Table 5.
Results of a segmented linear regression analysis for modeling the relationship between 8 ECG variables and plasma potassium concentrations in calves of our study population
| Variable | n | Intercept | Slope 1 | Break point [K]1 | 95% CI for [K]1 | Slope 2 | Break point [K]2 | 95% CI for [K]2 |
|---|---|---|---|---|---|---|---|---|
| Ta wave amplitude | 117 | 0.02 | −0.02 | 5.7 | 5.0–6.4 | 0.03 | 8.4 | 6.7–10.1 |
| P wave amplitude | 117 | 0.01 | 0.04 | 6.5 | 6.1–6.9 | −0.16 | 8.2 | 7.5–8.9 |
| T to P amplitude ratio | 109 | 3.18 | 0 | 6.6 | 6.2–6.9 | 5.53 | – | – |
| S wave amplitude | 117 | −0.34 | −0.25 | 7.4 | 6.0–8.9 | 0.34 | – | – |
| QRS duration | 117 | 38.1 | 5.44 | 7.8 | 7.4–8.1 | 38.27 | – | – |
| J point amplitude | 117 | −0.05 | 0.01 | 7.9 | 7.5–8.3 | 0.12 | – | – |
| T to S amplitude ratio | 117 | 0.40 | 0 | 7.8 | 6.8‐8.7 | 0.16 | – | – |
| ST segment angle | 117 | −0.74 | 0.84 | 9.1 | 8.8–9.3 | 24.9 | – | – |
The slope in the 3rd model for P and Ta wave amplitude was 0.
Data from 13 hypokalemic calves were not included in the analysis.