Expiratory flow pattern and respiratory mechanics

1987 ◽  
Vol 65 (6) ◽  
pp. 1142-1145 ◽  
Author(s):  
Jacopo P. Mortola ◽  
Anne Marie Lauzon ◽  
Brian Mott
Keyword(s):  
Flow Pattern ◽  
Respiratory System ◽  
Airway Pressure ◽  
Work Of Breathing ◽  
Vocal Folds ◽  
Resistive Load ◽  
Adult Rats ◽  
Expiratory Flow ◽  
And Control ◽  
And Diffusion

During resting breathing, expiration is characterized by the narrowing of the vocal folds which, by increasing the expiratory resistance, raises mean lung volume and airway pressure. This is even more pronounced in the neonatal period, during which expirations with short complete airway closure are commonly occurring. We asked to which extent differences in expiratory flow pattern may modify the inspiratory impedance of the respiratory system. To this aim, newborn puppies, piglets, and adult rats were anesthetized, paralyzed, and ventilated with different expiratory patterns, (a) no expiratory load, (b) expiratory resistive load, and (c) end-inspiratory pause. The stroke volume of the ventilator and inspiratory and expiratory times were maintained constant, and the loads were adjusted in such a way that inflation always started from the resting volume of the respiratory system. After 1 min of each ventilatory pattern, mean inspiratory impedance and compliance of lung and respiratory system were measured. The values were unchanged or minimally altered by changing the type of ventilation. We conclude that the expiratory laryngeal loading is not primarily aimed to decrease the work of breathing. It is conceivable that the expiratory pattern is oriented to increase and control mean airway pressure in the regulation of pulmonary fluid reabsorption, distribution of ventilation, and diffusion of gases.

scholarly journals Control of the expiratory flow in a lung model and in healthy volunteers with an adjustable flow regulator: a combined bench and randomized crossover study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Johannes Schmidt ◽  
Anna Martin ◽  
Christin Wenzel ◽  
Jonas Weber ◽  
Steffen Wirth ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Airway Pressure ◽  
Flow Regulation ◽  
Lung Model ◽  
Resistive Load ◽  
Maximal Expiratory Flow ◽  
Medium Flow ◽  
Flow Regulator ◽  
Expiratory Flow ◽  
Spontaneously Breathing

Abstract Background Pursed-lips breathing (PLB) is a technique to attenuate small airway collapse by regulating the expiratory flow. During mandatory ventilation, flow-controlled expiration (FLEX), which mimics the expiratory flow course of PLB utilizing a digital system for measurement and control, was shown to exert lung protective effects. However, PLB requires a patient’s participation and coordinated muscular effort and FLEX requires a complex technical setup. Here, we present an adjustable flow regulator to mimic PLB and FLEX, respectively, without the need of a patient’s participation, or a complex technical device. Methods Our study consisted of two parts: First, in a lung model which was ventilated with standard settings (tidal volume 500 ml, respiratory rate 12 min−1, positive end-expiratory pressure (PEEP) 5 cmH2O), the possible reduction of the maximal expiratory flow by utilizing the flow regulator was assessed. Second, with spontaneously breathing healthy volunteers, the short-term effects of medium and strong expiratory flow reduction on airway pressure, the change of end-expiratory lung volume (EELV), and breathing discomfort was investigated. Results In the lung model experiments, expiratory flow could be reduced from − 899 ± 9 ml·s−1 down to − 328 ± 25 ml·s−1. Thereby, inspiratory variables and PEEP were unaffected. In the volunteers, the maximal expiratory flow of − 574 ± 131 ml·s−1 under baseline conditions was reduced to − 395 ± 71 ml·s−1 for medium flow regulation and to − 266 ± 58 ml·s−1 for strong flow regulation, respectively (p < 0.001). Accordingly, mean airway pressure increased from 0.6 ± 0.1 cmH2O to 2.9 ± 0.4 cmH2O with medium flow regulation and to 5.4 ± 2.4 cmH2O with strong flow regulation, respectively (p < 0.001). The EELV increased from baseline by 31 ± 458 ml for medium flow regulation and 320 ± 681 ml for strong flow regulation (p = 0.033). The participants rated breathing with the flow regulator as moderately uncomfortable, but none rated breathing with the flow regulator as intolerable. Conclusions The flow regulator represents an adjustable device for application of a self-regulated expiratory resistive load, representing an alternative for PLB and FLEX. Future applications in spontaneously breathing patients and patients with mandatory ventilation alike may reveal potential benefits. Trial registration: DRKS00015296, registered on 20th August, 2018; URL: https://www.drks.de/drks_web/setLocale_EN.do.

