Normal Range for Systemic Vascular Resistance (SVR)
The normal range for systemic vascular resistance is 800 to 1200 dyne·s⁻¹·cm⁻⁵, as established by consensus guidelines for hemodynamic management. 1
Standard Reference Values
SVR is calculated as (mean arterial pressure minus right atrial pressure) divided by cardiac output, expressed in dynes·s⁻¹·cm⁻⁵ 1, 2
The normal range of 800 to 1200 dyne·s⁻¹·cm⁻⁵ represents the target for optimal hemodynamic management in critically ill patients, including cardiac donors and those requiring intensive care 1
When indexed to body surface area (SVRi), the normal range is approximately 1800 to 2500 dyne·s·cm⁻⁵·m² 3
Clinical Significance of Abnormal Values
Low SVR (Below 800 dyne·s⁻¹·cm⁻⁵)
SVR below 800 dyne·s⁻¹·cm⁻⁵ is associated with significantly increased mortality in both septic and non-septic conditions 4, 5
Extremely low SVR (below 450 dyne·s⁻¹·cm⁻⁵) carries particularly high mortality risk regardless of underlying etiology 4
Low SVR states occur in approximately 44% of patients after cardiopulmonary bypass and 25% of hypotensive patients have non-septic causes of low SVR 4, 3
High SVR (Above 1200 dyne·s⁻¹·cm⁻⁵)
Clinical signs of elevated SVR include absent or weak distal pulses, cool extremities, prolonged capillary refill, and narrow pulse pressure with relatively increased diastolic blood pressure 1, 6, 2
High SVR with normal blood pressure but reduced ventricular function indicates reduced cardiac output 2
Marked elevation in SVR can reduce blood flow sufficiently to cause shock 2
Measurement Considerations
Pulmonary artery catheter provides the most accurate assessment of SVR through direct measurement 6, 2
The major determinant of SVR is arteriolar tone, though blood viscosity and vascular capacitance also contribute 1, 2
SVR measurement reliability can be affected by extreme values, with monitoring devices showing decreased accuracy at very high or very low SVR states 7
Critical Clinical Context
In pediatric septic shock, maintaining cardiac index between 3.3 and 6.0 L/min/m² with SVR in the normal range is associated with best outcomes 1, 6, 2
In cardiovascular intensive care, SVR must be maintained greater than pulmonary vascular resistance to ensure adequate right ventricular coronary perfusion 6, 2
Target SVR of 800 to 1200 dyne·s⁻¹·cm⁻⁵ is specifically recommended during hormonal resuscitation protocols with vasopressin titration 1