A young woman’s life was truly saved by the one and only… Dr. Molly Cutright!
A 28 year-old woman with no past medical history was brought in by EMS for altered mental status. EMS reported that the patient had “belly pain and was pregnant.” She was moaning and not making any sense so logically she was triaged to the hallway (irony). It was change of shift time and no one was paying attention to her, except… Dr. Cutright! Being the amazing ED clinician that she is, Dr. Cutright went to see if she could make the patient feel better with some pain meds. After talking to her, Molly thought she could have an ectopic but did not know why her mental status was altered. Molly noticed that her lips were super dry and she smelled like acetone. Cunningly, she asked for a fingerstick. Shockingly, the young woman’s glucose was greater than 500. Recognizing this patient as very ill, Dr. Cutright immediately had the patient transferred to the resuscitation room where she started an IV and sent off her first set of labs. The patient’s anion gap was tremendous and her pH was 6.7. This patient was clearly on the brink of death, and had Dr. Cutright not gone over to check on her or had not ordered a prompt fingerstick, this patient likely would have died in that hallway with nothing done for her. On a side note, the patient’s pregnancy test was negative. Strong save Dr. Cutright!
Now for a short review of DKA and some cutting edge pearls…
Pathogenesis:
TREATMENT: Aggressive Fluid Hydration Why? Dehydration leads to increased counter regulatory hormones which worsen the cycle of increased gluconeogenesis and worsening diuresis, dehydration and acidosis.1 On average, adults have a total body water deficit of 6L!! 2 Experts recommend starting rehydration with NS at 15-20cc/kg in the first 1-1.5 hours3. What about children? Bakes and colleagues performed an RCT of 50 pediatric patients with DKA and randomized patients to receive either a 10cc/kg initial fluid bolus versus 20cc/kg bolus. Patients in the higher-volume infusion rate had faster normalization of pH and bicarbonate and had decreased hospital length of treatment and time to discharge. Of note, there were no adverse outcomes including cerebral edema or pulmonary edema.1 While guidelines still recommend NS, outspoken FOAMed folks are recommending infusions of Lactated Ringer’s or Plasmalyte to avoid the hyperchloremic metabolic acidosis associated with use of normal saline. Curious about the pathophysiology? Lobo and colleagues explain that hyperchloremia induces vasoconstriction of the afferent renal arterioles leading to decreased GFR!4 Not only are we giving an acidic fluid when we give NS, but we’re decreasing GFR making it more difficult to excrete acids. Check out this nice literature review comparing the various fluids in DKA by Josh Farkas: DKA pearls12. Next time you have that DKA patient, why not reach for the LR? Potassium management Remember that although many DKA patients appear to have normal or hyperkalemia on initial laboratory results, they are actually total body potassium depleted. Due to acidosis, potassium is shifted from intracellular space to plasma and then excreted renally through hyperosmolar diuresis. What happens if you give IVF and insulin without monitoring potassium? Therefore, keep a close eye on potassium and replete aggressively because levels will drop once you initiate treatment. Per ADA guidelines, administration of insulin should be held until after potassium repletion if the K+ level is < 3.3 mEq/L. Replete with 20-30meq of potassium per hour until K+ >3.3 with a goal K+ of 4-5meq5. Insulin Administration of insulin should always occur AFTER checking K+. Insulin will decrease glucose, ketogenesis, close the anion gap, and increase the pH. Start the patient on an insulin drip at 0.1u/kg/hr. Drip vs. bolus? A prospective study by Goyal and colleagues found no difference in the rate of change of glucose, closure of the AG, length of stay in ED, and time to discharge. However there was 6-fold increase in episodes of hypoglycemia in the bolus group6. Similarly, Kitabchi et. al. found higher peak insulin levels and lower plateaus in patients given a bolus of insulin versus those started only on a drip, and there was no difference in time to normalized pH, glucose, and HCO3. Interestingly, they found the most desirable plateaus with an insulin drip rate of 0.14un/kg7. Some IM pearls: *This is not the patient to forget about once admitted, if still in the ED, make sure the K+ and glucose are checked regularly (q2 and q1 hours respectively)!!! *Remember to switch the fluids to D5/0.45NS when glucose <250mg/dL to prevent hypoglycemia when the patient is on an insulin drip. ETCO2 for DKA diagnosis?! – Yet another exciting use for our beloved end-tidal carbon dioxide (ETCO2) monitoring. Studies have shown that in patients with normally functioning respiratory systems, ETCO2 accurately estimates PaCO2 (ETCO2 levels are 2-5mmHg lower due to deadspace)8. Taghizadieh and colleagues compared ETCO2 and HCO3 levels in 262 patients with metabolic acidosis in the ED and found that there was a direct linear relationship between ETCO2 and HCO3 (even in patients with renal dysfunction)9. Fearon et al. examined 42 pediatric patients presenting with symptoms suspicious for DKA and studied the relationship between HCO3 and ETCO2. They found that an ETCO2 cutoff of <29 torr was 100% specific for ruling in DKA and an upper limit cutoff of >36 torr was 100% sensitive; ie. no one with a ETCO2 level of 36 or higher had DKA10. Soleimanpour et al. performed a similar study in adults and found a cutoff of >24 torr had a sensitivity and specificity of 90% for DKA11. More studies need to be performed to find the perfect cutoffs, but these studies suggest that ETCO2 can contribute to rapid diagnosis of this life-threatening condition. Also, it may quickly and cost-efficiently exclude patients who present with only hyperglycemia who do not need time-consuming and expensive DKA work-ups. However, caution should be used in patients with underlying lung disease. Also, even when using ETCO2, it is still important to trend glucose and electrolytes in these ill patients. Regardless, it is affordable, non-invasive, and appears to be a new diagnostic tool we can all start using today. Take home points: References:
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1 Comment
Kylie Birnbaum · November 1, 2016 at 1:49 pm
Really awesome post, Shibata, and congrats Cutright! Thanks for this excellent review of DKA and some great pearls- especially about switching to LR after your first NS bolus, and how an insulin bolus has more complications without better outcomes than just starting with a drip.