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Biomedical subjects

L S Nichter

Publications and source records attributed to L S Nichter.

At least 19 recordsLinked to original sources
PubMed1992

Restoration of venous outflow by simultaneous creation of an arteriovenous shunt and pedicle flap using a rat model of foot replantation.

Replantation of amputated rat feet utilizing an efferent arteriovenous shunt constructed between the distal posterior tibial artery and the proximal posterior tibial vein, in the absence of all other venous drainage, provides an alternative pathway to the normal venous drainage in a replanted rat foot. However, this substitute venous drainage was insufficient to prevent progressive ischemia and necrosis of some or all of a replanted rat foot. When a cutaneous pedicle flap supplemented the arteriovenous shunt, venous drainage was much improved, tissue hypoxia and edema began to subside on the third day, severe tissue necrosis was prevented, and seven of eight feet replanted by this technique survived. These observations may be useful in replantation in humans when veins in the amputated part are too small to be used or so damaged that they cannot be repaired or reconstructed by a vein graft, but arteries can still provide a means of returning blood from the amputated part. Constructing an alternative pathway to the normal venous drainage pattern may allow severely damaged parts to survive after replantation.

Anastomosis, Surgical↗
PubMed1992

The biomechanical efficacy of an oscillating K-wire driver.

A new oscillating drill, designed for insertional ease and safety, was biomechanically tested using an MTS 812 servohydraulic material testing machine (Instrom). Holding strength and drilling force were compared against a traditional rotary drill using rabbit tibias to approximate the diameter and cortical thickness of human metacarpals. Three differently sized (0.028-, 0.045-, and 0.062-in. diameter) K-wires were evaluated for each drill. Mean peak axial load (drilling force) was significantly different for each wire driver type in each of the three sized K-wires (p < or = 0.01). The oscillating drill used an average of 3 N less force to penetrate either cortex. Mean peak pull-out force (holding strength) was higher for the oscillating drill, but the difference was not significant (p > or = 0.5). This study indicated that the oscillating drill required less force for insertion and had a similar holding strength as the rotary drill. In addition, our drill has been shown to be less damaging to surrounding soft tissues. This new type of drill is likely to be advantageous in the fields of hand, microsurgery, orthopedic, and plastic surgery, where bone fixation is often near vital neurovascular structures.

Animals↗
PubMed1992

Demineralized bone matrix polydioxanone composite as a substitute for bone graft: a comparative study in rats.

Demineralized bone matrix (DBM) has been successfully used as a substitute for bone grafting. Autogenous bone grafts (ABG) may cause donor site morbidity and undergo significant resorption. DBM may overcome these problems but is mechanically unstable when originally placed. We explored using a slowly resorbable template, polydioxanone (PDS), in combination with DBM and compared it to ABG in a rat 9 x 9 mm cranial defect model. After both 1 and 3 months, histologically and biochemically well-formed bone was present in ABG/PDS and DBM/PDS-treated defects, but not in control defects (PDS alone). Mechanical push-out tests using a servohydraulic testing frame were conducted. Maximum load before failure of DBM/PDS increased from 65% at 1 month to 100% of that of intact skull at 3 months. In contrast, ABG/PDS was 50% as strong as DBM/PDS and not significantly stronger than PDS alone. ABG/DBM did not significantly increase in strength from 1 to 3 months. We conclude that DBM/PDS is better than ABG/PDS in treating cranial defects in the rat model, and that an absorbable osteoinductive bone substitute with superior mechanical advantage is possible without the disadvantages of ABG.

Animals↗
PubMed1991

Leech therapy: when once is not enough.

Venous congestion is a constant threat in the survival of free flaps, pedicled flaps, tissue replantations and traumatized tissue. Leech therapy has proved effective in salvaging much of these compromised tissues. To be effective, leeches must be both readily available and hungry, requirements not always easily met. Our investigation seeks to establish a means to return sated leeches to their previous unfed, hungry state for reuse. Sated leeches were purged of their blood meals by placement in 3% hypertonic saline or by gentle finger pressure, then exposed to serotonin 0 microM (control), 10 microM, 30 microM or 90 microM for 20 min. Subsequent rebiting/refeeding was observed and analysed. Leeches bathed in serotonin rebit or reattached at nearly four times the rate of unexposed leeches; 30% vs 8% respectively. Biting, however, is not refeeding. Overall, 41 leeches were treated with serotonin with four (10%) refeeding. Those that refed consumed a significantly smaller blood meal than the initial feeding; 50% +/- 47% SD vs 348% +/- 143% SD of original body weight. None of the control group refed. As a method for routinely reusing leeches, serotonin bathing cannot be recommended. In the immediate postoperative period with the sudden emergence of venous congestion requiring leech therapy, but with an inadequate number available, this 20% [corrected] refeed rate after 10 microM serotonin exposure could potentially determine the success or failure of the flap/replantation until fresh leeches are made available.

