Interpreting Acid-Base Imbalance in a Client with Newly Diagnosed Diabetes Mellitus and Left-Sided Heart Failure


Assessing and interpreting acid-base balance in a client with complex comorbidities, such as newly diagnosed diabetes mellitus and left-sided heart failure, is a critical nursing responsibility. In this guide, we will delve into the comprehensive assessment of a client who presents with low blood pressure, respiratory changes, altered mental status, headache, and nausea. The focus will be on interpreting the client’s acid-base balance based on the provided serum laboratory results, shedding light on the underlying pathophysiology and its implications for nursing care.

Interpreting Acid-Base Balance:

The client’s presentation and laboratory results indicate a complex acid-base disturbance. Let’s analyze each component:

  1. pH: The pH value of 7.34 is slightly below the normal range (7.35-7.45), indicating acidemia (an excess of hydrogen ions in the blood).
  2. HCO3- (Bicarbonate): The bicarbonate level of 19 mEq/L is within the normal range (22-28 mEq/L), suggesting a normal or slightly decreased bicarbonate concentration.
  3. PaCO2 (Partial Pressure of Carbon Dioxide): The PaCO2 value of 35 mm Hg is within the normal range (35-45 mm Hg), indicating normal or slightly decreased levels of carbon dioxide in the blood.
  4. Anion Gap: The anion gap is calculated using the formula (Na+ – [HCO3- + Cl-]). In this case, the calculated anion gap is 30 mEq/L, which is significantly elevated. A normal anion gap is typically less than 12 mEq/L.

Now, let’s interpret these findings:

  • The low pH (acidemia) suggests an acid-base imbalance favoring acidity.
  • The normal or slightly decreased bicarbonate (HCO3-) level indicates a primary non-compensated metabolic acidosis. This means that the body is unable to adequately compensate for the excess acid.
  • The normal PaCO2 suggests that respiratory compensation has not occurred. In a metabolic acidosis, the respiratory system should respond by increasing the rate and depth of breathing (known as Kussmaul respirations) to eliminate carbon dioxide and help raise the pH. The client’s increased respiratory rate and depth align with this compensation.

Based on these findings, the acid-base disturbance in this client can be identified as a primary non-compensated metabolic acidosis. This metabolic acidosis is likely due to multiple factors, including uncontrolled diabetes mellitus and left-sided heart failure.

Possible Causes:

  1. Diabetic Ketoacidosis (DKA): Uncontrolled diabetes can lead to the production of ketones (acidic byproducts) in the absence of sufficient insulin. This can result in a metabolic acidosis.
  2. Lactic Acidosis: Left-sided heart failure can cause inadequate tissue perfusion, leading to the production of lactic acid and contributing to the acidosis.

Clinical Implications:

  • The client’s acidemia and metabolic acidosis require immediate intervention and treatment to correct the underlying causes, such as insulin administration for diabetes control and management of heart failure.
  • Close monitoring of the client’s vital signs, respiratory rate, and mental status is crucial.
  • Correction of the acid-base imbalance is essential to prevent further complications, including potential organ dysfunction.


Interpreting the acid-base imbalance in a client with newly diagnosed diabetes mellitus and left-sided heart failure reveals a primary non-compensated metabolic acidosis. This complex disturbance highlights the importance of prompt intervention to address the underlying causes and restore acid-base equilibrium for optimal patient outcomes.


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