docx-5.pdf - N5315 Advanced Pathophysiology Fluid and Electrolytes Module 2 part 1 Core Concept and Objectives with Advanced Organizers Fluid and

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Unformatted text preview: N5315 Advanced Pathophysiology Fluid and Electrolytes Module 2 part 1 Core Concept and Objectives with Advanced Organizers Fluid and Electrolytes • 1. Analyze the pathologic consequences of fluid volume disorders on the mechanisms of fluid homeostasis. a. Explain the three main fluid compartments and describe how fluid shifts between the compartments and the implications for clinical practice. Pattern of Fluid Fluid Compartments Definition Clinical Implications Shifts Both in and out of the interstitial and intracellular spaces Volume overload The intravascular Venous retention space contains 20% Hypertonic IV Intravascular Increased venous of the total body solution, when pressure water. administered, will edema increase the solute concentration in the intravascular space. Fluid will shift from intracellular into the extracellular space Due to the increase in (intravascular). solute concentration in the intravascular Edema: space, water will flow Accumulation of via osmosis from the fluid in interstitial The interstitial space extracellular space to space Interstitial contains 20% of the the intravascular -influenced by total body water. space. This will leave increased hydrostatic the extravascular pressure, low plasma space with a higher oncotic pressure, concentration of increased cap solutes than the membrane intracellular space. permeability, lymphatic channel obstruction Fluid flows via osmosis from the intracellular space into the extracellular space to equalize the concentration of solutes. This will The intracellular cause the cell to space contains the shrink. Water will The cell will Intracellular largest portion of the concentration of solutes than the intracellular space. Intracellular The intracellular space contains the largest portion of the total body water (40%). Fluid flows via osmosis from the intracellular space into the extracellular space to equalize the concentration of solutes. This will cause the cell to shrink. Water will continue to flow into the intravascular space from the extracellular space if the intravascular space still remains more concentrated than the extracellular space. increased cap membrane permeability, lymphatic channel obstruction The cell will continue to shrink. b. Analyze the principles of fluid balance and describe the implications for clinical practice. Mechanisms of Fluid Balance Definition Clinical Implications Osmolality is the measure of solute concentration in a solution. In humans, it is basically the concentration of Is preferred measure of the plasma. It is the osmotic activity in clinical concentration of those solutes assessments. that do not readily cross the cell membranes and in effect Osmolality Plasma osmolality is 280-295 contribute to the osmolality. mOsm/Kg; the low side may even go as low as 275 mOsm/ Controls distribution and Kg. movement of water between body compartments. Measure concentration of wgt per water in mOsm/kg. Passive- the movement of water from an area of high concentration of solute to one of lower concentration Osmosis (Book p. 30: movement of water from area of a high concentration to a low concentration) For osmosis to occur, membrane must be more permeable to water than to solutes and the concentration of solutes must be greater so Affected by the oncotic pressure of both the capillaries & interstitial space Albumin exerts great osmotic force Controls distribution and movement of water between body compartments. Measure concentration of wgt per water in mOsm/kg. Passive- the movement of water from an area of high concentration of solute to one of lower concentration Osmosis Osmotic Pressure (Book p. 30: movement of water from area of a high concentration to a low concentration) For osmosis to occur, membrane must be more permeable to water than to solutes and the concentration of solutes must be greater so water moves easy. Pulling- the amount of pressure or force that is exerted by solute molecules of a given compartment Amt of hydrostatic pressure required to oppose the osmotic movement of water. even go as low as 275 mOsm/ Kg. Affected by the oncotic pressure of both the capillaries & interstitial space Albumin exerts great osmotic force Factors that determine osmotic pressure are thickness of plasma membrane, size of molecules, concentration of molecules, or the concentration gradient, and solubility of molecules in the membrane. Ex: movement of water in relation to hydrostatic and osmotic force occur in the glomerulus of the kidney and capillaries of microcirculation. Mechanical force of water pushing against cellular membrane. Hydrostatic Pressure (HP) Oncotic Pressure Effective Arterial Blood Blood pressure- pushes fluid outside of the vessels, the force of fluid against the walls of a compartmentvenous obstruction, Na and water retention Colloid pressure