Hemodynamics Hemodynamics
The study of forces involved in the flow of blood through the cardiovascular and circulatory systems
Components:
Blood pressure
Central venous pressure
Right and left heart pressures
Assessment of ventricular function through evaluation of hemodynamic variables enables the nurse to identify cardiovascular problems and to determine appropriate interventions
Hemodynamic Monitoring Non-invasive
E.g. blood pressure monitoring or mean arterial pressure
Invasive
Used to make actual measurements of pressures (i.e. directly within the heart)
Allows the nurse to have access to much more information about the status of the patient But this will never replace hands-on patient assessment
Primary purpose: Early detection, identification and treatment of life-threatening
conditions such as heart failure and cardiac tamponade
Allow immediate evaluation of patient’s response to treatment such as drugs and mechanical support
Indications for Hemodynamic
Monitoring Signs of severe dehydration, hemorrhage, G.I. bleed
Burns or surgery
All types of shock
Any deficit or loss of cardiac function (such as AMI or
CHF)
Hemodynamic parameters Cardiac Output (CO)
The volume of blood ejected from the heart per minute
A function of heart rate and stroke volume (CO = HR x SV)
Must generate enough pressure in systole to overcome aortic pressure and systemic vascular resistance and eject sufficient blood volume to perfuse the organs of the body
Normal value: 4 to 8L/min at rest
Cardiac Index (CI)
an adjustment of the cardiac output
considers the patient’s body size (or Body Surface area)
Formula: CI = CO / BSA
Normal value: 2.5 t0 4 L/min/m2
Heart Rate (HR)
Often overlooked, but very useful and simple
Detects cardiac dysrrhythmias, such as bradycardia or tachycardia
Normal value (in adult): 60 to 100 beats per minute Heart rate that is more than 120 bpm decreases cardiac output
due to decreased ventricular filling time
Stroke Volume (SV)
Volume of blood ejected with each ventricular contraction
In cardiac dysfunction, the SV decline is not immediately apparent
Formula: SV = CO / HR
Hemodynamic parameters
Central Venous Pressure (CVP)
A measurement of the right atrium
Reflects the right ventricular diastolic pressure, or the ability of the right side of the heart to pump blood
Used for assessing the relationship between cardiac action, vascularity and blood volume
Used for prescribing fluid replacement or restrictions more accurately
Normal value: 2 to 6 mmHg Decreased CVP may indicate hypovolemia, neurogenic shock
or anaphylactic shock
Increased CVP may indicate right ventricular dysfunction, cardiac tamponade, constrictive pericarditis, pulmonary hypertension, tricuspid stenosis or tricuspid regurgitation
Hemodynamic parameters
Components of
Hemodynamic Monitoring Amplifier – located inside the bedside monitor;
increases the size of signal from the transducer
Recorder or monitor – to display the signal and record
information
Transducer – changes the mechanical energy or the
pressures of pulse into electrical energy
Supplemental equipment
Pressure tubing – prevents tubing distention
Video (CVP)
Nursing considerations
Always level and zero the system to ensure accuracy of values
obtained
Leveling
Performed to eliminate the effects of hydrostatic pressure on
the transducer
Should be done before and after connecting the pressure
system to the patient, with every change in position of the
patient and prior to zeroing and calibration
Nursing considerations
Always level and zero the system to ensure accuracy of values
obtained
Zeroing
Performed to eliminate the effects of atmospheric pressure
on the transducer
Should be performed before and after connecting the
pressure system to the patient, with any leveling and
whenever there is a significant change in the hemodynamic
variables
All values should be rated at the end of expiration
The catheter must be flushed at least every 8 hours
Precaution
Follow electrical safety monitoring guidelines
Risk to patient: ventricular fibrillation
A defibrillator, emergency crash cart and medications
must be readily available
Nursing considerations
Complications Pneumothorax
During catheter insertion, the needle may puncture
the apical lung as it passes through the subclavian
vein
Constant wedging of the PA catheter
The catheter may migrate into smaller pulmonary
vessel resulting in pulmonary ischemia
This is an emergency!
If this occurs, the catheter balloon must be deflated,
and the catheter must be pulled back slightly
Ventricular irritation
Occurs when the catheter floats back into the right
ventricle or is looped through the ventricle
May cause ventricular dysrhythmmias
Notify the physician if the catheter needs to be
floated back into the pulmonary artery
Complications
Air embolism
May occur when the balloon ruptures
Causes pulmonary embolism
When inflating the balloon, feel for resistance and
watch for a dampened waveform. No resistance and
no wedge are indications of a ruptured balloon
If this happens, remove the syringe, close the port
and label the port that the balloon is ruptured
Complications
Dampened waveform
May be caused by kinks, bubbles within the lines,
clots or the catheter may be against the vessel wall
Complications
Dampened waveform
May be caused by kinks, bubbles within the lines,
clots or the catheter may be against the vessel wall
Infection
Always observe sterile technique
Complications
Infection
Always observe sterile technique
Complications
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