Acid Base Imbalance Reviewer

ACID BASE IMBALANCE Acid-Base Regulation     Buffers Buffers : solutions that can resist changes in pH, are key to maintaining stable H+ ion concentrations in biological systems  When there are too many H+ (Acidosis), a buffer will absorb some of them, bringing pH back to normal. The regulation of acid-base balance is concerning the proper balance between chemical acids and bases in the extracellular fluids (which includes the blood plasma). Acid-Base regulation is also called Body Ph The body is very sensitive to its extracellular pH level otherwise outside the acceptable range of pH, proteins are denatured and digested, enzymes lose their ability to function, and death may occur. The body's acid-base balance is normally tightly regulated by buffering agents, the respiratory system, and the renal system, keeping the blood pH between 7.35 and 7.45.  When there are too few H+ (Alkalosis), a buffer will donate some of its own H+ ions to reduce the pH and bring back to normal. 3 Main Systems to Handle H+ Concentration:  1st Line of Defense: Chemical Acid-Base Buffer Systems in ECF  2nd Line of Defense: Lungs: Reach Compensation in 6-12 hrs. Nurses require a good knowledge of the normal body mechanisms which regulate the Acid-Base balance because many ill patients have damaged respiratory, renal and/or metabolic functions.  Hyperventilation= CO2 elimination (Alkalosis)  Hypoventilation= CO2 retention (Acidosis) Kidney: Reach compensation in 3-5 days Acid: Acid is a substance which can donate a H+ or dissociate a H+ First line of defense against pH shift: Base: Base is a substance which can accept a H+  Chemical buffer system pH: The term pH refers to the concentration of hydrogen 1. Bicarbonate buffer system 2. Phosphate buffer system 3. Protein buffer system ions (H*).  In water, the hydrogen ion (H*) is never free but always combined to H₂O to form H₂O ACID BASE REGULATION  The body's metabolic processes constantly produce acids.  These acids must be neutralized and excreted to maintain acid base balance  Normally the body has three mechanisms by which it regulates acid-base balance to maintain the arterial ph 7.35 and 7.45 1. BUFFER SYSTEM 2. THE RESPIRATORY SYSTEM 3. THE RENAL SYSTEM ■ The regulatory mechanisms react at different speeds.  BUFFER reacts immediately  THE RESPIRATORY SYSTEM responds in minutes and reaches maximum effectiveness in hours  THE RENAL RESPONSE takes 2-3 days to responds maximally Buffer: Buffer is a mixture of weak acids and their conjugate bases. The buffer has the ability to oppose changes (stabilize) in pH when acid or base are added to a solution. Second line of defense against pH shift  Physiological buffers 1. Respiratory mechanism (CO2 excretion) 2. Renal mechanism (H+ excretion) HUMAN BLOOD pH IS 7.4 ➤ In normal conditions, blood pH is between 7.35 and 7.45. ➤ To maintain constant the blood pH, two organs play an essential role: 1) LUNGS: breathing in removing carbon dioxide (CO₂) has an effect on the blood pH 2) KIDNEYS: eliminating protons (H+) and retaining bicarbonate (HCO3) has an effect on the blood pH  Kidneys and Lungs contribute to the maintenance of acid-base balance of the body, but for various reasons, this balance can be broken (ACIDOSIS and ALKALOSIS). ALTERATION IN ACID-BASE BALANCE   The acid-base imbalance is produced when the ratio of 1:20 between acid and base content is altered A primary disease or process may alter one side of the ratio  The compensatory process attempts to maintain the other side of the ratio  When compensatory mechanism fails, an acid -base imbalance occurs Types of Acid Base imbalance There are two main types of Acid Base imbalances 1. Respiratory Imbalances: It affects carbonic acid concentration Respiratory acidosis Respiratory alkalosis 2. Metabolic Imbalances: affects the base bicarbonate Metabolic acidosis Metabolic alkalosis Acidosis  An increased acidity in the blood and the other tissues.  