Biomedical subjects
Publications and source records attributed to C W Cummings.
In most cases of posterior epistaxis, the terminal branches of the internal maxillary artery (IMA)--principally the sphenopalatine artery--are believed to be the source of hemorrhage. However, we recently treated three patients in which unexpected or aberrant vascular anatomy resulted in persistent posterior epistaxis.
Explore the source record for details and available documents.
Local hypothermia has been shown to enhance survival of pedicled skin flaps. The effect of prolonged local hypothermia on an important clinical correlate, wound healing, is examined in this study. Skin incisions were made on each flank of nine female pigs, and these incisions were closed primarily. A cooling pad was applied over the incisions on the right side of each animal, achieving an average dermal temperature of 35 degrees C vs 39 degrees C for the control side. Four animals were treated for 72 hours postoperatively; five pigs were treated for 7 days. Wound repair was evaluated by standard histologic techniques at 24 hours, 72 hours, 7 days, and 14 days. Control wounds in all animals demonstrated the normal progression of primary wound repair. We demonstrate that local hypothermia: (1) inhibits wound repair for the duration of its application; (2) is not detrimental to the early 2-week phase of wound healing if applied for 72 hours postoperatively; and (3) may have a beneficial effect by inhibiting inflammation through delay of the late inflammatory phase of wound healing.
Explore the source record for details and available documents.
Random flaps raised in expanded skin demonstrate increased survival lengths when compared with flaps raised on an acute basis. Nutritive blood flow studies performed after skin expansion and elevation show augmented blood flows similar to those seen in conventionally delayed skin flaps. We utilized dermofluorometric analysis to study acute blood flow changes in sequentially, rapidly expanded porcine skin. Four subcutaneous pockets were developed in each of six pigs. The pockets were divided into the following three groups: (1) those with placement of a tissue expander inflated sequentially to 300 mL over four days and then totally deflated on day 6, (2) those with placement of a tissue expander that was not inflated, and (3) those with no tissue expander placed. Measurements were taken immediately before and after tissue expander manipulation in group 1 and daily in groups 2 and 3. Fluorescence was determined at points over and 4, 7, and 10 cm distal to the expander. Blood flow decreased immediately after skin expansion in areas over the tissue expander on days 0 and 1 and returned to baseline levels within 24 hours. Blood flow increased after tissue expander deflation on day 6 but returned to predeflation levels within 24 hours. Capillary blood flow increased over the duration of the study in all three groups. There was no significant difference in blood flow between and among the three groups on day 8, nor was there a significant difference in blood flow between and among sites over and distal to the tissue expander.
Oxygen-free radicals have been implicated as mediators of ischemic damage in a number of tissues, including heart, kidney, small intestine, and skin. Superoxide dismutase, a free radical scavenger, and allopurinol, an inhibitor of xanthine oxidase (a catalyst in the formation of superoxide) have been shown separately to decrease ischemic damage to tissue. Sixty-two male Sprague-Dawley rats (220 to 280 g) were divided into five groups: control, superoxide dismutase only, allopurinol only, high-dose combined allopurinol and superoxide dismutase, and low-dose combined allopurinol and superoxide dismutase. An 18-cm2 ventral island skin flap, based on a single inferior epigastric vessel, was raised and replaced. Blood flow was assessed with a perfusion fluorometer immediately after the flap was replaced, and on postoperative days 1 and 3. Gross necrosis was assessed on postoperative day 7. Gross necrosis was reliably reduced in all groups as compared with the control; however, necrosis in any one experimental group was not significantly different from any other experimental group. Necrosis (expressed as a percentage of the area of the random [distal] half of the flap) was as follows for each group: control, 74%; superoxide dismutase, 43%; allopurinol, 43%; high-dose combined, 48%; low-dose combined, 33%. Blood flow, as represented by the dermofluorescence index, was not changed by any of the treatments. Blood flow was also related to the eventual survival or necrosis for any one portion of tissue. All experimental groups survived with significantly less blood flow than the control.(ABSTRACT TRUNCATED AT 250 WORDS)
Extension of neuromuscular pedicles and direct nerve implants was investigated in ten rabbits. All rabbits underwent facial nerve resection bilaterally. In five rabbits a neuromuscular pedicle, based on the ansa cervicalis nerve, was implanted into the denervated mentalis muscle unilaterally. On the opposite side, reinnervation was attempted using a neuromuscular pedicle with an interposed nerve graft. In the other five rabbits, reinnervation was attempted using a direct nerve implant on one side and a direct nerve implant extended with a nerve graft on the opposite side. Evoked electromyographic muscle tension and histologic studies were used to evaluate reinnervation. Functional neuromuscular units were consistently produced with neuromuscular pedicles, direct nerve implants, and extended direct nerve implants, while extended neuromuscular pedicles failed to produce detectable reinnervation.
