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Biomedical subjects

Navin Singh

Publications and source records attributed to Navin Singh.

9 recordsLinked to original sources
PubMed2006

Use of the U-clip for microvascular anastomosis.

Microvascular anastomosis is a demanding skill requiring technical excellence and a thorough knowledge of anatomy and physiology. Every suture placed in a microvascular anastomosis should be considered critical as each has the potential to compromise the delicate reconstruction. As such, any device that can facilitate microvascular suture placement deserves thorough evaluation. The U-clip (Coalescent Surgical, Sunnyvale, CA) is such a device in that it eliminates the often time consuming process of tying knots. We evaluated use of the U-clip in microvascular anastomosis of a 1.5 mm artery. We found the U-clip to offer some advantages including ease of use, traditional feel of directed suture placement (as compared to couplers), and elimination of time needed for knot tying. Its shortcomings include size (in diameter, the "pop-off" section of the device appears larger than standard 8-0 suture), the significant force required to "pop-off" the device and difficulty removing the device.

Adult↗
PubMed2005

Human acellular dermal matrix for repair of abdominal wall defects: review of clinical experience and experimental data.

The use of prosthetic mesh for the tension-free repair of incisional hernias has been shown to be more effective than primary suture repair. Unfortunately, prosthetic materials can be a suboptimal choice in a variety of clinical scenarios. In general, prosthetic materials should not be implanted into sites with known contamination or infection because they lack an endogenous vascular network and are thus incapable of clearing bacteria. This is of particular relevance to the repair of recurrent hernias, which are often refractory to repair because of indolent bacterial colonization that weakens the site and retards appropriate healing. Although fascia lata grafts and muscle flaps can be employed for tension-free hernia repairs, they carry the potential for significant donor site morbidity. Recently, a growing number of clinicians have used human acellular dermal matrix as a graft material for the tension-free repair of ventral hernias. This material has been shown to become revascularized in both animal and human subjects. Once repopulated with a vascular network, this graft material is theoretically capable of clearing bacteria, a property not found in prosthetic graft materials. Unlike autologous materials such as fascial grafts and muscle flaps, acellular dermal matrix can be used without subjecting the patient to additional morbidity in the form of donor site complications. This article presents a thorough review of the current literature, describing the properties of human acellular dermal matrix and discussing both animal and human studies of its clinical performance. In addition to the review of previously published clinical experiences, we discuss our own preliminary results with the use of acellular dermal matrix for ventral hernia repair in 46 patients.

Bioprosthesis↗
PubMed2004

Recipient vessel analysis for microvascular reconstruction of the head and neck.

The selection of recipient vessels that are suitable for microvascular anastomosis in the head and neck region is one of many components that is essential for successful free tissue transfer. The purpose of this study was to evaluate a set of factors that are related to the recipient artery and vein and to determine how these factors influence flap survival. A retrospective review of 102 patients over a 5-year consecutive period was completed. Indications for microvascular reconstruction included tumor ablation (n = 76), trauma (n = 13), and chronic wounds or facial paralysis (n = 13). The most frequently used recipient artery and vein included the facial, superficial temporal, superior thyroid, carotid, and jugular. Various factors that were related to the recipient vessels were analyzed and included patient age, recipient artery and vein, diabetes mellitus, tobacco use, the timing of reconstruction, the method of anastomosis, previous radiation therapy, creation of an arteriovenous loop, and use of an interposition vein graft. Successful free tissue transfer was obtained in 97 of 102 flaps (95%). Flap failure was the result of venous thrombosis in 4 and arterial thrombosis in 1. Statistical analysis demonstrated that anastomotic failure was associated with an arteriovenous loop (2 of 5, P = 0.03) and tobacco use (3 of 5, P = 0.03). Flap failure was not related to patient age, choice of recipient vessel, diabetes mellitus, previous irradiation, the method of arterial or venous anastomosis, use of an interposition vein graft, or the timing of reconstruction.

Adolescent↗
PubMed2003

Recalcitrant abdominal wall hernias: long-term superiority of autologous tissue repair.

