Acid-Base Balance and Homeostasis

• College NURS 1250 Nursing Care of Adults II Exam 2 covers the concept of acid-base balance.

Overview of Acid-Base

• Acids produce H+, lower pH, and release protons, with examples including Na+, K+, Ca++, and Mg++.
• Bases accept H+, raise pH, and involve electrons, with examples including HCO3- and Cl-.
• The pH scale ranges from 0 to 14, where 0-6 is acidic, 7 is neutral, and 8-14 is alkaline.

Common Acids and Bases

• Battery acid has a pH of 0; Stomach acid has a pH of 1; Lemon has a pH of 2; Vinegar a pH of 3; Tomato a pH of 4.
• Coffee has a pH of 5; Milk has a pH of 6; Pure water a pH of 7; Blood has a pH of 8; Baking soda pH is 9.
• Antacids have a pH of 10; Ammonia has a pH of 11; Soap has a pH of 12; bleach has a pH of 13 and drain cleaner has a pH of 14.

Role of Acids and Bases

• They help maintain pH levels.
• They maintain stable concentrations of H+.
• They provide neutral environments.
• They compensate for specific imbalances.

Importance of Balance

• Necessary for homeostasis, which is essential for all cellular metabolism.
• Homeostasis is a balancing act.

Hydrogen Ions

• Homeostasis of H+ concentration in body fluids: Increased H+ results in acidity and decreased H+ makes it alkaline.
• Hydrogen ion concentration is expressed as pH: Increased H+ lowers pH and decreased H+ raises pH.

Formation of Acids and Bases

• Carbon dioxide (CO2) plus water (H2O) forms carbonic acid (H2CO3).
• Carbonic acid dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-).
• H2CO3 forms when CO2 dissolves in H2O and dissociates to release H+ and HCO3-.
• Acids and bases form through dissociation reactions.

Acidosis or Alkalosis

• Arterial blood pH indicates acidosis or alkalosis; normal pH range is 7.35-7.45.
• Acidosis is below 7.35, and alkalosis is above 7.45.
• The survival range on the pH scale is between 6.8 and 8.0.

Arterial Blood Gas (ABG) Values

• Normal pH is 7.35-7.45; Acidosis is indicated by a pH lower than 7.35; Alkalosis by pH higher than 7.45.
• Normal PaCO2 is 35-45; Acidosis indicated by PaCO2 higher than 45; Alkalosis by PaCO2 lower than 35.
• Normal HCO3- is 22-26; Acidosis is indicated by HCO3- lower than 22; Alkalosis by HCO3- higher than 26.
• Normal PaO2 is 80-100; PaO2 below 80 indicates hypoxemia.

Importance of ABG Values

• Provides valuable information about the body's ability to regulate pH.
• Identifies the patient's acid-base status.
• Reveals underlying cause of acid base imbalance.
• Gives information on a patient’s overall oxygen status.

Detection of Imbalances

• Hydrogen (H+) and bicarbonate (HCO3-) ions retained or excreted by the kidneys can be indicators of imbalance.
• Carbon dioxide (CO2) which is retained or expelled from the lungs can be indicators of imbalance.

Regulatory System

• The regulatory system includes the following components: the bicarbonate buffer system, phosphate buffer system, and protein buffer system.
• The first line of defense against pH shift is a chemical buffer system.
• The second line of defense against pH shift is physiological buffers.
• Respiratory mechanism (CO2 excretion) and renal mechanism (H+ excretion) are part of the regulatory system.

Compensation

• Compensation occurs when one system assists because another is impaired.
• Lungs regulate acid-base balance to respond to a metabolic disorder.
• Kidneys regulate acid base balance to to respond to a respiratory disorder.
• Partial compensation means pH remains abnormal, while complete compensation means pH returns to normal.

Acid-Base Disorders

• Acid-base disorders occur when the body's pH varies from the normal range.
• Acid-base disorders are influenced by H+: Decreased H+ leads to increased pH (alkaline) while increased H+ leads to decreased pH (acidic).
• Acid-base disorders are classified as respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis.

Respiratory Acidosis

• It is the result of decreased ventilation causing hypoventilation.
• Increased PaCO2 causes hypercapnia.
• Increased H2CO3 forms from the reaction of CO2 dissolved in H2O.
• H+ and HCO3- are released.
• Results in a decreased pH.

Respiratory Acidosis Etiology

• Respiratory depression, obstruction, or chronic respiratory problems can lead to respiratory acidosis.
• The kidneys compensate with increased absorption of HCO3- and excretion of H+ in urine.

Respiratory Acidosis Cues

• Respiratory cues include rapid and shallow respirations that progress to shallow and depressed breathing.
• Neurological cues include dizziness, disorientation, headache, and coma.
• Cardiovascular cues include arrhythmias and hypotension.
• Neuromuscular cues include muscle twitching, progressing to seizures.

Respiratory Acidosis Actions

• Maintain a patent airway.
• Administer oxygen cautiously.
• Monitor vital signs and respiratory rate and depth.
• Monitor ABG levels, serum potassium levels and administer sedatives cautiously.
• Reinforce patient teachings.

