Performance comparison of two oscillating positive expiratory pressure devices: Acapella versus Flutter. (1/46)

BACKGROUND: Oscillatory positive expiratory pressure (PEP) with the Flutter device facilitates secretion removal. In the Flutter a steel ball vibrates inside a cone, causing air flow vibration. A new device, the Acapella, uses a counterweighted plug and magnet to create air flow oscillation. The Acapella comes in 2 models: one for patients with expiratory flow > or = 15 L/min and one for < or = 15 L/min. We hypothesized that the Acapella and Flutter would produce similar mean PEP, oscillatory pressure amplitude, and frequency over a clinically relevant range of flows. METHODS: We measured oscillatory amplitude, PEP, and frequency. Values for frequency, peak, trough, and mean pressure were recorded automatically every 3 seconds at flows of 5, 10, 15, 20, 25, and 30 L/min. The pressure waveform for 1 second was also graphically displayed and recorded. The devices were adjusted to give low, medium, and high mean expiratory pressure (Flutter angle at 0, 20, and 40 degrees; Acapella by dial setting). Data were analyzed by 2-way repeated measures analysis of variance, and differences were considered significant when p was < 0.05. RESULTS: There were statistically significant differences between the devices for mean pressure, pressure amplitude, and frequency, for all experimental conditions. However, the differences were relatively small and may not be clinically important. Both devices produced similar pressure waveforms at the medium flows. At 5 L/min the Acapella produced a more stable waveform, with a lower frequency, higher amplitude, and a slightly wider range of PEP than the Flutter. CONCLUSIONS: Acapella and Flutter have similar performance characteristics. Acapella's performance is not gravity-dependent (ie, dependent on device orientation) and may be easier to use for some patients, particularly at low expiratory flows.  (+info)

Pulmonary hyperinflation and respiratory distress following solvent aspiration in a patient with asthma: expectoration of bronchial casts and clinical improvement with high-frequency chest wall oscillation. (2/46)

An 18-year-old student with a history of asthma accidentally inhaled organic solvent during a class, with immediate cough and dyspnea that worsened over several hours. He presented in severe respiratory distress, with hypoxemia and marked pulmonary hyperinflation. Administration of inhaled bronchodilator was ineffective because of agitation, and the patient could not be positioned for chest physiotherapy to treat presumed widespread mucus plugging. High-frequency chest wall oscillation (HFCWO) in the sitting position initially caused increased distress but was subsequently tolerated when noninvasive positive-pressure ventilation (NPPV) via nasal mask was initiated. Almost immediately, the patient began expectorating bronchial mucus casts, with concomitant clinical improvement. Endotracheal intubation was avoided, and with aggressive pharmacologic treatment for acute severe asthma and continuation of intermittent HFCWO-NPPV, the patient made a full recovery over the next several days. This case suggests that the combination of HFCWO and NPPV may be helpful in the presence of mucus plugging as a complication of acute inhalation injury or acute severe asthma.  (+info)

Cariporide enables hemodynamically more effective chest compression by leftward shift of its flow-depth relationship. (3/46)

When given during closed-chest resuscitation, cariporide (4-isopropyl-methylsulfonylbenzoyl-guanidine methanesulfonate; a selective inhibitor of the Na(+)/H(+) exchanger isoform-1) enables generation of viable perfusion pressures with less depth of compression. We hypothesized that this effect results from greater blood flows generated for a given depth of compression. Two series of 14 rats each underwent 10 min of untreated ventricular fibrillation followed by 8 min of chest compression before defibrillation was attempted. Compression depth was adjusted to maintain an aortic diastolic pressure (ADP) between 26 and 28 mmHg in the first series and between 36 and 38 mmHg in the second series. Within each series, rats were randomized to receive cariporide (3 mg/kg) or NaCl (0.9%; control) before chest compression was started. Blood flow was measured using 15-mum fluorescent microspheres. Less depth of compression was required to maintain the target ADP when cariporide was present in both series 1 (13.6 +/- 1.2 vs. 16.6 +/- 1.2 mm; P < 0.001) and series 2 (15.3 +/- 1.0 vs. 18.9 +/- 1.5 mm; P < 0.001). Despite less compression depth, the cardiac index in cariporide-treated rats was comparable to control rats in series 1 (11.1 +/- 0.7 vs. 11.3 +/- 1.4 ml.min(-1).kg(-1); P = not significant) but higher in series 2 (15.5 +/- 2.3 vs. 9.9 +/- 1.4 ml.min(-1).kg(-1); P < 0.05). Increases in compression depth (from series 1 to series 2) increased myocardial, cerebral, and adrenal blood flow in cariporide-treated rats. We conclude that cariporide enhances the efficacy of closed-chest resuscitation by leftward shift of the flow-depth relationship.  (+info)

