Patho 6

Overview of Acid-Base Imbalances

• Introduction to Acid-Base Imbalances

• Discusses the importance of understanding fluid and electrolytes.

• Introduces the concept of acid-base imbalances, specifically in relation to bicarb and carbon dioxide.

Arterial Blood Gas (ABG) Sampling

• Purpose of ABG Sampling

• Arterial blood samples provide information about respiratory function.

• Veins contain blood already influenced by tissue perfusion; arterial samples are undisturbed.

• ABG gives the best picture of gas exchange in the lungs.

• Key Values to Monitor

• pH: Normal range is 7.35 to 7.45.

• CO2: Ranges from 35 to 45 mmHg.

• Bicarb: Ranges from 22 to 26 mEq/L.

• The "PA" prefix denotes partial pressures in arterial blood.

Identifying Acid-Base Imbalances

• Utilizing ABG Values

• These values help identify acidosis or alkalosis and determine if respiratory or metabolic causes are involved.

• Normal partial pressure of oxygen for healthy individuals is 80 to 100 mmHg.

• Oxygen saturation levels should be between 94% to 100%.

• Significance of Additional ABG Parameters

• ABG assessments can indicate how well the lungs oxygenate blood.

• Clinical context is crucial; symptoms may predict ABG results.

Clinical Context in ABG Interpretation

• Example of Clinical Context

• A patient with drug overdose and respiratory depression is likely to have respiratory acidosis, as evidenced by their clinical condition before ABG results.

• Diabetes patients breathing rapidly may indicate lactic acidosis, suggesting potential acid-base imbalance.

Trending ABG Results

• Serial Measurements

• Tracking ABG results over time is essential for observing changes in patient status.

• Allows assessment of whether the patient's pH is improving or deteriorating.

Simplified Understanding of Acid-Base Disorders

• Focus on foundational concepts rather than complex mixed disorders.

• Importance of checking lab results consistently to update providers and nurses.

Acidosis and Its Causes

• Definition of Acidosis

• Acidosis occurs when pH is too low, indicating high hydrogen ion concentration.

• Common causes include shock leading to anaerobic metabolism producing lactic acid.

• Implications of Low Bicarbonate

• A low bicarbonate level indicates metabolic acidosis, where bicarbonate is consumed to buffer excess acid.

Compensation Mechanisms

• Body Compensation for Metabolic Acidosis

• The lungs compensate by increasing respiration to decrease CO2 levels, helping to restore pH balance.

• Causes of metabolic acidosis often involve tissue hypoperfusion, leading to lactic acid production.

Diabetic Ketoacidosis (DKA)

• Pathophysiology of DKA

• Occurs when diabetic patients shift to fat metabolism due to glucose unavailability.

• Ketones produced are non-volatile acids leading to metabolic acidosis.

• Clinical implications of DKA: Low bicarbonate levels, respiratory compensation by blowing off CO2 to restore pH.

Acidosis Due to Gastrointestinal Losses

• Difference Between Fluid Loss Locations

• Diarrhea leads to acidosis due to bicarbonate loss; vomiting leads to alkalosis due to acid loss.

Alkalosis Overview

• Definition and Causes of Alkalosis

• Alkalosis characterized by high pH and may follow base excess.

• Can be caused by diuretics leading to excessive hydrogen loss, vomiting, and certain medications or treatments.

Compensation for Alkalosis

• Body's Compensation Mechanisms

• For metabolic alkalosis, kidneys may excrete more bicarbonate, leading to respiratory adjustment (e.g., decreased respiratory rate).

Respiratory Acidosis and Alkalosis

• Respiratory Acidosis

• Results from high CO2 due to hypoventilation (e.g., lung disease).

• The body compensates by kidneys holding onto bicarbonate.

• Respiratory Alkalosis

• Results from low CO2 due to hyperventilation (e.g., anxiety, pregnancy).

• Kidneys compensate by excreting bicarbonate.

Final Notes: Recognizing and Understanding the Clinical Context

• Understanding the relationship between acidosis and respiratory/metabolic functions is paramount in clinical settings.

• Emphasis on the importance of potassium-hydrogen transporters in managing acidosis and maintaining electrolyte balance.