BONENT CHN common mistakes
BONENT CHN · Understand the traps and how to avoid them.
Computes the ultrafiltration goal as pre-treatment weight minus target weight and stops there, ignoring saline given during the treatment, prime/rinseback volume, and any fluid or medication infused on the machine.
Items give two weights and a treatment time, so the obvious subtraction feels like the whole answer; the difference between net fluid loss and total fluid to be removed is rarely drilled in practice, where the machine's hourly rate does the bookkeeping.
What to do instead
Before answering, write out a UF ledger: total volume to remove = (pre-weight minus target weight) plus prime/rinseback plus saline/infusions given; then check that the hourly removal rate equals total volume divided by treatment time. State both numbers in your scratch work so the item cannot pull you into the shortcut.
On 'first action' or 'priority' items, selects an intervention (increase ultrafiltration, give a fluid bolus, call the nephrologist) instead of an assessment or monitoring step.
Interventions are the most memorable content studied, so they surface first under time pressure; the stem reads like a task list and candidates answer 'what needs to happen' rather than 'what happens first.'
What to do instead
Apply a fixed screen to every acute-change item: airway/breathing/circulation, then assess or verify before treating, then treat, then escalate. If an option is a focused assessment or a check of a machine parameter that would change the treatment, rank it above any therapy option unless the stem describes an immediately life-threatening finding.
Answers anemia-of-CKD items by naming iron deficiency as the primary mechanism, or by selecting a transfusion or iron product for a stable patient without first linking the anemia to reduced erythropoietin production.
Iron studies and ESA dosing are the day-to-day anemia work on the unit, so iron is the most accessible association; the underlying endocrine failure of the kidney is learned once and then overshadowed by routine labs.
What to do instead
Build a one-line mechanism chain and rehearse it: failing kidney parenchyma leads to decreased erythropoietin, which leads to understimulated marrow and normocytic normochromic anemia. Then treat iron deficiency as a common separate contributor that must be ruled out with iron studies, not as the cause of the anemia of CKD.
Answers acid-base items by pattern-matching a memorized compensation mnemonic against the numbers before identifying which process is primary.
Mnemonics are high-yield and easy to recall, so they get applied first; compensation rules only work after the primary disorder is named, and candidates skip that step.
What to do instead
Use a fixed three-step routine on every blood gas: (1) name the pH direction to establish acidemia or alkalemia, (2) identify which of carbon dioxide or bicarbonate moved in the direction that explains the pH, (3) only then judge whether the other value compensates appropriately or reveals a second process. Do the three steps explicitly in scratch work.
Treats arterial and venous pressure alarms as interchangeable 'pressure problems,' or attributes a venous pressure alarm to the access rather than to the return side of the circuit.
Both values appear side by side on the same screen with similar-looking alarm behavior, and both can stop the blood pump, so the segments they represent blur together.
What to do instead
Localize every pressure item by segment: pre-pump arterial pressure reflects how easily blood is drawn from the access (needle position, access flow, kinks on the arterial line), while post-dialyzer venous pressure reflects resistance to returning blood (needle placement, infiltration, clotting or kinks on the venous line, venous chamber). Ask yourself which side of the pump the sensor sits on before choosing.
Uses blood flow rate, dialysate flow rate, and transmembrane pressure as if they were interchangeable settings, or selects a TMP change when the item is asking about clearance.
All three are machine settings set or displayed at the same station and all are described in terms of flow or pressure, so candidates match on the words in the stem rather than on what the number physically does.
What to do instead
Anchor each term to one job and one unit: blood flow rate is the volume of blood per time past the membrane and, with dialysate flow rate, drives diffusive clearance; dialysate flow rate is the volume of dialysate per time on the other side of the membrane; transmembrane pressure is the pressure gradient across the membrane and drives convective water removal. If the stem is about clearance, the answer involves flows; if it is about fluid removal, it involves the pressure gradient.
Assumes the water softener removes chlorine or chloramine, or that the carbon tanks remove hardness, when asked to identify which component protects against a given contaminant.
The pre-treatment components sit in a row and are all described as tanks that 'clean' the water, so their individual jobs collapse into a single generic function.
What to do instead
Memorize the chain in order with a single purpose each: softener removes hardness (calcium and magnesium) by ion exchange; carbon removes chlorine and chloramine and certain organics; reverse osmosis removes dissolved solutes, bacteria, and endotoxin; a deionizer, where present, removes residual ions. Answer contaminant items by walking the chain in order and naming the first component whose stated job matches the contaminant.
Judges dialysate safety from the conductivity reading alone, or treats conductivity and pH as two ways of measuring the same thing.
Both are meter readouts displayed and documented together, and both are checked at the start of treatment, so they merge into a single 'dialysate is fine' check.
What to do instead
Keep them distinct in your notes: conductivity reflects total ionic concentration of the dialysate, while pH reflects acidity, and neither substitutes for the other. Also remember that neither measurement detects chlorine or chloramine, which require their own specific testing of the water, not the dialysate.
Omits hand hygiene because gloves were worn for the task, or changes gloves between patients without performing hand hygiene.
Gloves feel like a barrier that replaces handwashing, and glove changes are visible while hand hygiene is quick and easy to skip in a task-focused sequence.
What to do instead
Treat gloves as task-specific PPE, not as hand hygiene: perform hand hygiene immediately before donning and immediately after removing gloves, and never let a glove change stand in for it. On items describing a sequence, count hand hygiene steps as mandatory rather than optional when ranking the actions.
Focuses catheter care answers on the exit site and dressing while neglecting disinfection of the catheter hub, or selects a sequence in which the hub is touched after disinfection.
The exit site is what is visible and taught with dressing changes, while hub contamination is invisible and its contribution to bloodstream infection is not intuitive.
What to do instead
For every catheter item, build the sequence explicitly: hand hygiene, gloves, assess exit site, disinfect the hub with friction and allow it to dry, do not touch the disinfected hub, then access. If an option includes touching the hub or connecting to a hub that has not been disinfected and allowed to dry, eliminate it.