Investigation of non-uniform airflow signal oscillation during high frequency chest compression. (4/46)

BACKGROUND: High frequency chest compression (HFCC) is a useful and popular therapy for clearing bronchial airways of excessive or thicker mucus. Our observation of respiratory airflow of a subject during use of HFCC showed the airflow oscillation by HFCC was strongly influenced by the nonlinearity of the respiratory system. We used a computational model-based approach to analyse the respiratory airflow during use of HFCC. METHODS: The computational model, which is based on previous physiological studies and represented by an electrical circuit analogue, was used for simulation of in vivo protocol that shows the nonlinearity of the respiratory system. Besides, airflow was measured during use of HFCC. We compared the simulation results to either the measured data or the previous research, to understand and explain the observations. RESULTS AND DISCUSSION: We could observe two important phenomena during respiration pertaining to the airflow signal oscillation generated by HFCC. The amplitudes of HFCC airflow signals varied depending on spontaneous airflow signals. We used the simulation results to investigate how the nonlinearity of airway resistance, lung capacitance, and inertance of air characterized the respiratory airflow. The simulation results indicated that lung capacitance or the inertance of air is also not a factor in the non-uniformity of HFCC airflow signals. Although not perfect, our circuit analogue model allows us to effectively simulate the nonlinear characteristics of the respiratory system. CONCLUSION: We found that the amplitudes of HFCC airflow signals behave as a function of spontaneous airflow signals. This is due to the nonlinearity of the respiratory system, particularly variations in airway resistance.  (+info)

Inspiratory oscillatory flow with a portable ventilator: a bench study. (5/46)

INTRODUCTION: We observed an oscillatory flow while ventilating critically ill patients with the Drager Oxylog 3000 transport ventilator during interhospital transfer. The phenomenon occurred in paediatric patients or in adult patients with severe airway obstruction ventilated in the pressure-regulated or pressure-controlled mode. As this had not been described previously, we conducted a bench study to investigate the phenomenon. METHODS: An Oxylog 3000 intensive care unit ventilator and a Drager Medical Evita-4 NeoFlow intensive care unit ventilator were connected to a Drager Medical LS800 lung simulator. Data were registered by a Datex-S5 Monitor with a D-fend flow and pressure sensor, and were analysed with a laptop using S5-Collect software. Clinical conditions were simulated using various ventilatory modes, using various ventilator settings, using different filters and endotracheal tubes, and by changing the resistance and compliance. Data were recorded for 258 combinations of patient factors and respirator settings to detect thresholds for the occurrence of the phenomenon and methods to overcome it. RESULTS: Under conditions with high resistance in pressure-regulated ventilation with the Oxylog 3000, an oscillatory flow during inspiration produced rapid changes of the airway pressure. The phenomenon resulted in a jerky inspiration with high peak airway pressures, higher than those set on the ventilator. Reducing the inspiratory flow velocity was effective to terminate the phenomenon, but resulted in reduced tidal volumes. CONCLUSION: Oscillatory flow with potentially harmful effects may occur during ventilation with the Drager Oxylog 3000, especially in conditions with high resistance such as small airways in children (endotracheal tube internal diameter <6 mm) or severe obstructive lung diseases or airway diseases in adult patients.  (+info)

