Your hospital should have a written policy regarding flushing NG tubes.. That being said, if the obstruction is lessening there may not be any drainage. The NG may be blocked, if it's on continuous suction (that's how our physicians order it) it may be against the wall and the patient may need to change positions, or flushing may change the position (some will order intermittant suctioning just because of this). If it is a small-bore NG tube there may be particles too large for the tube that are blocking the tube; flushing will also help there, although changing to a larger size NG will help more-I let the physician decide. If the obstruction is resolving, there will be little or no drainage. Is the patient uncomfortable? Nauseated? Then check placement and flush. If the patient is not uncomfortable, you can still flush, but the amount of drainage may not increase.