Ignite Creation Date:
2024-05-06 @ 3:26 AM
Last Modification Date:
2024-10-26 @ 11:34 AM
Study NCT ID:
NCT02292888
Status:
UNKNOWN
Last Update Posted:
2014-11-18
First Post:
2014-11-13
Brief Title:
Can Changes in Velocity Time Integral Serve as a Sensitive Indicator for Monitoring Changes in Stroke Volume
Sponsor:
Fortis Hospital India
Organization:
Fortis Hospital India
Study Overview
Official Title:
Can Changes in LVOT VTI Before and After Passive Leg Raising PLR Test Serve as a Sensitive Indicator for Changes in SV and CO and Hence Volume Responsiveness
Status:
UNKNOWN
Status Verified Date:
2014-11
Last Known Status:
NOT_YET_RECRUITING
Delayed Posting:
No
If Stopped, Why?:
Not Stopped
Has Expanded Access:
False
If Expanded Access, NCT#:
N/A
Has Expanded Access, NCT# Status:
N/A
Acronym:
None
Brief Summary:
Hypothesis A validated technique to measure cardiac output CO using echocardiography is to calculate stroke volume from the product of LVOT area and LVOT VTI and multiplying the product with heart rate CO SV x HR SV LVOT area x LVOT VTI
The LVOT diameter for an individual is more or less a constant measurement Therefore using the formula mentioned above SV LVOT area x LVOT VTI if the LVOT area is constant then SV should be proportional to the VTI This means if a PLR manoeuvre or fluid bolus helps to achieve a rise in SV then it should be reflected in an increase in VTI as well If this assumption is true then an increase in the value of VTI from baseline after fluid challenge 10-15 should identify a volume responsive patient
The LVOT diameter for an individual is more or less a constant measurement Therefore using the formula mentioned above SV LVOT area x LVOT VTI if the LVOT area is constant then SV should be proportional to the VTI This means if a PLR manoeuvre or fluid bolus helps to achieve a rise in SV then it should be reflected in an increase in VTI as well If this assumption is true then an increase in the value of VTI from baseline after fluid challenge 10-15 should identify a volume responsive patient
Detailed Description:
Can changes in LVOT VTI before and after passive leg raising PLR test serve as a sensitive indicator for changes in SV and CO and hence volume responsiveness
What is Doppler LVOT VTI Placing a Pulsed Wave Doppler gate on the LVOT immediately below the opening of the aortic valve while aligning the Doppler beam as parallel to the LVOTaortic axis as possible with an angle of Doppler alignment 20 one may obtain Doppler flow velocity measurements which can help measure the LVOT VTI Velocity Time Integral If one integrates this velocity profile between two time points ie calculates the area under the curve the distance traversed of a region of blood flowing during this period may be estimated Since flow velocity is not constant throughout a flow cycle all of the flow velocities during the entire ejection period is integrated to measure distance traversed of this region of blood This integration of flow velocities in a given period of time is called the velocity-time integral VTI1 and yields length or distance measured in cm
Goal Whether VTI LVOT measured from the deep transgastric deep TG or transgastric long axis TG LAX views reflect changes in stroke volumeSV and hence cardiac output CO measured by the gold standard method PA CCO by thermodilution before and after passive leg raising test PLR
Hypothesis A validated technique to measure cardiac output CO using echocardiography is to calculate stroke volume from the product of LVOT area and LVOT VTI and multiplying the product with heart rate CO SV x HR SV LVOT area x LVOT VTI
The LVOT diameter for an individual is more or less a constant measurement Therefore using the formula mentioned above SV LVOT area x LVOT VTI if the LVOT area is constant then SV should be proportional to the VTI This means if a PLR manoeuvre or fluid bolus helps to achieve a rise in SV then it should be reflected in an increase in VTI as well If this assumption is true then an increase in the value of VTI from baseline after fluid challenge 10-15 should identify a volume responsive patient
Why do the investigators wish to do the study A significant improvement in the field of anesthesiology would occur if we could have a simple yet accurate relatively non-invasive tool to correctly assess fluid responsiveness Excessive fluid infused in the operating room would prolong mechanical ventilation and stay in the ICU and negatively affect the prognosis of the patient While monitoring with CCO PA catheter considerable adds to the expense it has its own complications and as may not be indicated in majority of operative cases A simple non invasive tool using TEE can significantly add to our understanding of hemodynamics and help guide fluid therapy If our assumption proves to be correct then it could be a simple yet rapid bedside indicator of CO It could be used as a simple tool to assess fluid responsiveness
