title: Decrease in spectral entropy by low tidal volume ventilation-associated severe hypercapnia: a case report.
abstract: Severe hypercapnia can be predicted by a decrease in cerebral electrical activity. The authors describe a sudden decrease in spectral entropy due to severe hypercapnia-induced respiratory acidosis in a patient with chronic pulmonary obstructive disease during lung resection. After two and a half hours of low tidal volume ventilation in the lateral position, the state entropy suddenly dropped from 45 to 7, without any changes in the effect-site concentration of propofol, end-tidal carbon dioxide (CO2) tension, oxygen saturation, or arterial pressure. However, arterial blood gas analysis showed severe respiratory acidosis (pH 7.01, PaCO2115 mmHg and PaO2246 mmHg with FIO2of 0.5). Immediate hyperventilation improved the state entropy and acid-base balance. Electroencephalography-based spectral entropy can detect severe hypercapnia in chronic pulmonary obstructive disease patients with a large arterial to end-tidal CO2difference due to prolonged hypoventilation during thoracic surgery.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Yeungnam University School of Medicine, Daegu, Korea.
authors.forename: Junggun
authors.identifier: 0000-0002-1105-4763
authors.initials: J
authors.lastname: Ann
authors.affiliation: Department of Anesthesiology and Pain Medicine, Yeungnam University School of Medicine, Daegu, Korea.
authors.forename: Sung Mee
authors.identifier: 0000-0001-5602-9011
authors.initials: SM
authors.lastname: Jung
authors.affiliation: Department of Anesthesiology and Pain Medicine, Yeungnam University School of Medicine, Daegu, Korea.
authors.forename: Sang-Jin
authors.identifier: 0000-0002-4838-2664
authors.initials: SJ
authors.lastname: Park
keywords: Electroencephalography; Entropy; Hypercapnia; Hypoventilation