Testing limits to airflow perturbation device (APD) measurements

<p>Abstract</p> <p>Background</p> <p>The Airflow Perturbation Device (APD) is a lightweight, portable device that can be used to measure total respiratory resistance as well as inhalation and exhalation resistances. There is a need to determine limits to the accuracy of APD measurements for different conditions likely to occur: leaks around the mouthpiece, use of an oronasal mask, and the addition of resistance in the respiratory system. Also, there is a need for resistance measurements in patients who are ventilated.</p> <p>Method</p> <p>Ten subjects between the ages of 18 and 35 were tested for each station in the experiment. The first station involved testing the effects of leaks of known sizes on APD measurements. The second station tested the use of an oronasal mask used in conjunction with the APD during nose and mouth breathing. The third station tested the effects of two different resistances added in series with the APD mouthpiece. The fourth station tested the usage of a flexible ventilator tube in conjunction with the APD.</p> <p>Results</p> <p>All leaks reduced APD resistance measurement values. Leaks represented by two 3.2 mm diameter tubes reduced measured resistance by about 10% (4.2 cmH₂O·sec/L for control and 3.9 cm H₂O·sec/L for the leak). This was not statistically significant. Larger leaks given by 4.8 and 6.4 mm tubes reduced measurements significantly (3.4 and 3.0 cm cmH₂O·sec/L, respectively). Mouth resistance measured with a cardboard mouthpiece gave an APD measurement of 4.2 cm H₂O·sec/L and mouth resistance measured with an oronasal mask was 4.5 cm H₂O·sec/L; the two were not significantly different. Nose resistance measured with the oronasal mask was 7.6 cm H₂O·sec/L. Adding airflow resistances of 1.12 and 2.10 cm H₂O·sec/L to the breathing circuit between the mouth and APD yielded respiratory resistance values higher than the control by 0.7 and 2.0 cm H₂O·sec/L. Although breathing through a 52 cm length of flexible ventilator tubing reduced the APD measurement from 4.0 cm H₂O·sec/L for the control to 3.6 cm H₂O·sec/L for the tube, the difference was not statistically significant.</p> <p>Conclusion</p> <p>The APD can be adapted for use in ventilated, unconscious, and uncooperative patients with use of a ventilator tube and an oronasal mask without significantly affecting measurements. Adding a resistance in series with the APD mouthpiece has an additive effect on resistance measurements, and can be used for qualitative calibration. A leak size of at least the equivalent of two 3.2 mm diameter tubes can be tolerated without significantly affecting APD measurements.</p

Telemonitoring systems for respiratory patients: technological aspects.

Abstract This review introduces the reader to the available technologies in the field of telemonitoring, with focus on respiratory patients. In the materials and methods section, a general structure of telemonitoring systems for respiratory patients is presented and the sensors of interest are illustrated, i.e., respiratory monitors (wearable and non-wearable), activity trackers, pulse oximeters, environmental monitors and other sensors of physiological variables. Afterwards, the most common communication protocols are briefly introduced. In the results section, selected clinical studies that prove the significance of the presented parameters in chronic respiratory diseases are presented. This is followed by a discussion on the main current issues in telemedicine, in particular legal aspects, data privacy and benefits both in economic and health terms

Effect of portable non-invasive ventilation on exercise tolerance in COPD: One size does not fit all

In a cross-over RCT, portable NIV (pNIV) reduced dynamic hyperinflation (DH) compared to pursed lip breathing (PLB) during recovery from intermittent exercise in COPD, but not consistently in all subjects. In this post-hoc analysis, DH response was defined as a reduction ≥4.5 % of predicted resting inspiratory capacity with pNIV compared to PLB. At exercise iso-time (where work completed was consistent between pNIV and PLB), 8/24 patients were DH non-responders (DH: 240 ± 40 mL, p = 0.001 greater using pNIV). 16/24 were DH responders (DH: 220 ± 50 mL, p = 0.001 lower using pNIV). Compared to DH responders, DH non-responders exhibited greater resting DH (RV/TLC: 65 ± 4% versus 56 ± 2%; p = 0.028) and did not improve exercise tolerance (pNIV: 30.9 ± 3.4 versus PLB: 29.9 ± 3.3 min; p = 0.603). DH responders increased exercise tolerance (pNIV: 34.9 ± 2.4 versus PLB: 27.1 ± 2.3 min; p = 0.001). Resting RV/TLC% was negatively associated with the magnitude of DH when using pNIV compared to PLB (r=-0.42; p = 0.043). Patients with profound DH were less likely to improve exercise tolerance with pNIV. Further studies using auto-adjusted ventilators are warranted

