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[Adjuvants to nonpenetrating surgery: drains and implants].

The nonpenetrating filtering procedure requires a functioning intrascleral space. This space is created after a careful dissection and resection of the deep scleral flap. In order to prevent a collapse of the remaining superficial flap that forms the roof of the intrascleral cavity, a space maintainer is usually inserted at this stage of surgery. Two different types of drainage devices are used: absorbable and nonabsorbable implants. The first type is currently made of porcine collagen material that is slowly absorbed over time, whereas the second is usually made of nondegradable materials that permanently remain in the scleral bed. No significant differences in the surgical technique can be found between the two types of implant. The long-term results are fairly similar for both of them, the absorbable implant being slightly more advantageous.

Dissection↗

Filtering blebs imaging by optical coherence tomography.

PURPOSE: To assess the ability of standard optical coherence tomography to visualize filtering blebs after glaucoma surgery. METHODS: A prospective interventional case series was conducted in a private practice. Twenty-nine eyes of 24 patients (21 with good, 2 with fair and 6 with poor intraocular pressure [IOP] control) were investigated. After the focus was manually adjusted on the conjunctiva, blebs were scanned perpendicularly to the limbus. RESULTS: Hyporeflective fluid-filled spaces were detected in 19 out of the 21 eyes with good IOP. Within this group, blebs were classified into three different categories according to their optical coherence tomography pattern: type A (featuring a thick wall and a single large fluid-filled space), type B (featuring a thin wall and multiple large fluid-filled spaces) and type C (featuring multiple, irregular and flattened fluid-filled spaces). Fluid-filled spaces were not observed in three out of the six eyes with poor IOP control. Trabeculectomy without antimetabolites was associated with type A blebs (P = 0.015, Fisher's exact test), mitomycin-C trabeculectomy with type B blebs (P = 0.0025) and mitomycin-C phacotrabeculectomy with type C blebs (P = 0.0173). CONCLUSIONS: Although it was not developed to evaluate the anterior segment of the eye, standard optical coherence tomography can visualize filtering blebs and reveal interesting details of their morphology. Clinicians using optical coherence tomography to diagnose glaucoma can take advantage of this ability of the instrument to obtain more information about their patients in the postoperative course of trabeculectomy and phacotrabeculectomy.

Adolescent↗

Trabeculectomy in young Nigerian patients.

The results of 89 trabeculectomies performed on 56 patients under the age of 30 years were reviewed. Data collected included age, sex, type of glaucoma, number of years of glaucoma before surgery, visual acuity, intraocular pressure, complications of surgery, presence of a filtering bleb and follow-up period. Complete success, denoted by a postoperative IOP of 21 mmHg or less without medical therapy, occurred in 50 eyes (56.2%). Qualified success, in which IOP was 21 mmHg or less with additional medical therapy occurred in 31 eyes (34.9%) and failure, in which IOP was greater than 21 mmHg in spite of medical treatment occurred in 8 eyes (8.9%). Success was therefore achieved in 91.1% attaining an IOP of 21 mmHg or less, with or without additional medical therapy. The most statistically significant factor was age groups in which the highest success rate of 100% was achieved in the age group 20-29 years. The difference in the success rate across the age groups was statistically significant (x2 = 8.04, p = 0.01). Fornix based conjunctival flaps were also found to be associated with a statistically significant higher success rate (97.9%) as opposed to limbal based flaps (85.4%), x2 = 4.81, p = 0.03. Males in the study group had a significantly higher success rate (97%) than females (78.3%), x2 = 5.86, p = 0.011. A success rate of 100% was recorded in patients with developmental glaucoma, 86.1% in congenital glaucoma and 33.3% in secondary glaucoma. All the repeat trabeculectomies had congenital glaucoma. The presence of a bleb, although it had a higher success rate (93.4%) compared with the absence of a bleb (84.6%), was not statistically significant (x2 = 1.19, p = 0.27). Complications of surgery were mostly transient.

Adolescent↗

Bedside placement of inferior vena cava filters in the intensive care unit.

