Presentation on theme: "Fluid, electrolyte, and acid-base imbalances"— Presentation transcript:
1 Fluid, electrolyte, and acid-base imbalances Zoya Minasyan, RN, MSN-Edu
2 PurposeMaintain a balance between acids and bases to achieve homeostasis: State of equilibriumHealth problems lead to imbalanceDiabetes mellitusVomiting and diarrheaRespiratory conditionsChemotherapy- N/V
3 pH Measure of H+ ion concentration Blood is slightly alkaline at pH 7.35 to 7.45.<7.35 is acidosis.>7.45 is alkalosis.
4 Range of pHFig The normal range of plasma pH is 7.35 to A normal pH is maintained by a ratio of 1 partcarbonic acid to 20 parts bicarbonate.
5 Regulators of Acid/Base Metabolic processes produce acids that must be neutralized and excreted.Regulatory mechanismsBuffersRespiratory systemRenal systemThe regulatory mechanisms react at different speeds. Buffers react immediately; the respiratory system responds in minutes and reaches maximum effectiveness in hours; the renal response takes 2 to 3 days to respond maximally, but the kidneys can maintain balance indefinitely in chronic imbalances.
6 Regulators of Acid/Base Buffers: Act chemically to neutralize acids or change strong acids to weak acidsPrimary regulatorsReact immediatelyCannot maintain pH without adequate respiratory and renal functionThe buffers in the body includecarbonic acid–bicarbonatemonohydrogen- dihydrogen phosphateintracellular and plasma proteinhemoglobin
7 Regulators of Acid/Base Respiratory system: Eliminates CO2Respiratory center in medullacontrols breathing.Responds within minutes/hours to changes in acid/base.Increased respirations lead toincreased CO2 eliminationdecreased CO2 in blood.
8 Regulators of Acid/Base When released into circulation, CO2 enters RBCs and combines with H2O to form H2CO3.This carbonic acid dissociates into hydrogen ions and bicarbonate.The free hydrogen is buffered by hemoglobin molecules, and the bicarbonate diffuses into the plasma.In the pulmonary capillaries, this process is reversed, and CO2 is formed and excreted by the lungs.As a compensatory mechanism, the respiratory system acts on the CO2 + H2O side of the reaction by altering the rate and depth of breathing to “blow off” (through hyperventilation) or “retain” (through hypoventilation) CO2.If a respiratory problem is the cause of an acid-base imbalance (e.g., respiratory failure), the respiratory system loses its ability to correct a pH alteration.
9 Regulators of Acid/Base Renal system: Eliminates H+ and reabsorbs HCO3-Reabsorption and secretion of electrolytes (e.g., Na+, Cl-)Responds within hours to days
10 Regulators of Acid/Base The three mechanisms of acid elimination aresecretion of small amounts of free hydrogen into the renal tubule,combination of H+ with ammonia (NH3) to form ammonium (NH4+), andexcretion of weak acids.The body depends on the kidneys to excrete a portion of the acid produced by cellular metabolism.Thus the kidneys normally excrete acidic urine (average pH equals 6).As a compensatory mechanism, the pH of the urine can decrease to 4 and increase to 8.pH of urine is close to neutral (7) but can normally vary between 4.4 and 8.
11 Alterations in Acid-Base Balance Imbalances occur when compensatory mechanisms fail.Classification of imbalancesRespiratory: Affect carbonic acid concentrationMetabolic: Affect bicarbonateAn 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 (e.g., CO2 retention in pulmonary disease). The compensatory process attempts to maintain the other side of the ratio (e.g., increased renal bicarbonate reabsorption).Acidosis can be caused by an increase in carbonic acid (respiratory acidosis) or a decrease in bicarbonate (metabolic acidosis).
12 Respiratory Acidosis Carbonic acid excess caused by Compensation HypoventilationRespiratory failureCompensationKidneys conserve HCO3- and secrete H+ into urine.
13 Respiratory Acidosis Hypoventilation results in a buildup of CO2 carbonic acid accumulates in the bloodCarbonic acid dissociates, liberating H+, and a decrease in pH occurs.If CO2 is not eliminated from the blood, acidosis results from the accumulation of carbonic acid.In acute respiratory acidosis, the renal compensatory mechanisms begin to operate within 24 hours.
14 Respiratory Alkalosis Carbonic acid deficit caused byHyperventilationHypoxemia from acute pulmonary disordersAnxiety, CNS disorders, and mechanical over-ventilation also increase ventilation rate and decrease the partial pressure of arterial carbon dioxide (PaCO2) level.In acute respiratory alkalosis, aggressive treatment of the causes of hypoxemia is essential and usually does not allow time for compensation to occur. However, buffering of acute respiratory alkalosis may occur with shifting of bicarbonate (HCO3–) into cells in exchange for Cl–.
