Pressure, Flow, and Resistance

1
Pressure, Flow, and Resistance

• Understanding the relationship among pressure,
  flow and resistance can help you understand how
  cardiac output and vascular resistance relate to
  blood pressure
• These are relationships that are often
  manipulated in the acutely ill patient
• The relationship among flow, resistance and
  pressure can be mathematically expressed Flow x
  Resistance Pressure

2
Pressure, Flow, and Resistance

• Flow and resistance can be adjusted to keep
  pressure steady
• The flow in the cardiovascular system is the CO,
  the resistance is the afterload and the pressure
  is the blood pressure

3
Normal Pressures

• When a catheter is passed through the venous
  system into the heart and pulmonary artery,
  certain pressure readings and wave forms are
  measurable
• During each individual section to follow, we will
  be looking at normal waveforms displayed
  depending on type of hemodynamic monitoring being
  used eg. arterial waveforms, CVP waveforms and PA
  waveforms
• To end this section I will leave you with the
  normal values. We will revisit them again during
  the sections to follow

4
Hemodynamic Pressures

• Central Venous Pressure (CVP)
• 0 6 mm Hg
• Right Arterial Pressures (RAP)
• 0 6 mm Hg
• Right Ventricular Pressures (RVP)
• Systolic 20 30 mm Hg
• Diastolic 2 8 mm Hg
• RV End Diastolic 2 6 mm Hg
• Pulmonary Artery Pressures (PAP)
• Systolic 20 30 mm Hg
• End diastolic 8 15 mm Hg
• Pulmonary Artery Wedge Pressures
• (PAWP) (PAOP) (PCWP) 5 12 mm Hg

5
Hemodynamic Monitoring

• The high acuity patient has complex nursing needs
• The nurse requires a working knowledge of the
  determinants of cardiac output, preload,
  afterload, and contractility
• These determinants of cardiac output will be
  linked to the data available through hemodynamic
  monitoring with a pulmonary artery line
• This knowledge, coupled with astute observation
  and sharp assessment skills, can guide critical
  thinking at the bedside and provide a higher
  level of nursing care for the high acuity patient