Final answer:
The nurse should first check the chart for the most recent blood potassium level when noting lengthening QRS intervals in a patient with acute kidney injury, as it may indicate a serious electrolyte imbalance, particularly hyperkalemia, which requires immediate attention.
Step-by-step explanation:
If a patient with acute kidney injury (AKI) is exhibiting lengthening QRS intervals on an electrocardiogram (ECG), the nurse should first check the chart for the most recent blood potassium level. Lengthening QRS intervals may indicate changes in the electrical conduction of the heart which can be a sign of electrolyte imbalance, particularly hyperkalemia, which is a common complication in AKI. Since elevated potassium can have serious cardiac implications, it is essential to identify and address this issue promptly. If high potassium levels are confirmed, it would be crucial to notify the patient's health care provider immediately for appropriate management.
Additionally, considering the ECG changes and potential diagnosis of acute renal failure (ARF) or chronic kidney disease (CKD), it's important to be aware of any abnormal renal function test results, such as elevated serum creatinine and blood urea nitrogen (BUN) levels. Thus, after assessing potassium levels, reviewing the patient's BUN, creatinine, and oliguria status may provide further insights into the severity of AKI and guide subsequent treatment decisions.