Best-Practices to Achieve Quality Pressure-Volume Loop Data

Best-Practices to Achieve Quality PV Loop Data

1. Equipment Requirements, Operation, & Sanity Checks (Peter Plouf)

2. Volume Calibration Considerations (Peter Plouf)

3. Surgical Considerations – Rodent non-survival applications (Filip Konecny)

• Anesthesia, Analgesia, Ventilation • Monitoring Physiology (HR, BT, RR, and ECG)

4. Optimizing Pressure-Volume Signals (Filip Konecny)

• Catheter Placement • Validating good “baseline data”

5. Q&A Session (Peter Plouf & Filip Konecny)

InsideScientific is an online educational environment designed for life science researchers. Our goal is to aid in

the sharing and distribution of scientific information regarding innovative technologies, protocols, research

tools and laboratory services.

Pressure-Volume Equipment, Operation, and Considerations for Volume Calibration

Peter Plouf

Director of R&D – Scisense Products

Transonic

Copyright 2015 InsideScientific & Transonic. All Rights Reserved.

“Be confident in the data you collect when you collect it.”

THE PURPOSE OF THIS SECTION IS TO PRESENT A SERIES OF “BEST

PRACTICES” THAT WILL EVOKE CONFIDENCE IN YOUR PV LOOP DATA

WHILE YOU ARE COLLECTING IT.

WHEN FOLLOWED, THE SANITY CHECKS PRESENTED WILL PREVENT

THE RESEARCHER FROM COLLECTING INNACURATE DATA

Tools & Equipment List

1. PV System, Data Acquisition System, & PV Catheter

Tip: Read the manuals. Call us for help if needed…

Click for Equipment Information

Tools & Equipment List

2. Ventilator

Tip: use them! But remember, one size does not fit all…

Tools & Equipment List

3. Vaporizer & Appropriate Anesthesia Kit

Tip: consistent delivery and control of anaesthesia is just as important as the type of anesthesia being used

Tools & Equipment List

4. Surgical Tools

Tip: when using catheters smaller than 2F, handle them with padded forceps. Or, regular forceps covered with PE tubing

Tools & Equipment List

5. Microscope for mouse & other small rodents

Tip: use a microscope for better view of the insertion point, and to have better confidence when working with small catheters

Before Starting: System Check

• Data collection relies on a properly set up system consisting of the ADV500, and A/D device and a Data collection software program

• Assuming your system is assembled to the computer and you are familiar with your acquisition system, it is important to make sure your entire system is working and calibrated

• The ADV500 displays high and low calibration values that are used to calibrate the acquisition system

Before starting an experiment, output these values and make sure that the values match

• No matter what data acquisition system and software you are using, the process is the same

• Ensure the low and high values (mmHg, uL, etc.) that correspond with the values provided by the PV System manufacturer

• Pay close attention to the units, and subtle differences between similar animal models (ie. Mouse and Rat)

Emka IOX2

iWorx LabScribe2

ADI LabChart

Notocord Heme

Catheter Selection

• A PV catheter has 4 electrodes and it is important that all 4 be inside of the ventricle

• Single segment catheters are available with segment lengths from 3.5mm (small mouse) all the way to 100mm (large animal)

Tip: If in doubt, err on the side of too short.

Catheter Selection

• Variable Segment Length (VSL) catheters, offering 4 different sensing lengths per catheter, are available to accommodate studies where ventricle size varies

• Available in 1.9F – 7.0F sizes (rat to larger animal)

Rodent Catheter Selection

Segment spacing Species Shaft OD (F)

Recommended Long Axis (mm)

Total Shaft Length (in)

Maximum Volume (µL)

3.5mm Mouse 1.2 5.2 - 5.7 18 150

4.0mm Mouse 1.2 5.7 - 6.2 18 150

4.5mm Mouse 1.2 6.2 - 6.75 18 150

6.0mm Rat 1.9 7.8 - 9.8 18 1000

8.0mm Rat 1.9 9.8 - 11.8 18 1000

10.0mm Rat 1.9 11.8 - 13.8 18 1000

VSL (6, 8, 10, 12 mm) Rat 1.9 8.3 - 15.0 18 1000

VSL (8, 10, 12, 14 mm) Rat 1.9 10.3 - 17.0 18 1500

VSL (8, 11, 14, 17 mm) Rat 1.9 10.3 - 20.0 18 2000

When in doubt, contact us for help!

