Acid-Base Imbalances: Respiratory and Metabolic Acidosis and Alkalosis

Vocabulary flashcards covering the pathophysiology, clinical manifestations, lab values, and causes of respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis.

Respiratory Acidosis

An acid-base disturbance characterized by retention of $CO_2$ by the lungs, resulting in a $pH < 7.35$ and an elevated $PCO_2$ ($> 45\,mmHg$).

Causes of Respiratory Acidosis

Respiratory depression (from anesthesia, overdose, or increased ICP), airway obstruction, and decreased alveolar-capillary diffusion (due to pneumonia, COPD, ARDS, or PE).

Clinical Manifestations of Respiratory Acidosis

Hypoventilation causing hypoxia, rapid shallow respirations, decreased BP, pale to cyanotic skin/mucosa, headache, hyperkalemia, dysrhythmias, drowsiness, dizziness, disorientation, muscle weakness, and hyperreflexia.

Respiratory Alkalosis

An acid-base disturbance marked by increased loss of $CO_2$ from the lungs, presenting with an elevated $pH > 7.45$ and a decreased $PCO_2$ ($< 35\,mmHg$).

Causes of Respiratory Alkalosis

Hyperventilation caused by anxiety, fear, or pulmonary embolism (PE), as well as mechanical ventilation.

Clinical Manifestations of Respiratory Alkalosis

Hyperventilation in rate and depth, tachycardia, decreased or normal BP, hypokalemia, numbness and tingling of extremities, hyperreflexia, muscle cramping, seizures, increased anxiety, and irritability.

Metabolic Acidosis

A state stemming from a decreased ability of the kidneys to excrete acid or conserve base, defined by a $pH < 7.35$ and reduced $HCO_3$ ($< 22\,mEq/L$).

Causes of Metabolic Acidosis

Diabetic ketoacidosis (DKA), severe diarrhea, renal failure, and shock.

Clinical Manifestations of Metabolic Acidosis

Headache, decreased BP, hyperkalemia, muscle twitching, warm flushed skin caused by vasodilation, nausea, vomiting, diarrhea, changes in LOC (confusion, increased drowsiness), and Kussmaul respirations.

Kussmaul Respirations

Compensatory hyperventilation observed in metabolic acidosis to eliminate excess acid by blowing off carbon dioxide.

Metabolic Alkalosis

An acid-base disorder resulting from decreased acid or increased base, presenting with an elevated $pH > 7.45$ and increased $HCO_3$.

Causes of Metabolic Alkalosis

Increased $HCO_3$ (from antacids or administration of sodium bicarbonate) and loss of $H^+$ (from NG suctioning, prolonged vomiting, or hypercortisolism).

Clinical Manifestations of Metabolic Alkalosis

Confusion, dysrhythmias (tachycardia secondary to decreased $K^+$), compensatory hypoventilation, dizziness, irritability, nausea, vomiting, diarrhea, anxiety, seizures, and tremors, muscle cramps, or tingling of fingers and toes due to decreased serum $Ca^{2+}$.