keeps water inside the compartment, attracts water from interstitial space back into the capillarylosses or diminished albumin Overall osmotic effect of colloids such as plasma proteins The amount of blood within the arterial space- ECF HP is the BP generated in vessels by contraction of the heart. Albumin: main plasma protein Low albumin→ water leaves compartment causing edema Decreased ECF volume= decreased EABC Hydrostatic Pressure (HP) Oncotic Pressure Effective Arterial Blood Volume Antidiuretic Hormone outside of the vessels, the force of fluid against the walls of a compartmentvenous obstruction, Na and water retention Colloid pressure keeps water inside the compartment, attracts water from interstitial space back into the capillarylosses or diminished albumin Overall osmotic effect of colloids such as plasma proteins The amount of blood within the arterial space- ECF changes will cause changes in the EABV in the same direction Secreted by pituitary gland in response to water deficit, Na excess, or hypotension. Causes kidneys to reabsorb water, increasing plasma volume vessels by contraction of the heart. Albumin: main plasma protein Low albumin→ water leaves compartment causing edema Decreased ECF volume= decreased EABC Increased ECF volume = increased EABC High levels indicate: Syndromes of Inappropriate ADH production (SIADH) Cancers (leukemia, lymphoma, lung cancer, pancreatic, bladder, and brain cancer) Guillain-Barre syndrome Multiple sclerosis Epilepsy Acute intermittent porphyria Cystic fibrosis Emphysema Tuberculosis HIV/AIDS Nephrogenic diabetes insipidus Dehydration Trauma Surgery greatly increased ADH may be seen with systemic cancers that produce ADH Low levels indicate: Central diabetes insipidus Compulsive water drinking Low serum osmolality Renin Angiotensin Aldosterone System Activated by low blood volume, triggers release of renin which converts angiotensinogen to angiotensin I. ACE converts angiotensin I to angiotensin II which causes arterial vasoconstriction and If blood flow to the kidneys diminishes (hemorrhaging) or sodium level drops renin is secreted. Renin causes vasoconstriction and increase Low levels indicate: Central diabetes insipidus Compulsive water drinking Low serum osmolality Renin Angiotensin Aldosterone System Natriuretic Hormones Tonicity Activated by low blood volume, triggers release of renin which converts angiotensinogen to angiotensin I. ACE converts angiotensin I to angiotensin II which causes arterial vasoconstriction and stimulates release of aldosterone. Aldosterone stimulates renal Na reabsorption and K+ excretion. Water is retained, less urine is produced, blood volume increases. ANP and BNP- released by heart- works opposite RAAS to decrease blood volume, promotes urinary excretion of Na and water Tonicity is the effective osmolality of a solution. Effective osmolality is the concentration of those solutes that do not readily cross the cell membranes and in effect contribute to the osmolality. Even though urea is a solute in the plasma it freely diffuses through the cell membranes and has no effect on osmolality, whereas sodium and glucose are If blood flow to the kidneys diminishes (hemorrhaging) or sodium level drops renin is secreted. Renin causes vasoconstriction and increase in BP. If blood flow increases, less renin secreted reduces vasoconstriction and helps normalize blood pressure. -suppresses serum renin levels -decreases aldosterone release from the adrenal glands -increases glomerular filtration, which increases urine excretion of sodium and water - decreases ADH release from the posterior pituitary gland -reduces vascular resistance by causing vasodilation Anything that causes atrial stretching can lead to increases in the amount of ANP released, including orthostatic changes, atrial tachycardia, high sodium intake, sodium chloride infusions and use of drugs that cause vasoconstriction Tonicity is important when correcting water and solute imbalances by administering different types of replacement solutions. orthostatic changes, atrial tachycardia, high sodium intake, sodium chloride infusions and use of drugs that cause vasoconstriction Tonicity Isotonic Hypotonic Tonicity is the effective osmolality of a solution. Effective osmolality is the concentration of those solutes that do not readily cross the cell membranes and in effect contribute to the osmolality. Even though urea is a solute in the plasma it freely diffuses through the cell membranes and has no effect on osmolality, whereas sodium and glucose are limited to the extracellular space and greatly contribute to the effective osmolality. Tonicity and osmolality may be used interchangeably. Of a fluid that exerts the same OSMOTIC PRESSURE as another, especially as that of the body fluids. Body cells, such as red blood cells, can be immersed in an isotonic solution without being caused to change shape. ‘Normal’ saline is isotonic with blood. Has the same osmolality or concentration of particles as the ICF or ECF. Administration of a hypotonic intravenous