Evaluation of a bi-layer wound dressing for burn care I. Cooling and wound healing properties

Severe burns remain a significant cause of morbidity and mortality despite the availability of numerous therapies. We assessed the wound healing and skin-cooling properties of a DRDC hydrogel/polyurethane wound dressing using different pre-clinical models. Our results show that 85% of partial-thickness, non-contaminated porcine wounds treated with our dressing healed within 6 days. In contrast, 85% of the wounds treated with commercial dressings healed within 8 days. Application of a moist DRDC dressing (to simulate a condition of exudate absorption) on a scald burn covering 25% of the dorsal area in rats reduced skin temperature by 1.70 +/- 0.14 degrees C for 5 min, the skin temperature being comparable to that of control burned rats after 20 min. The application of a moist DRDC dressing did not induce significant differences in body temperatures compared with that of burned animals without dressing coverage throughout the 90-min experiment. While no change in body temperatures were observed when standard dressings (i.e., not pre-moistened) were applied, skin temperature increased gradually. These data show that our dressing is effective in promoting faster healing of the treated wound; and providing a transient, but beneficial cooling effect to the skin contact-site, without the adverse effect of inducing whole-body hypothermia.     

Novel fabrication of antibiotic containing multifunctional silk fibroin injectable hydrogel dressing to enhance bactericidal action and wound healing efficiency on burn wound: In vitro and in vivo evaluations

The development of biologically active multifunctional hydrogel wound dressings can assist effectively to wound regeneration and also has influenced multiple functions on wound injury. Herein, we designed a carbon‐based composited injectable silk fibroin hydrogel as multifunctional wound dressing to provide effective anti‐bacterial, cell compatibility and in vivo wound closure actions. Importantly, the fabricated injectable hydrogel exhibit sustained drug delivery properties, anti‐oxidant and self‐healing abilities, which confirm that composition of hydrogel is highly beneficial to tissue adhesions and burn wound regeneration ability. Frequently, designed injectable hydrogel can be injected into deep and irregular burn wound sites and would provide rapid self‐healing and protection from infection environment with thoroughly filled wound area. Meanwhile, incorporated carbon nanofillers improve injectable hydrogel strength and also offer high fluid uptake to hydrogel when applied on the wound sites. In vitro MTT cytotoxicity assay on human fibroblast cell lines establish outstanding cytocompatibility of the injectable hydrogel and also have capability to support cell growth and proliferations. In vivo burn wound animal model results demonstrate that the hydrogel dressings predominantly influenced enhanced wound contraction and also promoted greater collagen deposition, granulation tissue thickness and vascularization. This investigation''s outcome could open a new pathway to fabricate multifunctional biopolymeric hydrogel for quicker burn wound therapy and effectively prevents microenvironment bacterial infections.     

结肠靶向吲哚美辛前药的体内外释药特性

目的 观察酶解型吲哚美辛-直链淀粉酯系列(IDM-Am-1～6)的体内外释药特性.方法 IDM-Am-1～6体外胃肠道模拟释药(胃液4 h,pH 1.2;小肠液6 h,1%猪胰酶,pH 6.8;结肠内容36 h,pH7.2),紫外分光光度计检测释放度;SD大鼠按IDM 3 mg/kg分别予IDM(原药组)与IDM-Am-3(前药组)灌胃后,于不同时间点同时取门静脉与外周血,高效液相色谱法检测血药浓度,房室法计算药动学参数.结果 IDM-Am-3在模拟胃4 h、小肠6 h、结肠36 h释药率分别为1.3%、9.3%、95.3%;前药组较原药组吸收明显滞后,门静脉血T_(max)(11.35±2.45)h、MRT(22.27±0.52)h及t_(1/2)(16.74±4.04)h显著延长,C_(max)(9.69±2.40)mg/L及AUC_(0-t)(236.7±13.1)mg/L×h明显降低,外周血AUC_(0-t)(142.8±5.9)mg/L×h较其自身门静脉血低(P<0.01).结论 IDM-Am-3有结肠靶向性能,具有门静脉缓释药动学特点.     

