What is QP to Qs ratio?

What is QP to Qs ratio?

The ratio of total pulmonary blood flow to total systemic blood flow, the Qp/Qs ratio, is a useful tool for quantifying the net shunt. A Qp/Qs ratio of 1:1 is normal and usually indicates that there is no shunting.

What does QP QS stand for?

Qp = Pulmonary flow. Qs = Systemic flow. Qp:Qs describes the magnitude of a cardiovascular shunt.

How do you calculate pulmonary flow?

Pulmonary blood flow can be determined by measuring the rate of gas intake into or extraction from the blood in the lungs and the changes in gas concentration in the bloodstream through the lungs. This technique is called the Fick method and is the standard method of cardiac output measurement (Guyton, 1963).

What causes increased PVR?

Factors that increase PVR include1: Hypoxemia. Acidemia. Hypercapnia (high partial pressure of arterial carbon dioxide [PaCO2]) Atelectasis.

What is Flamm’s equation?

(CaO2 = content of oxygen in arterial blood, CmvO2 = content of oxygen in venous blood (by Flamm’s formula (3SVC + IVC)/4), CpvO2 = content of oxygen in pulmonary venous blood, and CpaO2 = content of oxygen in pulmonary arterial blood.

What is normal shunt?

Anatomic shunt exists in normal lungs because of the bronchial and thebesian circulations, which account for 2-3% of shunt. A normal right-to-left shunt may occur from atrial septal defect, ventricular septal defect, patent ductus arteriosus, or arteriovenous malformation in the lung.

What is a normal SVR value?

Normal SVR is between 900 and 1440 dynes/sec/cm−5.

Is SVR and afterload the same thing?

Afterload, also known as the systemic vascular resistance (SVR), is the amount of resistance the heart must overcome to open the aortic valve and push the blood volume out into the systemic circulation.

How is the Qp and Qs ratio calculated?

Qp:Qs ratio is used to determine the ratio of the pulmonary to systemic blood flow across an intracardiac shunt, such as a PFO or a VSD. The Qp:Qs ratio can be calculated by using Doppler echo measurements of stroke volume at two locations and cross sectional area measurements from 2D echo.

What does the p stand for in Qp Qs?

The “p” stands for pulmonary and the “s” stands for systemic. So when we use the term Qp:Qs, what we’re saying it is the ratio of pulmonary blood flow to systemic blood flow. Qp:Qs ratio is used to determine the ratio of the pulmonary to systemic blood flow across an intracardiac shunt, such as a PFO or a VSD.

How to calculate the Qp of a shunt?

Qp/Qs can be estimated by using 2-D echo and spectral Doppler measurements in patients who have intra- or extra-cardiac shunts e.g. atrial or ventricular septal defects. Qp = RVOT VTI * π *

Is the Qp / Qs ratio a non-invasive method?

The Qp/Qs ratio is a non-invasive method for measuring systemic and pulmonary blood flow. High correlations were found between Fick- and Doppler-derived indexed measurements of systemic and pulmonary flow as well as the pulmonary to systemic flow ratio.