Search results for "Pressure"

The Impact of Venous Pressure on FFR: Do Diuretics Affect FFR?

2016

Central venous pressure influences FFR measurements because it decreases the perfusion gradient distal to the stenosis proportionally more than it does proximal to it. The impact of central venous pressure is minimal for normal pressure values and for FFR values away from the threshold. However, in conditions where FFR is close to 0.80 and central venous pressure is high, it might play an important role in reclassifying stenoses from not relevant to relevant.

Information transfer and information modification to identify the structure of cardiovascular and cardiorespiratory networks

2017

To fully elucidate the complex physiological mechanisms underlying the short-term autonomic regulation of heart period (H), systolic and diastolic arterial pressure (S, D) and respiratory (R) variability, the joint dynamics of these variables need to be explored using multivariate time series analysis. This study proposes the utilization of information-theoretic measures to measure causal interactions between nodes of the cardiovascular/cardiorespiratory network and to assess the nature (synergistic or redundant) of these directed interactions. Indexes of information transfer and information modification are extracted from the H, S, D and R series measured from healthy subjects in a resting…

A nonlinear biomechanical model for evaluation of cerebrospinal fluid shunt systems.

1994

In view of complications arising from physical properties of cerebrospinal fluid shunts, a biomechanical model of hydrocephalus was set up to study in vivo parameters that may influence their function. These include: intracranial pressure, compliance and pulses, intrathoracic, intra-abdominal, and subcutaneous pressures, and the effects of siphonage and repeated valve flushing. Each of these factors was studied separately upon shunt implantation in the model. Results of testing of a sample low-pressure valve with antisiphon device conformed with consumer information in regard to valve opening pressure and pressure flow measurements. No customer information, however, was supplied concerning …

Histopathologic Findings in Early Encapsulated Blebs of Young Patients Treated With the Ahmed Glaucoma Valve

2010

Objective/aim Uncontrolled glaucoma presents a challenge for the ophthalmic surgeon especially in children and juvenile patients. For many patients who have undergone failed surgical procedures before, episcleral implants remain the last choice. Encapsulated blebs forming over antiglaucoma devices present a complication leading to malfunctioning or even failure with reincrease in intraocular pressure. We report our histopathologic findings of such blebs developing around the Ahmed glaucoma valve (AGV) after a short time period in young patients. Materials and methods Nine young patients (2 to 17 y of age) with otherwise uncontrollable glaucoma were treated with AGV (models FP-7 and FP-8, si…

Assessment of environmental AMD risk factors in a population of patients suffering from stroke and myocardial infarction

2010

International audience; Purpose: Stroke and myocardial infarction are common diseases occurring in patients suffering from Age Macular Degeneration (AMD). We assessed the rate of AMD and AMD risk factors in patients suffering from recent stroke or myocardial infarction. Methods: Patients suffering from a recent stroke or myocardial infarction (less than 1 month) benefited from a thorough ophthalmic examination with the following measurements and evaluations: visual acuity, intraocular pressure, fundus photography, Raman spectroscopy and macular OCT. In the same time a food questionnaire was dispensed. Finally, blood samples to measure fatty acids and lutein were performed. Results: 74 patie…

2017

Purpose Intraocular pressure (IOP) fluctuation is considered as a risk factor for glaucoma progression. We investigated IOP values and IOP fluctuation before and after trabeculectomy (TE) with mitomycin C (MMC) measured by 48-hour diurnal-nocturnal-IOP-profiles (DNP). Methods Pre- and postoperative DNPs of 92 eyes undergoing primary TE with MMC were analysed. Each 48-hour IOP-profile involved 10 IOP measurements (8:00 a.m., 2:00 p.m., 6:00 p.m., and 9:00 p.m. in sitting and at 00:00 in supine position). The “preoperative DNP” was performed a few weeks before TE. The “postoperative DNP” was performed at least six months (range: 6 months—2 years) after TE. Mean IOP values and IOP fluctuations…

Lipid profile of tenon's capsule in glaucoma patients

2009

International audience; Purpose: To provide data on the lipid profile of the Tenon’s capsule in Human glaucomatous eyes and to establish possible relationships with the short term outcome of filtration surgery. Methods: Fragments of Tenon’s capsule were collected during glaucoma surgery in patients suffering from open angle glaucoma (10 trabeculectomies and 17 non penetrating deep sclerectomies). The lipid profile of the human samples was determined by gas chromatography. A successful outcome after glaucoma surgery was defined by an intraocular pressure (IOP) ≤ 15 mmHg at 6 months without any IOP‐lowering agent. Results: We included 27 patients (12 males, 15 females) with a mean age of 65.5…

What Do We Really Know about the Effectiveness of Glaucoma Interventions?

2021

Purpose To identify systematic reviews of interventions for glaucoma conditions and to assess their reliability, thereby generating a list of potentially reliable reviews for updating glaucoma practice guidelines. Design Cross-sectional study. Participants Systematic reviews of interventions for glaucoma conditions. Methods We used a database of systematic reviews and meta-analyses in vision research and eye care maintained by the Cochrane Eyes and Vision United States Satellite. We examined all Cochrane systematic reviews of interventions for glaucoma conditions published before August 7, 2019, and all non-Cochrane systematic reviews of interventions for glaucoma conditions published betwe…

Long-term Results of Combined Cataract, IOL and Glaucoma Surgery

1994

OBJECTIVE: To determine the long-term intraocular pressure (IOP) control in patients that had undergone combined extracapsular cataract extraction (ECCE), lens implant and glaucoma surgery and compare the results obtained by the longer and shorter follow-up groups. STUDY DESIGN: Retrospective study of postoperative results with a minimum follow-up of one year, maximum of 10 years and a mean of 33.1 months. SETTING: Department of Opthalmology, ‘La Fe’ University Hospital. Department of Surgery of Valencia School of Medicine, Valencia, Spain. PATIENTS: Ninety-five eyes examined of 72 patients presenting coexisting cataract and glaucoma who underwent combined surgery in the last 11 years. MAIN…

Optical Coherence Tomography Characterization of Macular Changes Secondary to Arteriovenous Fistula

2017

Arteriovenous fistulas (AVFs) are abnormal shunts between the arterial and venous vascular systems. These usually produce ocular pain, increased intraocular pressure (IOP), and diplopia. Less frequently, they may cause retinal changes with visual impairment. Our purpose is to illustrate different retinal manifestations of AVF. We report the multimodal imaging study of three cases with retinal changes due to AVF, showing neurosensory retinal detachment, macular oedema, and macular ischemia. In conclusion, AVF may appear with different ophthalmic alterations. While usually increased IOP and diplopia are our main concerns, retinal study is mandatory, since a myriad of morphologic abnormalities…