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Interaction of hydroxyapatite-titanium at elevated temperature in vacuum environment.

In this study, the interaction between hydroxyapatite (HA) and titanium (Ti) at elevated temperature in vacuum environment was investigated. The 80 wt% HA-20 wt% Ti powder mixtures and 90 wt% HA-10 wt% Ti powder mixtures were dry pressed and heat-treated at 1100 degrees C in vacuum environment. HA powders and the commercially pure Ti powders were used as controls. The heat-treated samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscope (SEM) and energy disperse spectra. XRD and SEM indicated densification of metallic Ti specimens during the in-vacuum heat treatment. Heat treatment of HA specimens in vacuum resulted in the loss of hydroxyl groups as well the formation of a secondary beta-tricalcium phosphate phase. Metallic Ti was not observed in the in-vacuum heat-treated HA-Ti specimens. However, alpha-tricalcium phosphate, tetracalcium phosphate and calcium titanium oxide were observed for the in-vacuum heat-treated HA-Ti specimens. It was concluded that the in-vacuum heat-treatment process completely converted the metal-ceramics composites to ceramic composites.

Coated Materials, Biocompatible↗

[Cesarean section for failed vacuum extraction: risk factors and maternal and neonatal outcomes].

OBJECTIVE: To evaluate risk factors associated with failed attempts of vacuum extraction and their outcomes. PATIENTS AND METHODS: All trial vacuum extractions (metal Minicup) from 1992 to 2000 in Besançon University Hospital Center were retrospectively analysed, namely 2447 cases. Univariate and multivariate analyses of failed vacuum extraction risk factors and descriptive analyse of outcomes were performed. RESULTS: The rate of failed vacuum extractions was 3.47% (85/2447). A multivariate analysis showed the following independent risks factors in failed extraction: extraction above pelvic level + 2 (OR = 1.8; CI 95%: 1.1-3), newborn weight (OR = 2.9; CI 95%: 1.8-4.9), parity >2 (OR = 0.08; CI 95%: 0.01-0.6). In case of failed vacuum extraction, newborns had a significantly higher rate of Apgar score <7 at 1 min (P = 0.0002), but not at 5 min. These newborns were most regularly admitted in pediatric care units (P = 0.01). CONCLUSION: The failed trial attempt vacuum extraction rate stays low. These failed instrumental extractions are more common in an extraction above pelvic + 2, a high fetal weight and an arrest during the second stage of labor. There is an increased adverse neonatal outcome. Clinical fetal weight estimation and diagnosis of presentation level in mother pelvis must be performed before vacuum extraction.

Adolescent↗

Evaluation of vacuum-assisted closure in the treatment of poststernotomy mediastinitis.

OBJECTIVE: Poststernotomy mediastinitis, although infrequent, is a potentially life-threatening complication of cardiac surgery that continues to have a significant morbidity and mortality despite aggressive therapy. Vacuum-assisted closure uses controlled suction to provide evacuation of wound fluid, decrease bacterial colonization, stimulate granulation tissue, and reduce the need for dressing changes. METHODS: One hundred two patients from Duke University Hospital, The Durham Veterans Administration Hospital, and referring institutions underwent vacuum-assisted closure treatment. There were 63 men and 39 women, with a mean age of 67. The infection was noticed between postoperative days 8 and 34, at which time the wounds were opened and debrided. RESULTS: Ninety-six of the 102 patients received vacuum-assisted therapy while the remaining 6 underwent daily multiple dressing changes without vacuum-assisted therapy. Fifty-three of the 96 patients required only sternal debridement, followed by wound vacuum therapy and closure by secondary intention, while the remaining 43 had an additional procedure. Of these, 33 patients underwent omental transposition and 10 patients had a pectoralis flap. The length of stay for all patients was 27 +/- 12 days. This was related in part to intravenous antibiotics. Hospital mortality for all patients was 3.7% (4 patients). Two of these patients underwent vascular flap and succumbed to multisystemic organ failure, while the other 2 received only wound vacuum therapy following debridement and succumbed to overwhelming sepsis. CONCLUSION: Vacuum-assisted drainage is an effective therapy for mediastinitis following debridement or before placement of a vascularized tissue flap.