Effect of acute and chronic pressure-threshold inspiratory muscle training on upper and lower airway function

There is evidence to suggest that inspiratory muscle training (IMT) may influence the functional properties of the muscles of the upper (UA) and lower (LA) airway. However, the nature and functional relevance of this influence is currently unclear. This thesis examined the effect of acute and chronic IMT in the context of UA and LA function. The ability of IMT to activate the UA dilator muscles, genioglossus (GG) and geniohyoid (GH), was examined using magnetic resonance imaging (MRI), as was the effect of chronic training on these muscles. In addition, the effect of acute and chronic IMT upon LA resistance (Rrs) and function was investigated in people with asthma using the Forced Oscillation Technique and conventional spirometry. For the UA, an acute bout of IMT at 60% maximal inspiratory mouth pressure (MIP) resulted in significant GG and GH activation (P < 0.001) as demonstrated by increases in the transverse relaxation time of muscle water (T2). Despite this, MRI was unable to detect any effect of chronic IMT upon UA function. For the LA, the usual increase in Rrs, following deep inhalation (DI) in people with asthma was attenuated with both single and multiple breaths against a pressure-threshold load equal to 50% MIP. However, six weeks IMT had no effect on baseline airway function or response to DI. In conclusion, an acute effect of pressure-threshold IMT upon UA and LA function was demonstrated. A strong rationale for a beneficial influence of chronic pressure-threshold IMT was therefore demonstrated. However, the data were insufficient to either reject, or accept the hypothesis that IMT exerts more than a transient influence upon UA and LA function, but insights are presented that support the need for further investigations.EThOS - Electronic Theses Online ServiceHarry BrarHaB International LtdGBUnited Kingdo

Keuhkoputkien supistumisherkkyys ja hengitystieinflammaatio pienillä, hengitystieoireisilla lapsilla

