, as demonstrated by upregulation of TGF-beta. The lack of effect under ischemic conditions suggests that either macrophage activity and/or response to M-CSF is adversely affected under those conditions; this may suggest the pathogenesis of impaired wound healing at the cellular level.

Interaction between the insulin-like growth factor family and the integrin receptor family in tissue repair processes. Evidence in a rabbit ear dermal ulcer model.

We have determined previously that IGF-I is dependent on the presence of IGF binding protein-1 (IGFBP-1) to act as a wound healing agent. We sought to determine the mechanism whereby IGFBP-1 is able to enhance IGF-I bioactivity. As IGFBP-1 binds both the alpha5beta1 integrin as well as IGF-I in vitro, we asked which of the following interactions were important: (a) the ability of IGFBP-1 to interact with an integrin receptor, and/or (b) the binding of IGF-I by IGFBP-1. We used an IGF-1 analogue (des(1-3)IGF-I) with a > 100-fold reduction in affinity for IGFBP-1 as well as an IGFBP-1 mutant (WGD-IGFBP-1) which does not associate with the alpha5beta1 integrin to selectively abrogate each of these interactions. We also tested the ability of IGFBP-2, a related binding protein which has an arginine-glycine-aspartate sequence but does not associate with integrin family members, to enhance IGF-I bioactivity. Full-thickness dermal wounds were created on rabbit ears; various combinations of native IGF-I, native IGFBP-1, native IGFBP-2, and their respective analogues/mutants were applied to each wound. Wounds were harvested 7 d later for analysis. Only native IGF-I in combination with native IGFBP-1 was effective as a wound healing agent, enhancing reepithelialization and granulation tissue deposition by 64+/-5 and 83+/-12% over controls (P = 0.008 and 0.016, respectively). The same doses of IGF-I/WGD-IGFBP-1, des(1-3)IGF-I/IGFBP-1, and IGF-I/IGFBP-2 were ineffective. We propose that IGF-I physically interacts with IGFBP-1 and that IGFBP-1 also binds to an integrin receptor, most likely the alpha5beta1 integrin. This interaction is unique to IGFBP-1 as the closely related IGFBP-2 had no effect, a finding consistent with its inability to bind to integrin receptors. Our results suggest that activation of both the IGF-I receptor and the alpha5beta1 integrin is required for IGF-I to stimulate wound healing.

Efficacy of positively charged ion exchange beads in radiation-impaired models of wound healing.

We have previously demonstrated in a rat surgical incision model that charged dextran beads enhance wound repair in a charge-specific manner: positively charged beads increased wound breaking strength (WBS), whereas neutral or negatively charged beads were ineffective. The present work extends these observations into two models of radiation-impaired healing. One hundred five rats were divided into three groups: group 1, controls, no irradiation; group 2, total body irradiation; group 3, surface irradiation. Three days after irradiation, 0.1 ml of a suspension of either positively charged beads, neutral beads, or vehicle alone was applied to paired 6-cm incisions on the dorsum of the rats. Ten days later, wounds were excised and sample strips were harvested for determination of WBS and for histological analysis. Following total body irradiation, positively charged beads enhanced WBS 84% compared to beadless controls. When results with positively charged beads were compared to those with neutral beads, a 39% increase in WBS was noted. Healing, as measured by WBS, was more impaired in surface-irradiated animals, but when results with positively charged beads were compared with those obtained with neutral beads, a similar degree of healing (+38%) was noted. Neutral beads proved ineffective. Histology revealed that neutral beads evoked a modest foreign body response, yet there was a consistently greater clustering of giant cells around positively charged beads in wound sites. This paralleled in vitro experiments demonstrating increased monocyte aggregation around positively charged beads in tissue culture. The results suggest that positively charged ion exchangers, such as these positively charged beads, perhaps through their recruitment and/or activation of wound macrophages, may have a potential clinical role in the treatment of impaired wounds.

Keratinocyte growth factor induces granulation tissue in ischemic dermal wounds. Importance of epithelial-mesenchymal cell interactions.