The objective of this study was to determine the feasibility, cost-effectiveness, and complications of bedside placement of inferior vena cava (IVC) filters in the intensive care unit (ICU) in the trauma patient. A prospective trial involving 25 trauma patients admitted to Memorial Regional Hospital (Hollywood, Florida), a Level I trauma center, from April 1997 to April 1998, meeting the criteria for insertion of a prophylactic IVC filter according to Eastern Association for the Surgery of Trauma trauma practice guidelines was conducted. IVC filters were placed in the ICU with the use of a digital C-arm (Siemens) and strict adherence to sterile technique. Renal vein anatomy and size of the IVC were documented for every case. Charges for equipment and supplies were analyzed and compared with those placed in the radiology suite and the operating room. Of 810 patients admitted as trauma alerts during the study period, 25 had an IVC filter placed at the bedside in the ICU. The indications for filter placement included a contraindication to anticoagulation and one of the following: severe pelvic fracture and/or associated long-bone fracture (32%); bilateral lower extremity fractures (28%); spinal cord injury with para- or quadriplegia (16%); femoral vein thrombosis (16%); and severe brain injury (8%). There were no intraoperative nor postoperative complications; overall mortality was 20 per cent, unrelated to the IVC filter placement. Average time for insertion was 47 minutes for the series and 20 minutes for the last five cases. Savings of $1844 or $2245 per filter are obtained when IVC filters are placed in the ICU when compared with the operating room or radiology suite, respectively. Bedside placement of IVC filters in the ICU is a safe, cost-effective method that can be performed without compromising the patient and avoids the potential disasters involved in transporting critically ill patients.

Adult↗

Failure of bacterial filters to reduce the incidence of pneumonia after inhalation anesthesia.

The authors prospectively studied 520 patients undergoing inhalation anesthesia to evaluate the efficacy of low resistance 0.22-micron bacterial filters in preventing postoperative pneumonias. Patients undergoing elective thoracic, upper abdominal and lower abdominal surgeries were randomly assigned preoperatively to filtered and nonfiltered anesthesia circuits by a study nurse. A second study nurse, who was unaware of patient assignments, followed each patient for five postoperative days to identify possible pulmonary complications. Both groups of patients were similar in age, sex distribution, smoking history, prior pulmonary disease, types and duration of surgery, ASA physical status classification, and receipt of intraoperative antibiotics. No differences in rates of postoperative pneumonia were observed between patients assigned to filtered and nonfiltered circuits (16.7 per cent vs. 18.3 per cent, respectively, P = 0.73). Also no differences were observed when the incidences of other outcome criteria such as postoperative fever, abnormal chest x-ray, sputum production, or abnormal pulmonary physical exam findings were evaluated. The results suggest that bacterial gas filters do not influence the incidence of postoperative pneumonias and that routine use of these devices for this purpose is not cost-effective.

Anesthesia, Inhalation↗

Bone enhancement filtering: application to sinus bone segmentation and simulation of pituitary surgery.

We present a novel multi-scale bone enhancement measure that can be used to drive a geometric flow to segment bone structures. This measure has the essential properties to be incorporated in the computation of anatomical models for the simulation of pituitary surgery, enabling it to better account for the presence of sinus bones. We present synthetic examples that validate our approach and show a comparison between existing segmentation techniques of paranasal sinus CT data.

Algorithms↗

Chronic pulmonary thromboendarterectomy complicated by antithrombin III deficiency and antiphospholipid syndrome.

Pulmonary thromboendarterectomy was performed on two patients with chronic pulmonary thromboembolism showing thrombotic tendency. Patient 1 was a 25-year-old male with the disease complicated by congenital antithrombin III deficiency. Patient 2 was a 21-year-old male with the disease complicated by antiphospholipid syndrome. Both patients were admitted to the center upon showing dyspnea. Lung perfusion scintigraphy revealed multiple defects in the right and left lungs. Pulmonary arteriography showed occlusion and stenosis from lobar to segmental arteries. Cardiac catheterization showed marked pulmonary hypertension. Pulmonary angioscopy confirmed the presence of organized thrombi while an intravascular ultrasound revealed a thickening of the pulmonary arterial walls in both lungs. After the insertion of an inferior vena cava filter in each patient, surgery was performed. Following a median sternotomy, a cardiopulmonary bypass was utilized to induce deep hypothermia at a pharyngeal temperature of 16 degrees C, after which a thromboendarterectomy of the bilateral pulmonary arteries was performed under intermittent circulatory arrest. A large amount of organized thrombi was extracted from these arteries. After surgery, both patients showed good postoperative outcome with improved blood flow in both lungs, reduced pulmonary arterial pressure and increased cardiac output.

Adult↗

Encephalopathy and Stroke After Coronary Artery Bypass Grafting.

