Assessment of three methods of pH probe positioning in preterm infants.
BACKGROUND
In the assessment of gastroesophageal reflux, correct placement of the pH catheter is crucial. This is particularly so in very low birth weight infants where a small error in positioning could give rise to a potentially large error in results. Accepted modes of assessing correct positioning can be problematic in this population of infants and alternative methods were investigated.


METHODS
A total of 26 preterm infants (<35 weeks gestation) were enrolled in this study. All infants were suspected of having GOR and pH monitoring was performed. Probe position was assessed using Strobel's formula, manometry and acid-alkali interface and confirmed by chest x-ray.


RESULTS
There was a highly significant positive correlation between the calculation of the pH probe position using Strobel's formula and the position on x-ray and a significant positive correlation between the acid/alkali interface and x-ray position. There was no correlation between manometry and x-ray position and this method was also shown to be problematic in its' application.


CONCLUSIONS
The data suggests that it is appropriate to use Strobel's formula as a method of accurate positioning of pH probes in preterm infants, thus avoiding the need for additional x-rays. The acid/alkali interface, when obtainable, is a secondary, satisfactory method to confirm the position calculated by Strobel's formula.
Emmerson
Anthony J B
AJ
Neonatal Medical Unit, St. Mary's Hospital, Whitworth Park, Manchester, UK. anthony.mmerson@man.ac.uk
Chant
Terri
T
May
Judith
J
Vales
Patricia
P
D001827:Body Height; D004947:Esophagus / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005764:Gastroesophageal Reflux / Q000175:diagnosis*; D005865:Gestational Age; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008365:Manometry; D008433:Mathematics; D011859:Radiography