Critical Care Patients and Arterial CO2

- Updated on December 22, 2021

Critical Care Patients and Arterial CO2 1By Dr. Artour Rakhimov, Alternative Health Educator and Author

Critical Care Patients and Arterial CO2 2It was shown above that, in cases of cardiac arrest, carbon dioxide concentration is a reliable predictor of human survival. Meanwhile, critical care professionals often use the most sophisticated and advanced devices to measure different physiological parameters. Analysis of arterial blood usually includes investigation of blood gases (blood concentrations of bicarbonates, total CO2, oxygenation, etc.) of critically ill patients.

All 29 patients with severe liver damage (in most cases due to metastatic cancer or cirrhosis of the liver) had low CO2, while for 25 patients “it was also clinically evident that respiratory exchange was increased markedly” (p.762, Wanamee et al, 1956). Thus, hyperventilation was visually observed by the authors of this publication, “Respiratory alkalosis in hepatic coma“. They also found that heavy over-breathing led to severe electrolyte abnormalities. These abnormalities included decreased sodium ions and increased chloride ions in the blood. Abnormally high lactic and pyruvic acid concentrations were other frequent effects.

Blood gases and respiratory patterns provided accurate information for survival prognosis in acute cerebrovascular accidents. When these parameters were normal, patients survived. Out of 11 hyperventilating patients with less than 35 mm Hg aCO2, only one survived (Rout et al, 1971).

The same conclusion (regarding aCO2 and survival prognosis) was made for head injuries (Huang et al, 1963; Vapalanti & Trouph, 1971).

Critical Care Patients and Arterial CO2 3Summarizing the results of these works and their connection with brain dysfunction, Dr. Plum wrote, “The combination of hyperpnoea [increased breathing] with an elevated pH, and a subnormal or moderately low oxygen tension occurs in many serious illnesses that entirely spare the brain. These include the alveolar-capillary block of diffuse pulmonary carcinomatosis; heart failure; advanced cirrhosis, with or without hepatic coma; acute pulmonary

infarction; and many others, including the cryptic pulmonary congestion that accompanies most serious disease in the obtunded and elderly” (Plum, 1972). Interestingly, all the above-mentioned effects (low carbon dioxide concentration, elevated pH, and hypoxia) quoted by Dr. Plum are caused by heavy breathing.

Hence, one can conclude that over-breathing is a normal feature of these severe diseases.

When suffering various serious health problems (heart disease, diabetes, cancer, AIDS, etc.) the patient’s life is usually threatened, not by the main health problem, but by complications and infections, such as in the case of bacteremic shock. Analyzing a group of patients initially diagnosed with arteriosclerotic heart disease, cerebrovascular insufficiency, diabetes, arthritis, several forms of cancer, fatty liver, and alcoholism, one study showed that complications due to pathogenic microorganisms in the blood caused 46 deaths in 50 patients (Winslow et al., 1973). Pneumonia and urinary tract infections were the foci of pathogenic microorganisms. Now we may ask the following: what was observed with their breathing when not only a part of the organism but even the blood was polluted with pathogens? All 50 patients, according to a table accompanying this article, had very disturbed blood gases corresponding to severe over-breathing.

Dr. Simmons and his colleagues wrote an article “Hyperventilation and respiratory alkalosis as signs of gram-negative bacteremia” (bacteremia being the presence of bacteria in the blood). This extract is from the beginning of their abstract:

Visible hyperventilation was observed clinically in patients with Gram-negative bacteremia. Eleven patients with Gram-negative infections and either proved or probable bacteremias were therefore studied to see if hyperventilation might be a common response to such bacteremia. In every case, there was laboratory evidence of hyperventilation, and in 8 cases the hyperventilation was visible to the observer. Since only patients were studied who had no other cause for increased ventilation, this appears to be a primary response to the bacteremia…” (abstract, Simmons et al, 1960).

