title: Capnodynamic assessment of effective lung volume during cardiac output manipulations in a porcine model.
abstract: A capnodynamic calculation of effective pulmonary blood flow includes a lung volume factor (ELV) that has to be estimated to solve the mathematical equation. In previous studies ELV correlated to reference methods for functional residual capacity (FRC). The aim was to evaluate the stability of ELV during significant manipulations of cardiac output (CO) and assess the agreement for absolute values and trending capacity during PEEP changes at different lung conditions. Ten pigs were included. Alterations of alveolar carbon dioxide were induced by cyclic reoccurring inspiratory holds. The Sulphur hexafluoride technique for FRC measurements was used as reference. Cardiac output was altered by preload reduction and inotropic stimulation at PEEP 5 and 12 cmH2O both in normal lung conditions and after repeated lung lavages. ELV at baseline PEEP 5 was [mean (SD)], 810 (163) mL and decreased to 400 (42) mL after lavage. ELV was not significantly affected by CO alterations within the same PEEP level. In relation to FRC the overall bias (limits of agreement) was -35 (-271 to 201) mL, and percentage error 36 %. A small difference between ELV and FRC was seen at PEEP 5 cmH2O before lavage and at PEEP 12 cmH2O after lavage. ELV trending capability between PEEP steps, showed a concordance rate of 100 %. ELV was closely related to FRC and remained stable during significant changes in CO. The trending capability was excellent both before and after surfactant depletion.
authors.affiliation: Department of Anesthesiology, Surgical Services and Intensive Care Medicine, Karolinska University Hospital, 171 76, Solna, Stockholm, Sweden. caroline.hallsjo-sander@karolinska.se.|Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden. caroline.hallsjo-sander@karolinska.se.
authors.forename: Caroline
authors.identifier: http://orcid.org/0000-0002-6341-2630
authors.initials: C
authors.lastname: Hällsjö Sander
authors.affiliation: Paediatric Anesthesia and Intensive Care Astrid Lindgrens Children's Hospital, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Per-Arne
authors.initials: PA
authors.lastname: Lönnqvist
authors.affiliation: Maquet Critical Care AB, Solna, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Hallbäck
authors.affiliation: Hedenstierna Laboratory, Department of Surgical Sciences, Section of Anesthesiology and Critical Care, Uppsala University, Uppsala, Sweden.|CIBERES, CIBER de enfermedades respiratorias, Instituto Carlos III, Madrid, Spain.
authors.forename: Fernando Suarez
authors.initials: FS
authors.lastname: Sipmann
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.|Maquet Critical Care AB, Solna, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Wallin
authors.affiliation: Department of Anesthesiology, Surgical Services and Intensive Care Medicine, Karolinska University Hospital, 171 76, Solna, Stockholm, Sweden.|Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Oldner
authors.affiliation: Department of Anesthesiology, Surgical Services and Intensive Care Medicine, Karolinska University Hospital, 171 76, Solna, Stockholm, Sweden.|Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Björne
mesh_terms: D000758:Anesthesia; D000818:Animals; D002302:Cardiac Output / Q000502:physiology*; D005652:Functional Residual Capacity; D006439:Hemodynamics; D008168:Lung / Q000098:blood supply / Q000502:physiology* / Q000503:physiopathology; D055370:Lung Injury / Q000503:physiopathology; D008176:Lung Volume Measurements; D008962:Models, Theoretical; D011175:Positive-Pressure Respiration / Q000379:methods; D012016:Reference Values; D012039:Regional Blood Flow; D012129:Respiratory Function Tests; D013459:Sulfur Hexafluoride / Q000737:chemistry; D013501:Surface-Active Agents; D013552:Swine; D013990:Tidal Volume; D013997:Time Factors
chemical_list: D013501:Surface-Active Agents; D013459:Sulfur Hexafluoride
keywords: Capnodynamic method; Effective lung volume; Lung lavage; Monitoring; Porcine model