A modified technique for measurement of nasal transepithelial potential difference in infants

Objective: To establish a method for measuring nasal transepithelial potent ial difference (PD) in infants. Study design: A modified infant method (smaller catheter size, reduced flow rates, and shorter protocol time) was compared with an established adult n asal PD method in 10 adult volunteers (4 with cystic fibrosis [CF]). Nasal PD was measured in 13 infants with a possible diagnosis of CF. Results: Recordings were similar for the established and the modified metho ds in adult volunteers. An amiloride concentration of 10(-4) mol/L was nece ssary for full inhibition of amiloride-sensitive sodium ton (Na+) transport . Of the 13 infants, 2 had PD values suggestive of CF (mean baseline PD, -5 0.1 mV and -31.4 mV, maximum baseline PD, -61 mV and -49 mV; change in PD a fter perfusion with zero chloride solution with isoprenaline and amiloride [Delta zeroCl(-)/Iso], -1 mV and +3.5 mV), and 11 had normal values (mean S EM baseline PD, - 13.2 +/- 1.0 mV, maximum baseline PD, -21.4 +/- 2.0; Delt a zeroCl(-)/Iso, -15.3 +/- 1.9 mV). These results correlated with subsequen t sweat test data, mutation analysis, and clinical outcome. Conclusion: Nasal PD measured with this modified method is comparable to th at measured with an established adult method. The measurements were well to lerated in 13 infants and discriminated bioelectric profiles characteristic of normal and CF respiratory epithelium. This study supports the use of th is modified nasal PD technique as a diagnostic test for CF in newborn infan ts.