The influence of delayed sample processing time on the PO₂ values in critically ill patients with sepsis-induced leukocytosis

 

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dc.contributor.advisor Myburgh, Adriaan en_ZA
dc.contributor.author Pretorius, Petrus Rohan en_ZA
dc.date.accessioned 2018-01-25T06:36:16Z
dc.date.available 2018-01-25T06:36:16Z
dc.date.issued 2017 en_ZA
dc.identifier.citation Pretorius, P. 2017. The influence of delayed sample processing time on the PO₂ values in critically ill patients with sepsis-induced leukocytosis. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/26939
dc.description.abstract Background: The ability to correctly measure the partial pressure of Oxygen is one of the fundamental test that influence clinical decision making in a septic ICU patient. The study examined the extent of error over time, from collection to processing, when measuring blood gas samples for PO₂, PCO₂, pH, in critically-ill patients with sepsis and metabolically active leucocytosis > 12 000/mm³ and compares it with a control, where immersing it in ice has stopped metabolism. Methods: Thirty septic ICU patients with confirmed leucocytosis > 12 000/mm³, who had routine arterial blood analysed was included in the study. Blood form the standard PICO50 radiometer arterial blood sampler (2ml) syringe was decanted into two 1ml Glass syringes that was pre-heparinised with 1ml Heparin 1000U - all excess Heparin removed. One syringe was cooled with ice slurry and tested as a control at 60 minutes The other syringe was used to repeatedly analyse the sample at 0,10, 30 and 60 minutes. The syringes were sealed with plastecine and a glass capillary tube was use to decant the sample just prior to analysis to fit the analyser. Samples were processed using an ABL 800 blood gas analyser. Results: The mean absolute difference in PO₂ at 10 minutes was -0.94 kPa (95% CI: -1.48 to -0.4 kPa), at 30 minutes -2.42 kPa (95% CI: -3.10 to -1.75 kPa) and at 60 minutes -4.44 kPa (95% CI: -5.54 to -3.34 kPa). The relative difference in pO₂ at 10 minutes was -4.98% (95% CI: -8.12 to -1.84%), at 30 minutes -13.79% (95% CI: -17.40 to -10.17%) and 60 minutes -25.46% (95% CI: -30.97 to -19.95%). The absolute difference in PO₂ at 60 minutes on Ice was - 0.31 kPa. Conclusion: Delayed blood gas analysis in Septic ICU patients with a raised WCC > 12 000/mm³, results in statistical and possible clinical significant abnormality in the pO₂, that progressively worsens with time. After 10 minutes there was a 5% change, at 30 minutes a 14% change and there was a 25% change from baseline PO₂ at 60 minutes. The magnitude of change with statistical mixed linear models shows the rate of decline to be of the magnitude of 1% per minute. So at 60 minutes, the ratio change is 0.7313859 (0.9948 to the power of 60).This deviation may alter clinical decision making. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Anaesthesia en_ZA
dc.title The influence of delayed sample processing time on the PO₂ values in critically ill patients with sepsis-induced leukocytosis en_ZA
dc.type Thesis / Dissertation en_ZA
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Health Sciences en_ZA
dc.publisher.department Department of Anaesthesia en_ZA
dc.type.qualificationlevel Masters en_ZA
dc.type.qualificationname MMed en_ZA
uct.type.filetype Text
uct.type.filetype Image


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