Presentation on theme: "Alterations in Fluid, Electrolyte and Acid-Base Balance in Children"— Presentation transcript:
1Alterations in Fluid, Electrolyte and Acid-Base Balance in Children Dr. Nataliya Haliyash, MD, BSNInstitute of Nursing, TSMU
2Pediatric Differences ECF/ICF ratio varies with ageNeonates and infants have proportionately larger ECF volumeInfants: high daily fluid requirement with little fluid reserve; this makes the infant vulnerable to dehydration.
4Fluid Loss; Infants and <2yr. excretion is via the urine, feces, lungs and skinhave greater daily fluid loss than older childmore dependent upon adequate intakegreater about of skin surface (BSA), therefore greater insensible loss.respiratory and metabolic rates are highertherefore, dehydrate more rapidly
5Mechanism to Restore balance kidney: conserves water, regulates electrolyte excretion<2yr kidneys immatureless able to conserve or excrete water and solutes effectivelygreater risk for acid/base imbalancesWill use the SG norm:
6Fluid Volume Imbalances Dehydration: loss of ECF fluid and sodium.Caused by: vomiting, diarrhea, hemorrhage, burns, NG suctioning and drainage loss, adrenal insufficiency.Manifested by wt loss, poor skin turgor, dry mucous memb., VS changes, sunken fontanelDehydration that is not corrected will lead to hypovolemic shock and death.Fluid overload: excess ECF fluid and excess interstitial fluid volume with edema.Causes: fluid overload, CHF.Manifested by wt.gain, puffy face and extremities, enlarged liver.
7Clinical Manifestations of Dehydration Depend on the degree of dehydration.Weight lossRapid-thready pulseHypotensionDecreased peripheral circulationDecreased urinary outputIncreased specific gravitydecreased skin turgordry mucous membranesabsence of tearsa sunken fontanel in infants.
8Nursing Considerations How can the nurse determine if the child is mildly dehydrated vs moderately dehydrated?
9Mild Dehydration: by history. hard to detect because the child may be alert, have moist mucous membranes and normal skin turgor.Wt loss may be up to 5% of body weight.The infant might be irritable; the older child might be thirstyvital signs will probably be normalCapillary refill will most likely be normalUrine output may be normal or sl less
10Moderate Dehydrationdry mucous membranes; delayed cap refill >2 sec; Wt loss 6-9% of body weightirritable, lethargic, unable to play, restlessdecreased urinary output: <1ml/kg/hr; dark urine with SG > (in child >2yr)Sunken fontanelHR increased, BP decreased. Postural vital signs
11Severe Dehydration wt loss > 10% body weight lethargic/comatose rapid weak pulse with BP low or undetectable; RR variable and labored.dry mucous membranes/parched; sunken fontaneldecr or absent urinary output.Cap refill >4sec
12Types of Dehydration and Sodium Loss Sodium may be:LowHighOr normal
13Isotonic Dehydration or Isonatremic Dehydration Loss of sodium and water are in proportionMost of fluid lost is from extracellular componentSerum sodium is normal ( mEq/L) Harriet Lane Handbook, 2000.Most practitioners consider below 135 and above 148 a more conservative parameter ( )Most common form of dehydration in young children from vomiting and diarrhea.
14Hypotonic or Hyponatremic Dehydration Greater loss of sodium than waterSerum sodium below normalCompensatory shift of fluids from extracellular to intracellular makes extracellular dehydration worse.Caused by severe and prolonged vomiting and diarrhea, burns, renal disease. Also by treatment of dehydration with IV fluids without electrolytes.
15Hypertonic or Hypernatremic Dehydration Greater loss of water than sodiumSerum sodium is elevatedCompensatory shift from intracellular to extracellular which masks the severity of water loss (dehydration) delaying signs and symptoms until condition is quite serious.Caused by concentrated IV fluids or tube feedings.
16Clinical Manifestations Associated with Degree of Dehydration
18Nursing DiagnosesNursing diagnoses appropriate for a child with dehydration may include:1. Deficient fluid volume related to excessive fluid volume loss or inadequate fluid intake.2. Risk for injury (fall) related to orthostatic (postural) hypotension.3 . Deficient knowledge (caregiver) related to lack of exposure to information about preventing/detecting dehydration.
19Outcome Identification 1. The child will receive sufficient fluids to replace losses.2. The child will exhibit signs of adequate hydration.3. The child will not fall or sustain other injuries while hypotensive or lethargic.4. Caregivers will demonstrate understanding of conditions that can lead to dehydration and of the early signs and symptoms.
