Airway assessment by four-phase rhinomanometry in septal surgery.

PURPOSE OF REVIEW: This article updates the state of the art in functional ventilation tests of the nasal airway. Multidisciplinary international cooperation has led within the last years to the development of four-phase rhinomanometry (4PR) by eradicating the errors of the 'classic' rhinomanometry. RECENT FINDINGS: Physical experiments, mathematical models and comprehensive statistical analyses implicate that the nasal breath consists of four phases of different diagnostic importance. Presuming the motility of the nasal entrance, it is necessary to depict the elastic behavior within the rhinomanometric curve, as well as to use new parameters for the clinical evaluation of the nasal obstruction. The parameters logarithmic vertex resistance and logarithmic effective resistance are related to the sensing of the patient. Their clinical importance was proved in studies of more than 12 000 patients. SUMMARY: The human eye is not able to estimate the degree of impairment in nasal breathing. Therefore, a functional diagnosis is mandatory to avoid unnecessary surgery and to control the results. 4PR is a substantial improvement over the currently used methods. It should be implemented in the standards of the international standardization committee for the objective assessment of the upper airway (ISOANA). Practical hints for correct measurements are given.

Accuracy of nasal cannula pressure recordings for assessment of ventilation during sleep.

Nasal prong pressure monitoring (PNOSE) is utilized to assess ventilation during sleep. However, it has not been rigorously validated against the gold standard of face-mask pneumotachography (VFM). Therefore, we compared PNOSE with VFM in 20 patients with suspected sleep apnea during nocturnal polysomnography, and analyzed factors affecting accuracy of PNOSE-derived variables. Patients rated their nasal obstruction on a visual analog scale. Mean +/- SE apnea/hypopnea index (AHI) by VFM was 24.0 +/- 5.1 h(-1). The bias (mean difference) and limits of agreement (+/- 2 SD) of AHI derived from PNOSE, and square root-transformed PNOSE, a measure proposed as a surrogate of airflow, were +3.9 (+/- 4.6), and -0.9 (+/- 9.0) h(-1). Subjective scores of nasal obstruction before polysomnographies did not herald inaccuracy of AHI from PNOSE. Square root-transformed PNOSE closely tracked pneumotachographic airflow over 10 breaths (r(2) among signals 0.88 to 0.96) but the relationship among these signals was highly variable if comparisons were extended over an entire night. Compared with face-mask pneumotachography, nasal pressure monitoring provides accurate AHI for clinical purposes even in patients perceiving nasal obstruction. Square-root transformation provides near linear nasal pressure/airflow relationships over a short time but is not essential for estimation of AHI.