Chest
Diaphragmatic Rest During Negative Pressure Ventilation by Pneumowrap: Assessment in Normal and COPD Patients
Section snippets
MATERIALS AND METHODS
Five normal nonsmoking subjects (one woman) and six COPD patients agreed to take part in the study. In the normal group, two of the subjects were aware of the purpose of the study, but none had previously been submitted to an INPV trial, while all the patients had received INPV sessions for the previous three days. The mean age of normal subjects was 35.6 ± 4.1 years, and their static and dynamic volumes were measured by body plethysmography and found to be within normal limits. The
RESULTS
During the first 5 to 10 minutes of INPV at the pressures of –15 cmH2O and –30 cmH2O, the response of all the variables considered was very irregular. For this reason, we only analyzed the data obtained when all the variables were stabilized. Indeed, 2 to 4 minutes were required for the pressure recorded inside the pneumowrap to reach a stable desired value, even if the pressure set on the manometer of the ventilator was fixed from the beginning. End-expiratory volume, as assessed by RIP,
DISCUSSION
In this study, we provide evidence that in normal subjects and in a group of trained COPD patients, negative pressure ventilation by pneumowrap, using pressure swings of –15 cmH2O and –30 cmH2O and after adaptation, induces partial diaphragmatic rest, as assessed by a decrease in electrical and mechanical activity of the diaphragm. After a few minutes, a 1:1 phase lock developed between the spontaneous respiratory rhythm and that of the mechanical ventilator (Figure 7, Figure 8).
A previous
ACKNOWLEDGMENT
The authors wish to thank Miss Jacqueline McKay for kindly reviewing the manuscript.
REFERENCES (25)
- et al.
Clinical manifestation of inspiratory muscle fatigue
Am J Med
(1982) - et al.
Bilateral diaphragm paralysis treated with cuirass ventilation
Chest
(1987) - Rochester DF, Martin LL. Respiratory muscle rest. In: Roussos C, Macldem PT, eds. The thorax. New York: Dekker,...
- et al.
Intermittent negative pressure ventilation in severe COPD
Am Rev Respir Dis
(1987) - et al.
Effects of 8 weeks of intermittent negative pressure ventilation on exercise in patients with severe chronic obstructive lung disease
Am Rev Respir Dis
(1985) - Ambrosino N, Montagna T, Nava S, Negri A, Brega S, Fracchia C, et al. Short term effect of intermittent negative...
- et al.
Evaluation of intermittent long-term negative pressure ventilation in patients with severe chronic obstructive pulmonary disease
Am Rev Respir Dis
(1988) - et al.
Weekly cuirass ventilation improves blood gases, inspiratory muscle strength in patients with chronic airflow limitation and hypercapnia
Am Rev Respir Dis
(1988) - et al.
Diaphragmatic energy expenditure in chronic respiratory failure
Am J Med
(1977) - et al.
Ventilatory and diaphragmatic EMG changes during negative pressure ventilation in healthy subjects
J Appl Physiol
(1988)
Ventilatory and diaphragmatic EMG responses to negative pressure ventilation in airflow obstruction
J Appl Physiol
Inhibition of inspiratory muscle activity during sleep: chemical and nonchemical influences
Am Rev Respir Dis
Cited by (25)
Randomized Crossover Study of Lung Expansion Therapy Using Negative Pressure and Positive Pressure in Bronchiectasis
2012, Journal of Experimental and Clinical MedicineCitation Excerpt :Previous studies of NPV using dynamic CT suggested that the lung distension achieved with negative pressure is characterized by a greater proportion of normally aerated lung (with less atelectasis) during inspiration and at end-expiration, resulting in superior oxygenation.9 The earlier finding on higher levels of tidal volume associated with NPV could explain the reduction in the use of accessory muscles and the increase in FVC.10,20 The excessive airway secretion in patients with bronchiectasis is one indication for therapy with NPV.21,22
Effects of intermittent negative pressure ventilation on effective ventilation in normal awake subjects
2002, ChestCitation Excerpt :Whereas the disappearance of EMGdi resulted in a glottic narrowing, increases in INP did not result in our study in a further glottic narrowing: 31.2 ± 7.4° for step F15-P15 and 36.5 ± 8.2° for step F20-P30. This can well explain the high level of Vt seen during NPV in the present study and in the study of Nava et al.40 Glottic narrowing can be favored by inhibition of the inspiratory activity of the respiratory centers, as during nasal IPPV. However, a reflex abduction of the vocal cords during negative pressure application in the upper airway might counterbalance the tendency of the glottis to narrow43 and could explain our results.