Hypercapnic Respiratory Failure in Case of Chiari 1.5 Malformation: Case Report and Review of the Literature.

Type 2 respiratory failure is defined as hypercapnia associated with hypoxia. Chiari 1.5 is known as herniation of the cerebellar tonsils along with brain stem and fourth ventricle. We report a 35-year-old male who presented with acute hypercapnic respiratory failure (Type 2), without any preexisting neurological or respiratory abnormality. Analysis of blood gases in emergency revealed a pH of 7.12, pCO2 of 132 mmHg, and arterial oxygen tension of 118 mm Hg. He was intubated and ventilated. Magnetic resonance imaging brain revealed herniation of the cerebellar tonsils along with brain stem and fourth ventricle. The patient underwent surgery and gradually weaned off. He was mobilized and discharged on day 6. Acute respiratory failure has not been reported with Chiari 1.5 malformation. The lesson to be learned from this case is that craniospinal pathology must be looked for in a patient with hypercapnic respiratory failure.