Respiratory - Acid-Base Regulation Midterm Notes PDF

4 1 RESPIRATORY – Acid-Base Regula/on Acid-Base Regula/on Acid-base regula0on refers to the body's ability to maintain a stable pH within the narrow range of 7.35 to 7.45. The body relies on chemical buffers...

4 1 RESPIRATORY – Acid-Base Regula/on Acid-Base Regula/on Acid-base regula0on refers to the body's ability to maintain a stable pH within the narrow range of 7.35 to 7.45. The body relies on chemical buffers, respiratory control, and renal func0on to regulate pH. 1. Most Likely Cause The most likely causes of acid-base imbalances include metabolic or respiratory dysfunc0ons that affect the concentra0on of hydrogen ions (H⁺) in the body. These causes are typically classified as: Acidosis (pH < 7.35): o Respiratory Acidosis: Caused by condi0ons that impair CO₂ exhala0on (e.g., hypoven/la/on, chronic obstruc0ve pulmonary disease (COPD)). o Metabolic Acidosis: Caused by increased produc/on of acids (like in diabe/c ketoacidosis) or loss of bicarbonate (like in diarrhea). Alkalosis (pH > 7.45): o Respiratory Alkalosis: Caused by hyperven/la/on, leading to excessive CO₂ exhala0on (e.g., anxiety, panic aMacks). o Metabolic Alkalosis: Caused by loss of hydrogen ions (like vomi0ng) or increased bicarbonate (like excessive antacid use). 2. Pathophysiology The pathophysiology of acid-base imbalances depends on the nature of the imbalance (acidosis vs. alkalosis) and the system involved (respiratory vs. metabolic). Respiratory Acidosis Cause: Hypoven0la0on causes reten/on of CO₂, which combines with water to form carbonic acid (H₂CO₃), leading to a decrease in pH. Pathophysiology: o CO₂ reten0on increases PaCO₂ (> 45 mmHg), forming more H₂CO₃. o The increase in H₂CO₃ increases H⁺ ions, leading to a decrease in pH (acidosis). o Compensa/on: The kidneys retain bicarbonate (HCO₃⁻) to neutralize the excess H⁺ ions. Respiratory Alkalosis Cause: Hyperven0la0on causes excessive loss of CO₂, reducing the forma0on of H₂CO₃. Pathophysiology: o Decreased PaCO₂ (< 35 mmHg) leads to decreased H₂CO₃. o Fewer H⁺ ions are produced, resul0ng in an increase in pH (alkalosis). o Compensa/on: The kidneys excrete bicarbonate (HCO₃⁻) to decrease pH. Metabolic Acidosis Cause: Accumula0on of non-vola0le acids (like lac/c acid in sepsis) or loss of bicarbonate (like in diarrhea). Pathophysiology:  2 o Increased produc0on of acids or loss of bicarbonate increases H⁺ ion concentra0on, decreasing pH. o Compensa/on: The lungs compensate by increasing respiratory rate (hyperven0la0on) to "blow off" CO₂, reducing H₂CO₃. Metabolic Alkalosis Cause: Loss of hydrogen ions (like vomi0ng) or excess bicarbonate (from excessive use of antacids). Pathophysiology: o Loss of H⁺ ions (from gastric secre0ons) increases pH. o Excess bicarbonate increases pH by neutralizing H⁺. o Compensa/on: The lungs reduce respiratory rate (hypoven0la0on) to retain CO₂, which increases H₂CO₃. 3. Disease Transmission Transmission: o Not transmissible. Acid-base imbalances are not infec0ous or communicable diseases【105:1†source】. o These condi0ons result from metabolic, respiratory, or renal dysfunc/ons, as well as environmental factors (e.g., drug overdose or exposure to toxins). 4. Risk Factors Risk factors for acid-base imbalances include chronic diseases, environmental factors, and acute condi/ons. Risk Factors for Acidosis Respiratory Acidosis: o Chronic Lung Disease: COPD, emphysema, or chronic bronchi0s can reduce lung ven0la0on. o Neurological Impairment: Damage to the respiratory center in the brainstem reduces ven0la0on. o Overdose of CNS Depressants: Drugs like opioids or seda0ves reduce breathing rate, causing CO₂ reten0on. o Obesity Hypoven/la/on Syndrome (OHS): Obesity restricts lung expansion, impairing ven0la0on. Metabolic Acidosis: o Diabe/c Ketoacidosis (DKA): Results from increased produc0on of ketone bodies. o Lac/c Acidosis: Seen in condi0ons of hypoxia, such as sepsis or severe anemia o Renal Failure: The kidneys are unable to excrete H⁺, leading to acid accumula0on. o Diarrhea: Causes loss of bicarbonate, leading to acidosis. Risk Factors for Alkalosis Respiratory Alkalosis: o Anxiety and Panic AZacks: Hyperven0la0on causes excessive exhala0on of CO₂.  3 o Pain: Can increase breathing rate, leading to hyperven0la0on. o Sepsis and Fever: Increase the metabolic rate and s0mulate the respiratory center to cause hyperven0la0on. o High Al/tude: Decreased oxygen in the air s0mulates the respiratory center to increase ven0la0on. Metabolic Alkalosis: o Vomi/ng: Causes loss of HCl (hydrogen chloride) from the stomach, leading to alkalosis. o Nasogastric Suc/on: Removal of gastric contents removes H⁺ ions, leading to alkalosis. o Excessive Use of Antacids: Leads to excess bicarbonate in the body. o Diure/c Use: Increases renal loss of H⁺, par0cularly with loop diure0cs and thiazides. Summary Table Criteria Acid-Base Regula/on Acidosis: Hypoven0la0on, DKA, lac0c acidosis, renal failure, diarrhea. Most Likely Alkalosis: Hyperven0la0on, vomi0ng, nasogastric suc0on, diure0c use, Cause excessive antacids. Respiratory Acidosis: ↑CO₂ → ↑H₂CO₃ → ↑H⁺ → ↓pH. Metabolic Acidosis: Pathophysiology ↑H⁺ or ↓HCO₃⁻. Respiratory Alkalosis: ↓CO₂ → ↓H₂CO₃ → ↓H⁺ → ↑pH. Metabolic Alkalosis: ↓H⁺ or ↑HCO₃⁻. Transmission Not transmissible. These condi0ons are non-infec0ous【105:1†source】. Acidosis: COPD, DKA, renal failure, diarrhea, opioid overdose. Alkalosis: Risk Factors Anxiety, pain, vomi0ng, diure0cs, excessive antacids.