Cardiac Output, Low
Conditions
Keywords
inspiratory flow pattern, mechanical ventilation, cardiac preload, arterial pulse pressure variation, inferior vena cava collapsibility
Brief summary
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.
Detailed description
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).
Interventions
DEVICEvarying 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.
Sponsors
Military Hospital of Tunis
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
SUPPORTIVE_CARE
Masking
NONE
Eligibility
Sex/Gender
ALL
Healthy volunteers
No
Inclusion criteria
* mechanical ventilation * Volume AssistControl Ventilation * sinus rhythm
Exclusion criteria
* pressure mode * arrhythmia
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| change in pulse pressure variation (ΔPP) and distensibility index of the inferior vena cava (dIVC)when varying inspiratory flow waveforms | 2h | Each inspiratory flow waveform was maintained for 30 min with 60 minutes washout period |
Countries
Tunisia
Outcome results
None listed