Aged↗

Clinical evaluation of a "hand pump" vacuum delivery device.

OBJECTIVE: To evaluate the clinical performance of a hand-held vacuum delivery system. METHODS: Between December 1999 and September 2000, a prospective audit was undertaken of all vacuum deliveries performed at Derby City General Hospital. RESULTS: In this period, 3296 deliveries occurred, of which 317 (9.6%) were by vacuum. Of these, data were collected on 300 (94.6%), 78 deliveries with the hand-held vacuum and 222 with standard vacuum. There were no differences in the demographic profiles, indication, gestational age at delivery, or birth weights between the two groups (P >.05 in all instances). In all types of delivery, nonrotational and rotational, the hand-held vacuum performed comparably to its contemporaries with no increase in delivery "failures" being noted. There were no differences in the extent or frequency of maternal injuries between the instruments, and other than transient scalp abrasions, there were no significant fetal injuries. CONCLUSION: The hand-held vacuum delivery system is a functionally effective addition to the practitioners' "armory," providing an alternative to the standard metal and silastic cups.

Adult↗

Vacuum extraction: does duration predict scalp injury?

OBJECTIVE: To identify variables that increase the chance of neonatal scalp injury during vacuum extraction. METHODS: We conducted a prospective observational study of 134 vacuum extraction-assisted deliveries at Olive View-UCLA Medical Center in 1995. Data collected included parity, gestational age, duration of first and second stages of labor, indication for operative delivery, station and position of fetal head, duration of vacuum application, number of "pop-offs," neonatal weight, and descriptions of scalp marks or injury. Cranial imaging studies were obtained if clinically indicated. RESULTS: There were 28 infants with scalp trauma, including 17 superficial lacerations, six large caputs, and 12 cephalohematomata; one infant had subgaleal, subdural, and subarachnoid hemorrhages. Logistic regression analysis showed duration of vacuum application to be the best predictor of scalp injury, followed by duration of second stage of labor and paramedian cup placement. Duration of vacuum application ranged from 0.5 to 26 minutes, with a median length of 3 minutes. The proportion of injuries was greater for applications exceeding 10 minutes (6 of 9) than for those 10 minutes or shorter (22 of 121, P < .01). We did not encounter any cases of clinically important scalp injury. CONCLUSIONS: Cosmetic scalp trauma occurred in 21% of our newborns delivered by vacuum extraction and was more common after longer vacuum applications, longer second stages, and paramedian cup placement.

Adolescent↗

[Patient response to and assessment of intracavernous drug injection and vacuum].

One of the various therapeutic options currently used in erectile dysfunction (ED), vacuum is a procedure that should not be ruled out as it can benefit certain types of patient. To understand each patient's response and usage readiness, a vacuum test is routinely performed by the andrology service as part of the diagnostic study. The present study conducted on 200 patients with ED of different etiologies, included the vacuum test and the intracavernous injection of vasoactive drugs. The assessment included the response to each methodology; which of the two systems offered better response; and initial usage readiness to each system. Positive response was 93% in the vacuum test, and 40% in the intracavernous injection. Improved erection was reported by 73% with vacuum and only 13% with the intracavernous injection. With regard to usage readiness 60.5% favoured vacuum and only 14.5% the intracavernous injection. It was apparent that vacuum is a highly effective methodology with very high initial usage readiness, although ultimate use may be limited for different reasons.

Adult↗

[Complications of vacuum extractor deliveries].

OBJECTIVES: To describe maternal and neonatal complications following deliveries assisted by vacuum extraction and to compare outcomes with those obtained after spontaneous vaginal delivery. We wanted to know if vacuum extractor was a risk factor by itself. MATERIALS AND METHODS: We conducted a retrospective study of two years activity involving 4524 deliveries of which 845 (18.7%) were vacuum extractor assisted. We precisely defined maternal and neonatal complications to compare their rates in spontaneous vaginal delivery and vacuum extractor groups. RESULTS: There were 1333 maternal complications and 114 neonatal complications. The adjusted risks of maternal complications were significantly higher in the vacuum extractor group for simple vaginal tears (OR=3.0; p<0.001), the simple perineal tears (OR=1.8; p<0.001) and third degree perineal tears (OR=2.7; p<0.01). For neonatal complications, the difference was significant for cephalhematomas (OR=10; p<0.001) and scalp abrasions (OR=53; p<0.001). No cases of skull fracture or subgaleal subaponeurotic hemorrhage were recorded. CONCLUSION: Our rates of maternal and neonatal complications after vacuum extractor were similar to those described in the literature. We have been able to show that vacuum extraction is itself a risk factor for third degree perineal tears and cephalhematoma. However, these complications are so infrequent that the advantages of this method of extraction argue in favor of wide use in obstetrics.

