8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

1/14

PRINCIPLES OF INVASIVEHEMODYNAMIC

MONITORINGMarelno Zakanito

030.07.153

Pembimbing:dr. Dean Wahjudy ,Sp.OG

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

2/14

There are four basic parameters necessary to describe

comprehensively the hemodynamic status of any

pregnant patient:

preload,

afterload,

contractility,

and heart rate.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

3/14

Preload

Preload refers to the volume of blood contained within a

ventricle at cardiac end-diastole.

Preload is determined by blood return to the ventricle and

thus is directly related to intravascular volume.

If increased amounts of blood enter the heart during

diastole. The normal heart will respond with increased

velocity of contraction and thus increased stroke volume.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

4/14

Afterload

Afterload represents the downstream resistance offered to

each ventricle during cardiac systole. Cardiac output is

inversely related to afterload (figure 4-1).

Clinically, afterload is assessed as systemic vascular

resistance, a derived parameter based upon blood

pressure, central venous pressure, and cardiac output.

Right ventricular afterload is represented by pulmonary

vascular resistance, and left ventricular afterload by

systemic vascular resistance.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

5/14

Figure 4-1

Cardiac output (CO)

versus mean arterial

pressure (MAP).

Increasing systemicvascular resistance

(SVR) is demonstrated

by isometric lines.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

6/14

Figure 4-2 ventricular

end-diastolic volume

versus ventricular

performance. Increased.

Normal and impairedcontractility are

demonstrated.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

7/14

Contractility

Contractility refers to the intrinsic contractile property of

the myocardium. While alterations in preload affect the

movement of stroke volume along a given Starling curve,

alterations in contractility affect the Starling curve upon

which the cardiac output operates (figure 4-2)

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

8/14

Contractility may be altered by various disease states or

by pharmacologic agents that have positive or negative

inotropic effects. One of the most useful measures of

contractility is stroke work index, a derived parameter

(figure 4-3)

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

9/14

Heart Rate

Cardiac output is also directly affected by heart rate,

independent of either Starlings forces or alterations in

contractility. In the normal heart, cardiac output generally

increases with normal heart rate to the limits of

physiologic tachycardia.

However, at extremely rapid rates, ventricular filling and

end-diastolic volume will be diminished because of

inadequate diastolic filling time; under these

circumstances, cardiac output will decrease.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

10/14

Figure4-3

Pulmonary capillary

wedge pressure

(PCWP) versus left

ventricular stroke workindex (LVSWI): Normal

relationship represented

by shaded area.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

11/14

Clinical Assessment

In practice, blood pressure, pulse, and body surface area

are measured in standard clinical fashion. Central venous

and pulmonary capillary wedge pressure are measured

from the proximal and distal ports of pulmonary artery

catheter. Cardiac output is measured using thermodilution technique associated with the pulmonary artery

catheter and a cardiac output computer. Once these

parameters have been obtained clinically, derived

parameters such as systemic and pulmonary vascularresistance and left ventricular stroke work index may be

calculated in putting together the complete hemodynamic

picture of the patient.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

12/14

Blood Pressure

True interarterial pressures obtained by direct arterial line

measurements are more accurate than cuff pressures. As

a rule, interarterial catheters result in pressure from 4-8

mm higher than corresponding cuff pressures. This

principle, however, is generally valid only in normalpatients; in certain subsets of critically ill patients,

interarterial pressure may be up to 30 mmHg higher than

those obtained from a peripheral cuff.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

13/14

Mixed Venous Oxygen Saturation

(SV02) Monitoring SV02 may be assessed either periodically by direct

sampling from the distal port of pulmonary artery catheter

or continuous use of a pulmonary artery catheter

equipped with fiberoptic oximetry sensor. SVo2is

determined by four parameters: cardiac output.

8/11/2019 Principles of Invasive Hemodynamic Monitoring Xxx

14/14

Pulse Oximetry

Pulse oximetry is based upon the principle of differential lighttransmittance by oxygenated and nonoxygenated hemoglobinand depends upon the use of two light-emitting diode(LED)sources; one red (660 nanometers) and one infrared (940nanometers). Using a spectrophotometric device and an

associated microprocessor, pulse oximeters will evaluate 02saturation with each pulse. In critically ill pregnant patients withtenuous physiologic oxygenation, pulse oximetry is aninvaluable technique. The use of this technique often allows theclinician to avoid multiple arterial blood gases and, at the same

time, provides a continuous rather than intermittent method ofpatient evaluation. This technique should be a routine part ofthe management of any critically ill patient whose oxygenstatus is or may be compromised. Recent investigations intothe use of fetal pulse oximetry may also prove clinically fruitful.