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 the tissues and
lungs.
36. Measuring pulmonary artery pressure Normal Value 15-25/8-15
mmHg. Systole measured at the peak of the wave Diastole measured
just prior to the upstroke of systole (end of QRS) Higher than RV
diastolic pressure
37. Differentiating the Right Ventricle and Pulmonary Artery
Waveforms The wave looks taller. The systolic pressure equals the
previously recorded pulmonary artery systolic pressure. The
diastolic pressure matches the right atrial diastolic pressure.
Inflation of the balloon fails to produce a PAWP waveform. The
waveform is symmetrical in shape. There is no dicrotic notch. A
small preliminary rise in late diastole is present prior to the
main rise in the pressure waveform. The new pressure is closer to
the QRS than the previous pulmonary artery tracing. RV waveform PA
Waveform
38. Pulmonary artery catheter waveforms RA RV PA PAWP