Resistance to adhesion formation: a comparative study of treated and untreated mesh products placed in the abdominal cavity.

BACKGROUND: New materials have been devised to prevent postoperative adhesions when placing a prosthesis in contact with abdominal contents. METHODS: Eighty rats underwent laparotomy and denudation of the serosa of the cecum and peritoneal covering of the abdominal wall. Five treated mesh products (Parietex Composite, Parietene Composite, Bard Composix E/X, Sepramesh, and Gore-Tex Dual Mesh) and one untreated mesh product (untreated Parietene) were randomly placed between the cecum and abdominal wall. A group without mesh was used as control. The animals were sacrificed at 21 days following surgery and analyzed for the presence of adhesions. RESULTS: The incidence of adhesion formation, mean adhesion area, maximum adhesion length, and strength of adhesion separation were similar between Parietex Composite, Parietene Composite, and Bard Composix E/X, and they were significantly less than with Sepramesh, untreated Parietene, and the control group. Gore-Tex Dual Mesh resulted in less adhesions, adhesion area, mean strength of separation, and work of separation than the untreated Parietene group and the control group. Sepramesh resulted in less strength and work of separation compared to the control group. CONCLUSIONS: The incidence of adhesions and work and strength of adhesion separation are reduced when using a treated mesh, compared to the untreated mesh and the control group without mesh. Parietex Composite, Parietene Composite, Bard Composix E/X, and Gore-Tex Dual Mesh were superior to Sepramesh, untreated Parietene, and the control group in the prevention of adhesion formation.

Fibrin sealant: a novel method of fixation for an implantable ultrasonic microDoppler probe.

While free tissue transfer affords the reconstructive microvascular surgeon the ability to provide coverage for complex wounds, the postoperative monitoring of these flaps continues to evolve. The most recent advance has been the development of an implantable microDoppler probe to provide an early warning signal for vascular obstruction. The current system relies on the use of a silicone cuff to secure a 1-mm probe to the outflow vein. The release force to remove the probe from the cuff is reported to be 1/10 of a pound (45 g). A disadvantage of this system is the need for a circumferential, relatively inelastic device around the vein. Should the cuff be too tightly secured to the vein, the potential for outflow obstruction exists. Moreover, if the probe is not well-approximated to the vein, no signal is produced. Finally, the fact that a foreign body remains in the wound after completion of the monitoring period remains a concern. The authors have investigated a new method to adhere the probe, using a commercially available fibrin sealant. The use of this biocompatible substance has the potential to obviate the need for the current method of fixation, and the associated concerns.

Static magnetic fields for treatment of fibromyalgia: a randomized controlled trial.

OBJECTIVE: To test effectiveness of static magnetic fields of two different configurations, produced by magnetic sleep pads, as adjunctive therapies in decreasing patient pain perception and improving functional status in individuals with fibromyalgia. DESIGN: Randomized, placebo-controlled, 6-month trial conducted from November 1997 through December 1998. SETTING AND SUBJECTS: Adults who met the 1990 American College of Rheumatology criteria for fibromyalgia were recruited through clinical referral and media announcements and evaluated at a university-based clinic. INTERVENTIONS: Subjects in Functional Pad A group used a pad for 6 months that provided whole-body exposure to a low, uniform static magnetic field of negative polarity. Subjects in the Functional Pad B group used a pad for 6 months that exposed them to a low static magnetic field that varied spatially and in polarity. Subjects in two Sham groups used pads that were identical in appearance and texture to the functional pads but contained inactive magnets; these groups were combined for analysis. Subjects in the Usual Care group continued with their established treatment regimens. OUTCOME MEASURES: Primary outcomes were the change scores at 6 months in the following measures: functional status (Fibromyalgia Impact Questionnaire), pain intensity ratings, tender point count, and a tender point pain intensity score. RESULTS: There was a significant difference among groups in pain intensity ratings (p = 0.03), with Functional Pad A group showing the greatest reduction from baseline at 6 months. All four groups showed a decline in number of tender points, but differences among the groups were not significant (p = 0.72). The functional pad groups showed the largest decline in total tender point pain intensity, but overall differences were not significant (p = 0.25). Improvement in functional status was greatest in the functional pad groups, but differences among groups were not significant (p = 0.23). CONCLUSIONS: Although the functional pad groups showed improvements in functional status, pain intensity level, tender point count, and tender point intensity after 6 months of treatment, with the exception of pain intensity level these improvements did not differ significantly from changes in the Sham group or in the Usual Care group.

Use of binaural beat tapes for treatment of anxiety: a pilot study of tape preference and outcomes.

CONTEXT: Recent studies and anecdotal reports suggest that binaural auditory beats can affect mood, performance on vigilance tasks, and anxiety. OBJECTIVE: To determine whether mildly anxious people would report decreased anxiety after listening daily for 1 month to tapes imbedded with tones that create binaural beats, and whether they would show a definite tape preference among 3 tapes. DESIGN: A 1-group pre-posttest pilot study. SETTING: Patients' homes. PARTICIPANTS: A volunteer sample of 15 mildly anxious patients seen in the Clinique Psyché, Montreal, Quebec. INTERVENTION: Participants were asked to listen at least 5 times weekly for 4 weeks to 1 or more of 3 music tapes containing tones that produce binaural beats in the electroencephalogram delta/theta frequency range. Participants also were asked to record tape usage, tape preference, and anxiety ratings in a journal before and after listening to the tape or tapes. MAIN OUTCOME MEASURES: Anxiety ratings before and after tape listening, pre- and post-study State-Trait Anxiety Inventory scores, and tape preferences documented in daily journals. RESULTS: Listening to the binaural beat tapes resulted in a significant reduction in the anxiety score reported daily in patients' diaries. The number of times participants listened to the tapes in 4 weeks ranged from 10 to 17 (an average of 1.4 to 2.4 times per week) for approximately 30 minutes per session. End-of-study tape preferences indicated that slightly more participants preferred tape B, with its pronounced and extended patterns of binaural beats, over tapes A and C. Changes in pre- and posttest listening State-Trait Anxiety Inventory scores trended toward a reduction of anxiety, but these differences were not statistically significant. CONCLUSIONS: Listening to binaural beat tapes in the delta/theta electroencephalogram range may be beneficial in reducing mild anxiety. Future studies should account for music preference among participants and include age as a factor in outcomes, incentives to foster tape listening, and a physiologic measure of anxiety reduction. A controlled trial that includes binaural beat tapes as an adjunctive treatment to conventional therapy for mild anxiety may be warranted.

Modulation of mechanical properties in multiple-component tissue adhesives.

In vitro, ex vivo, and in vivo studies were performed to investigate the effect of mixing upon the mechanical properties of a two-component tissue adhesive. The hypothesis investigated was that a more complete mixing of the two components would yield an increase in the mechanical performance of the adhesive. This in turn would be demonstrated by improved outcomes in models of clinical sealant application. In vitro stereological analysis of tissue adhesive mixed and delivered by several different applicators demonstrated variation in the amount of mixing provided by each type of delivery system. Ex vivo tensile adhesive strength showed that there was a correlation between the amount of mixing and bonding strength; that is, more thorough mixing demonstrated higher adhesive strength. No significant difference was seen, however, between the different applicator types and impact on in vivo dermal incisional closure strength. There was a correlation, though, in amount of mixing and in vivo hemostasis. In a rabbit spleen incision model, a more thoroughly mixed sealant corresponded with a decrease in time to obtain complete hemostasis, as well as less sealant used. The effects of mixing on tissue-adhesive mechanical performance were influenced somewhat by the amount of mixing provided by the applicator. This effect, however, was dependent upon the sealant formulation and the type of in vivo application.

Evaluation of resorbable barriers for preventing surgical adhesions.

OBJECTIVE: To evaluate the ability of collagen film, collagen gel, sodium hyaluronate/carboxymethylcellulose film, and fibrin glue to prevent adhesion formation. DESIGN: Randomized trial using a rat model of a standardized abdominal wound and cecal wound. SETTING: University research laboratory. ANIMAL(S): Sprague-Dawley female rats. INTERVENTION(S): Resorbable barriers or no barrier (controls) were placed between an abdominal wall wound (1 cm x 2 cm) and a similarly sized cecal wound. MAIN OUTCOME MEASURE(S): Adhesion formation between wounds was assessed and quantitated 7 days after surgery. RESULT(S): Without treatment, 34 of 35 untreated rats (97%) developed adhesions. Treatment with collagen gel (3 of 33 rats), collagen film (3 of 10 rats), or sodium hyaluronate/carboxymethylcellulose film (2 of 10 rats) significantly reduced the incidence of adhesion formation. Treatment with fibrin sealant resulted in 9 of 10 animals having adherent wounds 7 days after surgery. CONCLUSION(S): Resorbable barriers of collagen gel, collagen films and sodium hyaluronate/carboxymethylcellulose film were effective in significantly reducing adhesion formation. Fibrin sealant at 7 days had an incidence of adhesion formation similar to that in untreated control animals.

Effectiveness of glycomer 631 monofilament sutures in closing musculoaponeurotic incisions.

The purpose of this study was to quantitate the effect of two monofilament synthetic absorbable sutures as well as a new monofilament synthetic absorbable suture, glycomer 631, in healing musculoaponeurotic incisions in rats. Because these three monofilament synthetic absorbable sutures provided secure closure of laparotomy incisions, their clinical use in laparotomy incisions is recommended.

Influence of latex glove hydration on bacteriophage penetration.

The purpose of this study was to determine whether glove hydration influenced bacteriophage penetration. Using an electronic glove hole-detection device, one brand of latex glove was identified that hydrated rapidly (3.25 min +/- 0.71 min), while another brand was selected that resisted hydration (120 min +/- 0 min). Using a standard bacteriophage penetration model, the amount of bacteriophage penetration in both the rapidly hydrating gloves and the gloves that resisted hydration was extremely small and did not differ significantly from each other.

Influence of Biobrane construction on adherence.

Biobrane (standard adherence) and Biobrane L (light adherence) were compared for their degree of adherence to donor site wounds on rabbits at 1, 4, 7, and 9 days. Biobrane, which has more nylon fabric exposed to the wound surface, had significantly greater adherence levels to the wound at all time periods when compared with Biobrane L, which has less nylon fabric exposed to the wound.

Tissue adhesive wound repair revisited.

The purpose of this experimental study was to compare the effect of a tissue adhesive, N-butyl-2-cyanoacrylate, on the wound's ability to resist infection and gain strength to the effect of percutaneous polypropylene suture. Percutaneous sutures damaged host defenses, inviting the growth of bacteria to a level that was significantly greater than that encountered with the tissue adhesive. Immediately after wound closure, percutaneous sutures provided a more secure closure, as measured by breaking strength, than did tissue adhesives. Seven days later, the breaking strengths of wounds closed by tissue adhesives did not differ significantly from those repaired with percutaneous sutures. Tissue adhesive closure requires less psychomotor skills than suture closure and is accomplished more rapidly than suture closure.

Quantitation of force to dislodge endoscopic ligation clips: EndoClip II vs. Ligaclip ERCA.

The mean forces required to dislodge two types of endoscopic ligation clips from both porcine cystic ducts and silicone tubing were quantitated. The two types of endoscopic clips were EndoClip II and Ligaclip ERCA. Following application of the clips, the force required to dislodge the clips in both a perpendicular direction and a longitudinal direction was determined. The mean levels of force required to dislodge the EndoClip II clips in both directions were significantly (p < or = 0.01) greater than those required to dislodge the Ligaclip ERCA clips.

A new hazard of cornstarch, an absorbable dusting powder.

Cornstarch is currently the only powder used in the manufacture of surgical and examination gloves. The purpose of this study was to determine if cornstarch damages local tissue defenses in contaminated wounds. It was found that in contaminated wounds, cornstarch enhanced the growth of bacteria and elicited exaggerated inflammatory responses as measured by wound induration. As a result of this investigation, we do not recommend the use of gloves with cornstarch powders.

Evaluation of new absorbable Lactomer subcuticular staple.

The most recent advance in skin sampling is the Auto Suture SQS -20 disposable stapler. It approximates and everts wound edges, placing one synthetic absorbable pin in the dermis each time the instrument handle is activated. Staple wound closure was accomplished four times faster than sutural closure of the dermis. Wounds with staple pin closure exhibit superior resistance to infection than wounds approximated by dermal sutures. Although sutures provide more immediate wound security, as measured by wound breaking strength, than dermal pins, the breaking strength of wounds subjected to either dermal pins or dermal sutures were not significantly different 14 days after wounding.

New advances in electronic devices for hole detection.

Holes in surgical gloves are considered to be an important source of transmission of pathogens between surgeon and patient. Two new glove hole detectors have been devised to alert the surgeon to the presence of holes. These devices have been evaluated using six powder-free and seven powdered varieties of surgical gloves that were either dry or exposed to hydration. Eight of the 13 surgical gloves hydrated rapidly with water, altering their resistance to the conduction of electricity. Because the Barrier Integrity Monitor¿ only has a hydration monitor, 68 false positives occurred during the evaluation, indicating to the surgeon that he/she should change gloves unnecessarily because the glove had no hole. In contrast, the Surgic Alert Monitor¿ (SAM¿) had a hydration alarm as well as a glove hole detection alarm. During the 104 tests, the SAM¿ device showed no false positives. In the testing of five of the rapidly hydrating types of surgical gloves, the SAM¿ device could not reliably detect holes. On the basis of this study, the SAM¿ device, in conjunction with gloves that resist hydration, appeared to be a reliable hole detection monitor.

Quantitative monitoring of capsular contraction around smooth and textured implants.

The purpose of this study was to assess the efficacy of textured silicone implants in reducing the incidence of capsular contracture. Each of 10 female New Zealand, albino rabbits received 2 saline-filled implants, 1 on either side of the lateral chest wall. The surface of 1 implant was smooth silicone, whereas the other implant's surface was textured silicone. Magnetic resonance imaging (MRI) scans of the implants were performed at 0, 9, 17, 26, 34, and 40 weeks after implantation. Data from the MRI scans were used to calculate the effective surface area of implants at each analysis interval. This technique provided a noninvasive method of monitoring implant contraction as a function of time. Eight rabbits completed the study. Four of 8 smooth implants developed contractures, whereas none of the textured implants developed contracture. For the 4 smooth implants that developed contractures, MRI scans calculated 72 +/- 12% contraction at 17 weeks, but the Baker palpation test detected only mild firmness. From 17 to 40 weeks, the mean percentage of contraction for these implants changed minimally, but their mean Baker score increased from mild to severe (II to IV). Quantitative data from MRI scans were much more predictive of final implant contraction than palpation (Baker test), applanation tonometry, or indentation tonometry. The latter two tests only detected the final stages of severe implant contraction.

Development of independent vessel security after ligation with absorbable sutures or clips.

The external jugular vein and the contralateral carotid artery in each of 59 rabbits were ligated with either sutures or absorbable clips and then divided. After 0, 1, 2, 4, 7, or 14 days following ligation, the suture or clip was removed, and the vessel's resistance to leakage was quantitated. When the absorbable clips were removed from arteries after 1 day, their mean resistance pressure prior to leakage was 171 +/- 46 mm Hg; in contrast, arteries ligated with a suture did not achieve independent security until after 4 days. At 4 days, the mean pressure prior to leakage of arteries with the suture removed was only 88 +/- 49 mm Hg. Similar results were obtained with veins. The difference in vessel security was attributed to the significant increase in the width of the vessel wall compressed when an absorbable clip was utilized compared with a strand of suture.

Early tissue reaction to textured breast implant surfaces.

Capsular contracture around breast implants with smooth surfaces continues to be an unpredictable complication. Some surgeons believe that silicone implants covered with porous polyurethane foam have a lowered potential to contract. These textured implants are not as biocompatible as silicone. Recently, silicone implants with textured surfaces have been introduced with the hope that the incidence of unacceptable implant contracture will be reduced. Using a rat implant model, the tissue reaction to textured implant surfaces was assessed. The implant surfaces evaluated were Silastic II, Siltex, MISTI, Biocell, Silastic MSI, and Même. Disks of each implant material were implanted under the dorsal skin of rats for a period of 28 days. Each implant with its surrounding tissue was excised, processed for histological analysis, and assessed for the tissue's response to the implant with particular emphasis on the formation of a continuous collagen capsule. The results indicated that the magnitude of surface texturing influenced the development of a complete capsule. Implant surfaces with a texture of less than 150 microns in height or depth (Silastic II, Siltex, and MISTI) resulted in the formation of complete capsules. An implant (Biocell) with irregular texturing (200-350 microns) produced an organized capsule over most of its surface with localized interruptions of the capsule at the sites of its deepest cavities. Implant surfaces with texturing that exceeded 350 microns in height or depth (Silastic MSI and Même) resulted in inhibition of the formation of a continuous capsule during this 28-day study.

Damage to tissue defenses by EMLA cream.

EMLA is a new topical agent that safely anesthetizes intact skin. The purpose of this study was to determine if this cream could be safely used for anesthetizing wounds. This investigation evaluated the potential toxicity of EMLA cream in wounds by measuring its effect on host defenses and on the biology of wound repair. In contaminated wounds, EMLA cream elicited an exaggerated inflammatory response that damaged host defenses, inviting the development of infection. As a result of these investigations, we do not recommend the use of EMLA cream in wounds.

Ease of continuous dermal suture removal.

The purpose of this investigation is to identify the synthetic nonabsorbable monofilament suture that requires the lowest forces for removal of continuous dermal sutures. Immediately after wound closure, continuous dermal polypropylene sutures require the lowest suture removal forces. The ease of polypropylene suture removal from continuous dermal skin closure is related to the suture's low surface coefficient of friction.