Nasogastric Tube Design to Reduce Clogging and Simplify Flushing

Herein we present a new helical slit tip for the nasogastric (NG) tube to reduce clogging, as well as an accompanying modular in-line flusher to simplify flow restoration to a clogged tube. Nasogastric tubes are one of the most ubiquitous medical devices used in urgent and intensive care situations. Most commonly used to evacuate the stomach during cases of small obstructive bowel syndrome and surgical operations, the NG tube is prone to clogging. A detailed analysis of nasogastric tube obstruction in an ex vivo model was performed. The proposed NG tube tip is an improvement over the current state of the art. Clogging by suction to the mucosa is prevented by the continuous and helical nature of the suction area. Clogging by food particles is avoided by introducing slits rather than holes, and thus inhibiting close packing and clogging of the particulate on the suction tip. The modular in-line flusher is a device which combines into one push the many steps a caregiver usually takes to unclog the tube via flushing, with no disconnections required. Use of the redesigned NG tube and modular in-line flusher will reduce the need to troubleshoot and replace NG tubes, saving care providers’ time, reducing hospital costs, and reducing patient discomfort. INTRODUCTION The redesign of the NG tube tip and development of a modular in-line flusher were motivated by the frequent clogging of the nasogastric tube. The use of NG tubes in medical care is pervasive; nasogastric intubation is one of the most common procedures performed in emergency rooms and operating theatres around the country. Unfortunately, NG tube placement has also been reported to be the most painful procedure performed in emergency departments [1]. Since the late 18 th century, negative pressure through a tube has been used to evacuate stomach contents from patients [2]. While improvements have been made to materials to allow for flexible yet patent tubes, improvements to the design of the NG tube have primarily been incremental. The major exception is the introduction of the bilumen tube, which added a second lumen, called a sump line. This second lumen allows air into the stomach to reduce the chances of adhering tightly to the stomach mucosa. The Salem SumpTM NG tube by Covidien (see Figure 1) is the most popular NG tube in the U.S. market today [3]. FIGURE 1: CURRENT NG TUBE. A) SALEM SUMPTM NG TUBE BY COVIDIEN [3]. B) CROSS SECTION OF NG TUBE SHOWING TWO LUMENS. UPPER LUMEN IS SUMP LINE AND LOWER, CIRCULAR, LUMEN IS SUCTION LINE. Clinical Indications for Nasogastric Intubation There are several medical indications that call for the placement of an NG tube. The most common conditions are small bowel obstruction (SBO) and upper gastrointestinal bleeding. See Figure 2 for a diagram of NG tube placement. SBO occurs when intestinal content flow is obstructed by A B 1 Reprinted with permission of James A. Ankrum, Jose A. Canseco, Elliot E. Greenblatt, Alison L. Olechowski, Michael P. Roberts, Nevan C. Hanumara, Alexander H. Slocum, Ali Tavakkolizadeh a distal defect. The main mechanical cause of SBO is the presence of adhesions, which are abnormal bands of scar tissue that can form after surgery [4]. Approximately 30% of patients that undergo lower abdominal surgery will develop SBO due to adhesions [4]. Tumors of the abdominal cavity can also lead to SBO, accounting for about 20% of cases [5]. Hernias, abnormal protrusions of intestinal tissue through abdominal or pelvic structures, are the cause of about 10% of SBOs [5]. Finally, several medical conditions that cause the narrowing of the intestinal lumen can lead to SBO [6]. For SBO, NG tubes are used to decompress the stomach and relieve distention, providing comfort for the patient. Upper gastrointestinal bleeds also call for the use of NG tubes. In this case, NG tubes are used as a cleaning device, helpful in removing solid contents as well as clots and blood from the stomach. This is useful in assisting the healthcare team to locate and confirm the source of bleeding [7, 8]. Finally, NG tubes are currently used routinely to drain the stomach following uncomplicated gastrointestinal surgeries. Drainage with NG tubes provides bowel rest for the patient while their gastrointestinal system recovers from the surgery, and prevents respiratory complications associated with anesthesia. FIGURE 2: PLACEMENT OF NG TUBE. Complications associated with NG tube placement have been well documented. Blind placement of NG tubes has led, in a small number of patients, to serious and sometimes lifethreatening complications including pneumothorax, atelectasis, enteric perforation, and intracranial placement [911]. There has been much debate over the past decade over the appropriate use of NG tubes [12]. Design Motivation This design sought to address problems that frequently arise during clinically appropriate use of the NG tube. Two main risks cause malfunction of the NG tube after placement: 1) adhesion to the stomach mucosa and 2) obstruction of the lumen by solid particles. These complications are everpresent, so much so that manufacturers of NG tubes recommend prophylactic flushing of the tubes on a regular basis. Furthermore, any healthcare practitioner or patient can attest to the unpleasant experience of having to replace a malfunctioning NG tube. Current remedies to these complications involve intervention by a caregiver who first uses a syringe to force 10-15 cc of air down the sump line to help break the seal of the tube against the stomach wall. If the obstruction persists, the vacuum line is disconnected and 10-20 cc of water or saline is injected directly down the suction port. If this second attempt fails to restore function, the NG tube is removed and a new tube is placed [13]. These complications motivated the proposed NG tube redesign and modular in-line flusher. DESIGN REQUIREMENTS Based on knowledge of the current NG tube frustrations listed above and discussions with medical practitioners who use NG tubes on a regular basis – including nurses, emergency room doctors, and surgeons a list of design requirements was compiled. We sought to design and create a means of decompressing the stomach that met the following solution requirements: 1. Safe for the patient – as with all medical products, the product must do no harm to the patient. The failure mode must be “do nothing” and not harmful. 2. Reduce clogging – with a more reliable means of decompressing the stomach there is less need for replacing and troubleshooting NG tubes. Reduction of tube replacement improves patient safety. 3. Easy to unclog less of the care-providers’ time is taken in unclogging blocked tubes. 4. Uses same placement technique as current NG tube – does not require extensive training or drastic change from current practice. The procedure for placing the NG tube must be acceptable to clinical practice. 5. Inexpensive – the current solution is very inexpensive (approximately $1) and so for a product of similar application, a large increase in price is to be avoided. 6. Comfortable for the patient – the placement of NG tubes is already a painful experience. The present solution must not increase the discomfort to the patient during placement or decompression and should minimize the need for the tube to be replaced. In order to best achieve these design requirements, a twopronged solution was developed: a redesigned nasogastric tube tip and a modular in-line flusher.