Blood gas analysis is a diagnostic tool to evaluate the partial pressures of gas in blood and acid-base content. The use of blood gas analysis enables to clear understanding the respiratory, circulatory, and metabolic disorders. The arterial blood gas (ABG) explicitly analyzes blood taken from an artery, assessing the patient's partial pressure of oxygen (PaO2), carbon dioxide (PaCO2) pH (acid/base). PaO2 indicates the oxygenation status, and PaCO2 indicates the ventilation status (chronic or acute respiratory failure). PaCO2 is affected by hyperventilation characterized by rapid or deep breathing, and hypoventilation characterized by slow or shallow breathing. The acid-base balance tested by the ABG procedure measures the pH and PaCO2 directly while the use of the Hasselbach equation gives the serum bicarbonate (HCO3) and base deficit or excess. The measured HCO3is based on strong alkali that frees all CO2 in serum, including dissolved CO2, carbamino compounds, and carbonic acid the calculation uses a standard chemistry analysis giving the amount of "total CO2", the difference will amount to around 1.2 mmol/L. Though ABG is frequently ordered in emergency medicine contests for acute conditions it may also be needed in other clinical settings. The ABG analysis shows to be an exceptional diagnostic tool including the group of those diseases known as acid-base diseases (ABDs) which include a great variety of conditions as such severe sepsis, septic shock, hypovolemic shock, diabetic ketoacidosis, renal tubular acidosis, chronic respiratory failure, chronic heart failure, and diverse metabolic diseases.