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Digoxinis a cardiac glycoside that exerts a positive inotropic and negative chronotropic effect by inhibiting the sodium-potassium ATPasepump. This mechanism increases intracellular calcium, enhancing myocardial contractility while slowing the heart rate to improve cardiac outputin heart failure. Therapeutic monitoring is essential because a narrow therapeutic index exists, and electrolyte imbalances, particularly hypokalemia, significantly increase the risk of digitalis toxicity and life-threatening dysrhythmias.

Rationale:

The current potassium levelof 3.2 mEq/L is unexpectedand clinically significant as it falls below the physiological range of 3.5 to 5.0 mEq/L. While digoxin itself does not typically cause potassium loss, it competes with potassium for binding sites on the ATPase pump. Low serum potassium levels sensitize the myocardium to the drug, dramatically increasing the risk of digoxin toxicityeven when the drug level remains within the therapeutic range.

The digoxin levelof 0.8 ng/mL is expectedas it sits at the lower end of the standard therapeutic window of 0.8 to 2.0 ng/mL. This concentration indicates that the medication has reached a steady state in the plasma without exceeding safety thresholds. Maintaining this therapeutic levelis crucial for managing heart failure symptoms effectively while preventing the gastrointestinal and neurological complications associated with excessive cardiac glycoside accumulation.

The reported urinary concernregarding increased output is an expectedtherapeutic outcome of improved cardiac performance. As digoxin increases the force of myocardial contraction, renal perfusion is enhanced, which stimulates the kidneys to increase glomerular filtrationand urine production. This natural diuresis helps the body mobilize and excrete excess fluid volume that had previously accumulated in the tissues due to pump failure.

The current heart rateof 82/min is expectedand demonstrates a positive response to the negative chronotropic effects of cardiac glycoside therapy. Digoxin slows the conduction through the atrioventricular nodeand increases vagal tone, which effectively lowers the heart rate from the initial tachycardic state of 102/min. A resting heart rate between 60 and 100/min indicates that the medication is successfully reducing myocardial workload.

The reported current leg findingsof decreased swelling are expectedbecause they indicate a reduction in peripheral edema. By improving the heart's ability to circulate blood efficiently, digoxin reduces the venous hydrostatic pressure that causes fluid to leak into the interstitial spaces of the lower extremities. This clinical improvement correlates with the client's report of easier breathing and reflects successful management of congestive symptoms.

The client presents with hypoglycemia (capillary glucose 64 mg/dL), hypotension (90/70 mm Hg), tachycardia, and fever. They are scheduled to receive both metoprolol and insulin aspart, which can further lower heart rate, blood pressure, and glucose levels. Priority nursing care requires immediate correction of life-threatening metabolic instability before administering medications that may worsen the condition.

Rationale:

• Capillary glucose: The capillary glucose of 64 mg/dL indicates hypoglycemia, which is an immediate priority because it can rapidly progress to neurological impairment, seizures, or loss of consciousness. Insulin aspart is scheduled for administration, but giving insulin in the presence of low blood glucose would worsen hypoglycemia. The nurse must first address and correct the glucose level to prevent acute neurological deterioration. Stabilizing blood sugar takes precedence over other abnormal findings in this scenario.

• Blood pressure: The blood pressure of 90/70 mm Hg indicates hypotension, which may compromise tissue perfusion to vital organs such as the brain, heart, and kidneys. Metoprolol is a beta-blocker that can further lower blood pressure and heart rate, increasing the risk of hemodynamic instability. After correcting hypoglycemia, blood pressure must be addressed to ensure safe medication administration.

• Reported pain: A pain level of 4/10 is considered mild to moderate and is not the highest priority in this situation. Although pain management is important, it does not pose an immediate threat to life compared to hypoglycemia or hypotension. The client’s metabolic and cardiovascular instability must be corrected first before addressing comfort measures. Pain can be reassessed and treated after stabilization.

• Temperature: The elevated temperature of 38.2°C (100.8°F) reflects an infectious process consistent with pneumonia, but it is not the most immediate life-threatening concern. Fever contributes to increased metabolic demand but does not require urgent correction before hypoglycemia or hypotension. Antipyretics and antibiotic therapy can address this once the client is hemodynamically stable. Priority remains with glucose and perfusion issues.

• Heart rate: The heart rate of 104/min is mildly elevated and likely secondary to fever, infection, or hypoglycemia. While it requires monitoring, it is not as critical as the low blood glucose or low blood pressure in terms of immediate risk. Tachycardia is compensatory and should not be treated in isolation. Addressing underlying instability will normalize the heart rate.

