What is the appropriate concentration of inhaled oxygen during the operation?

For a patient without lung disease, what is the inhaled oxygen concentration setting during general anesthesia? 70% ? 50% ? 30% ? Or 100%
.

For a patient without lung disease, what is the inhaled oxygen concentration setting during general anesthesia? 70% ? 50% ? 30% ? Or 100%
.

With the discovery of a large number of studies, inhalation of high concentrations of oxygen significantly increases the incidence of perioperative atelectasis under the condition of ensuring sufficient oxygenation.
This fact should have been accepted by all anesthesiologists
.

So, how much should the intake oxygen concentration be maintained during the operation? If the oxygen concentration cannot be adjusted directly, what is the appropriate mixing ratio of air and oxygen?

With the discovery of a large number of studies, inhalation of high concentrations of oxygen significantly increases the incidence of perioperative atelectasis under the condition of ensuring sufficient oxygenation.

1.

The former responds by the partial pressure of oxygen ( PaO2 ) in the blood gas, and the latter can simply and directly monitor the percutaneous finger pulse oxygen saturation ( SPO2 ) during the operation

By consulting books and studying the oxygen ionization curve, we can get: Under normal circumstances, when the SPO2 is 99%-100% , PaO2 is about 160mmHg (this data comes from the data of conscious and spontaneous breathing patients, and the atelectasis after general anesthesia It may be necessary to appropriately increase PaO2 )

Data from "Modern Anesthesiology"

Data from "Modern Anesthesiology"

2.
The question now is, how much inhaled oxygen concentration ( FiO2 ) can just reach PaO2=160mmHg ?

2.
The question now is, how much inhaled oxygen concentration ( FiO2 ) can just reach PaO2=160mmHg ?

Continuing the analysis, we know that the oxygenation index of the normal human lung is 400-500 , where the oxygenation index =PaO2/FiO2
.

It is calculated that the theoretically inhaled oxygen concentration =160/500-160/400 , which is 32%-40%!

Continuing the analysis, we know that the oxygenation index of the normal human lung is 400-500 , where the oxygenation index =PaO2/FiO2

Normally, pure oxygen inhalation is used in anesthesia, but long-term application is prone to oxygen poisoning and atelectasis after anesthesia.
Advanced units have switched to inhalation with an oxygen concentration of 0.

After using the lung capacity method to reopen the previously collapsed lung tissue and inhaling pure oxygen for mechanical ventilation, atelectasis will recur immediately

So far, both theory and practice have proved that under normal circumstances, FiO2 can meet the oxygenation needs at 30%-40% , and it can significantly reduce the incidence of atelectasis after intraoperative pulmonary expansion

Of course, each patient's condition during the operation is different, and it may not be reasonable to require an oxygen concentration of 40% .
Therefore, I propose the following method to titrate the inhaled oxygen concentration that is most suitable for the patient (the following method is best performed after expanding the lung):

1.

2.

In addition, some low-end anesthesia machines in China can only suck pure oxygen, and some can perform air-oxygen mixing, but cannot directly adjust the oxygen concentration.

Air: oxygen = 1:1 inhaled oxygen concentration is about 60% ; 2:1 inhaled oxygen concentration is about 47% ; 3:1 inhaled oxygen concentration is about 40%

Summarize the following:

1.
Under no special circumstances, the inhaled oxygen concentration for both lung ventilation is best maintained at 30%-40% ( 40% is recommended , at least 50% or less)
.
If the pulse oxygen saturation cannot be maintained, the inhaled oxygen concentration can be titrated after the lung can be inflated
.

1.
Under no special circumstances, the inhaled oxygen concentration for both lung ventilation is best maintained at 30%-40% ( 40% is recommended , at least 50% or less)
.
If the pulse oxygen saturation cannot be maintained, the inhaled oxygen concentration can be titrated after the lung can be inflated
.

2 , can not be directly adjusted by the concentration of oxygen, air and oxygen mixing ratio of 3: 1 or so more appropriate
.

2 , can not be directly adjusted by the concentration of oxygen, air and oxygen mixing ratio of 3: 1 or so more appropriate
.

It is worth noting that the appropriate reduction of inhaled oxygen concentration should be based on sufficient oxygen partial pressure.
Oxygenation is far more important than atelectasis
.
Especially in one-lung ventilation or combined with lung disease, pure oxygen may be difficult to maintain satisfactory oxygen partial pressure and saturation
.

It is worth noting that the appropriate reduction of inhaled oxygen concentration should be based on sufficient oxygen partial pressure.
Oxygenation is far more important than atelectasis
.
Especially in one-lung ventilation or combined with lung disease, pure oxygen may be difficult to maintain satisfactory oxygen partial pressure and saturation
.

Although hard work in the clinic for many years, but to inspired oxygen patients were 50% more, never down to 50% or less
.
In this article, through independent thinking and review, it is found that foreign countries have already adopted lower concentration oxygen inhalation
.
Your own cognition has also been upgraded, and I hope it will be rewarding for you!

Although hard work in the clinic for many years, but to inspired oxygen patients were 50% more, never down to 50% or less
.
In this article, through independent thinking and review, it is found that foreign countries have already adopted lower concentration oxygen inhalation
.
Your own cognition has also been upgraded, and I hope it will be rewarding for you! Leave a message here