Balancing Pressure sensor

• Start hydration of the catheter (20 min) prior

• Use a 10 ml syringe with room-temperature saline or PBS

• Use balance controls to reference pressure to zero, while lifting catheter pressure sensor under the meniscus of saline solution

Tip: Correct pressure sensor balancing is key for accurate EDP and ESP measurement

Data Accuracy Comes From Calibration

• PV systems track SV, EF and Contractility.

• Absolute Volume is a mathematically calculated value.

• The calculation is based on three calibration values that the researcher needs to be aware of:

1. Stroke Volume Calibration Factor

2. Blood Resistivity (Rho)

3. Heart Type (Muscle Electrical Property)

1. Stroke Volume Calibration Factor

Echo Flow Probe Swan Ganz Literature Reference

The type of catheter connected to the ADV500 will populate a default value (ex. 20uL for mouse); however, use one of the following options to determine the most accurate reference as possible…

2. Blood Resistivity (Rho)

Resistivity (or conductivity) is a property of the blood being measured. Default values are provided in the ADV500 that represent healthy non-modified mammalian blood at 37C. If your experiments involve changing blood properties (ie. hemorragic shock models), make measurements manually and address both pre and post blood change states.

Manual Sample

3. Heart Type (Muscle Electrical Property)

• The ADV 500 uses the term “Muscle Properties” to describe the ability of the myocardium to conduct a constant AC current signal.

• It is important to acknowledge this calibration parameter since it will impact how much tissue contribution is removed from the measured admittance signal. The ADV500 offers 3 default options for Heart Type:

Healthy , Infarcted or Hypertrophied

• A fourth option is to select “Custom” and use the supplied probe to obtain a value by placing it on the LV surface of a beating heart

Surgical Considerations & Best-Practices for Successful PV Data Collection

Filip Konecny, DVM PhD

Applications Scientist & Surgical Trainer

Transonic

Copyright 2015 InsideScientific & Transonic. All Rights Reserved.

Overview

1. Surgical Considerations – Rodent non-survival applications

• Anesthesia, Analgesia, Ventilation

• Monitoring Physiology (HR, BT, RR, and ECG)

2. Optimizing Pressure-Volume Signals

• Catheter Placement

• Performing a baseline scan

• Validating your “baseline data”

• 3 steps to good PV data

Anesthesia, Analgesia, Ventilation

DO… • weigh each subject to calculate proper anesthetic dose

• adhere to suggested delivery and administration guidelines for selected anesthetic request a copy of our Rodent PV Workbook

DO NOT… • use expired pharmaceutical grade injectable compounds

• use expired anesthetic/sedative antagonists

• use an expired vaporizer

• use a non-compatible VAPORIZER for your chosen anesthesia

Tip: learn about anesthetics and their effects on hemodynamics

Anesthesia, Analgesia, Ventilation

DO…

• administer analgesics to control pain

• optimize analgesia delivery with anesthesia – animals that receive pre-operative analgesia often require less anesthetic to reach a surgical plane

• work in pairs or teams if possible – animal physiology and vitals can be better monitored by one partner while the other focuses on surgery and PV measurements

• monitor anesthetic depth using the following techniques: Toe pinch, Palpebral reflex, Corneal reflex

• continually monitor vital signs and animal physiology to maintain a stable prep

Tip: Select Anesthesia that you can readily reverse that has predictable effect on heart

Monitoring Physiology (HR, BT, RR, and ECG)

DO… • have suitable equipment to control body

temperature

• have suitable equipment to monitor Heart Rate, Body Temperature, Respiration Rate, and ECG

• consider taking blood gas measurements or measuring *SpO2 –(noninvasive, fast, continuous)

• monitor continuously and save data throughout your experiment – consider integration with PV data into one acquisition file

Tip: vital signs monitoring is crucial for PV repeatability

Monitoring Physiology (HR, BT, RR, and ECG)

Mouse Rat

Temperature 35.8 - 37.4 °C 96.6 - 99.7 F

35.9 - 37.5 °C 96.6 - 99.5 F

Respiration Rate 90 – 220

breaths per min 66 – 144

breaths per min

HR 450 – 780 BPM 250 – 500 BPM

Additional Thoughts on Heating

Special Consideration – Maintaining Blood Volume

• loss of 10 % total blood volume is tolerable (for PV)

• loss of 20-25% will lead to shock (Final data not physiological)

• good PV vascular prep. technique will minimize blood loss

Species Blood Volume Blood loss (10%) Blood loss (20%)

Mouse 20g 1.5 ml 0.15 ml 0.3 ml

Rat 250g 15-18ml (17) 1.7ml 3.4ml

Special Consideration – Maintaining Blood Volume

• Rodents (particularly mice) have a high body surface-area to blood volume ratio, high metabolic rate, and limited fat storage RESULT: greater risk of dehydration

