Predictors of rehospitalization for symptomatic venous thromboembolism after total hip arthroplasty.

BACKGROUND: Recent studies have shown that symptomatic venous thromboembolism after total hip arthroplasty most commonly develops after the patient is discharged from the hospital. Risk factors associated with these symptomatic thromboembolic events are not well defined. METHODS: Using administrative data from the California Medicare records for 1993 through 1996, we identified 297 patients 65 years of age or older who were rehospitalized for thromboembolism within three months after total hip arthroplasty. We compared demographic, surgical, and medical variables potentially associated with the development of thromboembolism in these patients and 592 unmatched controls. RESULTS: A total of 89.6 percent of patients with thromboembolism and 93.8 percent of control patients were treated with pneumatic compression, warfarin, enoxaparin, or unfractionated heparin, alone or in combination. In addition, 22.2 percent and 29.7 percent, respectively, received warfarin after discharge. A body-mass index (the weight in kilograms divided by the square of the height in meters) of 25 or greater was associated with rehospitalization for thromboembolism, with an odds ratio of 2.5 (95 percent confidence interval, 1.8 to 3.4). In a multivariate model, the only prophylactic regimens associated with a reduced risk of thromboembolism were pneumatic compression in patients with body-mass indexes of less than 25 (odds ratio, 0.3; 95 percent confidence interval, 0.2 to 0.6) and warfarin treatment after discharge (odds ratio, 0.6; 95 percent confidence interval, 0.4 to 1.0). CONCLUSIONS: In patients who underwent total hip arthroplasty, a body-mass index of 25 or greater was associated with subsequent hospitalization for thromboembolism. Pneumatic compression in patients with a body-mass index of less than 25 and prophylaxis with warfarin after discharge were independently protective against thromboembolism.

Arthroscopic laser surgery: a revisitation.

Laser surgery has been known for 38 years-since 1961. In relative terms, this short period of existence has produced a dramatic effect on medicine. We would anticipate a geometrically progressive increase in the use of laser tools over the next 100 years. Lasers will probably be used at lower levels of intensity in the future for two reasons: absence of complications and effectiveness as a noninvasive anti-inflammatory tool. Other electroinductive energy tools and other wavelengths will become increasingly important in medicine. This is true particularly in repair, soft-tissue surgery, photochemical therapy, anti-inflammatory therapy, and inductive therapy. The future is bright for laser and laser-related tools. As the price comes down, usage will increase dramatically. Soon, tissue-specific wavelengths will be available.

Photodynamic modulation of wound healing with BPD-MA and CASP.

BACKGROUND AND OBJECTIVE: Wound healing is an intricate process requiring the orchestration of cells, growth factors, cytokines, and the extracellular matrix. Cytokines, specifically TGF-beta, are believed to be instrumental in sustaining the fibrotic process, which leads to scarring. Photodynamic therapy (PDT) uses potent photosensitizers, which induce a wide range of effects on cells and the extracellular matrix. The influences of PDT on wound healing are not well known. STUDY DESIGN/MATERIALS AND METHODS: Seven full-thickness incisional wounds were placed on each of 24 hairless Sprague Dawly rats, three wounds on one flank serving as dark controls and four on the contralateral side treated with PDT. Wounds were created two days before, one hour before, or one hour after red light exposure with an argon ion pumped dye laser. Twelve rats were injected with 0.25 mg/kg or 0.5 mg/kg of the PDT drug, BPD-MA, and the other 12 with 5 mg/kg or 10 mg/kg of the PDT drug, CASP, 3 and 24 hours prior to irradiation of light, respectively. At low doses of both photosensitizers, animals were irradiated with 1, 5, 10, and 20 J/cm2. At higher doses of BPD-MA and CASP animals were treated with 10, 20, 50, and 100 J/cm2 of light. Wounds were examined each day for 14 days and noted for edema, erythema, inflammation, necrosis, and quality of scarring. Wounds were also photographed at day 0, 2, 5, 8, and 14 post-irradiation. All animals were sacrificed 14 days after irradiation and the wounds were evaluated by light microscopy. RESULTS: Grossly, animals treated with 0.25 mg/kg BPD-MA showed no effect with PDT. Animals treated with 0.5 mg/kg BPD, and 5 and 10 mg/kg CASP showed responses that varied with both light and drug dose. Erythema, edema, inflammation, and necrosis attributed to PDT were all observed, but there was no apparent influence of PDT on either the rate or final appearance of wound healing. Histologically, there were no apparent differences between treated and untreated sites, regardless of the drug, dose of light, or time of irradiation. CONCLUSION: A single PDT treatment given before or after skin wounds does not apparently alter wound healing even when PDT caused brisk inflammatory reactions. PDT may have effects that were not detected. We conclude that PDT does not greatly influence incisional skin wound healing in the rat model.