20Planning/Implementation Nursing interventions include:assessment of daily weight, vital signs, and maintenance of accurate intake and output records.Blood may be drawn to assess electrolytes, BUN and Creatinine levelsadministration of oral or IV fluids.Injury due to falls can be prevented by making sure that the side rails of the bed are raised, assessing level of consciousness, and monitoring the serum sodium level.An elevation in serum sodium will cause the brain cells to dehydrate and result in a loss of consciousness if not corrected quickly.
21Diarrheais increase in the number of stools and/or a decrease in their consistency as a result of malabsorption or alterations of water and electrolyte transport by the alimentary tract.Diarrhea may be acute or chronic.
22Grades of diarrheaMild diarrhea – 4 to 7 loose stools each day as a rule without other evidence of illnessModerate diarrhea – 8 to 15 loose or watery stooles daily with elevated temperature, vomiting, irritability, mild dehydrationSevere diarrhea – numerous (>15) to continuous stools, evident signs of moderate to severe dehydration, drawn, flaccid expression, high pitched cry, irritable or lethargic or even comatose.
23Acute gastroenteritis is characterized by the passage of ≥3 loose or watery stools in an 24 hour period, or the passage of one or more bloody stools, with or without vomiting, nausea, fever, and abdominal pain.Acute gastroenteritis usually refers to as an illness lasting no longer than days.
26Pathogenesis of Acute Diarrhea Diarrhea results when the net intestinal fecal loss of fluid and salt exceeds the absorbed amount.There are 5 pathogenic forms of diarrhea:Toxigenic diarrheaOsmotic diarrheaSecretory diarrheaInvasive diarrheaMotility disorders
27Toxigenic diarrheaToxins from bacteria, like enterotoxigenic E.coli or Vibrio cholerae, bind to specific receptors:labile toxin (LT) raises the level of cyclic guanosine monophosphate (cGMP) in the intestinal mucosa,stable toxin (ST) increases the adenasine 3׳:5׳-cyclic monophosphate (cAMP)This leads to blocking the absorption of Na and Clˉ ions into the villous enterocytes.LT induce the secretion of Clˉ and HCO3ˉ ions by crypt cells.
28Osmotic diarrhea Characterized by a positive osmotic gap of the stool Clinically, osmotic diarrhea is distinguished by the fact that the diarrhea diminishes when the patient fasts or stops eating the poorly ingested solute.
30Secretory diarrheaThere is no positive osmotic gap and the stool osmolality is equal to the ionic constituents: (Na + K)2 = stool osmolalityFood ingestion does not usually affect the stool volumeThe stool is watery without blood or pus and is characterized by very high volume and ion output
31Invasive diarrheaIs caused by direct mucosal damage by the invasive organismIt is similar to colitis and is usually associated with blood and mucous.
32Motility disordersHypermotility can cause diarrhea by reduction of contact time between intestinal mucosa and its contents, despite normal absorption function of the cellHypomotility can be primary, as in idiopathic intestinal pseudo-obstruction syndrome, or secondary to neuronal disorders.
