Severe hypocalcemia and seizures after normalization of pCO2 in a patient with severe bronchopulmonary dysplasia and permissive hypercapnia

Abstract Objectives To describe the association between the rapid normalization of pCO2 after intubation in a patient with severe bronchopulmonary dysplasia managed with permissive hypercapnia, with the risk of developing hypocalcemia and seizures, and to make health care providers aware of this risk in similar cases. Case presentation An extreme premature infant, born at 25 weeks of gestational age (GA), developed a severe bronchopulmonary dysplasia (BPD) and, after several extubation failures could be managed with non-invasive ventilation and permissive hypercapnia, with capillary pCO2 of up to 80 mmHg and pH >7.20. At 46 postmenstrual age (PMA) he was intubated because of severe hypercapnia and compensating metabolic alkalosis. About 20 h after intubation, after normalization of pH and pCO2, he developed hypocalcemia and seizures, that remitted after iCa normalization. A comparison between arterial and capillary blood gases showed a significantly greater correlation between pH and iCa in arterial than in capillary samples. Conclusions Our findings emphasize the importance of avoiding the abrupt reduction of pCO2 and the close monitoring of acute metabolic changes after its correction in chronic patients with permissive hypercapnia, as well as the potential superiority of arterial samples over capillaries to improve the precision of this control.