Dialysis Patient in PEA: Access and the Potassium Problem
A 63-year-old man with end-stage kidney disease on thrice-weekly hemodialysis missed his last two sessions. EMS finds him unresponsive and pale with slow agonal gasps, no palpable pulse, and a monitor showing a wide-complex PEA at 28/min. His chart includes an ECG from two weeks ago with peaked T waves and a QRS of 168 ms. Two peripheral IV attempts by an experienced paramedic have failed, one having infiltrated; 90 seconds have passed since the first attempt. The team carries a drill-type intraosseous device, and defibrillation pads are already applied. The nearest hospital is 12 minutes away; the closest dialysis-capable ED is 20 minutes away.
1. Vascular access decision: continue with peripheral IV attempts or place an IO? Which site, and why does site choice matter?
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Place an IO now. In cardiac arrest, peripheral access should not consume more than about 90 seconds of the resuscitation; two failed attempts plus an infiltrated line is the trigger to move on. Compressions should not be interrupted further for access.
Site choice matters for drug delivery speed. The proximal humerus is generally preferred in arrest because it drains into the central circulation more rapidly, giving shorter circulation times to the heart and brain; the proximal tibia is the traditional alternative and is entirely acceptable. Avoid a site on the same side as a recent vascular access complication or over an infected area; avoid a fractured limb. Landmarks and confirmation (loss of resistance, aspiration of marrow, ability to flush without extravasation) still apply.
Practical point: with an IO, flush 10 mL of saline after each drug so the medication actually leaves the marrow cavity, and re-flush between agents that cannot be mixed.
2. Sequence the medications you would give, with doses, and state the rule for giving several drugs through one IO.
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Working diagnosis is a hyperkalemic arrest, so the specific therapy is as important as the standard algorithm:
- Epinephrine 1 mg IV/IO, repeated every 3–5 minutes. In a nonshockable rhythm (PEA/asystole) it is given as early as feasible.
- Calcium chloride 10% 1 g (10 mL) IV/IO - the membrane-stabilizing agent for hyperkalemia. (Calcium gluconate 10%, 30 mL, if chloride is unavailable.)
- Sodium bicarbonate 50 mEq (one 8.4% ampule) IV/IO - shifts potassium intracellularly; particularly reasonable here given renal failure with likely acidosis.
- Continue high-quality CPR with 2-minute rhythm checks; treat reversible causes (hypovolemia, hypoxia, acidosis, potassium, hypothermia, toxins, tamponade, tension pneumothorax, thrombosis).
Rule for a single IO line: give each drug as a bolus, then flush with at least 10 mL of saline before the next drug. Never assume a drug has reached the central circulation because it was pushed into the marrow.
Once ROSC occurs, the definitive treatment is urgent dialysis; the calcium effect is transient (minutes to tens of minutes), so the patient can re-arrest while awaiting it.
3. Explain the reasoning behind calcium in this arrest and the interaction risk with bicarbonate.
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Why calcium: hyperkalemia depolarizes the resting membrane potential toward threshold, producing wide QRS complexes, peaked T waves, sine-wave morphology, and eventually PEA or asystole. Calcium does not lower the potassium; it restores the threshold difference across the myocardial membrane, stabilizing the conduction system within minutes. It is the fastest-acting therapy when the rhythm is clearly hyperkalemic (dialysis patient, wide QRS, peaked T waves, missed sessions). Its effect wears off, which is why dialysis remains the definitive treatment.
Interaction risk: calcium salts and sodium bicarbonate precipitate as calcium carbonate when mixed. In a shared IO line this can occlude the needle and deliver neither drug. Therefore:
- Do not draw them into the same syringe or co-administer.
- Give one, then flush generously (≥10 mL saline) before giving the other, and flush again afterward.
- Watch for loss of IO flow after bicarbonate; if resistance appears, the line may be precipitating and a second site may be needed.
Avoid calcium in suspected digoxin toxicity, where it is traditionally considered harmful.