Chapter 17 Fluid Electrolytes and Acid-B

8/2/2019 Chapter 17 Fluid Electrolytes and Acid-B

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CChhaapptteerr 1177 FFlluuiidd,, EElleeccttrroollyytteess aanndd AAcciidd--BBaassee IImmbbaallaanncceessJulie S. Brinley, RN, MSN/Ed, CNE

Objectives

Describe the composition of the major body fluid compartments.Define the processes involved in the regulation of movement of water and electrolytes

between the body fluid compartments: diffusion, osmosis, filtration, hydrostatic pressure,oncotic pressure, and osmotic pressure.

Describe the etiology, laboratory diagnostic findings, clinical manifestations, and nursing andcollaborative management of the following disorders:

Extracellular fluid volume imbalances: fluid volume deficit and fluid volume excess Sodium imbalances Potassium imbalances Magnesium imbalances Calcium imbalances Phosphate imbalances

Identify the processes to maintain acid-base balances.Describe the etiology, laboratory diagnostic findings, clinical manifestations, and nursing and

collaborative management of the following disorders:

Metabolic acidosis Metabolic alkalosis Respiratory acidosis Respiratory alkalosis

Describe the composition and indications of common intravenous fluid solutions.Homeostasis is a term used to describe stability or equilibrium.Proper fluid and electrolyte balance in the body is regulated by fluid and electrolyte

transport systems and regulatory mechanisms such as hormones and body organs.

Physical and biologic processes work together to maintain a balance or equilibrium.


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Homeostasis

The state of equilibrium in the internal environment of the bodyBody fluids and electrolytes play an important role in homeostasisAcids are produces in the body during normal metabolismAcids alter internal environment in the body

Fluids and electrolytesDiseases and treatments can alter fluid and electrolyte balanceStarlings Law

Equilibrium exists at the capillary membrane when fluid leavingcirculation and the amount of fluid returning to circulation areexactly equal.

Water is Vital

Water is necessary as a medium for metabolic reactions within cells a transporter for nutrients, waste products and other substances a lubricant an insulator and shock absorber a means of regulating and maintaining body temperature a medium for food digestion

Fluid IntakeFactors Affecting Body Fluid

Age Gender and body size Pregnancy(blood volume increase) Ethnic origin Environmental temperature Life style

Exercise Stress Alcohol consumption


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Age Percentage of fluid

Newborn (full term) 70-80%1 year 64%Puberty to 39 52-60%

40-60 47-55%Over 60 46-52%

Factors Affecting Body Fluid

Infants percentage of total body water is extracellular Basil metabolic rate Body surface area

(larger volume of fluid loss throught skin)

Fluid requirements Immature kidney function (inability to concentrate urine)

Elderly percentage of body fluids intracellular fluid volume thirst Self-limiting of fluids ability to conserve water renal blood flow and glomerular filtration

What effect does obesity have on body water percentage?

An obese person would have a lower percentage of total body water.

Muscle contains much more water than body fat which is essentially free of water.

Women have more body fat than men.

Anatomy and Physiology

Body Fluids Most important nutrient Humans can survive only a few days without water


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ElectrolytesA solution of a compound that dissociates into ions and can conduct electricity. Electrolytes

affect the movement of substances between body fluids and tissues, and are crucial for normalfunction and metabolism

Fluid and Electrolyte Movement Exchange results in fluid balance and homeostasis that is essential to lifeWater

Major component of the blood - 60% of total body weight of an adult is water 92% of bodys organic and inorganic compounds are dissolved in water Solute the thing being dissolved

Solvent

does the dissolving

Solutions are made up of: FLUID (solvent) primarily water P ARTICLES DISSOLVED (solute) electrolytes (K, Na, Cl), nonelectrolytes (urea)

Body Fluid Compartments

Intracellular (ICF) 40 % of body weightExtracellular (ECF) -20 % of body weight

Interstitial (ISF) 15% of body weight Lymph Dense connective tissue bone

Intravascular (IVF) 5 % of body weightTranscellular (TCF) 1 % of body weight

Pleura peritoneum

Distribution of Fluid

Extracellular - outside the cells. Intravascular - within the vascular system (plasma). system Interstitial fluid - surrounds the cells and includes lymph Transcellular - CSF, digestive, pleural, peritoneal and synovial fluids.


