Respiratory Acidosis || Decreased pH and Increased CO2 in the Blood

Respiratory Acidosis, that's what I will be discussing today in a very simple yet extensive way. According to the name, Acidosis refers to a condition where blood pH is lowered below 7.35, and when it has to do with respiratory acidosis, then it has to do with the respiratory system failing to perform pH balancing. . With this, a simple way to explain it will be; if there is a result from an ABG which shows a patient's arterial blood gas test comes back showing a low pH below 7.35 showing acidemia, and an increased CO2 (greater than 45mmHg). In this case, we can also add to the test result that the patients could be suffering from hypoxia. With this test result, it is visible that the patient has low oxygen in the blood, reduced pH, and increased CO2 which is what we need to define respiratory Acidosis.

Let's quickly explain how respiration works in the brain, a quick physiology would help. In the medulla, at the region of the nucleus ambiguus and retro ambigualis are the Ventral respiratory group, and the Dorsal respiratory group, which are neurons that impact the rate and depth of breathing. These neurons send signals to the lower motor neurons of C3 and C5 which then innervates the muscles of breathing which are the diaphragm, the intercostal muscles causing them to contract to bring in oxygen and relaxing, thereby releasing carbon dioxide. ,,. During respiratory acidosis, the CO2 in the blood increases and the pH decreases, since CO2 is hardly exhaled and less oxygen getting into the blood.

This problem can begin from the respiratory center in the medulla as a result of a lesion that could be caused by infection, trauma, or as a result of drugs such as Opioids, benzodiazepine inhibiting and suppressing the medulla from functioning properly. ,,. The problem could also begin in the anterior gray horn neurons in the spinal cord as a result of lesions, Sclerosis (ALS), diseases such as poliomyelitis, transverse myelitis, or demyelination of the myelin sheath, or cases of Autonomic dysfunction. ,. The Neuromuscular junction is another place to check because, at the junction, acetylcholine is produced which acts on the muscles of respiration by binding to the nicotinic receptors in the muscle but with issues in the junction such as underlying conditions such as myasthenia gravis which is an autoimmune condition that causes antibodies to target the receptors that the acetylcholine from the sheath is trying to bind to thereby inhibiting the binding of acetylcholine and the nicotinic receptors thereby preventing the muscles from contracting which will cause a reduction in oxygen and an increase in carbon dioxide. This can be caused by Thymoma and auto antibodies that attack the nicotinic receptor. There can be possibilities that the muscle of respiration is the cause for respiratory acidosis. If the muscles are exhausted as a result of increased hard work with breathing overtime as a result of an underlying respiratory illness. Patients who suffer from polymyositis can also suffer from Respiratory Acidosis.,,. The issue might not be the muscles but rather the lungs. If there are blockage in the airway either via mucus or foreign body, or collapsing of the airway. This could be as a result of COPD which blocks the airways and not allowing air out, thereby increasing the carbon dioxide available in the blood. It can also be as a result of an upper respiratory tract blockage, or a laryngeal edema, it can lead to low release of carbon dioxide thereby causing more CO2 in the blood.. Mucos in the airway and fluid in the airway is another reason for respiratory acidosis as oxygen intake into the blood is reduced. Conditions such as pneumonia, Acute respiratory distress syndrome (ARDS), pulmonary edema, and pulmonary embolus can lead to less oxygen getting into the blood which can lead to hypoxia, causing increased CO2 and a decreased pH.,.

Patients with Respiratory acidosis are usually treated by treating the underlying conditions. If the underlying issue is fixed, it should take care of the respiratory acidosis. If there is a lesion in the medulla then resecting the lesion through surgery, using steroids, cases of encephalitis would be treated with antibiotics, when patiets have opioid overdose, they are treated with naloxone. In cases of hypothyrodism, they should be treated with levothyroxine or other thyroid hormones, hypothermic patients should be warmed up. In cases of Guillain–Barre Syndrome (GBS), patients can be treated with IVIg. Patients who also have underlying causes being myasthenia gravis they can be treated with plasmaphoresis or IVIg. In cases of exhaustion there can be non-invasive pressure ventilation, fluid therapy, and invasive mecanical ventilation. Cases of COPD will require treatment such as inhaled corticosteroids, Duoneb Ampul, and non-invasive pressure ventilation. Basically, with respiratory acidosis, it is important to treat the underlying issues, and when patients are exhausted, supporting their respiratory system is important.,,,,,.

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