Acid-Base Imbalance Notes

Definition: The regulation of arterial blood gas (ABG) pH between 7.35 to 7.45.
Mechanism: Achieved through the regulation of hydrogen ions (H+) production and elimination.
Importance of maintaining proper acid-base balance for physiological functions.

Function of Lungs:
  - Breathe in oxygen (O2) and exhale carbon dioxide (CO2).
  - CO2 as an Acid:
    - CO2 is considered an acid in the blood.
    - Retaining CO2 increases acidity, resulting in respiratory acidosis.
    - Exhaling CO2 decreases acidity, potentially leading to respiratory alkalosis.
Clinical Examples:
- Breathing too fast (hyperventilation) can lead to decreased CO2 levels and alkalosis.
- Breathing too slowly (hypoventilation) can lead to increased CO2 levels and acidosis.

Multiple Organs Involvement:
- Gastrointestinal (GI) tract: Differences between upper and lower GI.
Clinical Examples:
- Diarrhea: Can result in metabolic acidosis.
- Vomiting: Can lead to metabolic alkalosis.
Renal Functions:
  - Producing or eliminating bicarbonate (HCO3) affects pH.
  - Creating large amounts of bicarbonate can lead to alkalosis.
  - Not producing enough bicarbonate can contribute to acidosis.

pH: Normal range is 7.35 - 7.45.
CO2: Normal range is 35 - 45 mmHg.
PaCO2: Normal range is 35 - 45 mmHg (estimates CO2 exchange).
PaO2: Normal range is 80 - 100 mmHg.
HCO3: Normal range is 22 - 28 mEq/L.
O2 Saturation: Normal range is 95 - 100%.
Examples of Test Results:
  - pH = 7.38, CO2 = 36, HCO3 = 24
  - pH = 7.36, CO2 = 40, HCO3 = 26
  - pH = 7.37, CO2 = 42, HCO3 = 27

Mechanism: Balance of CO2 levels directly affects acidity.
Respiratory Acidosis:
  - Characteristics: Low pH, high CO2.
  - Causes:
    - Conditions that cause CO2 retention (e.g., respiratory depression from anesthetics, narcotics, muscle weakness, airway obstruction).
Respiratory Alkalosis:
  - Characteristics: High pH, low CO2.
  - Causes:
    - Conditions that result in CO2 loss (e.g., hyperventilation due to fear, anxiety, pain, mechanical ventilation, salicylate toxicity, high altitude, early pulmonary disorders).

Mechanism: Primarily regulated in the kidneys.
Metabolic Acidosis:
  - Characteristics: Increased acid production or decreased acid elimination.
  - Causes:
    - Diabetic ketoacidosis (DKA), starvation, heavy exercise (lactic acidosis), seizures, fever, hypoxia, salicylate intoxication, kidney failure.
Metabolic Alkalosis:
  - Characteristics: Resulting from excess base or loss of acid.
  - Causes:
    - Excess antacid use, total parenteral nutrition (TPN), blood transfusions, bicarbonate administration, excessive vomiting, NG suctioning, diuretic use, laxative overuse.
Mechanism for Increasing pH:
- Kidneys decrease excretion of bicarbonate (HCO3) and decrease the absorption of hydrogen ions.

Assessment Features:
  - Altered level of consciousness (LOC), which may arise from encephalopathy or cerebral edema, head trauma.
  - Respiratory rate is low and shallower.
  - Skin may appear pale to cyanotic and dry.
Treatment Approaches:
  - Pulmonary hygiene: Promote effective breathing techniques (deep breathing).
  - Oxygen therapy.
  - Pharmacologic interventions: Mycolytics, bronchodilators.
  - Monitoring: Assess breath sounds, check for good airflow, and evaluate for accessory muscle use and retractions.
Observational Indicators:
- Asterixis: Inability to maintain posture in parts of the body.

Assessment Features:
- Hyperventilation is noticeable.
Treatment Approaches:
  - Anti-anxiety medications may be used.
  - If the patient is on a ventilator, the respiratory rate may need adjustment.
  - In cases of aspirin overdose (ASA OD), immediate interventions must be instituted.

Assessment Features:
- Kussmaul's respirations: Deep and rapid, involuntary, occurring as a compensation for metabolic acidosis.
- Warm, flushed, and dry skin may be present.
Treatment Approaches:
  - Hydration: Hypotonic intravenous fluids.
  - Pharmacologic intervention: Insulin for DKA, anti-diarrheal medications for diarrhea-related cases.
  - Caution: Administering bicarbonate can be complicated; consult nephrology for renal involvement in acidosis.
  - Considerations for muscle weakness: Monitor respiratory efforts and adjust doses of medications as necessary for those on diuretics.

Assessment Features:
- May exhibit decreased respiratory effort due to muscle weakness.
- Confusion and lethargy could also be present.
Treatment Approaches:
  - Reducing or stopping NG suction if it is contributing significantly to alkalosis.
  - Antiemetic medications may be used for vomiting.
  - Advising the cessation of excess antacid use and decreased laxative consumption can be beneficial.