Nasal pd in cystic fibrosis

Nasal PD profile from a CF subject		home

The baseline PD is high (at around -50mV) and the subsequent response to amiloride is large (perfusion started at point a, nearly 30 mV). The response to perfusion with a solution low in chloride ions (point b)is small and demonstrates the "falling away" that is characteristic of CF. The final perfusion change is the addition of ATP (point c). In CF this generally (although not always) leads to a large response, which after an initial peak falls away. Many have advocated adding ATP (or another purine) at the end of the PD measurement as an indicator of epithelial integrity. For example, the finding of a normal or low baseline and a small response to a low chloride solution may be related to epithelial inflammation (for example, if the subject has a cold). However, if there is a subsequent large response to perfusion with ATP this would argue against that and make the result more worrying