The IV Pole Top
The IV Pole Base
Acid-Base Balance

by "Grog" (Alan W. Grogono), Professor Emeritus, Tulane University Department of Anesthesiology

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High Altitude Acid-Base Diagram.

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High Altitude IconWhen you're young and you're striving, it's all uphill, and it's easier to climb. Then, when you get and look around, you sort of say, 'Wow, the altitude's kinda thin up here!' Ron Howard.
Acid-Base Balance Diagram: All the Typical Zones
Acid-Base Balance Diagram: All the Typical Zones

Acid-Base Balance Diagram: All the Typical Zones

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High Altitude and Sea Level: This diagram shows the relationship between the blood's acidity (pH), respiration component (PCO2), and metabolism component (Base Excess). The body's response varies with altitude. At lower altitudes (below a threshold of 1500 meters or 4920 feet) choose the Sea Level Diagram that uses a normal PCO2 of 40 mmHg (5.33 pPa). At higher altitudes choose this High Altitude Diagram that uses a "normal" PCO2 appropriate for the altitude (See Notes Below).

Enter Altitude beside the units you use for PCO2;
(low altitudes produce the Sea Level Diagram):

Enter Your Altitude:
For PCO2 in mmHg:    
For PCO2 in kPa:    


Sea Level

Sea Level Standard Base Excess
Sea Level Standard Base Excess

Sea Level Standard Base Excess

High Altitude

High Altitude Base Excess
High Altitude Base Excess

High Altitude Base Excess


  1. I am deeply indebted to Iván Solarte MD, MHPE. Full Professor, School of Medicine, Pontificia Universidad Javeriana, Respiratory Medicine Unit, Hospital Universitario San Ignacio. Bogotá Colombia. He persuaded me to modify the original sea-level version. Neither of us appreciated the magnitude of this undertaking; it occupied me for several weeks. In addition to his stimulus, he provided diagrams and equations, as well as several helpful ideas and corrections.


  1. 1Zubieta-Calleja G,Jr, Paulev PE, Mehrishi JN, * and Zubieta-Calleja G,Sr. Extremely high altitude hypoxic conditions during Mount Everest expeditions, residence at South Pole stations, in Tibet and among the Andes: Van Slyke equation modification is crucially important for acid–base measurements. Journal of Biological Physics and Chemistry 2012; 12:103-112.
  2. 2Barcroft J. The Respiratory function of the blood. Part I. Lessons from high altitudes. 1925; Cambridge University Press, Cambridge, UK.
  3. 3 Zubieta-Calleja G, Zubieta-Calleja L, Ardaya-Zubieta G, and Paulev PE. Do Over 200 Million Healthy Altitude Residents Really Suffer from Chronic Acid–Base Disorders? Indian J Clin Biochem 2011; 26(1):62–65.
  4. 4West JB. High Life. Association of Hospital Altitude and Postoperative Infectious Complications After Major Operations. Aasen DM, Wiedel C, Maroni P, Cohen ME, Meng X, and Meguid RA. High Altitude Medicine & Biology 2019; Dec:421-426. (
  5. 5Ezzati M, Horwitz MEM, Thomas DSK, Friedman AB, Roach R, Clark T, Murray CJL, Honigman B. Altitude, life expectancy and mortality from ischaemic heart disease, stroke, COPD and cancers: national population-based analysis of US counties. J Epidemiol Community Health 2012; 66:e17–e17.
  6. 6Zubieta-Calleja GR, Zubieta-DeUrioste NA. Extended longevity at high altitude: Benefits of exposure to chronic hypoxia. BLDE University Journal of Health Sciences 2017; 2:2:80-90.
  7. 7Acevado LE, Solarte I. Gasimetria arterial en adultos jovenes a nivel de Bogata. Acta Médica Colombiana 1984; 9:1-14.
  8. 8 Schlichtig R, Grogono AW, Severinghaus JW. "Human PaCO2 and standard base excess compensation for acid-base imbalance." Critical Care Medicine 1998; 26:1173-1179.
  9. 9 Paulev PE, and Zubieta-Calleja GR. "Essentials in the Diagnosis of Acid-Base Disorders and their High Altitude Application". J Physiol Pharmacol 2005; 56 Suppl 4:155-70.
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Acid-Base Tutorial
Alan W. Grogono
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