Nasogastric (NG) aspiration is used to remove liquid contents from the stomach and decompress the stomach and small bowel. The need for NG aspiration often varies with the clinical presentation (Table 86-1). Gastric decompression is useful in small bowel obstruction, although some studies have shown that medical therapy with octreotide or somatostatin has allowed safe treatment of bowel obstruction associated with malignancy.^1,2 NG aspiration and decompression are no longer considered routine for the treatment of adynamic ileus.^3,4 Removal of liquid contents is useful in cases of GI bleeding, but not all patients with GI bleeding require NG aspiration.

In GI bleeding, a common and controversial situation for NG aspiration,⁶ aspiration of stomach contents can localize the source of bleeding, indicate the rate of bleeding, and clear the stomach for endoscopy. Patients with hematemesis virtually always have an upper GI source, and NG aspiration is helpful to assess the rate of hemorrhage rather than identify the source. In significant upper GI bleeding, such as suggested by refractory hemodynamic instability or large quantities of bright red bloody emesis, the rate of bleeding can determine the success of medical interventions and the need for emergent endoscopy. When the clinical picture suggests a slower rate of bleeding, such as with coffee-ground emesis or blood-streaked emesis, the need for NG aspiration is less clear because less sensitive methods of assessing the rate of hemorrhage, such as observation of spontaneous bleeding, hemodynamic assessment, and serial hematocrit measurement, are often adequate.

In patients without hematemesis, NG aspiration lacks sensitivity to detect an upper GI source.^7,8 Although it has been reported that 10% of patients with hematochezia have an upper GI source, many of these are from a duodenal source and are beyond the reach of the NG tube.⁹ Most patients with melena have an upper GI source and require upper endoscopy regardless of the results of NG aspiration. In severe, ongoing rectal bleeding with hemodynamic instability, NG aspiration is relatively useful because severe upper GI bleeding is generally easier to stop than severe lower GI bleeding.

The literature is riddled with case reports of bizarre mishaps resulting from the use of NG tubes, some of which are listed in Table 86-2. However, the rate of adverse effects has not been systematically addressed. The main morbidity from the procedure is probably related to pain, followed by epistaxis, both of which can be minimized by good technique.

The equipment required for NG tube insertion is listed in Table 86-3. The optimal positioning is with the patient seated upright with the neck slightly flexed. Topical application of anesthetic can reduce the pain of the procedure, and a vasoconstrictor can shrink the turbinates, creating a larger nasal opening, but use a vasoconstrictor with caution in hypertensive patients. One option is to mix 4% lidocaine with oxymetazoline and instill this solution using a nasal atomizer.¹⁰ Nebulized lidocaine also provides effective analgesia.¹¹ Although it is tempting to use viscous lidocaine on the tip of the tube instead of premedication, this maneuver does not allow time for the lidocaine to be effective. A right-handed operator may choose the right side or the side of patient preference. Premedication with IV metoclopramide, in adults, or lingual 24% sucrose, in infants, may also decrease pain.^12,13

Describing the procedure to the patient in advance and talking to the patient during the procedure minimize anxiety. Insert the lubricated tube into the selected nostril. Direct the tube posteriorly, not superiorly, and it should naturally bend inferiorly toward the glottis. Resistance is expected at the level of the glottis. At this point, have the patient take a drink of water, and advance the tube at the time of swallowing. This step minimizes the potential for false passage at the level of the glottis. Warming the distal tip of the tube will make it more pliable and may further decrease the pain of the procedure. Once the tube is past the glottis, quickly advance the tube and aspirate stomach contents. If the patient coughs during the procedure, stop and make sure that the patient can speak clearly. Failure to aspirate stomach contents should prompt visualization of the pharynx to ensure the tube is not coiled in the posterior pharynx. If the appearance of the gastric aspirate is inconclusive, its pH can be tested, or air can be insufflated during auscultation over the stomach (Table 86-4). A chest x-ray can also be obtained to confirm tube placement. If the NG tube is to remain in place, it can be taped to the patient’s nose and connected to low-intermittent suction.

Some situations make NG tube insertion more difficult, such as obstructed nares, lack of patient cooperation, or endotracheal intubation. In patients with obstructed nares, the orogastric route may be used, although this is often less comforTable than the NG route. In obtunded patients with a poor gag reflex, endotracheal intubation may prevent aspiration. In patients with endotracheal intubation, flexing the neck or cooling the tube in ice water to stiffen it may facilitate passage.

Anoscopy can identify an anorectal cause of bleeding in patients with hematochezia. Although an uncomforTable test, it is safe if performed properly. Contraindications include rectal foreign bodies and suspected rectal perforation. Anoscopy requires only an anoscope (a hollow plastic tube with a blunt obturator), lubricant, 4 × 4 gauze pads, blue absorbent pads (Chux^®), and a light source. Because both hands contact contaminated areas during anoscopy, an assistant can hold a hand-held light source, or the operator can use a forehead-mounted light.

Usually, the lateral decubitus position is least uncomfortable, although the knee-chest position is an alternative. The equipment can be assembled onto the blue absorbent pad on the bed. After a careful external visual inspection of the anus with retraction of the buttocks, the generously lubricated anoscope is gently inserted into the anus. Step-by-step verbal communication is essential. If resistance or pain is encountered, slowing the rate of insertion or redirecting can allow more comforTable passage. After insertion is completed, remove the obturator, obtain stool from the tip, and perform guaiac testing. Then peer through the anoscope as it is withdrawn, looking for potential sources of bleeding. Internal hemorrhoids are common sources of anorectal bleeding that are visible through the anoscope. After the procedure, the patient or operator may wipe off the lubricant with gauze and dispose of it in the blue absorbent pad.