Proudfoot et al evaluated the prognostic significance of plasma paraquat levels over time following ingestion. They developed a predictive line which separated probable nonsurvivors (above the line) from probable survivors (below the line).
Time in Hours After Ingestion |
Plasma Levels in mg/L |
4 |
2.0 |
6 |
0.6 |
10 |
0.3 |
16 |
0.16 |
24 |
0.10 |
If this data is analyzed in JMP the following lines can be estimated:
plasma concentration along predictive line over time interval =
= (A * (hours since ingestion)^3)) + (B * (hours since ingestion)^2)) + (C * (hours since ingestion) + D
Interval |
(hour)^3 |
(hour)^2 |
(hour) |
constant D |
4 - 6 |
0 |
0.1041667 |
-1.741667 |
7.3 |
6 - 10 |
-0.000224 |
0.0123413 |
-0.228516 |
1.575238 |
10 - 24 |
0 |
0.001131 |
-0.052738 |
0.7142857 |
Interpretation:
• A patient with a plasma level greater than the plasma concentration on the line is at risk for death.
• A patient with a plasma level less than the plasma concentration on the line will probably survive.
• A person precisely on the line would be indeterminate.
Limitations:
• The line was described in 1979. Survival is probably better today due to better critical care management. However, it can help separate patients into low and high risk groups.
Specialty: Toxicology, Emergency Medicine, Critical Care
ICD-10: ,