Respiratory mechanics in adult rats hypercapnic in the neonatal period

1990 ◽  
Vol 68 (6) ◽  
pp. 2274-2279 ◽  
Author(s):  
R. Rezzonico ◽  
R. D. Gleed ◽  
J. P. Mortola
Keyword(s):  
Mechanical Properties ◽  
Respiratory System ◽  
Neonatal Period ◽  
Statistical Significance ◽  
Lung Compliance ◽  
Long Term Effects ◽  
Adult Rats ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
And Control

Because chronic hypoxia in the neonatal period has long-term effects on the mechanical properties of the respiratory system (S. Okubo and J. P. Mortola, J. Appl. Physiol. 66: 1772-1778, 1989), we asked whether similar effects would occur after neonatal exposure to hypercapnia. Three groups of rats were used. The first was exposed to 7% CO2 in normoxia from day 1 to 7 after birth and then returned to normocapnia (NB-CO2). The second was exposed to the same level and duration of hypercapnia from day 36 to 42, i.e., approximately 2 wk after weaning (AD-CO2). The third was raised in normoxia and normocapnia (control). At approximately 50 days, i.e., 1-2 wk after puberty, the passive mechanical properties of the respiratory system, lung, and chest were measured during artificial ventilation in the anesthetized and paralyzed animal. No differences were observed between AD-CO2 and control. NB-CO2 had higher compliance of the lung (approximately +40%) and respiratory system (+32%) than control or AD-CO2. Average values of resistance of the total respiratory system, lung, and chest wall were consistently lower in NB-CO2 than in control and AD-CO2, although the magnitude and statistical significance of the decrease depended on the method of measurement. In a separate group of NB-CO2, lung compliance was measured during spontaneous breathing, and it averaged 34% more than in control. The exponential constant of the deflation quasi-static pressure-volume curve of the liquid-filled lungs was also significantly higher than in control.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamics of breathing in infants

1982 ◽  
Vol 52 (5) ◽  
pp. 1209-1215 ◽  
Author(s):  
J. P. Mortola ◽  
J. T. Fisher ◽  
B. Smith ◽  
G. Fox ◽  
S. Weeks
Keyword(s):  
Time Constant ◽  
Respiratory System ◽  
Work Of Breathing ◽  
Flow Volume ◽  
Active Compliance ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Volume Response ◽  
Residual Capacity ◽  
Expiratory Flow

Passive compliance (C) has been measured in 10 infants at 10--90 min after birth and in 10 infants at a few days of life by recording mouth pressure after airways occlusions at end inspiration. From the slope of the expiratory flow-volume curve, the passive time constant (tau) and resistance (R = tau/C) have been also computed. Examination of the changes of C with time and of the expiratory flow-volume curves indicates that the end-expiratory volume is maintained above functional residual capacity at both ages, but significantly more so at a few days (7.6 ml) than at 10--90 min (3.5 ml). The passive time constant (tau = C . R) is shorter at the early age due to the smaller C. The active compliance (C′) and resistance (R′) values have been estimated from the pressure generated by the infant when the airways are occluded at end expiration. The active time constant of the respiratory system (tau′ = C′ . R′) is less than tau, due to a smaller active compliance, particularly at a few days. The active resistance is on the contrary similar to R. The active stiffening of the respiratory system provides more stability of the infant's respiratory system and a more ready volume response for any given change in pressure; its price, however, is a higher work of breathing. At optimal breathing rates, in fact, the active work is 127% (10--90 min) to 183% (a few days) higher than that computed from the passive values. The inspiratory flow wave tends to be squared at both ages minimizing the energy losses due to friction.

Role of Rasayana in Prevention of COVID-19 - A Review

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 716-722
Author(s):  
Sneha Dhakite ◽  
Sadhana Misar Wajpeyi
Keyword(s):  
Immune System ◽  
Respiratory System ◽  
Viral Infections ◽  
Cost Effective ◽  
The Body ◽  
Healthy Life ◽  
Vital Functions ◽  
Healthy Life Style ◽  
And Control

The “Coronavirus disease 19 (COVID-19)” is caused by “Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)”, a newly discovered member of the Coronaviridae family of viruses which is a highly communicable. There is no effective medical treatment till date for Coronavirus disease hence prevention is the best way to keep disease away. Rasayana proved to be highly efficacious and cost effective for the Prevention and Control of viral infections when vaccines and standard therapies are lacking. Rasayana Chikitsa is one of the eight branches of Ashtanga Ayurveda which helps to maintain healthy life style. Rasayana improves immunity and performs many vital functions of human body. Vyadhikshamatva that is immune mechanism of the body is involved in Prevention of the occurrence of a new disease and it also decreases the virulence and progression of an existing disease. In COVID-19 the Respiratory system mainly get affected which is evident from its symptoms like cold, cough and breathlessness. Here the drugs help in enhancing immune system and strengthening functions of Respiratory system can be useful. For this purpose, the Rasayana like Chyavanprasha, Agastya Haritaki, Pippali Rasayana, Guduchi, Yashtimadhu, Haridra, Ashwagandha, Tulsi are used. Rasayana working on Respiratory system are best for Prevention of Coronavirus and boosting immune system. Rasayana Chikitsa can be effective in the Prevention as well as reducing symptoms of COVID-19.

