In the paper Kim et al [1] there are some discrepancies with the literature.

1. In the first paragraph, the authors write that according to their reference 4 (Luft 2001), “there is no definite therapy for lactic acidosis”. However, Luft writes very clearly on his page S17 “The measures required are neutralisation of the excess hydrogen ions with NaHCO₃”. This emphasizes also the importance of acidosis (= low pH = high concentration of hydrogen ions H⁺) in the pathophysiology of lactic acidosis. Indirectly is this confirmed also by their reference 11 (Rachoin et al 2010). Rachoin et al write on their page E2 “Available data indicate that lactate itself is not harmful”. The importance of low blood pH in the detrimental effects of acidosis in human patients is explained by Nyenwe et al [2]: the glycolytic enzyme phosphofructokinase is pH-dependent, as its activity is decreasing with decreasing pH and, thus, glucose utilisation in brain cells is impaired. The consequence is decreasing level of consciousness including coma. And coma is also the most dangerous effect of severe lactic acidosis (e g, [3]; this paper confirms also the utility of sodium bicarbonate in the treatment of lactic acidosis- recommended by Luft - reference 4 of Kim et al). In the paper of Kim et al [1] are comatose patients with lactic acidosis not mentioned - thus, the degree of their lactic acidosis was not severe, and, therefore, the indication for sodium bicarbonate therapy is doubtful.
2. In the second paragraph, the authors write “Metabolic acidosis with lactic acidosis or without lactic acidosis may depress cardiac contractility ...” This has been observed only in anesthesized experimental animals and isolated organs; in human patients, very low blood pH (around 6.8 - 6.9) has no adverse cardiovascular effects (e g.[4]).

Dr. Viktor Rosival, PhD
SYNLAB Department of Laboratory Menicine, Dérers Hospital
Limbova 5, SK-833 05 Bratislava,
Slovakia, Europe.

References
1. Kim HJ, San YK, An WS (2013) Effect of sodium bicarbonate administration on mortality in patients with lactic acidosis: a retrospective analysis. PLOS ONE 8: e65283.
2. Nyenwe EA, Khan AE, Razavi LN, Wan JY, Kitabchi AE (2010) Acidosis: The Prime Determinant of Depressed Sensorium in Diabetic Ketoacidosis. Diab Care 33: 1831-1839.
3. Ahmad S, Beckett M (2002) Recovery from ph 6.38: lactic acidosis complicated by hypothermia. Emerg Med J 19: 169-171.
4. Maury E, Vassal T, Offenstadt G (1999) Cardiac Contractility during Severe Ketoacidosis. N Engl J Med 341: 1938.