In vivo study of the efficacy of bupivacaine-eluting novel soy protein wound dressings in a rat burn model

Dealing with wound related pain is an integral part of treatment. Systemic administration of analgesic and anesthetic agents is a common solution for providing pain relief to patients but comes at a risk of severe side effects as well as addiction. To overcome these issues, research efforts were madeto provide a platform for local controlled release of pain killers. We have developed a bilayer soy protein-based wound dressing for the controlled local release of bupivacaine to the wound site. The combination of a dense and a porous layer provides a platform for cell growth and proliferation as well as physical protection to the wound site. The current study focuses on the in vitro bupivacaine release profile from the dressing and the corresponding in vivo results of pain levels in a second-degree burn model on rats. The Rat Grimace Scale method and the Von Frey filaments method were used to quantify both, spontaneous pain and mechanically induced pain. A high burst release of 61.8 ± 1.9% of the loaded drug was obtained during the initial hour, followed by a slower release rate during the following day. The animal trials show that the RGS scores of the bupivacaine-treated group were significantly lower than these of the untreated group, proving a decrease of 51–68% in pain levels during days 1–3 after burn. Hence, successful pain reduction of spontaneous pain as well as mechanically induced pain, for at least three days after burn was achieved. It is concluded that our novel bupivacaine eluting soy protein wound dressings are a promising new concept in the field of local controlled drug release for pain management.     

In vitro and in vivo investigation of a novel amniotic‐based chitosan dressing for wound healing

It is more than a decade that amniotic membrane has been used as a wound dressing because of its anti‐inflammatory, anti‐microbial, anti‐fibrotic, anti‐scarring properties, as well as its pain relieving and epithelialization promoting features. However, amniotic membrane had limited applications because it needs to suture in surgery, is highly fragile, firmly adhere to the wound and may cause bleeding and pain when changing the bandage. This study investigated the possibility of development of a novel amniotic‐based chitosan gel dressing as a potential wound repair substrate with marked efficacy. In this experiment, amniotic gel prepared based on chitosan/PVP gel containing human amniotic membrane extract (AME‐Gel) was investigated in terms of wound‐healing efficacy and scar preventive effects in a rat burn model. The levels of re‐epithelialization and dermal regeneration were examined by histological assessment using H&E and Masson's trichrome staining. Also, we clarified the mechanism of healing and cytokine‐releasing activities of AME as well as its effect on epithelization, angiogenesis, and fibroblast growth and migration. Our results revealed that AME‐Gel induces epidermal and dermal regeneration at a shorter time through formation of granulation tissue, enhancement of fibroblast proliferation, and improvement of blood capillary formation concomitant with developing collagen bundles. Therefore, AME‐Gel could be considered a simple and easy to be used as a biological dressing for any type of superficial burn wounds, without any adverse effects.     

In vitro and in vivo testing of a collagen sheet to support keratinocyte growth for use as a burn wound covering

Neonatal Fischer 344 rat keratinocytes were cultured on a collagen sheet to create a 'quasi-skin.' The cells were grown in either control medium or a low-calcium supplemented medium to enhance proliferation. The rate of 3H-thymidine incorporation into DNA was assessed at days 3, 7, 10, and 20 to determine the effectiveness of the medium supplements. The cells grown in supplemented medium did have an elevated rate of incorporation. On days 7 and 14 post culture, the quasi-skin was used to cover full-thickness defects on the dorsum of adult male rats. The covered defects were biopsied 45 and 60 days postoperatively. Light microscopy showed the wounds to be completely re-epithelialized. Barr bodies were present at the wound site, confirming the presence of quasi-skin keratinocytes up to 60 days postoperatively.     

