PF Ratio Calculator

p aO2  


p aO2 FIO2 Ratio  
Decimal Precision  

About PF Ratio Calculator

What is pf ratio?

The P/F ratio is an easy way to gauge how severe hypoxemia is. It is the ratio of arterial blood gas's FiO2 to arterial blood gas' PaO2 (arterial oxygen partial pressure) (fraction of inspired oxygen expressed as a decimal). The P/F ratio, for instance, is 475 for a person breathing room air (21% oxygen, or a FiO2 of 0.21), with a PaO2 of 100 mmHg. P/F is also used to stratify the severity of acute respiratory distress syndrome (ARDS) in accordance with the Berlin criteria and in various scoring systems, such as the APACHE-IV.

You can quickly calculate the P/F ratio to assist you and the medical staff in determining whether the patient has ARDS. Find your PaO2 first by looking at your blood gas and your ventilator's FIO2 (or from whatever oxygen delivery device you are using). In this illustration, let's assume that your PaO2 is 83 and that your ventilator's FIO2 setting is 45%. Your FIO2 should now be converted to a decimal, which is 0.45 in our example. Simply divide your PaO2 by your FIO2 at that point. It will seem as follows: 83/0.45 = 184. Anything below 300 is a sign of ARDS.

  • As mild ARDS, 300 to 200 is considered.
  • Moderate ARDS is defined as 200 to 100.
  • Any value under 100 is regarded as severe ARDS.

How to calculate pf ratio?

PaO2 (arterial pO2) from the ABG is represented by "P." The letter "F" stands for the fraction of inspired oxygen (FIO2), which is the percentage of inspired oxygen that the patient is receiving expressed as a decimal (40% oxygen = FIO2 of 0.40). P/F ratio = P/F divided by F.

What are some advantages and disadvantages of pf ratio?

Its extensive use is possibly due to how quick and easy it is. can serve as a general indicator of the presence of a strong A-a gradient. More useful than the a/A ratio because alveolar oxygen tension PAO2 measurement is not necessary. utilised in severity rating schemes.

Greater P/F ratios can not always translate into better results. P/F ratio is a tension-based measure that is reliant on barometric pressure. P/F ratio by itself is unable to differentiate between hypoxaemia brought on by alveolar hypoventilation (high PACO2) and other conditions like V/Q mismatch and shunt. strongly reliant on FiO2. does not take PEEP or mean airway pressure into consideration. necessitates the measurement of arterial blood gas. heavily reliant on oxygen extraction using CaO2-CvO2. does not represent the hemoglobin-dependent oxygen content of the blood or the transport of oxygen to tissues ( dependent on cardiac output and oxygen content).

What is the difference between hypoxia and hypoxemia?

It's crucial to understand the difference between hypoxemia and hypoxia. In relation to the oxygen concentration being inhaled, hypoxemia is defined as a SUBNORMAL concentration of oxygen in the blood.

Hypoxia is the medical term for tissues with insufficient oxygen levels. When caring for a patient with respiratory insufficiency or failure, it's important to keep the PaO2 and SpO2 above 60 and 90%, respectively, because those values should still be able to adequately oxygenate the tissues.

What a vq mismatch?

When a portion of your lung obtains oxygen without blood flow or blood flow without oxygen, a V/Q mismatch occurs. This occurs when a blood vessel or an airway becomes blocked, such as when you are choking or have a blood clot in your lung. Additionally, it may occur if a medical condition makes you breathe in but not expel oxygen or breathe in blood but not expel oxygen. A V/Q mismatch can result in hypoxemia, or low blood oxygen levels. Respiratory failure can occur when the blood oxygen level is inadequate.

V represents ventilation, or the air you breathe, in a V/Q ratio. Perfusion, or blood flow, is what the Q stands for, which is a little puzzling. The V/Q ratio is essentially equal to the ratio of the blood flow through your lungs' capillaries to the amount of air that reaches your lungs. The V/Q ratio is 0.8 when your lungs are working normally, with 4 litres of air entering your respiratory tract and 5 litres of blood passing through your capillaries each minute. V/Q mismatch is the term used to describe a higher or lower number.

Two different kinds of V/Q mismatch exist. Despite appropriate perfusion and ventilation, a dead gap prevents oxygen from reaching the bloodstream. A typical cause of dead space is a pulmonary embolism, which can be treated with oxygen therapy. Dead space is the polar opposite of shunt, on the other hand. This happens when the blood flow or perfusion is sufficient but the breathing is insufficient.

What is the difference between pao2 and oxygen saturation?

With a pulse oximeter, we can measure SpO2 noninvasively, but to detect PaO2, we must perform a blood gas study. Although monitoring SpO2 is a highly useful tool, it is not very sensitive. Simply said, PaO2 measures the real oxygen concentration in arterial blood. The pressure that a particular gas in a mixture of other gases exerts on the container walls is referred to as partial pressure. To put it another way, if a gas, like as oxygen, is present in a liquid, such as blood, as well as an air space, such as the lungs, and the air space and liquid come into contact with one another, the two partial pressures will equalise.

The percentage of Hemoglobin Hgb binding sites in the blood that are carrying oxygen is known as oxygen saturation. Oxygen is carried by haemoglobin, a chemical molecule found in red blood cells (RBCs), on particular binding sites. When completely saturated, each Hgb molecule can bind four oxygen molecules. How many of these binding sites are coupled, or saturated, with oxygen, can be counted. The oxygen saturation, or SPO2, is expressed as a percentage. When all of the Hgb binding sites are occupied, SpO2 and Hgb are completely saturated. Using the Oxy-Hemoglobin Dissociation Curve, you may determine your PO2 from the SPO2 if the reading is less than 100.