Performance and emission characteristics of a low heat rejection engine with different air gap thicknesses with Jatropha oil based bio-diesel.

The research work on alternate fuels has been the topic of wider interest in the context of depletion of fossil fuels and increasing of pollution levels of the engines with conventional fossil fuels. Alcohols and vegetable oils are considered to replace diesel fuels as they are renewable in nature. However, use of alcohols in internal combustion engines is limited in India, as these fuels are diverted to PetroChemical industries and hence much emphasis is given to the non-edible vegetable oils as alternate fuels in internal combustion engines. However, the drawbacks of low volatility and high viscosity associated with non-edible vegetable oils call for hot combustion chamber, provided by low heat rejection (LHR) diesel engine. Investigations are carried out on a LHR diesel engine with varied air gap thicknesses and injection pressures with jatropha oil based bio-diesel at normal temperature. Performance is improved with high degree of insulation with LHR engine with vegetable oil in comparison with conventional engine (CE) with pure diesel operation.

Microvascular steal phenomenon in lower extremity reconstruction.

Macrovascular bypass procedures and microvascular free tissue transfer have resulted in dramatic improvements in lower limb salvage. Although vascular steal is a well-documented phenomenon in the surgical literature, there is a paucity of information on its potential impact in microvascular surgery, particularly in relation to lower extremity reconstruction in the elderly patient with peripheral vascular disease. We report three cases of lower extremity reconstruction using microvascular free tissue transfer in which the free flap survived but the distal extremity suffered progressive ischemic necrosis. A retrospective analysis of these cases defines the conditions in which microvascular steal phenomenon may adversely influence lower limb salvage.

Optimal management of inguinal vascular graft infections.

Vascular graft infections demand serious attention due to the potential for mortality or limb loss. Management modalities range from conservative wound debridement and drainage to graft resection and extra-anatomical revascularization. A retrospective chart review was conducted to evaluate wound complications in patients who underwent inguinal vascular bypass in an attempt to define the incidence of wound complications and guidelines for their management. Vascular operations involving femoral anastomoses were performed on 1,637 patients; 58 wound infections occurred in 57 patients (3.5%) over an 8-year period at our institution. There were 16 graft infections in 15 of these 57 patients (0.92%). Ten patients were treated with local muscle flaps, 1 with a fasciocutaneous thigh flap, and 5 with graft excision and either extra-anatomical bypass or amputation. Local flap coverage appears to be as effective as graft excision for the treatment of inguinal vascular graft infections. An algorithm for optimal management of these infections is presented.

Delayed debulking of free muscle flaps for aesthetic contouring debulking of free muscle flaps.

Although denervated muscle and myocutaneous free flaps atrophy over a period of time, when used for surface coverage they may remain bulky, resulting in a less than optimal aesthetic result. With the availability of a number of donor sites, soft tissue defects can often be reconstructed with like tissue in a single stage. Even though the goal of all plastic surgeons is to achieve a good cosmetic result, special circumstances might dictate that need take precedence over form. We have had six cases where a bulky muscle was used to achieve well vascularised coverage. After wound closure had been successfully accomplished, a secondary debulking procedure was performed safely for a final acceptable aesthetic result.

Amputation stump salvage using a "banked" free-tissue transfer.

A free radical forearm flap was salvaged from a nonreplantable amputated extremity and banked on the ipsilateral chest wall. Later, the flap was simply rotated to provide coverage of the proximal humeral stump, eliminating the need for a second microvascular procedure.

Free-tissue transfers for limb salvage utilizing in situ saphenous vein bypass conduit as the inflow.

Using vein grafts to bypass sclerotic and occluded arterial segments is a well-established technique in vascular surgery. For infrapopliteal bypass, autogenous veins have better patency rates than synthetic grafts. Although not resolved, in situ bypasses seem to be better than reversed bypasses, especially for "far away" segments. Although the etiology is not understood, it is a well-known clinical finding that sclerosis affects arteries more than the veins and, as a whole, is more advanced in lower extremities compared with the trunk and upper extremities. Our experience with eight patients in whom critical soft-tissue defects were covered with free-tissue transfers in severely compromised lower extremities utilizing the in situ saphenous vein bypass as the inflow is presented. Simultaneous bypass and free-tissue transfers were performed in seven and delayed free-tissue transfer was done in one. Follow-up ranged from 6 months to 3 years. To date, two patients underwent amputations. Five patients are able to maintain bipedal ambulation. One patient is wheelchair-bound with intact lower extremities. In well-selected patients, this procedure may offer an alternative treatment to amputation. However, because of the complexity of these combined procedures, we strongly urge careful patient selection.

Free temporoparietal flap in burn reconstruction.

A series of 12 patients with deep burns resulting in exposed bones, joints, and tendons, in whom temporoparietal free flaps were used for reconstruction, are presented. Flap loss was 8.3%; good and satisfactory results were achieved in 91.7% of healed defects. Patients with large total body surface area burns are severely compromised, and the use of free flaps requiring prolonged periods of anesthesia and surgery should be a judicious decision. Prior to the availability of free flaps, most of these patients are left with chronic wounds and compromised functional results. Although our experience is limited, we think that in well-selected cases a one-stage reconstruction with free tissue transfer is expeditious, safe, and economical.

