Guidelines from the Brits
Most of Our Protocol is Based on the Revised Joint British DKA Management Guidelines
Why Did We Choose 0.15 units/kg/hr as our starting Insulin Infusion Rate?
The most evidence based dose is probably 0.14, we just rounded up by 0.01. The evidence for the higher fixed starting dose is based on this study (10.2337/dc08-0509) and is predicated on our avoidance of a priming IV Push.
Avoid Having to Waste an ICU Bed
Variations in the use of ICU for DKA (Crit Care Med 2012;40:2009)
Am J of Medicine 1999;106:399
Na + (0.024 * (plasma glucose – 100))
Avoid normal saline
A common phenomenon observed when starting a DKA resuscitation with normal saline (NS) is worsening of the patient’s acidosis with decreasing bicarbonate levels (example below). This occurs despite an improvement in the anion gap, and is explained by a hyperchloremic metabolic acidosis caused by bolusing with NS. This could be a real problem for a patient whose initial bicarbonate level is extremely low.1 A while ago I made the switch from NS to lactated ringers (LR) for resuscitation of DKA patients, and have not observed this phenomenon when using LR.
Example of the effect of normal saline resuscitation during the initial phase of DKA resuscitation. This patient received approximately 3 liters normal saline between admission labs and the next set of labs as well as an insulin infusion, all textbook management per American Diabetes Association guidelines. The anion gap decreased from 33 mEq/L to 30 mEq/L, indicating improvement of ketoacidosis. However, the bicarbonate decreased from 8 mEq/L to 5 mEq/L due to a hyperchloremic metabolic acidosis caused by the normal saline. Note the increase in chloride over four hours. Failure of the potassium to decrease significantly despite insulin infusion may reflect potassium shifting out of the cells in response to the hyperchloremic metabolic acidosis.
There is only one randomized controlled trial comparing NS to LR for resuscitation in DKA (Zyl et al, 2011). These authors found a trend towards faster improvement in pH when using LR compared to NS (p = 0.076). They also found that patients in the NS group experienced a decrease in average serum bicarbonate during the first hour of treatment (from 8.86 to 8.21 mEq/L), whereas patients in the LR group experienced an increase in average serum bicarbonate during the first hour of treatment (from 7.71 mEq/L to 8.83 mEq/L). Although the authors concluded that this was a negative study, the data suggests an advantage of using LR in correcting the acidosis.
There is better data supporting the use of Plasmalyte in DKA. Plasmalyte is a balanced crystalloid with a strong ion difference of 50 mM which will induce a gentle metabolic alkalosis.2 Given that patients with DKA generally develop a non-anion-gap metabolic acidosis (more on this below), this fluid may be ideal for DKA patients. Rinaldo Bellomo’s research group in Australia performed a retrospective analysis of patients with DKA who received predominantly NS or Plasmalyte (Chua et al 2012). Patients who received plasmalyte had more rapid improvement in their serum bicarbonate. There was no difference in the strong ion gap (an index of ketoacids, similar to the anion gap), indicating that the higher bicarbonate in the plasmalyte group was due to avoidance of a NS-induced hyperchloremic acidosis combined with the gentle alkalinizing effect of plasmalyte. Mahler et al 2011 performed a prospective randomized controlled study of NS vs. Plasmalyte which also showed higher bicarbonate levels and less hyperchloremia in the Plasmalyte group. Note that there are other proprietary crystalloids available with a composition nearly identical to Plasmalyte (i.e. Normosol R).
Bottom line? Normal saline induces a hyperchloremic acidosis which drops bicarbonate levels in the initial phase of DKA resuscitation, and is probably not the ideal fluid to use. Plasmalyte may be the best choice since it is mildly alkalinizing and supported by the most evidence. If you don’t have Plasmalyte or Normosol, LR works well.
- THAM Monograph
- Most Recent Study (J NEPHROL 2005; 18: 303-307) sodium bicarbonate is contraindicated and THAM preferred in patients with mixed acidosis with high PaCO2 levels.
- Review (acta anaes scand 2000;44:524)
- American Journal of Respiratory and Critical Care Medicine, Vol. 161, No. 4 (2000), pp. 1149-1153.doi: 10.1164/ajrccm.161.4.9906031
Administer the Long-Acting Insulin Early in the DKA Treatment(26013711)
Profound hypokalemia in diabetic ketoacidosis: a therapeutic challenge. Authors Murthy K1, Harrington JT, Siegel RD. Author information Journal Endocr Pract. 2005 Sep-Oct;11(5):331-4.
Should We Give Sodium Bicarbonate for Acidosis?
- For elderly pts, insulin naive pts, renal failure pts, low BMI pts, or NPO, use low dose: 0.15 Units/kg;
- For remainder, use standard dosing: 0.25 Units/kg
- For Type II Diabetics, Obese pts, Pts on Steroids, Infected Pts, Pts on pressors, & pts who required high drip rates: 0.3 Units/kg
Beware of Euglycemic DKA
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