There are only two indications for changing or emptying
the container. The container is replaced when
the fluid is turbid (ie, cloudy or muddy in appearance,
with matter in suspension) or the container is
full. The water-seal chamber itself should not be
emptied unless the drainage container is full. If the
drainage container needs to be changed or emptied,
then the nurse must clamp the chest tube while the
water is changed and ensure that the water-seal
chamber is refilled to the marked level.