The fundamental reason why a fluid challenge PLR or fluid boluses is used is to assess whether there is an increase stroke volume in response to it 2 If the fluid loading fails to improve the stroke volume the fluid challengeloading serves no useful purpose In normal physiological conditions both the ventricles operate on the ascending limb of the Frank-Starling curve Once the left ventricle starts functioning on the flat portion of the Frank-Starling curve fluid loading has little or no effect on stroke volume If LVOT VTI could be shown to reflect SV adequately then it will be a relatively simple non invasive dynamic bedside tool to test if fluid boluses are resulting in an increase in VTI hence the SV
Volume responsiveness has been assessed in literature by measuring the response to fluid boluses or to PLR Thus a positive test where after a PLR VTI increased significantly reflecting a positive change in SV and CO more fluid would be required Whereas if during PLR CO and SV diminished reflected by a decrease in the VTI value compared to baseline the subject would be unlikely to respond to fluid therapy and probably would require inotropic support
Why PLR A recent meta-analysis 3 which pooled the results of eight recent studies confirmed the excellent value of PLR to predict fluid responsiveness in critically ill patients with a global area under the receiver operating characteristic curve of 095
Limitations of using Doppler VTI However use of these equations entails a number of assumptions including a laminar blood flow in the area interrogated b a flat or blunt flow velocity profile such that the flow across the entire CSA interrogated is relatively uniform and c Doppler angle of incidence between the Doppler beam and the main direction of blood flow is less than 20 degrees so that the underestimation of the flow velocity is less than 6
Study population 50 adult patients undergoing coronary artery bypass surgery Materials Methods After institutional ethics committee approval and personal informed consent 50 patients undergoing elective coronary artery bypass surgery would be included into the study Patients with significant arrhythmias concomitant aortic aneurysms and esophageal pathology precluding the use of TEE would be considered ineligible for the study
Patients would be divided into two groups Patients with normal LV function or mild LV systolic dysfunction LVEF 404 assessed by preoperative echocardiography would comprise Group 1 whereas those with preoperative LV moderate to severe systolic dysfunction LVEF 404 would be designated to Group 2
Anesthetic protocol Patients would be fasted for 8 hours preceding the operation No iv fluids would be administered during this period Patients would be pre-medicated with their usual cardiovascular medication and 1mg of Lorazepam the night before and would receive 1-2 mg of Midazolam at arrival to the operation theatre After initiating standard monitoring ECG Pulse oximetry NBP invasive lines would be introduced under local anesthetic infiltration while the patient would receive supplemental oxygen via facemask Induction of anesthesia would include 005 mg kg_1 Midazolam and 5 mcg kg_1 Fentanyl in addition to Sevoflurane 3-5 titrated to loss of eyelash reflex Tracheal intubation would be facilitated by Rocuronium 01 mg kg_1 Anaesthesia would be maintained by Sevoflurane 15-2 titrated to an end tidal value of 15and above supplemented by additional doses of fentanyl up to a total dose of 15-20 mg kg_1 All patients would receive 500 ml of lactated Ringer solution during the induction period
Hemodynamic and Echocardiographic monitoring A 70Fr triple lumen central line a 85 Fr PA sheath and 70 Fr CCO Continuous Cardiac Output PA catheter and a 16 G femoral arterial canula would be introduced prior to induction of anesthesia under light sedation and local anesthesia A Philips HD 11XE ultrasound machine Andover USA and transesophageal multiplane echocardiographic probe would be used in all patients After a comprehensive TEE examination the probe would be positioned to record images from either a deep TG or TGLAX views Images would be recorded for off-line evaluation A Board certified echocardiographer proficient in TEE would perform all echocardiographic measurements Offline echocardiographic measurements would be done by a trained echocardiographer who would be blinded to the study protocol All hemodynamic measurements will be recorded by a dedicated research nurse
Experimental protocol After the induction of anesthesia and initiation of hemodynamic monitoring the patients would be stabilized as necessary and observed for 10-15 min No further interventions would be allowed during this period including further fluid administration changes in anesthetic concentrations or manipulations with inotropic or vasoconstrictor concentrations A period of at least 5 min of stable BP heart rate CVP and continuous cardiac output would be required before obtaining the baseline set of hemodynamic measurements A passive leg raising PLR maneuver 45 using protocol described before in literature would be performed and changes in hemodynamic and echocardiographic parameters would be measured within 1 minute post PLR The same sequence of PLR and echocardiographic and hemodynamic measurements would be repeated after the end of the operation and before the transfer to the ICU No measurements would be carried out in the presence of hemodynamic instability or immediately following changes of inotropic or anesthetic medications
