From the Guidelines
Normal saline is the preferred initial intravenous fluid for treating diabetic ketoacidosis (DKA) due to its ability to rapidly expand intravascular volume, improve tissue perfusion, and enhance renal function. The use of normal saline in DKA is supported by the American Diabetes Association, as stated in the 2003 Diabetes Care guidelines 1. According to these guidelines, initial fluid therapy in adult patients with DKA should be directed toward expansion of the intravascular and extravascular volume and restoration of renal perfusion, with isotonic saline (0.9% NaCl) infused at a rate of 15–20 ml kg–1 body wt h–1 or greater during the first hour.
Key benefits of using normal saline in DKA include:
- Rapid expansion of intravascular volume to improve tissue perfusion and enhance renal function
- Correction of hyperglycemia by improving renal perfusion and increasing glucose excretion
- Addressing the sodium deficit commonly present in DKA patients, despite initial laboratory values sometimes showing normal or elevated sodium levels due to pseudohyponatremia from hyperglycemia
- Providing a safe and effective way to rehydrate patients, with the potential to switch to dextrose-containing solutions once the patient is hemodynamically stable and serum glucose falls below 250 mg/dL.
While there may be concerns about normal saline worsening acidosis by causing hyperchloremic metabolic acidosis, the benefits of volume restoration and improved renal function outweigh these concerns, as noted in the guidelines 1. Overall, the use of normal saline as the initial intravenous fluid in DKA is a well-established practice that prioritizes the patient's morbidity, mortality, and quality of life.
From the Research
Rationale for Normal Saline in Diabetic Ketoacidosis
- Normal saline (NS) has been the traditional fluid of choice for both volume resuscitation and deficit replacement in diabetic ketoacidosis (DKA) due to its ability to restore intravascular, interstitial, and intracellular compartments 2.
- The use of NS in DKA aims to reduce hyperglycemia by decreasing counter-regulatory hormones, enhancing renal glucose clearance, and augmenting insulin sensitivity 2.
- However, the liberal chloride content in NS has been a concern, as it may lead to hyperchloremic acidosis and delay DKA resolution 3, 4.
Comparison with Other Fluids
- Balanced crystalloids, such as Sterofundin, have been shown to be a superior alternative to NS in DKA, with faster correction of pH and shorter time to DKA resolution 4.
- Other studies have compared NS with Hartmann's solution, a balanced salt solution, and found no significant difference in time to normalize acid-base status, but a potential benefit in severe DKA cases 5.
- The use of low chloride solutions has also been explored, with some studies suggesting faster correction of pH and comparable time to DKA resolution compared to NS 3.
Considerations for Fluid Therapy in DKA
- The goal of fluid therapy in DKA is to restore circulating volume, improve tissue perfusion, and avoid major osmotic shifts, correct electrolyte imbalances, and prevent cerebral or pulmonary edema 2, 6.
- A conservative deficit assumption ranging from 6.5% to 8.5% is preferred, and the choice of fluid should be based on the individual patient's needs and the potential risks and benefits of each fluid type 2, 4.