OBJECTIVETo investigate the differential value of inhaled volume and exhaled volume in anesthesia mice, and its effect on the pressure change inside of plethysmograph.

METHODSPressure and temperature in head chamber of double-chamber plethysmograph were tested when mice were placed in the body chamber. The differential values of inhaled volume and exhaled volume of mice were calculated.

RESULTThe baseline pressure in head chamber increased with temperature rising within 12 minutes, then went down though temperature remained high. The inhaled volumes of 8 mice were (0.2842 + or - 0.0173)ml,and the differential value of inhaled volume and exhaled volume was (0.0012 + or - 0.0002)ml.

CONCLUSIONThe inhaled volume is larger than exhaled volume, which makes pressure baseline of plethysmograph decreased. The differential value may be generated from respiratory quotient.

Animals ; Exhalation ; physiology ; Inhalation ; physiology ; Mice ; Plethysmography ; Pressure ; Temperature ; Tidal Volume ; Vital Capacity ; physiology

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

Pressure-support ventilation (PSV) is a form of important ventilation mode. Patient-ventilator synchrony of pressure support ventilation can be divided into inspiration-triggered and expiration-triggered ones. Whether the ventilator can track the patient's inspiration and expiration very well or not is an important evaluating item of the performance of the ventilator. The ventilator should response to the patient's inspiration effort on time and deliver the air flow to the patient under various conditions, such as different patient's lung types and inspiration effort, etc. Similarly, the ventilator should be able to response to the patient's expiration action, and to decrease the patient lung's internal pressure rapidly. Using the Active Servo Lung (ASL5000) respiratory simulation system, we evaluated the spontaneous breathing of PSV mode on E5, Servo i and Evital XL. The following parameters, the delay time before flow to the patient starts once the trigger variable signaling the start of inspiration, the lowest inspiratory airway pressure generated prior to the initiation of PSV, etc. were measured.
Exhalation ; Humans ; Inhalation ; Interactive Ventilatory Support ; Lung ; physiology ; Pressure ; Ventilators, Mechanical

OBJECTIVETo learn the normal values of exhaled nitric oxide (eNO) in children.

METHODSchool children in Beijing from 11 to 18 years of age were included in the study. All the students were assigned into two groups: normal group and abnormal group (with allergic disease) according to the International Study of Asthma and Allergy in Childhood questionnaires. eNO, peak expiratory flow rate and sensitization were measured.

RESULTTotally 395 students were screened out as normal subject (male: 177, female: 218). The eNO level was not significantly different between genders (P > 0.05), but was associated positively with age in both male and female group (P = 0.008 and P = 0.05 respectively) and associated with height in male students (P = 0.02). The geometric mean value of eNO was 11.22 ppb (parts per billion, ppb = 10(9)) in children aged from 11 to 14 years and 14.13 ppb in children aged from 14 to 18 years, with 95% confidence interval 4.17 - 30.20, 5.50 - 36.31 ppb. The eNO level was significantly increased in children who "ever had asthma or wheezing" (n = 68), and children who "ever had rhinitis" (n = 96) compared with normal subjects (P = 0.001 and P = 0.008). The geometric mean value of eNO was 16.98 ppb in children with positive skin prick test and was significantly increased as compared with children with negative skin prick test with eNO level at 11.75 ppb (P = 0.001).

CONCLUSIONeNO level varied between 10.72 ppb and 13.80 ppb in normal children 11 - 18 years of age, and was positively associated with age and height, but not with gender. eNO level increased significantly in children with wheezing and atopy.

Adolescent ; Asthma ; physiopathology ; Case-Control Studies ; Child ; China ; Exhalation ; physiology ; Female ; Humans ; Male ; Nitric Oxide ; analysis ; physiology