Photodynamic synovectomy using benzoporphyrin derivative in an antigen-induced arthritis model for rheumatoid arthritis.

Experimental photodynamic therapy (PDT) has recently been adapted for the treatment of inflammatory and rheumatoid arthritis. The biodistribution of benzoporphyrin derivative monoacid ring A (BPD-MA) and the effect of percutaneous light activation via intra-articular bare cleaved optical fibers was investigated using a rabbit-antigen-induced arthritis model. Qualitative evaluation of intra-articular photosensitizer clearance was performed with laser-induced fluorescence from 0 to 6 h following intravenous injection. The compound was rapidly taken up within the joint and then cleared steadily over the 6 h interval. Biodistribution was determined by fluorescence microscopy and spectrofluoroscopic extraction techniques 3 h following intravenous injection of 2 mg/kg BPD-MA. The biodistribution study demonstrated elevated levels of BPD-MA in synovium (0.35 microgram/g) and muscle (0.35 microgram/g). Fluorescence microscopy demonstrated presence of the compound within pathologic synovium but absence of the photosensitizer within meniscus, ligament, bone and articular cartilage. Tissue effects were evaluated histologically at 2 and 4 weeks posttreatment. BPD-MA-mediated PDT caused synovial necrosis in the region of light activation in 50% of treatment knees at 2 weeks and 43% at 4 weeks. No damage to nonpathologic tissues was observed. These studies indicate that selective destruction of synovium can be achieved by the light-activated photosensitizing agent BPD-MA without damage to articular cartilage or periarticular soft tissues. PDT needs to be further evaluated to optimize treatment parameters to provide for a new minimally invasive synovectomy technique.

Influence of light delivery on photodynamic synovectomy in an antigen-induced arthritis model for rheumatoid arthritis.

BACKGROUND AND OBJECTIVE: Minimally invasive synovectomy techniques have been unsuccessful due to lack of selectivity. The purpose of this study was to evaluate the potential of photodynamic therapy to destroy diseased synovium in an antigen-induced arthritis model. STUDY DESIGN/MATERIALS AND METHODS: Three sets of experiments evaluated the biodistribution and treatment effects of Photofrin (PF) in rabbits with bilateral knee antigen-induced arthritis. The first set of experiments evaluated the biodistribution of PF in articular tissues of 30 rabbits from 6-72 hours after systemic injection of 2 mg/kg. In the second series of experiments, light was delivered to the knee joint via cleaved optical fibers, whereas for the third, light was delivered via a 600 microm diffusion tip fiber. Tissues were harvested at 2 and 4 weeks posttreatment. RESULTS: The biodistribution experiments demonstrated maximal uptake in inflamed synovium at 48 hours and a lack of uptake in normal tissues. With bare cleaved fibers, necrosis was observed in one specimen at 2 weeks and was absent in all specimens at 4 weeks. In the third experiment, synovial necrosis was observed in 3 of 7 specimens at 2 weeks and 3 of 8 at 4 weeks. No damage to articular cartilage or periarticular tissues was seen with either mode of light delivery. CONCLUSION: These studies indicate that selective destruction of synovium can be achieved with PF and suggest that optimization of light delivery techniques will play an important role in development of this new technique.

