haemodynamic wave forms
Post on 07-Aug-2015
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- 1. By Dr. Samiaa Hamdy Sadek Lecturer of chest diseases Assiut University
- 2. Definition: Hemodynamic waveforms are maps of the pressure changes that take place within a given vessel or chamber. All of the waveforms obtained from arterial lines, pulmonary artery catheters, or during cardiac catheterization can be recognized by recalling 3 basic waveform morphologies.
- 3. These waveform shapes include: 1) Atrial 2) Arterial, and 3) Ventricular waveforms. Because both atria fill, empty and contract in the same sequence during systole and diastole, the right atrial and left atrial waveforms have similar patterns. Similar changes occur between the pulmonary artery and aorta, and the right and left ventricles.
- 4. pulmonary artery catheter (Swan Ganz) Standard PAC is 7.0, 7.5 or 8.0 French in circumference and 110 cm in length divided in 10 cm intervals. The catheter tip if properly inserted, rests in a pulmonary arteriole. Patency of the Distal lumen is achieved by maintaining a continuous flow of heparinized saline at a rate of 3cc/hour. Developed by Swan Ganz and colleagues in 1970
- 5. pulmonary artery catheter (Swan Ganz) PAC has 4-5 lumens: Temperature thermistor located proximal to balloon(blue arrow) to measure pulmonary artery blood temperature (yellow line) Proximal port located 30 cm from tip for CVP monitoring, fluid and drug administration (blue line) Distal port at catheter tip for PAP monitoring (black arrow) +/- Variable infusion port (VIP) for fluid and drug administration Balloon at catheter tip
- 6. Catheter component
- 7. Pulmonary artery pressure monitoring system
- 8. Indications: Diagnosis of shock Assessment of fluid volume status Measurement of cardiac output Monitoring and management of haemodynamically unstable patients Assess diagnosis of primary pulmonary hypertension, valvular disease, intracardiac shunts, cardiac tamponade, and pulmonary embolus
- 9. Positioning of PAC It may be easy to remember the rule of 10s
- 10. Measuring central venous pressure 1- Water manometers 2-Electronic pressure transducer In contrast to electronic transducer water manometers overestimate CVP by 0.5-5cm H2O
- 11. CVP Recording The phlebostatic axis is the point where the fourth intercostal space and mid-axillary line cross each other regardless of head elevation.
- 12. Measuring CVP using a manometer 1. Line up the manometer arm with the phlebostatic axis . 2. Move the manometer scale up and down to allow the alignement with zero on the scale. This is referred to as 'zeroing the manometer
- 13. 3. Turn the three-way tap off to the patient and open to the manometer. 4. Move the manometer scale up and down to allow the bubble to be aligned with zero on the scale. This is referred to as 'zeroing the manometer'.Open the IV fluid bag and slowly fill the manometer to a level higher than the expected CVP Measuring CVP using a manometer
- 14. 5. Turn off the flow from the fluid bag and open the three-way tap from the manometer to the patient 6. The fluid level inside the manometer should fall until gravity equals the pressure in the central veins Measuring CVP using a manometer
- 15. 7. When the fluid stops falling the CVP measurement can be read. If the fluid moves with the patient's breathing, read the measurement from the lower number 8. Turn the tap off to the manometer Measuring CVP using a manometer
- 16. Measuring CVP using electronic transeducer The electronic transducer is a device that converts mechanical energy into an electrical waveform that is then displayed on the monitor as a waveform. These waveforms represent changes in pressure and are the result of physiological events, such as contraction of the heart. In order for the transducer to the supply the monitor with information that is clinically relevant to the monitor the transducer must be zeroed correctly and leveled at a known reference point.
- 17. 1. The CVC will be attached to intravenous fluid within a pressure bag. Ensure that the pressure bag is inflated up to 300mmHg. 2. Place the patient flat in a supine position if possible. Alternatively, measurements can be taken with the patient in a semi-recumbent position. Measuring CVP using electronic transeducer
- 18. 3. Tape the transducer to the phlebostatic axis or as near to the right atrium as possible. 4. Turn the tap off to the patient and open to the air by removing the cap from the three-way port opening the system to the atmosphere. Measuring CVP using electronic transeducer
- 19. Measuring CVP using electronic transeducer
- 20. 5. Press the zero button on the monitor and wait while calibration occurs. Measuring CVP using electronic transeducer
- 21. 6. When 'zeroed' is displayed on the monitor, replace the cap on the three-way tap and turn the tap on to the patient. Measuring CVP using electronic transeducer
- 22. 7. Observe the CVP trace on the monitor. The waveform undulates as the right atrium contracts and relaxes, emptying and filling with blood. (light blue in this image) Measuring CVP using electronic transeducer
- 23. Waveform recognition: 1. Atrial pressure waveforms (right atrial, PAWP): Waveforms obtained from the right and left atria have similar morphologies. Thus, CVP (right atrial) and left atrial pressure tracings have similar shapes. Pulmonary artery wedge pressure waveforms (PAWP) are indirect measurements of the left atrial pressure. Thus, CVP and PAWP waveforms have similar shapes. The right-sided pressures are slightly lower than the left.
