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PubMed1997

Effect of heat sterilization on the torsional properties of rotary nickel-titanium endodontic files.

The purpose of this study was to determine whether heat sterilization adversely effects the torsional properties of rotary nickel-titanium files, making them more prone to fracture under torsional stress. Nine hundred sizes 2 through 10 Profile Series 29.04 taper files were divided into groups of 10 files each and sterilized 0, 1, 5, or 10 times in the steam autoclave, Statim autoclave, or dry heat sterilizer. Then, they were subjected to torsional testing in a Torquemeter Memocouple. Complete data were collected for sizes 2 through 7, but not for sizes 8 through 10 because their torque resistance exceeded the testing limits of the Torquemeter Memocouple. A one-way analysis of variance was used to compare all experimental groups in sizes 2 through 7 with their unsterilized controls (p < 0.05). Fifty-four comparisons were made for torsional strength and 54 for rotational flexibility. Ten significant changes occurred for torsional strength and 10 for rotational flexibility. Eight of 10 changes in torsional strength were increases. Fifty-two of 54 (96.3%) comparisons for torsional strength and 47 of 54 (87%) for rotational flexibility showed a significant increase or no change. Therefore, heat sterilization of rotary nickel-titanium files up to 10 times does not increase the likelihood of instrument fracture.

Analysis of Variance↗
PubMed1997

Influence of gamma-irradiation sterilization and temperature on the fracture toughness of ultra-high-molecular-weight polyethylene.

Surface damage of the tibial plateau components of knee prostheses made from medical grade ultra-high-molecular-weight polyethylene (UHMW-PE) has been attributed to delamination wear caused by a fatigue fracture mechanism. It has been proposed that factors such as component design and method of sterilization contribute to such failure mechanisms. Understanding the fracture behaviour of UHMW-PE is therefore critical in optimizing the in vivo life-span of total joint components. The elastic-plastic fracture toughness parameter J was consequently determined for a commercial UHMW-PE at ambient and body temperatures, before and after gamma-irradiation sterilization in air at a minimum dose of 29 kGy. Both ductile stability theory and experimental data suggest that cracks propagate in a stable manner, although stability is affected by the sterilization process. Sterilization with gamma-irradiation results in a loss in fracture toughness JIc of 50% and a decrease in tearing modulus (Tm) of 30%. This dramatic reduction could result in a 50% decrease in the residual strength of the components, maximum permissible crack size under service loading and service life (assuming flaws such as fusion defects exist). The time required for a crack to grow from its original size to the maximum permissible size could be decreased by 30%, resulting in earlier failure. In terms of the design of joint replacement components the critical factor to envisage is the design stress level, which should be halved to account for the irradiation process. A scanning electron microscope study reveals that the material fails in layers parallel to the fracture surface.

Biocompatible Materials↗
PubMedDate not supplied

Effect of sterilization method on properties of Palacos R acrylic bone cement.

The focus of this work was a delineation of the effect of the method of sterilization (gamma-irradiation versus exposure to ethylene oxide (EtO) gas) of the powder constituents of Palacos R bone cement on the molecular weight, quasi-static tensile and compressive properties and fatigue performance of the fully polymerized material. It was found that the quasi-static properties are not noticeably affected. However, when the powder constituents were gamma-sterilized, both the molecular weight and the fatigue performance of the cement are significantly lower compared to when the constituents are EtO-sterilized. Explanations are offered for these findings, and recommendations are submitted regarding the preferred method of sterilization of bone cement and reporting of studies in which different formulations of cement are compared.

Bone Cements↗
PubMed2004

[A new hysteroscopic method for sterilization: 45 patients].

OBJECTIVES: French study of the feasibility and safety of a new hysteroscopic method for sterilization under local anesthesia. MATERIALS AND METHODS: After information, all candidates for sterilization were invited to choose between the laparoscopic or hysteroscopic methods. Essure performed under local analgesia was used for hysteroscopic sterilization. Operative time, intensity of pain using a visual analog scale and secondary discomfort were recorded. RESULTS: A cohort of 57 women were enrolled in this study and 45 chose hysteroscopy. Two were excluded after discovery of an intrauterine pathology during the hysteroscopic procedure. Placement of a bilateral device was successful in 41 patients (90.3%); under local analgesia only in 29 patients (68.3%). Mean time needed for device placement was 25.6 9 min and hospital stay was 9.8 hours. Pain was scored 56/100 on the visual analog scale. CONCLUSION: Laparoscopy remains the mainstay method used for sterilization but does involve risks. Hysteroscopic device placement seems to be safe, rapid and an effective procedure.

