Spectral Analysis of Central Venous Pressure Waveform

Study Overview
=================
Brief Summary
-----------------
The use of central venous pressure has been abandoned for the assessment of intravascular volume status. The dynamic fluctuation of central venous pressure according to heart rate is quantitatively measured by spectral analysis of the central venous pressure waveform. Its clinical utility in the assessment of intravascular volume status is investigated.

Detailed Description
-----------------
The use of central venous pressure, which is one of the static preload indices, has been abandoned for the assessment of intravascular volume status because of its unreliability. The static preload indices have been replaced with dynamic preload indices, such as stroke volume variation or pulse pressure variation because the dynamic preload indices reliably predict fluid responsiveness and perform better than the static preload indices. However, the periodic component of central venous pressure, which goes with cardiac cycles, has not been investigated. The power corresponding to heart rate from spectral analysis of central venous pressure waveform represents the extent of the dynamic fluctuation of central venous pressure and is assumed to reflect intravascular volume status. It is hypothesized that the spectral power of central venous pressure corresponding to heart rate represents intravascular volume status.

Official Title
-----------------
Spectral Analysis of Central Venous Pressure Waveform in Patients Undergoing Donor Hepatectomy

Conditions
-----------------
Donor Hepatectomy, Central Venous Catheter, Hypovolemia

Intervention / Treatment
-----------------
* Procedure: Placement of a central venous catheter
* Device: Monitoring of central venous pressure
* Drug: Furosemide-induced hypovolemia before graft procurement
* Drug: Replacement of fluid loss after graft procurement
* Device: Monitoring of stroke volume variation


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: American Society of Anesthesiologists physical status 1 Scheduled for donor hepatectomy under general anesthesia Exclusion Criteria: Arrhythmia Valvular heart disease Coronary artery disease Cerebrovascular disease Hypertension Diabetes mellitus Renal insufficiency Pulmonary problems Any type of liver disease Body mass index greater than 35 kg/m2 Human immunodeficiency virus infection Psychosocial problems Electrolyte imbalance Reoperation

