BACKGROUNDObstructive sleep apnea is strongly associated with obesity, particularly abdominal obesity common in centrally obese males. Previous studies have demonstrated that intra-abdominal pressure (IAP) is increased in morbid obesity, and tracheal traction forces may influence pharyngeal airway collapsibility. This study aimed to investigate that whether IAP plays a role in the mechanism of upper airway (UA) collapsibility via IAP-related caudal tracheal traction.

METHODSAn abdominal wall lifting (AWL) system and graded CO2pneumoperitoneum pressure was applied to four supine, anesthetized Guizhou miniature pigs and its effects on tracheal displacement (TD) and airflow dynamics of UA were studied. Individual run data in 3 min obtained before and after AWL and obtained before and after graded pneumoperitoneum pressure were analyzed. Differences between baseline and AWL/graded pneumoperitoneum pressure data of each pig were examined using a Student's t-test or analysis of variance.

RESULTSApplication of AWL resulted in decreased IAP and significant caudal TD. The average displacement amplitude was 0.44 mm (P < 0.001). There were three subjects showed increased tidal volume (TV) (P < 0.01) and peak inspiratory airflow (P < 0.01); however, the change of flow limitation inspiratory UA resistance (Rua) was not significant. Experimental increased IAP by pneumoperitoneum resulted in significant cranial TD. The average displacement amplitude was 1.07 mm (P < 0.001) when IAP was 25 cmH2O compared to baseline. There were three subjects showed reduced Rua while the TV increased (P < 0.01). There was one subject had decreased TV and elevated Rua (P < 0.001).

CONCLUSIONSDecreased IAP significantly increased caudal TD, and elevated IAP significantly increased cranial TD. However, the mechanism of UA collapsibility appears primarily mediated by changes in lung volume rather than tracheal traction effect. TV plays an independent role in the mechanism of UA collapsibility.

Airway Resistance ; physiology ; Animals ; Female ; Lung Volume Measurements ; Obesity, Morbid ; physiopathology ; Sleep Apnea, Obstructive ; physiopathology ; Swine ; Tidal Volume ; physiology ; Trachea ; physiology

BACKGROUNDFor patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) and type 2 diabetes mellitus (T2DM), the night sleep interruption and intermittent hypoxia due to apnea or hypopnea may induce glycemic excursions and reduce insulin sensitivity. This study aimed to investigate the effect of continuous positive airway pressure (CPAP) therapy in patients with OSAHS and T2DM.

METHODSContinuous glucose monitoring system (CGMS) was used in 40 patients with T2DM and newly diagnosed OSAHS. The measurements were repeated after 30 days of CPAP treatment. Subsequently, insulin sensitivity and glycohemoglobin (HbA1c) were measured and compared to the pretreatment data.

RESULTSAfter CPAP therapy, the CGMS indicators showed that the 24-h mean blood glucose (MBG) and the night time MBG were significantly reduced (P < 0.05 and P = 0.03, respectively). The mean ambulatory glucose excursions (MAGEs) and the mean of daily differences were also significantly reduced (P < 0.05 and P = 0.002, respectively) compared to pretreatment levels. During the night, MAGE also significantly decreased (P = 0.049). The differences between the highest and lowest levels of blood glucose over 24 h and during the night were significantly lower than prior to CPAP treatment (P < 0.05 and P = 0.024, respectively). The 24 h and night time durations of high blood glucose (>7.8 mmol/L and > 11.1 mmol/L) decreased (P < 0.05 and P < 0.05, respectively) after the treatment. In addition, HbA1c levels were also lower than those before treatment (P < 0.05), and the homeostasis model assessment index of insulin resistance was also significantly lower than before CPAP treatment (P = 0.034).

CONCLUSIONSCPAP therapy may have a beneficial effect on improving not only blood glucose but also upon insulin sensitivity in T2DM patients with OSAHS. This suggests that CPAP may be an effective treatment for T2DM in addition to intensive diabetes management.