Adult↗
PubMed1996

Instrument sterilization, skin preparation, and wound management.

Recent advances in instrument sterilization include the introduction of gas plasma sterilization and the increased use of glutaraldehyde. Gas plasma sterilization has the advantages of no toxic residue effects, reduced turnover time, and applicability for sterilization of heat- and moisture-sensitive instruments. Chlorhexidine gluconate (4%) appears to be a superior preoperative surgical scrub for both the surgeon and the patient because of its increased antimicrobial efficacy, residual activity, and minimal tissue reactions. There are many new wound dressings and topical medications for treatment of wounds, but the efficacy of most of these preparations has been evaluated only in humans, dogs, and cats. The ideal topical wound preparation and dressing for equine wounds, particularly wounds affecting the distal limb, have not yet been found.

Animals↗
PubMedDate not supplied

Contaminated anterior cruciate ligament grafts: the efficacy of 3 sterilization agents.

PURPOSE: A study was undertaken to determine the incidence of positive cultures resulting from an anterior cruciate ligament (ACL) specimen dropped on the operating room floor and the efficacy of sterilizing the specimen by soaking in 1 of 3 antimicrobial solutions: an antibiotic solution of neomycin and polymyxin B, 10% providone-iodine solution, and standard chlorhexidine gluconate solution. TYPE OF STUDY: Randomized trial. MATERIALS AND METHODS: Fifty ACL specimens removed from patients undergoing total knee arthroplasty were used as the test group. The specimens were longitudinally sectioned into 4 equal pieces. The 4 pieces were dropped on the floor and left for a period of 15 seconds. Cultures were taken from each specimen after immersion in 1 of the 3 sterilization solutions for a period of 90 seconds. One of the 4 specimens was cultured without being exposed to any solution, thereby establishing these specimens as the control group. Cultures of a floor swab were taken at the same time and place that the ACL was dropped. RESULTS: The floor swab cultures were positive in 48 of the 50 specimens (96%). The ACL control group (untreated dropped grafts) had 29 of 50 specimens positive (58%). The grafts soaked in antibiotic solution had 3 of 50 specimens positive (6%). The grafts soaked in providone-iodine solution had 12 of 50 specimens positive (24%). The grafts soaked in chlorhexidine gluconate solution had 1 of 50 specimens positive (in broth only) (2%). CONCLUSION: This study shows that significant contamination occurs when dropping specimens on the floor, as 58% of the dropped grafts had positive cultures. Of the 3 sterilization techniques used, chlorhexidine gluconate seems to be the most efficient with only a single broth culture (2%) found to be positive. The antibiotic solution was second best (6%), although there is no statistically significant difference between these 2 groups. The 10% providone-iodine solution under these test conditions was the least effective of all the 3 sterilization agents with 24% cultures positive after immersion.

Anterior Cruciate Ligament↗
PubMed1991

A simple and effective method of sterilizing Esmarch bandages.

The authors evaluated three methods of sterilizing Esmarch bandages. A commercially available autoclave tape laid along the whole length of the midpoint of the width of the bandage was used to determine sterility. Satisfactory sterility was achieved by rolling the Esmarch loosely, with a standard crepe bandage interposed between layers. Tightly rolled bandages and folded bandages without the crepe bandage interposition could not be reliably sterilized.

Bandages↗
PubMed1990

Sterilization of orthodontic instruments and bands in cassettes.

The purpose of this study was to determine whether orthodontic instruments and bands contaminated with blood or saliva and bacterial spores can be heat sterilized while contained in OMS-ASAPsys instrument and band cassettes. Hinged and nonhinged instruments and bands were contaminated and dried, placed in the cassettes, ultrasonically cleaned, rinsed, and dried. The cassettes were wrapped and then processed through standard steam, chemical vapor, or dry-heat sterilizing cycles. Each instrument and band was then cultured for the presence of live spores. The results showed that the residual spores on the instruments and bands after ultrasonic cleaning and rinsing had indeed been killed in all cases. The three types of sterilization were equally effective. The results indicate that contaminated orthodontic instruments and bands can be sterilized within OMS-ASAPsys cassettes.

