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INTRODUCTION

KNOWLEDGE COMPETENCIES

  1. Identify the characteristics of normal and abnormal waveform pressures for the following hemodynamic monitoring parameters:

    • Central venous pressure

    • Pulmonary artery pressure

    • Arterial blood pressure

  2. Describe the basic elements of hemodynamic pressure-monitoring equipment and methods used to ensure accurate pressure measurements.

  3. Discuss the indications, contraindications, and general management principles for the following common hemodynamic monitoring parameters:

    • Central venous pressure

    • Pulmonary artery pressure

    • Mixed venous oxygenation

    • Arterial blood pressure

    • Cardiac output

  4. Describe the use of SvO2/ScvO2 monitoring in the critically ill patient.

  5. Describe the use of functional hemodynamic measures, including analysis of pulse pressure and stroke volume variation during positive pressure ventilation, and the passive leg raising maneuver.

  6. Describe the use of peripheral perfusion indicators, including of capillary refill time and skin mottling in critically ill patients.

  7. Compare and contrast the clinical implications and management approaches to abnormal hemodynamic values.

OVERVIEW

The term hemodynamics refers to the interrelationship of blood pressure (BP), blood flow, vascular volumes, heart rate (HR), ventricular function, and the physical properties of the blood. Monitoring the hemodynamic status of the critically ill patient is an integral part of critical care nursing. It is essential that critical care nurses have a working knowledge of how to obtain accurate data, analyze waveforms, and interpret and integrate the data.

Clinical examination findings such as mental status, urine output, edema, jugular venous distention, capillary refill time, skin mottling, skin temperature, and skin color provide some data about a patient’s fluid balance, oxygenation, and perfusion. Additional data can be obtained through noninvasive and invasive hemodynamic monitoring and functional hemodynamic assessment. Parameters such as arterial BP, cardiac output (CO), pulmonary arterial pressure (PAP), and intracardiac pressures can be directly measured and monitored with special indwelling catheters. Less invasive evaluations include the passive leg raise (PLR) maneuver and cardiovascular ultrasound. Analysis of changes in the arterial waveforms in patients on positive pressure mechanical ventilation can also provide information about the patient’s fluid responsiveness that guides management. Understanding how to gather hemodynamic data and interpret it is an essential function of the critical care nurse.

Adapted from Leanna R. Miller

ANATOMY AND PHYSIOLOGY

Cardiac Output

CO is the amount of blood pumped by the ventricles each minute. It is the product of the HR and the stroke volume (SV) which is the amount of blood ejected by the ventricle with each contraction. See Figure 4-1.

Figure 4-1.

Factors affecting CO.

CO = HR × SV

The normal value of cardiac output is 4.0 to 8.0 L/min (Table 4-1). It is important to note that CO values are relative to size. Values within the normal range for a person 5-ft tall ...

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