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Acid-Base, Fluids and Electrolytes
The document discusses fluid, electrolyte, and acid-base balance in the human body. It covers topics like intracellular and extracellular fluid composition and balance, electrolytes like sodium, potassium, and their regulation. It also discusses acid-base balance, the bicarbonate buffer system, and four major acid-base imbalances - respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis. Key organs involved in regulation are the lungs and kidneys.
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Acid-Base, Fluids and Electrolytes
- 2. Fluid and Electrolytes At the end of this lecture, we will be able to: Discuss the importance of homeostasis. Enumerate and discuss the importance of laboratory assessment of fluid and electrolyte balance. Interpret laboratory results of fluids and electrolytes. correlate clinically
- 3. Acid-Base Balance Discussthe control of pH in the blood with emphasis on the role of lungs/kidneys Enumerate and discuss the four major possible abnormalities of acid-base balance Metabolic vs Respiratory Acidosis vs Alkalosis Compensated vs Uncompensated Correlate clinically
- 4. A delicate balanceof fluids, electrolytes, acids and bases is required to maintain good health. This balance is called Homeostasis.
- 5. Intracellular fluid (ICF) foundwithin the cells of the body constitutes 2/3 of total body fluid in adults major cation is potassium Extracellular fluid (ECF) found outside the cells accounts of 1/3 of total body fluid major cation is sodium
- 6. Osmosis Solutes movement of wateracross cell membranes from less concentrated to more concentrated substances dissolved in a liquid Osmolality the concentration within a fluid
- 7. Diffusion Filtration movement of moleculesin liquids from an area of higher concentration to lower concentration fluid and solutes move together across a membrane from area of higher pressure to one of lower pressure Active Transport substance moves across cell membranes from less concentrated solution to more concentrated requires a carrier and energy.
- 8.
- 9. Sodium Potassium Chloride Phosphate Magnesium Calcium Bicarbonate Electrolytes are importantfor: Maintaining fluid balance Contributing to acid-base regulation Facilitating enzyme reactions Transmitting neuromuscular reactions
- 10. Sodium (Na) NV135-145 mEq/L Potassium (K) NV 3.5 – 5.5 mEq/L Ion-selective electrodes most common method Atomic absorption spectroscopy reference method Osmolality NV 275-300mOsm/kg H2O Freezing point depression, most common method (serum or urine)
- 11. Hypernatremia Conditions causing dehydration andabsolute Na excess Hyponatremia Conditions causing loss of Na and increase in body water (dilutional)
- 12. Hyperkalemia Conditions causingabsolute increase in body K and extracellular shift of K Hypokalemia Conditions causing loss of K, decreased K intake, and intracellular shift of K
- 13. Hyperosmolality (osmolal gap) Normal: dehydration, high Na, azotemia, DI Moderately elevated: Ketoacidosis, Renal and lactic acidosis Markedly elevated: alcohol ingestion and poisoning of selected substances
- 14. Water Distribution 60%of BW 60% ICF and 33% ECF 8% in plasma freely permeable Na, K, glucose, urea and protein balance between intake and body loss
- 15. Sodium Distribution major ECcation 135 to 145 mmol/L relatively impermeable leakage is actively pump out by Na-K ATPase balance intake and loss excessive intake contributes to hypertension massive internal turnover
- 16. Potassium Distribution major ICcation constant tendency to diffuse down its concentration gradient opposed by Na-K ATPase EC concentration is accessible for measurement
- 17. Changes in H2Ocontent independent of the amount of solute will alter osmolality Water Loss movement from ICF to ECF stimulation of ADH secretion stimulates thirst center ECF volume is directly dependent upon the total sodium content Sodium Balance: regulated by its renal excretion (GFR, aldosterone); atrial natriuretic hormone and natriuretic factor (cardiac glycosides) which acts against Na-K ATPase
- 18. Abnormalities: Combined Waterand Sodium Depletion Pure Water Depletion Pure Sodium Depletion (Hyponatremia) Combined Water and Sodium Excess Pure Water Excess Pure Sodium Excess (Hypernatremia)
- 19. Hypotonic fluidloss thirst, dryness of mouth, difficulty of swallowing, weakness, confusion weight loss, dry mucous membrane, decreased saliva secretion, loss of skin turgor, decreased urine volume Causes: Increased Loss: renal, GIT, lungs, skin Decreased Intake
- 20. Isotonic or hypotonicfluid loss hypertonic loss (excessive sweating) corresponding decrease in ECF response: aldosterone, inc. reabsorption, low GFR increased Hct and plasma protein reduced ECF volume peripheral circulatory failure plasma Na concentration isotonic loss = decreased hypotonic loss = increased Causes: Excessive Loss or Inadequate Intake
- 21. Failure of normal excretion Excessiveintake (iatrogenic)
- 22. Impairment of waterexcretion hyponatremia load is shared by ICF and ECF cerebral over-hydration causes: increased intake and decreased excretion
- 23. Peripheral edema, dyspnea, pulmonaryedema, venous congestion, HPN, effusions, weight gain Causes: Increased Intake, Decreased Excretion mostly has paradoxical hyponatremia due to defect in free water excretion
- 24. Plasma Na isdependent upon relative amounts of Na and water in the plasma Indications for serum Na determination: dehydration or excessive fluid loss - as a guide to appropriate replacement on parenteral fluid replacement who are unable to indicate or respond to thirst with unexplained confusion, abnormal behavior or signs of CNS irritability Correlated with clinical observations
- 25. Balance is controlledby kidneys and GIT related to Hydrogen Ions Kidney: complete reabsorption and active secretion amount of Na for reabsorption relative availability of K and H ability to secrete H aldosterone concentration rate of flow of tubular fluid
- 26. GIT: secreted ingastric juice, reabsorb in the SI, secreted in LI in exchange of Na movement between ECF and ICF influence of insulin integrity of cell membranes Na-K ATPase H ion concentration
- 27. Output exceeds intake inadequateintake is rarely the sole cause increased loss drug therapy redistribution in the ECF and ICF asymptomatic, neuromuscular disturbance, cardiac, renal (impaired concentration), metabolic alkalosis
- 28. Excessive intake ifexcretion is decreased iatrogenic and parenteral decreased excretion redistribution of ECF and ICF spurious (hemolysis, delayed separation, contamination)
- 29. Hypokalemia low STwave T depression/inversion prolonged PR interval prominent U wave Hyperkalemia peaking of T waves loss of P waves abnormal QRS complexes ventricular fibrillation
- 30. Acid-Base balance is: theregulation of HYDROGEN ions.
