Fig. 1.

Gamblegrams of different acid–base conditions. A Normal conditions. This Gamblegram, i.e. the graph summarizing the electrical charges and the concept of electrical neutrality, represents a normal situation, with standard concentrations of electrolytes and normal acid–base parameters (HCO₃⁻ 24 mmol/L, PCO₂ 40 mmHg and pH of 7.40), leading to a SBE of 0 mmol/L. B Lactatemia. In this situation, lactate concentration is increased by 6 mmol/L and pH is 7.31. Other electrolytes and PCO₂ have normal values. HCO₃⁻ concentration is decreased to 20 mmol/L and BE is − 6 mmol/L. This is an example of isolated metabolic acidosis. C Hypochloremia. In this situation, chloride concentration is decreased by 5 mmol/L and pH is 7.47. Other electrolytes and PCO₂ have normal values. HCO₃⁻ concentration is increased to 29 mmol/L and BE is + 5 mmol/L. This is an example of isolated metabolic alkalosis, which can frequently be observed in case of persistent vomiting or after administration of loop diuretics. D Lactatemia and sodium bicarbonate (NaHCO₃). In this situation, lactate concentration is increased by 10 mmol/L and sodium concentration is increased by 10 mmol/L due to the administration of NaHCO₃. Other electrolytes and PCO₂ have normal values. As the increase in cations is equal to the increase in anions, no other change in electrolytes is required to fulfill the electroneutrality principle, i.e. HCO₃⁻ concentration is unaffected (24 mmol/L) and pH is 7.40. Therefore, two acid–base disorders co-exist and cancel each other out. Consequently, the calculated SBE is 0 mmol/L. Of note, the columns are higher than normal, underlining the fact that sodium-bicarbonate administration causes an increase in osmolarity. E Hyponatremia, hypochloremia and ketoacids. In this situation, sodium and chloride concentrations are reduced by 20 and 30 mmol/L, respectively. At the same time, 10 mmol/L of ketoacids are present. Also in this case, variations in strong cations and anions cancel out each other and, assuming a normal PCO₂ of 40 mmHg, normal values of pH and HCO₃⁻ are expected, leading to a normal SBE of 0 mmol/L. This acid–base derangement can be observed in infants with hypertrophic pyloric stenosis, where electrolyte losses due to persistent vomiting can coexist with hypovolemia and starvation ketoacidosis. HCO₃⁻, bicarbonate; A⁻, dissociated non-carbonic weak acids; Lac⁻, lactate; Ket⁻, ketoacids