Fluid and Electrolyte Imbalance Lecture 3 12212021 1
Fluid and Electrolyte Imbalance Lecture 3 12/21/2021 1
Acid Base Disturbance • Plasma p. H is an indicator of hydrogen ions concentration • The increase in hydrogen in the blood make it acid while the lower hydrogen make it alkaline • Normal plasma p. H is 7. 35 -7. 45 • Lower p. H means more acidity • There is 3 important factors that control the p. H of blood hydrogen ion H+, bicarbonate ions HCO 3 - and carbon dioxide CO 2. • H+ , HCO 3 - and CO 2 are routinely measured in Arterial Blood Gas sample (ABG) • The more HCO 3 - in the blood the more the alkalinity( normal value 22 -26 m. Eq/L) • The more CO 2 the more the acidity (normal value 35 -45 mm. Hg) 12/21/2021 2
• Kidney and lung has the primary role in maintaining p. H in the blood • Kidney is responsible for the 24 hrs regulation of p. H while the lung act mainly in the emergency situation • Kidney regulate p. H directly through bicarbonate and hydrogen ions. • When the blood is acidic the kidney produce more bicarbonate and increase excretion of hydrogen ions. The opposite happens in case of alkalosis • The lung helps in mainatinence of p. H through CO 2 control • When the blood is acidic the lung increase the rate and depth of breathing which lead to wash off CO 2. • When the blood is alkaline the lung decrease the rate and depth of breathing which entails more CO 2 retintion in the blood • Change in bicarbonate concentration in the blood reflect a metabolic disorder while the change in CO 2 reflects a respiratory disorder. Change in both reflect mixed metabolic and respira. tory disorder 12/21/2021 3
Metabolic Acidosis • A clinical disturbance that is characterized by low p. H ( less than 7. 35) low bicarbonate ( less than 22 m. Eq/L and low hydrogen concentration. Clinical manifestations • Increase rate and depth of breathing • Peripheral vasodilation which lead to hypotension • Decrease cardiac out put • Neurologic sign such as headache confusion Causes: renal failure, loss of bicarbonate as in diarrhea, vomiting , lower intestinal fistula , excessive administration of chloride, hyperkalemia 12/21/2021 4
Metabolic Acidosis Medical management • Adminsiter bicarbonate when p. H below 7. 1 • Ringer lactate ( sodium lactate): metabolized into sodium bicarbonate inside the body • correct hyperkalemia: Potassium move from inside the cell to the blood in exchange for hydrogen ions which increase acidity of the blood. 12/21/2021 5
Metabolic Alkalosis • Clinical disturbance characterized by high p. H ( higher than 7. 45) and high bicarbonate (higher than 26 m. Eq/L) • Causes • The most common cause is vomiting or nasogastric tube suction ( gastric secretion is p. H is 1 to 3 and rich in hydrogen and chloride). • Condition of hypokalemia 12/21/2021 6
Metabolic Alkalosis Clinical manifestations • Usually related to decrease calcium ionization( calcium need acid environment to be chemically active). • Symptoms of hypocalcaemia develop such as tingling of fingers, respiratory depression Management • Administration of chloride( increase bicarbonate excretion) • Administer potassium in case of hypokalemia 12/21/2021 7
Respiratory acidosis • A clinical disturbance charcterized by low p. H( less than 7. 35), and CO 2 higher than 45 mm. Hg. Causes All condition that increase CO 2 in the blood such as respiratory diseases atelectasis, pneumonia…. . ) 12/21/2021 8
Respiratory acidosis Clinical manifestations • Increase rate and depth of breathing • Signs of vasodilation in brain and peripheral as a result of increase CO 2 such as increase in intracranial pressure (ICP) • Cardiac arrhythmia • Hyperkalemia ( potassium increase as exchange with hydrogen ions) Medical management • Manage respiratory disease, improve oxygenation 12/21/2021 9
Respiratory alkalosis • Clinical disturbance characterized by high p. H greater than 7. 45 and CO 2 less than 35 mm. Hg Causes • Main cause is Hyperventilation which cause excessive blow off ( wash off ) for CO 2 • Other causes include salicylate toxicity ( aspirin) Clinical manifestations Signs of decrease cerebral blood flow such as inability to concentrate, cardiac arrhythmia 12/21/2021 10
Respiratory alkalosis Medical management • Treatment of the underlying cause 12/21/2021 11
- Slides: 11