The efficacy and safety of cold atmospheric plasma as a novel therapy for diabetic wound in vitro and in vivo

Cold atmospheric plasma (CAP) is a group of various chemical active species, such as ozone and nitric oxide, generated by working gas. CAP was demonstrated to have an effect on tissue regeneration and wound healing. We conducted this study to evaluate the efficacy and safety of CAP as a novel therapy for diabetic wounds in vitro and in vivo. The plasma consists of ionised helium gas that is produced by a high‐voltage and high‐frequency power supply. Eight‐week‐old male db/db mice and C57BL mice were treated with helium gas (control group), 90s' CAP (low‐dose group), and 180s' CAP (high‐dose group). Mice were treated and observed for 2 weeks. Skin samples from around the wound and blood samples were collected. Our in vitro analysis included scratch wound‐healing assays by using human HaCaT immortalised human epidermal cells. After 14 days of treatment, CAP could obviously promote diabetic wound healing. Wound closure rates were significantly higher in the low‐dose group and high‐dose groups compared with the control group. Meanwhile, compared with the control group, the protein expression of IL‐6, tumour necrosis factor‐α, inducible nitric oxide synthase, and superoxide dismutase in two CAP groups significantly decreased, while the protein expression of vascular endothelial growth factor and transforming growth factor‐β in two CAP groups significantly increased (all P < .05); these data show good agreement with the change in mRNA level (all P < .05). In vitro, scratch wound‐healing assays showed that plasma treatment could effectively ensure healing within 3 minutes of exposure (all P < .05). In addition, no difference was found in histological observations of normal skin and the level of serum alanine transaminase, aspartate aminotransferase, blood urea nitrogen, creatinine, and white blood cells among the CAP groups and control group. CAP treatment for 3 minutes every day improves wound healing in diabetic mice by suppressing inflammation, reducing oxidative stress, and enhancing angiogenesis, involving several proteins signalling, and it is safe for the liver and kidney.     

In vitro assessment of a novel,hypothermically stored amniotic membrane for use in a chronic wound environment

Chronic wounds require extensive healing time and place patients at risk of infection and amputation. Recently, a fresh hypothermically stored amniotic membrane (HSAM) was developed and has subsequently shown promise in its ability to effectively heal chronic wounds. The purpose of this study is to investigate the mechanisms of action that contribute to wound‐healing responses observed with HSAM. A proteomic analysis was conducted on HSAM, measuring 25 growth factors specific to wound healing within the grafts. The rate of release of these cytokines from HSAMs was also measured. To model the effect of these cytokines and their role in wound healing, proliferation and migration assays with human fibroblasts and keratinocytes were conducted, along with tube formation assays measuring angiogenesis using media conditioned from HSAM. Additionally, the cell–matrix interactions between fibroblasts and HSAM were investigated. Conditioned media from HSAM significantly increased both fibroblast and keratinocyte proliferation and migration and induced more robust tube formation in angiogenesis assays. Fibroblasts cultured on HSAMs were found to migrate into and deposit matrix molecules within the HSAM graft. These collective results suggest that HSAM positively affects various critical pathways in chronic wound healing, lending further support to promising qualitative results seen clinically and providing further validation for ongoing clinical trials.     

Monitoring of bactericidal action of laser by in vivo imaging of bioluminescent E. coli in a cutaneous wound infection