33Clinical characteristics of infectious gastroenteritis in dependence on enteropathologic cause. OrganismCharacteristicsCommentsRotavirusIncubation period:2-3 d.Abrupt onsetFever (≥ 38°C) for 48 hhAssociated upper resp.tract infectionIncidence higher in cool weather6- to 24-month-old infants are more vulnerableNorwalk-like virusesInc.period:1-2 daysFeverLoss of appetiteNausea/vomitingAbdominal painMalaiseSource of infection: drinking water, foodAffects all agesSelf-limited
34Pathogenic Escherichia coli Incubation period: highly variableDiarrhea with moist-green, watery stool with mucus; becomes explosiveVomiting may be present from onsetAbdominal distensionFever, intoxicationIncidence higher in summerUsually interpersonal transmission, but may transmit via inanimate objectsSalmonella groups (nontyphoidae) – gram-negative, non-encapsulated, nonsporulatingIncubation period: 6 hh-21 dayRapid onsetVariable symptoms – mild to severeNausea, vomiting, and colicky abdominal pain followed by diarrhea, occasionally with blood and mucusInfants may be afebrile and nontoxicHighest incidence in children younger than 9 years, especially infantsTransmission – via contaminated food and drink, more commonly poultry and eggs
35Shigella groups – gram-negative, nonmotile, anaerobic bacilli Incubation period: 1-7 daysOnset usually abruptFever (to 40.5°C) and cramping abdominal pain initiallyFebrile convulsions in 10 % casesHeadache, neck rigidity, deliriumTransmitted directly or indirectly from infected personsVibrio cholerae groupsInc.period: 1-3 daysSudden onset of profuse, watery diarrhea without cramping, tenesmus, or anal irritationStools are intermittemt at first, then almost continuousStools are whitish, almost clear, with flecks of mucus – “rice water stools”Rare in infantsMortality is highTransmitted via contaminated food or water
36Food poisoning:StaphylococcusIncub.period:4-6 hoursNausea,vomitingSevere abdominal crampsProfuse diarrheaShock may occur in severe casesMay be a mild feverTransfered via contaminated food – inadequately cooked: custards, mayonnaise, cream-filled dessertsSelf-limited (24-72 hours)Exellent prognosisBotulismClostridium botulinum12 hr – 3 daysDiarrheaCNS symptoms with curare-like effectDry mouth, dysphagiaTransfered via contaminated foodVariable severity – mild symptoms to rapidly fatal within a few hoursAntitoxin administration
37Diagnosis Diagnosis is based on: the history, physical exam, and laboratory studies focused on evaluating the child's hydration status and identifying the causative agent.The history should include the following data:Recent exposure to infectious agentsTravel historyExposure to contaminated food and water suppliesExposure to turtlesAttendance at a day-care center
38If no systemic manifestations are present: Diagnostic laboratory tests are not indicated.Stool cultures should be performed for:children with a fever lasting more than 24 hours,blood or mucus in the stool,a family or household member with similar symptoms,or a positive stool white blood cell stain.
39Treatment The main treatment aims are: To prevent dehydration – restoration and maintenance of adequate hydration and electrolyte balance.Nutritional support, adequate to prevent protracted diarrhea and malnutrition.
40What about antimicrobial therapy? In about 30 % of patients no specific agent can be foundMost of the isolated pathogenic organisms are viralThe majority of the bacterial pathogens are self-limitedIn some cases, antimicrobial therapy prolongs the infection durationAntibiotic therapy has no effect on fluid transport nor on nutritional support
41When should antibiotics be used? In young infantsIn immunocompromised patientsWhen a systemic bacteremia is suspected.In case of specific persisting infection caused by Yersinia, Campylobacter, and Giardia
42RehydrationIn the majority of cases of acute diarrhea with mild or moderate dehydration, this aim can be achieved with oral rehydration solutions (ORS)1-3 tsp of ORS every 10-15min to start (even if vomits some)50ml/Kg/Hr is the goal for rehydration.Severe dehydration requires immediate admission to hospital and intravenous replacement of fluid and electrolytes.
43The rationale for the use of ORS During diarrhea, the normal mechanism for water and sodium absorption is impaired, so, the replacement of water or saline fluids alone will only lead to more diarrhea.The sodium-glucose-coupled transport generally remains intact. This mechanism stimulates water transport by solvent drag.
44The basic components of ORS GlucoseElectrolytesin an isotonic solution.In the World Health Organization formula the glucose concentration is 2 %.
45WHO recommendations for a sodium concentration 90 mEq/l, essentially for treatment of cholera30-60 mEq/l for countries, where cholera is not a concern and the stool sodium concentration in diarrheal illness is much lower30-40 mmol/l for neonates up to 2 mo whose kidneys have less capacity to excrete excess amounts of fluid and salt
46Rehydration FluidsThe World Health Organization recommends the following electrolyte concentrations for rehydration fluids:20 g glucose/L,90 mEq sodium/L,80 mEq chloride/L,20 mEq potassium/L,and 30 mEq bicarbonate/L.Encourage caregivers to look at product labels and make sure that the rehydration fluid they are choosing has the above electrolyte concentrations.
47Composition of oral electrolyte solutions (in mEq/l) Na+K+ClˉOther anionCHO(%)WHO solution902080302GastrolytePedialyte45352.5Rehydralyte7565infalyte5040
48Composition of “clear liquid” solutions Na+K+CHO(%)Pepsi Cola1-20.110.9Coca Cola10Root beer60.610.6
49Super-ORSRecent studies demonstrate the advantage of short glucose polymers as the carbohydrate source in ORSTraditionally it is widely used rice water % sugar syrup.Or carrot decoction: 500 g of cleansed carrot boil in 1 l of water during 1 hour, then mash it to homogenous mass and add boiled water up to 1 l. Boil for 10 min. Add 3 tsf of lemon juice. Give 1-2 teaspoon every 5-10 min up to 400 ml/day.
