Sterile versus clean technique in postoperative wound care of patients with open surgical wounds: a pilot study.

PURPOSE: This study was completed to determine whether there were differences between sterile versus clean dressing change technique for open surgical wounds in the postoperative period with respect to (1) rate of wound healing and (2) cost of supplies. METHODS: A two-group design was used for this pilot study. Of a sample of 30 patients undergoing elective gastrointestinal operations with wounds healing by secondary intention, 15 were men and 15 were women. Mean age was 40.6 years (SD 13.0 years). Patients were randomly assigned to receive clean or sterile dressings, and the intervention was begun on the first postoperative day and repeated three times a day until discharge from the hospital. Analysis of rate of healing was performed with the Mann-Whitney U test: cost analysis was completed with a t test. FINDINGS: Subjects were studied for 3 to 9 days. Groups were homogeneous of the start of treatment with respect to age, length of operation, wound volume, nutritional status, and perfusion. There was no difference in rate of wound healing between the clean and sterile groups. Mean cost was significantly less for the clean group than for the sterile group. CONCLUSION: These pilot study data show no difference in rate of wound healing with clean versus sterile technique, and clean technique is less expensive. These findings need to be confirmed with a larger sample; type II error cannot be ruled out.

Quantitative assessment of the tissue response to films of hyaluronan derivatives.

The aim of this study was to evaluate the in vivo response following implantation into a rat model of three innovative hyaluronan derivatives for clinical use: HYAFF 7, HYAFF 11 and HYAFF 11p75 (respectively, the 100% ethyl ester, 100% and 75% benzyl esters). The tissue reaction evoked by films of these new biomaterials implanted into the dorsolumbar musculature of rats was assessed quantitatively using a well established technique based upon an image analysis system. The number of inflammatory cells present and the patterns of cell distribution around the implant up to a distance of 642 microns were examined at different time periods after implantation. Since a well-delineated tissue-material interface was needed for this type of investigation, it was not possible to apply image analysis to sections once dissolution of the implanted materials had begun. Films of both the total esters, HYAFF 7 and HYAFF 11, were found to undergo a slow dissolution process and, after a month, films of these materials were still present at the site of implantation. Differences in response to the two materials were observed only during the first two weeks, particularly with respect to neutrophil distribution and total cellularity. HYAFF 7 was found to be more reactive, with higher numbers of neutrophils near the surface of the implant than HYAFF 11. Thereafter, the differences between the two materials were minimal and owing mainly to a faster dissolution of HYAFF 7 films. After 3 and 5 months, considerable degradation of films of both total esters had occurred. Significant quantities of material appeared inside numerous macrophages with an ED1-positive phenotype. Only a very thin layer of fibrous connective tissue, indicative of low reactivity, was found to surround the site of implantation, separating the dissolved material and the phagocytic cells from healthy muscular tissue. ED2-positive macrophages were primarily confined within the lining connective tissue. The partial benzyl ester, HYAFF 11p75, showed a different behaviour. In fact, evidence of film dissolution was already present a week after the implantation. After two weeks, the implanted films were completely dissolved and numerous ED1-positive macrophages phagocytosing the material were observed at the site of implantation. Therefore, in agreement with previous in vitro studies, which showed a greater susceptibility to degradation of hyaluronan derivatives with lower percentage of esterification, HYAFF 11p75 underwent resorption faster than the corresponding total ester.

The economics of advanced biomaterials.

A patient who has previously lost an eye through trauma develops a cataract in his remaining eye. Two types of intraocular lens are available for his treatment, one of modest cost, which is effective in all but a few high-risk patients, the other much more expensive, which gives marginally better results on average, but better performance in those with diabetes or glaucoma. Should the higher-cost lens be used even if there is no direct evidence that it will do better in this patient who does not have these conditions, or is it ethically justified to use the lower-cost lens even though failure would result in the total loss of sight? This case is used as the basis of a discussion on the use of high-cost materials and medical devices.

Quantitative in vivo assessment of the tissue response to dermal sheep collagen in abdominal wall defects.