• Therefore, it is better to compensate and plan for blood loss by having a consistent and standard pre-operative injection plan (IP route is most common)

Species SC or IP fluids IV fluids PO fluids intake

Mouse 20g 0.15 ml 2ml/100g/hr 1.2ml/24h

Rat 250g 1.7ml 2ml/100g/hr 17ml/24h

Surgical Documentation & Study Approach

DO… • Document ALL Settings: equipment, surgical

methodology, and operation details download our PV Loop Surgery Documentation Sheet

• work through cohorts: if different animal groups in your study have different volume calibration factors (SV correction factor) or require PV catheters with different electrode spacing (rat dilated cardiomyopathy)

• utilize “marks” and “comment” functions in your data acquisition software –input details specific to the animal being studied (volume calibration factors), and make note of unique occurrences during the work

3 Steps To Good PV Data

• Turn on system and start catheter hydration

• Enter values for Admittance cal. factors: 1. Stroke volume 2. Blood resistivity 3. Heart type

• Balance pressure sensor

Step 1

• Place catheter into ventricle

• Position catheter in center of ventricle by viewing Pressure vs. Magnitude loops and phase signal

• Once optimal signals are achieved, press “Enter” during acquisition to perform a baseline scan

• Accept the reported scan numbers, or rescan if needed

Step 2

• Switch to Pressure vs. Volume loops view

• Continue with protocol steps (injections, occlusions, etc.)

• Use software analysis features to study hemodynamic results

Step 3

Transition Guided by Pressure Note the drop of the pressure at the end diastole when entering into LV chamber through RCA (right carotid artery)

Use the pressure signal to confirm that the catheter has entered the ventricle

Understanding “Magnitude” • Sinusoidal pattern

of the wave

• Concentrate on Magnitude Amplitude and Range at the same time

See table for specific ranges and values by animal model

Understanding “Phase”

• Sinusoidal pattern of the wave

• Concentrate on Phase amplitude and range at the same time

See table for specific ranges and values by animal model

Typical Values in Healthy Subjects

Animal Phase Range

Phase Amplitude

Magnitude Range

Magnitude Amplitude

Rat 2-6 2.0 1400-2600 µS 600-1000 µS

Rabbit 2-6 2.0 8-14 mS 2-3 mS

Small Dog 1-5 1.5 10-16 mS 2-3 mS

Large Dog (>15kg) 1-5 1.5 12-18 mS 2-4 mS

Small Swine 1-3 1.5 12-18 mS 2.5-4 mS

Large Swine (>65kg) 1-3 1.5 15-30 mS 4-6 mS

Sheep 1-3 1.5 14-22 mS 4-5 mS

Cow 2-5 2.0 20-40 mS 10-15 mS

Signs of a Good Baseline Scan • Once phase and

magnitude “look good”, perform a baseline scan

• Observe a short break in data recording (shown here)

• The result should be stable, accurate volume… if not, adjust catheter, repeat scan

• Pressure –Magnitude loop Looks good

• However, phase range is too high for mouse (~8-10 deg.)

• Catheter needs repositioning

Catheter Positioning

Catheter Positioning • Pressure-Volume: same data set from previous slide, but now we are viewing Pressure vs. Volume

• Note – Volume is not calculating correctly… this is because the catheter is not in the center of the ventricle

• Phase angle can be used as a guidance of the catheter position in the chamber

Catheter Positioning • Catheter position is

adjusted followed by baseline scans

• Volume is now accurate and the user can move forward with their protocol

3 Steps To Good PV Data

• Turn on system and start catheter hydration

• Enter values for Admittance cal. factors: 1. Stroke volume 2. Blood resistivity 3. Heart type

• Balance pressure sensor

Step 1

• Place catheter into ventricle

• Position catheter in center of ventricle by viewing Pressure vs. Magnitude loops and phase signal

• Once optimal signals are achieved, press “Enter” during acquisition to perform a baseline scan

• Accept the reported scan numbers, or rescan if needed

Step 2

• Switch to Pressure vs. Volume loops view

• Continue with protocol steps (injections, occlusions, etc.)

• Use software analysis features to study hemodynamic results

Step 3

Thank You! For additional information on Pressure-Volume Loop best-practices and solutions for studying hemodynamics please visit:

http://www.transonic.com

NEXT WEBINAR: Dr. James Clark of King’s College London will present surgical monitoring best-practices, and demonstrate how to improve study and animal outcomes in CV related research studies using integrated surgical monitoring combined with hemodynamic measurements.

WORKSHOP: