Noninvasive monitoring of respiratory mechanics during sleep
ABSTRACT The sleep apnoea-hypopnoea syndrome is characterised by recurrent obstructions of the upper airway, resulting in sleep disruption and arterial oxygen desaturations. Noninvasive assessment of respiratory mechanics during sleep is helpful in facilitating the diagnosis and treatment of patients with sleep apnoea-hypopnoea syndrome. This series summarises the different tools that are currently available to noninvasively assess respiratory mechanics during sleep breathing disturbances. These techniques are classified according to the main variable monitored: ventilation, breathing effort or airway obstruction. Changes in patient ventilation are assessed by recording flow or volume signals by means of pneumotachographs, thermistors or thermocouples, nasal prongs or thoraco-abdominal bands. Common tools to noninvasively assess breathing efforts are the thoraco-abdominal bands and the pulse transit time technique. Upper airway obstruction is noninvasively characterised by its upstream resistance and its critical pressure or by means of the forced oscillation technique. Given the technical and practical limitations of each technique, combining different tools improves the reliability and robustness of patient assessment during sleep.
- SourceAvailable from: Deborshi Chakraborty
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- "Additionally, there are no surface loading effects that might reduce the accuracy of the measurement. The RR is defined as the number of breaths per minute and the typical RR at resting is 12 of a healthy person with a frequency of 0.2 Hz . It has been noticed very often that there is a sudden degradation in RR leading to bradypnea (RR<12) while recovering from surgical anesthesia due to μ-opioid agonists used for pain control. "
ABSTRACT: Monitoring respiration rate in everyday life enables an early detection of the diseases and disorders that can suddenly appear as a life threatening episode. Respiratory Rate (RR) is defined as the number of breaths per minute and is a very important physiological parameter to be monitored in people both in healthy and critical condition, as it gives meaningful information regarding their respiratory system performance as well as condition. A typical RR for adult human being at rest is 12–20 and its corresponding frequency is 0.2 Hz approximately. During recovery from surgical anesthesia, a μ-opioid agonists used for pain control can slow down RR leading to bradypnea (RR < 12) or even apnea (cessation of respiration for an indeterminate period), while airway obstructions like asthma, emphysema and COPD. In all these cases long term monitoring can extend the capabilities of healthcare providers but only constraint lies with the performance reliability along with the economic barrier. In this chapter, a MEMS based capacitive nasal sensor system for measuring Respiration Rate (RR) of human being is developed. In order to develop such system, two identical arrays of diaphragms based MEMS capacitive nasal sensors are designed and virtually fabricated. A proposed schematic of the system consists of signal conditioning circuitry alongwith the sensors, is described here. In this proposed scheme, the two identical sensor arrays are mounted below Right Nostril (RN) and Left Nostril (LN), in such a way that the nasal airflow during inspiration and expiration impinge on the sensor diaphragms. Due to nasal airflow, the designed square diaphragm of the sensor is being deflected and thus induces a corresponding change in the original capacitance value. This change in capacitance value is be detected by a CMOS based clocked capacitance-to-voltage converter. The capacitive type MEMS sensors often suffer from stray and standing capacitive effect, in order to nullify this precision interface with MEMS capacitive pressure sensor, followed by an amplifier and a differential cyclic ADC is implemented to digitize the pressure information. The designed MEMS based capacitive nasal sensors is capable of identifying normal RR (18.5 ± 1.5 bpm) of human being. The design of sensors and its characteristics analysis are performed on a FEA/BEA based virtual simulation platform.Next Generation Sensors and Systems, 1 edited by Subhas Chandra Mukhopadhyay, 07/2015: chapter 7: pages 143-160; Spinger International Publisher., ISBN: 978-3-319-21670-6
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- "The methods commonly used for measuring RR are visual observation, impedance pneumography, acoustic sensing, fiber optic sensing, Respiratory Inductance Plethysmograph (RIP) and nasal prongs (NP) . However, due to very sensitive patients' movements and high cost, these methods find limited use in the clinical settings . Earlier, Siivola , Choi and Jiang  used Poly Vinyl Di Flouride (PVDF) to record respiration and cardiac action in human beings. "
ABSTRACT: In this paper, a MEMS based capacitive nasal sensor system for measuring Respiration Rate (RR) of human being is developed. At first two identical diaphragm based MEMS capacitive nasal sensors are designed and virtually fabricated. A proposed schematic of the system consists of signal conditioning circuitry alongwith the sensors is described here. In order to measure the respiration rate the sensors are mounted below Right Nostril (RN) and Left Nostril (LN), in such a way that the nasal airflow during inspiration and expiration impinge on the sensor diaphragms. Due to nasal airflow, the designed square diaphragm of the sensor is being deflected and thus induces a corresponding change in the original capacitance value. This change in capacitance value is to be detected by a correlated-double-sampling (CDS) capacitance-to-voltage converter is designed for a precision interface with a MEMS capacitive pressure sensor, followed by an amplifier and a differential cyclic ADC to digitize the pressure information. The designed MEMS based capacitive nasal sensors is capable of identifying normal RR (18.5±1.5 bpm) of human being. The design of sensors and its characteristics analysis are performed in a FEA/BEA based virtual simulation platform.International Conference on Sensing Technology 2014, Liverpool, U.K.; 09/2014
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- "However, the sensor must be placed by an expert, it is invasive and alters the patient's sleep. Instead of using Pes to score sleep apneas and hypopneas (SAHs), non-invasive Pes surrogates were studied or are still under study, such as pulse transit time (PTT) , forced oscillation technique (FOT) , , nasal airflow (NAF) – and thoraco-abdominal movements (TAM) , , . This paper proposed a novel non-invasive easy-to-use Pes surrogate, the midsagittal jaw movements, and a dedicated automatic method to score SAHs without the use of the nasal flow signal. "
ABSTRACT: Given the importance of the detection and classification of sleep apneas and hypopneas (SAHs) in the diagnosis and the characterization of the SAH syndrome, there is a need for a reliable noninvasive technique measuring respiratory effort. This paper proposes a new method for the scoring of SAHs based on the recording of the midsagittal jaw motion (MJM, mouth opening) and on a dedicated automatic analysis of this signal. Continuous wavelet transform is used to quantize respiratory effort from the jaw motion, to detect salient mandibular movements related to SAHs and to delineate events which are likely to contain the respiratory events. The classification of the delimited events is performed using multilayer perceptrons which were trained and tested on sleep data from 34 recordings. Compared with SAHs scored manually by an expert, the sensitivity and specificity of the detection were 86.1% and 87.4%, respectively. Moreover, the overall classification agreement in the recognition of obstructive, central, and mixed respiratory events between the manual and automatic scorings was 73.1%. The MJM signal is hence a reliable marker of respiratory effort and allows an accurate detection and classification of SAHs.IEEE Transactions on Biomedical Engineering 02/2008; 55(1):87-95. DOI:10.1109/TBME.2007.899351 · 2.35 Impact Factor