The first set of measurements HR MAP VTI SV CO LVEF and LVOT area would be obtained in the semi-recumbent position 45 designated baseline Then the lower limbs would be lifted while straight 45 with the trunk lowered in the supine position The second set of measurements of designated during PLR was obtained during leg elevation at the moment when VTI plateaued at its highest value The stroke volume with CCO monitor would be recorded at the moment when it plateaued at its highest value
NB Why record changes in VTISV etc within 1 minute post PLR Because the maximal hemodynamic effects of PLR occur within the first minute of leg elevation it is important to assess these effects with a method that is able to track changes in cardiac output or stroke volume on a real-time basis5
NB Passive leg raising The passive leg raising test consists in measuring the hemodynamic effects of a leg elevation up to 45 A simple way to perform the postural maneuver is to transfer the patient from the semirecumbent posture to the passive leg raising position by using the automatic motion of the bed
What is Doppler LVOT VTI Placing a Pulsed Wave Doppler gate on the LVOT immediately below the opening of the aortic valve while aligning the Doppler beam as parallel to the LVOTaortic axis as possible with an angle of Doppler alignment 20 one may obtain Doppler flow velocity measurements which can help measure the LVOT VTI Velocity Time Integral If one integrates this velocity profile between two time points ie calculates the area under the curve the distance traversed of a region of blood flowing during this period may be estimated Since flow velocity is not constant throughout a flow cycle all of the flow velocities during the entire ejection period is integrated to measure distance traversed of this region of blood This integration of flow velocities in a given period of time is called the velocity-time integral VTI1 and yields length or distance measured in cm
Goal Whether VTI LVOT measured from the deep transgastric deep TG or transgastric long axis TG LAX views reflect changes in stroke volumeSV and hence cardiac output CO measured by the gold standard method PA CCO by thermodilution before and after passive leg raising test PLR
Hypothesis A validated technique to measure cardiac output CO using echocardiography is to calculate stroke volume from the product of LVOT area and LVOT VTI and multiplying the product with heart rate CO SV x HR SV LVOT area x LVOT VTI
The LVOT diameter for an individual is more or less a constant measurement Therefore using the formula mentioned above SV LVOT area x LVOT VTI if the LVOT area is constant then SV should be proportional to the VTI This means if a PLR manoeuvre or fluid bolus helps to achieve a rise in SV then it should be reflected in an increase in VTI as well If this assumption is true then an increase in the value of VTI from baseline after fluid challenge 10-15 should identify a volume responsive patient
Why do the investigators wish to do the study A significant improvement in the field of anesthesiology would occur if we could have a simple yet accurate relatively non-invasive tool to correctly assess fluid responsiveness Excessive fluid infused in the operating room would prolong mechanical ventilation and stay in the ICU and negatively affect the prognosis of the patient While monitoring with CCO PA catheter considerable adds to the expense it has its own complications and as may not be indicated in majority of operative cases A simple non invasive tool using TEE can significantly add to our understanding of hemodynamics and help guide fluid therapy If our assumption proves to be correct then it could be a simple yet rapid bedside indicator of CO It could be used as a simple tool to assess fluid responsiveness
The fundamental reason why a fluid challenge PLR or fluid boluses is used is to assess whether there is an increase stroke volume in response to it 2 If the fluid loading fails to improve the stroke volume the fluid challengeloading serves no useful purpose In normal physiological conditions both the ventricles operate on the ascending limb of the Frank-Starling curve Once the left ventricle starts functioning on the flat portion of the Frank-Starling curve fluid loading has little or no effect on stroke volume If LVOT VTI could be shown to reflect SV adequately then it will be a relatively simple non invasive dynamic bedside tool to test if fluid boluses are resulting in an increase in VTI hence the SV
Volume responsiveness has been assessed in literature by measuring the response to fluid boluses or to PLR Thus a positive test where after a PLR VTI increased significantly reflecting a positive change in SV and CO more fluid would be required Whereas if during PLR CO and SV diminished reflected by a decrease in the VTI value compared to baseline the subject would be unlikely to respond to fluid therapy and probably would require inotropic support
Why PLR A recent meta-analysis 3 which pooled the results of eight recent studies confirmed the excellent value of PLR to predict fluid responsiveness in critically ill patients with a global area under the receiver operating characteristic curve of 095