Spironolactoneis a potassium-sparing diuretic that functions as an aldosterone antagonistin the distal convoluted tubule and collecting duct. It promotes the excretion of sodium and water while retaining potassium, making it effective for hypertension but dangerous in the presence of renal insufficiency. Significant contraindications include pre-existing hyperkalemiaor concurrent use of other medications that inhibit the renin-angiotensin-aldosterone system, as these combinations exponentially increase the risk of lethal cardiac dysrhythmias.

Rationale:

A. The client is currently taking lisinopril, an ACE inhibitor, which also increases serum potassium by suppressing aldosterone secretion. Combining lisinopril with spironolactone creates a synergistic effect that leads to severe hyperkalemia. This drug-drug interaction is a major clinical concern because both agents reduce the kidneys' ability to excrete potassium. The nurse must report this concurrent therapy to prevent potential cardiac toxicityresulting from excessive potassium accumulation.

B. The client's potassium level of 5.6 mEq/L already indicates hyperkalemia, as it exceeds the normal physiological limit of 5.0 mEq/L. Administering spironolactone to a client with an already elevated potassium concentration is strictly contraindicated. Increasing the potassium burden through potassium-sparingeffects could lead to peaked T waves, conduction blocks, or asystole. This laboratory finding must be addressed and corrected before any further potassium-retaining medications are administered.

C. A BUN(blood urea nitrogen) of 30 mg/dL signifies impaired renal clearance and decreased glomerular filtration. Elevated nitrogenous waste products often indicate that the kidneys are unable to maintain proper electrolyte balance. Since spironolactone relies on renal excretion and affects renal tubular transport, its use in a client with azotemia is highly risky. This finding suggests the client is at an increased risk for metabolic imbalancesif the diuretic is initiated.

D. A creatininelevel of 2 mg/dL is double the upper limit of the normal range, indicating significant renal dysfunction. Spironolactone is generally contraindicated or requires extreme caution in patients with a creatinine clearance that is significantly reduced. Impaired renal function prevents the body from managing the potassium-sparing effects of the drug, leading to a rapid and dangerous rise in serum electrolytes. This objective marker of kidney failuremakes the new prescription inappropriate for the client's current clinical status.

Hyperkalemiais a critical electrolyte disturbance defined by a serum potassium level exceeding 5.0 mEq/L, which alters the resting membrane potentialof excitable tissues. This condition often results from renal failure, metabolic acidosis, or cellular injury, leading to cardiac dysrhythmiasand neuromuscular weakness. Clinical management involves stabilizing the myocardium, shifting potassium intracellularly, and facilitating the definitive excretionof the excess cation from the body to prevent cardiac arrest.

Rationale:

Administering sodium polystyrenerectally is appropriateas it acts as a cation-exchange resin to remove excess potassium from the body. It works in the large intestine by exchanging sodium ions for potassium ions, which are then excreted through the feces. This provides a definitive method for lowering the total body potassiumload in a client with a serum level of 6 mEq/L.

Administering potassium chloride IV is inappropriateand life-threatening for this client because their serum potassium level is already critically elevated at 6 mEq/L. Adding more exogenous potassium would exacerbate the hyperkalemic state, leading to worsening cardiac conduction delays or ventricular fibrillation. The primary goal for this client is potassium reduction, not supplementation or replacement.

Administering insulin IVis appropriatebecause it stimulates the sodium-potassium ATPase pump, facilitating the rapid shift of potassium from the extracellular fluid into the intracellular compartment. This provides a temporary but life-saving reduction in serum potassium levels. Intravenous dextrose is typically co-administered to prevent hypoglycemiaunless the client’s blood glucose is already significantly elevated.

Administering hydralazine IVis inappropriatebecause this client is already experiencing low blood pressure, with a reading of 98/54 mm Hg at 1100. Hydralazine is a direct-acting vasodilatorused to treat hypertension by relaxing vascular smooth muscle. Giving a vasodilator to a hypotensive client would lead to severe hemodynamic collapse and further compromise organ perfusion.

Administering calcium gluconate IVis appropriateas a first-line emergency intervention to stabilize the myocardial cell membrane. While calcium does not lower the serum potassium level, it antagonizes the cardiotoxic effects of hyperkalemia by increasing the threshold potential. This helps prevent lethal arrhythmias, such as the progression from the current peaked T waves to sinusoidal rhythmsor asystole.