Birth Injuries↗

Clinical application of vacuum-assisted cardiopulmonary bypass with a pressure relief valve.

OBJECTIVES: Hemodilution induced by cardiopulmonary bypass (CPB) often prevents open heart operations without blood transfusion because of a large CPB-priming volume. A vacuum-assisted venous drainage system appears to overcome this problem and our previous experimental study demonstrated the beneficial effect of a vacuum-assisted CPB with a pressure relief valve. In this study, we clinically applied this novel system, and evaluated its efficacy by comparing it with the results of a conventional siphon-dependent drainage system. METHODS: Sixty patients undergoing open heart operation were divided into Group V (vacuum-assisted system, n=30) and Group S (siphon-dependent system, n=30). The vacuum-assisted system contains a powerful vacuum generator and a pressure relief valve to keep the negative pressure in the reservoir constant when the blood suction is used. RESULTS: The CPB-priming volume was significantly smaller in Group V (V vs. S: 1071+/-88 vs. 1405+/-137 ml; P<0.01), resulting in the lower hemodilution in Group V evidenced by the minimum hemoglobin level (V vs. S: 6.83+/-1.06 vs. 5.78+/-0.79 mg/dl; P<0.01) and blood transfusion rate (V vs. S: 9 vs. 20%; P<0.01). There were no significant differences in the plasma free hemoglobin level and the reduction ratio of plasma haptoglobin between the groups. CONCLUSIONS: These data demonstrate that this vacuum-assisted CPB can provide simplification of the CPB circuit, resulting in a smaller CPB-priming volume and lower hemodilution. This vacuum-assisted CPB may attenuate the negative effect of CPB by minimizing hemodilution and appears to be a useful modification to accomplish no blood-requiring open heart operations.

Blood Transfusion↗

Comparison of protein solution structures refined by molecular dynamics simulation in vacuum, with a generalized Born model, and with explicit water.

The inclusion of explicit solvent water in molecular dynamics refinement of NMR structures ought to provide the most physically meaningful accounting for the effects of solvent on structure, but is computationally expensive. In order to evaluate the validity of commonly used vacuum refinements and of recently developed continuum solvent model methods, we have used three different methods to refine a set of NMR solution structures of a medium sized protein, Escherichia coli glutaredoxin 2, from starting structures calculated using the program DYANA. The three different refinement protocols used molecular dynamics simulated annealing with the program AMBER in vacuum (VAC), including a generalized Born (GB) solvent model, and a full calculation including explicit solvent water (WAT). The structures obtained using the three methods of refinements were very similar, a reflection of their generally well-determined nature. However, the structures refined with the generalized Born model were more similar to those from explicit water refinement than those refined in vacuum. Significant improvement was seen in the percentage of backbone dihedral angles in the most favored regions of phi, psi space and in hydrogen bond pattern for structures refined with the GB and WAT models, compared with the structures refined in vacuum. The explicit water calculation took an average of 200 h of CPU time per structure on an SGI cluster, compared to 15-90 h for the GB calculation (depending on the parameters used) and 2 h for the vacuum calculation. The generalized Born solvent model proved to be an excellent compromise between the vacuum and explicit water refinements, giving results comparable to those of the explicit water calculation. Some improvement for phi and psi angle distribution and hydrogen bond pattern can also be achieved by energy minimizing the vacuum structures with the GB model, which takes a much shorter time than MD simulations with the GB model.

Computer Simulation↗

[MR-guided vacuum assisted breast biopsy].

