The breathing, although it has its nucleus of operation in the lungs, affects the functioning of the whole organism. Your goal is achieve adequate amounts of oxygen in the blood (O2) and carbon dioxide (CO2).
That is precisely what is discussed in this article. To understand the first symptoms of respiratory failure, we will first make a brief review about what it is.
Physiology of breathing
The respiratory movements are inspiration, introduction of air into the lungs, and expiration, expulsion (not to be confused with the expiration that refers to death!).
During inspiration, oxygen (along with all other gases that make up the air) is introduced into the lungs. This oxygen passes from the lungs to arteries , and from there to the cells.
Each cell, using oxygen (each performing its specific function) converts it to CO2. This goes to the veins, in this case to the pulmonary vein, and is eliminated with expiration.
How breathing is measured
Respiratory function It is measured with several parameters, but the ones that occupy us at this moment are the partial pressures and the respiratory frequency.
- The partial pressures they allow us to calculate how much of a gas there is in the individual’s blood. It can refer well to arterial blood or venous blood. Look at millimeters of mercury (mmHg)
- Breathing frequency: quantifies how many cycles inspiration-expiration They occur in a minute. The higher the respiratory rate, the more CO2 will be eliminated.
What is respiratory failure?
Respiratory failure is characterized as altered values of O2 and CO2 in arterial blood. The normal partial pressures of oxygen and CO2 are as follows:
- Normal partial oxygen pressure (PaO 2 ): from 75 to 100 mmHg
- Normal partial pressure of carbon dioxide (PaCO 2 ): from 38 to 42 mmHg
It could be said, then, that one of the first symptoms of respiratory failure is the variation of these partial pressures. By definition in respiratory failure a depression of respiratory function occurs. We can conclude that it occurs:
- Decrease in PaO 2 for less inspiration: PaO 2 less than 75 mmHg
- Increase of the PaCO 2 by decreasing respiratory rate: PaCO 2 greater than 42 mmHg
Pathologies that can cause respiratory failure
As we have seen, respiratory failure is not a pathology in itself. It is rather consequence of pathologies that affect respiratory function. Some examples are:
- Diseases of the lungs
- Overdose of narcotics and alcohol (they produce drowsiness)
- Lesions in the bones and tissues around the lungs
- Weakness of respiratory muscles
- Obstruction of the airway
Each of these pathologies will have specific symptoms. We will not develop them at this time because they are not strictly secondary to respiratory failure.
First symptoms of respiratory failure
We will comment first dyspnea. It refers to the subjective sensation of difficulty in breathing. It is produced by the lack of oxygen. It is accompanied by restlessness and anxiety, secondary also to the lack of oxygen.
The lack of oxygen it also causes cyanosis, bluish coloration of the skin, and also of nails and mucous . Our skin is more or less pink due to the red coloration of the blood. The red color is given to the blood hemoglobin , protein that transports oxygen, when it is attached to it.
The less oxygen there is in the blood, the less hemoglobin binds to it, and the blood will be less red. So the cyanosis translates the darkening of the secondary blood to the lack of oxygen.
It shows also tachypnea: this term means rapid breathing (not to be confused with dyspnea). It is a reaction of the organism, which tries to eliminate carbon dioxide (increasing the respiratory rate). It will not work if, because of the underlying pathology, the lungs or respiratory muscles are damaged.
The role of the sympathetic nervous system
Everything together activates the sympathetic nervous system , the fight or flight system. It is activated when we are presented with a dangerous situation (in this case, the lack of oxygen). Promotes either of the two reactions mentioned above, which are the two possibilities we have before any stress.
So, activate a series of mechanisms that start or alert the body. In the context of the first symptoms of respiratory failure we find tachycardia and diaphoresis.
The tachycardia is the incrise of cardiac frecuency. It is the heart that pumps the blood to the cells, and therefore, is responsible for oxygen reaching all of them.
The organism try to make up for the lack of oxygen by getting more blood per unit of time to each cell, by tachycardia. An increase in sweating appears. It is what is known as diaphoresis.