Both stroke and encephalopathy are associated with significantly longer lengths of stay in the hospital and with significantly higher rates of mortality. Those at risk for either stroke or encephalopathy, or both of these adverse outcomes after surgery, can be identified prior to surgery using information available to physicians. For those at higher risk for these outcomes, we suggest the following: 1) An imaging study of the brain, performed prior to surgery, may indicate the degree of cerebrovascular disease. At present we do not have this information on most patients. 2) The status of arteriosclerotic disease of the aorta should be determined prior to surgery or at the time of surgery. 3) For those with significant aortic and cerebrovascular disease, alternatives to the conventional ways of performing coronary artery bypass grafting (CABG) should be considered. These alternatives include percutaneous transluminal coronary angioplasty, off-pump surgery, and CABG using filters or inputs from the pump that selectively protect the brain.

Journal Article↗

[Deep nonpenetrating sclerectomy: technical aspects].

Classical trabeculectomy is affected by numerous and serious drawbacks that have led to the development of nonpenetrating surgery. In this new filtering technique, the aqueous outflow through the juxtacanalicular trabeculum and Schlemm's canal is selectively increased without penetrating the anterior chamber. This is best performed by means of a careful and precise dissection of the outflow resistance pathway and by removing its most resistant portion. This requires both mastery of the microdissection technique and high-precision surgical tools. Finally, sound knowledge of the morphological features of such delicate structures is of paramount importance to avoid intra- and postoperative complications.

Glaucoma↗

Cerebral embolisation during modern cardiopulmonary bypass.

OBJECTIVES: Cerebral microembolisation still occurs during cardiopulmonary bypass and may cause both stroke and postoperative cognitive impairment. We investigated the frequency of cerebral embolisation during coronary artery bypass surgery with modern cardiopulmonary bypass and related these to ascending aortic atherosclerosis. METHODS: Transcranial Doppler monitoring for cerebral embolisation to both middle cerebral arteries was performed in 65 patients undergoing coronary artery surgery with non-pulsatile alpha-stat hypothermic bypass. Epicardial ultrasound imaging of ascending aortic atherosclerosis was performed in 14 patients. RESULTS: Thirty patients (56.9%) had more than 200 emboli entering the middle cerebral artery territories during surgery; most at the start of bypass and during defibrillation. Readjustment of aortic clamps and aortic cannulation also caused a large number of emboli which were probably particulate. Aortic disease was mild (mean plaque thickness 1 mm, interquartile range 0.9-1.2 mm) and did not relate to the number of cerebral emboli produced by aortic manipulation. CONCLUSIONS: Cerebral embolisation remains common during coronary surgery despite advances in filter and bypass pump technology. Aortic manipulation and clamping was associated with emboli but epicardial ultrasound imaging was of little help in its prediction.

Adult↗

Evaluation of the stability of extemporaneously prepared ophthalmic formulation of mitomycin C.

Mitomycin C (MMC) is a cytostatic agent topically used in conjunctival neoplasms, secondary to glaucoma filtering, pterygium, and strabismus surgery to increase the success rate. The topical formulation of MMC for ocular use is always extemporaneously prepared. Our study evaluated the stability of extemporaneously prepared formulations of MMC at different concentrations (150, 300, & 600 microg/mL) kept at different temperatures (25 degrees , 4 degrees , and -70 degrees C) and at different pH range (6, 7, and 8). Aliquots from the above formulations were subjected for quantification of MMC on days 0, 7, 14, 21, and 28 using high-performance liquid chromatography. MMC stored at 25 degrees C for 6 months was also subjected to flow cytometry and compared to freshly prepared MMC. The results indicated that the degradation of MMC is very high in acidic pH at room temperature. Increasing the pH to 7 or 8 and keeping MMC at low temperatures significantly decreased the degradation of MMC. Interestingly, the flow cytometry data revealed that the 6-month-old MMC showed an antiproliferative effect compared to that of freshly prepared MMC. To conclude, the extemporaneously prepared MMC at pH between 7 and 8 and stored in the refrigerator can increase the duration of its stability. However, the antiproliferative study using flow cytometry revealed that degraded MMC retained its activity even after degradation.

Antibiotics, Antineoplastic↗

Postoperative changes in platelet adhesiveness.

Platelet adhesiveness was measured in patients undergoing operation. With the rotating bulb technique adhesiveness increased steadily to the sixth and ninth days following surgery. The glass bead filter technique demonstrated a marked increase in platelet adhesiveness on the day following operation.

Blood Cell Count↗

Latanoprost stimulates secretion of matrix metalloproteinases in tenon fibroblasts both in vitro and in vivo.

