Pathophysiology Acid-Base Lecture Notes
Pathophysiology Acid-Base Lecture Notes NUR 305
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This 0 page Study Guide was uploaded by Shelby Stephens on Tuesday November 17, 2015. The Study Guide belongs to NUR 305 at University of Alabama - Tuscaloosa taught by Owings in Fall 2015. Since its upload, it has received 56 views. For similar materials see Pathophysiology in Nursing and Health Sciences at University of Alabama - Tuscaloosa.
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Date Created: 11/17/15
Acid Base Balance Measured by pH 0 Normal serum pH 735745 Body uids kidneys and lungs maintain our acidbase balance Subtle changes can cause serious effects pH Regulation pH re ects hydrogen concentrations Hydrogen is an acid The more hydrogen the lower the pH Acids are byproducts of metabolism Volatile acids Volatile gases Nonvolatile gases 0 3 systems work to maintain acidbase balance the buffers respiratory system and renal system Buffers Chemicals that combine with an acid or base to change pH Immediate reaction to counteract pH variations until compensation is initiated 4 major buffer mechanisms the bicarbonatecarbonic acid system the phosphate system the hemoglobin system and the protein system Bicarbonate Carbonic Acid System Most signi cant in the extracellular uid Carbonic acid and bicarbonate are the key players Carbonic acid forms from carbon dioxide reacting with water Carbonic anhydrase causes carbonic acid to separate into hydrogen and bicarbonate Carbonic anhydrase in the lungs allows for carbon dioxide excretion and in the kidneys allows for hydrogen excretion CO2 H20 Lungs 4 7 H2003 w H quot H005 Kidneys Phosphate System Similar to the bicarbonatecarbonic acid system Phosphates are in high concentrations in the intracellular uid Some phosphates act as weak acids and some act as weak bases This system primarily occurs in the kidneys by accepting or donating hydrogen Hemoglobin System Primarily occurs in the capillaries Acidity and hypoxia causes hemoglobin to release the oxygen Hemoglobin then becomes a weaker acid taking up extra hydrogen Binding with oxygen makes hemoglobin more prone to release hydrogen Hydrogen reacts with bicarbonate to form carbonic acid which is converted to carbon dioxide and released into the alveoli Protein System Most abundant buffering system Proteins can act as an acid or base by binding to or releasing hydrogen Occurs in the intracellular and extracellular spaces Hydrogen and carbon dioxide diffuse across the cell membrane to bind with protein inside the cell Albumin and plasma are the primary buffers in the intravascular space Potassium Potassium and hydrogen move interchangeably in and out of the cell to balance pH With extracellular excess hydrogen moves inside the cell for buffering and in exchange potassium moves out Potassium imbalances can lead to pH imbalances Respiratory Regulation Alters carbon dioxide excretion Speeding up respirations will excrete more carbon dioxide decreasing acidity Slowing down respirations will excrete less carbon dioxide increasing acidity Uses chemoreceptors Responds quickly but is shortlived Renal Regulation Alters the excretion or retention of hydrogen or bicarbonate More effective by permanently removing hydrogen Responds slowly but longer lasting Compensation The body never overcompensates The cause of the imbalance often determines the compensatory change If the problem causing the pH imbalance originates in the lungs the kidneys initiates efforts to correct it If the problem causing the pH imbalance originates outside the lungs the lungs initiate efforts to correct it Metabolic Acidosis Results from a de ciency of bicarbonate or an excess of hydrogen Causes Bicarbonate de cit intestinal and renal losses Acid excess tissue hypoxia resulting in lactic acid accumulation ketoacidosis drugs toxins and renal retention Diagnosis History Physical examination Labs Arterial blood gases Blood chemistry Complete blood count Manifestations Appear as regulatory systems fail to maintain pH within normal range Occur in combination with manifestations of underlying condition Headache Malaise Weakness Fatigue Lethargy Coma Warm and ushed skin Nausea vomiting Anorexia Hypotension dysrhythmias Shock Kussmaul s respirations Hyperkalemia Treatment Identifying and treating the causative condition Strategies to correct the acidosis include Intravenous bicarbonate correction of electrolyte disturbances improving oxygenation and insulin Anion Gap Helpful in determining the cause of metabolic acidosis Identi es the anions that are not measured Conditions that cause excess acid will increase the anion gap otherwise the anion gap is normal The sum of cations should be approximately equal to the sum of anions in the extracellular uid Sodium is the most plentiful cation in the extracellular uid while bicarbonate and chloride