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

OBJECTIVE: The purpose of this study was to compare air trapping in healthy volunteers with asthmatics using pulmonary function test and quantitative data, such as specific volume change from paired inspiratory CT and registered expiratory CT. MATERIALS AND METHODS: Sixteen healthy volunteers and 9 asthmatics underwent paired inspiratory/expiratory CT. DeltaSV, which represents the ratio of air fraction released after exhalation, was measured with paired inspiratory and anatomically registered expiratory CT scans. Air trapping indexes, DeltaSV0.4 and DeltaSV0.5, were defined as volume fraction of lung below 0.4 and 0.5 DeltaSV, respectively. To assess the gravity effect of air-trapping, DeltaSV values of anterior and posterior lung at three different levels were measured and DeltaSV ratio of anterior lung to posterior lung was calculated. Color-coded DeltaSV map of the whole lung was generated and visually assessed. Mean DeltaSV, DeltaSV0.4, and DeltaSV0.5 were compared between healthy volunteers and asthmatics. In asthmatics, correlation between air trapping indexes and clinical parameters were assessed. RESULTS: Mean DeltaSV, DeltaSV0.4, and DeltaSV0.5 in asthmatics were significantly higher than those in healthy volunteer group (all p < 0.05). DeltaSV values in posterior lung in asthmatics were significantly higher than those in healthy volunteer group (p = 0.049). In asthmatics, air trapping indexes, such as DeltaSV0.5 and DeltaSV0.4, showed negative strong correlation with FEF25-75, FEV1, and FEV1/FVC. DeltaSV map of asthmatics showed abnormal geographic pattern in 5 patients (55.6%) and disappearance of anterior-posterior gradient in 3 patients (33.3%). CONCLUSION: Quantitative assessment of DeltaSV (the ratio of air fraction released after exhalation) shows the difference in extent of air trapping between health volunteers and asthmatics.
Adult ; Aged ; Asthma/*physiopathology ; Exhalation/physiology ; Female ; Healthy Volunteers ; Humans ; Lung/*physiopathology/radiography ; Male ; Middle Aged ; *Respiratory Function Tests ; Tomography, X-Ray Computed/methods

The effect of variation of nasal structure on airflow distribution was investigated. Based on the CT images of the nose of a healthy female, a three-dimensional nasal model was developed. Two new nasal models were produced by removing part of inferior turbinate and part of middle turbinate in the left side of the original model. The numerical simulation and analysis for airflow field in the three nasal models was conducted by the finite element method. The simulation results from new models were compared with those from the original model. The airflow rate changed in the two sides of new nasal models. The airflow distribution and the pressure grades varied in the side of nasal model where part of inferior turbinate or part of middle turbinate was removed. The variation of nasal cavity structure will result in airflow redistribution in nasal cavity. The effect of removing turbinate on the airflow distribution in nasal cavity was described quantitatively.
Airway Resistance ; physiology ; Computer Simulation ; Exhalation ; physiology ; Female ; Finite Element Analysis ; Humans ; Image Processing, Computer-Assisted ; Inhalation ; physiology ; Models, Biological ; Nasal Cavity ; diagnostic imaging ; physiology ; Tomography, X-Ray Computed ; Turbinates ; surgery

OBJECTIVETo obtain the normal values of nitric oxide (NO) exhaled through nose and mouth in healthy Chinese adults by measuring exhaled NO and analyzing the influencing factors.

METHODSEighty healthy Chinese adults were recruited, including 20 males and 60 females. The age ranged from 18 to 44 years old. Chemiluminescence analyzer (NIOX) was used to obtain the values of exhaled NO through nose and mouth. The relativity between NO and gender, age, height, body mass index, time, ambient NO were analyzed with Multiple linear regression and correlation.

RESULTSExhaled NO values were (17+/-8)x10(-9) and correlated significantly with height. Regression equation: Y (exhaled nitric oxide)=-58.524+0.457X (height, cm), t=-2.985, P<0.01. Transnasal NO values were (819+/-211)x10(-9) and correlated significantly with age and gender. Regression equation: Y (nasal nitric oxide)=760.245+9.417X1(age)-111.222X2(gender), t=5.188, P<0.01.

CONCLUSIONSExhaled NO normal values were 17x10(-9) and Transnasal NO normal values were 819x10(-9). Exhaled NO correlated positively with height. Transnasal NO correlated positively with age and negatively with gender.

Adolescent ; Adult ; Age Factors ; Asian Continental Ancestry Group ; Body Height ; Body Mass Index ; Breath Tests ; Exhalation ; physiology ; Female ; Humans ; Male ; Mouth ; physiology ; Nitric Oxide ; analysis ; Nose ; physiology ; Reference Values ; Sex Factors ; Young Adult