# How are hemodynamic parameters calculated during pulmonary artery catheterization (PAC)?

Updated: Dec 22, 2017
• Author: Bojan Paunovic, MD; Chief Editor: Karlheinz Peter, MD, PhD  more...
• Print

Table 2 below shows the normal range of pressures for the RA, RV, PA, and PCWP.

Other important information provided by a PAC catheter includes the CO, mixed venous oxygen saturation (SaO2), and oxygen saturations in the right heart chambers to assess for the presence of an intracardiac shunt.

Using these measurements, other variables can be derived, including pulmonary or systemic vascular resistance and the difference between arterial and venous oxygen content (see the image and Table 1 below). Obtaining CO and PCWP measurements is the primary reason for inserting most PACs; therefore, understanding how they are obtained and what factors alter their values is of prime importance.

Normal hemodynamic parameters.

Table 1. Calculation of Various Hemodynamic Parameters (Open Table in a new window)

 Parameter Equation Systemic vascular resistance (SVR) SVR = (MAP – RAP/CO) × 80 Pulmonary vascular resistance (PVR) PVR = (PAP – PAOP/CO) × 80 Cardiac output (CO) CO = VO2 /(CaO2 – CvO2) Oxygen delivery (DO2) DO2 = CO × CaO2 × 10 Oxygen consumption (VO2) VO2 = (CaO2 – CvO2) × CO × 10 Arterial oxygen content (CaO2) CaO2 = (1.39 × Hb × SaO2) + (0.003 × PaO2) Venous oxygen content (CvO2) CvO2 = (1.39 × Hb × SvO2) + (0.003 × PaO2) Oxygen extraction ratio (O2ER) O2ER = VO2 /DO2 × 100 Intrapulmonary shunt (Qs/Qt) Qs/Qt = (PA-aO2) / (Ca­­-vO2) – shunt fraction Ca­­-vO2 = arteriovenous oxygen content difference; Hb = hemoglobin; MAP = mean arterial pressure; PA-aO2 = alveolar-arterial oxygen tension gradient; PAOP = pulmonary artery occlusion pressure; PaO2 = partial pressure of arterial oxygen; PAP = pulmonary artery pressure; Qs = ratio of shunted blood; Qt = total cardiac output; RAP = right atrial pressure (central venous pressure); SaO2 = arterial oxygen saturation; SvO2 = mixed venous oxygen saturation.

Table 2. Circulatory Pressures (Open Table in a new window)

 Circulatory Pressures, mm Hg Systolic Diastolic Mean AO 120 80 100 LV 120 8 - LA* 7 10 4 PA 15 7 12 RV 15 2 - RA* 4 4 0 PCW* 7 10 4 * A wave V wave