50Why are drinks high in glucose avoided during rehydration? Simple sugars increases the osmotic effect in the intestine by pulling water into the colon, thereby increasing diarrhea and subsequent fluid/electrolyte lossDrinks high in glucose: apple juice, sodas, jello water.Simple sugars increases the osmotic effect in the intestine by pulling water into the colon, thereby increasing diarrhea and subsequent fluid/electrolyte lossDrinks high in glucose: apple juice, sodas, jello water.
51Recommended foods during rehydration progression: In this question opinions differ: “bowel rest” versus “early feeding” is still controversial.Generally, formula feeding should be introduced gradually by starting with dilute mixtures.
52In practice, refeeding can start gradually after 24 hr of only fluid intake, i.e.,”bowel rest”. An exception is made for nursing infants, who should continue their regular feeding.Children already on solid foods are easier to handle. Food with a high content of disaccharides and monosaccharides (fruits, sweets) should be withheld in the convalescent period.Foods with starch carbohydrates (cereal, rice, noodles, bananas, potatoes, carrot, cooked fruits & vegetables), soups, yogurt should be encouraged.It is important to give often small food-intakes (up to 8-10 times per day)
53IV TherapyUsed for severe dehydration or in the child who will not/cannot tolerate ORSHalf 24hr maintenance plus replacement given within first 6-8hr (in ER) to rapidly expand the intravascular space. Usually a normal saline bolus.slower IV rate for the remainder of the first 24hrsnurse records IV vol infused hourly
54Rehydration and IV solution Why is the child initially rehydrated with a normal saline bolus and not an IV solution with potassium?Potassium is only added to an IV after the patient has voided to avoid hyperkalemia in a child with little or no urinary outputPotassium is only added to an IV after the patient has voided to avoid hyperkalemia in a child with little or no urinary output
55Adding Potassium to Intravenous Solutions Be sure that the child is able to void (1 -2 ml/kg/hr) before adding potassium to the IV.Children who are dehydrated are oliguric and can become anuric. An anuric child will not be able to excrete electrolytes that are in the IV solution; therefore, if potassium is added to the IV, it would result in an elevated serum potassium. An elevated serum potassium can cause cardiac irritability and ventricular fibrillation.Always check the dose and dosage calculations prior to giving. Never give more than 40 mEq/L at a rate not to exceed 1 mEq/kg/hr.After adding potassium to an IV bag, shake it to make sure the potassium is equally distributed.Never give potassium by IV push.
56Which of the following IV solutions replaces Sodium? D5 WLactated RingersNormal SalineD5 ½ NSAnswer: All but D5 W
57Calculation of intravenous fluid needs: maintenance For the 1st 10 Kg, replace at 100ml/Kgfor the second 10 Kg, replace at 50ml/Kgfor >20kg, replace at 20ml/Kg
58Example of Maintenance Fluid Calculation Your patient is a 10 yr old weighing 35 Kg. You want to determine this patient’s 24hr maintenance fluid needs:for the first 10 Kg give 100ml/Kg = 1000mlfor the second 10 Kg: ml/Kg = 500mlfor the remaining 15 Kg (35-20Kg) , replace at 20 ml/Kg: 15 = 300ml= 1800 ml/day.
59How much fluid should this patient get per hour? 1800 ml / 24 hrs = 75 ml/hr.Therefore, if the patient was NPO and not taking in fluids from any other source, the IV should be running at 75ml/hr.If there is a deficit that also needs to be replaced, the IV rate may be slightly higher for a defined period of time.If the patient is receiving fluids from other sources, these need to be accounted as well
60Practice Problems for Calculating 24hr Fluid Maintenance and the hourly IV rate for: A 9 yr old patient who weighs 20 Kg.A 6 mo old baby who weighs 8 KgAn 24mo old toddler who weighs 18 KgA 3 yr old preschooler who weighs 28 KgAn 18 yr old who weighs 50 Kg9yr old wt 20 Kg = 1500ml/day6 mo old wt 8Kg= 800ml/day36mo old wt. 18 Kg= 1400ml/day3yr old wt 28Kg=1660ml/day18yr old wt 50Kg= 2100ml/dayAdult > 50Kg= 2-3L/day
61Answers for 24hr Fluid Calc. 9yr old wt 20 Kg = 1500 ml/day6mo old wt 8Kg= 800 ml/day36mo old wt 18 Kg= 1400 ml/day3yr old wt 28Kg=1660 ml/day18yr old wt 50Kg= 2100 ml/dayAdult > 50Kg= 2-3 L/day
63Clinical Assessment / Management of Edema assess dependent limbs if ambu or sacrum if lyingascites; periorbital edema; rings too tightpitting edema for degree of swellingdaily wt and strictly In and Outelevation/change position Q2hr/ protect skin against breakdowndistraction to deal with discomfort and limitations of edema.