scholarly journals Probing the Interactions of Porphyrins with Macromolecules Using NMR Spectroscopy Techniques

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1942
Author(s):  
Ilche Gjuroski ◽  
Julien Furrer ◽  
Martina Vermathen
Keyword(s):  
Nmr Spectroscopy ◽  
Photophysical Properties ◽  
Optical Methods ◽  
Spectroscopic Techniques ◽  
Control Mechanisms ◽  
Dynamic Information ◽  
Non Covalent Interactions ◽  
And Control ◽  
And Diffusion ◽  
Covalent Interactions

Porphyrinic compounds are widespread in nature and play key roles in biological processes such as oxygen transport in blood, enzymatic redox reactions or photosynthesis. In addition, both naturally derived as well as synthetic porphyrinic compounds are extensively explored for biomedical and technical applications such as photodynamic therapy (PDT) or photovoltaic systems, respectively. Their unique electronic structures and photophysical properties make this class of compounds so interesting for the multiple functions encountered. It is therefore not surprising that optical methods are typically the prevalent analytical tool applied in characterization and processes involving porphyrinic compounds. However, a wealth of complementary information can be obtained from NMR spectroscopic techniques. Based on the advantage of providing structural and dynamic information with atomic resolution simultaneously, NMR spectroscopy is a powerful method for studying molecular interactions between porphyrinic compounds and macromolecules. Such interactions are of special interest in medical applications of porphyrinic photosensitizers that are mostly combined with macromolecular carrier systems. The macromolecular surrounding typically stabilizes the encapsulated drug and may also modify its physical properties. Moreover, the interaction with macromolecular physiological components needs to be explored to understand and control mechanisms of action and therapeutic efficacy. This review focuses on such non-covalent interactions of porphyrinic drugs with synthetic polymers as well as with biomolecules such as phospholipids or proteins. A brief introduction into various NMR spectroscopic techniques is given including chemical shift perturbation methods, NOE enhancement spectroscopy, relaxation time measurements and diffusion-ordered spectroscopy. How these NMR tools are used to address porphyrin–macromolecule interactions with respect to their function in biomedical applications is the central point of the current review.

The impact of maternal protein restriction during perinatal life on the response to a septic insult in adult rats

2020 ◽  
pp. 1-8
Author(s):  
Reza Khazaee ◽  
Anastasiya Vinokurtseva ◽  
Lynda A. McCaig ◽  
Cory Yamashita ◽  
Daniel B. Hardy ◽  
...  
Keyword(s):  
Control Diet ◽  
Protein Restriction ◽  
Saline Control ◽  
Female Adult ◽  
Adult Rats ◽  
Male And Female ◽  
Maternal Protein Restriction ◽  
And Control ◽  
The Impact ◽  
Septic Insult

Abstract Although abundant evidence exists that adverse events during pregnancy lead to chronic conditions, there is limited information on the impact of acute insults such as sepsis. This study tested the hypothesis that impaired fetal development leads to altered organ responses to a septic insult in both male and female adult offspring. Fetal growth restricted (FGR) rats were generated using a maternal protein-restricted diet. Male and female FGR and control diet rats were housed until 150–160 d of age when they were exposed either a saline (control) or a fecal slurry intraperitoneal (Sepsis) injection. After 6 h, livers and lungs were analyzed for inflammation and, additionally, the amounts and function of pulmonary surfactant were measured. The results showed increases in the steady-state mRNA levels of inflammatory cytokines in the liver in response to the septic insult in both males and females; these responses were not different between FGR and control diet groups. In the lungs, cytokines were not detectable in any of the experimental groups. A significant decrease in the relative amount of surfactant was observed in male FGR offspring, but this was not observed in control males or in female animals. Overall, it is concluded that FGR induced by maternal protein restriction does not impact liver and lung inflammatory response to sepsis in either male or female adult rats. An altered septic response in male FGR offspring with respect to surfactant may imply a contribution to lung dysfunction.

scholarly journals Positive Airway Pressure Therapy Adherence with Mask Resupply: A Propensity-Matched Analysis