Adult ; Blood Glucose ; physiology ; Continuous Positive Airway Pressure ; methods ; Diabetes Mellitus, Type 2 ; therapy ; Female ; Humans ; Insulin Resistance ; physiology ; Male ; Middle Aged ; Sleep Apnea, Obstructive ; therapy ; Treatment Outcome

OBJECTIVEBody plethysmography is a typical method to measure functional residual capacity (FRC) and airway resistance (Raw). The aim of the study was to test the feasibility of measuring lung function with the body plethysmography in young children with acute lower respiratory tract infection (ALRI) by evaluating changes and prognosis of lung function for infants with ALRI with or without wheezing via body plethysmograph.

METHODPulmonary function tests (PFTs) were performed by using body plethysmography in 444 children with ALRI, aged 1-36 months, to assess their tidal breathing parameters such as ratio of time to peak tidal expiratory flow to total expiratory time (TPTEF/TE), ratio of volume to peak tidal expiratory flow to total expiratory volume (VPTEF/VE), plethysmographic functional residual capacity (FRCP), FRCP per kilogram (FRCP/kg), specific effective airway resistance (sReff), effective airway resistance (Reff), Reff per kilogram (Reff/kg), etc. According to whether there was wheezing or not, children who had ALRI with wheezing were classified as Group-W, or without wheezing as Group-N. Changes or correlations of tidal breathing parameters and plethysmographic parameters were compared.One hundred and three contemporaneous healthy controls aged 1-36 months underwent the same tests for comparison. And 36 wheezing children accepted PFTs at follow-up in recovery phase.

RESULTMean values of TPTEF/TE in Group-W,Group-N and the Control respectively were (20.5 ± 6.7)%,(22.8 ± 6.5)%,(34.6 ± 5.0)% (F = 110.500, P < 0.001), while VPTEF/VE respectively were (23.0 ± 6.3)%,(25.2 ± 6.8)%,(34.5 ± 4.2)% (F = 107.800, P < 0.001). Compared to the Control,Group-W and Group-N had significantly higher values of FRCP (226 vs. 176 vs. 172 ml, χ(2) = 64.870, P < 0.001), FRCP/kg(24.40 vs.17.80 vs.17.60 ml/kg,χ(2) = 68.890, P < 0.001), sReff(1.00 vs. 0.52 vs. 0.46 kPa·s,χ(2) = 75.240, P < 0.001), Reff (3.90 vs.2.74 vs.2.20 kPa·s/L, χ(2) = 36.480, P < 0.001) and Reff/kg [0.42 vs. 0.29 vs.0.22 kPa·s/(L·kg), χ(2) = 29.460, P < 0.001]. Although 25 (12.8%) wheezing children with ALRI had normal values of tidal breathing parameters, they already had increased FRCP, FRCP /kg, sReff, Reff and Reff/kg (t = 2.221, 1.997, 2.502, 2.587, 2.539, all P < 0.05). Values of FRCP and Reff in infants caught ALRI were inversely correlated to that of TPTEF/TE and VPTEF/VE (P < 0.05); 36 children with wheezing who accepted PFTs at follow-up had shown significant decline in the specific parameters of plethysmography such as FRCP, FRCP/kg, sReff, Reff and Reff/kg (Z = -1.999, -2.195, -2.038, -1.823, -2.054, all P < 0.05), while no improvement in the main parameters of tidal breathing such as TPTEF/TE.

CONCLUSIONMeasuring lung function with the body plethysmography in young children with ALRI is feasible. FRC and Raw, as special lung function testing parameters of body plethysmography, were sensitive indicators reflecting impairment of lung function in infants with ALRI (especially for children caught ALRI with wheezing) and shows significant correlation with parameters from lung function testing via tidal breathing. Therefore plethysmography is worthy of clinical promotion.