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Calculation of Fluid Gain or Loss

1 liter of water = 2.2 Lb (1kg)Example= pg 303

If a patient on diuretic therapy loses 6.3 lbs in 24 hours How much fluid has he lost? How much fluid would a person drink in a day? How much fluid would a person loose in a day?

Electrolytes

Substances that split into ions that are electrically charged particles Catoins (positive charged)Anions (negatively charged)What are some examples?How are they measured and from where?

Measured in the blood plasma

Mechanisms Controlling Fluid and Electrolyte Movement

DiffusionFacilitated diffusionActive transportOsmosis

Osmosis Osmotic pressure osmolality

Hydrostatic PressureOncotic pressureFluid and Electrolyte Transport Systems

Movement of f luid & electrolytes Passive transport

Diffusion Osmosis Filtration


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Active transport requires energy as a force to move molecules into the cells against theconcentration gradient. Active transport moves fluid and electrolytes from an area of lowerconcentration to an area of higher concentration

The rate of diffusion depends on the size of molecules,the concentration of solution and the temperature.

Facilitated Diffusion

A carrier molecule facilitates the rate of diffusionExample:

glucose requires insulin to be transported or facilitated into cellsActive Transport

Molecules move against the concentration gradientEnergy is requiredExample:

Solium / potassium pumpFluid and Electrolyte Transport Systems

Fluid and Electrolyte Transport Systems

Osmotic PressureThe power of the solution to draw water across a semi permeable membraneTypes of IV Fluids

IsotonicHypotonichypertonicPressures That Affect Fluid Movement

Hydrostatic pressure The force within a fluid compartment

Oncotic pressure (colloidal osmotic pressure) is osmotic pressure exerted by colloids in a solutionFluid Movement

The amount and direction of movement are determined by the interaction of : Capillary hydrostatic pressure Plasma oncotic pressure


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Interstitial hydorstatic pressure Interstitial oncotic pressure

Fluid Spacing

Term used to describe the distribution of body water First spacing normal Second spacing edema Third spacing fluid trapped and unavailable for functional use ie

Peritonitis Burn trauma edema sepsis

How is Water Balance Regulated?

Hypothalamic regulationPituitary regulationAdrenal cortical regulationRenal regulationCardiac regulationGastrointewstional regulation

Insensible water lossThirst

Regulates fluid intakeIncreased plasma osmolality stimulates osmoreceptors in the hypothalamus to

trigger the sensation of thirst

More sodium and less water in the body make a person thirstyAdditional fluids consumed; kidneys conserve water until osmolality returns to

normalHypothalamic, Pituitary, and Adrenal Cortical Regulation

ThrustADH regulated water retention by the kidneys -causes reabsorptionADH (vasopressin) suppression causes urinary excretion


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Corticoids - enhance sodium retention and water follows sodiumAldosterone is potent sodium retaining capabilities

Is stimulated by decreased renal perfusionHormones

Renin Hormone secreted when blood volume or blood pressure falls Causes the release of aldosterone with subsequent sodium and water retentionAldosteroneActs on kidney tubules to increase reabsorption of sodium and decrease reabsorption of

potassium

Because the retention of sodium causes water retention, aldosterone acts as a volume regulatorCardiac Regulation

ANP atrial natriuretic peptideBNP b-type natriuretic peptide

Produced in cardiac cells Respond to increased B/P and high sodium levels Suppress secretion of aldosterone, renin, and ADH Promote excretion of Na+ and water