Another group of US medical professionals found that the degree of over-breathing has a strong correlation with overall mortality (Mazarra et al, 1974). Heavier breathing indicated smaller chances of survival. Here is what they wrote in their scientific abstract:

Respiratory alkalosis [blood alkalization is the normal physiological result of over-breathing] was the most common acid-base disturbance observed in a computer analysis of 8,607 consecutive arterial blood gas studies collected over an 18 month period in a large intensive care unit.

Through a retrospective review of the randomly selected hospital records of 114 patients, we defined four groups based upon arterial carbon dioxide tension (PaCO2) and mode of ventilation. Group I, with a PaCO2 of 15 mm Hg or less, consisted of 25 patients with an overall mortality of 88 percent. Group II, with a PaCO2 of 20 to 25 mm Hg, consisted of 35 patients with a mortality of 77 percent. Group III, with a PaCO2 of 25 to 30 mm Hg, consisted of 33 patients with a mortality of 73 percent, and Group IV, with a PaCO2 of 35 to 45 mm Hg, consisted of 21 patients with a mortality of 29 percent (p<0.001). Shock and sepsis were most common in group I patients. These findings suggest that extreme hypocapnia [low level of carbon dioxide] in the critically ill patient has serious prognostic implications and is indicative of the severity of the underlying disease” (Mazarra et al, 1974). This article indicated that the names of the most common diseases to occur in all 4 groups of people were a cerebrovascular disease, hepatic coma, bronchopneumonia, and arteriosclerotic heart disease. Finally, let us look at the conclusion drawn by a group of US researchers who recently wrote an article with the title “Can cardiac sonography and capnography be used independently and in combination to predict resuscitation outcomes?” (Salen et al, 2001).

“CONCLUSIONS: Both the sonographic detection of cardiac activity and ETCO(2) levels higher than 16 torrs were significantly associated with survival from ED resuscitation; however, logistic regression analysis demonstrated that prediction of survival using capnography was not enhanced by the addition of cardiac sonography” (Salen et al, 2001).

In other words, they found, probably to their surprise, that monitoring of the heart, as in addition to the monitoring of breathing, does not provide any further information about chances of survival. A review of these professional studies indicates that critically ill patients usually have very low carbon dioxide levels due to visible hyperventilation. The labored breathing of such patients probably corresponds to minute ventilation of 20-25 l/min or more.

The analysis of Western medical literature suggests that many critically ill patients die in conditions of heavy and deep breathing.

Deep breathing, as we showed above, reduces oxygenation of the body. Are there any simple tests that reflect our ventilation and oxygenation? “Oxygen content in the organism can be found using a simple method: after exhalation, observe, how long time the person can have no breathing without stress” (Buteyko, 1977).


Mazarra JT, Ayres SM, Grace WJ, Extreme hypocapnia in the critically ill patient, Amer J Med Apr 1974, 56: p. 450-456.

Plum F, Hyperpnea, hyperventilation and brain dysfunction, Annals of Intern Med 1972, 76: p. 328.

Salen P, O’Connor R, Sierzenski P, Passarello B, Pancu D, Melanson S, Arcona S, Reed J, Heller M, Can cardiac sonography and capnography be used independently and in combination to predict resuscitation outcomes? Acad Emerg Med 2001 Jun; 8(6): p. 610-615.

Simmons DH, Nicoloff J, Guze LB, Hyperventilation and respiratory alkalosis as signs of gram-negative bacteremia, J Amer Med Assoc 1960, 174: p. 2196-2199.

Vapalanti M & Troup H, Prognosis for patients with severe brain injuries, Br Med J 1971, 3: p. 404-407.

Wanamee P, Poppel JW, Glicksman AS, Randall HT, Roberts KE, Respiratory alkalosis in hepatic coma, Arch Intern Med 1956, 97: p. 762-767.

Extract from Dr. Artour Rakhimov's Amazon book "Normal Breathing: The Key to Vital Health", also available in PDF.