title: New porcine test-model reveals remarkable differences between algorithms for spectrophotometrical haemoglobin saturation measurements with VLS.
abstract: The study created an 'ex vivo' model to test different algorithms for measurements of mucosal haemoglobin saturation with visible light spectrophotometry (VLS). The model allowed comparison between algorithms, but it also allowed comparison with co-oximetry using a 'gold standard' method. This has not been described before. Seven pigs were used. They were perfused with cold Haemaxel, and thus killed, chilled and becoming bloodless. The bronchial artery was perfused with cold blood with known saturation and spectrophotometrical measurements were made through a bronchoscope. Based on 42 spectrophotometrical measurements of porcine bronchial mucosa saturation with fully oxygenated blood and 21 with de-oxygenated blood, six algorithms were applied to the raw-spectra of the measurements and compared with co-oxymetry. The difference from co-oxymetry in the oxygenated and de-oxygenated state ranged from  -32.8 to  +29.9 percentage points and from  -5.0 to  +9.2 percentage points, respectively.
  
  
  
  the algorithms showed remarkable in-between differences when tested on raw-spectra from an 'ex vivo' model. All algorithms had bias, more marked at high oxygenation than low oxygenation. Three algorithms were dis-recommended.
authors.affiliation: Department of Cardio-thoracic Surgery RT, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark.
authors.forename: John
authors.initials: J
authors.lastname: Gade
authors.forename: Gorm
authors.initials: G
authors.lastname: Greisen
mesh_terms: D000465:Algorithms; D000818:Animals; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D008027:Light; D010092:Oximetry / Q000379:methods*; D013053:Spectrophotometry / Q000379:methods*; D013552:Swine
chemical_list: D006454:Hemoglobins