Hormones

Antidiuretic hormone (ADH) Causes capillaries to reabsorb more water, so urine is more concentrated and less volume is

excreted

Atrial natriuretic factor (ANF) Hormone released by the atria in response to stretching of the atria by increased blood volume Stimulates excretion of sodium and water by the kidneys, decreased synthesis of renin,

decreased release of aldosterone, and vasodilation

Reduces blood volume and lowers blood pressure


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Gastrointestional Regulation

Food metabolism produced waterExcretion of waterAbsorption of water in GI tractDiarrhea or vomiting

Leads to significant fluid and electrolyte imbalancesRegulators of Fluids & Electrolyte Balance

Skin estimated water loss 300-400 cc/day called Insensible Loss Lungs Insensible water loss due to expired air saturated with water vapor is 300-400 cc/day GI System 8,000 cc /day is secreted into GI tract and about 200cc is lost through feces. Severediarrhea can cause fluid and electrolytes imbalance Kidneys 1,200-1,500 cc water per day as urine Fluid and food intake water consumption and obtained from food Thirst water consumption is in response to the sensation of thirstIntake & Output

Fluid and Electrolyte ImbalancesEffects most patients with a major illness or injuryClassified as deficits or excessOccurs in the intravascular spaceAssessment of Fluid and

Electrolyte Balance

Health historyDetermines if patient has conditions that contribute to fluid or

electrolyte imbalances Like What???


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Complaints of fatigue, palpitations, dizziness, edema, muscleweakness or cramps, dyspnea, and confusion may be associated withfluid imbalances

Vital signsIntake and outputSkin

Characteristics

Facial characteristics

Skin turgorEdemaDependent Edema

Found in the lowest parts of the body such as in the feet and legs and sacrum of the sitting client. Edema can belocalized or generalized in the body and can increase weight by at least 10 lb

Frequently observed around eyes, and in the feet and handsMucous membranes

Tongue turgor Moisture of the oral cavityVeins


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Fluid Volume Deficit

AKA DehydrationHypovolemia

Caused by:Abnormal loss through skin, GI or kidneysBleedingThird spacingFluid Imbalances

Deficient fluid volume Less water than normal in the body Isotonic extracellular fluid deficit Hypovolemia Hypertonic extracellular fluid deficit

DehydrationDecreased intake, abnormal f luid losses, or bothExamples: loss of water from excessive bleeding, severe vomiting/diarrhea, severe

burns

Risk For Fluid Volume Deficit

VomitingDiarrheaSuctionDrainage of secretionsAnorexia Inability to swallow, confusion, DepressionFluid Volume Deficit (Hypovolemia)

Signs and Symptoms Poor skin turgor Dry mucous membranes, dry furrowed tongue Tachycardia


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Narrowing pulse pressure Decreased central venous pressure Postural hypotension Flat neck veins urinary output, specific gravity Hemoconcentration ( hematocrit, BUN)

Fluid Imbalances

Excess f luid volumeAn increase in body water

Extracellular fluid excess Isotonic fluid excess

Intracellular water excess Hypotonic fluid excess

From renal or cardiac failure with retention of fluid, increased production of antidiuretichormone or aldosterone, overload with isotonic IV fluids, or administration of dextrose 5% in

water (D5W) after surgery or trauma

Fluid Volume Excess

Excessive IV therapyExcessive ingestions of sodium salts, Alka-Seltzer, hypertonic enemas,CHF, liver failure, renal failureBody retains both water and sodiumHypervolemia-increased blood volumeCaused by excessive intake of NaIV infusions infused to quicklyDisease, liver, CHF, renal


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Fluid Volume Overload (Hypervolemia)

Signs and Symptoms Bounding pulses Distended neck veins Increased BP Increased CVP Dyspnea EdemaWeight gain Decreased hematocrit and hemoglobin

Fluid ExcessWEIGHT GAIN

2% gain-mild

5% gain-moderate

8% gain-severe

Monitoring

Daily weightsSignificant changes in a short period of time are indicative of acute fluid changesWeigh at the same time, same clothes, same scaleTreatment

Loop diuretics act in the loop of Henle. They are the most powerful of diuretics, capable of causing 15-25% of thesodium in the filtrates to be excreted. This can cause serious potassium loss. Can be given orally or IV

Patient may be given a loop diuretic such as lasix. Watch for postural hypotension.Restricted Fluids

May be necessary for pts with fluid volume excess from renal failure, CHF, or otherdisease process.

