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