Reduction of Risk Potential – RN Flashcards

Rapid-review flashcards for Reduction of Risk Potential at NCLEX-RN depth, emphasizing interpretation of results, anticipation of complications, and prioritization. Reference ranges are conventional teaching values; always confirm against the reporting laboratory's own range.

Laboratory Interpretation

Normal serum potassium range, and why it dominates cardiac safety

3.5 to 5.0 mEq/L. Both hypokalemia and hyperkalemia alter myocardial repolarization. Hypokalemia flattens T waves, depresses ST segments, and produces U waves; hyperkalemia peaks T waves and widens the QRS toward cardiac arrest.

Two absolute rules for intravenous potassium administration

Never give it by intravenous push or bolus and never intramuscularly. Always dilute and infuse by pump, generally no faster than 10 mEq per hour on a general unit, after confirming adequate urine output.

Why a client on digoxin with a "therapeutic" digoxin level can still be toxic

Hypokalemia, hypomagnesemia, hypercalcemia, renal impairment, and advanced age all increase myocardial sensitivity to digoxin, so toxicity can occur within the 0.5 to 2.0 ng/mL range.

How a low serum albumin changes the interpretation of a total calcium

Total calcium is largely albumin bound, so hypoalbuminemia falsely lowers the total value while the physiologically active ionized calcium may be normal. Confirm with an ionized calcium.

Hypokalemia that will not correct despite repletion suggests what

Untreated hypomagnesemia. Magnesium must be replaced for potassium to normalize.

Interpretation of pH 7.50, PaCO2 30 mm Hg, HCO3 24 mEq/L

Uncompensated respiratory alkalosis. The pH is alkalemic, the PaCO2 is low and explains it, and the bicarbonate has not yet shifted.

Interpretation of pH 7.30, PaCO2 38 mm Hg, HCO3 16 mEq/L

Uncompensated metabolic acidosis. Expect deep, rapid Kussmaul respirations as the body attempts respiratory compensation.

What a rise in serum creatinine from 0.9 to 1.8 mg/dL signifies

A doubling of creatinine represents a substantial drop in glomerular filtration, even though both numbers look small. Reassess nephrotoxic drugs, contrast exposure, and volume status.

A blood urea nitrogen to creatinine ratio well above 20 to 1 suggests what

A prerenal cause such as dehydration, hypovolemia, or gastrointestinal bleeding rather than intrinsic renal injury.

Which count, not the total white blood cell count, determines infection risk in neutropenia

The absolute neutrophil count. Below 500/mm3 is severe neutropenia, and fever in that setting is an emergency requiring immediate cultures and broad-spectrum antibiotics.

Platelet thresholds for procedural bleeding risk and spontaneous bleeding risk

Roughly below 50,000/mm3 for bleeding with trauma or procedures, and roughly below 20,000/mm3 for spontaneous bleeding.

Laboratory test, therapeutic range, and antidote for warfarin

International normalized ratio, usually 2.0 to 3.0 for atrial fibrillation and venous thromboembolism and 2.5 to 3.5 for many mechanical valves. Antidote is vitamin K (phytonadione).

Laboratory test, therapeutic range, and antidote for unfractionated heparin

Activated partial thromboplastin time, therapeutic at 1.5 to 2.5 times the control. Antidote is protamine sulfate.

Pattern that suggests heparin-induced thrombocytopenia and the required response

A marked platelet fall roughly five to ten days into heparin exposure, often with new thrombosis rather than bleeding. Stop all heparin including flushes and coated catheters, do not substitute low molecular weight heparin, and anticipate a non-heparin anticoagulant.

Why troponin is preferred over creatine kinase MB for a client presenting two days after chest pain

Troponin rises within a few hours of myocardial injury and remains elevated for several days, so it still detects a late presentation, while creatine kinase MB normalizes much sooner.

Signs of lithium toxicity and the conditions that precipitate it

Nausea, diarrhea, fine tremor, and drowsiness early; coarse tremor, ataxia, confusion, and seizures when severe. Precipitated by dehydration, sodium restriction, vomiting, diarrhea, heavy sweating, thiazide diuretics, and nonsteroidal anti-inflammatory drugs.

Vital Signs and Hemodynamics

Earliest reliable signs of hemorrhage and shock, before hypotension appears

Tachycardia, tachypnea, restlessness and anxiety from cerebral hypoperfusion, cool clammy skin, and a narrowing pulse pressure.