The worldwide rise in antibiotic resistance necessitates the development of novel antimicrobial strategies. This study aimed to evaluate the bactericidal action of an 810-nm diode laser in a cutaneous wound infection. An Escherichia coli strain was transformed with a shuttle vector (pRB474) containing firefly luciferase gene from Photinus pyralis resulting in a bioluminescent phenotype. Because firefly luciferase is an enzyme and as such is prone to inactivation at elevated temperature, the first phase has consisted in evaluating in vitro the effect of temperature elevation (30, 40, 50, and 60°C for 2 min) on bacteria bioluminescence. The second phase was performed in vivo. Two full-thickness circular, 14-mm diameter wounds (control and laser-irradiated) were induced on rats. Wound infection was carried out using a suspension (50 μl PBS) containing 5x10⁷ cells of bioluminescent E. coli (10⁹ cells/ml). Thirty minutes later, light irradiation was performed with an 810-nm diode laser (P=10 W, ∅=1.4 cm, fluence: 130, 195, and 260 J/cm²). Temperature was measured within each wound with a noncontact infrared thermometer. Light emission of the bioluminescent bacteria was monitored in vivo by a bioluminescence imaging system before and at 4, 8, 24, and 48 h after laser irradiation. In vitro, bacteria bioluminescence is not affected when temperature is maintained at 50°C for 2 min. In vivo, bioluminescence imaging showed that at 4 h, the viability of E. coli was reduced when compared to the control (CTRL) group (p<0.01). This observation was confirmed at 8 h (p<0.001), at 24 h (p<0.001), and finally at 48 h (p<0.001). Loss of viability of E. coli depends on laser fluence. At 48 h, bioluminescent bacteria were not detected (100% loss of viability) in the wound irradiated at 260 J/cm². For this fluence, the temperature reached 45°C at the end of the irradiation. This study confirms previous observations on the bactericidal effect of diode lasers. Because a progressive desiccation of the superficial dermis is usually observed when using laser irradiation, the hypothesis that laser irradiation dries out the wound making the wound an inhospitable place for bacteria is much more relevant than a direct effect of infrared light on chromophores inside bacteria. This is confirmed by the fact that in this latter case, one would expect an immediate drop in luminescence followed by an increase as the surviving bacteria started to divide and repopulate the wound. However, the exact mechanism deserves further studies. This study points out the advantage of using bioluminescence imaging to evaluate laser for the treatment of acute infections in vivo, nondestructively, and noninvasively.     

Gentamycin delivered from a PDLLA coating of metallic implants: In vivo and in vitro characterisation for local prophylaxis of implant-related osteomyelitis

Locally applied antibiotics support prophylaxis of highly feared implant associated infections. Implant coatings with poly(d,l-lactide) (PDLLA)/gentamicin seem to be a promising approach. Aims of this study were to analyse the release kinetics of gentamicin in vivo, in vitro, to analyse the antibacterial efficacy, the resistance development and its impact on osteoblasts. For the in vitro release experiments titanium implants were coated with PDLLA/gentamicin and the antibiotic release in aqueous solution was analysed at 20 time points (from 10 s to 110 days). For the in vivo experiments PDLLA/gentamicin-coated kirschner wires were implanted in the tibiae of 18 rats. Gentamicin concentration in the bone was analysed at several time points (n = 3 each, 1 h to 7 days). Bactericidal efficacy, bacterial adhesion on the implants and resistance development were tested. AP activity, cell count and CICP expression of osteoblasts were analysed. Gentamicin was released rapidly with an initial burst in aqueous solution and followed by a slow release. Similarly, in vivo gentamicin concentration reached a high peak initially followed by a decrease to a low level. No development of resistance was observed in the investigated setting, the antibacterial efficacy was not affected by the coating process and significantly fewer bacteria were attached to the implant. Osteoblasts were not negatively affected by the gentamicin released from the coating. PDLLA/gentamicin coating resulted in a desired antibiotic peak concentration within the bone. Bacterial adhesion was successfully prevented. No bacterial resistances were developed. This coating seems to be a suitable supplement for prophylaxis of implant-associated infections.     

In vitro evaluation of fibrin mat and Tegaderm wound dressing for the delivery of keratinocytes--implications of their use to treat burns

The effectiveness of fibrin mat and Tegaderm delivery systems to maintain clonogenic keratinocytes in culture were evaluated using in vitro methods. A fibrin mat was found to provide a culture environment that is conducive for the proliferation of keratinocytes and supporting their ability to form colonies of good growth potential in vitro. This confirms that the fibrin mat is a good delivery system for cultured epithelial autograft (CEA). In our unit, fibrin-CEA is limited only for the treatment of severe burns due to the high cost of fibrin glue. However, this substrate is able to maintain the regenerative properties of the CEA which is crucial for the treatment of extensive and full thickness burns. Tegaderm, a cost-effective polyurethane wound dressing is able to support keratinocyte cell growth but at a slower rate and with fewer colonies formed compared to the fibrin system. This suggests that Tegaderm can be an alternative approach of delivering autologous cells, limited to treat chronic wounds and less extensive burns. The use of simple and relatively inexpensive bench techniques can potentially serve as a quality control to check for keratinocytes cultured and delivered to every patient in the clinical setting.     