Resurfacing of the floor of the mouth and buccal region of the oral cavity and the tonsillar region of the oropharynx may be accomplished with many variations of regional and distant vascularized flaps. Our experiences in the use of 14 lower trapezius myocutaneous island flaps are described with respect to the unique application and suitability of this flap to resurface defects in these areas, as well as the contraindications, both relative and absolute, to the use of this particular method of resurfacing. In addition, the intraoperative technique and attendant problems, as well as postoperative complications, are presented. The overall advantages and disadvantages of this flap as compared with the more traditional pectoralis myocutaneous flap are outlined. It is our belief that because of the distinct qualities of this flap, including extended scope and flap thinness, this method of reconstruction merits consideration in the preoperative planning process.
Magnetic resonance (MR) imaging was used to evaluate myocutaneous flap viability in an animal model. Bilateral myocutaneous panniculus carnosus groin flaps were created in 14 piglets. Eight of the piglets underwent early occlusion of the vascular pedicle to one flap that resulted in flap failure in all cases. Six piglets underwent late occlusion of the vascular pedicle to one flap that resulted in flap survival in all cases. Spin-echo T1- and T2-weighted MR images were obtained from all piglets 2 and 24 hours after occlusion. Additional gadolinium diethylene-triaminepentaacetic acid (DTPA)-enhanced serial T1-weighted images were obtained in four piglets who underwent early occlusion and in four piglets who underwent late occlusion of the pedicle. The T2-weighted images showed increased signal intensity in both occluded and control flaps and thus did not help predict flap viability. Gd-DTPA-enhanced images enabled accurate prediction of flap viability. The images of early-occluded (non-viable) flaps demonstrated no contrast material enhancement, while both the late-occluded (viable) flaps and the control flaps were contrast enhanced. The authors conclude that Gd-DTPA-enhanced MR imaging can help predict myocutaneous flap viability in piglets.
Explore the source record for details and available documents.
A retrospective review of 135 patients surgically treated for obstructive sleep apnea syndrome (OSAS) from 1982 to 1987 was performed to identify perioperative complications and potential risk factors. The incidence of complications was 13% (18/135). Airway problems comprised 77% (14/18) of these complications, resulting in one death. There were three postoperative hemorrhages and one postoperative arrhythmia. Comparison of the complication group versus the noncomplication group showed a statistically significant difference in the minimum oxygen saturation (66% vs. 79%) and apnea index (75 vs. 57) on the pre-operative sleep study and in the amount of narcotic administered intraoperatively. Patients with intubation complications tended to be heavier, whereas patients with extubation complications received significantly more narcotic analgesia intraoperatively. Risk for a perioperative complication was not related to age, type of obstructive symptoms, medical problems, or concurrent septoplasty/tonsillectomy. A protocol for perioperative airway management is presented.
Ancrod is a defibrinogenating enzyme that also stimulates production of prostacyclin and, thereby, acts indirectly as a vasodilator and inhibitor of platelet aggregation. The actions of ancrod have provided the rationale for successful clinical use in the treatment of peripheral vascular disease and venous thrombosis. A porcine panniculus carnosus myocutaneous flap model was utilized to study the effects of ancrod on flap perfusion and viability. Ancrod treatment appeared to increase perfusion at one distal flap site, as measured by dermofluorometry. A small but not statistically significant increase in percent of viable flap surface area was also observed in ancrod-treated piglets.
