How to check residuals of Nasogastric (NG) / Oropharyngeal (OG) tube?

From the Guidelines

To check residuals from a nasogastric (NG) or orogastric (OG) tube, first gather your supplies including a large syringe (30-60 mL), pH paper, and a clean container, and follow a step-by-step approach to ensure patient safety and accurate assessment. When checking residuals, it is essential to prioritize the patient's safety and comfort. Begin by washing your hands thoroughly and explaining the procedure to the patient. Put on gloves for protection. The following steps should be taken:

• Disconnect the feeding tube from any feeding apparatus and clamp it to prevent leakage.
• Attach the large syringe to the end of the tube and gently pull back on the plunger to withdraw gastric contents.
• Observe the amount and characteristics of the aspirated fluid.
• Measure the volume of the residual contents in the syringe.
• If checking for proper tube placement, place a small amount of the aspirate on pH paper to confirm acidic pH (typically 1-5.5 for gastric contents) 1. Some key considerations when checking residuals include:
• Documenting the amount, color, and consistency of the residual.
• Notifying the healthcare provider if residuals are high (typically >250 mL, though guidelines vary by institution).
• Flushing the tube with 30 mL of water to maintain patency, unless contraindicated 1. Checking residuals is crucial to assess feeding tolerance, prevent aspiration, and confirm proper tube placement, though frequency of checks varies based on institutional protocols and patient condition. It is also important to consider the latest guidelines and recommendations, such as those from the ERAS society, which emphasize the importance of early mobilization, minimally invasive surgery, and opioid-sparing analgesia in reducing postoperative ileus and promoting patient recovery 1.

From the Research

Checking Residuals of NG/OG Tube

To check the residuals of a nasogastric (NG) or orogastric (OG) tube, the following steps can be taken:

• Check the tube placement: Verify that the tube is properly placed in the stomach or small intestine using methods such as air insufflation, CO2 detection (capnography), aspirate pH testing, or point of care ultrasound (POCUS) 2
• Aspirate gastric contents: Use a syringe to aspirate gastric contents from the tube to check for residual feeding or medication 3
• Measure gastric residual volume: Measure the volume of gastric contents aspirated to determine if it is within a normal range (typically less than 150-200 mL) 3
• Check for signs of feeding intolerance: Monitor patients for signs of feeding intolerance, such as nausea, vomiting, or abdominal distension, which may indicate a need to adjust the feeding regimen 4
• Use prokinetic agents: Consider using prokinetic agents, such as metoclopramide, to enhance gastric emptying and reduce residual volumes, although their effectiveness may vary 5, 6

Gastric Residual Volume

The amount of gastric residual considered "excessive" can vary, but a common threshold is 150-200 mL 3. If the residual volume exceeds this threshold, it may be necessary to:

• Hold feedings: Temporarily stop feedings to allow the stomach to empty 3
• Adjust feeding rate: Adjust the feeding rate to prevent overfeeding and reduce residual volumes 3
• Use prokinetic agents: Consider using prokinetic agents to enhance gastric emptying and reduce residual volumes 5, 6

Bedside Tests

Bedside tests, such as pH testing and CO2 detection, can be used to verify tube placement and detect complications 2. These tests can be used in conjunction with radiographic imaging to increase sensitivity and specificity for detection of improperly placed tubes.