Background: The diagnosis of asthma in young children is based mostly on symptoms. The need for objective methods for diagnosing asthma in this age group is therefore obvious. Lung function in preschool children can be assessed with impulse oscillometry (IOS), which involves no voluntary breathing manoeuvers. Because most children with asthma have normal baseline lung function, the use of bronchoprovocative tests may improve diagnostics. Fractional concentration of nitric oxide (FeNO) is suggested to be a good measure for airway inflammation, and the method is also available for preschoolers. Aims: To examine new methods for evaluating airway hyperresresponsiveness and inflammation in young children. Further aims were to study the effect of parental smoking on lung function and airway inflammation in wheezy children and whether children with severe exercise induced bronchoconstriction exhibit small airways dysfunction. Methods: A total of 272 children (3 to 8 years old), 231 with obstructive syndromes and 41 healthy controls, were examined. Children with various clinical characteristics were recruited: troublesome lung symptoms, a history of bronchopulmonary dysplasia (BPD), early wheezing symptoms and multiple-trigger wheezing. Airway hyperresponsiveness was evaluated with exercise test, methacholine and mannitol challenge tests using IOS. FeNO measurements with two different analyzers were examined. Parental reports and children s urinary cotinine measurements served to monitor exposure to environmental tobacco smoke. Results: Exercise test with IOS succesfully identified children with probable asthma, and the methacholine challenge test was able to differentiate children with probable asthma, BPD and early wheezing from the controls. The mannitol challenge test, however, was unable to distinguish between the study groups. Furthermore, children with severe exercise-induced bronchoconstriction (EIB) exhibited small airways dysfunction. A portable FeNO analyzer proved to be more difficult than a stationary device to use in young children. In addition, its poorer accuracy in low FeNO levels diminishes its feasibility in this age group. However, a portable analyzer differentiated children with asthma from the controls. Children with smoking mothers had poorer lung function and higher FeNO than children with non-smoking mothers. Urinary cotinine concentrations closely reflected reported smoking in the family. A father s smoking had no effect on children s FeNO or lung function. Conclusions: The exercise test with IOS succesfully identified children with probable asthma. The methacholine challenge test aids in evaluating airway hyperresponsiveness in young children, although its cut-off value for this age group requires re-evaluation. A portable FeNO analyzer can also serve as a screening tool in young children, because it differentiates asthmatics from the controls with reasonable accuracy. Children with severe exercise induced bronchoconstriction exhibited small airways dysfunction, which suggests that peripheral airways are involved even in young asthmatic children. Maternal smoking clearly deteriorates lung function and increases bronchial inflammation in young children with wheeze. This objective finding with cotinine measurements emphasizes current knowledge; young children should not be exposed to environmental tobacco smoke.Tausta: Pienillä lapsilla on paljon hengitystieoireita. Hengitysoireiden selvittely ja astmadiagnostiikka tässä ikäryhmässä perustuu enimmäkseen oireiden tulkintaan ja riskitekijöiden kartoitukseen. Leikki-ikäisen lapsen keuhkojen toimintaa voidaan tutkia oskillometrialla, joka ei vaadi lapselta suurta yhteistyökykyä. Valtaosalla astmaa sairastavista lapsista on normaali keuhkojen toiminta perustilassa, jolloin diagnostiikka voi täsmentyä keuhkoputkien supistumistaipumuksen määrityksellä. Uloshengityksen typpioksidipitoisuutta mittaamalla voidaan arvioida keuhkoputkien astmaattista tulehdusta. Erilaiset ärsykkeet, kuten tupakansavulle altistuminen, voivat vaikuttaa lapsen hengitysteiden astmaattiseen tulehdukseen ja keuhkojen toimintaan. Tavoitteet: Selvittää uusien menetelmien toimivuutta leikki-ikäisen lapsen keuhkoputkien supistumisherkkyyden ja astmaattisen tulehduksen arvioinnissa. Lisäksi tavoitteena oli tutkia vanhempien tupakoinnin vaikutusta lapsen keuhkojen toimintaan. Menetelmät: Tutkimukseen osallistui 272 (3-8-vuotiasta) lasta, joista 231 oli hengitystieoireisia ja 41 terveitä verrokkeja. Tutkimukseen osallistui astmaepäilyn vuoksi selvityksiin lähetettyjä, vastasyntyneenä bronkopulmonaalisen dysplasian (keskosen keuhkosairaus) sairastaneita sekä alle 2-vuotiaana toistuvista hengitysvaikeuksista kärsineitä lapsia. Keuhkoputkien supistumistaipumusta tutkittiiin ulkojuoksukokeella sekä metakoliini- ja mannitolialtistustestillä. Keuhkojen toiminta määritettiiin oskillometrialla. Keuhkoputkien astmaattista tulehdusta arvioitiin uloshengityksen tyypioksidipitoisuutta mittaamalla kahdella eri laitteella. Tupakansavulle altistumista monitoroitiin vanhempien täyttämällä kyselykaavakkeella sekä lasten virtsan kotiniinimäärityksellä. Tulokset: Ulkojuoksukoe oskillometriaseurannassa erotteli hyvin astmaoireista kärsineet lapset muista ryhmistä. Metakoliinialtistustesti osoitti keuhkoputkien supistumista kahdella kolmasosalla kaikista tutkituista lapsista, mutta hengitysoireista kärsineet lapset olivat sille herkempiä kuin kontrollilapset. Mannitolialtistustesti ei erotellut ryhmiä toisistaan. Lapsilla, joilla oli vaikein rasituksen aiheuttama keuhkoputkien supistumistaipumus, oli myös poikkeavuutta pienten ilmateiden toiminnassa. Uloshengityksen typpioksidin mittaaminen on vaikempaa kannettavalla mittarilla kuin isommalla laitteella, ja myös laitteen huonompi tarkkuus matalilla pitoisuuksilla rajoittaa sen käyttöä pienillä lapsilla. Tupakoivien äitien lapsilla oli huonompi keuhkojen toiminta ja enemmän keuhkoputkien astmaattista tulehdusta kuin tupakoimattomien äitien lapsilla. Isien tupakoinnilla ei ollut samanlaista vaikutusta lasten keuhkojen toimintaan. Virtsan kotiniinipitoisuudet kuvasivat hyvin vanhempien ilmoittamaa tupakointia kotona. Johtopäätökset: Ulkojuoksukoe yhdistetty oskillometriatutkimukseen on hyvä tutkimus leikki-ikäisen astmaoireiden selvittelyssä. Metakoliinialtistus on tämän tutkimuksen mukaan toimiva menetelmä keuhkoputkien supistumistaipumuksen selvittelyssä, mutta pienten lasten viitearvojen puuttuminen rajoittaa sen käyttöä tässä ikäryhmässä. Kannettavaa uloshengityksen typpioksidimittaria voidaan käyttää seulontamielessä myös pienillä lapsilla. Äitien tupakointi huonontaa astmaoireista kärsivien lasten keuhkojen toimintaa ja lisää keuhkoputkien astmaattista tulehdusta. Tämä objektiivinen löydös vahvistaa käsitystä, että pienen lapsen ei tulisi altistua tupakansavulle