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Deciphering Acid-Base Disorders

Derangements in acid-base status are commonly discovered on routine emergency department evaluation and often suggest the presence of severe underlying disease. Many acute conditions can disrupt homeostatic mechanisms used to buffer and excrete acid, and these changes may necessitate immediate intervention...

With regard to pH, correlation between peripheral venous and arterial blood samples is well established; pH is approximately 0.03-0.05 units lower in peripheral venous samples, whereas PCO2 is 4-5 mmHg higher. This correlation is less reliable in patients with shock or other cardiopulmonary compromise.

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Featured

 Acid-Base Disturbances: An Emergency Department Approach

Acid-base disturbances are diagnosed from a patient’s chemistry and blood gas results, but there are multiple approaches to determining the underlying causes and initiating treatment. This issue presents a summary of the chemistry and physiology of acid-base disturbances and uses a workbook-style format of 8 real-life cases to illustrate the approaches to diagnosing and managing these disorders. Algorithms for acidemia and alkalemia reinforce the stepwise approach.

Articles of Interest

Dr. Michael Chansky: Acid-Base (Made Easy)

When you find someone as obsessed with acid-base dysequilebria as Dr. Chansky, you have no choice but to listen to him discuss the fundamentals of pH-ology and the evaluation and management of these patients.

Acid Base Sheet

STEP I‐GET LABS Blood Gas (Art or Venous), Lactate, Albumin, Beta-HydroxyButyrate, Chemistry Panel

Acid-Base Disorder? Mind the Gaps

A step-wise emergency approach to acid-base disorders – including the “Rule of 15” and the “Delta Gap” formulas – can help uncover processes that are hidden in the labs.

Acid-Base Disturbance

The body has three defense mechanisms to maintain normal pH: the buffering system, the respiratory system, the renal system. Among the three systems, the buffering is the fastest means of preventing disturbances in pH. It was likened to a ”sponge” that soaks up excessive hydrogen ions and releases them when there’s a deficient concentration. Several buffering agents bind hydrogen ions reversibly. These include bicarbonate, ammonia, hemoglobin and plasma proteins.

Acid-Base Disturbances: 5 Rules That Can Simplify Diagnosis

Fortunately, the reputed complexity of interpreting acid-base disturbances can be greatly simplified. Here we present 5 easy rules for interpreting clinical acid-base physiology, along with straightforward algorithms that provide a step-by-step approach to various metabolic derangements.

CRACKCast E124 – Acid-Base Disorders

Patients with an acute severe metabolic acidosis rely on a robust respiratory compensation; in these cases, the adequacy of the ventilatory response should be assessed and augmented, with non-invasive or invasive ventilation, if needed.

Disorders of Acid-Base Balance: New Perspectives

This review aims to give new and comprehensive perspective on understanding acid-base balance and identifying associated disorders. All metabolic acid-base disorders can be approached in the context of the relative losses or gains of electrolytes or a change in the anion gap in body fluids.

Overview of acid-base and electrolyte disorders

There are multiple reasons why disorders of blood chemistry may develop, including respiratory or renal disease, obesity, and medication. Resulting imbalances include acidosis (pH <7.35), alkalosis (pH >7.45), and high or low levels of key electrolyte ions, including sodium, potassium, calcium, magnesium, chloride, hydrogen phosphate, and hydrogen carbonate (bicarbonate). They may be acute or chronic, may occur with varying degrees of severity, and may not be sufficiently counteracted by the body's regulatory/compensatory mechanisms.

Resources

Facing acid–base disorders in the third millennium – the Stewart approach revisited

Acid–base disorders are common in the critically ill. Most of these disorders do not cause harm and are self-limiting after appropriate resuscitation and management. Unfortunately, clinicians tend to think about an acid–base disturbance as a “disease” and spend long hours effectively treating numbers rather than the patient.