The blood pH decreases below 7.35 MAJOR CAUSES:  Diabetes 1 (accumulation of ketoacids)  Prolonged fasting (ketosis)  Respiratory imbalance affects CO₂ concentration. Metabolic imbalance affects HCO3 (Bicarbonate) ion concentration. RESPIRATORY ACIDOSIS Respiratory acidosis: is a clinical disorder in which the PH is less than 7.35 and the PaCo2 is greater than 42mmHg. It may either acute and chronic CAUSES:  Overdose of drugs and substances such as alcohols and aspirin  Elevated plasma level  Elevated carbonic acid  Lactic acidosis (accumulation of lactic acid as occurs as a result of shock or use of certain drugs)  Acute pulmonary edema  Severe kidney disease  Atelectasis  Poisons such as ethylene glycol and methanol  Impaired respiratory muscles  Lung disorders, severe asthma, pneumonia, or pulmonary edema CLINICAL MANIFESTATIONS: Alkalosis ➤ A decreased acidity in the blood and the other tissues. ➤ The blood pH increase above 7.45 MAJOR CAUSES:  Anxiety or panic attacks  Aspirin overdose  Fever or infection  Low levels of oxygen in the blood  Loss of acid due to vomiting or drainage of the stomach  Overactive adrenal gland (due to Cushing syndrome (excess secretion of cortisol) and some adrenal tumors)  Use of diuretics which increase production of urine (for example, thiazides, furosemide, ethacrynic acid) for treatment of high blood pressure, heart failure..  Increased pulse  Increased respiratory rate  Increased blood pressure  Mental cloudiness  Cerebrovascular vasodilation  increased intra cranial pressure  papilledema  Feeling of fullness in head MEDICAL MANAGEMENT:  Anxiety: patient is instructed to breath more slowly to allow co2 to accumulate  Sedative may be required to relieve hyperventilation in very anxious patients ■ Treatment is directed by improving ventilation ■Pharmacologic agent  bronchodilators  anti biotic Respiratory Imbalances  anti coagulants Respiratory Acidosis: It results from alveolar hypoventilation and hypercapnia. (Retention of CO2 in lung). ■Pulmonary hygiene measures  adequate hydration  mechanical ventilation RESPIRATORY ALKALOSIS Respiratory alkalosis: is a clinical condition in which the arterial ph is greater than 7.45 and the paco2 is less than 38mmhg  pH<7.35 and PaCO, > 45mm Hg.  Acidosis: Increased CO₂ Respiratory Alkalosis: It results from alveolar hyperventilation and hypocapnia. (Excessive elimination of CO2)  pH > 7.45 and PaCO2 <35 mm Hg.  Alkalosis: decreasedCO₂ CAUSES:  Respiratory alkalosis is always due to hyperventilation  Anxiety  Hypoxemia  Decreased serum bicarbonate levels Metabolic acidosis: is a clinical disturbance characterized by a low pH (increased hydrogen ions) and a low plasma bicarbonate concentration  Chronic hepatic insufficiency and cerebral tumors  It can be produced by a gain of hydrogen ions or a loss of bicarbonate  It can be divided clinically into two forms according to the values of the serum anion  Chronic hypocapnia CLINICAL MANIFESTATION:  Light headedness due to vasoconstriction  Decreased cerebral flow  Numbness tinnitus,  Loss of consciousness  Tachycardia  Ventricular and arterial dysrhythmias MEDICAL MANAGEMENT:  METABOLIC ACIDOSIS Treatment depends on the underlying cause respiratory alkalosis CLINICAL MANIFESTATION:          Headache Confusion Drowsiness Increased respiratory rate depth Nausea and vomiting Decreased blood pressure Cold and clammy skin Dysrhythmias shock DIAGNOSTIC FINDINGS: MEDICAL MANAGEMENT:  Arterial blood gas analysis  Sufficient chloride must be supplied for  Change includes a low bicarbonate level (less than 22 meq/l)  kidney to absorb sodium with chloride  Administering sodium chloride fluids  Histamine-2 receptor antagonists, such as cimetidin (tagamet). Reduces the gastric hcl, thereby decreasing the metabolic alkalosis associated with gastric suction  Input and output should be monitored  Low ph (less than 7.35)  Calculation of anion gap is helpful  ECG will detect dysrhythmias caused by increased potassium MEDICAL MANAGEMENT  Treatment is directed at correcting the metabolic defect  If problem results from excessive intake of chloride, treatment is aimed at eliminating the source of chloride  Bicarbonate is administered if the ph is less than 7.1  Serum potassium level is monitored closely and hypokalemia is corrected as acidosis reversed