Arterial Waveform: Systole begins during the sharp rise from the baseline (troughs). Diastole begins on the down slope where the bulge appears. The bulge is referred to as the dicrotic notch. This signifies the closure of the aortic valve at the end of systole. The peaks average the systolic pressure. The troughs average the diastolic pressure. With an arterial waveform, note the scale range. Systolic and diastolic blood pressure ranges should fit within the scale of the waveform. If the scale is less than 60 mm Hg, then the waveform is probably not arterial but more likely a waveform from a pulmonary artery catheter.
CENTRAL VENOUS PRESSURE WAVEFORM
Central Venous Pressure (CVP) Waveform: The CVP waveform can be recognized by the triplet of peaks. The highest peak is the a-wave; and it represents right atrial contraction at the end of diastole. The following c-wave, which is generally smaller, represents closing of the tricuspid valve; this is the signification of beginning of systole. The c-wave is followed by an x-slope (or trough), which is caused by right atrial relaxation. The v-wave stands alone between two slopes, and it represents right atrial filling pressure during diastole. The following y-slope represents opening of the triscuspid valve. Recordings of CVP readings are made of the mean CVP pressure which = (systolic + 2(diastolic))/3. The monitoring system records the mean CVP as the parameter. Because there are no valves between the superior vena cava and the right atrium, the CVP waveform can be compared to jugular venous pulsations. Sometimes, the CVP is recorded through a central venous catheter (distal port if the catheter has triple-lumens) with a water column type of monitor.
RIGHT VENTRICULAR PRESSURE WAVEFORM
Right Ventricular (RV) Waveform: When a pulmonary artery catheter advances into the right ventricle, dramatic changes occur. Notice the drop in the baseline first. Diastole in a ventricle becomes very close to zero. Also, as diastole comes to an end, the pressure begins to rise revealing a little hill with what is referred to as the end-diastolic pressure–this is associated with ventricular filling of blood prior to ventricular contraction. Systole begins with a very sharp upstroke on top of the little hill. Again, the range is important to note because right ventricular systolic pressures are generally less than 40 mm Hg. Left ventricular systolic pressures will be much higher comparable to arterial systolic pressures ranging greater than 100 mm Hg. Pressure recordings include systole, diastole, and end-diastole.
PULMONARY ARTERY PRESSURE WAVEFORM
Pulmonary Artery (PA) Pressure Waveform: Notice the similarity between the pulmonary artery pressure waveform and the arterial pressure waveform. Systole begins during the sharp upstroke from the trough. Diastole begins at the dicrotic notch on the backside of the waveform. This is an arterial waveform, but it is for the pulmonary artery. Pay attention to the scale at the left. For a pulmonary artery, the scale will be no more than 40 mm Hg usually (60 mm Hg if PA pressures are extremely high > 40 mm Hg).
PULMONARY ARTERY OCCLUSIVE PRESSURE WAVEFORM:
Pulmonary Artery Occlusive Pressure (PAOP) Waveform: Note the 2 beats of pulmonary artery pressure waveform at the beginning of this pressure strip. If the pulmonary artery becomes occluded, then the only pressure reading at the distal end of a pulmonary artery catheter is retrograde–that means that the pressure is coming from a distal location, specifically the left atrium. There are no valves between the pulmonary veins and the left atrium, so the left atrial pressure is reflected back to the tip of the pulmonary artery catheter. Notice the triplet pressure waves (a, c, & v) and the double slopes (x & y) that are similar to CVP pressure waveform. The CVP waveform is a representation of the right atrial pressures, and the PAOP waveform is a representation of the left atrial pressures. Like the CVP, the readings for PAOP are recorded of the mean pressure in the left atrium. Pulmonary artery occlusive pressure (PAOP) is also commonly referred to pulmonary capillary wedge pressure (PCWP) or simply as a "wedge" pressure.