Final answer:
Notify the physician of the lab results due to elevated serum digoxin and low serum potassium levels, which indicate potential digoxin toxicity and hypokalemia that can be worsened by the patient's current medication, furosemide.
Step-by-step explanation:
The most appropriate nursing action, given a patient with heart failure who is receiving digoxin and furosemide, and presents a serum digoxin level of 2.9ng/mL and a potassium level (K+) of 3.2mEq/L, would be to notify the physician of the lab results. This action is advised because the serum digoxin level is higher than the normal therapeutic range, which is generally between 0.5 to 2.0 ng/mL, indicating potential digoxin toxicity. Furthermore, the serum potassium level is below the normal range (3.5 to 5.0 mEq/L), which could exacerbate digoxin toxicity due to the relationship between hypokalemia and increased sensitivity to digoxin.
Loop diuretics, such as furosemide, inhibit the reabsorption of Na+ and Cl- in the ascending limb of the loop of Henle, which can lead to increased urine production and potential electrolyte imbalances, including hypokalemia. Therefore, withholding the furosemide until speaking with a physician might also be considered in this case, as it could further decrease the potassium levels, but the immediate action should be to report the abnormal lab values.