Cushing triad and what it indicates

Widening pulse pressure with rising systolic pressure, bradycardia, and irregular respirations. It is a late and ominous sign of markedly increased intracranial pressure and impending herniation.

Definition of orthostatic hypotension

A fall of at least 20 mm Hg systolic or 10 mm Hg diastolic within three minutes of moving to standing, usually with a compensatory rise in heart rate. It is a major fall risk.

Situations in which pulse oximetry is unreliable

Poor perfusion, hypothermia and vasoconstriction, motion, severe anemia, certain nail polish and artificial nails, and carbon monoxide poisoning. It also does not reflect ventilation, so it can be normal in significant hypercapnia.

Most likely cause of fever in the first 24 to 48 hours after surgery, versus later

Atelectasis early. Later fever suggests urinary tract infection, wound infection, pneumonia, or venous thromboembolism.

Procedures and Complications

Assessment finding after femoral cardiac catheterization that suggests retroperitoneal hemorrhage

New back or flank pain with hypotension and tachycardia, even when the groin dressing is dry, because blood tracks into the retroperitoneum.

Priority nursing actions if a client eviscerates

Stay with the client, position supine with knees slightly flexed, cover the viscera with sterile gauze moistened with sterile normal saline, do not attempt reinsertion, keep the client nothing by mouth, monitor for shock, and notify the surgeon.

Meaning of continuous bubbling in the water seal chamber of a chest drainage system

An air leak, either from the client or from a loose connection or dislodged dressing. Assess the system and site systematically; routine clamping and stripping are contraindicated.

Nursing response to a suspected air embolism during central line care

Clamp the line, place the client on the left side in Trendelenburg position, administer oxygen, and notify the provider.

Immediate steps when a transfusion reaction is suspected

Stop the transfusion, maintain the vein with normal saline through new tubing, assess vital signs, notify the provider and blood bank, and return the product and tubing per policy.

Distinguishing an acute hemolytic reaction from a febrile nonhemolytic reaction

Hemolytic reaction brings fever and chills plus low back or flank pain, hypotension, hemoglobinuria, and a sense of impending doom, and it is life threatening. Febrile nonhemolytic reaction is the most common reaction and presents with fever and chills without hemolysis.

Complication to anticipate after endoscopic retrograde cholangiopancreatography

Post-procedure pancreatitis, signaled by severe epigastric pain radiating to the back with elevated amylase and lipase.

Complications to monitor after thyroidectomy and the equipment kept at the bedside

Airway obstruction from edema or hematoma, hemorrhage pooling behind the neck, hypocalcemia and tetany, laryngeal nerve injury, and thyroid storm. Keep suction, oxygen, an emergency airway setup, and calcium gluconate available.

Rationale for withholding metformin around iodinated contrast administration

Contrast-associated kidney injury reduces metformin clearance and raises the risk of lactic acidosis. In at-risk clients, metformin is held at the time of contrast and for about 48 hours afterward, with renal function reassessed before restarting.

Why screening for shellfish allergy before contrast is not evidence based

Contrast reactions are not caused by iodine content in seafood. The meaningful risk factors are a prior reaction to contrast media, asthma, and other significant allergy history.

Monitoring and Prioritization

Therapeutic response versus priority adverse effect for furosemide

Response is weight loss, increased urine output, fewer crackles, and less edema. Adverse effects are hypokalemia, hyponatremia, hypomagnesemia, dehydration, orthostatic hypotension, and ototoxicity with rapid intravenous push.

Most reliable measure of fluid status, and how much fluid a 1 kilogram change represents

Daily weight, taken at the same time on the same scale after voiding in similar clothing. A 1 kilogram change corresponds to roughly 1 liter of fluid.

Adult urine output threshold that signals inadequate renal perfusion

Less than approximately 30 mL per hour, which should be reported.

Key antidote pairs to know

Heparin and protamine sulfate, warfarin and vitamin K, opioids and naloxone, benzodiazepines and flumazenil, acetaminophen and acetylcysteine, magnesium sulfate and calcium gluconate, digoxin and digoxin immune Fab.

Earliest sign of magnesium sulfate toxicity during infusion

Loss of the patellar deep tendon reflex, followed by respiratory depression, hypotension, and cardiac arrest. Oliguria compounds the risk because magnesium is renally excreted.

Prioritization sequence when several clients have abnormal findings

Airway, breathing, circulation, then neurologic change; acute over chronic; unstable over stable; unexpected over expected; and among unstable clients, the one whose problem is fastest to become fatal.

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