CCHT - Certified Clinical Hemodialysis Technician Water Treatment and Quality 1

Question 1

What is the primary role of carbon tanks in the dialysis water treatment system?

Accepted Answer

Adsorb chlorine and chloramines before water reaches the RO membrane

Answer

Carbon tanks use activated carbon to adsorb chlorine and chloramines from the feed water. These chemicals must be removed before the water contacts the reverse osmosis membrane, as they can degrade the membrane and, if they reach the patient, cause hemolytic anemia.

Question 2

According to AAMI standards, what is the maximum allowable endotoxin level in water used for standard hemodialysis?

Accepted Answer

2 EU/mL

Answer

AAMI standards set the maximum endotoxin level at 2 EU/mL for standard dialysis water, with an action level of 1 EU/mL. Exceeding these limits puts patients at risk for pyrogenic (fever-producing) reactions during treatment.

Question 3

What is the primary mechanism by which a reverse osmosis (RO) system purifies dialysis water?

Accepted Answer

Forcing water through a semi-permeable membrane under pressure, rejecting 90–99% of dissolved solutes

Answer

The RO system uses hydraulic pressure to push water through a semi-permeable membrane. The membrane's pore size is small enough to reject most dissolved ions, organics, bacteria, and endotoxins, producing highly purified product water while concentrating contaminants in a reject stream.

Question 4

Which reagent is used in the standard colorimetric test to check for free chlorine residual in dialysis water?

Accepted Answer

DPD (N,N-diethyl-p-phenylenediamine)

Answer

DPD reacts with free chlorine to produce a pink-to-red color, allowing a rapid and accurate colorimetric measurement. It is the AAMI-recommended method for verifying that carbon tank effluent meets the safe chlorine limit (≤0.1 mg/L) before dialysis begins.

Question 5

At minimum, how frequently should dialysis water be tested for bacteriological contamination according to AAMI guidelines?

Accepted Answer

Monthly

Answer

AAMI guidelines require bacteriological testing of dialysis water at least once per month. Monthly monitoring ensures that any microbial growth in the distribution loop or storage tank is detected before bacterial counts rise to levels that could cause patient infections or pyrogenic reactions.

CCHT - Certified Clinical Hemodialysis Technician Practice Test

CCHT - Certified Clinical Hemodialysis Technician Practice Test

CCHT - Certified Clinical Hemodialysis Technician Water Treatment and Quality 1