Ages Eligible for Study
-----------------
Minimum Age: 20 Years
Maximum Age: 60 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Donor hepatectomy<br>Live donors undergoing hepatectomy | Procedure: Placement of a central venous catheter<br>* The right internal jugular vein is located at the first rib level under ultrasound-guidance. Using an out-of-plane technique, a needle is introduced into the lumen of the vessel. The aspiration of blood into the syringe connected to the hub of the needle confirms the placement of the needle tip in the lumen. After the syringe is detached from the needle, a guidewire is advanced into the vessel lumen through the needle. A dilator is introduced over the guidewire and subsequently is removed. Then, a central venous catheter is introduced over the guidewire into the vessel lumen through the pathway expanded by the dilator. The catheter tip is placed in the superior vena cava by inserting the catheter as far as the distance between the edge of the right transverse process of the first thoracic vertebra and the carina, which is preoperatively measured on a posteroanterior chest radiograph.<br>Device: Monitoring of central venous pressure<br>* Following the placement of a central venous catheter, a fluid-filled system for monitoring central venous pressure is connected to the proximal lumen of the catheter. The reference transducer is placed at the level of 4/5 of the anteroposterior diameter of the thorax.<br>Drug: Furosemide-induced hypovolemia before graft procurement<br>* Patients fast from 10 pm the day before surgery. On the arrival at the operating room, an intravenous catheter for Plasmalyte infusion is placed into the right cephalic or basilic vein. The distal lumen of the central venous catheter is used for the infusion of 6% hydroxyethyl starch. Fluid requirements due to anesthesia, surgery, and no per os intake are not replaced by minimizing the administration of the fluids. Five minutes after the collection of the baseline data, 20 mg of furosemide is administered to promote diuresis for facilitating the venous outflow of the liver. An additional dose of furosemide 20 mg is given if the urine output is <1 ml/kg within 30 minutes after the first dose. Unless the second dose of furosemide produces >1 ml/kg of urine within 30 minutes, 40 mg of furosemide is administered. In the absence of effective diuresis (1 ml/kg within 30 minutes after each dose), the use of furosemide is abandoned and the patients are excluded from the study.<br>Drug: Replacement of fluid loss after graft procurement<br>* Immediately after the graft procurement, 500 ml of 6% hydroxyethyl starch are infused over 25 minutes. Afterward, Plasmalyte is infused at a rate of 10 ml/min until the end of surgery.<br>Device: Monitoring of stroke volume variation<br>* Following anesthesia induction, the right radial artery is catheterized. The catheter is connected to the EV1000 monitor (Edwards Lifesciences, Irvine, CA) through the FloTrac transducer (Edwards Lifesciences). The transducer is level with the one for central venous pressure monitoring. Using pulse contour analysis without external calibration, the stroke volume for each heartbeat is measured. At a 20-second interval, stroke volume variation is calculated as (maximum stroke volume - minimum stroke volume)/mean stroke volume.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Spectral power of central venous pressure corresponding to heart rate during 5 minutes before graft procurement | A band-pass filter (0.15-3 Hz) is applied to the 5 minute-long segment. The 5 minute-long segments are divided into 100 second-long segments overlapping 50% with each adjacent segment. Each segment is submitted to fast Fourier transformation. The spectral powers obtained from the periodograms of each segment are averaged. The integrated area corresponding to heart rate is the spectral power corresponding to heart rate. | During 5 minutes before graft procurement | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Spectral powers of central venous pressure corresponding to respiratory rate and heart rate during 5 minutes before the first dose of furosemide | A band-pass filter (0.15-3 Hz) is applied to the 5 minute-long segment. The 5 minute-long segments are divided into 100 second-long segments overlapping 50% with each adjacent segment. Each segment is submitted to fast Fourier transformation. The spectral powers obtained from the periodograms of each segment are averaged. The integrated areas corresponding to respiratory rate and heart rate are the spectral powers corresponding to respiratory rate and heart rate. | During 5 minutes before the first dose of furosemide | 
| Spectral powers of central venous pressure corresponding to respiratory rate and heart rate between 30 and 35 minutes after surgical incision | A band-pass filter (0.15-3 Hz) is applied to the 5 minute-long segment. The 5 minute-long segments are divided into 100 second-long segments overlapping 50% with each adjacent segment. Each segment is submitted to fast Fourier transformation. The spectral powers obtained from the periodograms of each segment are averaged. The integrated areas corresponding to respiratory rate and heart rate are the spectral powers corresponding to respiratory rate and heart rate. | Between 30 and 35 minutes after surgical incision | 
| Spectral power of central venous pressure corresponding to respiratory rate during 5 minutes before graft procurement | A band-pass filter (0.15-3 Hz) is applied to the 5 minute-long segment. The 5 minute-long segments are divided into 100 second-long segments overlapping 50% with each adjacent segment. Each segment is submitted to fast Fourier transformation. The spectral powers obtained from the periodograms of each segment are averaged. The integrated area corresponding to respiratory rate is the spectral power corresponding to respiratory rate. | During 5 minutes before graft procurement | 
| Spectral powers of central venous pressure corresponding to respiratory rate and heart rate during 5 minutes after administration of 6% hydroxyethyl starch | A band-pass filter (0.15-3 Hz) is applied to the 5 minute-long segment. The 5 minute-long segments are divided into 100 second-long segments overlapping 50% with each adjacent segment. Each segment is submitted to fast Fourier transformation. The spectral powers obtained from the periodograms of each segment are averaged. The integrated areas corresponding to respiratory rate and heart rate are the spectral powers corresponding to respiratory rate and heart rate. | During 5 minutes after administration of 6% hydroxyethyl starch | 
| Stroke volume variation during 5 minutes before the first dose of furosemide | The median of the values calculated at a 20-second interval | During 5 minutes before the first dose of furosemide | 
| Stroke volume index during 5 minutes before the first dose of furosemide | The median of the values calculated at a 20-second interval | During 5 minutes before the first dose of furosemide | 
| Cardiac index during 5 minutes before the first dose of furosemide | The median of the values calculated at a 20-second interval | During 5 minutes before the first dose of furosemide | 
| Stroke volume variation between 30 and 35 minutes after surgical incision | The median of the values calculated at a 20-second interval | Between 30 and 35 minutes after surgical incision | 
| Stroke volume index between 30 and 35 minutes after surgical incision | The median of the values calculated at a 20-second interval | Between 30 and 35 minutes after surgical incision | 
| Cardiac index between 30 and 35 minutes after surgical incision | The median of the values calculated at a 20-second interval | Between 30 and 35 minutes after surgical incision | 
| Stroke volume variation during 5 minutes before graft procurement | The median of the values calculated at a 20-second interval | During 5 minutes before graft procurement | 
| Stroke volume index during 5 minutes before graft procurement | The median of the values calculated at a 20-second interval | During 5 minutes before graft procurement | 
| Cardiac index during 5 minutes before graft procurement | The median of the values calculated at a 20-second interval | During 5 minutes before graft procurement | 
| Stroke volume variation during 5 minutes after administration of 6% hydroxyethyl starch | The median of the values calculated at a 20-second interval | During 5 minutes after administration of 6% hydroxyethyl starch | 
| Stroke volume index during 5 minutes after administration of 6% hydroxyethyl starch | The median of the values calculated at a 20-second interval | During 5 minutes after administration of 6% hydroxyethyl starch | 
| Cardiac index during 5 minutes after administration of 6% hydroxyethyl starch | The median of the values calculated at a 20-second interval | During 5 minutes after administration of 6% hydroxyethyl starch | 
| Total dose of furosemide | The total dose of furosemide used for the promotion of diuresis | At graft procurement | 
| Urine output at graft procurement | The total amount of urine output between the placement of urinary catheter and graft procurement | At graft procurement | 
| Total urine output at the end of surgery | The total amount of urine output at the end of surgery | At the end of surgery | 
| Intraoperative blood loss | Calculated as blood loss (ml) = [estimated blood volume*(preoperative hematocrit-postoperative hematocrit)]/mean between the 2 hematocrit values, where estimated blood volume (ml) = weight(kg)^0.425*height(cm)^0.725*0.007184*2217+age(years)*1.06 for female and weight(kg)^0.425*height(cm)^0.725*0.007184*3064-825 for male | 1 day after surgery |