title: Multi frequency phase fluorimetry (MFPF) for oxygen partial pressure measurement: ex vivo validation by polarographic clark-type electrode.
abstract: BACKGROUND
  Measurement of partial pressure of oxygen (PO2) at high temporal resolution remains a technological challenge. This study introduces a novel PO2 sensing technology based on Multi-Frequency Phase Fluorimetry (MFPF). The aim was to validate MFPF against polarographic Clark-type electrode (CTE) PO2 measurements.
  
  
  RESULTS
  MFPF technology was first investigated in N = 8 anaesthetised pigs at FIO2 of 0.21, 0.4, 0.6, 0.8 and 1.0. At each FIO2 level, blood samples were withdrawn and PO2 was measured in vitro with MFPF using two FOXY-AL300 probes immediately followed by CTE measurement. Secondly, MFPF-PO2 readings were compared to CTE in an artificial circulatory setup (human packed red blood cells, haematocrit of 30%). The impacts of temperature (20, 30, 40°C) and blood flow (0.8, 1.6, 2.4, 3.2, 4.0 L min(-1)) on MFPF-PO2 measurements were assessed. MFPF response time in the gas- and blood-phase was determined. Porcine MFPF-PO2 ranged from 63 to 749 mmHg; the corresponding CTE samples from 43 to 712 mmHg. Linear regression: CTE = 15.59+1.18*MFPF (R(2) = 0.93; P<0.0001). Bland Altman analysis: meandiff 69.2 mmHg, rangediff -50.1/215.6 mmHg, 1.96-SD limits -56.3/194.8 mmHg. In artificial circulatory setup, MFPF-PO2 ranged from 20 to 567 mmHg and CTE samples from 11 to 575 mmHg. Linear regression: CTE = -8.73+1.05*MFPF (R(2) = 0.99; P<0.0001). Bland-Altman analysis: meandiff 6.6 mmHg, rangediff -9.7/20.5 mmHg, 1.96-SD limits -12.7/25.8 mmHg. Differences between MFPF and CTE-PO2 due to variations of temperature were less than 6 mmHg (range 0-140 mmHg) and less than 35 mmHg (range 140-750 mmHg); differences due to variations in blood flow were less than 15 mmHg (all P-values>0.05). MFPF response-time (monoexponential) was 1.48±0.26 s for the gas-phase and 1.51±0.20 s for the blood-phase.
  
  
  CONCLUSIONS
  MFPF-derived PO2 readings were reproducible and showed excellent correlation and good agreement with Clark-type electrode-based PO2 measurements. There was no relevant impact of temperature and blood flow upon MFPF-PO2 measurements. The response time of the MFPF FOXY-AL300 probe was adequate for real-time sensing in the blood phase.
authors.affiliation: Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria. stefan_boehme@web.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Boehme
authors.forename: Bastian
authors.initials: B
authors.lastname: Duenges
authors.forename: Klaus U
authors.initials: KU
authors.lastname: Klein
authors.forename: Volker
authors.initials: V
authors.lastname: Hartwich
authors.forename: Beate
authors.initials: B
authors.lastname: Mayr
authors.forename: Jolanda
authors.initials: J
authors.lastname: Consiglio
authors.forename: James E
authors.initials: JE
authors.lastname: Baumgardner
authors.forename: Klaus
authors.initials: K
authors.lastname: Markstaller
authors.forename: Reto
authors.initials: R
authors.lastname: Basciani
authors.forename: Andreas
authors.initials: A
authors.lastname: Vogt
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D005470:Fluorometry / Q000379:methods*; D008962:Models, Theoretical; D010100:Oxygen / Q000502:physiology*; D010313:Partial Pressure; D013552:Swine
chemical_list: D010100:Oxygen
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