Airway Resistance ; physiology ; Case-Control Studies ; Child, Preschool ; Female ; Functional Residual Capacity ; physiology ; Humans ; Infant ; Lung ; physiopathology ; Male ; Plethysmography, Whole Body ; Respiratory Function Tests ; Respiratory Sounds ; diagnosis ; physiopathology ; Respiratory Tract Diseases ; diagnosis ; physiopathology ; Tidal Volume

BACKGROUND: Perforations in the nasal septum (NSP) give rise not only to disintegration of the septum anatomy but also impairment in normal nasal physiology. The successes of these surgical techniques are usually equated to anatomical closure of the perforation. The goal of this study is to evaluate the subjective and objective results of our surgical technique for septal perforation surgery. METHODS: All NSPs in the six patients were closed by inferior turbinate flap. The Nasal Obstruction Symptom Evaluation (NOSE) instrument was used to evaluate the preoperative and postoperative subjective sensation of nasal obstruction. Measurement of preoperative and postoperative nasal airway resistance was performed using active anterior rhinomanometry which is an objective test. Wilcoxson signed rank test and Spearman correlation test were used to analyze correlation between NOSE scores and rhinomanometric measurements. RESULTS: The full closure of the septal perforations was noted in 100% of patients. The total NOSE score was 14 preoperatively and one postoperatively. The improvement in NOSE scores was statistically significant (P< or =0.002). The mean preoperative total resistance (ResT150) value was 0.13 Pa/cm(3)s(-1), which is below the normal range (0.16-0.31 Pa/cm(3)s(-1)), while the mean postoperative ResT150 value was 0.27 Pa/cm3s-1. The correlation between the improvement in NOSE scores and improvements in ResT150 values was statistically significant. CONCLUSIONS: Surgical approaches should aim to solve both the anatomical and physiological problems of NSP. The application of subjective and objective tests in the postoperative period will help surgeons assess the applied techniques.
Airway Resistance ; Humans ; Nasal Obstruction ; Nasal Septal Perforation* ; Nasal Septum ; Nose ; Physiology ; Postoperative Period ; Reference Values ; Rhinomanometry ; Sensation ; Symptom Assessment ; Turbinates

BACKGROUNDObesity is a common risk factor for several diseases. Obesity related hormone and increased insulin resistance (IR) may contribute to the effects of obstructive sleep apnoea on cardiovascular consequences. We investigated ghrelin and IR in non-diabetic apnoeic patients with stable coronary heart disease and assessed the effects of continuous positive airway pressure (CPAP).

METHODSPlasma ghrelin, glucose and insulin were measured in 22 patients with CPAP and 22 matched controls without CPAP at baseline and three months. Indexes including homeostasis model assessment IR (HOMA IR), HOMA S and HOMA β were calculated for the assessment of IR, insulin sensitivity and pancreatic β cell function.

RESULTSAt three months follow-up, plasma ghrelin levels and HOMA IR in CPAP group were significantly decreased (P=0.002 and 0.046, respectively) while those in control group increased significantly (P=0.012 and 0.009, respectively). Significant moderate correlations were found between ghrelin vs. HOMA IR and ghrelin vs. HOMA S after CPAP, however, for those without CPAP, no significant associations were observed.

CONCLUSIONSShort-term effective continuous positive airway pressure had a significant effect on lowering plasma ghrelin levels and IR, but not body fat. Further large scale and longer term studies are warranted to corroborate these findings.

