Spirometry provides objective information about pulmonary function and assesses the results of therapy. Pulmonary function testes early in the course of COPD reveal only evidence of dysfunction in small airways. Reduction in forced expiratory volume in 1 second (FEV1) and in the ratio of forced expiratory volume to forced vital capacity (FEV1, FVC) occurs later. In severe disease, the forced vital capacity is markedly reduced. Lung volume measurements revealed increase in the total lung capacity (TLC), marked increase in the residual volume (VR), and elevation of the VR/TLC ratio, indicative of air trapping, particularly in emphysema
Emphysema ; diagnosis ; physiology ; Pulmonary Ventilation ; asthma

It is difficult to select the appropriate ventilation mode in clinical mechanical ventilation. This paper presents a nonlinear multi-compartment lung model to solve the difficulty. The purpose is to optimize respiratory airflow patterns and get the minimum of the work of inspiratory phrase and lung volume acceleration, minimum of the elastic potential energy and rapidity of airflow rate changes of expiratory phrase. Sigmoidal function is used to smooth the respiratory function of nonlinear equations. The equations are established to solve nonlinear boundary conditions BVP, and finally the problem was solved with gradient descent method. Experimental results showed that lung volume and the rate of airflow after optimization had good sensitivity and convergence speed. The results provide a theoretical basis for the development of multivariable controller monitoring critically ill mechanically ventilated patients.
Exhalation ; Humans ; Lung ; physiology ; Models, Biological ; Nonlinear Dynamics ; Pulmonary Ventilation ; Respiration ; Respiration, Artificial ; Tidal Volume

At present, the passive simulated lung including the splint lung is an important device for hospitals and manufacturers in testing the functions of a respirator. However, the human respiration simulated by this passive simulated lung is quite different from the actual respiration. And it is not able to simulate the spontaneous breathing. Therefore, including" the device simulating respiratory muscle work "," the simulated thorax" and" the simulated airway", an active mechanical lung to simulate human pulmonary ventilation was designed:3D printed human respiratory tract was developed and connected the left and right air bags at the end of the respiratory tract to simulate the left and right lungs of the human body. By controlling a motor running to drive the crank and rod to move a piston back and forth, and to deliver an alternating pressure in the simulated pleural, and so as to generate an active respiratory airflow in airway. The experimental respiratory airflow and pressure from the active mechanical lung developed in this study are consistent with the target airflow and pressure which collected from the normal adult. The developed active mechanical lung function will be conducive to improve the quality of the respirator.
Adult ; Humans ; Lung/physiology* ; Respiration ; Pulmonary Ventilation ; Respiration, Artificial ; Ventilators, Mechanical

Traditionally, adequate tidal volume is considered to be a necessary condition to support respiratory patient breathing. But the high frequency ventilation (HFV) with a small tidal volume can still support the respiratory patient breathing well. In order to further explore the mechanisms of HFV, the pendelluft ventilation between left and right lungs was proposed in this paper. And a test platform by using two fresh sheep lungs was developed for investigating the pendelluft ventilation between the left and right lungs. Furthermore, considering the viscous resistance ( ), inertance ( ) and lung compliance ( ) in the lung, a second-order lung ventilation model was designed to inspect and evaluate the pendelluft ventilation between left lung and right lungs. On referring to both results of experiments in practice and simulation in MATLAB Simulink, between the left and right lungs, the phase difference in their airflow happens during HFV at some frequencies. And the pendelluft ventilation between the left and right lungs is resulted by the phase difference, even if the total airflow entering a whole lung is 0. Under HFV, the pendelluft ventilation between left and right lungs will benefit the lungs being more adequately ventilated, and will be improve the utilization rate of oxygen in the lungs.
Animals ; High-Frequency Ventilation ; Humans ; Lung ; physiology ; Pulmonary Gas Exchange ; Respiration, Artificial ; Sheep ; Tidal Volume

OBJECTIVETo investigate the effect of non-invasive positive pressure ventilation (NIPPV) on the work of breathing (WOB) in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD).

METHODSEleven patients with acute exacerbation of COPD received pressure support ventilation (PSV) at different levels during NIPPV. The changes of inspiratory muscle effort and breathing pattern of the patients were observed.

RESULTSThe average minute ventilation (VE, P<0.01) and tidal volume (VT, P<0.05) of the patients were significantly higher during routine PSV and high pressure support (H-PS) than those during spontaneous breathing (SB), and the breathing pattern of the patients did not undergo significant changes during high positive end expiratory pressure (H-PEEP). The WOB of the inspiratory muscles was reduced significantly during PSV as compared with that measured in SB (P<0.01), while the WOB of exspiratory muscle increased significantly (P<0.01).