Blood↗
PubMed2003

Preparation and characterization of sterile sub-200 nm meso-tetra(4-hydroxylphenyl)porphyrin-loaded nanoparticles for photodynamic therapy.

A photosensitizer, meso-tetra(4-hydroxyphenyl)porphyrin, was incorporated into sub-150 nm nanoparticles using the emulsification-diffusion technique in order to perform sterilization by filtration using 0.22 microm membranes. The three selected polyesters (poly(D,L-lactide-co-glycolide), (50:50 PLGA, 75:25 PLGA) and poly(D,L-lactide (PLA)) for the nanoparticle production were all amorphous in nature and have similar molecular weights but different copolymer molar ratios. The influence of the copolymer molar ratio and the theoretical drug loading was investigated in terms of particle size, drug loading, entrapment efficiency and surface characteristics. With all the polymers used, sub-150 nm nanoparticles were produced with good reproducibility and narrow size distributions irrespective of both the polymer nature and the theoretical drug loading. After purification by cross-flow filtration, the nanoparticle suspensions were sterilized by membrane filtration and freeze-dried in the presence of a lyoprotectant (trehalose). For all types of nanoparticles, complete redispersion in various media could be obtained. All final freeze-dried products were refiltrable on a 0.22 microm membrane and were stable in terms of mean particle size and drug loading over a period up to 6 months. The effective drug loading increased at higher theoretical drug loading, the entrapment efficiency was however decreased. The same trend was observed with the three polyesters. The sterility of the final freeze-dried nanoparticles was confirmed by the results of the sterility testing which showed no bacterial contamination.

Emulsions↗
PubMed1997

Possible implication of sterile connecting device in contamination of pooled platelet concentrates.

Considering the possibility that a pooled random donor platelet concentrate could become contaminated by welding with a sterile connecting device, we undertook a study to determine the influence of pooling on the contamination rate. As a control group, apheresis platelets were examined. Bacteriological testing was done with a sensitive CO2 detecting culture system, the BacT/ Alert. Out of 1105 pooled platelet concentrates prepared by the buffy coat method, 15 (1.4%) were confirmed as contaminated, all with Staphylococcus epidermidis and two with a second bacterial species, i.e. Staphylococcus capitis and Propionibacterium acnes, respectively. Median detection time by the BacT/Alert was 23 h. Twelve pools of five units were contaminated, which is significantly more than the three contaminated pools of four units. On the other hand, the reuse of the welding wafers proved not be a risk factor for contamination. One welded tubing segment of a contaminated platelet concentrate failed the air leakage test, an incident which was 73 times more frequent than with the sterile platelet concentrates. We found five pooled platelet concentrates containing Staphylococci from which no bacteria could be grown from the individual buffy coats that had been pooled. We suggest the contamination here to have occurred after separation of the buffy coat from the whole blood, possibly during the welding process. Finally, none out of 378 apheresis platelet concentrates was contaminated. All our observations highlight the potential risk for contamination when making pooled platelet concentrates with a sterile connecting device. For this type of transfusion product, we advocate bacteriological screening of all units before release. The incubation time for the sterility test should, however, be limited to 36 h, if logistical problems with the availability of platelets are to be avoided.

Automation↗
PubMed2002

Sterilization of enzyme glucose sensors: problems and concepts.

A useful method of enzyme glucose sensor sterilization has not only to ensure the needs of sterility assurance but has also to guarantee the functional stability of the sensors. The action of 2 or 3% alkalinized glutaraldehyde solution, as well as gamma irradiation with a dose of 25 kGy caused changes of the in vitro functionality and polymer material irritations, respectively. After a combined treatment by 0.6% hydrogen peroxide solution acting over 4 days with 7 kGy gamma irradiation only a slight loss of sensitivity must be registered. The combination of a specially designed universal homogeneous ultraviolet irradiation over 300 s with a 3 days lasting treatment by an inclusion compound of hydrogen peroxide with tensides in urea (0.15% effective hydrogen peroxide concentration) did not cause any influence on the glucose sensor function in vitro. With all methods tested here, a Bacillus subtilis spore reduction over 8 log(10) cycles from 10(6) to 10(-2) spores per test object on an average could be proved experimentally. In general, if non-thermal methods must be used it seems to be impossible to guarantee a sterility assurance level of 10(-6) as it is demanded by the pharmacopoeias. Consequently, effective concepts to produce sterile glucose biosensors for medical and biological applications should be based not only on final product treatments but should include germ reducing measures in every manufacturing step.