OBJECTIVE: This prospective study was undertaken to determine the feasibility of MR-guided vacuum assisted breast biopsy with the Vacora-vacuum-biopsy system for histological evaluation of suspicious lesions in MR-mammography. MATERIAL AND METHODS: During 3 months MR-guided vacuum assisted breast biopsy was indicated in 12 patients with suspicious lesions in MR-mammography. RESULTS: MR-guided vacuum assisted breast biopsy with the Vacora-vacuum-biopsy system could be performed in 9 of 12 patients. In 2 patients the lesions could not be identified at the time of the intervention. In one patient the intervention could not be performed due to obesity. Histopathology revealed benign lesions in 8 patients and malignancy in one patient. In one of the cases with benign histology, the biopsy specimen was not representative for the lesion. CONCLUSIONS: MR-guided vacuum assisted breast biopsy with Vacora-vacuum-biopsy is technical feasible can be performed with a low complication rate.

Adult↗

[Vacuum-assisted closure as temporary coverage in the "problem zone hand"].

INTRODUCTION: Vacuum therapy of hand defect problematic due to the interdigital folds and in particular due to the small surface. As a temporary cover in staged procedures, e. g. following excision of tumor-suspicious skin alterations at the hand, and/or at the fingers, the application of vacuum therapy results not only in a sterile, temporary cover of the wound, furthermore it promotes wound conditioning and reduction of the wound area as well as lymph and edema reduction. PATIENTS AND METHODS: A 75 year old female patient presented herself with a skin alteration at the right dorsal ring finger and the tentative diagnosis of a Morbus Bowen like lesion was raised. Due to the unclear histological status, a staged procedure with excision of the tumour and temporary defect coverage by means of vacuum therapy until final histological evaluation was indicated. We accomplished the radical excision of the unclear skin tumour at the proximal phalanx under preservation of the synovial sheath of the tendon. Subsequently, the wound was temporarily closed with vacuum therapy. Histological examination revealed the complete removal of a solar keratosis. Finally, after 7 days of vacuum therapy as a sterile dressing, with obvious reduction of wound area and simultaneous decrease of edema, the defect was finally covered with a reversed cross finger flap from the adjacent middle finger. The donor site was covered with a full thickness skin graft harvested from the right forearm. The further course was without complication after flap dissection and complete healing. DISCUSSION: Vacuum therapy represents a usefull procedure for temporary wound coverage. Especially at hand defects, when nerves, tendons or bones following trauma or staged procedures are exposed, vacuum therapy can be successfully applied utilizing the special surgical "hand glove" technique.

Aged↗

Sonohysterography: is the hysterosalpingographic vacuum cup a valid alternative device for cannulation of the cervical Os?

PURPOSE: To determine whether sonohysterography (SHG) should be performed with Plexiglas hysterosalpingographic vacuum cups instead of standard catheters. MATERIALS AND METHODS: In a prospective setting, 226 women randomly classified into 2 groups underwent SHG. The method used for cervical cannulation was a two-way catheter in the first group (n = 108) and a Plexiglas hysterosalpingographic vacuum cup in the second one (n = 118). Diagnostic reliability, easy applicability for the physician, discomfort for the patients and cost of the instruments were assessed for both devices. RESULTS: 226/226 (100 %) complete sonohysterographic examinations were performed. As regards uterine cavity distension the same diagnostic reliability was reported for vacuum cups and two-way catheters. The standard catheter obscured the cervical canal because of the dilation of the balloon. Both methods were judged as easy to use, and no statistically significant difference was found as far as the time required for cervical cannulation (p > 0.05). A little more discomfort was recorded by women who underwent sonohysterography with standard balloon catheters but a greater interpersonal variability was noticed in this group (SD 3.65 vs. 1.13 in the vacuum cup group). Vacuum cups were by far the most economical devices (unit cost: 16.70 euro vs. catheter unit cost 46.20 euro). CONCLUSION: Vacuum cups allow sonohysterography to be correctly performed. As they are inexpensive, easy to use, better tolerated by the patients and more helpful for visualisation of the lower third of the uterine cavity, vacuum cups should be considered a serious alternative to standard catheters in the performance of SHG.

Adult↗

Obstetric attending physician characteristics and their impact on vacuum and forceps delivery rates: University of California at San Francisco experience from 1977 to 1999.

