How to Troubleshoot CRRT TMP

Continuous Renal Replacement Therapy consists of low rate fluid removal for the critically ill and leads to steady state fluid equilibrium in hemodynamically unstable patients. In most cases, troubleshooting Transmembrane Pressure (TMP) can be accomplished without ceasing treatment. There are many brands of CRRT machines. The mechanics of these machines is relatively simple and fortunately, many aspects of troubleshooting the equipment is universal. It is easy to correct problems with TMP by vetting the circuit of the machine. By inspecting the all flow lines, checking the filter, and adjusting the pump and flows, problems can be identified and solved in a few easy steps. Typical dialysate and replacement fluid flow rates are between one and three liters per hour, and blood flow rate should be between 80 to 120 milliliters per minute. Effluent rate is equal to the fluid removal rate plus the replacement fluid rate and the dialysate rate. Slower rates are not effective for convective solute removal.

Instructions

Possible Causes of High TMP

• 1

  Check the green filtrate line. A clamp or kink in the filtrate line can cause a rapid rise in TMP.

• 2

  Determine whether the filter is clotting slowly. A clogged filter will cause a slow rise in TMP.

• 3

  Check the ratio between the blood and dialysate flows. If TMP was high at the beginning of treatment, the ratio between the flow of blood and dialysate is too high.

Troubleshooting

• 4

  Check for an obstruction, kink, clamp, or other blockage in the green filtrate line. Begin at the end of the line where it enters the machine. Check the connection and follow the filtrate line to where it enters the bag. Remove any obstruction in the line or connection to the bag.

• 5

  Determine whether increasing the pre-dilution rate and decreasing the post-dilution rate solves the problem. Flush the circuit using the rescue line to check for clotting in the filter. If recovery is observed after flushing, continue treatment. If the filter is too badly clogged, cease treatment to conserve blood and replace filter.

• 6

  Recommence treatment by decreasing the exchange rate or increasing the blood flow speed. Press the pump and balance keys. The machine should function properly.