Biosensing Techniques↗
PubMed1995

Laparoscopic sterilization: American Association of Gynecologic Laparoscopists' 1993 membership survey.

The 1993 membership survey of the American Association of Gynecologic Laparoscopists received 938 responses, or 13% of the membership. The surgeons reported performing 22,966 sterilizations and 36,482 diagnostic procedures. The distribution of sterilization techniques has remained stable since 1985. Complication rates associated with diagnostic procedures remain consistently higher than those with sterilizations. One death was reported from sterilization, none for diagnostic procedures.

Female↗
PubMed1996

A comparison of the cost of local versus general anesthesia for laparoscopic sterilization in an operating room setting.

OBJECTIVE: To compare the charges between laparoscopic sterilization performed under either local or general anesthesia in a traditional operating room setting with anesthesia personnel in attendance. DESIGN: A retrospective review of charges. SETTING: The Regional Medical Center, Memphis, Tennessee. PATIENTS: Sixty-five women undergoing laparoscopic sterilization, 33 under local and 32 under general anesthesia. Interventions. Laparoscopic sterilization. MEASUREMENTS AND MAIN RESULTS: Patient demographics, history of pelvic inflammatory disease, and history of previous surgery were similar for both groups. Operating room and recovery room times were shorter for patients whose procedures were performed under local anesthesia. Flat-rate fee schedules reduced the cost savings for cases performed under local anesthesia to $529 dollars per case, with 76% ($402) of the savings related to anesthetic drugs or equipment. CONCLUSION: Although these savings appear minimal on a per case basis, if 50% of the approximately 210,000 laparoscopic sterilizations performed in the United States each year were performed under local anesthesia, a savings of over $55 million could be achieved (105,000 cases X $529 = $55,545,000). This would result in substantial overall monetary savings to the health care system.

Anesthesia, General↗
PubMed1991

Control of endemic nosocomial legionnaires' disease by using sterile potable water for high risk patients.

In a setting where potable water is contaminated with Legionella pneumophila serogroup 1, we performed two case control studies. The first case control study consisted of 17 cases of nosocomial Legionnaires' disease (LD) and 33 control (the patients who were admitted to the ward where the case was admitted immediately before and after the case) subjects. Cases had a higher mortality rate 65% vs 12% (P less than 0.004); were more likely to have received assisted ventilation (P less than 0.00001); to have nasogastric tubes (P less than 0.0004) and to be receiving corticosteroids or other immunosuppressive therapy (P less than 0.0001). Based on the results of this study, sterile water was used to flush nasogastric tubes and to dilute nasogastric feeds. Only 3 cases of nosocomial LD occurred during the next year compared with 12 the previous year (P less than 0.0001). Nine cases subsequently occurred and formed the basis for the second case-control study. Eighteen control subjects were those patients admitted to the same unit where the case developed LD, immediately before and after the case. The mortality rate for the cases was 89% vs 6% for controls (P less than 0.00003). The only other significant difference was that cases were more likely to be receiving corticosteroids or other immunosuppressive therapy 89% vs 39% (less than 0.01). We hypothesized that microaspiration of contaminated potable water by immunocompromised patients was a risk factor for nosocomial Legionnaires' disease. From 17 March 1989 onwards such patients were given only sterile potable water. Only two cases of nosocomial LD occurred from June 1989 to September 1990 and both occurred on units where the sterile water policy was not in effect. We conclude that aspiration of contaminated potable water is a possible route for acquisition of nosocomial LD in our hospital and that provision of sterile potable water to high risk patients (those who are receiving corticosteroids or other immunosuppressive drugs; organ transplant recipients or hospitalized in an intensive care unit) should be mandatory.

