Sensitivity and specificity of hypopnoea detection using nasal pressure in the presence of a nasal expiratory resistive device (Provent^®)

Abstract

Nasal expiratory resistive valves (Provent(®)) have been proposed as novel therapy for obstructive sleep apnea. We compared pressure measurements from a standard nasal pressure catheter used to assess nasal airflow during sleep with those from nasal expiratory resistive device with attached proprietary nasal pressure cannula. Nasal pressure cannula or Provent(®) + proprietary nasal pressure cannula were attached to a bench model of human anterior nares and nasal passages, and pressure measured (P). Respiratory airflows generated by a subject breathing were applied to rear of model and airflow (V) measured via pneumotachograph. Airflow amplitude (ΔV) was plotted against pressure amplitude (ΔP). Hypopnoea detection (<50% ΔV) sensitivity and specificity was tested by expressing ΔP in terms of two reference breaths: reference breath 1, ΔV 0.55 L s(-1) = 100%; and reference breath 2, ΔV 0.45 L s(-1) = 100%. ΔP/ΔV relationships were linear for ΔV ≤ 0.55 L s(-1); ΔP = 0.37ΔV + 0.16 (nasal pressure cannula), ΔP = 2.7ΔV + 0.12 (Provent(®) + proprietary nasal pressure cannula); both R(2) > 0.65, p < 0.0001; p < 0.0001 for between slope difference). For nasal pressure cannula, specificity of hypopnoea detection differed between reference breaths one and two (80.2% and 40.0%, respectively), and Provent(®) + proprietary nasal pressure cannula (30.3% and 74.2%, respectively). Quantification of airflow obstruction in the presence of Provent(®) + proprietary nasal pressure cannula is greatly influenced by the reference breath chosen to determine a reduction in nasal airflow. Reported variability in therapeutic response to nasal expiratory resistive devices may relate to differences in measurement technique specificity used to quantify the severity of sleep disordered breathing.

Expiratory Positive Airway Pressure for Sleep Apnea after Stroke: A Randomized, Crossover Trial

“…Other possible explanations for this negative result include (1) underestimation of treatment effect due to possible inadequate EPAP use, though sensitivity analysis that excluded those with poorer self-reported use showed similar results, and (2) overestimation of treatment effect in prior studies due to inaccurate measurement of AHI. 17 The current study is unique among EPAP trials in that it assessed OSA without introducing possible measurement error from a nasal pressure cannula inserted through the EPAP device. 17 With respect to tolerability, most patients reported nasal EPAP use for greater than 3 h during the intervention night.…”

“…17 The current study is unique among EPAP trials in that it assessed OSA without introducing possible measurement error from a nasal pressure cannula inserted through the EPAP device. 17 With respect to tolerability, most patients reported nasal EPAP use for greater than 3 h during the intervention night. Furthermore, sleep efficiency was similar on the EPAP and no EPAP nights, even in those with EPAP use ≥ 3 h per night, which suggests that EPAP use did not substantially interfere with sleep.…”

“…The Watch-PAT was particularly well suited for this research because it does not require a nasal pressure or airflow sensor, which may be ineffective during use of EPAP. 17 Patients were determined to have OSA if they had an AHI ≥ 5 on either the treatment night or the control night. Only data obtained during sleep time, based on Watch-PAT actigraphy data, were included in AHI calculations.…”