CONCLUSIONNIPPV can relieve the load of the inspiratory muscles in patients with acute exacerbation of COPD, and the WOB of the inspiratory muscles can be reduced by PSV, H-PEEP and H-PS (by 75%, 71% and 76%, respectively), but higher PSV during NIPPV can cause higher WOB of the exspiratory muscles.

Aged ; Exhalation ; physiology ; Humans ; Inhalation ; physiology ; Male ; Middle Aged ; Pressure ; Pulmonary Disease, Chronic Obstructive ; pathology ; physiopathology ; therapy ; Pulmonary Ventilation ; Work of Breathing ; physiology

Ouabain, a Na(+)/K(+)-ATPase inhibitor, induces slowly adapting pulmonary stretch receptors (SARs) to discharge paradoxically. Paradoxical discharge is characterized by increased SAR activity during lung deflation coupled with silence during lung inflation. We hypothesized that over-excitation silences the SARs. Accordingly, if cyclic inflation pressure was reduced so as to lower SAR stimulation, paradoxical discharge would be prevented. In the present study, single-unit activity of SARs was recorded in anesthetized, open-chest and mechanically ventilated rabbits with positive-end-expiratory pressure (PEEP). After microinjection of ouabain into the receptive field, SAR activity initially increased and then gradually became paradoxical. During paradoxical cycling, SAR activity started and stopped abruptly, oscillating between high frequency discharge during lung deflation and silence during peak inflation. Removing PEEP reduced basal cyclic stimulation and returned the discharge pattern to normal, that is, SAR activity was highest at peak inflation pressure but silent during deflation. It is speculated that stretching SARs causes Na(+) influx, producing generator potential (GP). Normally, GP recovers by Na(+) extrusion via Na(+)/K(+)-ATPase. Ouabain inhibits the ATPase, which limits Na(+) extrusion, and thus sustains the GP. Therefore, after ouabain microinjection, lung inflation will further increase GP, causing over-excitation to silence the SARs.
Action Potentials ; physiology ; Adaptation, Physiological ; drug effects ; Animals ; Lung ; drug effects ; physiology ; Male ; Mechanoreceptors ; physiology ; Ouabain ; pharmacology ; Pulmonary Stretch Receptors ; drug effects ; physiology ; Pulmonary Ventilation ; drug effects ; physiology ; Rabbits ; Sodium-Potassium-Exchanging ATPase ; antagonists & inhibitors ; physiology ; Vagus Nerve ; physiology

The research on cycle change form of the pressure and the wall shear in human upper respiratory tract can strengthen understanding of the characteristics of the airflow in the place and provide us with a scientific basis for analyzing the diffusion, transition and deposition patterns of aerosol there. In our study, we used large eddy simulation to emulate the pressure and wall shear in human upper respiratory tract in conditions of the low intensive respiratory patterns, and discussed the distributing disciplinarian of the pressure and wall shear in mouth-throat model and trachea-triple bifurcation. The results showed that the pressure gradient variation in human upper respiratory tract was mainly fastened from root of epiglottis to trachea. The minimum pressure at the interim of inspiration was a duplication of the interim of expiration, and located on the posterior wall of the glottis. The pressure gradient variation was evident on trachea and its fork. The wall shear changed with the velocity of the air flow, and its direction changed periodically with breath cycle.
Biomechanical Phenomena ; Bronchi ; physiology ; Computer Simulation ; Epiglottis ; physiology ; Humans ; Mouth ; physiology ; Nose ; physiology ; Pharynx ; physiology ; Pressure ; Pulmonary Ventilation ; physiology ; Respiratory Mechanics ; physiology ; Respiratory Physiological Phenomena ; Respiratory System ; Shear Strength ; Stress, Mechanical ; Trachea ; physiology

