- Symptoms
- Respiratory
- Cardiovascular
- Neurological
- General symptoms
- Causes
- Increased CO production
- CO removal failure
- Respiratory system
- Nervous system
- Muscle or neuro-muscular diseases
- Metabolic
- Other causes
- Increased CO inhalation
- Treatment
- References
The hypercarbia is the medical term refers to increasing the partial pressure of carbon dioxide (PaCO 2) levels. The normal values of PaCO 2 are between 35 and 45 mmHg, but certain clinical conditions cause its 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 -CO 2 - is a product of cellular metabolism, specifically of energy production processes.
Alveolar gas exchange. By domdomegg, from Wikimedia Commons
Both PaCO 2 and the partial pressure of oxygen -PaO 2 - remain in equilibrium, where the latter predominates. Furthermore, 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 implies the simultaneous existence of hypoxemia or a decrease in PaO 2 in the blood. Additionally, the increase in PaCO 2 produces respiratory acidosis, since it is a determining factor in acid-base balance.
Symptoms
The clinical picture of hypercarbia includes both the symptoms of CO2 poisoning and symptoms of the triggering diseases. Furthermore, due to the inverse relationship of O 2 / CO 2, it is possible to find symptoms of hypoxemia.
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:
Respiratory
- Increase of the respiratory frequence. In addition, it is observed that each inspiration is deeper.
- Dyspnea, as occurs in COPD and bronchial asthma.
- Abnormal breath sounds, such as crackles, rhonchi and wheezing.
Cardiovascular
- 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.
Neurological
- Dizziness and / or confusion.
- Headache, caused both by the accumulation of CO 2 and the decrease in O 2.
- Alteration of the state of consciousness, ranging from drowsiness to coma.
- Seizures.
General symptoms
- Blurry vision.
- Hearing loss
- Panic attacks.
- Feeling of imminent death.
- Muscle fasciculations, tremor or myoclonus.
- Diaphoresis.
Causes
Adequate respiratory function requires the participation of both the respiratory system - airways and lungs - and the metabolic, muscular and nervous systems. Any alteration in these systems implies a decrease in respiration or accumulation of CO 2.
From a functional point of view, hypercarbia is a consequence of the increased production of metabolic CO 2, as well as the difficulty to eliminate it.
Respiratory system dysfunction is one of the causes of CO 2 accumulation in the body. Furthermore, another rare mechanism is exposure to high levels of environmental CO 2.
An increase in the levels of CO 2 in the blood activates the regulatory mechanisms to favor its elimination. This implies the increase in both respiratory frequency and depth to enter oxygen and remove CO 2 from the body. In addition, both the nervous system - respiratory center - and the muscular system intervene in this mechanism.
Increased CO production
There are several circumstances that induce an increase in carbon dioxide production, and they are related to altered metabolism. Hypercapnia, in this case, is compensated by an increase in CO2 removal. The following are metabolic causes of hypercarbia:
- Sepsis. Infectious processes -especially acute- increase catabolism and cause elevation of PaCO 2.
- Increased basal metabolism, as occurs in thyrotoxicosis linked to hyperthyroidism.
- Metabolic acidosis.
- Extensive bodily trauma.
- Strenuous physical exercise.
- Fever.
- Prolonged use or high doses of steroids.
- Supercharging.
- Administration of oxygen in chronic obstructive pulmonary disease (COPD).
CO removal failure
All the pathologies that imply dysfunction of the systems related to the respiration suppose a decrease in the elimination of CO 2. The most commons are:
Respiratory system
- Chronic obstructive pulmonary disease.
- Bronchial asthma.
- Respiratory infections, such as bronchitis and pneumonia.
- Pulmonary embolism
- Sleep apnea.
Nervous system
- Head injuries with cerebral edema.
- Infections of the nervous system, such as meningitis or encephalitis.
- Cerebrovascular disease.
- Intoxication by depressant drugs of the nervous system, such as benzodiazepines and opioids.
Muscle or neuro-muscular diseases
- Myopathies, such as muscular dystrophies.
- Gillian Barré syndrome.
- Myasthenia gravis.
- Amyotrophic Lateral Sclerosis.
Metabolic
- Diabetic cetoacidosis.
- Kidney diseases including renal tubular acidosis.
- Hypophosphatemia.
- Hypomagnesemia.
Other causes
Free diving and scuba diving.
Obesity-induced respiratory distress, the cause of which is mechanical.
Malpractice in improperly setting mechanical ventilation parameters.
Increased CO inhalation
- Occupational accidents, especially in industries where CO 2 is stored.
- Stay in confined spaces with little oxygen. In this case, when the oxygen reserve is exhausted, the individual rebreathes the CO 2 expelled.
- Inhalation of gases from geothermal sources or volcanic eruptions.
Treatment
First, the respiratory process provides a necessary and sufficient amount of O 2 to perform vital functions. The amount of O 2 and CO 2 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 supply of O 2 in sufficient quantity. The administration of oxygen, which must be humidified, is done by a mask or nasal mustache, according to the requirements. The patient should be monitored, monitoring parameters such as O 2 saturation and capnography.
Another method of monitoring in case of hypercarbia is arterial blood gas, providing accurate data not only about the partial pressure of gases but also the acid-base balance in the body.
References
- Rawat, D; Sharma, S (2018). Hypercapnea. Recovered from ncbi.nlm.nih.gov
- Leonard, J Rev by Falck, S. (2018). What to know about hypercapnia. Recovered from medicalnewstoday.com
- Leader, D (2018). An overview of hypercapnia: causes, treatment, and association with copd. Recovered from verywellhealth.com
- Hall, JB; McShane, PM (nd). Respiratory insufficiency. Recovered from msdmanuals.com
- McKinney, W (2015). Hypercapnia: causes. Recovered from openanesthesia.org
- Russel, L (sf). Hypercarbia: Symptoms & Treatment. Recovered from study.com
- Rakhimov, A (Last act 2018). CO2, blood pH and respiratory alkalosis. Recovered from normal respiration.org
- Rakhimov, A (Last act 2018). Hypercapnia: the causes and treatment. Recovered from breathing normal.org.