Posted by Andy Jagoda, MD in: What's Your Diagnosis , trackback
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Case Presentation: Acid-Base Disturbances: An Emergency Department Approach
It is Friday night and you have just received sign-out from your partner, who was finishing the swing shift, leaving you to function as the single provider in a critical access ED. Immediately after he leaves, local EMS radios in to give report about a patient en route:
“This is rescue 59 coming to your facility with a 56-year-old white woman with fever, chills, and lethargy. She is a patient being treated at University Hospital for ovarian cancer and last had chemotherapy 1 week ago. Her family says she has had fever up to 103°F since last night and recently had a CT scan showing a mass impinging on her ureter. Initial vital signs are: heart rate, 148 beats/min; blood pressure, 88/52 mm Hg; respiratory rate, 30 breaths/min; temperature 39° C; and oxygen saturation, 95% on 2L NC. We have not been able to obtain IV access, and we will be at your back door in 4 minutes.”
As you begin to prepare a resuscitation room, you appreciate that this febrile patient may be in septic shock, which is an inherently acidemic state. You wonder how best to determine whether an acidosis is purely due to sepsis or is confounded by additional acid-base disturbances. You also wonder what kind of IV fluids are best for resuscitation and whether there is a role for bicarbonate…
After your initial evaluation, the charge nurse informs you that there have been several new patient arrivals, and you review the track board, along with the results of their laboratory tests.
Ms. Whitehurst is presenting in septic shock from obstructive pyelonephritis after her pelvic mass grew to the point of ureteral compression. This is largely an anion gap acidosis without coexisting respiratory disturbance. For her hypotension, lactated Ringer’s solution was given as the initial resuscitation fluid, which is a reasonable initial choice. Existing evidence does not support administration of bicarbonate. On repeat check, her lactate was improving only minimally, and she remained hypotensive. Subsequently, she was placed on low-dose norepinephrine infusion and transferred to a tertiary care hospital with ICU and interventional radiology services for placement of a percutaneous nephrostomy tube.
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