solution will cause the intravascular space to become more dilute (less solute concentration and a lower osmolality). Based on the concept of osmosis, water will move from the intravascular space to the extracellular space. This will cause a dilution of the extracellular space causing water to then shift into the intracellular space, consequently causing the cell to swell or burst. A hypertonic IV solution, when administered, will increase the solute concentration in the Tonicity is important when correcting water and solute imbalances by administering different types of replacement solutions. Diarrhea is a loss of isosmotic fluid from the GI tract Examples of isotonic IVF: -Lactated Ringers -0.9% Nacl -D5 0.225% Nacl Water is a hypotonic solution. Water is osmotically pulled in cells, causing them to swell or burst. IV Fluid: -0.45% sodium chloride Aka 0.45%NaCl or 0.45% NS (1/2ns) -0.33% NaCl or ).33% NS Example of hypertonic IVF: 3% saline solution. Water is pulled out cell by hypertonic Hypotonic Hypertonic Diffusion to change shape. ‘Normal’ saline is isotonic with blood. Has the same osmolality or concentration of particles as the ICF or ECF. Administration of a hypotonic intravenous solution will cause the intravascular space to become more dilute (less solute concentration and a lower osmolality). Based on the concept of osmosis, water will move from the intravascular space to the extracellular space. This will cause a dilution of the extracellular space causing water to then shift into the intracellular space, consequently causing the cell to swell or burst. A hypertonic IV solution, when administered, will increase the solute concentration in the intravascular space. The intravascular space will become more concentrated and will experience an increased osmolality. Concentration is more than 285 to 294 mOsm/kg. The passive movement of molecules or particles along a concentration gradient, or from regions of higher to regions of lower concentration -Lactated Ringers -0.9% Nacl -D5 0.225% Nacl Water is a hypotonic solution. Water is osmotically pulled in cells, causing them to swell or burst. IV Fluid: -0.45% sodium chloride Aka 0.45%NaCl or 0.45% NS (1/2ns) -0.33% NaCl or ).33% NS Example of hypertonic IVF: 3% saline solution. Water is pulled out cell by hypertonic so cells shrink, -D10W -3& or 5% NaCl -D5 NS -D5 0.45% NaCl c. Evaluate the purpose, function and role of hydrostatic and oncotic pressure and describe the mechanisms by which they are altered. Mechanisms by Which They Purpose/Function/Role are Altered Increased Hydrostatic Venous obstruction: Pressure -Tight clothing 1. venous obstruction or retention of Na and water → -Increased standing Hydrostatic Pressure -Venous blood clots ↑ hydrostatic Retained Na & H2O: pressure → fluid is pushed out of the vascular space into -CHF -Renal failure the interstitial space. Decreased production of plasma proteins Decreased oncotic pressure -Liver disease/ cirrhosis 1. Decreased plasma protein Purpose/Function/Role Mechanisms by Which They are Altered Hydrostatic Pressure Increased Hydrostatic Pressure 1. venous obstruction or retention of Na and water → ↑ hydrostatic pressure → fluid is pushed out of the vascular space into the interstitial space. Venous obstruction: -Tight clothing -Increased standing -Venous blood clots Retained Na & H2O: -CHF -Renal failure Oncotic Pressure Decreased oncotic pressure 1. Decreased plasma protein → decreased oncotic pressure and osmotic pressure → fluid moves into the interstitium Decreased production of plasma proteins -Liver disease/ cirrhosis -Protein malnutrition Protein wasting -Glomerular disease -Trauma, hemorrhage, burns Acid Base Balance 2. Analyze how the body maintains optimal pH balance. a. Explain the role of the components of the chemical buffer system in acid base balance and describe the implications for clinical practice. · Bicarbonate: Bicarbonate (HCO3-/CO2 Buffer) is the most important extracellular buffer. It is the first line of defense against alterations in the acid base balance. Operates in the lung and the kidney. If bicarbonate is decreased the pH will decrease and cause acidosis. In this buffer system carbonic acid (H2CO3) is increased and bicarbonate (HCO3) is decreased. The lungs help decrease carbonic acid by exhaling CO2, the kidneys help reabsorb bicarbonate or generate new bicarbonate from CO2 & water. Respiratory compensatory response can occur rapidly within minutes to hours by increasing or decreasing the respiratory rate. The renal compensatory response can take longer, between several hours or days, to produce more acidic or more alkaline urine. · Phosphates: phosphates can be either inorganic or organic. • Inorganic phosphate is an extracellular buffer. HPO4 (dibasic phosphate) combines with secreted H+ → forming H2PO4 (monobasic phosphate) H2PO4 contains the H+ and is excreted in urine • Organic phosphates operate as intracellular buffers • ATP • ADP • AMP • Glucose • 1-phosphate • 2,3 diphosphoglycerate (2,3 DPG) · Plasma Proteins: Plasma