Haemodynamic Pocket Guide

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Hemodynamic Monitoring

(sec) 1.4

35 40 45 50 55 60

Technique

How often should it be done?

SvO2 Indicates adequacy of tissue oxygenation, the primary reason many patients receive hemodynamic monitoring

60-70%

The SvO2 helps identify which blood pressue and cardiac output are acceptable for each patient.

Level the transducer to the phlebostatic axis

Place any stopcock at the phlebostatic axis. Patient should be supine. Elevation can be from flat to 45 degrees

Only if the patient has moved from the original position. Relevel if reading has unexplainably changed.

Stroke Index (SI) How much blood is pumped with each beat referenced against body size.

25-45 ml/m2

Used in conjunction with cardiac pressures to diagnose and evaluate treatment.

Zero the Transducer/amplifier

Must zero on initial setup. Rezero if readings have unexplainably changed.

Cardiac Index How much blood is pumped during one minute reference against body size. It is a product of stroke index and heart rate

2.5-4.0 L/m/m2

Not as early an indicator of a hemodynamic problem as stroke index due to the compensating role of heart rate when stroke index is low.

With the stopcock off to the patient and open to air, cap removed and leveled at the phlebostatic axis, activate the monitor’s zero function. Close transducer to air and open to patient and then recap stopcock.

Perform a square wave test. The square wave test checks the accuracy of the tubing/ catheter system.

Activate the fast flush device and release. Interpret the response. See illustration below

Prior to obtaining readings

Pulmonary artery pressure (PAP)

About 25/10 mmHg

5 6

70

4 7

100 90 80

3

Hemodynamic Monitoring

2 8

Heart rate at 25 mm/sec (Measure two cardiac cycles from the reference arrow)

1 9

400 300

200 150

Steps

Pulmonary artery occlusive pressure (PAOP or wedge)

About 8-12 mmHg

When the stroke index is low, the PAOP helps differentiate left ventricular dysfunction (PAOP>12mmHg) and hypovolemia (PAOP< 8mmHg).

Central venous pressure (CVP) Right atrial pressure. A reflection of right ventricular end diastolic pressure. The CVP is an estimation of preload.

About 2-6 mmHg

When stroke index is low, the CVP helps differentiate right ventricular dysfunction (CVP> 6 mmHg) and hypovolemia (CVP is normal or < 2 mmHg.

Blood Pressure Reflects pressure in systemic arterial system.

Varies with site, size, age and sex.

A common less invasive form of estimating blood flow. With hemodynamic monitoring available (SvO2, SI, CI), blood pressure is less useful.

Systemic Vascular Resistance (SVR)

900-1300 dynes/sec/ cm5

Often used to assess the response of arterial dilators.

10

A supplement to CRITICAL CARE NURSE®

Printed in the USA, July 1999

Useful in assessing response to therapies for pulmonary hypertension. Normally not a primary parameter in assessing hemodynamics.

It is better way of verifying the arterial line accuracy than the blood pressure cuff comparison.

Performing Square Wave Test Characteristics

Illustration

How to correct? Clinical Result

Optimal Dampening 1) Should have a small overshoot, followed by a small overshoot (about 1/3 the distance of the undershoot) 2) Should have 1-2 blocks between oscillations

No necessary correction

Under Dampening 1) Either extra oscillations are present or 2) Prolonged distance (more than 2 blocks between bounces.

1)

Over Dampening 1) Obstruction in line prevents oscillation 2) Note slurring on downstroke.

Find source of problem. 1) Air in line 2) Blood in line 3) Kink in tubing/catheter

2)

Waveforms are accurately reproduced

Remove excess tubing. Insert dampening device Systole is artificially depressed, diastole may be higher than actual. Use mean values if unable to correct.

Page 1

Importance

8:03 AM

Normal Value

11/1/00

MM

REF 5968-6249E

Determining the Accuracy of Hemodynamic Values

Parameter

PR, QRS, and QT interval

30

REF

0.5

0.3

hemo_mont.qxd

0.1

Waveform

Pre C wave

Find the c wave on the downstroke of the a wave (usually near the end of the QRS complex)

Theoretically the most sound method. Use this method if possible

Right Ventricular 1) Rapid upstroke to waveform systole. Systole found after the QRS but before the T-wave. 2) Terminal diastolic rise-diastole found near the end of the QRS complex Pulmonary 1) Rapid upstroke to Artery waveform systole. Systole found after the QRS but before the T-wave. 2) Progressive diastolic runoff-diastole found near the end of the QRS complex. 3) A dicrotic notch (closure of the pulmonic valve) is sometimes visible during the progressive diastolic runoff.

Types of Artifact

How to Read

Patient initiated includes spontaneous breathing and patient initiated ventilator breaths

1) Locate where the baseline drops 2) Read the last clear wave before the drop occurs

Mechanical Ventilation

1) Locate where the baseline moved upward 2) Read the last clear wave before the baseline elevates.

Example

Page 2

Often the easiest to use since the c waves are not always visible. Use this method if c wave is not present.

Example

8:03 AM

Find the a wave in the PR interval. Locate top and bottom of a-c wave. Average the two values.

Characteristics

11/1/00

Indications

Average of the a-c waves

Avoiding Respiratory Artifact

How to read a Right Ventricular & PA waveform

Technique

How to read a PAOP waveform Avoiding Abnormal Waveforms

Z point

Draw a line down from the end of the QRS complex. Where the line hits the baseline, is the CVP reading.

Method

Technique

Indications

Average of the a-c waves

Find the a wave after the QRS complex. Locate top and bottom of a-c wave. Average the two values.

Often the easiest to use since the c waves are not always visible. Use this method if c wave is not present

Z point

Draw a line down from about .08 to .12 seconds after the QRS complex. Where the line hits the baseline, is the PAOP reading.

Use this method when no clear a or c wave present (e.g. atrial fibrillation and paced rhythms)

Use this method when no clear a or c wave present. (e.g. atrial fibrillation and paced rhythms)

Clinical Situation

How to Read

Large V wave Common with CHF

Locate the pre c point or the mean of the a-c wave before the large V wave.

Large or absent a Use the Z point method. wave

hemo_mont.qxd

How to read a CVP waveform Method

Example

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