Factors Influencing of Pulse Pressure Variation (PPV)

Study Overview
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Brief Summary
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The investigators studied the predictive value of PPV in the patients with different influencing factors;and the method to improve the predictive value,which can improve the application of PPV in ICU.

Detailed Description
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PPV can be used to predict fluid responsiveness in patients with circulatory shock.However, it is affected by many factors, which leads to the decrease of the applicability of PPV in ICU.Therefore, the investigators studied the predictive value of PPV in the patients with different influencing factors;and the method to improve the predictive value,which can improve the application of PPV in ICU.

Official Title
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Factors Influencing the Reliability of Pulse Pressure Variation (PPV) as a Predictor of Fluid Responsiveness in Mechanically Ventilated Patients

Conditions
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Fluid Responsiveness, Pulse Pressure Variation, Haemodynamics

Intervention / Treatment
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* Device: Patients were ventilated with assist-control ventilation（A/C） mode at different tidal volume
* Behavioral: spontaneous breathing and no spontaneous breathing


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients requiring invasive mechanical ventilation Acute circulatory failure,defined as:systolic blood pressure <90 mmHg or blood pressure in patients with previous hypertension lower than the baseline value> 40 mmHg; vasoactive drugs are required to maintain blood pressure (mean arterial pressure> 65 mmHg); with or without signs of hypoperfusion (oliguria<0.5ml.kg-1.h-1 for at least 2 hours; arterial blood lactic acid>2.5mmol.L-1; skin mottling) Exclusion Criteria: The age of the patient is less than 18 years old or more than 80 years old Refuse to sign the informed consent to join the group Atrial fibrillation and other arrhythmias that seriously affect the output per beat; With pregnancy Other situations where the clinician believes that the patient is not suitable for inclusion in the study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Circulatory failure patients<br>Circulatory failure patients requiring fluid responsiveness evaluation | Device: Patients were ventilated with assist-control ventilation（A/C） mode at different tidal volume<br>* Ventilation mode was set to assist-control volume ventilation with different tidal volume, respiratory frequency 15 times/min, PEEP 5 centimeter water column.<br>Behavioral: spontaneous breathing and no spontaneous breathing<br>* Data were recorded when patients had and did not have spontaneous breathing<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| cardiac output(CO) | The measurement of cardiac output(CO); | 1 day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| measurement of Hemodynamic variables from the monitor; | The investigators record the hemodynamic variables from the monitor MAP and CVP | 1 day | 
| measurement of Pulse pressure variation（PPV）from monitor; | Pulse pressure variation (PPV)(percent) ,whic is calculated from the systolic and diastolic blood pressure,can be read from the monitor directly. | Research period | 
| measurement of airway pressure variables from ventilator | The investigators record the airway pressure variables during the inspiration and expiration from the ventilator | 1 day | 
| P 0.1 | airway occlusion pressure at 100 milliseconds after the onset of inspiration (P0.1)(cmH2O) | 1 day | 
| Pocc | delta change of airway pressure during expiratory occlusion in different interventions. | 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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haemodynamics;, Pulse pressure variation;, fluid responsiveness;, Mechanical ventilation;