Case-Control Studies↗
PubMedDate not supplied

Effects of sterilization treatments on some properties of alginate solutions and gels.

Aqueous sodium alginate solutions were subjected to various heat sterilization treatments. Sodium alginate powder was also treated by both gamma-irradiation and ethylene oxide sterilization. The effects of these treatments on the viscosities of sodium alginate solutions and both the diameter and strength of the beads formed in 0.1 M CaCl2 solutions were determined quantitatively. The viscosity of sodium alginate solutions and the gel strength of the calcium alginate beads decreased with increasing sterilization temperature while the bead diameters were found to increase. All these effects can be attributable to a reduction in the degree of polymerization of the alginate molecules as a result of the heat treatments. Ethylene oxide and gamma-irradiation treatments caused similar effects. Standard conditions for sterilization are necessary for comparative studies with alginate beads.

Alginates↗
PubMedDate not supplied

Modeling transport processes in sterilization-in-place.

SIP (sterilization-in-place) of equipment using saturated steam is limited by transport processes that restrict the distribution of sterilizing steam. The following are two crucial operations: the removal of air prior to sterilization, and the removal of condensate during the sterilization. Using simple model systems of pipes and tanks, characteristic operating parameters were examined and steady-state models were analyzed. The results were used to evaluate design aspects of SIP, including heat insulation, spacing of steam traps, sloping of lines, steam velocities and consumption, placement of temperature sensors, and scale factors in piping. A more reliable SIP design is achievable by insulating equipment, spacing steam traps to limit condensate buildup, providing an effective air removal operation, and providing reliable, high-quality steam.

Hot Temperature↗
PubMed1999

Quinacrine sterilization: experience among women at high risk for surgery.

A non-surgical method of female sterilization is needed because many women are at high risk of complications with standard surgical methods, especially in developing countries. Also, some women who desire sterilization refuse it for fear of surgery. To meet these special needs, we initiated a trial of quinacrine sterilization (QS), a non-surgical method involving transcervical insertion of 252 mg quinacrine as pellets by a modified IUD inserter. Diclofenac (50 mg) was inserted with the quinacrine pellets. This insertion was repeated a month later and a 150-mg injection of depo medroxyprogesterone was administered at the time of the first insertion. One hundred and thirty-four women of reproductive age entered the trial. Of these, 92 were considered to be at high risk for surgery, 27 had refused surgery, and 15 had had failed surgical sterilization. Mean follow-up was 3.46 years. No pregnancies or serious complications were experienced. The main side-effect was menstrual irregularity, due probably to the depo medroxyprogesterone injection. QS is a suitable option for women at high risk of surgical complications.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Biodegradable PLGA microspheres loaded with ganciclovir for intraocular administration. Encapsulation technique, in vitro release profiles, and sterilization process.

PURPOSE: The purpose of this work was to obtain a sterilized formulation consisting of biodegradable microspheres of poly (DL-lactide-co-glycolide) (PLGA) for intraocular sustained release of ganciclovir. METHODS: Microspheres were prepared using a dispersion of ganciclovir in fluorosilicone oil (FSiO) that was further dispersed in an acetone solution of PLGA [50/50 and inherent viscosity 0.41 dl/g], and emulsified in silicone oil with a surfactant. Once prepared, the formulation was exposed with an effective gamma radiation dose of 2.5 megarads. The release rate data of ganciclovir from the sterilized and nonsterilized batches were compared using the similarity factor (f2). RESULTS: The dispersion of the drug in FSiO contributed to achieving a drug payload of up to 95% of the theoretical in the 300-500 microm microspheres. Ten mg released ganciclovir in vitro at 1.3 microg/h for the first 21 days, but decreased to approximately 0.2 microg/h from day 25 until the end of the release study (42 days). No significant differences in the amounts of encapsulated drug (alpha = 0.05) were observed between the sterilized and nonsterilized microspheres. Furthermore, dissolution profiles of formulations behaved similarly before and after gamma radiation exposure. CONCLUSIONS: The technique of microsphere preparation described resulted in high ganciclovir loading (95%) and prolonged drug release. The ganciclovir formulation behaved similarly before and after the sterilization process.

Antiviral Agents↗