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Dear colleagues Some nursing colleagues who I have been working with on improving our EBP skills came up with the following EBP question. In patients who are being fed by NG tube how good is pH testing at determining whether the tube is in the Stomach or in the lungs ? Practice at the hospital where they work is currently that the position of all tubes when inserted is checked by a pH test and also by X-Ray before feeding is commenced. They came up with the following observations about this: 1) It seems strange to bother with the ph test if you are going to x-ray the patient anyway. 2) Patients often pull on the tubes or the tubes get pulled and therefore moved and often nurses just push the tube back and do a ph test only. 3) If everytime patients pull on tube need to get it re x-rayed this will results in patients having a lot of x-rays, and will be quite expensive 4) Doing a only a pH test on insertion if sensitive enough would reduce patient exposure to radiation and save a considerable amount of resources My recommendation to them (I hope its the correct one ) was that they should treat this as a diagnostic test question. The evidence they would need to find would therefore be a study whereby a group of patients with ng tubes had the position checked by ph testing (by your average nurse in real clinical setting (usually visual reading of test reagent stick)) and by the gold standard (x-ray) and then the sensivity and specificity, Pos predictive value etc. etc. for ph testing could be established They have been searching for this kind of study and no luck yet (have found a lot of work by Norma Metheny and Colleagues from St louis University which we are ploughing through but does not seem to answer this particular question ) q.1 if anybody else knows of any other evidence sources for this would be grateful to hear about them reading so far has thrown up lots of questions about the various methods of ph testing. Currently in this hospital they are using litmus paper - Some of the evidence we have found on this suggests that litmus paper is not good at discriminating between gastric fluid and lung fluid because it can change colour for both because of ph level at which it is sensitive (sorry can't remember what this is at the moment) But evidence is not that good quality q2. Anybody know of any other evidence on this I have technical question about such a study. The risk of the tube being in the lungs undetected appears to be quite small (4/605 in one study). It would also be unethical if not impossible in practice do a study where tubes were deliberately put into the lung as well as put into the stomach. q3. If in a study all the tests were on ph testing where all the tubes were in the stomach would this answer our question - if not what else could researchers do? The risk of the tube being in the lungs undetected appears to be quite small, However in the literature it seems to be regarded as absolutely imperative that this is established before the feeding started due to what are described as the grave consequences of starting feeding with the tube incorrectly positioned. q4. Does this mean that only a test which is 100% sensitive (or whatever current gold standard level is - presumably x-ray is very near this) is acceptable ? That will give you something to chew during the festive season. Look forward to hearing your replies which I will summarize for list. seasons greetings mark ***PLEASE NOTE ARCHWAY PHONE NUMBER CHANGED AGAIN***** Mark Newman Senior Lecturer: School of Health, Biological & Environmental Sciences (HeBES) Middlesex University & Barnet & Chase Farm Hospitals NHS Trust Furnival Building, Archway Campus Highgate Hill London N19 3UA Tel: 0181 362 5000 (ex2281) or 0181 366 6600 ex 5775 Fax: 0181 362 6299 E-Mail: [log in to unmask] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%