Clinical and economic burden of wound care in the tropics: a 5‐year institutional population health review

The aim of this study is to evaluate the clinical and economic burden of wound care in the Tropics via a 5‐year institutional population health review. Within our data analysis, wounds are broadly classified into neuro‐ischaemic ulcers (NIUs), venous leg ulcers (VLUs), pressure injuries (PIs), and surgical site infections (SSIs). Between 2013 and 2017, there were a total of 56 583 wound‐related inpatient admissions for 41 461 patients, with a 95.1% increase in wound episodes per 1000 inpatient admissions over this period (142 and 277 wound episodes per 1000 inpatient admissions in 2013 and 2017, respectively). In 2017, the average length of stay for each wound episode was 17.7 days, which was 2.4 times that of an average acute admission at our institution. The average gross charge per wound episode was USD $12 967. Among the 12 218 patients with 16 674 wound episodes in 2017, 71.5% were more than 65 years of age with an average Charlson Comorbidity Index (CCI) of 7.2. Half (51.9%) were moderately or severely frail, while 41.3% had two or more wound‐related admission episodes. In 2017, within our healthcare cluster, the gross healthcare costs for all inpatient wound episodes stand at USD $216 million within hospital care and USD $596 000 within primary care. Most NIU patients (97.2%) had diabetes and they had the most comorbidities (average CCI 8.4) and were the frailest group of patients (44.9% severely frail). The majority of the VLU disease burden was at the specialist outpatient setting, with the average 1‐year VLU recurrence rate at 52.5% and median time between healing and recurrence at 9.5 months. PI patients were the oldest (86.5% more than 65 years‐old), constituted the largest cohort of patients with 3874 patients at an incidence of 64.6 per 1000 admissions in 2017, and have a 1‐year all‐cause mortality rate of 14.3%. For SSI patients, there was a 125% increase of 14.2 SSI wound episodes per 1000 inpatient admissions in 2013 to 32.0 in 2017, and a 413% increase in wound‐related 30‐day re‐admissions, from 40 in 2013 (4.1% of all surgeries) to 205 (8.3% of all surgeries) in 2017. The estimated gross healthcare cost per patient ranges from USD $15789–17 761 across the wound categories. Similar to global data, there is a significant and rising trend in the clinical and economic burden of wound care in Tropics.     

In vitro and in vivo efficacy of a rifampin-loaded silicone catheter for the prevention of CSF shunt infections

Summary Infection of cerebrospinal fluid (CSF) shunts is one of the major complications associated with their use and is usually managed by shunt removal, temporary insertion of an external drainage and implantation of a new shunt system. We have evaluated the efficacy of a rifampin-loaded silicone ventricular catheter to prevent bacterial colonization and infection in vitro and in an animal model.On the basis of an incorporation process a rifampin-loaded catheter was developed which is capable of releasing rifampin in bacteriocidal concentrations for 60 days and more. In a stationary bacterial adherence assay usingS. epidermidis as test strain, the colonization resistance of the device was demonstrated.To assess the capability of the catheter to prevent CSF shunt infections, a rabbit model was developed which allowed the establishment of a reliable and reproducible CSF infection by implantation of silicone catheters into the ventricle and inoculatingS. epidermidis (minimal dose 10⁶ cfu) orS. aureus (minimal dose 10³ cfu). Rifampinloaded catheters (12 animals inoculated with S. epidermidis, 8 animals inoculated with S. aureus) were compared with non-loaded (14 animals inoculated with S. epidermidis, 19 animals inoculated with S. aureus) control catheters, and infection was documented by clinical, microbiological and histological methods.In contrast to the control group, none of the animals with rifampin-loaded catheters showed clinical signs of infection. Furthermore, in none of the materials obtained after sacrifice of the animals (catheter, brain tissue, CSF, blood) could the infecting bacteria be cultured, whereas in materials from animals with the unloaded catheter the infecting strains could always be cultured from the catheter and from surrounding brain tissue. The histological examination of catheter-adjacent tissue supported these findings.We conclude that a rifampin-loaded silicone ventricular catheter is capable of completely preventing bacterial colonization and infection by staphylococci as the main causative organisms in CSF shunt infections and should be further evaluated in clinical trials.     