- 24. Atrial pressure waveforms CVP shows three positive waves (a, c, v), and two descents (x, y). a wave represent increase in atrial pressure as a result of atrial contraction and pumping of blood in right ventricle. Begins in the PR interval and QRS on the ECG
- 25. Atrial pressure waveforms c wave result from increase of right atrial pressure as a result of closure of tricuspid valve. Observed in ST segment, may or may not present. v wave is the rise in atrial pressure as it refills during ventricular contraction. V wave correlates with T wave in ECG.
- 26. Atrial pressure waveforms Following contraction, the atria begin to relax, and the atrial pressures once again fall. This fall in atrial pressures is identified by the down slope of the a waves. This is referred to as the X descent. Opening of tricuspid and mitral valves during early diastole produce rapid decline in atrial pressure represented by Y descent.
- 27. Correlation to ECG First locate the v wave. It will appear immediately after the T wave on a CVP waveform, however, it will be .08-.12 seconds after the T wave on a PAWP tracing. If the patient has a sinus rhythm, an a wave should be in the PR interval for a CVP. It is later in the PAWP. If present, the c wave is generally within the QRS for a CVP. It will be after the QRS for a PAWP .
- 28. Measuring CVP and PAWP Normal CVP 0-8 mmHg, normal PAWP 8-12mmHg. Measure atrial pressure at end diastole which identified by mean of the highest and lowest a wave. Another way is Z-line(line from end of QRS to atrial tracing) it is delayed 0.08- 0.12 sec from QRS for PAWP. Z line
- 29. Normal Value 8-12 mmHg. The average of the highest and lowest value of a wave. Using z line which delayed 0.08-0.12sec after QRS. Measuring PAWP
- 30. PEEP and PAWP PAWP is not affected by PEEP pressures less than 10cm H2O. With PEEP pressures greater than 10, the pulmonary vasculature is compressed and the alveolar and intrathoracic pressure increased, thereby affecting the accuracy of the PAWP measurement. Calculation of PAWP with high levels of PEEP: 1. Convert the applied PEEP from centimeters of water to millimeters of mercury (1.36 cm H2O = 1 mm Hg) 2. Subtract half the applied PEEP in millimeters of mercury from the measured PAWP
- 31. 2-Ventricular pressure wave forms: During early diastole, the ventricles relax and stretch so the pressure in the ventricles remain very low. In late diastole, atrial contraction forces a bolus of blood into the ventricles, which can causes a small rise in the ventricular pressure. At the end of diastole ventricles begin to depolarize and ventricular pressure exceed atrial pressure, AV valves close while pulmonary and oartic valves also closed(isovolumetric contraction) with sharp rise in ventricular pressure.
- 32. 2-Ventricular pressure wave forms: As soon as the ventricles contract, blood leaves the ventricles, causing the ventricular pressures to begin to fall At end systole, the ventricles begin to stretch and relax, and the ventricular pressures fall to the their lowest point. Detection of right ventricular pressure rise using PAC is delayed after QRS in comparison to direct detection which occur with QRS complex.
- 33. Measuring RV pressure Normal Value 15-25/0-8 mmHg. Systole measured at the peak which occurs after the QRS Diastole measured just prior to the the onset of systole
- 34. Arterial waveforms As the ventricles contract, they eject blood into the pulmonary artery and aorta. This causes an immediate rise in the arterial pressure. Late in systole, the rate of ejection slows as the pressure gradient between the ventricles and arteries narrow, so the pressure begins to decline. This causes the early downslope in the arterial tracing
- 35. Arterial waveforms The ventricles begin to relax, causing the ventricular pressures to drop below the pressures in the great vessels. This causes the pulmonic and aortic valves to close, producing a dicrotic notch. Following closure of the semi-lunar valves, the pulmonary artery and aortic pressures continue to fall as blood leaves the great vessels to perfuse