We quantified the tissue response, tissue organization and patency of biodegradable patches for the repair of abdominal wall defects. We used dermal sheep collagen, cross-linked with hexamethylenediisocyanate in a model. The collagen patches were implanted either untreated or plasma polymerized with tetrafluoroethylene (TFE), to improve the properties of the patch for bowel adhesion and rate of degradation. The implants with surrounding tissue were retrieved after 3 d, 1, 2, 4, 6 and 8 wk, then sectioned and stained specifically for macrophages, neutrophils, T-lymphocytes and endothelium. Only macrophages and neutrophils were observed in the implant and surrounding tissue, with different antigen expression in the macrophages. This was found to be dependent on whether the macrophages were found within the implant or in the surrounding tissue. The neutrophils and macrophages were assessed using image analysis techniques to quantify the tissue responses to treated and untreated collagen, enabling comparison of the respective tissue responses. No significant differences were found between the two forms of this collagen. Infection played a key role in the severity of the tissue response around both types of implants, resulting in large variations in cell counts at each time period. Treating the collagen with TFE did not significantly improve its performance in this application.

Outcome and cost analysis of scheduled versus emergency scleral buckling surgery.

BACKGROUND: Retinal detachments are usually considered to be a surgical emergency. However, there are additional risks and costs for unnecessary emergency surgeries. The purpose of this study is to evaluate whether the conventional wisdom for treating all retinal detachments as emergencies needs to be re-examined. METHODS: Forty-eight patients who had an emergency scleral buckle and 89 patients who had a scheduled procedure were randomly selected from 884 consecutive patients who had a primary scleral buckling procedure during a 4 1/2-year period. The medical records of each patient were used to obtain detailed information related to prognosis. The visual acuity measurements of each patient, taken 6 months after the procedure, were obtained from the records of the ophthalmologist following the patient. Linear regression analysis was used to compare the final visual outcome for patients who had emergency surgery with patients who had scheduled surgery after taking into account patient factors related to prognosis. RESULTS: Patients selected for emergency surgery had better visual prognoses than scheduled patients but had the same risk of systemic complications and the same extent of detachment if the macula was not involved. None of the 18 patients with an attached macula experienced macular involvement while awaiting scheduled surgery. There were no differences between emergency and scheduled patients in ocular or systemic complications, rate of reattachment, rate of decreased visual acuity after surgery, visual outcome adjusted for prognosis, or, since 1985, length of hospital stay. A greater cost was incurred for the patients having emergency surgery due to difference in pay scales for support personnel. CONCLUSIONS: Because the study is not large and the patients were not randomized to treatment, the results are not definitive. However, they suggest that emergency surgery is unnecessary for many patients with a detached retina.

Quantitative assessment of the tissue response to implanted biomaterials.

The tissue response to a small number of polymeric biomaterials was studied using monoclonal antibodies specific for certain inflammatory cell types, to develop a reliable and accurate method for the quantitative evaluation of biocompatibility. The sites of antibody binding were identified using an avidin-biotin staining procedure and the sections evaluated using a computer-aided image analysis system. The staining technique successfully demonstrated both polymorphonuclear leucocytes and macrophages in tissue samples containing polymeric biomaterials. The image analysis system facilitated the measurement of up to 30 cell-related parameters and allowed a large number of cells to be analysed.

Outcome and cost analysis of scheduled versus emergency scleral buckling surgery.

Conventional wisdom holds that a retinal detachment of recent onset should be regarded as a surgical emergency. A delay in surgery may result in an extension of detachment for patients with an attached macula and a worse visual outcome for patients with a detached macula. However, the potential disadvantages of performing surgery on an emergency basis must be weighed against the risks of delaying surgery; disadvantages include a greater frequency of operative complications resulting from fatigue factors among the operating personnel, an increased anesthetic risk due to inadequate time to assess and stabilize coexisting medical problems, and higher hospital costs. In this retrospective study covering 4 1/2 years, we compared the risks, benefits, length of hospitalization, and costs of scleral buckling surgery for retinal detachments performed as an emergency procedure or on the day following admission. After a 15% random selection from 884 consecutive operations, 48 emergency procedures were compared with 89 scheduled procedures. Patients selected for emergency surgery had better visual prognoses than scheduled patients. The potential for risk of systemic complications was not a reason for postponing surgery. None of the 18 patients with an attached macula experienced macular involvement while awaiting scheduled surgery. There were no differences between emergency and scheduled patients in ocular or systemic complications, rate of reattachment, rate of decreased visual acuity following surgery, visual outcome adjusted for prognosis, or, since 1985, length of hospital stay. Cost was greater for patients having emergency surgery, because of a difference in pay scales for support personnel.