[What you should know of the arterial blood gases during the watch].

Gasometry is the measurement of dissolved gases in the blood, by measuring pH, carbon dioxide pressure (pCO(2)), serum bicarbonate (HCO(3-)), and lactate and serum electrolytes: sodium, potassium and chlorine you can make a diagnosis, etiology and treatment in the critically ill patient. The aim is to provide five steps for the interpretation of blood gases by: 1. The definition of acidemia or acidosis, or alkalemia or alkalosis. 2. Defining the metabolic component or respiratory. 3. To determine the anion gap; levels above 15 ± 2 determine other likely causes of excess anions (methanol, uremia, diabetic ketoacidosis, paraldehyde, ionized, lactic acidosis, ethylene glycol and salicylates. 4. Compensation, using the Winter formula. 5. The delta gap, with the formula for determining intrinsic and metabolic alkalosis. When anion gap is normal, is calculated urinary anion gap; the value is negative if the loss is extrarenal, contrary to the positive result is renal etiology.