The thermal properties of bovine joint capsule. The basic science of laser- and radiofrequency-induced capsular shrinkage.

Orthopaedic surgeons have recently adapted the holmium: yttrium-aluminum-garnet (YAG) laser for the shrinkage of capsular tissues for treatment of glenohumeral instability. The molecular mechanism of capsular shrinkage has not been documented to date. This study examined the effects of heating on bovine calf knee capsule and subsequent shrinkage of the capsule. Capsule specimens were placed in a saline bath at temperatures ranging from 55 degrees to 75 degrees C for 1, 3, 5, and 10 minutes. Shrinkage was quantified by digital imaging, and the tissue was examined by light and polarized light microscopy. Tissue contraction was not measurable at or below 57.5 degrees C. At 60 degrees C, tissue shrinkage occurred with corresponding basophilic staining and loss of birefringence in collagen fibers. For specimens heated at 60 degrees C and 62 degrees C, shrinkage directly correlated with duration of thermal exposure. Maximal shrinkage of approximately 50% in length occurred at and above 65 degrees C with thermal exposures of 1 minute or greater. This study demonstrates that thermal shrinkage of bovine knee capsule correlates with denaturation of collagen fibers and depends on both time and temperature. Capsular shrinkage treatments may be performed with any energy source that is capable of well-controlled heating of capsular tissue and does not depend on the special properties of laser light.

Acute and chronic response of articular cartilage to holmium:YAG laser irradiation.

A Ho:YAG (holmium-yttrium-aluminum-garnet) laser system operating at a wavelength of 2.1 microns has been introduced recently for use in arthroscopic surgery. The acceptability of this new tool will be determined not only by its ability to resect tissue, but also by its long-term effects on articular surfaces. Two studies were performed to evaluate the acute and chronic effects of the laser on cartilaginous tissue. The acute in vitro effects of 2.1-micron laser irradiation were evaluated, including measurement of ablation efficiency, ablation threshold, and thermal damage in meniscal and articular cartilage. To document the chronic effects on articular cartilage in vivo, a 10-week healing study was performed. Eight sheep weighing 30 to 40 kg underwent bilateral arthrotomy procedures. Multiple full-thickness and partial-thickness defects were created. Animals were euthanized at 0, 2, 4, and 10 weeks. The results of the healing study showed (1) no healing of full- or partial-thickness defects in hyaline cartilage at 10 weeks; (2) fibrocartilaginous granulation tissue filling full-thickness defects at 2 and 4 weeks that was no longer evident at 10 weeks; (3) chondrocyte necrosis extending to > 900 microns distal to ablation craters at 4 weeks, with no evidence of repair at later dates; (4) chondrocyte hyperplasia at the borders of the damage zone at 2 weeks but not at euthanization occurring at later periods.

[Pneumothorax in laparoscopic cholecystectomy (I)]. / Pneumothorax während laparoskopischer Cholezystektomie (I).

A case of pneumothorax during laparoscopic cholecystectomy is reported. Etiology, evaluation and therapy are discussed.

Pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser ablation of fibrocartilage and articular cartilage.

A new, near-infrared, pulsed holmium laser (wavelength, 2.1 microns; pulse duration, 400 microseconds) was used to ablate bovine articular cartilage and meniscal fibrocartilage. Microscopic examination revealed zones of thermal damage extending 550 microns from ablation sites. Ablation rates were measured with a mass loss technique. Above threshold, mass removal rates were proportional to laser radiant exposure. Threshold radiant exposure for ablation was 50 J/cm2 for articular cartilage and 11 J/cm2 for meniscal fibrocartilage. Because the holmium laser can precisely and rapidly resect cartilaginous tissues with only moderate necrosis, function in a saline environment in direct contact with tissue, and be transmitted through conventional optical fibers, it has the potential to become a useful tool for the precise arthroscopic removal of intraarticular tissue.

