3.6. Auscultation versus radiological control
For all X-ray confirmed NG tubes (n = 301) the
auscultation method could be applied and compared
(see Table 2). After a loud whooshing sound, the
probability that the NG tube had been correctly placed
in the stomach was 94.7% (positive predictive value). The
probability that the absence or some degree of whooshing
sounds indicated that the NG tube had been positioned
outside the stomach (negative predictive value) was 25%.
The results of the auscultation method indicate a
sensitivity (the probability that the test correctly determines
the gastric position of the NG tube) of 79% and a
specificity (the probability that the test correctly indicates
when the NG tube is placed outside the stomach) of 61%. In
case of hearing some degree of whooshing sounds, seven
tubes were located outside the stomach.
3.7. Case examples
Two cases of misplacement in the lungs (both on the
same patient) were associated with an inconclusive
auscultation and an inability to obtain an aspirate from
the tube. The patient in question appeared perfectly lucid
and showed no signs or symptoms of respiratory distress
or coughing. Without X-ray visualisation this could
potentially have led to infusion of formula into the
patient’s lungs.
Another case involved a NG tube being placed in a
comatose patient. Upon auscultation, the assisting nurse