OBJECTIVE: The objective of our study was to determine the impact of obstetric attending physician characteristics (eg, region of previous residency training, sex, year of graduation from residency) on the rates of vacuum and forceps delivery at our institution. STUDY DESIGN: The analysis was based on 19,897 vaginal deliveries that were performed by 171 attending physicians and 160 resident physicians between 1977 and 1999 at the University of California at San Francisco Medical Center. Z -tests and multivariate logistic regression were performed on a perinatal database that contained standard obstetric variables. RESULTS: Male attending physicians had a higher percentage of forceps deliveries compared with female attending physicians (11.1% vs 6.6%; P <.001); female attending physicians had a higher percentage of vacuum deliveries compared with male attending physicians (9.8% vs 5.1%; P <.001). However, multivariate regression analysis revealed that only the year in which the procedure was performed affected both the forceps and vacuum delivery rates (P <.041). The region of previous residency training of the attending physician affected the vacuum delivery rate (P <.0001) but not the forceps delivery rate (P >.06) in multivariate logistic regression analysis. Factors such as the sex of the obstetric attending physician, the sex of the resident, and the year of graduation from residency for the obstetric attending physician did not have a significant impact on the forceps or vacuum delivery rates (all P >.05). CONCLUSION: Our study is the first to report that the apparent gender differences in forceps and vacuum delivery rates among obstetric attending physicians was due to the year in which the procedure was performed and not due to sex per se. We also found that the region of previous residency training for the obstetric attending physician significantly influenced the vacuum delivery rate.

Delivery, Obstetric↗

Dynamic monitoring of the dust pickup efficiency of vacuum cleaners.

This study evaluated a new method that uses an optical aerosol photometer for dynamically monitoring dust pickup efficiency during vacuuming. In the first stage of this study the new method was compared with built-in dirt sensors installed by vacuum cleaner manufacturers. Through parallel testing it has been shown that the widely available built-in dirt sensors are not sensitive enough to register small (< 53 microm) dust particles. Therefore, only the optical photometer was used in the rest of the experiments of this study to monitor the dust pickup efficiency while the vacuum cleaner was operated with different nozzles on clean and soiled carpet and vinyl sheet flooring. This method also was used to monitor dust pickup efficiency when vacuuming carpets originating from lead-contaminated homes. The dust pickup efficiencies obtained with the optical aerosol photometer have been compared with the surface lead concentrations found during different stages of cleaning. Results indicate that the dust mass concentration registered with the optical aerosol photometer at the nozzle outlet correlates well with the dust mass collected in the vacuum cleaner filter bag and with the surface lead level. Therefore, dynamic dust pickup monitoring can provide valuable information about the efficiency of cleaning when a vacuum cleaner is used. This suggests that a small aerosol photometer similar to a light-scattering smoke detector would be beneficial in vacuum cleaners used for cleaning surfaces contaminated with leaded dust and biological particles (including allergens).

Aerosols↗

Effect of vacuum on moisture absorption and retention by marinated broiler fillets.

Effects of vacuum on moisture retention and quality characteristics of aged chicken breast fillets were evaluated. One hundred twenty-eight broilers (2 replicates of 64 birds each) were manually slaughtered, chilled in ice water, placed in unsealed plastic bags, and then aged overnight at 4 degrees C. Both pectoralis major muscles were harvested from each carcass. Left muscles were marinated for 30 min en vacuo with 20% (vol/wt) of a 10% NaCl (wt/vol) solution containing 4% (wt/vol) commercial food-grade polyphosphate. Right fillets were marinated similarly but without vacuum. Moisture absorption, cooked yield, pH change during marination, and shear values of vacuum-marinated fillets were compared to those on fillets marinated without vacuum. Use of vacuum during marination increased moisture absorption during marination, but after cooking, yields were similar. Nor did vacuum effect pH or shear values. Under the conditions of this study, use of vacuum during marination appeared to offer no significant advantage over marination at atmospheric pressure.

Absorption↗

The role of vacuum extraction in modern obstetrics.