15 Metabolic Acidosis Base bicarbonate deficit caused by KetoacidosisLactic acid accumulation (shock)Severe diarrheaKidney diseaseMetabolic acidosis (base bicarbonate deficit) occurs when an acid other than carbonic acid accumulates in the body, or when bicarbonate is lost from body fluids.Compensatory mechanismsIncreased CO2 excretion by lungsKussmaul respirations (deep and rapid)Kidneys excrete acid
16 Metabolic Alkalosis Base bicarbonate excess caused by Gain of HCO3- Prolonged vomiting or gastric suctionGain of HCO3-Compensatory mechanismsDecreased respiratory rate to increase plasma CO2Renal excretion of HCO3-
17 Blood Gas ValuesArterial blood gas (ABG) values provide information aboutAcid-base statusUnderlying cause of imbalanceBody’s ability to regulate pHOverall oxygen status
18 Interpretation of ABGs Diagnosis in six steps:Evaluate pH.Analyze PaCO2.Analyze HCO3-.Determine if CO2 or HCO3- matches the alteration.Decide if the body is attempting to compensate.
19 Normal Blood Gas Values Table Normal Arterial Blood Gas Values *.
20 Sample ABG Interpretation Table Arterial Blood Gas (ABG) Analysis.
22 Interpretation of ABGs pH 7.18PaCO2 38 mm HgPaO2 70 mm HgHCO3- 15 mEq/LWhat is this?Metabolic acidosis
23 Interpretation of ABGs pH 7.58PaCO2 35 mm HgPaO2 75 mm HgHCO3- 50 mEq/LWhat is this?Metabolic alkalosis
24 QuestionA patient with an acid-base imbalance has an altered potassium level. The nurse recognizes that the potassium level is altered because: 1. Potassium is returned to extracellular fluid when metabolic acidosis is corrected. 2. Hyperkalemia causes an alkalosis that results in potassium being shifted into the cells. 3. Acidosis causes hydrogen ions in the blood to be exchanged for potassium from the cells. 4. In alkalosis, potassium is shifted into extracellular fluid to bind excessive bicarbonate.324
25 AnswerAnswer: 3Rationale: Changes in pH (hydrogen ion concentration) will affect potassium balance.In acidosis,hydrogen ions accumulate in the intracellular fluid (ICF),and potassium shifts out of the cell to the extracellular fluid to maintain a balance of cations across the cell membrane.In alkalosis,ICF levels of hydrogen diminish,and potassium shifts into the cell.If a deficit of H+ occurs in the extracellular fluid, potassium will shift into the cell.Acidosis is associated with hyperkalemiaAlkalosis is associated with hypokalemia.
26 Case Study 1: Jeri Jeri’s been on a 3-day party binge. Friends are unable to awaken her.Assessment reveals level of consciousness difficult to arouse.Respiratory rate 8Shallow breathing patternDiminished breath soundsWhat ABGs do you expect?What is your treatment?What ABGs do you expect?Respiratory acidosis reflected by pH <7.35 and PCO2 >45 mm Hg. The HCO3 will be normal (20-30 mEq/L) if her respiratory depression has lasted less than 24 hours; if longer than 24 hours, the HCO3 may be elevated as the result of compensation. The PaO2 may be <80 mm Hg because of respiratory depression leading to hypoxemia.2. What is your treatment?Determine the cause of the respiratory depression. If induced by opioids or benzodiazepines, treat with appropriate antagonists. If induced by alcohol or other CNS depressants, breathing must be stimulated until the effects of drugs have worn off. Mechanical ventilation may be necessary to increase respiratory rate and depth, increasing oxygenation and promoting excretion of carbon dioxide.26
27 Case Study 1: Jeri What ABGs do you expect? Respiratory acidosis reflected by pH <7.35 and PCO2 >45 mm Hg. The HCO3 will be normal (20-30 mEq/L) if her respiratory depression has lasted less than 24 hours; if longer than 24 hours, the HCO3 may be elevated as the result of compensation. The PaO2 may be <80 mm Hg because of respiratory depression leading to hypoxemia.2. What is your treatment?Determine the cause of the respiratory depression. If induced by opioids or benzodiazepines, treat with appropriate antagonists. If induced by alcohol or other CNS depressants, breathing must be stimulated until the effects of drugs have worn off. Mechanical ventilation may be necessary to increase respiratory rate and depth, increasing oxygenation and promoting excretion of carbon dioxide.
29 Case Study 2: Mayna 1. What ABGs do you expect? Respiratory alkalosis indicated by pH >7.45 and PCO2 <35 mm Hg. The HCO3 will be normal (20-30 mEq/L) because compensation will not occur in this acute event.2. What is your treatment?Relieve her anxiety and coax her to take slow breaths. Carbon dioxide may be administered by mask, or she may be asked to breathe into a paper bag placed over her nose and mouth.
30 Case Study 3: Allen 17 years old History of Frequent urination Feeling badFatigueConstant thirstFrequent urinationBlood sugar is 484 mg/dL.Respirations are 28 and deep.Breath has a fruity odor.Lungs are clear.What ABGs do you expect?What is your treatment?1. What ABGs do you expect?A diabetic ketoacidosis is a metabolic acidosis indicated by a pH <7.35 and a HCO3 <20 mEq/L. The PCO2 will be within the normal range if the acidosis is uncompensated, but will be <35 mm Hg if compensation has occurred. The PaO2 will not be affected.2. What is your treatment?Administration of insulin to promote normal glucose metabolism and administration of fluids and electrolytes to replace those lost because of the hyperglycemia.