PURPOSE: To investigate the presence and the possible role of different matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in Tenon capsule fibroblasts. These enzymes are essential for the control of tissue remodeling in the context of wound repair. This aspect is important to further the understanding of and possibly to influence the scarring process of filtering blebs after glaucoma surgery. METHODS: Untreated and latanoprost-treated human Tenon fibroblasts were examined for the presence of MMPs and TIMPs on the mRNA and protein levels. Assays performed included RT-PCR, real-time RT-PCR, immunocytochemistry, Western blot analysis, flow cytometry, and zymography. To investigate the changes in vivo, conjunctival specimens of rabbits treated with latanoprost eye drops were examined by immunohistochemistry. RESULTS: In all assays, both MMP-3 and TIMP-2 were detected. With the real-time RT-PCR technique, MMP-1, -2, -3, -7, -9, and -14 and TIMP-1 and -2 were detected. An upregulation of MMP-3 and TIMP-2 after latanoprost treatment of the fibroblasts was shown and found to occur on the mRNA and the protein levels. The upregulation of MMP-3 and TIMP-2 was confirmed in vivo. CONCLUSIONS: Tenon fibroblasts contain the ability on the mRNA level to synthesize all enzymes of the MMP and TIMP family that are related to remodeling of the extracellular matrix. The levels of MMP-3 and TIMP-2 increase after treatment with latanoprost. Tenon fibroblasts may be the target cells for attempts to influence the tissue levels of MMPs and TIMPs in the context of conjunctival wound healing after glaucoma surgery.

Animals↗

Bone enhancement filtering: application to sinus bone segmentation and simulation of pituitary surgery.

The simulation of pituitary gland surgery requires a precise classification of soft tissues, vessels and bones. Bone structures tend to be thin and have diffuse edges in CT data, and thus the common method of thresholding can produce incomplete segmentations. In this paper, we present a novel multi-scale sheet enhancement measure and apply it to paranasal sinus bone segmentation. The measure uses local shape information obtained from an eigenvalue decomposition of the Hessian matrix. It attains a maximum in the middle of a sheet, and also provides local estimates of its width and orientation. These estimates are used to create a vector field orthogonal to bone boundaries, so that a flux maximizing flow algorithm can be applied to recover them. Hence, the sheetness measure has the essential properties to be incorporated into the computation of anatomical models for the simulation of pituitary surgery, enabling it to better account for the presence of sinus bones. We validate the approach quantitatively on synthetic examples, and provide comparisons with existing segmentation techniques on paranasal sinus CT data.

Algorithms↗

[Mass screening for glaucoma].

Mass-screening of the population over 40 years by tonometry is not recommended for developed countries. However, tonometry of each patient attending the ophthalmologist, is absolutely necessary. Omitting tonometry is only justified, if special reasons prevent it, for example inflammations. If reading-glasses are always prescribed by the ophthalmologist and tonometry is done on each such patient, then this is the adequate and sufficient protection of the population against glaucoma blindness. Preventive examinations of the group in the highest danger to become blind from glaucoma, i.e. persons of 55-65 years of age, might perhaps be useful, if the tonometric limit is set high (30 mmHg) and if a check of the visual field by the Friedman-Analyzer is combined with tonometry. The aim of such examinations would not be the detection of suspicious or very early forms (tonometric glaucoma), but to screen for definite glaucoma cases with field-defects, which undetected would become blind. It seems, however, questionable, if the motivation of this age group will be sufficient. This should be found out by pilot-tests. In developing countries the question of mass-screening is entirely different. There glaucoma patients must be filtered out, in whom surgery is less risky than waiting without treatment. This can only be done by mass-screening including tonometry by the borderline-tonometer glaucotest, perimetry by the Friedman-Analyzer and estimation of the cup/disc-ratio.

Aged↗

[A new approach towards pathogenesis and treatment of massive suprachoroidal hemorrhage].

A massive suprachoroidal hemorrhage is a well-known, possibly serious complication of a variety of surgical procedures such as cataract extraction, penetrating keratoplasty, glaucoma-filtering operation, retinal detachment surgery and pars plana vitrectomy. It is defined as a hemorrhage, in the suprachoroidal space, of sufficient volume either to cause extrusion of intraocular contents outside of the eye or to force the inner retinal surfaces into apposition ("kissing"). Despite surgical interventions to drain the hemorrhage and establish normal anterior and posterior anatomic configurations to return of preoperative visual acuity is hard to prognosticate. This paper presents the current knowledge on the pathogenesis, risk factors, treatment of massive suprachoroidal hemorrhage.

Choroid Hemorrhage↗

[Ability of leukocyte reduction filters to remove fat particles from blood in experimental models simulating blood salvage in orthopedic surgery].