Blood Glucose ; Case-Control Studies ; Continuous Positive Airway Pressure ; methods ; Coronary Artery Disease ; blood ; Female ; Ghrelin ; blood ; Humans ; Insulin ; blood ; Insulin Resistance ; physiology ; Male ; Middle Aged ; Sleep Apnea, Obstructive ; therapy

Respirator breathing resistance impacts performance of wearers during constant work load. However, it is less clear as to how breathing resistance affects the tolerant capacity of users during graded work load. The present study investigated the tolerant capacity of 8 individuals during incremental work load. The 8 subjects were required to wear two matched respirators (respirators I and II which were designed to have different breathing resistances and the same dead space) respectively on separate days and then work to end points. Minute ventilation (V(E)), breathing frequency (BF), oxygen consumption (VO(2)) and heart rate (HR) were recorded during exercise, while tolerant time, response time and breathing discomfort were measured at the end of each test trial. The test variables were compared between the two respirators by using matched-pairs t-test. The results showed that the tolerant time was significantly reduced for the respirator I with higher level of breathing resistance when compared with its counterpart with lower breathing resistance (respirator II) (P<0.05). The same changes occurred for response time. Results also showed a significant increase in V(E) and BF for respirator I wearers when the work load was above 125 W. The O(2) consumption was similar under the two breathing resistance conditions. These findings suggested that the respiratory resistance caused by self-contained breathing apparatus (SCBA) has an impact on the tolerant capacity of users.
Airway Resistance ; physiology ; Exercise ; physiology ; Exercise Tolerance ; physiology ; Humans ; Male ; Oxygen Consumption ; physiology ; Physical Exertion ; physiology ; Respiration, Artificial ; methods ; Respiratory Mechanics ; physiology ; Young Adult

A reduction in diaphragm mobility has been identified in patients with chronic obstructive pulmonary disease (COPD) and has been associated with a decline in pulmonary function parameters. However, little information exists regarding the potential role of diaphragm mobility on hypercapnia in COPD. A new method of assessing the mobility of the diaphragm, using ultrasound, has recently been validated. The purpose of the present study was to investigate the relationship between diaphragm mobility and pulmonary function parameters, as well as that between arterial blood gas values and diaphragm mobility, in COPD patients. Thirty seven COPD patients were recruited for pulmonary function test, arterial blood gas analysis and diaphragm mobility using ultrasound to measure the craniocaudal displacement of the left branch of the portal vein. There were significant negative correlations between diaphragmatic mobility and PaCO2 (r = -0.373, P = 0.030). Diaphragmatic mobility correlated with airway obstruction (FEV1, r = 0.415, P = 0.011) and with ventilatory capacity (FVC, r = 0.302, P = 0.029; MVV, r = 0.481, P = 0.003). Diaphragmatic mobility also correlated significantly with pulmonary hyperinflation. No relationship was observed between diaphragm mobility and PaO2 (r = -0.028, P = 0.873). These findings support a possibility that the reduction in diaphragm mobility relates to hypercapnia in COPD patients.
Aged ; Airway Resistance/physiology ; Carbon Dioxide/blood/physiology ; Diaphragm/physiopathology/*ultrasonography ; Female ; Humans ; Hypercapnia/complications/*physiopathology ; Male ; Middle Aged ; Portal Vein ; Pulmonary Disease, Chronic Obstructive/complications/*physiopathology/ultrasonography ; Pulmonary Gas Exchange ; Respiratory Muscles/physiopathology