Limitations of using Doppler VTI However use of these equations entails a number of assumptions including a laminar blood flow in the area interrogated b a flat or blunt flow velocity profile such that the flow across the entire CSA interrogated is relatively uniform and c Doppler angle of incidence between the Doppler beam and the main direction of blood flow is less than 20 degrees so that the underestimation of the flow velocity is less than 6
Study population 50 adult patients undergoing coronary artery bypass surgery Materials Methods After institutional ethics committee approval and personal informed consent 50 patients undergoing elective coronary artery bypass surgery would be included into the study Patients with significant arrhythmias concomitant aortic aneurysms and esophageal pathology precluding the use of TEE would be considered ineligible for the study
Patients would be divided into two groups Patients with normal LV function or mild LV systolic dysfunction LVEF 404 assessed by preoperative echocardiography would comprise Group 1 whereas those with preoperative LV moderate to severe systolic dysfunction LVEF 404 would be designated to Group 2
Anesthetic protocol Patients would be fasted for 8 hours preceding the operation No iv fluids would be administered during this period Patients would be pre-medicated with their usual cardiovascular medication and 1mg of Lorazepam the night before and would receive 1-2 mg of Midazolam at arrival to the operation theatre After initiating standard monitoring ECG Pulse oximetry NBP invasive lines would be introduced under local anesthetic infiltration while the patient would receive supplemental oxygen via facemask Induction of anesthesia would include 005 mg kg_1 Midazolam and 5 mcg kg_1 Fentanyl in addition to Sevoflurane 3-5 titrated to loss of eyelash reflex Tracheal intubation would be facilitated by Rocuronium 01 mg kg_1 Anaesthesia would be maintained by Sevoflurane 15-2 titrated to an end tidal value of 15and above supplemented by additional doses of fentanyl up to a total dose of 15-20 mg kg_1 All patients would receive 500 ml of lactated Ringer solution during the induction period
Hemodynamic and Echocardiographic monitoring A 70Fr triple lumen central line a 85 Fr PA sheath and 70 Fr CCO Continuous Cardiac Output PA catheter and a 16 G femoral arterial canula would be introduced prior to induction of anesthesia under light sedation and local anesthesia A Philips HD 11XE ultrasound machine Andover USA and transesophageal multiplane echocardiographic probe would be used in all patients After a comprehensive TEE examination the probe would be positioned to record images from either a deep TG or TGLAX views Images would be recorded for off-line evaluation A Board certified echocardiographer proficient in TEE would perform all echocardiographic measurements Offline echocardiographic measurements would be done by a trained echocardiographer who would be blinded to the study protocol All hemodynamic measurements will be recorded by a dedicated research nurse
Experimental protocol After the induction of anesthesia and initiation of hemodynamic monitoring the patients would be stabilized as necessary and observed for 10-15 min No further interventions would be allowed during this period including further fluid administration changes in anesthetic concentrations or manipulations with inotropic or vasoconstrictor concentrations A period of at least 5 min of stable BP heart rate CVP and continuous cardiac output would be required before obtaining the baseline set of hemodynamic measurements A passive leg raising PLR maneuver 45 using protocol described before in literature would be performed and changes in hemodynamic and echocardiographic parameters would be measured within 1 minute post PLR The same sequence of PLR and echocardiographic and hemodynamic measurements would be repeated after the end of the operation and before the transfer to the ICU No measurements would be carried out in the presence of hemodynamic instability or immediately following changes of inotropic or anesthetic medications
The first set of measurements HR MAP VTI SV CO LVEF and LVOT area would be obtained in the semi-recumbent position 45 designated baseline Then the lower limbs would be lifted while straight 45 with the trunk lowered in the supine position The second set of measurements of designated during PLR was obtained during leg elevation at the moment when VTI plateaued at its highest value The stroke volume with CCO monitor would be recorded at the moment when it plateaued at its highest value
NB Why record changes in VTISV etc within 1 minute post PLR Because the maximal hemodynamic effects of PLR occur within the first minute of leg elevation it is important to assess these effects with a method that is able to track changes in cardiac output or stroke volume on a real-time basis5
NB Passive leg raising The passive leg raising test consists in measuring the hemodynamic effects of a leg elevation up to 45 A simple way to perform the postural maneuver is to transfer the patient from the semirecumbent posture to the passive leg raising position by using the automatic motion of the bed
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
None
Is a FDA Regulated Device?:
None
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None