The sigma-factor composition of Bacillus subtilis RNA polymerase alters during endospore formation. The best-documented change is the appearance of a major sporulation-specific sigma factor (sigma epsilon), which is an RNA polymerase subunit readily detected at 2 to 4 h into the 8-h sporulation process. To determine the nature of the RNA polymerase in differentiating cells after the period of sigma epsilon abundance, we isolated RNA polymerase from cells that were harvested at 6 h after the onset of sporulation. Highly purified fractions of RNA polymerase from these cells contained at least six proteins which cosedimented with core RNA polymerase (beta beta' alpha 2) during glycerol gradient centrifugation. Most of these proteins were in the size range of 20,000 to 29,000 daltons, although one 90,000-dalton protein was also evident. None of the putative RNA polymerase subunits were present in quantities similar to that observed for sigma epsilon during its period of prominence in the cell but instead resembled the minor vegetative-cell sigma factors in abundance. In vitro transcriptions using cloned B. subtilis DNAs as templates revealed at least two novel transcriptional activities in the enzyme that was isolated from cells at 6 h after the onset of sporulation but absent in an RNA polymerase preparation extracted from cells at 4 h after the onset of sporulation. One of these activities was reconstituted by the addition of a 25,000 to 27,000-dalton protein fraction to core RNA polymerase.
The effect of controlled skin expansion in blood flow was investigated using the dermofluorometer. Twenty-eight subcutaneous pockets in seven pigs were divided into three groups. Group 1: subcutaneous pockets with a gradually inflated 200-cc tissue expander over 12 days, then deflated and observed for 6 days. Group 2: subcutaneous pockets with a noninflated 200-cc tissue expander. Group 3: subcutaneous pockets elevated without placement of a tissue expander. Measurements taken 30 to 45 minutes after partial inflation of the tissue expander showed a decrease in blood flow while blood flow was increased 30 to 45 minutes after deflation of the tissue expander. The increase in blood flow, however, was not evident 6 days after the expander in group 1 was deflated.
Multiple surgical approaches to the sella turcica have been described. The sublabial transseptal transsphenoidal approach provides a safe, cosmetically acceptable route to the sella with excellent exposure. Since 1976, we have employed this technique for the surgical treatment of pituitary neoplasms and parasellar tumors. The University of Washington experience with the sublabial transseptal transsphenoidal approach to the sella in a series of 253 patients is reported with respect to the otolaryngological aspects of the surgical technique, results, and complications of the procedure. In addition, a literature review of major studies that used this procedure is included, and the reported results and complications are compared to those of the present study.
Investigations of the effect of dimethyl sulfoxide (DMSO) on skin flap survival have generated mixed results. In addition, to our knowledge, the effect of systemic DMSO on skin flap blood perfusion has not been previously studied. For this study, 48 rats were divided into three groups: (1) a control group, (2) a group injected with DMSO postoperatively only (for seven days), and (3) a preoperatively injected group (for three days preoperatively and seven days postoperatively). The DMSO was given intraperitoneally at a dose of 1.5 g/kg. On each rat, an abdominal island flap (3 X 6 cm) was raised and restored to its original site. Laser Doppler velocimetry and perfusion fluorometry were used to monitor flap perfusion immediately following surgery (day 0) and on postoperative day 3. Flap survival was significantly greater in the DMSO-treated groups when compared with the control group. Significant increases in blood perfusion were noted in the treated flaps on day 3.
The decision to use an end-to-end versus end-to-side anastomosis remains a controversial issue in microvascular surgery, although it is generally accepted that certain clinical situations require skills in both techniques (eg, vessel size discrepancy or the need to preserve donor vessel distal flow). Using rats, this investigation presents a unique free flap model comparing not only arterial end-to-end and end-to-side anastomoses, but venous anastomoses as well. There were 15 animals in each anastomosis group with a greater than 80% flap survival rate in each group. This supports findings of earlier studies that suggested no difference in survival when these two anastomosis types were compared. Equally important was the assessment of dermofluorometry as an immediate postoperative perfusion monitoring device. In this model, fluorometry was not found to be useful for predicting flap viability in an early period after completion of the anastomoses.