Analog circuit for real-time computation of respiratory mechanical impedance in sleep studies

Farré, Ramón; Rotger, M.; Montserrat, Josep M.; Navajas, Daniel

doi:10.1109/10.641343

Cited by 16 publications

(13 citation statements)

References 12 publications

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“…Although these devices have considerable facilities in the computation algorithm, their characteristics are not addressed to those applications where a simple and portable measuring system is required, such as home care and ambulatory applications. Other simpler FOT devices are based on monofrequency oscillation or on computing the amplitude of respiratory impedance [15]. Although these systems had been useful for assessing airway obstruction, particularly during sleep [16,17], they are not able to change the oscillation frequency or to apply multifrequency oscillation and their computation algorithm does not provide selective information on Rrs and Xrs.…”

Section: Discussionmentioning

confidence: 99%

A portable forced oscillation device for respiratory home monitoring

Rigau¹,

Farre²,

Roca³

et al. 2002

Eur Respir J

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The increase in the prevalence of chronic respiratory diseases has resulted in a rise in health services provided at home. The forced oscillation technique (FOT) proves to be a useful tool when it is desired to assess lung function noninvasively, and particularly for patients in whom spirometry cannot be applied. As no portable FOT device is currently available, the aim of this study was to design and test a portable FOT system for ambulatory and home care applications.The system devised is based on a microprocessor, which allows online computation of respiratory resistance (Rrs) and reactance (Xrs) and reliability indices. The portable device was compared with a conventional FOT system by using signals from 14 patients with chronic respiratory disease.This device has the same computation capabilities and flexibility as conventional FOT systems and meets the requirements for home application. Rrs (14. This portable forced oscillation technique device could be a useful tool for monitoring respiratory mechanics in ambulatory and home care applications.

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Section: Discussionmentioning

confidence: 99%

A portable forced oscillation device for respiratory home monitoring

Rigau¹,

Farre²,

Roca³

et al. 2002

Eur Respir J

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“…To further facilitate its routine applicability, both at the sleep lab and at home, the whole set-up may be optimized by employing a unique device simultaneously generating continuous positive airway pressure and oscillation [14]. Moreover, the implementation of a system for signal processing [15] and for event classi®cation could be particularly suitable for continuously auto adjusting the optimal continuous positive airway pressure.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of a simplified oscillation technique for assessing airway obstruction in sleep apnoea

Farré¹,

Rigau²,

Montserrat³

et al. 2001

Eur Respir J

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The forced oscillation technique (FOT) is a noninvasive method that is useful for assessing airway obstruction and for titrating continuous positive airway pressure (CPAP) in patients with sleep apnoea. The aim was to evaluate the routine applicability of a simpli®ed FOT set-up based on recording pressure and¯ow at the level of the CPAP device, i.e. obviating the need for connecting the transducers to the nasal mask.A correction to account for the tubing and the exhaust port was applied. This simpli®ed FOT was evaluated on nine patients with moderate or severe sleep apnoea during routine CPAP titration. Patient impedance measured by the simpli®ed FOT (|Z|) was compared with actual patient impedance (|Zrs|) measured simultaneously with a reference FOT based on recording pressure and¯ow at the nasal mask.An The sleep apnoea/hypopnoea syndrome (SAHS) is characterized by recurrent elevation of air¯ow obstruction due to total or partial collapse in the upper airway. The forced oscillation technique (FOT) is a noninvasive method particularly suitable for assessing airway impedance during application of nasal continuous positive airway pressure (CPAP) [1] and, in particular, during the apnoeas and hypopnoeas in patients with SAHS during sleep [2,3]. Recent studies have demonstrated that FOT may be a helpful tool for the diagnosis of SAHS [4] and for the titration of the level of CPAP to treat the patient [5±7].Widespread routine application of this technique in the clinical arena would be facilitated by simplifying the conventional FOT set-up used in previous studies. One possible simpli®cation of the method, which could improve patient comfort and clinical applicability, consists in recording pressure and¯ow at the inlet of the tubing connecting the CPAP device and the nasal mask. This procedure would avoid the connection of the pneumotachograph and pressure transducers to the nasal mask, which is the conventional setting [1±6]. With such a simpli®ed FOT the impedance actually measured would not be actual patient impedance but the combination of patient impedance with the impedances of the tubing and the effective impedance of the nonlinear exhaust port. Nevertheless, airway obstruction could be adequately estimated by correcting the measured impedance for the artefacts induced by the tubing and the exhaust port, as recently shown in a calibration study on mechanical analogues [8]. The aim of the present work was to determine whether this simpli®ed FOT approach is easily applicable and reliable for measuring airway obstruction in routine sleep studies. To this end, the simpli®ed FOT was evaluated when routinely applied in nine patients with SAHS during sleep. The results obtained with this simpli®ed FOT approach were compared with those simultaneously obtained with a reference FOT setting based on recording pressure and¯ow at the nasal mask. Methods PatientsThe study was carried out on nine patients with a diagnosis of moderate or severe SAHS documented by polysomnography. The patients had not been previousl...

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“…A low-power, low-frequency rectifier would be one of the constituent building blocks to implement the proposed algorithm. Other examples of systems that when developed will benefit from low-power rectifier blocks include portable surface electromyography systems and systems for sleep studies and treatment of obstructive sleep apnoea [7,8].…”

Section: Introductionmentioning

confidence: 99%