METABOLIC ALKALOSIS Metabolic alkalosis: is a clinical disturbance characterized by a high ph (decreased H+ ions concentration) and a high plasma bicarbonate concentration. It can be produced by a gain of bicarbonate or a loss of H+ ions CAUSES:  Vomiting  gastric suction  Pyloric stenosis  Diuretic therapy that promotes excretion of potassium  Cystic fibrosis  Chronic ingestion of milk and calcium carbonate CLINICAL MANIFESTATION  Tingling of the fingers and toes  Dizziness   Symptoms of hypocalcemia is often the symptoms of alkalosis Ventricular disturbances (ph increase above 7.6) Metabolic Imbalances: Metabolic Acidosis: a systemic disoreser: it results from non caebonic(non volatile) acids increase in plasmawith loss of HCO3 from the EFC causing a decrease in pH( increase H+)  Acidosis: decreased HCO 3 Metabolic Alkalosis: a systemic disorder: it results from an increase in plasma HCO3 and excessive loss of metabolic acids from ECF causing a increase in pH ( decrease H+)  Acidosis: increased HCO 3 Component of the Arterial Blood Gas (ABGS) ABG provide following details about: pH: Measurement of acidity or alkalinity, based on the e hydrogen (H+) ions present. The normal range is 7.35 to 7.45. PaO2: The partial pressure of oxygen exerted on the arterial. The normal range is 80 to 100 mm Hg. Pressure of oxygen flowing from lung to blood. Sa02: The arterial blood oxygen saturation or is the percentage of hemoglobin binding sites that are occupied with O₂. The normal range is 95% to 100%. NANDA Nursing Diagnoses   Respiratory acidosis/alkalosis  Impaired gas exchange PaCO2:The amount of carbon dioxide dissolved in arterial blood. The normal range is 35 to 45 mm Hg. HСО2: The calculated value of the amount of bicarbonate in the blood stream. The normal range is 22 to 26 mEq/liter  Ineffective breathing pattern  Metabolic acidosis/alkalosis  Decreased cardiac output Nursing Interventions  For all acid-base imbalances, it is imperative to treat the underlying cause. Steps to an ABG Interpretation Acid-base evaluation/interpretation requires a focus on three reported components:  pH  PaCO2  HCO3 ► Respiratory acidosis: To determine the type of imbalance, follow these steps:  Oxygen therapy,  maintain patent airway, and Step 1: Look at pH. If 7.35, diagnose as acidosis. If > 7.45, diagnose as alkalosis. Enhance gas exchange (positioning and breathing techniques, ventilatory support, bronchodilators, mucolytics). Step 2: Look at PaCO2 and HCO3- simultaneously.   ► Respiratory alkalosis:    Oxygen therapy. anxiety reduction interventions, Rebreathing techniques. ► Metabolic acidosis: Varies with causes.  If DKA, administer insulin;  If related to Gl losses, administer antidiarrhe and provide rehydration;  if serum bicarbonate is low, administer sodiu bicarbonate (1 mEq/kg). ►Metabolic alkalosis: Varies with causes.     If Gl losses, administer antiemetics, fluids, and electrolyte replacements; if related to potassium depletion, discontinue causative agent or potassium-sparing diuretic. Complications and Nursing Implications a. Convulsions, Coma, and Respiratory Arrest b. Seizure precautions and management c. Life-support interventions  Determine which one is in the normal range. Then, conclude that the other is the indicator of imbalance. Diagnose < 35 or 45 PaCO2 as respiratory in origin. Diagnose 22 or 26 HCO3 as metabolic in origin. Step 3 Combine diagnoses of Steps 1 and 2 to name the type of imbalance Step 4:Evaluate the PaO2 and the SaO2.  If the results are below the normal range, the client is hypoxic. Step 5: Determine compensation as follows: Uncompensated: The pH will be abnormal and either the HCO3 - or the PaCO2 will be abnormal. Partially compensated: The pH, HCO3-, and PaCO2 will be abnormal. Fully compensated: The pH will be normal, but the PaCO2 and HCO3-will both be abnormal.  Then, looking back at the pH will provide a clue as to which system initiated the problem, respiratory or metabolic. If the pH is < 7.40, think "acidosis" and determine which system has the acidosis value. If the pH is > 7.40, think "alkalosis" and determine which system has the alkalosis value