The patency of the nasogastric (NG) tube should be checked every four hours and when substances are administered. Sometimes blockages will need to be cleared to maintain patency. The best practice for this is to use water or normal saline to irrigate the NG tube. The syringe can be used to break up the partial blockage. If this is ultimately ineffective, the NG tube may need to be replaced. Increasing the suction pressure is potentially dangerous as it may irritate the GI tract at the other end. pH testing is useful to confirm placement of the NG tube—it does not clear the blockage. A Valsalva maneuver increases intra-abdominal pressure, but this will have no beneficial effect on the sluggish NG tube.