Comparison of non-invasive to invasive oxygenation ratios for diagnosing acute respiratory distress syndrome following coronary artery bypass graft surgery: a prospective derivation-validation cohort study

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Farshid R.,Vahedian-Azimi,Amir,Farzanegan,Behrooz,Goharani Bashar (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Objective: To determine if non-invasive oxygenation indices, namely peripheral capillary oxygen saturation (SpO2)/fraction of inspired oxygen (FiO2) and partial pressure of alveolar oxygen (PAO2)/FiO2 may be used as effectivesurrogates for the partial pressure of arterial oxygen (PaO2)/FiO2. Also, to determine the SpO2/FiO2 and PAO2/FiO2values that correspond to PaO2/FiO2 thresholds for identifying acute respiratory distress syndrome (ARDS) inpatients following coronary artery bypass graft (CABG) surgery.Methods: A prospective derivation-validation cohort study in the Open-Heart ICU of an academic teaching hospital.Recorded variables included patient demographics, ventilator settings, chest radiograph results, and SPO2, PaO2,PAO2, SaO2, and FiO2. Linear regression modeling was used to quantify the relationship between indices. Receiveroperating characteristic (ROC) curves were used to determine the sensitivity and specificity of the threshold values.Results: One-hundred seventy-five patients were enrolled in the derivation cohort, and 358 in the validationcohort. The SPO2/FiO2 and PAO2/FiO2 ratios could be predicted well from PaO2/FiO2, described by the linearregression models SPO2/FiO2 = 71.149 + 0.8PF and PAO2/FiO2 = 38.098 + 2.312PF, respectively. According to the linearregression equation, a PaO2/FiO2 ratio of 300 equaled an SPO2/FiO2 ratio of 311 (R2 0.857, F 1035.742, < 0.0001) anda PAO2/FiO2 ratio of 732 (R2 0.576, F 234.887, < 0.0001). The SPO2/FiO2 threshold of 311 had 90% sensitivity, 80%specificity, LR+ 4.50, LR- 0.13, PPV 98, and NPV 42.1 for the diagnosis of mild ARDS. The PAO2/FiO2 threshold of 732had 86% sensitivity, 90% specificity, LR+ 8.45, LR- 0.16, PPV 98.9, and NPV 36 for the diagnosis of mild ARDS. SPO2/FiO2 had excellent discrimination ability for mild ARDS (AUC ± SE = 0.92 ± 0.017; 95% CI 0.889 to 0.947) as did PAO2/FiO2 (AUC ± SE = 0.915 ± 0.018; 95% CI 0.881 to0.942). Conclusions: PaO2 and SaO2 correlated in the diagnosis of ARDS, with a PaO2/FiO2 of 300 correlating to an SPO2/FiO2 of 311 (Sensitivity 90%, Specificity 80%). The SPO2/ FiO2 ratio may allow for early real-time rapid identification ofARDS, while decreasing the cost, phlebotomy, blood loss, pain, skin breaks, and vascular punctures associated withserial arterial blood gas measurements.

Additional Information

Publication

Other

Language: English

Date: 2018

Keywords

Coronary artery bypass graft surgery, Acute respiratory distress syndrome, Oxygenation indices, Ratio of arterial oxygen partial pressure to fractional inspired oxygen, Ratio of peripheral capillary oxygen saturation to fractional inspired oxygen, Ratio o

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