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Biomedical subjects

Navin K Singh

Publications and source records attributed to Navin K Singh.

9 recordsLinked to original sources
PubMed2006

Robotics in plastic and reconstructive surgery: use of a telemanipulator slave robot to perform microvascular anastomoses.

Many methods for microvascular anastomoses exist, including use of magnifying loupes (x 2.5, x 3.5, x 4.5, x 6), but the operating microscope remains the gold standard. The authors present the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, CA) as an alternative method for performing microvascular anastomoses. The da Vinci robot has fully articulating microinstruments with six degrees of freedom, the ability to filter tremor, the capability to perform telesurgery, and the advantage of 3-D visualization. It offers full and dynamic control over the operating camera, allowing variable positioning and the ability to scale down movements. Its drawbacks include initial high cost, lack of haptic feedback, decreased participation of the first assistant, and lack of widespread availability. In this feasibility study, multiple microanastomoses were performed in canine tarsal and superficial femoral vessels.

Anastomosis, Surgical↗
PubMed2006

The effect of liposuction and diet on ghrelin, adiponectin, and leptin levels in obese Zucker rats.

BACKGROUND: The fat-regulating hormones, adiponectin, ghrelin, and leptin, have been studied extensively with the hope that some therapeutic modality might be gleaned from their augmentation or blockade. The authors studied levels of ghrelin, adiponectin, and leptin after liposuction in obese male Zucker rats. In addition, they altered the fat and carbohydrate content of the rats' postoperative diets to determine whether diet affects hormonal levels and/or liposuction outcome. METHODS: Thirty-five male, obese Zucker rats were divided into four experimental groups. Group I (n = 10) was fed a low-fat/low-carbohydrate diet; group II (n = 10) was fed a regular chow diet; and group III (n = 10) was fed a high-fat/high-carbohydrate diet. Five additional rats served as the baseline, unoperated group. The experimental rats underwent subcutaneous liposuction, and for 6 weeks they were then fed their experimental diets starting on day 0. Experimental rats were euthanized on day 42 and blood was sampled for hormonal, triglyceride, and cholesterol levels. RESULTS: Triglyceride levels were significantly higher in the high-fat/high-carbohydrate group compared with the regular chow and low-fat/low-carbohydrate groups, indicating an effect of diet on systemic circulation after liposuction. Ghrelin levels decreased significantly and leptin levels demonstrated an increasing trend after liposuction. Adiponectin levels did not demonstrate any change with alteration in diet or liposuction. CONCLUSIONS: Liposuction may prove to offer patients medically therapeutic benefits through hormonal alterations. After liposuction, diet plays an important role in weight gain.

Adipocytes↗
PubMed2006

Nipple-areola complex sensitivity after primary breast augmentation: a comparison of periareolar and inframammary incision approaches.

BACKGROUND: The body of literature documenting normative breast sensation and postoperative changes in sensation after reduction mammaplasty has grown considerably over the last several years. Despite this, only two studies have ever been published on the subject of postaugmentation mammaplasty sensory outcomes. The purpose of this study was to precisely measure sensory thresholds at the nipple-areola complex in women who have undergone augmentation mammaplasty by either the inframammary or periareolar approach. METHODS: Twenty women underwent primary augmentation mammaplasty by either the periareolar or inframammary approach at an average follow-up of 1.12 years. Sensory testing was performed using the Pressure-Specified Sensory Device by comparing moving and static sensory thresholds at the upper and lower areola and nipple. Nine women served as size-matched, nonoperated controls in the study. RESULTS: Primary augmentation mammaplasty was found to have a statistically significant negative effect on sensory outcomes when nonoperated controls were compared with women who had undergone augmentation mammaplasty via either the periareolar or inframammary approach. No differences in sensory outcomes were found between the two approaches used. Implant volume was found to be highly predictive of sensory outcomes, with an inverse relationship between implant size and the degree of sensitivity within the nipple-areola complex. CONCLUSIONS: Plastic surgeons should feel comfortable counseling patients that augmentation mammaplasty by either the inframammary or periareolar approach results in no discernible differences in sensory outcomes. Furthermore, women who choose very large implants relative to their breast skin envelopes should be warned about potential adverse sensory sequelae within the nipple-areola complex.

