McKenna's Pharmacology for Nursing, 2e

689

C H A P T E R 4 4 Cardiotonic agents

Care considerations for people receiving cardiac glycosides

■ ■ Monitor apical pulse for 1 full minute before administering the drug to monitor for adverse effects. Withhold the dose if the pulse is less than 60 beats/minute in an adult or less than 90 beats/ minute in an infant; retake the pulse in 1 hour. If the pulse remains low, document it, withhold the drug and notify the prescriber because the pulse rate could indicate digoxin toxicity (see Table 44.2 for Signs and symptoms). ■ ■ Monitor the pulse for any change in quality or rhythm to detect arrhythmias or early signs of toxicity. ■ ■ Check the dose and preparation carefully because digoxin has a very small margin of safety and inadvertent drug errors can cause serious problems. ■ ■ Check paediatric dose with extreme care because children are more apt to develop digoxin toxicity. Have the dose double-checked by another nurse or midwife before administration. ■ ■ Follow dilution instructions carefully for intravenous use; use promptly to avoid drug degradation. ■ ■ Administer intravenous doses very slowly over at least 5 minutes to avoid cardiac arrhythmias and adverse effects. ■ ■ Avoid intramuscular administration, which could be quite painful. ■ ■ Arrange for the person to be weighed at the same time each day, in the same clothes, to monitor for fluid retention and HF. Assess dependent areas for oedema; note the amount and degree of pitting to evaluate the severity of fluid retention. ■ ■ Avoid administering the oral drug with food or antacids to avoid delays in absorption. ■ ■ Maintain emergency equipment on standby: potassium salts, lignocaine ( for treatment of arrhythmias ), phenytoin ( for treatment of seizures ), atropine ( to increase heart rate ) and a cardiac monitor, in case severe toxicity should occur. ■ ■ Obtain digoxin level as ordered; monitor the person for therapeutic digoxin level (0.5 to 2 ng/mL) to evaluate therapeutic dosing and to monitor for the development of toxicity. ■ ■ Provide comfort measures to help the person tolerate drug effects. These include small, frequent meals to help alleviate GI upset or nausea ; access to bathroom facilities if GI upset is severe and to accommodate increased urination related to increased cardiac output ; safety precautions to reduce the risk of injury secondary to weakness and drowsiness ; adequate lighting to accommodate vision changes if they occur ; positioning for

Assessment: History and examination

■ ■ Assess for contraindications or cautions: known allergies to any digitalis product to avoid hypersensitivity reactions ; impaired kidney function, which could alter the excretion of the drug ; ventricular tachycardia or fibrillation, which require treatment with other life-saving drugs ; heart block, sick sinus syndrome or IHSS, which could be exacerbated by the drug ; acute MI, which could lead to increased muscle damage and infarction ; electrolyte abnormalities (increased calcium, decreased potassium or decreased magnesium), which could alter the action potential and drug effects ; and current status of pregnancy or breastfeeding. ■ ■ Perform a physical assessment to establish baseline status before beginning therapy, determine the effectiveness of therapy and evaluate for any potential adverse effects. ■ ■ Obtain the person’s weight, noting any recent increases or decreases, to determine the person’s fluid status. ■ ■ Assess cardiac status closely, including pulse and blood pressure, to identify changes requiring a change in dosage of the drug or the presence of adverse effects ; and auscultate heart sounds, noting any evidence of abnormal sounds, to identify conduction problems. ■ ■ Inspect the skin and mucous membranes for colour, and check nail beds and capillary refill for evidence of perfusion. ■ ■ Monitor affect, orientation and reflexes to evaluate central nervous system (CNS) effects of the drug. ■ ■ Assess the person’s respiratory rate and auscultate lungs for evidence of adventitious breath sounds to monitor for evidence of left-sided heart failure. ■ ■ Examine the abdomen for distension; auscultate bowel sounds to evaluate GI motility. ■ ■ Assess voiding patterns and urinary output to provide a gross indication of renal function. ■ ■ Obtain a baseline electrocardiogram (ECG) to identify rate and rhythm and evaluate for possible changes. ■ ■ Monitor the results of laboratory tests, including serum electrolyte levels and renal function tests, to determine the need for possible dose adjustment. Implementation with rationale ■ ■ Consult with the prescriber about the need for a loading dose when beginning therapy to achieve desired results as soon as possible.