OBJECTIVE: To obtain the normal values of acoustic rhinometry and rhinomanometry parameters of normal adult and analyze the correlation of two measurement results between rhinomanometry and acoustic rhinometry. METHOD: Eighty-two normal adults were recruited in our research. Acoustic rhinometry was used to acquire unilateral area of first constriction (UA1), unilateral area of second of constriction (UA2), unilateral minimum cross-sectional area (UMCA), unilateral nasal volume 0-5 cm, 2-5 cm (UV5, UV2-5), and rhinomanometer was used to measure the effective unilateral and total nasal resistances in inspiration, expiration at 150 Pa or Broms (radius is 200 Pa) (UR(ins150), UR(ins200), UR(exp150), UR(exp200), TR(ins150), TR(ins200), TR(exp150), TR(exp200)). RESULT: UA1 was (0.63 +/- 0.14) cm2 for male, (0.60 +/- 0.14) cm2 for female; UA2 was (0.72 +/- 0.48) cm2 for male, (0.6 +/- 0.4) cm2 for female; UMCA was (0.50 +/- 0.16) cm2 for male, (0.47 +/- 0.18) cm2 for female; UV5 was (5.68 +/- 1.73) cm3 for male, (5.16 +/- 1.85) cm3 for female; UV2-5 was (4.13 +/- 1.56) cm3 for male, (3.83 +/- 1.66) cm3 for female. No statistical significance was found between men and women (T = 0.093, 0.134, 0.392, 0.408, P > 0.05). UR(ins150) was (0.86 +/- 0.96) Pa/(cm3 x s); UR(ins200) was (0.45 +/- 0.61) Pa/(cm3 x s); UR(exp150) was (0.83 +/- 0.71) Pa/(cm3 x s); UR exp200 was (0.52 +/- 0.88) Pa/(cm3 x s); TR(ins150) was (0.38 +/- 0.34) Pa/(cm3 x s); TR(ins200) was (0.18 +/- 0.24) Pa/ (cm3 x s); TRp(exp150) was (0.38 +/- 0.27) Pa/(cm3 x s); TR(exp200) was (0.19 +/- 0. 24) Pa/(cm3 x s). There was significant correlation between UR(ins150), UR(exp150), TR(ins150), TR(exp150 and UMCA, UV5, UV2 - 5 (P < 0.05, respectively). CONCLUSION There was correlation between acoustic rhinometry and rhinomanometry. The results of this study can be used as a valuable reference to judge nasal cavity condition of normal adult.
Adolescent ; Adult ; Airway Resistance ; Female ; Humans ; Male ; Middle Aged ; Nasal Cavity ; physiology ; Reference Values ; Rhinomanometry ; Rhinometry, Acoustic ; Young Adult

Mechanical force plays an important role in physiological function and pathophysiologic conditions of respiratory system. Recently, a number of researches focused on how mechanical force affected pulmonary cells. This paper reviews the molecular basis of mechanical force in detail. The significance of mechanical force in respiratory therapy is also discussed.
Airway Resistance ; Biomechanical Phenomena ; Humans ; Lung Compliance ; Respiratory Mechanics ; physiology ; Respiratory Physiological Phenomena ; Respiratory System

BACKGROUNDThe down-regulation of constitutive nitric oxide synthase (cNOS) and up-regulation of inducible nitric oxide synthase (iNOS) are associated with the allergen-provocated airway hyperresponsiveness (AHR). This study aimed to determine whether their alteration also plays an important role in the AHR induced by lipopolysaccharide (LPS).

METHODSHartley male guinea pigs, weighing between 250 g and 350 g, were injected with LPS at a dose of 1 mg/kg every 24 hours for three days. A non-selective NOS inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME), or a selective inducible NOS inhibitor, aminoguanidine (AG), were used thirty minutes before each injection of LPS. Airway reactions, nitric oxide (NO) production and inflammatory changes were detected 24 hours after the last dose of LPS.

RESULTSAG significantly decreased the NO production in the bronchoalveolar lavage fluid (BALF) and sharply reduced the intensity of bronchoconstriction to histamine challenge. L-NAME also significantly decreased the NO production in the BALF, but had no effect on airway reactions or, perhaps, a tendency to enhance the intensity of AHR.

CONCLUSIONSThe data suggest that inducible NOS contributes to the AHR induced by repetitive intraperitoneal LPS, and constitutive NOS was also involved.

Airway Resistance ; drug effects ; Animals ; Bronchial Hyperreactivity ; chemically induced ; Enzyme Inhibitors ; pharmacology ; Guanidines ; pharmacology ; Guinea Pigs ; Lipopolysaccharides ; toxicity ; Male ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; biosynthesis ; Nitric Oxide Synthase ; antagonists & inhibitors ; physiology