Adult↗
PubMed2005

Robotics in microsurgery: use of a surgical robot to perform a free flap in a pig.

We present the concept that a surgical robot may be used to successfully perform a free flap. To study different microsurgical techniques, a porcine free flap model was developed in our laboratory. Dissection of the free flap model and isolation of the vessels were completed under traditional loupe magnification. The da Vinci robot was then used to perform vessel adventitiectomy and microanastomoses. The model was observed for 4 h postoperatively, noting flap color, temperature, capillary refill, and Doppler signal. At the end of this period, the flap was noted to be viable; anastomoses were evaluated and found to be grossly and microscopically patent. Advantages conferred by the da Vinci robot include elimination of tremor, scalable movements, fully articulating instruments with six degrees of spatial freedom, and a dynamic three-dimensional visualization system. Drawbacks include the cost and the absence of true microsurgical instruments.

Anastomosis, Surgical↗
PubMed2005

Internal mammary perforators: a cadaver study.

Microsurgeons currently employ the internal mammary artery and vein as recipient vessels for microvascular reconstruction of the breast with increasing frequency. Recent reports have demonstrated that the perforating branches of the internal mammary artery and vein can also be used as recipient vessels. The purpose of the following cadaver study was to determine the location and diameter of these internal mammary perforators and whether they are suitable as recipient vessels. Ten fresh cadavers were obtained for this project. Using a micrometer under loupe magnification, bilateral measurements were taken of the perforators from the first five interspaces. The largest arterial perforator averaged 1.74 mm in diameter and the largest venous perforator averaged 1.78 mm in diameter. The largest perforators were most commonly found in the second interspace. Based on the results of this study, the internal mammary perforators appear to have suitable diameter for microvascular anastomosis and should be considered.

Aged↗
PubMed2005

Devascularizing complications of free fibula harvest: peronea arteria magna.

The authors present a case report of devascularizing complications following free fibula harvest. A retrospective review of 93 consecutively imaged limbs demonstrated a peronea arteria magna (PAM) prevalence of 5.3 percent in an urban population, which was used to perform a cost-effectiveness analysis for preoperative vascular imaging of the donor limb using magnetic resonance angiography (MRA) and traditional angiography (TA). Donor-site complications of fibula harvest range from 15 to 30 percent, but are rarely limb-threatening. Limb loss is a dreaded complication of congenital PAM, which can be present with a normal vascular exam. Some microsurgery groups advocate using no preoperative imaging of the donor limb; they rely on intraoperative assessment of the vascular anatomy. An aborted harvest due to aberrant anatomy leads to both direct and indirect added costs. The authors believe that MRA imaging of the donor limb, being minimally invasive, is cost-effective and indicated for free fibula transfers. For equivocal results, conversion to more invasive and costly TA may be necessary.

Adult↗
PubMed2003

Abdominal wall reconstruction with the free tensor fascia lata musculofasciocutaneous flap using intraperitoneal gastroepiploic recipient vessels.

The authors report their experience with a method for definitive abdominal wall reconstruction using the free tensor fascia lata musculofasciocutaneous flap anastomosed to the intraperitoneal gastroepiploic vessels. This is a single-stage reconstruction capable of reconstructing reliably a full-thickness defect involving any region of the abdominal wall. The fascial component of the flap reconstructs the abdominal wall with like tissue, and the cutaneous portion of the free tensor fascia lata provides a durable and aesthetically acceptable external cover. The intraperitoneal gastroepiploic artery and vein were the first-choice recipient vessels used in all three patients. These intraperitoneal recipient vessels allow uninterrupted fascial closure, restoring structural integrity to the abdominal wall, and allow the use of free flaps with short vascular pedicles. The authors present a series of three cases of full-thickness upper and lower abdominal wall reconstruction using this method, presenting its advantages compared with other methods.

Abdominal Neoplasms↗