Secondary repair of recurrent ventral hernia is difficult, and success depends on re-establishing the functional integrity of the abdominal wall. Current techniques used for closure of these defects have documented recurrence rates as high as 54 percent. The authors' 8-year experience utilizing variations of the components separation technique for autologous tissue repair of recalcitrant hernias emphasizes that recurrent or recalcitrant hernias benefit from the creation of a dynamic abdominal wall. A total of 389 patients were retrospectively identified as having abdominal wall defects, and 284 of these patients met the selection criteria. Study patients were grouped according to the type of surgical repair used. The recurrence rate was 20.7 percent over all study groups and was directly related to the extent of repair required. Group 1 patients (wide tissue undermining) had a recurrence rate of only 15 percent, while in group 2 (complete components separation), the recurrence rate was 22 percent. Group 3 patients (interpositional fascia lata graft) had a 29 percent recurrence rate. Time to recurrence was also significantly different across treatment groups, with study group 3 experiencing earlier hernia recurrence. The most frequent postoperative complication was wound infection, which was directly related to the repair performed. The relative odds of recurrence versus the risk factors of age, sex, perioperative steroid use, wound infection, defect size, and the presence of enterocutaneous fistula were studied with a logistic regression analysis. These factors did not possess statistical significance for predicting hernia recurrence. The preoperative presence of mesh was independently significant for hernia recurrence, increasing the relative odds 2.2 times (p = 0.01). Similarly, when other risk factors were controlled for, increasing the complexity of the treatment group, from study group 1 (wide tissue undermining) to study group 3 (interpositional fascia lata graft), also increased the odds of hernia recurrence 1.5-fold per group (p = 0.04). Average inpatient cost was $24,488. The length of inpatient stay ranged from 2 to 172 days (average, 12.8 days). The length of inpatient stay and costs were directly related to the extent of repair required. Using the analysis of variance test for multiple factors, the presence of an enterocutaneous fistula (p = 0.0014) or a postoperative wound infection (p = 0.008) independently increased the length of inpatient stay and hospital costs. A total of 108 successfully repaired patients were contacted by telephone and agreed to participate in a self-reported satisfaction survey. The patients noticed improvements in the appearance of their abdomen, in their postoperative emotional state, and in their ability to lift objects, arise from a chair or a bed, and exercise. These results suggest that recalcitrant hernia defects should be solved, when possible, by reconstructing a dynamic abdominal wall.

Abdominal Muscles↗
PubMed2002

Facial fractures from dog bite injuries.

Dog bites are commonly associated with soft-tissue injury to the face but rarely result in facial fractures. This article reports six new cases of facial fractures associated with dog bites and reviews additional cases reported in the literature. The demographics of the patients attacked, the location of facial fractures, and the characteristics of associated soft-tissue injuries or complications developing from the dog bite are described. With six new cases and 10 from the literature, this article reviewed a total of 16 cases involving 27 facial fractures. Eighty-seven percent of the cases involved children less than 16 years of age. The periorbital or nasal bones were involved in 69 percent of the cases. Lacerations were the most frequently associated soft-tissue injury. Additional injuries included facial nerve damage, lacrimal duct damage requiring stenting and reconstruction, ptosis from levator transection, and blood loss requiring transfusion. Although facial fractures are not commonly considered to be associated with dog bite injuries, the index of suspicion for a fracture should be raised when the injury occurs in a child, particularly when injury occurs near the orbit, nose, and cheek.

Animals↗
PubMed2002

Contour abnormalities of the abdomen after breast reconstruction with abdominal flaps: the role of muscle preservation.

The purpose of the present study was to determine whether contour abnormalities of the abdomen after breast reconstruction with abdominal flaps are related to the harvest of the rectus abdominis muscle. Abdominal contour was analyzed in 155 women who had breast reconstruction with abdominal flaps; 108 women had free transverse rectus abdominis muscle (TRAM) flaps, 37 had pedicled TRAM flaps, and 10 had deep inferior epigastric perforator (DIEP) flaps. The reconstruction was unilateral in 110 women and bilateral in 45 women. Three methods of muscle-sparing were used; they are classified as preservation of the lateral muscle, preservation of the medial and lateral muscle, or preservation of the entire muscle. One of these three methods of muscle-sparing was used in 91 women (59 percent) and no muscle-sparing was used in 64 women (41 percent). Postoperative contour abnormalities occurred in 15 woman and included epigastric fullness in five, upper bulge in three, and lower bulge in 10. One woman experienced two abnormalities, one woman experienced three, and no woman developed a hernia. Of these abnormalities, 11 occurred after the free TRAM flap, seven after the pedicled TRAM flap, and none after the DIEP flap. Bilateral reconstruction resulted in 11 abnormalities in nine women, and unilateral reconstruction resulted in seven abnormalities in six women. chi2 analysis of the free and pedicled TRAM flaps demonstrates that muscle-sparing explains the observed differences in upper bulge and upper fullness (p = 0.02), with a trend toward significance for lower bulge (p = 0.06). chi2 analysis of the free TRAM and DIEP flaps does not explain the observed difference in abnormal abdominal contour. Analysis of muscle-sparing and non-muscle-sparing methods demonstrates that the observed difference between the techniques is only explained for a lower bulge after the bilateral free TRAM flap (p = 0.04).

Abdomen↗