We would like to thank M. Kohler and K.E. Bloch for their interest and comments about our recent paper 1 and we appreciate the opportunity to make some remarks in reply to their letter.
Indeed, we have acknowledged that the unobtrusive instrumentation used in our study (nasal cannula/pressure transducer and oral thermistor) could not quantify ventilation 2. Nonetheless, it is considered ideal for a qualitative characterisation of sleep epochs according to the predominant signal in either the nasal or the oral channel 3, 4. Undoubtedly, the “gold standard” for quantitative monitoring of nasal or oral ventilation is a cumbersome dual compartment face mask with attached pneumotachographs 5. Additionally, the technique described by Kohler et al. 6 that quantifies overnight nasal airflow and computes side-selective nasal resistance, albeit less obtrusive than the later, still requires similar instrumentation and a rather complex calibration procedure.
We have demonstrated that nasal surgery outcome could be predicted with high sensitivity and specificity by the qualitative nasal-oral flow recordings, whereas nasal resistance measured at the beginning of the sleep study did not have any predictive value. As Kohler et al. 6 demonstrated, a single measurement does not properly reflect the highly variable values of nasal resistance during an entire night sleep. This point might be crucial for interpreting the findings of our study. Indeed, patients with fixed nasal obstruction who present predominant nasal breathing epochs during sleep may be those patients whose overnight nasal patency improves. These patients would represent the nonresponders of our study. On the contrary, patients with fixed nasal obstruction who present predominant oral or oronasal breathing epochs during sleep may be those patients whose overnight nasal patency remains unchanged or even worsens. These patients would represent the responders of our study because nasal surgery could succeed in normalising overnight nasal resistance. Nevertheless, this interesting link between the overnight variations of nasal resistance and the response to nasal surgery remains to be confirmed by future studies.
Statement of interest
None declared.
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