Acid-Base and Electrolyte Case Study

A nurse is taking care of an 85-year-old woman in a hospital-based skilled nursing facility. In the report, the nurse is told the patient has not been breathing well for the past 2 days. She has been lethargic, her skin is warm and dry, and she has a decreased urine output. The following laboratory findings were returned from the laboratory immediately after morning report:

Blood Chemistries

Na: 147
Cl: 110
K: 4.0
Arterial Blood Gases

pH: 7.33
PCO2: 48
HCO3: 27
PO2: 96

Urine Specific Gravity: 1.040
Address the following:

Identify each of the abnormal laboratory findings in the above results. Specify how they differ from a normal range and identify what condition each abnormality indicates.
What specific electrolyte disturbance does the patient have?
What clinical manifestations would the nurse expect to see with this electrolyte abnormality presented above?
If the patient had an increase in her potassium level, for what clinical manifestations would the nurse monitor?
What blood gas abnormality is seen in this patient? Discuss the rationale for your answer.
What are the three major mechanisms of pH regulation?

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Acid-Base and Electrolyte Case Study

In the case scenario, a nurse manages an 85-year-old female patient with a history of breathing difficulties for two days. The patient is lethargic, skin is dry and warm, and has a reduced urine output. Blood chemistry results include Cl-110, Na-147, and K- 4.0. Arterial Blood Gas results include pH-7.33, HCO3-27, PCO2-48, and PO2- 96. The Urine Specific Gravity is 1.040.

Abnormal Laboratory Findings in the Results

Abnormal lab findings in the blood chemistries include elevated sodium and chloride levels at 147mmol/L and 110 mmol/L, respectively. The normal range for sodium is 135-145 mmol/L, while for chloride is 98-106 mmol/L (Kovesdy, 2017). A high sodium level indicates a decrease in total body water (Kovesdy, 2017). An imbalance in chloride levels indicates dehydration, metabolic acidosis, nephrotic syndrome, renal failure, and diabetes insipidus.

In the ABG results, the pH is low at 7.33, which indicates hydrogen ions deficit. The reference pH range is 7.35-7.45. The patient has a high PCO2 at 48, indicating excess levels of carbonic acid in the blood due to respiratory disorders (Hamilton et al., 2017). The reference range of PCO2 is 35-45 mmHg. The HCO3 is slightly above the normal range of 22-26 mmol/L, indicating high bicarbonate levels in the blood. The reference range of HCO3 is 22-26 mmol/L (Hamilton et al., 2017). In addition, the patient has an increased urine gravity, above the reference range of 1.005-1.025, meaning that there is a high urine concentration from dehydration.

Specific Electrolyte Disturbance 

The electrolyte disturbances present in the patient include hypernatremia and hyperchloremia based on high sodium and chloride levels.

Clinical Manifestations With the Electrolyte Abnormality

Clinical features expected with hypernatremia include cognitive dysfunction, generalized body weakness, and signs of dehydration such as dry mucous membranes, dry skin, abnormal skin turgor, high heart rate, and reduced urine output (Qian, 2019). Manifestations that may occur with hyperchloremia include irregular heart rate, elevated blood pressure, edema, muscle weakness, tingling sensations, confusion, and seizures.

Clinical Manifestations to Monitor If There Is a High Potassium Level

Clinical manifestations that the nurse would assess for in elevated potassium levels include chest pain, difficulties in breathing, nausea, vomiting, muscle weakness, tingling sensations, body weakness, and tall T waves on ECG (Kovesdy, 2017).

Blood Gas Abnormality Seen In the Patient

Respiratory acidosis with metabolic compensation is the blood gas abnormality evident in the patient based on her Arterial Blood Gas results. Respiratory acidosis is diagnosed when there is an excess of carbonic acid when CO2 levels in the blood rise over 45 mm Hg (Hamilton et al., 2017). The pH is below the reference range, indicating acidosis. The PCO2 is above the normal range meaning that the acid-base problem is a respiratory cause (Hamilton et al., 2017). The HCO3 is slightly above the normal range, indicating that the kidneys are compensating for the imbalance through excretion of hydrogen ions and retention of bicarbonate ions to correct the acidosis.

Three Major Mechanisms of pH Regulation

The major pH regulation mechanisms include chemical buffer systems, respiratory and kidney mechanisms. Chemical buffers include bicarbonate acid, phosphate, and plasma proteins (Quade et al., 2021). The bicarbonate buffer system is vital to maintaining acid-base balance in the body because CO2 and HCO3 can be regulated separately. Respiratory mechanisms regulate CO2 through alveolar ventilation in the lungs (Quade et al., 2021). The kidneys regulate Hydrogen ions concentration whereby they excrete the ions to maintain an acid-base balance. Kidneys eliminate non-volatile acids.



Hamilton, P. K., Morgan, N. A., Connolly, G. M., & Maxwell, A. P. (2017). Understanding Acid-Base Disorders. The Ulster medical journal86(3), 161–166.

Kovesdy C. P. (2017). Updates in hyperkalemia: Outcomes and therapeutic strategies. Reviews in endocrine & metabolic disorders18(1), 41–47.

Qian, Q. (2019). Hypernatremia. Clinical journal of the American Society of Nephrology: CJASN14(3), 432–434.

Quade, B. N., Parker, M. D., & Occhipinti, R. (2021). The therapeutic importance of acid-base balance. Biochemical Pharmacology183, 114278.

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