31 Case Study 3: Allen What ABGs do you expect? A diabetic ketoacidosis is a metabolic acidosis indicated by a pH <7.35 and a HCO3 <20 mEq/L. The PCO2 will be within the normal range if the acidosis is uncompensated, but will be <35 mm Hg if compensation has occurred. The PaO2 will not be affected.2. What is your treatment?Administration of insulin to promote normal glucose metabolism and administration of fluids and electrolytes to replace those lost because of the hyperglycemia.
32 Fluid volume deficit Can occur with Abnormal loss of body fluids- Diarrhea, hemorrhage, polyuriaInadequate fluid intakeShift of fluid from plasma into interstitial spaceTreatmentCorrect the underlining causeReplace the fluid and electrolyte (LR or NS isotonic solutions)
33 Fluid volume excess May result from excessive intake of fluid Abnormal retention of fluids(heart failure, renal failure)Shift of fluid from interstitial fluid into plasma fluidCollaborative careID primary causeDiuretics and fluid restrictionRestriction of Na intakeFluid excess may result to ascites or pleural effusion, and paracentesisi or thoracentsis may be necessary.
34 Commonly prescribed crystalloid solutions Dextrose in water5% isotonic10% hypertonicSaline0.45% hypotonic0.9% isotonic3.0% hypertonicDextrose in Saline5% in 0.225% isotonic5% in 0.45% hypertonic5% in 0.9% hypertonicMultiple Electrolyte SolutionsRinger’s solution- isotonic, includes CL, Na, K, CaLactated Ringer’s solution- isotonic-Na, K, Cl, Ca, and lactate(the precursor of bicarbonate)
35 CVADsCatheters placed in large blood vessels of people who require frequent access to the vascular systemSubclavian vein, jugular veinThree different methodsCentrally inserted catheter(by MD)Peripherally inserted central catheterImplanted ports( by MD)In contrast to CVADs, the basic IV catheter is inserted into a peripheral vein in the hand, inside of the arm, or antecubital fossa and is used for short-term IV access.Centrally inserted catheters and implanted ports must be placed by a physician, but PICCs can be inserted by a nurse with specialized training.35
36 CVADsPermit frequent, continuous, rapid, or intermittent administration or monitoringIndicated for patients with limited peripheral vascular access or need for long-term vascular accessExamples of need include chemotherapy, long-term administration of antibiotics/pain medication, infusion of PN, and access for multiple blood draws/hemodialysis.Advantages of CVADs include a reduced need for multiple venipunctures, decreased risk of extravasation injury, and immediate access to the central venous system.The major disadvantages of CVADs are an increased risk of systemic infection and the invasiveness of the procedure.36
37 Centrally Inserted Catheter Inserted into a vein in the neck, chest, or groin with tip resting in the distal end of the superior vena cavaSingle, double, triple, or quad lumenNontunneled or tunneledInserted into subclavian, jugular, or femoral vein37
41 Implanted Infusion Ports Central venous catheter connected to an implanted, single or double subcutaneous injection portPort is metal sheath with self-sealing silicone septum.The catheter is placed into the desired vein, and the other end is connected to a port that is surgically implanted in a subcutaneous pocket on the chest wall.41
42 Implanted Infusion Port Huber- point needle, 90 degree angle
43 Implanted Infusion Port Port accessed with special Huber-point needleAdvantagesGood for long-term therapyLow risk of infectionCosmetic discretionCare requires regular flushing.Complication: (table page 330)Cath occlusion(kinked, precipitate build up)Embolism( dislodgment of thrombus, air entry, cath breaking)Cath related infectionCath MigrationImplanted ports have been developed that are safe for injection of radiopaque contrast media at high pressures and controlled rates. For patients who already have poor peripheral venous access, the ability to use the port to inject contrast media decreases discomfort from venipuncture and helps lower the risk for extravasation of vesicant contrast media. Care requirements include regular flushing. Formation of “sludge” (accumulation of clotted blood and drug precipitate) may also occur within the port septum.43
44 Nursing Management Inspect catheter and insertion site. Assess pain. Change dressing and clean according to institution policies.Change injection caps.Flushing is important.Catheter and insertion site assessments include inspection of the site for redness, edema, warmth, drainage, and tenderness or pain. Observation of the catheter for misplacement or slippage is important.Transparent dressing or gauze may be used.Discuss cleaning techniques with chlorhexidine-based preparations, povidone-iodine, and isopropyl alcoholTeach the patient to turn the head to the opposite side of the CVAD insertion site during cap change. Flushing: Use a normal saline solution in a syringe that has a barrel capacity of 10 mL or more to avoid excess pressure on the catheter. If resistance is felt, force should not be applied.44
45 Removing CVADs Should be done according to policy and procedures. Gently withdraw.Apply pressure.Ensure that catheter tip is intact.In many agencies, nurses with demonstrated competency can remove PICCs and nontunneled central venous catheters.45