The aim of the present study was to evaluate the relation between fat mass (FM), fat free mass (FFM) and ventilatory function in children and adolescents. 1 174 healthy children and adolescents (583 males and 591 females) aged 10-18 years were selected from Heilongjiang Province through random sampling by means of questionnaire and physical examination, and measured for height, weight, waist to hip ratio (WHR), FM, FFM and ventilatory function. The data were analyzed by means of independent-samples t test, Pearson correlation analysis and multi-factors regression analysis. Regardless of sex, an independent positive correlation was found (P<0.001) between age and FFM index (FFMI). FM index (FMI) correlated negatively with age in males (P<0.001), but positively with age in females (P<0.001). Regardless of sex, FFMI correlated positively with forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), forced expiratory flow at 25% of forced vital capacity (FEF25%), FEF50%, and maximal mid-expiratory flow (MMEF) (P<0.05), while negatively with FEV1/FVC (P<0.01). FFMI was correlated positively with FEF75% in males (P<0.05), but not correlated in females. In males, FMI correlated negatively with FEV1, FEV1/FVC, PEF, FEF25%, FEF50%, FEF75% and MMEF (P<0.05), but not correlated with FVC. No correlation was found between the ventilatory function indices and FMI in females. Except FEV1/FVC and FEF75% in males, the effect of FFMI in predicting ventilatory function was higher than FMI regardless of sex. Moreover, the predicting effect of FFMI was higher in males than that in females. Growth spurt of lung function occurred in the ages of 12-15 years in males, while in the ages of 12, 13 and 18 years in females. During the period of growth spurt of lung function, regardless of sex, the effect of FFMI in predicting the lung function was higher than that of age. In conclusion, regardless of sex, FFMI correlates positively with ventilatory function, as a reflection of muscle mass. The effect of FFM in predicting ventilatory function is higher in males than that in females. FM correlates negatively with ventilatory function in males, but not in females. The rapid growth of height and FFM are possibly the main reasons for growth spurt of lung function.
Adipose Tissue ; anatomy & histology ; physiology ; Adolescent ; Body Composition ; physiology ; Body Mass Index ; Child ; Female ; Humans ; Male ; Pulmonary Ventilation ; physiology ; Respiratory Function Tests

The presently used impairment rating guidelines in Korea do not accurately reflect the injury in various lung diseases. Therefore, they need to be made more objective and quantitative with new measurements, using indicators to more precisely represent impairment in the major respiratory diseases. We develop a respiratory impairment rating guideline to ensure that the same grade or impairment rating would be obtained regardless of surgeons who determinate it. Specialists in respiratory medicine and thoracic surgeons determined the impairment grades. Moreover, the impairment should be irreversible for more than 6 months. The impairment rating depends on the level of forced vital capacity, forced expiratory volume 1 second, diffusion capacity of carbon monoxide, arterial oxygen pressure, and arterial carbon dioxide pressure. The degree of whole body impairment is defined by each grade: first 81-95%, second 66-80%, third 51-65%, fourth 36-50%, and fifth 21-35%. In conclusion, we develop a respiratory impairment rating guideline for Koreans. Any qualified specialist can easily use it and judge objective scoring.
*Disability Evaluation ; Humans ; Korea ; Lung Diseases/classification/diagnosis ; Program Development ; Pulmonary Ventilation/physiology ; Respiratory Insufficiency/classification/*diagnosis ; Severity of Illness Index

BACKGROUND: The determinants of intubation and the response to therapy in COPD patients with hypercapnic respiratory failure were retrospectively reviewed. METHODS: This study involved a review of 132 episodes of hypercapnic respiratory failure(PaCO2≥50mmHg and pH≤7.35). The time frame for resolution or the time to intubation of patients who were admitted between 1996 and 1999 was analyzed. RESULTS: Out of 132 hypercapnic episodes, 49(37%) required intubation. A comparison was made with the 83 cases that responded to treatment. Patients requiring intubation had greater severity of illness, which included a higher APACHE II (Acute Physiology and Chronic Health Evaluation II) score (20±5 vs 14±4 ; p<0.01), a higher WBC, a higher serum BUM, and greater acidosis (pH, 7.23±0.11 vs 7.32±0.04 ; p<0.01). Those with the most severe acidosis(pH<7.20) had the highest intubation rate(87%) and shortest time to intubation (2±3 h). Conversely, those with an initial pH 7.31 to 7.35 were less likely to be intubated(20%), and had a longer time to intubation(97±121 h). The patients with a pH 7.21 to 7.25(4.1±2.9 day) required longer period of time to respond to medical treatment than patients with a pH of 7.31 to 7.35(2.2±3.1 day). Of those patients requiring intubation, half(55%) were intubated within 8 h of admission, and most (75%) within 24 h. Of those patients responding to treatment medical therapy, half(52%) recovered within 24 h and most (78%) recovered within 48 h. CONCLUSION: Respiratory acidosis at the initial presentation is associated with an increased likelihood of intubation. This shold assist in deciding help with the decision whether to treat patients medically, institute noninvasive ventilation, or proceed to intubation.
Acidosis ; Acidosis, Respiratory ; APACHE ; Humans ; Hydrogen-Ion Concentration ; Intubation* ; Noninvasive Ventilation ; Physiology ; Pulmonary Disease, Chronic Obstructive* ; Respiratory Insufficiency* ; Retrospective Studies