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Pressure support ventilation (PSV) is the most commonly used mode in mechanical ventilated patients. Studies have shown that over-assistance was prevalent in patients undergoing PSV. Up to now, no reliable method has been recommended to select an "optimal" inspiratory support level. Pressure muscle index (PMI) was introduced recently to evaluate the degree of spontaneous breathing effort. We hypothesize that PMI might be used as an indicator for over-assistance during PSV. In this randomized crossover study, inspiratory support is set at three levels according to negative, positive and zero PMI. Inspiratory effort, work of breathing, and respiratory mechanics are compared among the three inspiratory pressure support levels.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Inspiratory support level with PMI equal to -2 | Experimental | PMI represents the difference between plateau airway pressure and peak airway pressure (plateau - peak) during an end-inspiratory airway occlusion. |
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| Inspiratory support level with PMI equal to 0 | Experimental | PMI represents the difference between plateau airway pressure and peak airway pressure (plateau - peak) during an end-inspiratory airway occlusion. |
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| Inspiratory support level with PMI equal to +2 | Experimental | PMI represents the difference between plateau airway pressure and peak airway pressure (plateau - peak) during an end-inspiratory airway occlusion. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Inspiratory support level | Procedure | Inspiratory support is the pressure delivered by the ventilator during pressure support ventilation. |
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| Measure | Description | Time Frame |
|---|---|---|
| Inspiratory effort | Inspiratory effort is measured as pressure generated by inspiratory muscles using esophageal pressure monitoring. | 30 minutes |
| Work of breathing | Work of breathing is measured by the Campbell diagram and pressure-time-product using esophageal pressure monitoring. | 30 minutes |
| Measure | Description | Time Frame |
|---|---|---|
| Respiratory system compliance (ml/cmH2O) | Respiratory system compliance is calculated as the ratio between tidal volume and driving pressure. | 30 minutes |
| Partial pressure of oxygen in arterial blood (mmHg) |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Jian-Xin Zhou, MD | Contact | 8610 59978019 | zhoujx.cn@icloud.com |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| China-Japan Friendship Hospital | Recruiting | Beijing | Beijing Municipality | 100029 | China |
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| ID | Term |
|---|---|
| D055370 | Lung Injury |
| ID | Term |
|---|---|
| D008171 | Lung Diseases |
| D012140 | Respiratory Tract Diseases |
| D013898 | Thoracic Injuries |
| D014947 | Wounds and Injuries |
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Partial pressure of oxygen in arterial blood is obtained by blood gas analysis.
| Partial pressure of oxygen in arterial blood |
| Partial pressure of carbon dioxide in arterial blood (mmHg) | Partial pressure of carbon dioxide in arterial blood is obtained by blood gas analysis. | 30 minutes |
| Respiratory rate (breaths/min) | Respiratory rate calculation includes ineffective trigger. | 30 minutes |
| Tidal volume (ml) | Tidal volume is obtained by intergation of flow-time tracing. | 30 minutes |
| Rapid shallow breathing index | Rapid shallow breathing index is calculated as the ratio between respiratory rate and tidal volume. | 30 minutes |
| The use of accessory respiratory muscle | The use of accessory respiratory muscle is observed at the bedside. | 30 minutes |
| Beijing Tiantan Hospital | Recruiting | Beijing | Beijing Municipality | 100070 | China |
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