Respiratory alkalosis is a disturbance of the acid-base balance in the body, where the pH of the blood increases as a result of hyperventilation (increased respiratory rate). What are the causes and symptoms of respiratory alkalosis? How is the treatment going?

Respiratory alkalosisis an acid-base imbalance where the pH rises above normal (>7.45) and the primary cause of which is a drop in pCO 2 in the blood, that is, hypocapnia. It occurs as a result of excessive lung ventilation. Rapid breathing causes an excessive loss of carbon dioxide, which leads to the loss of "acidic" components in the blood and, ultimately, to the development of respiratory alkalosis. Hyperventilation can be controlled by a human, or autonomous, that is, independent of him. The causes of hyperventilation include:

  • stimulation of the respiratory center in the central nervous system, for example as a result of pain, stress, excitement, cold, neurosis - this is the so-calledpsychogenic alkalosis ;
  • hypoxia, i.e. hypoxia - here, however, hyperventilation is only temporary, it aims to bring the oxygen concentration to normal values, when it is ineffective, its mechanism disappears after some time;
  • irritation and stimulation of the respiratory system by toxins or allergens;
  • degenerative changes in the central nervous system, the vast majority of which are caused by vascular diseases;
  • mechanical ventilation;
  • drug overdose - the most common salicylates, as well as methylxanthines, theophylline;
  • pregnancy - hyperventilation is associated with hormonal changes (the influence of progesterone) and the adaptation of the mother's body to new conditions.

Symptoms of respiratory alkalosis

The clinical picture depends on the cause and the degree of hypocapnia - the lower the level of pCO2 , the more severe the symptoms will be. The patient will feel dizziness, tinnitus and will report the appearance of "scotomas" in front of the eyes.

Hypocapnia causes disturbances of consciousness, symptoms of cerebral ischemia, paresthesias (tingling sensation, numbness).

The so-called normocalcemic tetany also appears in respiratory alkalosis. The concept of tetany is mainlyassociated with hypocalcemia, i.e. a reduced level of calcium in the blood. In respiratory alkalosis, however, the mechanism of its formation is different, as it occurs, as a result of a reduced level of hydrogen ions in the blood, to the binding of calcium ions with plasma proteins. Bound calcium ions are inactive, so the body behaves as if it is deficient.

Tetany is manifested by numbness and spasms of various muscles, not only skeletal ones. This may include, but is not limited to, an asthma attack (bronchospasm), angina (spasm of the coronary arteries), abdominal pain (abdominal vasospasm), migraine attack, or loss of consciousness (spasm of the cerebral vessels).

Worth knowing

Acid-base balance of the body

Under physiological conditions, the parameters of the acid-base balance of the organism are as follows: blood pH: 7.35-7.45 Hydrogen ion concentration (H +): 35-45 nmol / l Partial pressure arterial carbon dioxide (pCO2): 35-45 mmHg

Criteria for the diagnosis of respiratory alkalosis

Due to the mechanism of alkalosis, it is necessary to diagnose hyperventilation - permanent or periodic. Blood pH is>7.45, pCO2 is reduced, and HCO3- level is normal (rarely slightly decreased) - we are talking about uncontrolled alkalosis. As previously mentioned, the kidneys are an important link in the regulation of the acid-base balance. When respiratory alkalosis develops, the pCO2 level is reduced, therefore the renal production and reabsorption of HCO3 decline. Carbon dioxide, which "prevented" elimination during hyperventilation, is not buffered by bicarbonate (because there is less of it), so the pH gradually drops and then remains within the normal range. In this case we are talking about balanced respiratory alkalosis.

respiratory alkalosispHpCO2HCO3
not aligned↑

↓

N
partially aligned↑

↓

↓
alignedN

↓

↓↓

N- norm ↓ - decreased ↑ - increased

Respiratory alkalosis: treatment

The most important element of treatment is always causal treatment. If the respiratory alkalosis is psychogenic in nature, efforts should be made to calm the patient. Breathing mixtures with an increased CO content can also be used2- for example breathing from a large plastic bag, because the exhaled carbon dioxide isretained in an enclosed space and can be reused by a sick person (so-called dead breathing space). Sometimes it is necessary to use sedatives, but this option should be left as the last resort. If hyperventilation is due to another cause, it should be effectively treated, e.g. by drug poisoning. An exceptional situation is the management of a patient with hypoxia - hyperventilation and alkalosis are an element of compensation here, therefore it cannot be inhibited. It is then necessary to find and treat the cause of hypoxia.

Worth knowing

Regulation of acid-base balance

Buffers present in the body are mixtures of weak acids and their basic s alts, which can bind excess hydrogen ions or give them back as needed. Thanks to this, they have the ability to neutralize acid or alkaline substances supplied exogenously (i.e. from outside) or produced in the body (endogenously), so that the blood pH is kept within the normal range. Another element necessary for the proper functioning of the acid-base balance are the lungs and the ventilation taking place in them. Blood pH depends on pCO2. When lung ventilation is slowed or inhibited, CO2 is not removed from the body and the blood pressure increases, which is called (respiratory) acidosis. The opposite is true during hyperventilation: more breaths result in excessive removal of carbon dioxide from the body, contributing to a decrease in pCO2 and the formation of (respiratory) alkalosis. The last link controlling blood pH are the kidneys, whose role is reduced to the excretion of H + as well as reabsorption and production of HCO3-, the main buffer in the body. If these processes are inhibited or limited in the kidneys, non-respiratory or metabolic acidosis will develop. It can be said that the kidneys are the last "lifeline" for the body, because at the final stage of metabolism, i.e. excretion, they can compensate for other, previously occurring processes, thanks to which the pH can be kept within the normal range all the time.

Acid-base imbalance

These disorders can be divided into respiratory and non-respiratory, in other words metabolic. The change in pCO2 value, which depends on the ventilation of the lungs, is responsible for the development of respiratory acidosis or alkalosis. In turn, metabolic disorders (acidosis and alkalosis) are related to the non-respiratory component, i.e. a change in the concentration of hydrogen, bicarbonate or other bases, which occurs as a result of various processes taking place inside the body.

Category:

Respiratory system