Is administering an additional 500 cc of normal saline at 50 mL/hour appropriate for a patient with chronic kidney disease, acute kidney injury, and hyperchloremic metabolic acidosis, who has shown partial improvement in renal function after prior fluid resuscitation, but now has worsening hyperglycemia and hyperchloremia?

Administering Additional Normal Saline is NOT Appropriate in This Clinical Context

The plan to administer an additional 500 cc of normal saline should be reconsidered and changed to a balanced crystalloid solution (Lactated Ringer's or Plasma-Lyte) instead, given the patient's worsening hyperchloremic metabolic acidosis, chronic kidney disease with acute kidney injury, and elevated chloride level of 115 mEq/L. 1, 2

Why Normal Saline Should Be Avoided

• Normal saline will worsen the existing hyperchloremic metabolic acidosis through further chloride accumulation and bicarbonate dilution, particularly dangerous in patients with pre-existing renal impairment who have reduced ability to handle acid-base disturbances. 1, 2

• The patient's chloride has already increased from 109 to 115 mEq/L after the initial 500 cc normal saline bolus, and the bicarbonate has dropped from 23 to 19 mEq/L, demonstrating clear iatrogenic worsening of the metabolic acidosis. 2

• Normal saline causes renal vasoconstriction and is associated with higher rates of major adverse kidney events compared to balanced crystalloids, which is particularly concerning given this patient's eGFR of only 16.5 mL/min. 3, 1, 2

• If normal saline must be used for any reason, it should be limited to a maximum of 1-1.5 L total, and this patient has already received 500 cc. 1, 2

Recommended Alternative Approach

Switch immediately to a balanced crystalloid solution (Lactated Ringer's or Plasma-Lyte) for the additional 500 cc fluid bolus at 50 mL/hour. 1, 2

Rationale for Balanced Crystalloids:

• Balanced solutions contain physiological chloride concentrations (approximately 109-110 mEq/L in Lactated Ringer's, 98 mEq/L in Plasma-Lyte) compared to 154 mEq/L in normal saline, preventing further chloride accumulation. 2

• The SMART trial (15,802 ICU patients) demonstrated that balanced crystalloids resulted in significantly lower rates of major adverse kidney events compared to normal saline (14.3% vs 15.4%, p<0.05). 3, 2

• Lactated Ringer's contains lactate that metabolizes to bicarbonate, which can help correct the metabolic acidosis rather than worsen it. 2, 4

• The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines specifically recommend isotonic crystalloids rather than colloids for volume expansion in patients at risk for or with acute kidney injury. 1

Addressing Potential Concerns

Concern About Lactate in Lactated Ringer's:

• Lactate can be metabolized to bicarbonate in most patients and helps correct metabolic acidosis, even in patients with renal impairment. 2

• Only avoid lactate-buffered solutions in patients with severe lactic acidosis or liver failure, which is not mentioned in this case. 2

Concern About Potassium Content:

• The potassium content in balanced solutions (4-5 mEq/L) is not contraindicated unless severe hyperkalemia exists. 2

• This patient's potassium is 4.3 mEq/L (normal range), so balanced crystalloids are safe. 2

Concern About Hyperglycemia:

• The worsening hyperglycemia (214 mg/dL) is likely stress-related and should be managed with glucose monitoring and insulin coverage, not by avoiding balanced crystalloids. 2

Critical Monitoring Parameters

Continue the following monitoring as planned, but with balanced crystalloids instead:

• Serial arterial or venous blood gases to assess acid-base status and response to balanced crystalloid therapy. 2

• Serum electrolytes including chloride levels to ensure chloride is trending downward rather than continuing to rise. 2

• Renal function markers (BUN, creatinine, eGFR) and urine output to assess kidney response to volume resuscitation. 1, 2

• Daily fluid balance to avoid volume overload, particularly important given the severely reduced eGFR of 16.5 mL/min. 3, 1

Clinical Significance of Current Acidosis

• The bicarbonate of 19 mEq/L with anion gap of 8 confirms non-anion gap (hyperchloremic) metabolic acidosis, which is iatrogenic from the normal saline administration. 2

• Metabolic acidosis is an independent risk factor for progression of acute kidney injury and hospital mortality, making correction of the underlying cause (excessive chloride) essential. 5

• Hyperchloremia (chloride >110 mEq/L) is associated with increased 30-day mortality risk in critically ill patients. 2

Summary of Recommended Plan Modification

Replace the ordered 500 cc normal saline with 500 cc of Lactated Ringer's or Plasma-Lyte at 50 mL/hour, maintaining all other aspects of the monitoring plan including repeat BMP the following day. 1, 2 This modification will provide the necessary volume resuscitation while preventing further worsening of the hyperchloremic metabolic acidosis and potentially reducing the risk of additional kidney injury. 3, 1, 2