Effects of Inspiratory Flow Waveforms on Preload
The clinical usefulness of inspiratory flow pattern manipulation during mechanical ventilation remains unclear. The aim of this study was to investigate the effects of different inspiratory flow waveforms, i.e. constant and decelerating, on cardiac preload in mechanically ventilated patients assessed by arterial pulse pressure variation (PPV) and inferior vena cava distensibility.
|Study Design:||Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Supportive Care
|Official Title:||Effects of Inspiratory Flow Waveforms on Arterial Pulse Pressure Variation and Inferior Vena Cava Distensibility in Mechanically Ventilated Patients.|
- change in pulse pressure variation (ΔPP) and distensibility index of the inferior vena cava (dIVC)when varying inspiratory flow waveforms [ Time Frame: 2h ] [ Designated as safety issue: No ]Each inspiratory flow waveform was maintained for 30 min with 60 minutes washout period
|Study Start Date:||May 2013|
|Estimated Study Completion Date:||August 2013|
|Estimated Primary Completion Date:||July 2013 (Final data collection date for primary outcome measure)|
mechanically ventilated patients
patients admitted to a 18-bed medical surgical intensive care unit of the military hospital of Tunisia and were mechanically ventilated fully adapted to their ventilator and in sinus rhythm.
intervention:varying inspiratory flow waveforms
Device: varying inspiratory flow waveforms
inspiratory flow waveform was changed, in a randomized sequence using a computer ,to one of the following modalities: 1) constant inspiratory flow; 2) decelerating inspiratory flow Each inspiratory flow waveform was maintained for 30 min. During the last 5 min of this period the physiological signals were collected and measures were performed.
During mechanical ventilation the lungs can be inflated with different pressure and flow waveforms. Originally the piston-driven mechanical ventilators generated a quasi-sinusoidal flow waveform, whereas the newer electronically controlled ventilators can also produce constant and decelerating waveforms. According to several theoretical,animal and clinical studies,the inspiratory flow waveform affects the distribution of the inspired gas as well as respiratory mechanics and gas exchange. However, other studies failed to show any significant effect.But there is no study interested to the effects of inspiratory flow waveforms on cardiac preload. Thus, the clinical usefulness of inspiratory flow pattern manipulation remains unclear, though the capacity for selection of different inspiratory flow waveforms is provided by most modern, microprocessor-equipped ventilators. Therefore, the purpose of this study was to compare the effects of flow patterns (sinusoidal, constant and decelerating) on dynamic measurements of cardiac preload dependence such as arterial pulse pressure variation (ΔPP) and distensibility index of the inferior vena cava (dIVC).
|Contact: zied hajjej, Drfirstname.lastname@example.org|
|Military hospital of tunis||Recruiting|
|Tunis, Mont Fleury, Tunisia, 1008|
|Contact: zied hajjej, Dr +21620358907 email@example.com|
|Principal Investigator: zied hajjej, dr|
|Principal Investigator:||zied hajjej, Dr||Military Hospital of Tunis|