An orogastric tube (OG tube) is a flexible, hollow medical device inserted through the mouth to access the stomach. It provides a temporary pathway for various medical treatments, bypassing the normal swallowing process. OG tubes are primarily used in acute care settings for patients who cannot safely swallow or require immediate intervention to manage stomach contents. The choice of an OG tube over other methods often depends on the patient’s age or specific clinical condition.
Defining the Orogastric Tube and Its Function
The orogastric tube is a long, narrow tube constructed from flexible materials like polyurethane or polyvinyl chloride. Its diameter is measured in French (Fr) units, where one French unit equals one-third of a millimeter. Tube sizes vary widely; neonate tubes are small (5 to 8 Fr), while tubes for adult gastric lavage can be much larger (up to 50 Fr) to accommodate thicker fluids.
Once positioned in the stomach, the tube serves two primary mechanical functions. The first is enteral feeding, which is the delivery of nourishment and liquid medications directly into the gastrointestinal tract. The second is gastric decompression, which involves connecting the tube to a suction device to remove excess air, fluid, or unwanted stomach contents. Decompression helps relieve pressure and distension in the stomach, often beneficial in cases of bowel obstruction or after major surgery.
Distinguishing Orogastric and Nasogastric Tubes
The primary difference between an orogastric (OG) tube and a nasogastric (NG) tube is the route of insertion. The OG tube is inserted through the oral cavity, passing down the throat and esophagus, while the NG tube is routed through the nasal passage. This distinction dictates which patients benefit most from each device.
OG tubes are favored in the neonatal population because newborns are obligate nose breathers, and an NG tube could obstruct their limited airway. The OG route is also preferred for adults with facial or basal skull trauma that makes nasal insertion unsafe, or for patients already intubated for mechanical ventilation. Since the oral route is generally less comfortable and more stimulating, OG tubes are typically intended for short-term use, often for less than two weeks, before being replaced with an alternative feeding method.
Specific Medical Uses
OG tubes are chosen when rapid access is needed or when nasal obstruction must be avoided. For premature infants, the OG tube provides essential nutrition when they lack the coordinated suck-swallow reflex necessary for safe oral feeding. Infants receiving respiratory support via nasal Continuous Positive Airway Pressure (CPAP) must also use an OG tube, as an NG tube would interfere with the nasal prongs and compromise the breathing treatment.
In emergency medicine, the OG tube’s wider diameter capability makes it the standard choice for rapid gastric lavage, or “stomach pumping,” in cases of poisoning or drug overdose. The tube’s large bore allows for the efficient removal of substances or the administration of thick fluids like activated charcoal. For unconscious or intubated patients, the OG tube is often the safest option for temporary feeding or decompression, bypassing the need to navigate a potentially compromised nasal passage.
Placement and Verification
The insertion process begins by measuring the appropriate length from the patient’s mouth to the earlobe and then down to the xiphoid process to estimate the distance to the stomach. The lubricated tube is then gently guided through the mouth and into the esophagus until it reaches the predetermined depth. Proper placement requires immediate verification to ensure the tube has not inadvertently entered the lungs, which is a severe complication.
Multiple safety checks are performed, including aspirating fluid to check for gastric contents and testing the fluid’s pH level, which should be acidic (typically less than 5). While auscultation (listening for a gurgling sound over the stomach after injecting air) is sometimes used, it is considered an unreliable confirmation method. The most definitive method for confirming the correct position before the tube is used is radiographic confirmation, such as a chest and abdominal X-ray.