title: Liquid extracorporeal carbon dioxide removal: use of THAM (tris-hydroxymethyl aminomethane) coupled to hemofiltration to control hypercapnic acidosis in a porcine model of protective mechanical ventilation.
abstract: A promising approach to facilitate protective mechanical ventilation is the use of extracorporeal CO2 removal techniques. Several strategies based on membrane gas exchangers have been developed. However, these techniques are still poorly available. The goal of this study was to assess the efficacy and safety of THAM infusion coupled to hemofiltration for the management of hypercapnic acidosis. A severe respiratory acidosis was induced in seven anesthetized pigs. Five of them were treated with THAM 8-mmol·kg(-1)·h(-1) coupled to hemofiltration (THAM+HF group) at 100 mL·kg(-1)·h(-1). After 18-hours of treatment the THAM infusion was stopped but hemofiltration was kept on until 24-hours. The 2 other animals were treated with THAM but without hemofiltration. After 1-hour of treatment in THAM+HF, PaCO2 rapidly decreased from a median of 89.0 (IQR) (80.0, 98.0) to 71.3 (65.8, 82.0) mmHg (P<0.05), while pH increased from 7.12 (7.01, 7.15) to 7.29 (7.27, 7.30) (P<0.05). Thereafter PaCO2 remained stable between 60-70 mmHg, while pH increased above 7.4. After stopping THAM at 18 hours of treatment a profound rebound effect was observed with severe hypercapnic acidosis. The most important side effect we observed was hyperosmolality, which reached a maximum of 330 (328, 332) mOsm·kg H2O(-1) at T18. The animals treated only with THAM developed severe hypercapnia, despite the fact that pH returned to normal values, and died after 12 hours. Control-group had an uneven evolution until the end of the experiment. A combined treatment with THAM coupled to hemofiltration may be an effective treatment to control severe hypercapnic acidosis.
authors.affiliation: Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de ChileSantiago, Chile; Unidad de Paciente Crítico, Hospital Clínico Metropolitano La FloridaSantiago, Chile.
authors.forename: Pablo
authors.initials: P
authors.lastname: Tapia
authors.affiliation: Escuela de Medicina Veterinaria, Facultad de Ecologia y Recursos Naturales, Universidad Andres Bello Santiago, Chile.
authors.forename: Felipe
authors.initials: F
authors.lastname: Lillo
authors.affiliation: Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Dagoberto
authors.initials: D
authors.lastname: Soto
authors.affiliation: Departamento de Pediatría y Cirugía infantil, Campus Sur. Facultad de Medicina, Universidad de Chile Santiago, Chile.
authors.forename: Leslie
authors.initials: L
authors.lastname: Escobar
authors.affiliation: Departamento de Ciencias Biologicas, Facultad de Ciencias Biologicas & Facultad de Medicina, Universidad Andres BelloSantiago, Chile; Millennium Institute on Immunology and ImmunotherapySantiago, Chile.
authors.forename: Felipe
authors.initials: F
authors.lastname: Simon
authors.affiliation: Unidad de Hemodiálisis, Clínica Alemana Santiago, Chile.
authors.forename: Karina
authors.initials: K
authors.lastname: Hernández
authors.affiliation: Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Leyla
authors.initials: L
authors.lastname: Alegría
authors.affiliation: Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Bruhn
keywords: Acute respiratory distress syndrome; extracorporeal CO2 removal; hemofiltration; hypercapnia; tris hydroxymethyl aminomethane (THAM); ventilator induced lung injury