BACKGROUND: Salvaged autologous blood in orthopedic surgery may contain tissular debris such as fat particles (FP), possibly increasing the risk of fat embolism after bone surgery. Therefore, this study was initiated to ascertain the capacity of leukocyte filters to remove FP using in vitro models. METHODS: All experiments were performed in triplicate using donor blood bags within 15 days of their donation. Five different olive oil volumes were added to blood to obtain 5 oil concentrations (1% to 5%), and blood was subsequently filtered through a PureCell (Pall Biomedical, Portsmouth, UK) leukocyte-reduction filter. In another set of experiments, 5 different oil volumes (1, 2.5, 5, 7.5 or 10 mL) were injected into the line during filtration of oil-free blood. In addition, 3 preparations of blood supplemented with 5% oil were processed in the autotransfusion device OrthoPAT (Haemonetics Corp, Braintree, MA, USA), and the obtained red cell concentrate was subsequently filtered through PureCell. We collected samples for cell counting and analysis and FP detection with a Pentra 120 Retic (ABX, Montpellier, France) flow cytometer. RESULTS: Specific signals corresponding to FP were clearly detected in the white blood cell scattergrams yielded by the cytometer for oil supplemented blood. PureCell removed FP up to an oil concentration of 3% or up to an injected oil volume of less than 10 mL. Addition of a filtration step through a PureCell filter after blood washing by the OrthoPAT device completely removed FP. CONCLUSIONS: Leukocyte filters seem to be useful for removing FP from unprocessed blood with a low degree of fat contamination (less than 10 mL) and to complete FP removal from processed blood. Therefore, using a leukocyte filter in the patient's line should contribute to improving the safety of perioperative autologous blood salvage.

Fats↗

Multidisciplinary approach to venous thromboembolism.

Venous thromboembolism shows a high incidence and a significant mortality. Even if valid methods are available, thromboembolism is underdiagnosed. There are a number of diagnostic difficulties. They concern the time of the diagnostic suspicion, the patient selection for the various procedures and their combination. These difficulties may be overcome by team work where specialists of different disciplines (surgeons, internists, experts in nuclear medicine, radiologists) integrate their competence to attain the established objectives. The integration results in "synergism", namely an added value greater than the sum of competences of the team components. Thus, an operational unit active 24 hours over 24 must be formed to diagnose and treat the largest number of cases of thromboembolism. To establish the clinical suspicion of thromboembolism is the first indispensable step for patient selection. Thromboembolism should be investigated in all patients with chest pain, dyspnea and tachypnea in the absence of preexisting cardiorespiratory disease. The team should evaluate the impact of signs and symptoms to establish a definitive clinical probability which can direct towards the suitable, least invasive imaging procedure. Perfusion scanning, when highly suggestive or normal, is conclusive. However in 70% of cases it is indeterminate. Thus it should be combined with other procedures and with the clinical assessment. In practice, many dubious cases remain unsolved. The team work represents an organizational response to this diagnostic and therapeutic inadequacy. The real change in strategy which has revolutionized the diagnosis of thromboembolism was the widespread use of color Doppler US in the diagnosis of deep vein thrombosis. Since pulmonary embolism as well as deep vein thrombosis are treated with the same therapy, it is adequate to document the thrombosis also in the absence of a definitive demonstration of embolism. The old-fashioned approach should be reversed and the investigation should be centered on the assessment of deep vein thrombosis: site, emboligenic potential, floating extremity and extension. The integration of the clinical assessment, scanning finding and color Doppler US lowers by about 20% the number of indeterminate cases and indicates the patients for whom pulmonary spiral CT or pulmonary angiography is required. In all patients with cardiorespiratory insufficiency still unsolved after the combination of noninvasive exams, pulmonary angiography or spiral CT is mandatory because of the high risk for death. The remaining ones can be followed with serial color Doppler US exams. The cost/benefit ratio shows that the noninvasive strategy is the least expensive, the least hazardous and the most effective. At present, effective therapies are available for thromboembolism. Standard heparin and low molecular weight heparin fractions, fibrinolytic agents, surgery and recently caval filters are playing a major role in secondary prophylaxis of pulmonary embolism. The therapeutic approach is conditioned by various factors: the features of thrombosis, the presence and entity of pulmonary embolism, the patient cardiorespiratory condition, possible contraindications for anticoagulant and fibrinolytic agents. The presence of such a number of variables makes the use of a therapeutic algorithm, difficult. In this phase, based on our experience we believe that the present solution lies in the activity of an operational team of experts who establish the treatment to be performed.

Cost-Benefit Analysis↗