Rationale
Blood gas analysis is often used to assess acid–base, ventilation, and oxygenation status in critically ill patients. Although arterial blood gas (ABG) analysis remains the gold standard, venous blood gas (VBG) analysis has been shown to correlate with ABG analysis and has been proposed as a safer less invasive alternative to ABG analysis.
Objective
The purpose of this study was to evaluate the correlation of VBG analysis plus pulse oximetry (SpO2) with ABG analysis.
Methods
We performed a prospective cohort study of patients in the emergency department (ED) and intensive care unit (ICU) at a single academic tertiary referral center. Patients were eligible for enrollment if the treating physician ordered an ABG. Statistical analysis of VBG, SpO2, and ABG data was done using paired t test, Pearson χ2, and Pearson correlation.
Main Results
There were 156 patients enrolled, and 129 patients completed the study. Of the patients completing the study, 53 (41.1%) were in the ED, 41 (31.8%) were in the medical ICU, and 35 (27.1%) were in the surgical ICU. The mean difference for pH between VBG and ABG was 0.03 (95% confidence interval: 0.03–0.04) with a Pearson correlation of 0.94. The mean difference for pCO2 between VBG and ABG was 4.8 mm Hg (95% confidence interval: 3.7–6.0 mm Hg) with a Pearson correlation of 0.93. The SpO2 correlated well with PaO2 (the partial pressure of oxygen in arterial blood) as predicted by the standard oxygen–hemoglobin dissociation curve.
Conclusion
In this population of undifferentiated critically ill patients, pH and pCO2 on VBG analysis correlated with pH and pCO2 on ABG analysis. The SpO2 correlated well with pO2 on ABG analysis. The combination of VBG analysis plus SpO2 provided accurate information on acid–base, ventilation, and oxygenation status for undifferentiated critically ill patients in the ED and ICU.
Introduction:Several factors influence the final placement of a medical student candidate on an emergency medicine (EM) residency program’s rank order list, including EM grade, standardized letter of recommendation, medical school class rank, and US Medical License Examination (USMLE) scores. We sought to determine the correlation of these parameters with a candidate’s final rank on a residency program’s rank order list.Methods:We used a retrospective cohort design to examine 129 candidate packets from an EM residency program. Class ranks were assessed according to the instructions provided by the students’ medical schools. EM grades were scored from 1 (honors) to 5 (fail). Global assessments noted on the standardized letter of recommendation (SLOR) were scored from 1 (outstanding) to 4 (good). USMLE scores were reported as the candidate’s 3-digit scores. Spearman’s rank correlation coefficient was used to analyze data.Results:Electronic Residency Application Service packets for 127/129 (98.4%) candidates were examined. The following parameters correlated positively with a candidate’s final placement on the rank order list: EM grade, ρ = 0.379, P < 0.001; global assessment, ρ = 0.332, P < 0.001; and class rank, ρ = 0.234, P = 0.035. We found a negative correlation between final placement on the rank order list with both USMLE step 1 scores, ρ = −0.253, P=0.006; and USMLE step 2 scores, ρ = −0.348, P = 0.004.Conclusion:Higher scores on EM rotations, medical school class ranks, and SLOR global assessments correlated with higher placements on a rank order list, whereas candidates with higher USMLE scores had lower placements on a rank order list. However, none of the parameters examined correlated strongly with ultimate position of a candidate on the rank list, which underscores that other factors may influence a candidate’s final ranking.
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