Physiologic evidence for high-frequency chest wall oscillation and positive expiratory pressure breathing in hospitalized subjects with cystic fibrosis. (6/46)

BACKGROUND AND PURPOSE: This investigation identified ventilation distribution, gas mixing, lung function, and arterial blood oxyhemoglobin saturation (SpO2) physiologic responses to 2 independent airway clearance treatments, high-frequency chest wall oscillation (HFCWO) and low positive expiratory pressure (PEP) breathing, for subjects who had cystic fibrosis (CF) and who were hospitalized during acute and subacute phases of a pulmonary exacerbation. SUBJECTS: Fifteen subjects with moderate to severe CF were included in this study. METHODS: Subjects performed single-breath inert gas tests and spirometry before and immediately after HFCWO and PEP breathing at admission and discharge. Arterial blood oxyhemoglobin saturation was monitored throughout each treatment. RESULTS: At admission and discharge, PEP breathing increased SpO2 during treatment, whereas HFCWO decreased SpO2 during treatment. Ventilation distribution, gas mixing, and lung function improved after HFCWO or PEP breathing. DISCUSSION AND CONCLUSION: High-frequency chest wall oscillation and PEP breathing are similarly efficacious in improving ventilation distribution, gas mixing, and pulmonary function in hospitalized people with CF. Because SpO2 decreases during HFCWO, people who have moderate to severe CF and who use HFCWO should have SpO2 monitored during an acute exacerbation.  (+info)

Physiological effects of vibration in subjects with cystic fibrosis. (7/46)

The physiological mechanisms by which vibration and other physiotherapy interventions may clear secretions in subjects with cystic fibrosis are unknown. The main aim of this study was to compare the expiratory flow rates and frequencies of airflow oscillation of vibration to those of Acapella(R), Flutter(R), positive expiratory pressure and percussion. Respiratory flow rates were measured during interventions, the order of which was randomised. The oscillation of the airflow of the interventions was determined by frequency spectral analysis. In 18 young adult subjects with cystic fibrosis, the mean peak expiratory flow rate of vibration was greater than Flutter(R), percussion, Acapella(R) and positive expiratory pressure. The mean+/-sd of the oscillation of the airflow of vibration (8.4+/-0.4 Hz) was lower than Acapella(R) (13.5+/-1.7 Hz) and Flutter(R) (11.3+/-1.5 Hz) but similar to percussion (7.3+/-0.3 Hz). Theoretically, the higher peak expiratory flow rate of vibration compared to the other physiotherapy interventions may promote secretion clearance. In addition, the frequency of oscillation of vibration was within the range demonstrated to increase mucus transport. This study has provided some evidence for the physiological rationale for the use of vibration to aid secretion clearance.  (+info)

Immediate changes in blood-gas tensions during chest physiotherapy with positive expiratory pressure and oscillating positive expiratory pressure in patients with cystic fibrosis. (8/46)

OBJECTIVE: To assess and compare immediate effects of chest physiotherapy with positive expiratory pressure (PEP) versus oscillating PEP on transcutaneously measured blood-gas tensions in patients with cystic fibrosis. METHODS: Fifteen patients (mean age 12.5 y, range 6.9-21.5 y) participated. The treatments were randomized and performed on 2 separate occasions, 8 weeks apart. Spirometry was conducted before and after each treatment. We transcutaneously measured oxygen tension (P(tO2). RESULTS: There were no changes in spirometry values. During PEP, different trends in blood-gas tension were seen, and there were no consistent changes. During oscillating PEP, P(tO2) increased and P(tCO2) decreased. During oscillating PEP, P(tCO2) was lower and the intra-individual change in P(tCO2) was more pronounced than during PEP. The results obtained immediately after oscillating PEP showed a higher P(tO2) and a lower P(tCO2) than with PEP. CONCLUSION: PEP and oscillating PEP can both cause transitory effects on blood gases in patients with cystic fibrosis. However, oscillating PEP alters blood-gas tensions more than does PEP, and hyperventilation during oscillating PEP may reduce treatment time.  (+info)

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