Unsuitability of sump tubes for delivery of enteral nutrition and medications to intensive care unit patients

Abstract

16 Fr Salem Sump™ tubes have special features to facilitate suction drainage of the stomach, including a second lumen for air venting. These tubes are also commonly used to deliver enteral nutrition and medications to intensive care unit (ICU) patients, but we found no previous research to justify this practice. Because of the unused air vent, these tubes have a large external diameter and a small bore infusion channel (no larger than that of a single lumen 12 Fr feeding tube). The causes of 16 Fr Salem Sump tube obstructions in 17 ICU patients included clogged medications (8 cases) and precipitation of feeding formula (7 cases), each of which would be promoted by a narrow bore. Because of multiple drainage holes at their distal end, these tubes cannot be thoroughly cleansed by standard water flushing; moreover, their drainage holes mandate a deeper length of tube insertion beyond the gastroesophageal junction, which increases the likelihood of intestinal or pulmonary perforation. For these reasons, we conclude that 16 Fr Salem Sump tubes are inferior to standard feeding tubes for delivery of enteral nutrition and medications to patients in medical ICUs.

Keywords: Acid-induced precipitation of formula; Salem Sump tubes; complications of enteral nutrition; crushed medications; nasogastric tubes.

Figure 1.

Diagram of a Salem Sump tube. See text in Material and Methods for description. (a) General design. (b) Diagram of the double-lumen principle of suction. Reprinted from https://clinicalgate.com/nasogastric-and-feeding-tube-placement/; drawing courtesy of the Argyle Division of Sherwood Medical, St. Louis (now Cardinal Health).

Figure 2.

Top. Cross-sections of five nasogastric tubes that could be used to deliver nutrition and medications to ICU patients: (a) Covidien Salem Sump – 16 Fr, silicone, dual lumen stomach tube, infusion lumen is not circular (see text); (b) Covidien Salem Sump – 16 Fr, polyvinyl chloride, dual lumen stomach tube, internal diameter ∼2.7 mm; (c) Covidien Salem Sump – 14 Fr, polyvinyl chloride, dual lumen stomach tube, internal diameter ∼2.5 mm; (d) Covidien Kangaroo – 14 Fr polyurethane feeding tube, internal diameter ∼3.3 mm; (e) Covidien Kangaroo – 12 Fr radiopaque polyurethane tube, internal diameter ∼2.7 mm. Bottom. Effect of increasing French size on the internal diameter of single and double lumen nasogastric tubes. Increasing the external diameter of single lumen tubes (left) is associated with a comparable fractional increase in internal diameter. Increasing the external diameter of double lumen Salem Sump tubes (right) results in relatively little increase in internal diameter.

Figure 3.

Location and extent of clotting in 16 Fr Salem Sump tubes removed from ICU patients. The vertical scale is from 0 (tip of tube) to 122 cm (top of tube or infusion port). See Table 1 for demographic data on each case. The figure does not show cases #6 and #9, whose tubes contained no internal obstruction.

Figure 4.

Pathology of 16 Fr Salem Sump tubes which became obstructed in ICUs. (a) Hematoxylin and eosin (400×) stain shows flake-like pectin particles from case #2. (b) Cross-section from case #3 reveals complete obstruction from white, chalky material. (c) Polarized light (400×) microscopic picture from case #3 shows birefringent crystals that are consistent with compounding agents of an administered medication. (d) A linear section of the tube from case #17 shows a smooth tan formula precipitation clot obstructing the distal 14 cm of the tube. (e) Hematoxylin and eosin (400×) stain of amorphous proteinaceous material from a formula precipitation clot (case #1). (f) Case #9, where a permanent kink (blue arrow) 57 cm from the distal tip of the tube apparently resulted in obstruction.

Figure 5.

Effect of water flush on 16 Fr Salem Sump tubes in vitro. The top row shows entire tubes (a) filled with Osmolite, before flush, and (b) after 30 mL water flush, with diluted Osmolite present above the proximal aperture (arrow). More concentrated Osmolite is present within the distal chamber of the tube. The bottom row shows the proximal (top) and distal (bottom) ends of tubes after a 60 mL water flush. (c) The tube is better cleansed above the proximal aperture (arrow), but the distal compartment contains relatively concentrated Osmolite. (d) A silicone plug (arrow) was placed just distal to the proximal aperture, so Osmolite could not reach the distal chamber directly from the infusion channel. After a 60 mL water flush, the proximal tube is cleansed, but the distal chamber contains Osmolite.

Figure 6.

Appearance of the distal end of unmodified and modified 16 Fr Salem Sump tubes after separate infusions of Osmolite and acid (1 mEq/h HCl) into a beaker. (a) Distal end of the tube after all fluid drained by gravity. Above the proximal aperture (white arrow), the tube is empty. Below the proximal aperture, the tube contains clotted Osmolite within the infusion channel and only two of the distal apertures remain patent (red arrows). (b) A modified 16 Fr Salem Sump tube was created by inserting an air-tight silicone plug (red arrow) just distal to the proximal aperture (white arrow). This tube had been wiped and drained as described above. There were no clots within the proximal aperture or the infusion channel above it. The tube distal to the plug contained clotted Osmolite, and some of the apertures were obstructed. (c) A silicone plug was placed just distal to the proximal aperture, and the distal chamber with its multiple apertures was transected just below the plug. The modified tube contained a single aperture. The tube had been wiped and drained as described above. Despite acid-induced coagulation within the beaker and clots that surrounded the tube as in part (a) above, no formula clotting occurred within the infusion channel or in its single aperture. The solid white line (yellow arrow) is the radiopaque marker in the wall of the tube.