In vitro and in vivo evaluation of a new dialyzer.

BACKGROUND: Recent dialyzer-related developments have concentrated upon the improvement of performance and biocompatibility. The focus of these developments was predominantly on the membrane itself. A newly developed high-flux dialyzer (FX60) with an advanced Fresenius Polysulfone) membrane (Helixone) overcomes this limitation and has several design-related advantages attributed to the redesign of the individual functional components. For the first time, polypropylene was selected as the material for the dialyzer housing. Both the fibre and the fibre-bundle geometry were refined with the aim of improving overall performance and to reduce dialysate consumption. METHODS: This study aims at investigating the in vitro and in vivo performance of the new FX60 dialyzer with the focus on dialysate flow distribution and dialysate consumption. A new method to analyse dialysate flow distribution, based on local clearances, is suggested. The effect of reducing dialysate flow from 500 to 300 ml/min is investigated in vivo. RESULTS: K(0)A(urea), a common measure to quantify device performance, is found to approach 1000 ml/min for the FX60 with a surface of only 1.4 m(2). Local clearance measurement shows equal performance of the Helixone fibre bundle over the entire cross-section. A dialysate flow reduction by 20% (in vivo) only results in a minor loss in clearance. CONCLUSIONS: The newly developed high-flux dialyzer (FX60) shows a remarkable performance (K(0)A(urea)). The excellent utilization of dialysate could be proven in vivo and is attributed to the superior dialysate flow distribution. A reduction of dialysate flow by 20% could lead to substantial economic savings.     

c-myc amplification and enhancement of sensitivity to cytosine arabinoside: an in vitro and in vivo study on four sublines established from a pulmonary adenocarcinoma

Abstract. Purpose: Meticulous treatment strategies taking tumor heterogeneity into account are considered essential to achieve breakthroughs in current cancer therapy. We analyzed tumor heterogeneity in the primary tumor of a patient with pulmonary adenocarcinoma characterized by a poor prognosis. Methods: Four sublines with different growth characteristics in vitro were established from the tumor using a method for short-term selective cultivation. We examined the differences in morphological, biochemical, and genetic findings of these sublines. Results: Differences in the histological features of the transplanted tumors were seen in the four sublines. The 88-2T and 88-2 tumors revealed a well-differentiated adenocarcinoma; the 88-2F tumor revealed a large cell-like carcinoma resembling the metastatic tumor in the lymph nodes; and the 88-2FA tumor was composed of signet-ring cells. There were differences in oncogenes, with the 88-2F line alone exhibiting 12-fold amplification of c-myc. Sensitivity to cytosine arabinoside (Ara C) was specifically increased in the 88-2F cell line, alone. Conclusions: These sublines demonstrate that human pulmonary adenocarcinoma has various types of heterogeneity within the primary tumor. Furthermore, c-myc amplification may play an important role in altering phenotype and growth characteristics in vitro and in vivo, and for increasing sensitivity to Ara C and the potential of cancer cells to metastasize to lymph nodes. Received: April 9, 2001 / Accepted: November 20, 2001     