Proteins act as extracellular buffers. • Main plasma protein is Albumin • Carries a negative charge which allows it to buffer H+ (because it carries a positive charge) • Albumin plays a role in binding ~40% of calcium • During acidosis, excess hydrogen ions bind to albumin which in turn deters albumin from being able to bind with calcium. Calcium ions are displaced, and results in high levels of free calcium. • During alkalosis, insufficient hydrogen ions are available to bind with albumin. This causes albumin to bind with more calcium than usual and results in diminished levels of free calcium. · Hemoglobin: Hemoglobin is the most important intracellular buffer and plays a pivotal role in acid base homeostasis. Behave chemically as bicarbonate buffers. Less saturated hemoglobin (venous blood) is a better buffer than hemoglobin saturated with oxygen (arterial blood). • After hemoglobin delivers oxygen to the tissues, it absorbs CO2 and transports it back to the lungs to be expired. **Chemical buffers prevent sudden changes in the pH balance. If chemical buffers are unable to maintain the pH, then the lungs will begin to compensate within a minute or two. If the lungs are ineffective, the kidneys will begin to compensate in approximately 24 hours. The lungs remove 30Liters of carbonic acid from venous blood on a daily basis. b. Describe the normal pH balance, the source and type of metabolic acids, and their clinical significance. • · Normal pH: 7.35-7.45 Metabolic Acids o Carbonic Acid: Carbonic acid is a weak acid that is created when carbon dioxide (CO2) is dissolved in water (H2O), resulting in the chemical formula H2CO3. When the acid dissociates, or gives up a hydrogen ion, the resulting molecule is called a bicarbonate ion. o Lactic Acid: The cells in your body make lactic acid when they don't have a lot of oxygen to use. This acid can build up, too. It might happen when you're exercising intensely. Big drops in blood pressure, heart failure, cardiac arrest, and an overwhelming infection can also cause it. o Sulfuric Acid: Nonvolatile, strong acid. Results from the oxidation of sulfur containing amino acids. o Phosphoric Acid: Nonvolatile, strong acid. Results from metabolism of phosphoproteins and ribonucleotides which are used as an energy source. Phosphoric acid is made from the mineral phosphorus, which is found naturally in the body. It works with calcium to form strong bones and teeth. It also helps support kidney function and the way your body uses and stores energy. Phosphorus helps your muscles recover after a hard workout. The mineral plays a major role in the body’s growth and is even needed to produce DNA and RNA, the genetic codes of living things. o Ketone Bodies: are three water-soluble molecules (acetoacetate, beta-hydroxybutyrate, and their spontaneous breakdown product, acetone) that are produced by the liver from fatty acids[1] during periods of low food intake (fasting), carbohydrate restricted diets, starvation, prolonged intense exercise,[2] or in untreated (or inadequately treated) type 1 diabetes mellitus. These ketone bodies are readily picked up by the extrahepatic tissues, and converted into acetyl-CoA which then enters the citric acid cycle and is oxidized in the mitochondria for energy.[3] In the brain, ketone bodies are also used to make acetylCoA into long-chain fatty acids. c. Analyze the formula which represents acid base balance and describe the implications for clinical practice. CO2 + H2O H2CO3 H+ + HCO3Occurs in the lungs Occurs in the kidney Body acid exists in two forms: volatile (Respiratory acids--eliminated as CO2) and nonvolatile (metabolic acidosis --eliminated by the kidney or metabolized by liver). A loss of a hydrogen ion will shift equation to the right. The lungs retain more CO2 to convert it into carbonic acid (H2CO3), which will then convert into hydrogen ions and bicarb. A hydrogen ion gain results in the equation shifting left. Lungs are stimulated to increase ventilation in effort to expel more CO2. Carbonic anhydrase either adds water to CO2 and makes H2CO3, or dissociates water from CO2 and breaks down H2CO3 to CO2 and H2O (p.123 & Acid Base Balance notes). Implication: The renal and respiratory systems, together with the body’s buffer systems, are the principal regulators of acid base balance. d. Explain the three roles of the kidney in the maintenance of acid base imbalance and describe the implications for clinical balance. Role of Kidney Definition Clinical Implications When the extracellular fluid volume is expanded it inhibits the reabsorption of bicarbonate in the proximal This is what causes a tubule. A deficit in the metabolic alkalosis (also extracellular fluid volume called contraction alkalosis) results in an increase in the secondary to volume Reabsorption of Bicarbonate reabsorption of HCO3-. ECF depletion. This can also occur volume deficit also stimulates with the use of loop and the renin-angiotensin system. thiazide diuretics. Treatment Angiot...
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