The hypercarbia is the medical term for increased partial pressure of carbon dioxide (PaCOtwo) in blood. Normal PaCO valuestwo they are between 35 and 45 mmHg, but certain clinical conditions cause their increase. It is also known as hypercapnia.
The human body requires oxygen, in addition to nutrients, to perform all of its vital functions. on the other hand, carbon dioxide -COtwo- it is a product of cellular metabolism, specifically of energy production processes.
Both the PaCOtwo as the partial pressure of oxygen -PaOtwo- they are kept in balance, where the latter predominates. In addition, the stability of the partial pressures of gases guarantees the adequate supply of oxygen to the tissues and intervenes in the acid-base balance..
In any case, hypercarbia supposes the simultaneous existence of hypoxemia or decrease in PaOtwo in blood. Additionally, the increase in PaCOtwo produces respiratory acidosis, as it is a determining factor in acid-base balance.
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The clinical picture of hypercarbia includes both the symptoms of CO2 poisoning and symptoms of the triggering diseases. Furthermore, by the inverse relation of Otwo/COtwo, symptoms of hypoxemia may be found.
Initially, elevated PaCO2 usually has few symptoms, due to rapid respiratory compensation. An increase in the frequency and depth of respiration is sufficient as a regulatory mechanism. The persistence of hypercarbia produces alterations that cause the clinical picture:
- Increase of the respiratory frequence. In addition, it is observed that each inspiration is deeper.
- Dyspnoea, as occurs in COPD and bronchial asthma.
- Abnormal breath sounds, such as crackles, rhonchi, and wheezing.
- Tachycardia and elevation of blood pressure. Changes at the circulatory level occur to increase the flow of oxygen -decreased- to the tissues.
- Arrhythmias, due to cardiovascular compensation mechanisms, or changes due to hypoxemia.
- Dizziness and / or confusion.
- Headache, caused both by the accumulation of COtwo as the decrease in Otwo.
- Altered state of consciousness, ranging from drowsiness to coma.
- Seizures.
- Blurry vision.
- Hearing loss
- Panic attacks.
- Feeling of impending doom.
- Muscle twitching, tremor, or myoclonus.
- Diaphoresis.
Adequate respiratory function requires the participation of both the respiratory system - airways and lungs - as well as the metabolic, muscular and nervous systems. Any alteration in these systems supposes a decrease in respiration or accumulation of COtwo.
From a functional point of view, hypercarbia is a consequence of increased CO productiontwo metabolic, as well as the difficulty to eliminate it.
Respiratory system dysfunction is one of the causes of CO accumulationtwo in the body. In addition, another rare mechanism is exposure to high levels of CO.two environmental.
An increase in CO levelstwo in blood it activates the regulatory mechanisms to favor its elimination. This implies an increase in both respiratory frequency and depth to enter oxygen and remove CO.two of the organism. In addition, both the nervous system -respiratory center- and the muscular system intervene in this mechanism..
There are several circumstances that induce increased carbon dioxide production, and they are related to altered metabolism. Hypercapnia, in this case, is offset by increased CO2 removal. The metabolic causes of hypercarbia are:
- Sepsis Infectious processes -especially acute- increase catabolism and cause elevation of PaCOtwo.
- Increased basal metabolism, as occurs in thyrotoxicosis linked to hyperthyroidism.
- Metabolic acidosis.
- Extensive bodily trauma.
- Strenuous physical exercise.
- Fever.
- Long-term use or high doses of steroids.
- Supercharging.
- Oxygen administration in chronic obstructive pulmonary disease (COPD).
All the pathologies that imply dysfunction of the systems related to respiration suppose a decrease in the elimination of COtwo. The most commons are:
- Chronic obstructive pulmonary disease.
- Bronchial asthma.
- Respiratory infections, such as bronchitis and pneumonia.
- Pulmonary embolism
- Sleep apnea.
- Head trauma with cerebral edema.
- Nervous system infections, such as meningitis or encephalitis.
-Cerebrovascular disease.
- Nervous system depressant drug poisoning, such as benzodiazepines and opioids.
- Myopathies, such as muscular dystrophies.
- Gillian Barré syndrome.
- Myasthenia gravis.
- Amyotrophic Lateral Sclerosis.
- Diabetic cetoacidosis.
- Kidney diseases including renal tubular acidosis.
- Hypophosphatemia.
- Hypomagnesemia.
Freediving and scuba diving.
Obesity-induced respiratory distress, the cause of which is mechanical.
Malpractice in improperly setting mechanical ventilation parameters.
- Occupational accidents, especially in industries where CO is storedtwo.
- Stay in confined spaces with little oxygen. In this case, when the oxygen reserve is exhausted, the individual rebreathes the COtwo expelled.
- Inhalation of gases from geothermal sources or volcanic eruptions.
First, the respiratory process provides an amount of Otwo necessary and sufficient to perform vital functions. The amount of Otwo and COtwo they must remain in balance for the body to function properly. When carbon dioxide increases, carbon oxygen decreases in the blood.
Treatment of hypercarbia is intended to restore the balance that is lost. First, the specific cause of the condition must be diagnosed before starting treatment..
If it is a systemic disease - respiratory, nervous system or metabolic - the appropriate treatment will be established. Preventable causes, such as diving and risky work activity must be taken into account. The management of mechanical ventilation must always be carried out by properly trained personnel..
The main axis of the treatment of hypercapnia is the contribution of Otwo in sufficient quantity. The administration of oxygen, which must be humidified, is carried out by a nasal mask or mustache, according to the requirements. The patient should be monitored, monitoring parameters such as O saturationtwo and capnography.
Another method of monitoring in case of hypercarbia is the arterial blood gas, providing accurate data not only about the partial pressure of gases but also the acid-base balance in the body..
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