Respiratory Resistive Impedance as an Index of Airway Obstruction during Nasal Continuous Positive Airway Pressure Titration

A bench study using an artificial lung model was performed to evaluate the snoring detection sensitivity of six (commercially available) auto-nasal continuous positive airway pressure (NCPAP) devices.Snoring was simulated by a loudspeaker connected to the lung model and abruptly activated during 1 s of each inspiratory period to induce pressure oscillation. The oscillation frequencies chosen were 30, 60, 90, and 120 Hz. For each frequency, the amplitude of the pressure oscillation produced by the loudspeaker was adjusted to find the threshold at which the auto-nCPAP devices detected snoring.Differences in pressure-amplitude thresholds of up to three-fold were found across auto-nCPAP devices. A randomized clinical study to compare the effects of the least sensitive (Virtuoso LX; Respironics, Nantes, France) and one of the most sensitive, (Goodknight 418A; Malinckrodt, Nancy, France) devices, in two groups of six patients with obstructive sleep apnoea syndrome was then conducted. Goodknight 418A was more sensitive than Virtuoso LX for detecting snoring (mean¡SD 92¡11% versus 50¡39% respectively, p=0.03).To conclude, striking differences exist between auto-nasal continuous positive airway pressure devices in sensitivity for detecting snoring.

Section: Discussionmentioning

confidence: 99%

Snoring detection during auto-nasal continuous positive airway pressure

Lofaso

Leroux²,

Quera-Salva³

et al. 2002

“…Monitoring of Zrs may be a useful complementary tool in the adaptation of ventilator settings during invasive and noninvasive ventilation [130][131][132][133][134][135]. The FOT has also been used to improve the diagnosis of sleep disturbances [136] and to determine the optimal continuous positive airway pressure (CPAP) level required to treat obstructive sleep apnoea [137][138][139][140]. In sleep studies, changes of Zrs along the breathing cycle are followed, since obstructive sleep apnoeas/hypopnoeas are characterised by marked changes within the breathing cycle [138].…”

Section: Applications Of Forced Oscillation Technique In Monitoring Rmentioning

confidence: 99%

The forced oscillation technique in clinical practice: methodology, recommendations and future developments

Oostveen¹,

MacLeod²,

Lorino³

et al. 2003

1,105

1,120

The forced oscillation technique (FOT) is a noninvasive method with which to measure respiratory mechanics. FOT employs small-amplitude pressure oscillations superimposed on the normal breathing and therefore has the advantage over conventional lung function techniques that it does not require the performance of respiratory manoeuvres.The present European Respiratory Society Task Force Report describes the basic principle of the technique and gives guidelines for the application and interpretation of FOT as a routine lung function test in the clinical setting, for both adult and paediatric populations.FOT data, especially those measured at the lower frequencies, are sensitive to airway obstruction, but do not discriminate between obstructive and restrictive lung disorders. There is no consensus regarding the sensitivity of FOT for bronchodilation testing in adults. Values of respiratory resistance have proved sensitive to bronchodilation in children, although the reported cutoff levels remain to be confirmed in future studies.Forced oscillation technique is a reliable method in the assessment of bronchial hyperresponsiveness in adults and children. Moreover, in contrast with spirometry where a deep inspiration is needed, forced oscillation technique does not modify the airway smooth muscle tone. Forced oscillation technique has been shown to be as sensitive as spirometry in detecting impairments of lung function due to smoking or exposure to occupational hazards. Together with the minimal requirement for the subject9s cooperation, this makes forced oscillation technique an ideal lung function test for epidemiological and field studies. Novel applications of forced oscillation technique in the clinical setting include the monitoring of respiratory mechanics during mechanical ventilation and sleep.

“…It has been observed that the nonlinear characteristics of the transnasal pressure-flow relationship, which are pronounced at 1±2 Hz, diminish as the frequency increases [13]. It has also been shown that nasal resistance can be assessed by forced oscillation [14], and that respiratory resistance, measured at the nose during continuous positive airway pressure titration, reflects lung resistance determined from transpulmonary pressure [15].…”

Section: Discussionmentioning

confidence: 99%

Effects of mandibular advancement on respiratory resistance

Lorino¹,

Maza²,

d’Ortho³

et al. 2000

Mandibular advancing devices are proposed as nonsurgical treatment for certain patients with an obstructive sleep apnoea syndrome. Since they act by increasing the upper airway calibre, the aim of the present study was to investigate the changes in respiratory resistance (Rrs) resulting from mandibular advancement.Rrs was measured at the nose by the forced oscillation technique (4±32 Hz). Ten normal subjects were studied under three conditions: resting mandibular position, passive mandibular advancement steadied by a wax bite, and voluntary advancement, in random order. Respiratory resistance was extrapolated to 0 Hz (R0) and estimated at 16 Hz (R16) by linear regression analysis of respiratory resistive impedance versus frequency.R0 ( The results of this study demonstrate that the effects of mandibular advancement on upper airway resistance differ, depending on whether advancement is passive or active, and suggest that in order to simulate the actual effects of therapeutic devices, mandibular advancement should be passive. Eur Respir J 2000; 16: 928±932.