In order to improve synchrony between a ventilator and its patient, a new method for triggering a ventilator based on diaphragmatic electromyogram (EMG) is introduced. The methods to extract and process diaphragmatic EMG signals are studied. It has been shown that the characteristic parameters of a respiration activity, such as inspiratory beginning point, expiratory beginning point and respiration period, can be detected from diaphragmatic EMG envelop instead of traditional flux curve. A new parameter, designated as diaphragmatic "Intensity of EMG" for short "IEMG", is defined. Repeat respiration tests have disclosed that there is relatively high correlation between the diaphragmatic IEMG curve and its corresponding cubage curve. These results primarily demonstrate that the new synchronization method may be feasible.
Diaphragm ; physiology ; Electromyography ; Humans ; Positive-Pressure Respiration ; methods ; Respiration ; Respiration, Artificial ; methods ; Respiratory Insufficiency ; therapy ; Respiratory Muscles ; physiology ; Work of Breathing ; 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 is to evaluate the airway dynamics of the upper airway as depicted on cine MRI in children with tracheotomy tubes during two states of airflow through the upper airway. MATERIALS AND METHODS: Sagittal fast gradient echo cine MR images of the supra-glottic airway were obtained with a 1.5T MRI scanner on seven children with tracheotomy tubes. Two sets of images were obtained with either the tubes capped or uncapped. The findings of the cine MRI were retrospectively reviewed. Volume segmentation of the cine images to compare the airway volume change over time (mean volume, standard deviation, normalized range, and coefficient of variance) was performed for the capped and uncapped tubes in both the nasopharynx and hypopharynx (Signed Rank Test). RESULTS: Graphical representation of the airway volume over time demonstrates a qualitative increased fluctuation in patients with the tracheotomy tube capped as compared to uncapped in both the nasopharyngeal and hypopharyngeal regions of interest. In the nasopharynx, the mean airway volume (capped 2.72 mL, uncapped 2.09 mL, p = 0.0313), the airway volume standard deviation (capped 0.42 mL, uncapped 0.20 mL, p = 0.0156), and the airway volume range (capped 2.10 mL, uncapped 1.09 mL, p = 0.0156) were significantly larger in the capped group of patients. In the hypopharynx, the airway volume standard deviation (capped 1.54 mL, uncapped 0.67 mL, p = 0.0156), and the airway volume range (capped 6.44 mL, uncapped 2.93 mL, p = 0.0156) were significantly larger in the capped tubes. The coefficient of variance (capped 0.37, uncapped 0.26, p = 0.0469) and the normalized range (capped 1.52, uncapped 1.09, p = 0.0313) were significantly larger in the capped tubes. CONCLUSION: There is a statistically significant change in airway dynamics in children with tracheotomy tubes when breathing via the airway as compared to breathing via the tracheotomy tube.
Adolescent ; Child ; Child, Preschool ; Female ; Humans ; Hypopharynx/anatomy & histology/*physiology ; Image Processing, Computer-Assisted ; Magnetic Resonance Imaging, Cine/*methods ; Male ; Nasopharynx/anatomy & histology/*physiology ; Retrospective Studies ; Time Factors ; Tracheostomy/*instrumentation ; Work of Breathing/*physiology