BACKGROUND: Keratinocyte growth factor acts specifically on epithelial cells and is presumed to play an important role in tissue repair. OBJECTIVE: To examine the wound-healing effects of keratinocyte growth factor under hypoxic conditions in vivo and in vitro. DESIGN AND INTERVENTIONS: Dermal ulcers were created in the ischemic ears of 40 anesthetized young female rabbits. Either recombinant keratinocyte growth factor (rKGF) or buffer was applied to each wound. Wounds were bisected and analyzed histologically at days 7 and 10 after wounds were created. For the in vitro study, normal keratinocytes were treated with rKGF (20 ng/mL) and cultured under hypoxic (3.5% oxygen) conditions. The conditioned media were collected at 48 and 72 hours. MAIN OUTCOME MEASUREMENTS: The amount of epithelial growth and deposition of granulation tissue were measured in all wounds. The amount of transforming growth factor alpha in keratinocyte-conditioned media was measured by using a sensitive radioimmunoassay. A proliferation assay of dermal fibroblasts, treated with conditioned media, was also performed under 3.5% oxygen culture conditions. RESULTS: The rKGF (range, 5-40 micrograms per wound) that was applied significantly increased new epithelium by greater than 70% (P = .03) at days 7 and 10 after wounds were created. A significant increase in new granulation tissue formation (170%) was also observed in rKGF-treated wounds at day 10, at a dose of 40 micrograms per wound (P < .002). The amount of transforming growth factor alpha protein in the conditioned media that were treated with rKGF (20 ng/mL) increased by 26.8% and 171% at 48 and 72 hours, respectively, over that of controls. The conditioned media from rKGF-treated keratinocytes, grown for 72 hours, resulted in a 51% increase in the proliferation of primary rabbit dermal fibroblasts. CONCLUSION: Keratinocyte growth factor enhances the wound-healing process of ischemic ulcers, indicating that epithelial-mesenchymal cell interactions are critical for the healing of wounds under ischemic conditions and possibly under normal conditions as well.

Differential effects of oxygen on human dermal fibroblasts: acute versus chronic hypoxia.

The observation that many chronic wounds are ischemic has spurred a series of studies evaluating the response of cells exposed to hypoxia. To date, these studies have shown largely beneficial effects from hypoxia, such as increased cellular replication and procollagen synthesis. These findings are counter-intuitive from a clinical standpoint because cellular growth and synthetic function are known to be retarded in chronic ischemic wounds. We have established an in vitro system in which human dermal fibroblasts grown chronically at 5 +/- 3 mm Hg will proliferate at a rate three times slower than those fibroblasts grown under standard culture conditions (namely an oxygen partial pressure of 150 mm Hg). No phenotypic changes are noted in chronically hypoxic cells, and the growth-retarding effects are reversible when the cells are returned to standard oxygen conditions. Competitive reverse transcription-polymerase chain reaction showed that acute exposure to hypoxia (up to 1 week) results in a 6.3-fold increase in the relative expression of transforming growth factor-beta1 messenger RNA, whereas chronic exposure to hypoxia leads to a 3.1-fold decrease in this message. Collagen production measured at both the mRNA and protein level is also decreased in the setting of chronic hypoxia. We propose that this system may be the most appropriate setting for studying the role of oxygen on dermal fibroblasts in ischemic, nonhealing wounds.

Effects of insulin-like growth factor-I and insulin-like growth factor binding protein-1 on wound healing in a dermal ulcer model.

The effects on wound healing of insulin-like growth factor-I with and without insulin-like growth factor binding protein-1 were studied in a rabbit ear dermal ulcer model under both nonischemic and ischemic conditions. Wounds 6 mm in diameter were made on the ventral surface of rabbit ears for a total of 272 wounds in the nonischemic group and 77 wounds in the ischemic group. Insulin-like growth factor-I in varying doses (1 to 43 microg) and in combination with varying molar ratios of the binding protein were added at time of wounding to each wound. Wounds were analyzed histomorphometrically on day 7 after wounding. We found that insulin-like growth factor-I or binding protein alone at varying doses did not have any effects on wound healing parameters. Low to moderate doses (1 microg and 4 microg, respectively) of the combination of insulin-like growth factor-I with the binding protein in a molar ratio of 5:1 or 11:1 showed a 52% increase (p < 0.05) in new granulation tissue in the nonischemic model compared with controls but did not significantly augment new granulation tissue formation in the ischemic wound model. A high dose (43 microg) at a 10:1 molar ratio of growth factor to binding protein was required to elicit significantly enhanced wound healing in ischemic wounds. These results indicate that insulin-like growth factor binding protein-1 modulates the effects of insulin-like growth factor-I in promoting wound healing in vivo and that the combination is a highly effective vulnerary compound with effects comparable in magnitude with other growth factors previously tested in this model.