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Thread: Phacodynamics:Bottle height,Surge,ABS tip and Venting video

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    Default Phacodynamics:Bottle height,Surge,ABS tip and Venting video


    An additional source of vacuum that builds up when the phaco tip is occluded. This is due to the tubing compliance. If a phaco needle is occluded and tubing collapses due to negative pressure. When occlusion breaks the rate of fluid exit from the anterior chamber can be temporarily increased due to the sudden expansion of the tubing. This can cause temporary shallowing until the fluid is replaced by the infusion
    Selecting lower levels of flow and vacuum will reduce the amount of surge.
    Rigid noncompliant aspiration tubing will also decrease the amount of surge. Another mechanism to reduce surge is venting. Venting allows vacuum levels to be equilibrated to air or fluid into the aspiration line. A system for venting exsits in all phaco machines.

    Phacodynamics:Bottle height,Surge,ABS Venting video attachment.php?attachmentid=209&stc=1&d=1434526201

    Bottle height :
    The inflow fluid originates in the irrigation bottle and is a balanced salt solution. The fluid travels from the irrigation bottle through plastic tubing, into the phaco needle and finally into the anterior chamber of the eye. To create a pressure gradient the bottle is placed at a height above the patient. When the pinch valve is open the fluid in the bottle and tubing creates pressure in the anterior chamber. Approximately 11 mm Hg pressure (above ambient atmospheric pressure) is produced intraocular for every 15 cm (6 inches) bottle height above the patient’s eye.

    The Aspiration Bypass System (ABS):
    is a small hole in the microshaft just below the flare of the tip. There is little or no flow through this port when the tip is unoccluded. As the tip becomes occluded and vacuum builds, more irrigation fluid is drawn through the ABS port, helping prevent any post-occlusion surge and anterior chamber collapse. Thus, high vacuum levels of more than 500 mm Hg are safely achievable. In addition, the extra fluid flowing through and around the tip (via the loosely fitting irrigation sleeve) allows extra cooling of the tip, helping prevent corneal burns.

    Venting :
    Another mechanism to reduce surge. Venting allows vacuum levels to be equilibrated to air or fluid into the aspiration line. A system for venting exsits in all phaco machines.

    this part of presentation covers :Bottle height - Surge - ABS tip - Vent

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