In vitro and in vivo evaluation of heparin mediated growth factor release from tissue‐engineered constructs for anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) rupture is a common injury often necessitating surgical treatment with graft reconstruction. Due to limitations associated with current graft options, there is interest in a tissue‐engineered substitute for use in ACL regeneration. While they represent an important step in translation to clinical practice, relatively few in vivo studies have been performed to evaluate tissue‐engineered ACL grafts. In the present study, we immobilized heparin onto electrospun polycaprolactone scaffolds as a means of incorporating basic fibroblast growth factor (bFGF) onto the scaffold. In vitro, we demonstrated that human foreskin fibroblasts (HFFs) cultured on bFGF‐coated scaffolds had significantly greater cell proliferation. In vivo, we implanted electrospun polycaprolactone grafts with and without bFGF into athymic rat knees. We analyzed the regenerated ACL using histological methods up to 16 weeks post‐implantation. Hematoxylin and eosin staining demonstrated infiltration of the grafts with cells, and picrosirius red staining demonstrated aligned collagen fibers. At 16 weeks postop, mechanical testing of the grafts demonstrated that the grafts had approximately 30% the maximum load to failure of the native ACL. However, there were no significant differences observed between the graft groups with or without heparin‐immobilized bFGF. While this study demonstrates the potential of a regenerative medicine approach to treatment of ACL rupture, it also demonstrates that in vitro results do not always predict what will occur in vivo. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:229–236, 2015.     

Mechanical properties of the femur after injection of calcium phosphate cement containing arbekacin sulfate and polylactic acid in a rat model of experimental osteoporosis

 We developed a calcium phosphate cement containing arbekacin sulfate and polylactic acid (CPC95AP) and examined its effects on bone strength by injecting the CPC95AP into the femoral medullary cavity in model rats with osteoporosis. Favorable cortical bone strength was maintained for more than 6 months when CPC95AP was injected into the femoral cavities. This phenomenon was more significant in the weakened femur of osteoporotic rats. The reasons for the increased bone strength are thought to be that the CPC95AP filling increased the geometric moment of inertia and that the binding of CPC95AP with the bones increased Young's modulus. The most important factor is believed to be the increased Young's modulus. The binding of CPC95AP with the bones after filling the femur cavities compensates for the weak extensional strength of CPC95AP, and provides an opportunity to utilize the compressive strength, which is the advantage of CPC95. CPC95AP has antibiotic properties and biocompatibility, and it increases the mechanical strength of the weakened bone; therefore, it is considered useful in bone filling and stiffening. Received: August 3, 2001 / Accepted: December 3, 2001     

In vitro and in vivo evaluation of an oscillometric device for monitoring blood pressure in dialysis patients.

BACKGROUND: Nowadays, an increasing number of dialysis machines lodge a blood pressure (BP) measuring device, whose accuracy has a clear implication for the patients' clinical management. METHODS: An automated oscillometric sphygmomanometer (HD-BPM by Gambro Dasco) used during haemodialysis was submitted to both in vitro and in vivo tests, in order to evaluate some modifications aimed at improving measurement accuracy and consistency. The results were compared with those obtained by another oscillometric monitor (BX-100 by Colin). Three steps of evaluation were followed. First, the maintenance of the overall accuracy requirements prescribed by ANSI/AAMI SP-10 standard was verified. Then, an in vitro validation was carried out by using a test simulator. Finally, during a multi-centre field trial, 392 BP measurement sessions on 53 dialysis patients were collected. Every session consisted of two consecutive intra-dialysis measurements by the oscillometric monitors, each one performed simultaneously to an auscultatory measurement. A comparison with the intra-arterial method was performed as well. RESULTS: When compared with an in vivo data set previously collected, the HD-BPM accuracy complied with required limits. Second, the internal repeatability with respect to the simulator was satisfactory (SD of the differences between device and simulator readings: HD-BPM: systolic = 5.7, diastolic = 4.2; BX-100: systolic = 4.2, diastolic = 5.5 mmHg). Moreover, the comparison between oscillometric and auscultatory methods during in vivo trial gave similar results for the two monitors, even if systolic pressure SD exceeds the limit recommended by ANSI/AAMI SP-10 (mean value of the differences +/- SD: HD-BPM: systolic = 0.5 +/- 9.0, diastolic = 1.5 +/- 6.9; BX-100: systolic = 3.1 +/- 8.2, diastolic = -2.0 +/- 7.6 mmHg). CONCLUSIONS: These data underline the importance of performing accuracy evaluations for BP monitors in the conditions where they normally work, by using well-accepted protocols.