You might want to give the patient hard candy.


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ElectrolytesHyponatremiaCauses:

GI and Renal loss Profuse perspiration,draining skin lesions Fibrocystic disease of the pancreas Diuretics Relative sodium loss in fluid overload (water toxicity) Post surgery when pt losses blood and other fluids

Assessment

Postural blood pressure change

Poor skin turgor Flat neck veins Hypotension with rapid thready pulse, cooled clammy skin Headache, faintness, mental confusion, muscle crampsHypernatremiaCauses:

Inadequate water intake or excessive water loss

Diminished thirst response especially in elderly and infants TPN and tube feeding may deplete the cells of water

Assessment:

Changes in neuromuscular and cardiac activity Changes in personality: agitation and confusion, later seizures and death Skeletal muscle weakness Decreased myocardial contractibility resulting in decreased cardiac output Death may occur as a result of excessive rise in osmotic pressure and respiratory arrestPotassium (K+) - 3.5 5.0 mEq/LMajor intracellular electrolyte

Maintains normal nerve and muscle activity (especially cardiac). Maintains osmotic


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pressure in the cell.

Hypokalemia GI disturbances, diuretic therapy.Needs KCl replacement.

Hypokalemia potentiates digitoxicity. Hyperkalemiarenal disease, excessive trauma, inhibits theaction of digitalis with major cardiac effects (Cardiac arrest)

HypokalemiaCauses:

Increased renal loss by using excessively diuretic therapy GI loss through N&V Insufficient potassium intake Potassium cannot be stored it should be ingested daily

Assessment:

Early signs as fatigue, lack of strength Muscular weakness: paralysis, ventilation problems, Bradycardia, atrial dysrhythmias Late signs: tetany and loss of deep tendon reflexes Depression Death is caused by anoxia from paralysis of the respiratory muscles and cardiac arrestHyperkalemia

Causes:

Renal disease K cannot be excreted adequatelyAddisons disease Crushing injuries with muscular destruction Metabolic acidosis (shift potassium from ICF to ECF)

Assessment

Neuromuscular irritability (similar to hypokalemia)Vague muscle weakness leading to paralysis Pt. remains alert and conscious until cardiac arrest occur Death results in the toxic state from cardiac dysrhythmias (VF or atrial standstill)


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Food sources for Potassium:

Beef (4oz) 400

Avocado (medium) 1000Bananas (1 medium) 451Mushrooms (10 small) 410Spinach raw (3oz) 470Tomato (1medium) 366Education

Do not substitute one potassium supplement for another

Do not crush potassium tablets such as Slow-K or K-tab Do not use salt substitute that contained KCl Take Potassium supplements with mealsCalcium (Ca++)

Essential role in bone structure blood clotting, muscle contraction and nerve impulsetransmission.

HypocalcemiaPositive for Chvosteks sign & Trousseaus SignHypercalcemiasign of metastatic bone tumor, Pagets disease, hyperparathyroidismSigns of HypocalcemiaChvosteks signs

Tapping on the face at a point just anterior to the ear and just below the zygomatic bone Positive response: Twitching of the ipsilateral facial muscles, suggestive of neuromuscular excitability caused by Hypocalcemia Trousseau's sign

Inflating a sphygmomanometer cuff above systolic blood pressure for several minutes Positive response: Muscular contraction including flex-ion of the wrist and metacarpophalangeal joints, hyperextension of the fingers, and flexion of the thumb

on the palm, suggestive of neuromuscular excitability caused by hypocalcemia


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Phosphate (PO4) 2.8mg/dl4.5mg/dl

Phosphorus is a primary anion in the ICF and is essential to the function of muscle, RBCs,and the nervous system.