The structure of the lipopolysaccharide core region of Citrobacter 027.

The structure of Citrobacter 027 lipopolysaccharide core has been established using sugar and methylation analyses and 1H-NMR spectroscopy, and was shown to be identical to the core described recently in PCM 1487 strain which represents a separate serotype in Citrobacter genus.

Complete 1H-NMR spectral assignments for globotriaosyl-Z- and isoglobotriaosyl-E-ceramide.

Two-dimensional scalar-correlated (COSY) 1H-NMR spectra of the title compounds, and phase-sensitive COSY spectrum of lactosylceramide, have been fully assigned and some spectral reassignments for related structures suggested. Glycosylation-induced shifts, and shielding by Z- and E-ceramide residues are discussed.

Citrobacter lipopolysaccharides: structure elucidation of the O-specific polysaccharide from strain PCM 1487 by mass spectrometry, one-dimensional and two-dimensional 1H-NMR spectroscopy and methylation analysis.

Structural studies on the O-specific polysaccharide of Citrobacter PCM 1487 lipopolysaccharide, using methylation analysis, Smith degradation and 1H-NMR spectroscopy, indicate that it consists of the trisaccharide repeating units (formula, see text) In this structure, 4-deoxy-D-araHex stands for 4-deoxy-D-arabino-hexose.

[Tramadol infusion anesthesia with the substitution of enflurane and various nitrous oxide concentrations]. / Tramadol-Infusionsanaesthesie mit Substitution von Enfluran und differenten Lachgaskonzentrationen.

The synthetic opioid tramadol was given to 40 patients during surgery according to a fixed, calculated infusion scheme. Anesthesia was started with thiopental and the patients were given different nitrous oxide concentrations via a semi-open system (group 1: 60%, group 2: 75%). The aim of this study was to clarify whether this anaesthetic procedure is practicable or whether it has grave disadvantages in comparison with the anesthesia models used so far. Furthermore we wanted to clarify whether under this infusion scheme the proportion of N2O in the inspiratory mixture is sufficient or whether higher concentrations are required. In 24 of 40 patients analgesia or the depth of anaesthesia was insufficient so that additional enflurane application was necessary. Postoperative respiratory depression in three patients had to be treated with naloxone. The advantages of this procedure are the safe and easy practicability, absence of significant changes in the haemodynamic parameters, good postoperative response of the patients and postoperative pain relief as well as the low incidence of postoperative side effects such as nausea, vomiting and CO2-retention.

Structure elucidation by one- and two-dimensional 360- and 500-MHz 1H NMR of the oligosaccharide units of two glycoproteins isolated from alveoli of patients with alveolar proteinosis.

The structure of the oligosaccharide units of the glycoproteins of Mr 36,000 and 62,000 isolated from alveoli of patients with alveolar proteinosis have been determined by one- and two-dimensional 1H NMR spectroscopy at 500 and 360 MHz. Bi-, tri-, and tetraantennary glycans of N-acetyllactosaminic type have been found in high percentage. They are 1----6 monofucosylated and fully sialylated, the ratio NeuAc(2----3)/NeuAc X (2----6) increasing with increasing degree of branching.

[Angina pectoris -- an early sign of water intoxication during transurethral prostatectomy (author's transl)]. / Angina pectoris -- ein frühes Zeichen des TUR-Syndroms.

Water intoxication from intravascular absorption of non-electrolyte irrigating fluid is a well-known and often serious complication of transurethral resection of the prostate. The amount of absorbed fluid depends on the duration of the operative procedure, the number of transected open venous sinuses and the hydrostatic pressure of the irrigating fluid. Arterial hypertension, bradycardia, mental agitation, confusion, headache, nausea, dyspnoea, convulsions and pulmonary edema are the typical syndromes. In this case, severe Angina Pectoris was the first alarming symptom.