Use of vein-patch angioplasty in microvascular tissue transfers.

Vein-patch angioplasty is a well-established technique in vascular surgery to reduce the critical narrowing of the arteriotomy site. In microsurgical end-to-side anastomosis, although the arteriotomy is not closed, it is not known if anastomosis through a sclerotic segment contributes to narrowing at the anastomotic site. It is certainly technically difficult to perform a microanastomosis with fine sutures through a sclerotic segment. Two cases are illustrated in which vein-patch angioplasties were successfully used for microsurgical anastomoses.

Large vascular plexiform neurofibroma of scalp: excision and coverage with free tissue transfer.

Diffuse neurofibroma (paraneurofibroma) is an unusual variant of neurofibroma in which the tumor cells diffusely infiltrate beyond the usual well-circumscribed boundary. Histological features of the tumor include both typical and plexiform neurofibroma. Although benign, diffuse vascularity with the possibility of life-threatening hemorrhage dictates treatment. The combination of preoperative angiography, wide surgical excision, and resurfacing the defect with well-vascularized tissue offers one-stage reconstruction and possible cure.

Use of temporoparietal fascia free flap in digital reconstruction.

Temporoparietal fascia free flap is an excellent source for resurfacing soft tissue defects of the hand and fingers. Because of the reliable anatomical bifurcation of the superficial temporal vessels, this flap can be very useful in simultaneous reconstruction of more than one digit without having to create a temporary syndactyly.

Fluorometric analysis of an attempt to reclaim ischemic flaps in rats with Fluosol.

An experiment was designed to answer two questions as they apply to random skin-flap survival: Is there a therapy that can improve random skin-flap survival when given postoperatively? And if so, when does one start such a therapy? Fluosol-DA 20% (Fluosol) has increased random skin-flap survival when given preoperatively in our laboratory. An experiment was devised to see if it could rescue failing flaps. One-hundred Sprague-Dawley rats were divided into a control (N = 25) and five experimental groups (N = 15). All had 10 X 13 cm reverse McFarlane random flaps raised and reinset. The experimental groups underwent hemodilution with either Ringer's lactate or Fluosol at 4, 8, and 12 hours after flap elevation. All were kept in 50% oxygen for 72 hours postoperatively. The flaps and their corresponding necrotic areas were measured on day 7. As to when to institute a therapy, we simultaneously evaluated the use of a microfluorometer as a monitor of flap survival. Analysis of flap survival showed little difference between control and experimental Ringer's lactate or Fluosol groups. Analysis of the microfluorometric data led to the following points. First, as a monitor of flap viability, it is limited by a lack of specificity and sensitivity. Second, comparison of the data from portions of the flap destined to live with those destined to die suggests that it may not be failure of circulatory inflow that leads to flap death.

Dermofluorometric prediction of flap survival.

Techniques to predict flap survival would help the reconstructive surgeon, but while various modalities exist, none is consistently accurate. The standard clinical method of fluorescein visualization by ultraviolet light requires such a high dose that it precludes rapid repetition. Recently, assessment of cutaneous fluorescein with the dermofluorometer has allowed mini-dose fluorescein, quantification, and repetition. The fiberoptic dermofluorometer was tested on experimental and clinical flaps. An experiment was devised to determine if the dermofluorometer could accurately predict flap survival. Modified McFarlane flaps were raised in 10 250- to 300-g female Sprague-Dawley rats and divided into 10 1-cm grids. A dermoviability index was calculated for each grid. A reading below 30% correlated with flap necrosis. Our clinical experiences were less predictive.

Use of computer analysis in flap research.

A computer based analysis of survival of experimental rat skin flaps is presented. The two commonly used experimental flaps, the modified McFarlane dorsal skin flap and the ventral skin flap, are compared. The analysis of the data showed that although the McFarlane flap is random, and the ventral flap based on one epigastric vascular bundle is both axial and random, there was no statistically significant difference in the percent of survival of these flaps. The advantages of the computer based method are discussed.

Fluorocarbon enhancement of skin flap survival in rats.

Fluorocarbons exhibit two unique properties: oxygen saturation in direct proportion to the percent administered and low viscosity which improves microcirculation. These properties were investigated in improving survival in random skin flaps in rats. Modified McFarlane flaps were raised in 30 Sprague-Dawley rats and divided into three equal groups. Group 1 rats served as controls, group 2 rats were hemodiluted with Ringer's lactate, and group 3 rats were hemodiluted with Fluosol-DA (20%). All groups were kept in a high (80%) oxygen environment for 48 hours. Areas of necrosis were measured using a computer system. Necrosis in control flaps averaged 14.96 percent; in flaps hemodiluted with Ringer's lactate, 10.12 percent; in flaps hemodiluted with Fluosol, 4.76 percent. These differences were statistically significant. We conclude that fluorocarbons significantly enhance flap survival in rats.

Infected Meme implants: salvage reconstruction with latissimus dorsi myocutaneous flaps and silicone implants.

Polyurethane-coated breast implants are used more frequently in recent years both in augmentation and reconstruction. Postoperative infection may lead to serious complications with formation of foreign body granulomas. A case is presented with such a complication that required multiple operations and wide excision of reconstructed breasts necessitating major myocutaneous flaps to salvage the breasts.