It is deposited with calcium for bone and tooth structure.Phosphorus is also involved in the acid base buffering system, the mitochondrial energy

production of ATP, cellular uptake and use of glucose, and the metabolism of carbohydrates,proteins, and fats.

Maintenance of normal phosphate balance requires adequate renal functioning because thekidneys are the major route of phosphate excretion.

A reciprocal relationship exists between phosphorus and calcium in that a high serumphosphate level tends to cause a low calcium concentration in the serum.

Hyperphosphatemia is caused by acute or chronic renal failure that results in an alteredability of the kidneys to excrete phosphate.Other causes include;

Chemotherapy for certain malignancies (lymphomas) Excessive ingestion of milk or phosphate containing laxatives. Large intake of vitamin D that increase GI absorption of phosphorus.

Wound of a 55 yr old with Hx of HyperphosphatemiaClinical manifestations primarily relate to metastatic calcium and phosphate precipitates.Ordinarily, calcium and phosphate are deposited only in bone.An increased serum phosphate concentration along with calcium precipitates readily, and

calcified deposits can occur in soft tissue such as joints, arteries, skin, kidneys, and corneas.

Clinical manifestations also include; neuromuscular irritability and tetany, which are relatedto low serum calcium levels.

Management includes; Identifying cause Restrict foods and fluids high in phosphorus (dairy products)Adequate hydration Correct hypocalcemia (as calcium levels increase phosphorus is excreted thru the kidneys.

Lung of patient with lymphoma and HyperphosphatemiaHypophosphatemia is seen in patients with malnourishment or has malabsorption syndrome.


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Other causes are alcohol withdrawal and use of phosphate binding antacids.Because phosphorus is needed for formation of ATP and 2,3, DPG, its deficit results in

impaired cellular energy and oxygen delivery.

Other clinical manifestations include muscle weakness and pain dysrhythmias, andcardiomyopathy.Management includes oral supplementation (Nutra-Phos) and ingestion of foods high in

phosphorus (dairy products).

Magnesium (1.3-2.1 mg/dl)

Magnesium is the second most abundant intracellular cation.Approximately 50% to 60% of the bodys magnesium is contained in bone. If functions as a co-enzyme in the metabolism of carbohydrates and protein. It is also involved in metabolism of cellular nucleic acids and proteins.Magnesium is regulated by GI absorption and renal excretion.The kidneys are able to conserve magnesium in times of need and excrete excesses.Factors that regulate calcium balance (PTH) appear to similarly influence magnesium

balance.

Because magnesium balance is related to calcium and potassium balance. All three cationsshould be assessed together.Magnesium acts directly on the myoneural junction, and neuromuscular excitability is

profoundly affected by alterations in serum magnesium levels.

Hypomagnesaemia produces neuromuscular and CNS hyperirritability.Hypermagnesemia depresses neuromuscular and CNS functions.Magnesium is important for normal cardiac function.There is an association between hypomagnesaemia and cardiac dysrhythmias.Hypermagnesemia usually occurs only with an increase in magnesium intake accompanied

by renal insufficiency or failure.

Clinical manifestations; Lethargy, drowsiness, and nausea and vomitingAs the levels increase, deep tendon reflexes are lost, followed by somnolence, and then


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respiratory and ultimately, cardiac arrest.

Rx should focus on prevention. Emergency treatment for Hypermagnesemia is IV administration of calcium chloride or calcium

gluconate to physiologically oppose the effects of the magnesium on cardiac muscle.

The major cause of hypomagnesaemia is prolonged fasting or starvation.Chronic alcoholism commonly causes hypomagnesaemia as a result of insufficient food

intake.

Fluid loss from the GI tract interferes with magnesium absorption.Another cause is prolonged TPN without magnesium supplementation.Osmotic diuresis caused by high glucose levels in uncontrolled DM increases renal excretion

of magnesium.