are the most abundant anions To determine the anion gap the bicarbonate and chloride results are added together and subtracted from the sodium Normal anion gap is 6 9 mEqL Metabolic Alkalosis Results from excess bicarbonate or de cient acid or both Causes Excess bicarbonate excessive antacid use use of bicarbonatecontaining uids and hypochloremia De cient acid gastrointestinal loss hypokalemia renal loss hypovolemia and hyperaldosteronism Manifestations Appear as regulatory systems fail to maintain pH within normal range Occur in combination with manifestations of underlying condition Mental confusion Hyperactive re exes Paresthesia Tetany Seizures Respiratory depression Dysrhythmias Coma Diagnosis History Physical examination Arterial blood gases Blood chemistry Complete blood count Treatment Identifying and treating the causative condition Strategies to correct the alkalosis include adequate hydration correcting electrolyte disturbances Diamox arginine hydrochloride and administering a weak hydrochloric acid solution Respiratory Acidosis Results from carbon dioxide retention which increases carbonic acid Caused by conditions that result in hypoventilation or decreased gas exchange Acute asthma exacerbations chronic obstructive pulmonary disease airway obstructions pulmonary edema pneumonia drug overdose respiratory failure and central nervous system depression Manifestations Appear as regulatory systems fail to maintain pH within normal range Occur in combination with manifestations of underlying condition Include headache Blurred vision Tremors Muscle twitching Vertigo Irritability disorientation lethargy coma Tachycardia leading to bradycardia blood pressure uctuations Diaphoresis Diagnosis History Physical examination Arterial blood gases Blood chemistry Complete blood count Chest X ray Treatment Oxygen therapy Mechanical ventilation Positioning the patient for optimum ventilation Bronchial hygiene measures Bronchodilators Manage causative conditions Respiratory Alkalosis Results from excess exhalation of carbon dioxide which leads to carbonic acid de cits Caused by conditions that result in hyperventilation Acute anxiety pain fever hypoxia gramnegative septicemia aspirin overdose excessive mechanical ventilation and hyper metabolic states Manifestations Appear as regulatory systems fail to maintain pH within normal range Occur in combination with manifestations of underlying condition Paresthesia Dizziness Vertigo Syncope Muscle irritability and twitching Tetany Inability to concentrate Seizures Tachycardia dysrhythmias Dry mouth Anxiety excessive diaphoresis Coma Diagnosis History physical examination arterial blood gases blood chemistry complete blood count and chest X ray Treatment Manage underlying conditions breath into a paper bag mechanical ventilation and anxiety reduction strategies Mixed Disorders Respiratory and metabolic disorders resulting in an acidotic or alkalotic state Both the respiratory and renal systems demonstrate an imbalance of acid or base Causes pulmonary edema aspirin overdose fever and vomiting Critical and complex condition Vomiting metaboiic aiikalosis History of diabetes metaboiic acidosis History smokingCOPD respiratory acidosis History of liver diseaseErespiratory alkalosis Recent binge drinking metabolic acidosis Diarrhea metaboiic acidosis TachypneaErespiratory alkaiosis HypotensionErnetabolic acidosis Aspirin ingestion mixed respiratory alkailosis and metabolic acidosis INI quotl xooouoxowsem Arterial Blood Gas Interpretation pH serum hydrogen concentration Indicates acidbase status PaCOZ partial pressure of carbon dioxide Indicates the adequacy of pulmonary ventilation HCO3 bicarbonate Indicates the activity in the kidneys to retain or excrete bicarbonate PaOz partial pressure of oxygen Indicates serum oxygen concentration Base excessde cit Indicates serum buffer concentration particularly bicarbonate Positive values indicate an excess of base or a de cit of acid Negative values indicate a de cit of base or an excess of acid ROME method Look at pH Draw arrows high or low Next look at C02 Draw arrow for high low or normal If C02 is normal then go to HCO3 and draw and arrow if high low or normal Arrows in opposite direction respiratory Respiratory opposite Arrows in same direction metabolic Metabolic equal ROME ACID ENEE rwJEMONlC Raepiratciry Dpp eita Fall IT F533 likalaaia PH FCUE aigl aie Manama Equal PH l lC aT lkalaeie Ile i H i asideslie pH of Blood The pH of blood indicates the concentration of H Normal pH 735 745 Less than 735 is acidosis Greater than 745 is alkalosis Regulation of pH PCOZ Normal range 35 45 mmHg Partial pressure exerted by carbon dioxide Principle substance affecting acid Carbon dioxide combines with water HCO3 Normal range 2226 mmolL Bicarbonate or HC03 Principle alkaline substance Slowly binds with free H making H2C03
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