Evaluation of Ventilatory Responses in Severe Acidemia in Diabetic Ketoacidosis

Abstract

Ventilatory response in patients with severe acidemia in diabetic ketoacidosis (DKA) was unresolved. Thus, 83 patients with uncomplicated DKA were studied for the relation between arterial blood pH, calculated bicarbonate concentration (HCO3) and carbon dioxide tension (PCO₂). The equation for the PCO₂/HCO₃ pair was: PCO₂ =1.58 × HCO₃ + 7.6 (SE 2.55, r = 0.95, p < 0.01); for the PCO₂/pH pair was: PC0₂ = 43.8 × pH-293 (SE 6.23, r = 0.66, p < 0.01). The correlation coefficient for the PCO₂/HCO₃ pair was significantly greater compared to the PCCVpH pair (p < 0.001). Multiple regression analysis showed that severe acidemia (pH ≤ 7.10) per se was independently associated with PCO₂ for the PCO₂/HCO₃ pair, but not for the PCO₂/pH pair. Thus, our patients were divided into 2 groups for the PCO₂/HCO₃ pair: group 1 with pH < 7.10 (n = 25) and group 2 with pH > 7.10 (n = 58). The equations were: group 1: PCO₂ = 3.18 × HCO3 + 2.88 (SE 1.72, r = 0.87, p < 0.01); group 2: PCO₂ = 1.65 × HCO₃ + 6.6 (SE 2.6, r = 0.95, p < 0.01). There was a significant difference between these 2 equations (p < 0.01). Mathematical simulations with 10 sets of 25 or 58 random pH/PCO₂ pairs (and calculated HCO₃) for ‘group 1’ and ‘group 2’ also showed similar results, albeit with less precision. Hence, ventilatory response in DKA varies between patients with severe acidemia and those with moderate acidemia by the PCO₂/HCO₃ pair, but not by the PCO₂/pH pair.

Continuous non-invasive end-tidal CO2 monitoring in pediatric inpatients with diabetic ketoacidosis

“…To determine the degree of agreement between measured EtCO 2 and vHCO 3 − , we sought to convert the EtCO 2 value into a comparable value. The following formula was published for use in patients with metabolic acidosis and is validated for use in predicting measured arterial HCO 3 − (mmol/L) from arterial pCO 2 (mmHg) (7–9):…”

End‐tidal Carbon Dioxide Predicts the Presence and Severity of Acidosis in Children with Diabetes

“…1 The normal physiologic compensation for metabolic acidosis is to increase minute ventilation, thereby decreasing arterial carbon dioxide tension (PaCO 2 ). Prior studies [2][3][4] using arterial blood gas analyses have shown that patients with metabolic acidosis demonstrate a predictable decrease in PaCO 2 such that Ϫ PaCO = 1.5 ϫ [HCO ] ϩ 8 2 3 The partial pressure of CO 2 at the end of an exhaled breath (ETCO 2 ) closely approximates arterial CO 2 (PaCO 2 ). 5 This relationship has been confirmed in normal children using nasal capnography.…”

Transcutaneous carbon dioxide monitoring during diabetic ketoacidosis in children and adolescents

“…Guh et al have suggested that at lower pH values, the hyperventilatory response is not complete (8). These authors studied 83 adult patients with uncomplicated DKA.…”