2021 ◽  
Vol 10 (4) ◽  
pp. 720
Author(s):  
Adam Benjafield ◽  
Liesl Oldstone ◽  
Leslee Willes ◽  
Colleen Kelly ◽  
Carlos Nunez ◽  
...  
Keyword(s):  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Group Versus ◽  
Control Group ◽  
Billing Data ◽  
Pressure Therapy ◽  
Therapy Termination ◽  
Few Data ◽  
And Control ◽  
The Impact

There are currently few data on the impact of mask resupply on longer-term adherence to positive airway pressure (PAP) therapy. This retrospective analysis investigated the effects of mask/mask cushion resupply on the adherence to PAP versus no resupply. Deidentified patient billing data for PAP supply items were merged with telemonitoring data from Cloud-connected AirSense 10/AirCurve 10 devices via AirViewTM (ResMed). Eligible patients started PAP between 1 July 2014 and 17 June 2016, had ≥360 days of PAP device data, and achieved initial U.S. Medicare adherence criteria. Patients who received a resupply of mask systems/cushions (resupply group) were propensity-score-matched with those not receiving any mask/cushion resupply (control group). A total of 100,370 patients were included. From days 91 to 360, the mean device usage was 5.6 and 4.5 h/night in the resupply and control groups, respectively (p < 0.0001). The proportion of patients with a mean device usage ≥4 h/night was significantly higher in the resupply group versus the control group (77% vs. 59%; p < 0.0001). The therapy termination rate was significantly lower in the resupply group versus the control group (14.7% vs. 31.9%; p < 0.0001); there was a trend toward lower therapy termination rates as the number of resupplies increased. The replacement of mask interface components was associated with better longer-term adherence to PAP therapy versus no resupply.

Estimation of Alveolar Pressure During Speech Using Direct Measures of Tracheal Pressure

1999 ◽  
Vol 42 (5) ◽  
pp. 1136-1147 ◽  
Author(s):  
Eileen M. Finnegan ◽  
Erich S. Luschei ◽  
Henry T. Hoffman
Keyword(s):  
Respiratory System ◽  
Airway Resistance ◽  
Sudden Change ◽  
Vocal Folds ◽  
Sentence Production ◽  
Lower Airway ◽  
Alveolar Pressure ◽  
Elastic Recoil ◽  
Pressure Source ◽  
Tracheal Pressure

The pressure in the alveoli of the lungs, created by the elastic recoil of the lungs and respiratory muscle activity, is referred to as alveolar pressure (P a ). The extent to which tracheal pressure (P t ) approximates P a depends on the resistance to airflow offered by structures above and below the point at which tracheal pressure is measured. An understanding of the relationship among P a , P t , and upper and lower airway resistance, and how these values fluctuate during speech, could aid in interpretation and modeling of speech aerodynamics. The purpose of this study was to (a) obtain values for lower airway resistance (R law ), (b) use these R law values to estimate P a during speech, and (c) quantify the degree to which P t approximates P a during production of voiced and voiceless sounds, in comparison to inhalation. In addition, the results were discussed in terms of the degree to which the respiratory system functions as a pressure source. Tracheal pressure (obtained with tracheal puncture) and airflow were measured during sentence production in 6 subjects. Using a technique introduced in this paper, R law was determined from measures of tracheal pressure and flow obtained during a sudden change in upper airway resistance because of release of a voiceless plosive. Mean R law values ranged from 0.14 to 0.32 kPa/(l/s). Each subject's mean R law was used to derive a time-varying measure of P a during speech from continuous measures of tracheal pressure and airflow. P t was approximately 95% of P a during phonation (i.e., when the vocal folds were adducted), 75% of P a during release of the voiceless stop consonant /p/, and 55% of P a during inhalation (i.e., when the vocal folds were abducted). Therefore, the degree to which the respiratory system functioned as an ideal pressure source varied during speech. The ability to estimate P a provides a measure of the pressure produced by the respiratory system that is not influenced by laryngeal activity.

Nasal CPAP and Work of Breathing Study Questioned

PEDIATRICS ◽  
1980 ◽  
Vol 65 (5) ◽  
pp. 1051-1051
Author(s):  
John Kattwinkel
Keyword(s):  
Continuous Positive Airway Pressure ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Work Of Breathing ◽  
Mechanics Of Breathing ◽  
Nasal Cpap ◽  
Sampling Catheter

The paper by Goldman et al (Pediatrics 64:160, 1979) comparing the mechanics of breathing in neonates treated with nasal vs mask continuous positive airway pressure (CPAP) recommends that, since nasal CPAP appeared to increase the work of breathing, "other methods be considered for the delivery of CDP (continuous distending pressure)." As a strong proponent of nasal CPAP, I would like to express several concerns with the study and its interpretation. First, according to the authors' drawing, the nasal device used for the study had been modified with a PE 20 sampling catheter inserted through one of the prongs.

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