• Acidosis

• Normal blood and most tissues have a near neutral pH. "Neutral" is neither acidic or basic.
• When a person has acidosis he or she is called "acidotic", or is said to have (or be in) an "acidotic state".

There are two general kinds of acidosis, that are determined by the means that the skewed pH is generated. In other words, these kinds of acidosis indicate how the blood ended up getting an excess of hydrogen ions.

• Respiratory Acidosis: comes about when the lungs are not adequately ridding the body of carbon dioxide (which, dissolved in blood, is acidic). The blood pH is low because there is lots of disassociated hydrogen ions, the blood concentration of CO2 (bicarbonate is high).
• Metabolic Acidosis: comes about from a variety of reasons, all sharing the common factor of a low amount of the negative ions, like bicarbonate, that balance the acidic hydrogen ions.
• Compensation:
  • If there is long term metabolic acidosis, the blood pH may be near normal because of respiratory compensation - in this case rapid breathing "blows off" carbon dioxide.
  • Similarly, if there is long term respiratory acidosis, that occurs because of chronic retention of carbon dioxide, the blood pH may be near normal because the kidneys or other organs retain extra base (bicarbonate ion) to compensate. This sort of metabolic compensation is seen in heavy smokers with obstructive lung disease - as one example.

• When tissues are hypoxic (oxygen too low), an excess of acid results from anaerobic metabolism (biochemical reactions that run in alternate pathways where oxygen is not used) and from cell injury and death: pH drops. This is a metabolic acidosis.
• Additionally, when a person is not breathing (or barely breathing), carbon dioxide cannot be adequately blown off, and respiratory acidosis results.
• That's why, after major trauma resulting in shock, or after resusitation from cardiac arrest, acidosis is to be expected. Both metabolic and respiratory procesess are unbalanced, driving blood from a near neutral to an acid pH.

• Holcomb JB. Damage control resuscitation. Journal of Trauma-Injury Infection & Critical Care. 62(6 Suppl):S36-7, 2007 Jun
• Roderick P. Willis NS. Blakeley S. Jones C. Tomson C. Correction of chronic metabolic acidosis for chronic kidney disease patients. Cochrane Database of Systematic Reviews. (1):CD001890, 2007
• Englehart MS. Schreiber MA. Measurement of acid-base resuscitation endpoints: lactate, base deficit, bicarbonate or what?Current Opinion in Critical Care. 12(6):569-74, 2006 Dec.
• Schwartz GJ. Al-Awqati Q. Role of hensin in mediating the adaptation of the cortical collecting duct to metabolic acidosis. Current Opinion in Nephrology & Hypertension. 14(4):383-8, 2005 Jul
• Ni Chonghaile M. Higgins B. Laffey JG. Permissive hypercapnia: role in protective lung ventilatory strategies. Current Opinion in Critical Care. 11(1):56-62, 2005 Feb.

Medline Plus- Article on Acidosis

• Encyclopedia Article

• Acidosis and Alkalosis