Enter your information to understand your CO2 levels.

The History of CO2

Understanding how the body buffers its internal chemistry began taking real shape in the early 20th century, when American biochemist Lawrence Henderson and Danish physician Karl Albert Hasselbalch independently developed the mathematical framework, published in stages between 1908 and 1917, describing how blood's acidity relates directly to the delicate balance between dissolved carbon dioxide and bicarbonate in the bloodstream at any given moment in time. Their combined work, now universally known as the Henderson-Hasselbalch equation, gave physicians their first genuinely quantitative way to understand blood's acid-base chemistry, transforming what had previously been a poorly understood physiological mystery into a solvable mathematical relationship clinicians could actually calculate and apply directly at the bedside during patient care and true medical emergencies.

What CO2 Actually Is

On a routine metabolic blood panel, the value labeled "CO2" mostly reflects bicarbonate, the primary chemical form carbon dioxide takes while circulating in the bloodstream, along with a very small additional amount of dissolved gas mixed in as well at any given time. Bicarbonate functions as the body's main chemical buffer, keeping blood pH locked within an extremely narrow, life-sustaining range despite constant metabolic activity happening throughout virtually every organ system at once, all day and night long. The kidneys regulate bicarbonate levels gradually over hours and days, while the lungs adjust the balance almost instantly by controlling how quickly carbon dioxide gas is exhaled with each individual breath taken, making CO2 a genuinely joint product of both organ systems working together continuously around the clock, day and night, without ever pausing.

How CO2 Is Measured

Modern automated chemistry analyzers measure total CO2 using an enzymatic method in which the enzyme phosphoenolpyruvate carboxylase reacts with bicarbonate in the blood sample, triggering a coupled reaction that consumes a light-absorbing compound called NADH in direct proportion to the amount of bicarbonate present in that particular sample being analyzed carefully. A spectrophotometer then precisely measures that resulting change, calculating the final concentration within moments of the sample first being loaded into the machine for testing purposes. This modern approach has largely replaced older manual titration techniques and specialized gas-sensing electrodes that earlier generations of laboratory technicians once relied upon daily for this exact purpose in hospitals everywhere.

Scientists Behind the Science

Lawrence Henderson's foundational work on blood chemistry and physiological buffering systems provided much of the essential conceptual groundwork later refined into a precise, genuinely usable equation for real clinical purposes in hospitals everywhere around the world. Karl Albert Hasselbalch's parallel contributions in Denmark helped transform Henderson's underlying physiological insights into the practical mathematical formula still taught to every single medical student today, more than a century after it was first developed by both men together. Together, their combined work — developed independently on two entirely different continents before eventually converging into a single unified equation — remains the essential foundation for how doctors interpret CO2 and bicarbonate results in the context of a person's overall acid-base balance, still directly relevant in every intensive care unit worldwide today, without any exception whatsoever.