Animals↗
PubMed1991

Expanding the limits of composite grafting: a case report of successful nose replantation assisted by hyperbaric oxygen therapy.

A successful nose replantation assisted by hyperbaric oxygen therapy is presented, with a brief discussion of the possible mechanisms and a brief literature review of the use of hyperbaric oxygen in tissue preservation and replantation. Although it is not certain that the hyperbaric oxygenation ensured the survival of the replanted nose in this 2-year-old girl, there was documented change in graft appearance during the initial hyperbaric oxygen treatment. A 1-month, 1-year, and 2-year follow-up is included.

Child, Preschool↗
PubMed1989

Efficacy of debridement and primary closure of contaminated wounds: a comparison of methods.

Proper management of highly contaminated traumatic wounds frequently requires delayed primary closure of healing by secondary intention to prevent subsequent infection. This animal study compares the efficacy of various wound debridement methodologies to prevent infection following primary closure of treated contaminated wounds. Forty-four Sprague-Dawley rats with uniform, paravertebral incisions were studied. Each wound was inoculated with a standard amount of Staphylococcus aureus bacteria and allowed to remain open for two hours. Each wound was treated before wound closure by one of four debridement methods: (1) surgical scrubbing, (2) high-pressure irrigation, (3) ultrasonication, or (4) soaking. The control animals' wounds were closed without debridement. At 7 days, each animal was evaluated for the presence of gross infection and wound induration. Ultrasound, with a 25% incidence of gross infection, compared with irrigation (75%), scrubbing (82%), and soaking (89%) provided significant protection from subsequent abscess formation. The control group uniformly developed infection (100%). The average amount of induration after ultrasonication (1.35 +/- 0.56 cm) was also significantly less than irrigation (2.07 +/- 0.75 cm), scrubbing (1.95 +/- 0.34 cm), and soaking (1.73 +/- 0.22 cm). Our data demonstrate that ultrasonic wound debridement has exciting potential as a new debridement technique for contaminated traumatic wounds.

Animals↗
PubMed1989

An unusual complication of an open-head injury: coccidioidal meningitis.

A case of coccidioidal meningitis following an open-head injury is presented. A 6-year-old boy was ejected from a motor vehicle as it was driven over a cliff, resulting in a severe open-skull fracture with grossly contaminated wounds. The accident occurred in an area in which coccidioidomycosis is endemic, and the causative agent, Coccidioides immitis, is found in high concentration in the soil. In addition to fracture reduction, the child received a course of intrathecal and intravenous amphotericin and achieved a satisfactory clinical response.

Amphotericin B↗
PubMed1989

Intralesional corticosteroid therapy for infantile hemangiomas.

Intralesional corticosteroid injections were performed in 31 hemangiomas in 30 infants aged 1 to 10 months at first injection. One to five injections were given, spaced 6 weeks apart. Lesions were located throughout the head and neck region, except one that was on the buttock. A mixture of betamethasone acetate and triamcinolone acetonide was used. Four lesions (13 percent) virtually disappeared, ten (32 percent) showed greater than 50 percent reduction in volume, ten (32 percent) showed definite but less than 50 percent reduction in volume, and seven (23 percent) showed little or no decrease in size. None showed further growth. All injections were performed without anesthesia, and there were not significant complications. We conclude that intralesional corticosteroid injections are safe and effective in properly selected infants with hemangiomas.

Betamethasone↗
PubMed1988

Cost of treating advanced leg ischemia. Bypass graft vs primary amputation.

We compared the hospital costs of 94 patients undergoing femoropopliteal bypass grafts with those of 53 patients undergoing primary amputation. The total cost of uncomplicated bypass surgery averaged +20,300, compared with +14,000 for uncomplicated below-knee amputation. However, including the cost of prosthesis and rehabilitation, the total cost of primary amputation was +20,400, equivalent to that of the bypass operation. Complications requiring revision of a bypass graft increased hospitalization by 4.5 days with the total cost rising to +28,700; complications that ended with major amputation added 15 hospitalization days and had an average cost of +42,200. In contrast, complicated below-knee amputation cost +40,600 and added 12.5 hospitalization days. There is therefore no cost-benefit in primary amputation when compared with arterial reconstruction, and cost should not be used to deny a patient the opportunity for limb salvage.

