Acidemia and Acidosis


It is the term that describes the state of blood where pH is low. It is very tightly connected to the term Acidosis because physicians use them interchangeably and acidosis is process that leads to the state of acidemia.
One more term is used in opposite of acidosis and that is Alkalosis which represents high pH in blood that is also not good.


All these terms are used to determine the acidity or alkaloidity of blood plasma. Increased acidity means that in blood plasma is found increased hydrogen ion concentration.
Acidosis occures when arterial pH falls below 7.35 and Alkalosis occures when pH is higher than 7.45. In between 7.35-7.45 is normal saturation of pH in blood plasma.
In mammals the normal pH varies from 7.35 until 7.50 depending on species.Changes in the pH of arterial blood outside of this values results in unrepairable cell damage.


There are two main sorts of acidosis on humans. Those are respiratory acidosis and metabolic acidosis.

Respiratory acidosis
Respiratory acidosis is a result of a build up carbon dioxide CO2 in blood that occures because of hypo ventilation. It is oftenly caused by pulmonary problems, drugs like anaesthetics and sedatives, head injuries and brain tumors. It can also occur due to pneumothorax, asthma, chronic bronchitis, aspiration and severe pneumonia. It can also be present like response to chronic metabolic alkalosis.

The main difference between respiratory and metabolic acidosis is that respiratory acidosis shows that CO2 is increased while bicarbonate is either normal or increased. Compensation happens if respiratory acidosis is present and chronic phase is entered with partial buffering of the acidosis trough renal retention of bicarbonate.
In cases where chronic illness of pulmonary function persists (late stage emphysema or muscular dystrophy) compensatory mechanisms wont be able to reverse acidotic stage. Metabolic bicarbonate production will become exausted and infusion of external bicarbonate wont be able longer to reverse the extreme buildup of CO2 that is associated with uncompensated respiratory acidosis and mechanical ventilation will be applied usually.

Metabolic acidosis
Metabolic acidosis is an increased production of metabolic acids and it is usually a result of disturbances in the ability to excrete acid via kidneys. Renal acidosis is connected with accumulation of urea and creatinine as well as metabolic acid residues of protein catabolism. Increasing of the production of other acids can also be the cause of the appearance of metabolic acidosis.Acid consumption caused by poisoning is rising levels of iron in the blood and that chronically decreases production of bicarbonate and that can also be cause of metabolic acidosis.
Treatment of uncompensated metabolic acidosis is focused upon correcting the underlying problem. When metabolic acidosis is severe and can no longer be compensated for adequately by the lungs, neutralizing the acidosis with infusions of bicarbonate may be required.

Resources

Pocket Medicine: The Massachusetts General Hospital Handbook of Internal Medicine (Pocket Notebook Series)
The Acid-Alkaline Food Guide: A Quick Reference to Foods & Their Effect on pH Levels
First Aid for the USMLE Step 1 2009: A Student to Student Guide (First Aid USMLE)
Harrison's Principles of Internal Medicine, 17th Edition
Nurse Practitioner Certification Examination And Practice Preparation
CURRENT Medical Diagnosis and Treatment 2009 (LANGE CURRENT Series)