Clinical manifestations include; Confusion, hyperactive deep tendon reflexes, tremors, and seizures. It also predisposes to dysrhythmias.

Acid - Base Imbalances

AcidsBasesBuffersBuffer systems

Hemoglobin systemPlasma protein systemCarbonic acid-bicarbonate system

Hemoglobin System

RBSs contain hemoglobinChloride shift


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Chloride shifts in and out of cells in response to the level of O2 in theblood

For each Cl- that leaves a RBC a HCO3- entersFor each Cl- that enters a RBC a HCO3- leavesPlasma protein system

Functions along with the liver to vary the amount of H- in thechemical structure of plasma proteins

Plasma proteins have the ability to attract or release H- ions

Carbonic acid-bicarbonate system

Primary buffer system in the bodyIs controlled by the lunges by the excretion of CO2-

The kidneys control the bicarbonate concentration and selectively retainor excrete bicarbonate in response to body needs

Acid-Base Control

Lungs

Kidneys

Potassium


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Respiratory Acidosis

Respiratory system fails to eliminate the appropriate amount of carbon dioxide tomaintain the normal acid-base balance

Caused by pneumonia, drug overdose, head injury, chest wall injury, obesity,asphyxiation, drowning, or acute respiratory failureMedical treatment

Improve ventilation, which restores partial pressure of carbon dioxide in arterial blood (Paco2)to normal

Nursing careAssess Paco2 levels in the arterial blood Observe for signs of respiratory distress: restlessness, anxiety, confusion, tachycardia

Intervention Encourage fluid intake Position patients with head elevated 30 degrees

Respiratory Alkalosis

Low Paco2 with a resultant rise in pH Most common cause of respiratory alkalosis is hyperventilation Medical treatment Major goal of therapy: treat underlying cause of condition; sedation may be ordered for the anxious

patient

Nursing care Intervention

In addition to giving sedatives as ordered, reassure the patient to relieve anxiety Encourage patient to breathe slowly, which will retain carbon dioxide in the body


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Metabolic Acidosis

Body retains too many hydrogen ions or loses too many bicarbonate ions; with toomuch acid and too little base, blood pH falls

Causes are starvation, dehydration, diarrhea, shock, renal failure, and diabeticketoacidosisSigns and symptoms: changing levels of consciousness, headache, vomiting and

diarrhea, anorexia, muscle weakness, cardiac dysrhythmias

Medical treatment: treat the underlying disorderNursing care

Assessment of the patient in metabolic acidosis should focus on vital signs, mental status, andneurologic status

Emergency measures to restore acid-base balance. Administer drugs and intravenous fluids asprescribed. Reassure and orient confused patientsMetabolic Alkalosis

Increase in bicarbonate levels or a loss of hydrogen ionsLoss of hydrogen ions may be from prolonged nasogastric suctioning, excessive

vomiting, diuretics, and electrolyte disturbances

Signs and symptoms: headache; irritability; lethargy; changes in level ofconsciousness; confusion; changes in heart rate; slow, shallow respirations withperiods of apnea; nausea and vomiting; hyperactive reflexes; and numbness of theextremities

Medical treatment Depends on the underlying cause and severity of the condition

Nursing careAssessment

Take vital signs and daily weight; monitor heart rate, respirations, and fluid gains and losses Keep accurate intake and output records, including the amount of fluid removed by suction Assess motor function and sensation in the extremities; monitor laboratory values, especially pH andserum bicarbonate levels

Intervention To prevent metabolic alkalosis, use isotonic saline solutions rather than water for irrigating

nasogastric tubes because the use of water for irrigation can result in a loss of electrolytes

Provide reassurance and comfort measures to promote safety and well-being


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ROME for Acid-Base

Respiratory Opposite

Metabolic Equivalent

Documents

Chapter 17 Fluid Electrolytes and Acid-B