Vacuum extraction can be an effective technique for operative vaginal delivery, and in some circumstances, it may even be a useful aid in abdominal delivery. Specialized equipment is required, but surprisingly little time is necessary to effect delivery in uncomplicated applications. Rigid vacuum extractors are more effective than pliable instruments but are associated with more fetal scalp trauma. Vacuum extraction spares maternal soft tissue trauma compared with forceps but also more often fails to effect delivery. Unfortunately, both failed vacuum extraction and operative success with delivery can be associated with fetal/neonatal morbidity. It may be that vacuum extraction is an easier technique to learn than forceps, but there is indirect evidence that the ease of application may tempt misuse. Clearly, the technique can be misused, and therefore, good judgment and skill of the operator remain as important as they are in any operative procedure. There are some rare circumstances in which the unique properties of the vacuum confer advantages over forceps, but neither these indications nor the advantages are frequent or clear enough to recommend that every obstetric unit have the availability and capability of vacuum extraction instrumentation and expertise.

Female↗

A randomized trial of misoprostol compared with manual vacuum aspiration for incomplete abortion.

OBJECTIVE: To compare the safety, efficacy, and acceptability of misoprostol and manual vacuum aspiration for the treatment of incomplete abortion in a hospital setting in Kampala, Uganda. METHODS: Three hundred seventeen women with clinically diagnosed incomplete first-trimester abortions were randomized to treatment with either manual vacuum aspiration or 600 mug misoprostol orally to complete their abortions. All women received antibiotics posttreatment and were followed up 1-2 weeks later. RESULTS: Regardless of treatment allocation, nearly all women in this study successfully completed their abortions with either oral misoprostol or manual vacuum aspiration (96.3% versus 91.5%, relative risk 1.05, 95% confidence interval 0.98-1.14). Complications were less frequent in those receiving misoprostol than those having manual vacuum aspiration (0.9% versus 9.8%, relative risk 0.1, 95% confidence interval 0.01-0.78). In the 6 hours after treatment, women using misoprostol reported heavier bleeding but lower levels of pain than those treated with manual vacuum aspiration. Rates of acceptability were similarly high among women in the 2 treatment groups, with 94.2% and 94.7% of women reporting that their treatment was satisfactory or very satisfactory in the misoprostol and manual vacuum aspiration groups, respectively. CONCLUSION: For treatment of first-trimester uncomplicated incomplete abortion, both manual vacuum aspiration and 600 microg oral misoprostol are safe, effective, and acceptable treatments. Based on availability of each method and the wishes of individual women, either option may be presented to women for the treatment of incomplete abortion. LEVEL OF EVIDENCE: I.

Abortifacient Agents, Nonsteroidal↗

Bacterial load in relation to vacuum-assisted closure wound therapy: a prospective randomized trial.

Vacuum-assisted closure has become a new technique in the challenging management of contaminated, acute, and chronic wounds. Although promising clinical results have been described, scientific proof to substantiate the mechanism of action of this therapy is scarce. In the present study, we examined whether the positive effect on wound healing found in vacuum-assisted closure-treated wounds could be explained by an effect on the bacterial load. Fifty-four patients who needed open wound management before surgical closure were included in this study. Wounds were randomized to either vacuum-assisted closure therapy (n= 29) or treatment by conventional moist gauze therapy (n= 25). Healing was characterized by development of a clean granulating wound bed ("ready for surgical therapy") and reduction of wound surface area. To quantify bacterial load, biopsies were collected. No significant difference was found in time needed to reach "ready for surgical therapy" comparing both therapies. Wound surface area reduction was significantly larger in vacuum-assisted closure-treated wounds: 3.8 +/- 0.5 percent/day (mean +/- SEM) compared to conventional-treated wounds (1.7 +/- 0.6 percent/day; p < 0.05). The total quantitative bacterial load was generally stable in both therapies. However, nonfermentative gram negative bacilli showed a significant decrease in vacuum-assisted closure-treated wounds (p < 0.05), whereas Staphylococcus aureus showed a significant increase in vacuum-assisted closure-treated wounds (p < 0.05). In conclusion, this study shows a positive effect of vacuum-assisted closure therapy on wound healing, expressed as a significant reduction of wound surface area. However, this could not be explained by a significant quantitative reduction of the bacterial load.

Adult↗