- 31. The acidity oralkalinity of a solution is measured as pH. The more acidic a solution, the lower the pH. The more alkaline a solution , the higher the pH. Water has a pH of 7 and is neutral. The pH of arterial blood is normally between 7.35 and 7.45
- 32. The more Hydrogenions, the more acidic the solution and the LOWER the pH The lower Hydrogen concentration, the more alkaline the solution and the HIGHER the pH
- 33. Know what isnormal.
- 34. Regulate pH bybinding or releasing Hydrogen Most important buffer system: Bicarbonate-Carbonic Acid Buffer System (Blood Buffer systems act instantaneously and thus constitute the body’s first line of defense against acidbase imbalance)
- 36. Lungs help regulateacid-base balance by eliminating or retaining carbon dioxide pH may be regulated by altering the rate and depth of respirations changes in pH are rapid, occurring within minutes normal CO2 level 35 to 45 mm Hg
- 37. Kidneys the long-termregulator of acid-base balance slower to respond may take hours or days to correct pH kidneys maintain balance by excreting or conserving bicarbonate and hydrogen ions normal bicarbonate level 22 to 26 mEq/L.
- 38. Age especially infantsand the elderly Gender and Body Size amount of fat Environmental Temperature Lifestyle stress
- 39. Respiratory Acidosis Respiratory Alkalosis MetabolicAcidosis Metabolic Alkalosis
- 40. Mechanism Hypoventilation orExcess CO2 Production Etiology COPD Neuromuscular Disease Respiratory Center Depression Late ARDS Inadequate mechanical ventilation Sepsis or Burns Excess carbohydrate intake
- 41. Symptoms Dyspnea, Disorientationor coma Dysrhythmias pH < 7.35, PaCO2 > 45mm Hg Hyperkalemia or Hypoxemia Treatment Treat underlying cause Support ventilation Correct electrolyte imbalance IV Sodium Bicarb
- 42. Risk Factors andetiology Hyperventilation due to extreme anxiety, stress, or pain elevated body temperature overventilation with ventilator hypoxia salicylate overdose hypoxemia (emphysema or pneumonia) CNS trauma or tumor
- 43. Symptoms Tachypnea orHyperpnea Complaints of SOB, chest pain Light-headedness, syncope, coma, seizures Numbness and tingling of extremities Difficult concentrating, tremors, blurred vision Weakness, paresthesias, tetany Lab findings pH above 7.45 CO2 less than 35
- 44. Treatment Monitor VSand ABGs Treat underlying disease Assist client to breathe more slowly Help client breathe in a paper bag or apply rebreather mask Sedation
- 45. Risk Factors/Etiology Conditionsthat increase acids in the blood Renal Failure DKA Starvation Lactic acidosis Prolonged Toxins diarrhea (antifreeze or aspirin) Carbonic anhydrase inhibitors - Diamox
- 46. Symptoms Kussmaul’s respiration Lethargy, confusion, headache, weakness Nausea and Vomiting Lab: pH below 7.35 Bicarb less than 22 Treatment treat underlying cause monitor ABG, I&O, VS, LOC, NaHCO3
- 47. Risk Factors/Etiology Acidloss due to vomiting gastric suction Loss of potassium due to steroids diuresis Antacids (overuse of)
- 48. Symptoms Hypoventilation (compensatory) Dysrhythmias, dizziness Paresthesia, numbness, tingling of extremities Hypertonic muscles, tetany Lab: pH above 7.45, Bicarb above 26 CO2 normal or increased w/comp Hypokalmia, Hypocalcemia Treatment I&O, VS, LOC give potassium treat underlying cause
- 50. 1. Look atthe pH is the primary problem acidosis (low) or alkalosis (high) 2. Check the CO2 (respiratory indicator) is it less than 35 (alkalosis) or more than 45 (acidosis) 3. Check the HCO3 (metabolic indicator) is it less than 22 (acidosis) or more than 26 (alkalosis) 4. Which is primary disorder (Respiratory or Metabolic)? If the pH is low (acidosis), then look to see if CO2 or HCO3 is acidosis (which ever is acidosis will be primary). If the pH is high (alkalosis), then look to see if CO2 or HCO3 is alkalosis (which ever is alkalosis is the primary). The one that matches the pH (acidosis or alkalosis), is the primary disorder.
- 51. The Respiratory systemand Renal systems compensate for each other attempt ABG’s show that compensation is present when the to return the pH to normal pH returns to normal or near normal If the nonprimary system is in the normal range (CO2 35 to 45) (HCO3 22-26), then that system is not compensating for the primary. For example: In respiratory acidosis (pH<7.35, CO2>45), if the HCO3 is >26, then the kidneys are compensating by retaining bicarbonate. If HCO3 is normal, then not compensating.
- 52.