CO2 Gap Alone Is Not a Prognostic Marker for 28-Day Survival of Patients Undergoing a Transcatheter Aortic Valve Replacement

Figures

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  Figure 1. Patient inclusion chart. LV-EF = left ventricular ejection fraction. 1 A blood sample could not be taken at T5 for one patient, and for two patients, no blood samples could be taken from T3 to T5 because complications occurred in these patients during the TAVR that were unrelated to the blood sampling; 2 an arterial blood sample was taken instead of a venous blood sample.

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  Figure 2. Study protocol. TAVR = transcatheter aortic valve replacement; NT-proBNP = N-terminal pro B-type natriuretic peptide; T1 = after central venous catheter placement, T2 = before rapid pacing, T3 = after valve release, T4 = end of TAVR, T5 = up to 2 h after TAVR.

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  Figure 3. Temporal course of CO2 gap in (a) cardiac and non-cardiac patients and (b) survivors and non-survivors. Due to group size (n = 2), only mean is shown for non-survivors. CO2 gap = difference between central venous and arterial CO2 partial pressure; T1 = after placement of the central venous catheter, but before the start of the TAVR, T2 = immediately before rapid pacing, T3 = after aortic valve release, T4 = end of TAVR, T5 = up to 2 h after TAVR; * indicates that values differ significantly (p < 0.05) between two time points within survivors (blue).

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  Figure 4. ROC curve for predicting 28-day survival based on CO2 gap at time points T1 and T4. 1 Due to missing 28-day follow-up data for 2 out of 50 patients, the analysis was conducted on the remaining 48 patients (n = 48 out of 50 patients). CO2 gap = difference between central venous and arterial CO2 partial pressure (mmHg); T1 = after placement of the central venous catheter, but before the start of the TAVR, T4 = end of TAVR.

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  Figure 5. (a) CO2 gap vs. lactate levels in survivors at T1, T2, T3, T4 and T5. (b) CO2 gap vs. lactate in non-survivors at T1, T2, T3, T4 and T5. Due to the small group size of the non-survivor group (n = 2), only mean is shown. CO2 gap = difference between central venous and arterial CO2 partial pressure (mmHg); T1 = after placement of the central venous catheter, but before the start of the TAVR, T2 = immediately before rapid pacing, T3 = after aortic valve release, T4 = end of TAVR, T5 = up to 2 h after TAVR; * indicates that values differ significantly (p < 0.05) between two time points within lactate (blue) or CO2 gap (red).

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  Figure 6. (a) CO2 gap vs. lactate levels in the cardiac group at T1, T2, T3, T4 and T5. (b) CO2 gap vs. lactate levels in the non-cardiac group at T1, T2, T3, T4 and T5. CO2 gap = difference between central venous and arterial CO2 partial pressure (mmHg); T1 = after placement of the central venous catheter, but before the start of the TAVR, T2 = immediately before rapid pacing, T3 = after aortic valve release, T4 = end of TAVR, T5 = up to 2 h after TAVR; * indicates that values differ significantly (p < 0.05) between two time points within lactate (blue) or CO2 gap (red).

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  Figure 7. Temporal course of cv-art CO2 content in the (a) cardiac and non-cardiac group and (b) the survivor and non-survivor group. Cv-art CO2 content is measured with the Douglas equation. Due to the small group size of the non-survivor group (n = 2), only mean is shown. Cv-art CO2 content = difference between central venous and arterial CO2 content; T1 = after placement of the central venous catheter, but before the start of the TAVR, T2 = immediately before rapid pacing, T3 = after aortic valve release, T4 = end of TAVR, T5 = up to 2 h after TAVR; * indicates a significant difference (p < 0.05) between two time points (blue) or between two groups at a specific time point (black).

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  Figure 8. Ratio of CO2 gap to the arterial-to-venous O2 content difference in survivors and non-survivors at different time points. Due to the small group size of the non-survivor group (n = 2), only mean is shown. CO2 gap = difference between central venous and arterial CO2 partial pressure; T1 = after placement of the central venous catheter, but before the start of the TAVR, T2 = immediately before rapid pacing, T3 = after aortic valve release, T4 = end of TAVR, T5 = up to 2 h after TAVR; * indicates a significant difference (p < 0.05) between two time points (red) or between two groups at a specific time point (black).