Amputation, Surgical↗
PubMed1988

Improving micrograft patency.

To help clarify many of the controversial issues affecting early microvascular graft patency, a series of experiments was performed comparing the relative importance of graft material used alone and in conjunction with antiplatelet agents. Using a rat carotid model employing 1 cm micrografts with 1 mm luminal diameter, this study demonstrated that 1) untreated 1 mm polytetrafluoroethylene (PTFE) and human umbilical vein (HUV) micrografts have unacceptably low patency rates; 2) treatment with the antiplatelet agents indomethacin, ibuprofen, and aspirin significantly improved micrograft patency; 3) differences in patency among the three agents were not significant; and 4) PTFE had higher patency rates than HUV, although this difference did not achieve significance.

Animals↗
PubMed1988

Ultrasonic wound debridement.

Current management of hand injuries includes debridement by abrasive scrubbing with anti-bacterial detergents, surgical excision, or pressure irrigation. A rat model with a contaminated laceration was used to study the efficacy of ultrasonic debridement to diminish bacterial counts and particulate matter in open wounds. Ultrasonic debridement of hand wounds has several advantages over the current methods of wound debridement. These include a technically simple procedure that is effective in the removal of particulate matter and the reduction of bacterial counts (p less than 0.005). In addition there was no blood loss and no detectable damage of viable tissues as evaluated by electron microscopy. This technique may prove to be a significant advance in the early management of hand wounds.

Animals↗
PubMed1988

Computer-assisted burn care.

The use of a computer does not take the thought process out of burn care. Rather, it provides constant user reinforcement while emphasizing key elements of burn care management.

Burns↗
PubMed1988

Bony and soft tissue reconstruction and rehabilitation following traumatic hemipelvectomy, exsanguination and cardiac arrest.

Survival following traumatic hemipelvectomy in the child with subsequent local flap coverage of wounds has been previously described. The use of axial skin flaps and thigh and rectus abdominis musculocutaneous flaps for coverage of hemipelvectomy defects following tumor extirpation has also been noted in the literature. The use of muscle flaps to salvage otherwise nonvital bone and to eradicate osteomyelitis with subsequent wound closure has also been thoroughly demonstrated both clinically and experimentally. The use of musculocutaneous flaps to revascularize otherwise nonviable bone of the pelvis and thus maintain the pelvic girdle integrity, however, has not to our knowledge been previously reported. We recently had an opportunity to treat such a case, which we herein describe.

Amputation, Traumatic↗
PubMed1988

Radionuclide-labeled red blood cell imaging of vascular malformations in children.

Vascular malformations, particularly in the absence of cutaneous changes, can be difficult to distinguish from other soft tissue masses in children. We have used technetium-99m-labeled red blood cell scintigraphy to study 47 lesions in 43 children. Thirty-nine lesions showed increased flow and were, therefore, diagnosed as vascular malformations. Subsequent biopsy of 10 of these lesions confirmed that diagnosis. The other 29 lesions with increased flow were followed for 10 months to 5 years and the clinical course was consistent with vascular malformation in every case. Eight lesions showed no increased flow on technetium scan. One of these subsequently proved to be a hemangioma. The others have turned out not to be vascular malformations. Therefore, in our experience, the technetium-99m-labeled red blood cell scan has had 98% sensitivity and 100% specificity in diagnosing vascular malformations in children.

Adolescent↗
PubMed1988

Efficacy of verapamil in the salvage of failing random skin flaps.

Verapamil is a calcium channel blocker that inhibits mast cell degranulation, platelet aggregation, and neutrophil function and is a potent vasodilator. The efficacy of verapamil (20 mg/kg/day) to salvage a standard failing random skin flap in the rat was studied. In this study verapamil failed to benefit skin flap survival. The results are analyzed and presented.

Animals↗
PubMed1988

Dermabrasion of traumatic tattoos: simple, inexpensive, effective.

In this article we describe the use of an electrosurgical cautery tip scratch pad for the treatment of traumatic (adventitious) tattoos. This inexpensive item is available in most surgical operating rooms. The pad is flexible yet firm and obviates the need for power equipment. Most important, the technique is simple, easy to learn, and highly effective.

Blast Injuries↗