Verify a nasogastric tube before a feed — OSCE

Candidate brief

You have eight minutes to verify a four-year-old's nasogastric tube before a feed. Use a structured approach: aspirate and test the pH with the indicator strip, read and state the exact value, decide and defend whether to feed or to escalate, document the verification correctly, and explain the plan and the safety reason to the bedside nurse and to the parent in plain language. The aspirate reads pH 6. [1]

Key teaching and decision objectives

Read the value, then decide. Aspirate the tube and apply the aspirate to a CE-marked pH indicator strip, reading the value at the time the manufacturer states. The aspirate reads pH 6. The accepted bedside rule is that a pH of 5.5 or less confirms gastric placement and is the green light to feed; a reading above 5.5 means the tube may be in the airway, the duodenum, or bathed in acid-suppressed or diluted gastric contents, so the feed does not go down. [1] [4]

Recognise and reject the deprecated method. The nurse's suggestion to use the whoosh test must be declined. The whoosh or air-insufflation test, the bubbling test, litmus paper, and auscultation used alone were retired because none reliably separates a gastric from a respiratory tube, and using any of them as the sole check is part of the Never Event. The correct confirmation is aspirate pH at 5.5 or less, with a radiograph when the pH is above 5.5 or no aspirate can be obtained. [3] [9]

Escalate, do not feed, and document. Because the pH is 6, reposition the tube and re-attempt aspiration once. If the pH is still above 5.5 or aspirate is still absent, request a radiograph that shows the whole course of the tube and its tip below the diaphragm over the stomach, interpret it, and document before any feed. Record the method used, the exact pH value (here, 6), the radiograph request and its result, the length of tube at the naris, and the date and time, so the next clinician inherits a decision and not a habit. [1] [4]

Communication to the nurse and the family

To the nurse (plain language): "Thank you for checking. We will not use the whoosh test here, because the national guidance retired it some years ago; it cannot reliably tell a stomach tube from a lung tube, and feeding after a whoosh-only check counts as a Never Event. The correct check is the pH strip, and a value of 5.5 or less is the green light to feed. This aspirate reads 6, which is above 5.5, so we do not feed yet. Let us reposition and re-aspirate once; if it still reads above 5.5, we request an X-ray to confirm the tip is in the stomach before any feed goes down. Please record the exact pH number, not just that it was checked." [3] [9]

To the parent (plain language): "Before anything goes down his tube we check it is sitting in his stomach and not somewhere it could do harm. We do that with a small sample from the tube and a pH strip; if it reads 5.5 or less, we know the tube is in the right place and we can feed. Today it read 6, which is just above that, so we are not going to feed yet. We will reposition the tube and check again, and if it is still above 5.5 we will get a quick X-ray to be certain, and then feed. This is a safety check we do before every feed, so please always ask the nurse to read out the pH number." [1] [4]

Marking domains

• Clinical reasoning (30 per cent): aspirates and reads the pH correctly; interprets a pH of 6 as above the threshold and unsafe to feed; recognises and rejects the whoosh test as a deprecated method; chooses to re-aspirate once and then escalate to radiography. [4]
• Decision-making (25 per cent): does not feed on a pH above 5.5; plans radiographic confirmation; documents the exact pH value, the method, the radiograph result, the length at the naris, and the time. [1]
• Patient safety (20 per cent): names the Never Event and the deprecated-method list; states the re-verification rule before every feed and after events that could move the tube. [9]
• Communication (15 per cent): explains to the nurse and the parent in plain language why the pH number matters, why the whoosh test is not used, and what happens next. [3]
• Follow-up (10 per cent): arranges the radiograph, confirms the result before feeding, and books the next verification. [6] [9]