Respiratory Alkalosis

• Increased ventilation (hyperventilation) results in decreased PaCO2, causing hypocapnia.
• Decreased H2CO3 and low CO2 concentration leads to increased arterial pH levels.

Respiratory Alkalosis Etiology

• Can be caused by any factor that significantly contributes to hyperventilation.
• The kidneys compensate by increasing the absorption of H+ and increasing the excretion of HCO3- in the urine.

Respiratory Alkalosis Cues

• Respiratory cues include periods of apnea and hyperventilation.
• Neurologic cues include lightheadedness, confusion, and lethargy.
• Cardiovascular cues include tachycardia and arrhythmias.
• Neuromuscular cues include tingling of extremities, hyperreflexia, tetany, and seizures.
• Gastrointestinal cues include epigastric pain, nausea, and vomiting.

Respiratory Alkalosis Actions

• Instruct the patient to breathe slowly and less deeply and monitor their vital signs and respiratory rhythm.
• Monitor ABG levels and serum potassium level, while cautiously administering sedatives.
• Reinforced patient teachings.
• Interventions include pursed-lip breathing and breathing into a paper bag to increase CO2 levels.

Metabolic Acidosis

• A gain of acid or the inability to excrete acid
• There is Bicarbonate deficit.
• Decreased pH due to excess H+.

Metabolic Acidosis Etiology

• DKA, renal failure, diarrhea, salicylate poisoning and starvation
• Respiratory compensation includes increased elimination of CO2 to raise pH.

Metabolic Acidosis Cues

• Respiratory cues include Kussmaul breathing along with or fruity breath in DKA.

• Neurologic cues include dull headache, lethargy, confusion, and coma.

• Cardiovascular cues include arrhythmias and hypotension.

• Neuromuscular cues include tingling and numbness in extremities.

• Gastrointestinal cues include abdominal pain, anorexia, nausea, and vomiting.

Actions for Metabolic Acidosis

• Monitor neurologic status and vital signs, including respiratory rate and depth.
• Position the patient to facilitate breathing and administer oxygen to correct lactic acidosis.
• Monitor ABG levels and HCO3- and K+ levels.
• Administer IVF containing lactate as ordered.
• Administer insulin and NS to correct hyperglycemia.
• Administer NaHCO3 cautiously.
• Institute cardiac monitoring for patients with increased K+.
• Reinforced patient teachings.

Metabolic Alkalosis

• Loss of strong acid
• HCO3- excess
• Increased pH due to decrease in H+.

Metabolic Alkalosis Etiology

• Nasogastric suctioning, diuretic therapy, and prolonged vomiting are factors.
• Respiratory compensation includes decreased ventilation to retain CO2.

Metabolic Alkalosis Cues

• Respiratory cues include slow, shallow breathing.
• Neurologic cues include irritability, disorientation, and belligerence.
• Cardiovascular cues include dysrhythmias.
• Neuromuscular cues include tingling, muscle cramps, and tetany.
• Gastrointestinal cues include anorexia, nausea, and vomiting.

Actions for Metabolic Alkalosis

• Monitor vital signs, asses neurological status, and monitor ABG levels.
• Provide IVF and electrolyte supplements as ordered.
• Monitor patients at risk for metabolic alkalosis and Reinforced patient teachings.

Acid-Base Pneumonic (ROME)

• ROME: Respiratory Opposite, Metabolic Equal.
• In respiratory imbalances, pH and PaCO2 move in opposite directions.
• In metabolic imbalances, pH and HCO3- move in the same direction.

Interpret ABGs

• Respiratory Acidosis shows pH is decreased with increased PaCO2; HCO3 is normal
• Respiratory Alkalosis shows pH is increased with decreased PaCO2; HCO3 is normal.
• Metabolic Acidosis shows pH is decreased with normal PaCO2 and a decreased HCO3-.
• Metabolic Alkalosis shows pH is increased with normal PaCO2 and increased HCO3-.

Pulmonary and Renal Compensation

• Respiratory acidosis involves eliminating excess CO2.
• Respiratory alkalosis involves retaining CO2.
• Metabolic acidosis involves conserving HCO3- and eliminating excess H+.
• Metabolic alkalosis conserves H+ and eliminates excess HCO3-.

Basis for Compensation

• Uncompensated: pH is abnormal with no change in PaCO2 or HCO3-.
• Partially Compensated: pH is abnormal with changes in PaCO2 or and HCO3, following shift.
• Compensated: pH is normal with changes in PaCO2 and HCO3, following shift.

Compensation: pH Tells the Tale

• Partially compensated respiratory acidosis: pH 7.33, PaCO2 46, HCO3- 27.
• Fully compensated respiratory alkalosis: pH 7.43, PaCO2 30, HCO3- 20.
• Fully compensated metabolic acidosis: pH 7.37, PaCO2 28, HCO3- 18.
• Partially compensated metabolic alkalosis: pH 7.48, PaCO2 47, HCO3- 30.

Battle For Homeostasis

• Assess, intervene, stay curious, and think critically.

Explore acid-base balance, homeostasis, and the body's responses to imbalances. Questions cover the roles of acids, bases, kidneys, and lungs in maintaining pH levels. Arterial blood gas results, compensation mechanisms, and conditions like COPD and diabetic ketoacidosis are also addressed.