A Functional Test to Assess Fluid Status During Lung Protective Ventilation Strategies

Study Overview
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Brief Summary
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Dynamic preload indices, such as pulse pressure variation (PPV) and stroke volume variation (SVV) are generally accepted as accurate indicator of fluid responsiveness in mechanically ventilated patients. Because SVV and PPV are generated by the pressure transmitted from the airways to the pleural and pericardial spaces, their reliability is limited in patients receiving low tidal volume (VT) ventilation and in those with a driving pressure lower than 20 cm H2O. Lung-protective ventilation using low VT with positive end expiratory pressure (PEEP) has recently been demonstrated to significantly improve postoperative outcome, and its application is gradually increasing in surgical patients. However, protective ventilation alters the predictability of dynamic preload indices and thus limits their use in the operating theatre. Lung recruitment maneuvers (LRMs), used to reopen collapsed lung, and PEEP have been proposed as the key components of lung-protective ventilation strategy. LRM increases intrathoracic pressure, which in turn causes a transient decrease in stroke volume (SV) and arterial pressure; this may depend on preload status. Interestingly, recent study reported that the augmented PPV during LRM using vital capacity maneuver (VCM, continuous positive airway pressure of 30 cm H2O for 10 s) could predict preload responsiveness under open chest condition. Investigators hypothesized that the augmented PPV and SVV by a stepwise LRM with incremental PEEP could represent a functional test to suggest preload responsiveness and, therefore, predict fluid responsiveness. The aims of the current study were (1) to assess the ability of augmented PPV and SVV during stepwise LRM-induced to predict fluid responsiveness in mechanically ventilated patients in the operating room, (2) to assess the ability of stepwise LRM-induced decrease in SV (ΔSV-LRM) to predict fluid responsiveness.

Official Title
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Development of a Functional Test to Assess Fluid Status During Lung Protective Ventilation Strategies in the Operating Room.

Conditions
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Patients Receiving Protective Lung Ventilation, Patients in Grey Zone (3 < Pulse Pressure Variation (PPV) < 17

Intervention / Treatment
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* Diagnostic Test: lung recruitment maneuver


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients receiving laparotomy and lung protective ventilation Exclusion Criteria: preoperative arrhythmia Severe bradycardia Moderate to severe valvular disease left ventricular ejection fraction < 50% Poorly controlled hypertension (systolic BP > 160 mmHg) Patients with renal insufficiency (creatinine > 1.5 mg/dL) Moderate to severe liver disease BMI >.30 or < 15 kg/ m2 preexisting pulmonary disease FEV1 < 60% of predicted value

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Diagnostic Test: lung recruitment maneuver|The ventilator was switched to pressure control ventilation, inspiratory time was increased to 50%, the peak inspiratory pressure gradient (above PEEP) was set at 15cm H2O, and PEEP was progressively increased to obtain a stepwise increase of peak inspiratory to 20, 25, and 30 cm H2O every three breaths. The final recruiting pressure of 30 cm H2O was applied for six breaths.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PPV_augmented | augmented pulse pressure variation by lung recruitment maneuver | During the last 5 second of lung recruitment maneuver | 
| SVV_augmented | augmented stroke volume variation by lung recruitment maneuver | During the last 5 second of lung recruitment maneuver | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| ΔSV_LRM | The degree of reduction of stroke volume induced by lung recruitment maneuver | During the last 5 second of lung recruitment maneuver | 
| ΔETCO2_LRM | The degree of reduction of end tidal CO2 concentration induced by lung recruitment maneuver | During the last 5 second of lung recruitment maneuver |