A newly posted junior doctor had difficulty in finding out base deficit/excess for blood in a given patient. An experienced senior resident advised a quick method to determine acid base composition of blood based on pCO2. Which of the following is the likely method he suggested to predict acid base composition of blood

Ref: Ganong 19/e p703 fig 39.8   Siggard-Anderson nomogram: plots the acid-base charecteristics of arterial blood PCO2 is placed on the vertical axis and pH on the horizontal axis Vertical line through pH 7.40: any point to the left denotes acidosis & any point to right denotes alkalosis Horizontal line through p CO2 of 40 mmHg: point above or below this line defines the effective degree of hypo or hyperventilation