Overview

Mixed acid-base disorders are commonly encountered in clinical practice. They are frequently missed by healthcare professionals. On occasion, this has implications for patient management with lost opportunities for therapeutic intervention. In this course, we explain the significance of the ‘derived values’ (base excess and standard bicarbonate) reported on the arterial blood gas (ABG). In case studies, we show you how these values can help us detect the presence of mixed acid-base disturbances on the ABG and facilitate the diagnosis of unsuspected pathologies. We explain the limitations of the derived values. We demonstrate the application of the so-called ‘bedside rules’ in the detection of mixed acid-base disturbances on the ABG. We explain the role of ‘Winter’s formula’ in the assessment of the adequacy of respiratory compensation in metabolic acidosis and illustrate the clinical application of this formula. We show you how to apply and interpret the ‘delta ratio’ in cases of metabolic acidosis and illustrate how this value allows us distinguish between two major categories of causes of metabolic acidosis. We explain the nomenclature used on the ABG readout.

Faculty

Planner and Author: Dr John Seery MB PhD

• Consultant Physician at St. Vincent's University Hospital, Dublin, Ireland
• Lecturer at the School of Medicine and Medical Science, University College Dublin, Ireland
• Studied medicine at the University of Cambridge, United Kingdom
• A Natural Sciences graduate of Trinity College Dublin, Ireland
• PhD in Cell Biology from University College London, United Kingdom

Planner: Dr Karen Strahan PhD (University of Cambridge), Head of Editorial
Planner: Tommy O'Sullivan, CME Manager
 

Estimated Time to Complete

2.0 hours

Target Audience

• Physicians
• Nurses
• Nurse Practitioners
• Physician Assistants
• Paramedics

Learning Objectives

Upon successful completion of this activity, you will be able to:

• Explain the nature of the ‘derived values’ reported on the ABG
• Identify mixed acid-base disturbances on the ABG by applying the ‘bedside rules’
• Identify mixed acid-base disturbances on the ABG by analysis of the ‘derived values’, base excess and standard bicarbonate
• Use ‘Winter’s formula’ to assess the adequacy of compensation in a metabolic acidosis
• Calculate the delta ratio to identify mixed causes of acidosis
• Use appropriate terminology in the description of acid-base abnormality

Course Content

• Introduction
• Indentification of Mixed Acid-Base Disorders - Clues
• The Bedside Rules
• The Bedside Rules in Action
• Base Excess & Standard Bicarbonate
• Base Excess in a Clinical Case
• Derived Values - Terminology
• Derived Values - Limitations
• The Delta Ratio
• ABG Nomenclature
• Quiz
• Essential Reading

Release date

31-JUL-2020

Expiration date

30-JUL-2023

Instructions for Participation

Participants must complete the online activity during the valid period as noted above.
Follow these steps:

1. View videos in sequence
2. Read the papers on the essential reading list
3. Complete the quiz
4. Complete the activity evaluation form to provide feedback for continuing education purposes and for the development of future activities
5. Download the Certificate of Completion

Relevant Financial Disclosures

Planners and faculty for this activity have no relevant financial relationships with commercial interests to disclose.

Bibliography

Brandis K. The Great Trans-Atlantic Acid-Base Debate.
http://www.anaesthesiamcq.com/AcidBaseBook/ab9_5.php

Yartsev A. Assessment of Compensation: Boston and Copenhagen Methods.
https://derangedphysiology.com/main/cicm-primary-exam/required-reading/acid-base-physiology/Chapter%20605/assessment-compensation-boston-and-copenhagen-methods

Rastegar A.  Use of the ΔAG/ΔHCO₃⁻ Ratio in the Diagnosis of Mixed Acid-base Disorders. J Am Soc Nephrol 2007;18(9):2429-31.
https://jasn.asnjournals.org/content/18/9/2429

Additional Reading

Brandis K. Acid-Base Physiology. 9.6 Clinical Examples
https://www.anaesthesiamcq.com/AcidBaseBook/ab9_6.htm#cases

ACCME Accreditation Statement

Acadoodle, Ltd is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

Credit Designation Statement

AMA Physician’s Recognition Award

Acadoodle, Ltd designates this enduring material activity for a maximum of 2.0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.