The braking phenomenon as a contributor to loop diuretic resistance after multiple doses

Patients may have a decreased response (ie, a decreased excretion of NaCl, shown in the y-axis) over time (shown in the x-axis) despite using the same dose of a loop diuretic. This is due to enhanced tubular sodium reabsorption in other parts of the nephron (other than the loop of Henle) and is called the "braking phenomenon." Each bar in the figure represents the sodium excreted during a 6-hour period. The horizontal dashed line represents the sodium intake. The black bars represent the 6-hour sodium excretion immediately after diuretic administration.