Acid-Base Disturbances: An Emergency Department Approach -

Acid-Base Disturbances: An Emergency Department Approach
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Publication Date: June 2020 (Volume 22, Number 6)

CME Credits: 4 AMA PRA Category 1 Credits™, 4 ACEP Category I credits, 4 AAFP Prescribed credits, and 4 AOA Category 2-A or 2-B CME credits. CME expires 6/01/2023.


Michael Boniface, MD
Instructor in Emergency Medicine, Mayo Clinic College of Medicine; Consultant, Department of Emergency Medicine, Mayo Clinic Florida, Jacksonville, FL
Ivan Porter, MD
Assistant Professor of Medicine, Mayo Clinic College of Medicine; Consultant, Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic Florida, Jacksonville, FL

Peer Reviewers

Daniel J. Egan, MD
Associate Professor, Vice Chair of Education, Department of Emergency Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, NY
Gabriel Wardi, MD, MPH
Assistant Clinical Professor, Department of Emergency Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, San Diego, CA


Acid-base disturbances are physiological responses to a wide variety of underlying conditions and critical illnesses. Homeostasis of acid-base physiology is complex and interdependent with the function of the lungs, kidneys, and endogenous buffer systems. Traditionally, these disturbances have been classified in terms of being caused by either a primary respiratory or a metabolic insult and by chronicity and compensation. While existing literature consists largely of physiology reviews, several well-designed studies and clinical practice guidelines provide relevant new perspectives on interpreting and managing acid-base disturbances. This review outlines several approaches to characterizing disturbances, with a case-based format and algorithms to aid in diagnostic testing and interpretation of arterial blood gases.

Excerpt From This Issue

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…

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