Hemodynamic Terminology

There are a number of hemodynamic terms that you will need to understand in order to properly interpret the hemodynamic measurements. The following table presents common values of hemodynamic parameters.

• Please be aware that these normal values may vary depending on your instrumentation, so always rely on your institution's policies and procedures.
• Some of the values are actual measurements of pressure (mm Hg), volume (ml), or flow speed (L/min), and other values are calculated or "derived" from formulae.
  

• Afterload: Afterload describes the resistance that the heart has to overcome, during every beat, to send blood into the aorta. These resistive forces include vasoactivity and blood viscosity.
• Cardiac Index (CI): The amount of blood pumped by the heart, per minute, per meter square of body surface area (BSA = The square root of [bodyweight (kg) x height (cm) / (3600)]).
• Cardiac Output (CO): The volume of blood pumped by the heart in one minute.
  • Increased cardiac output may indicate a high circulating volume.
  • Decreased cardiac output indicates a decrease in circulating volume or a decrease in the strength of ventricular contraction.
• Central Venous Pressure (CVP): CVP readings are used to approximate the Right Ventricular End Diastolic Pressure (RVEDP). The RVEDP assesses right ventricular function and general fluid status.
  • Low CVP values typically reflect hypovolemia or decreased venous return.
  • High CVP values reflect overhydration, increased venous return or right sided cardiac failure.
• Mean Arterial Pressure (MAP): Reflects changes in the relationship between cardiac output (CO) and systemic vascular resistance (SVR) and reflects the arterial pressure in the vessels perfusing the organs.
  
  • A low MAP indicates decreased blood flow through the organs.
• A high MAP indicates an increased cardiac workload.
• Preload: is an estimate of end-diastolic pressure in the left ventricle (LVEDP). It reflects the volume of blood returned to the LV just before systole.
  • Volume reduction decreases preload
  • Volume increase will increase preload, mean arterial pressure (MAP) and stroke index (SI).
• Pulmonary Artery Pressure (PA Pressure): Blood pressure in the pulmonary artery.
  • Increased pulmonary artery pressure may indicate: a left-to-right cardiac shunt, pulmonary artery hypertension, COPD or emphysema, pulmonary embolus, pulmonary edema, left ventricular failure.
• Pulmonary Capillary Wedge Pressure (PCWP or PAWP): PCWP pressures are used to approximate LVEDP (left ventricular end diastolic pressure).
  • High PCWP may indicate left ventricle failure, mitral valve pathology, cardiac insufficiency, cardiac compression post hemorrhage.
• Pulmonary Vascular Resistance (PVR): The measurement of resistance or the impediment of the pulmonary vascular bed to blood flow.
  
• An increased PVR or "Pulmonary Hypertension" is caused by pulmonary vascular disease, pulmonary embolism, or pulmonary vasculitis, or hypoxia.
• A decreased PVR is caused by medications such as calcium channel blockers, aminophylline, or isoproterenol or by the delivery of O2.
• Right Ventricular Pressure (RV Pressure): A direct measurement that indicates right ventricular function and general fluid status.
  • High RV pressure may indicate: pulmonary hypertension, right ventricle failure, congestive heart failure.
• Stroke Volume (SV): The amount of blood pumped by the heart per cardiac cycle. It is measured in ml/beat.
  • A decreased SV may indicate impaired cardiac contractility or valve dysfunction and may result in heart failure.
  • An increased SV may be caused by an increase in circulating volume or an increase in inotropy.
• Systemic Vascular Resistance (SVR): The measurement of resistance or impediment of the systemic vascular bed to blood flow.
  • An increased SVR can be caused by vasoconstrictors, hypovolemia, or late septic shock.
  • A decreased SVR can be caused by early septic shock, vasodilators, morphine, nitrates, or hypercarbia.

References

DeMers D, Wachs D. Physiology, Mean Arterial Pressure. [Updated 2021 Apr 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538226/

Edwards Lifesciences (2017). Normal Hemodynamic Parameters and Laboratory Values. Accessed 12/15/2021 from https://edwardsprod.blob.core.windows.net/media/Br/devices/monitoring/hemodynamic%20monitoring/normal_
hemodynamic_parameters_pocket_card.pdf

Jain V, Bordes S, Bhardwaj A. Physiology, Pulmonary Circulatory System. [Updated 2021 May 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK525948/

Nair R, Lamaa N. Pulmonary Capillary Wedge Pressure. [Updated 2021 Apr 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557748/

Patel N, Durland J, Makaryus AN. Physiology, Cardiac Index. [Updated 2021 Sep 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539905/

Procter, L. D. (2020). Intravenous fluid resuscitation - critical care medicine. Merck Manuals Professional Edition. Retrieved December 14, 2021, from https://www.merckmanuals.com/professional/critical-care-medicine/shock-and-fluid-resuscitation/intravenous-fluid-resuscitation.

Shah P, Louis MA. Physiology, Central Venous Pressure. [Updated 2021 Sep 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519493/

Whelton PK, Carey RM, Aronow, WS, Casey DE, Collins KJ, Himmelfarb CD, et al. (2017) ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2018;71(19):e127–e248.