64Electrolyte Imbalances Electrolytes usually gained and lost in relatively equal amounts to maintain balanceImbalance caused by:Abnormal route of loss (vomiting/diarrhea) can disturb electrolyte balanceDisproportionate IV supplementationDisease states: renal dis.
65Hypernatremia Excess serum sodium in relation to water Causes: Too concentrated infant formulaNot enough water intakeClinical manif.: thirst, lethargy, confusionSeizures occur when rapid or is severe.SG concentratedLab test: serum sodiumTreatment: hypotonic IV solution
66Hyponatremia Excess water in relation to serum sodium Most common sodium imbalance in childrenCauses:Infants vulnerable to water intoxication:dilute form, excess pool water, poorly developed thirst mech so cont to drink and can’t excrete excess water.
67Hyponatremia (cont)Clinical manif: decreased level of consciousness d/t swelling of brain cells.Anorexia, headache, muscle weakness, decreased DTR’s, lethargy, confusion or coma.Seizures occur when rapid or severe.SG dilute:Lab tests: serum sodiumTreatment: hypertonic solution.
68Hyperkalemia Excess serum potassium Causes: excess K intake from IV overload, blood transfusion, rapid cell death (hemolytic crisis, large tumor destruction from chemo rx, massive trauma, metabolic acidosis from prolonged diarrhea and in DM when insulin levels are lowInsulin drives K back into the cellsdecreased K loss from Renal insufficiency
69Hyperkalemia (cont)Clinical manif: all are related to muscle dysfunction: hyperactivitiy of GI smooth muscle: intestinal cramping and diarrhea.Weak skeletal musclesLethargyCardiac arrhythmias (tachycardia, prolonged QRS, peaked T waves: also AV block and VTach).Lab test: serum potassiumTreatment: correct underlying condition (take K out of the IV)dialysis (peritoneal or hemo), Kayexalate (po or enema), K wasting diuretics, IV calcium, bicarbonate, insulin and glucose.Low potassium diet.
70Hypokalemia Decreased serum potassium Causes: diarrhea and vomiting, ingestion of large amts black licorice, diuretics, osmotic diuresis (glucose in urine as in DM), NPO without K replacement in IV, NG Sx, bulimia, insulin.Also in nephrotic syndrome, cirrhosis, Cushing Syndrome, CHF (to be covered elsewhere)
71Hypokalemia (cont) Clinical manif: muscle dysfunction Slowed GI smooth muscle resulting in abdominal distention, constipation and paralytic ileusSkeletal muscles are weak; may effect respiratory musclesCardiac arrhythmias: hypokalemia potentiates Digitoxin Toxicity.Lab test: serum potassiumTreatment: oral and/or IV potassium, diet rich in K.
72Hypercalcemia Excess calcium Needs vit D for efficient absorption; most of Ca is stored in the bones.Causes: bone tumors that cause bone destruction, chemo rx release Ca from the bones; immobilization causes loss from the bones (usually excreted) but if kidneys can’t clear it, hypercalcemia results, increased intake (milk-alkali syndrome).
73Hypercalcemia (cont)Clinical manif: Ca imbalances alter neuromuscular irritability with non-specific symptomsConstipation, anorexia, N/V, fatigue, skeletal muscle weakness, confusion, lethargy.Renal calculi, cardiac arrhythmiasHyperCa increases Na and K excretion leading to polyuria and polydipsia.Rx: serum Ca, Ionized Ca, fluids, Lasix, steroids, dialysis.
74Hypocalcemia Decreased serum calcium Causes: decreased intake of Ca and/or Vit D (adolescents are vulnerable d/t fad diets and the deficit cannot be made up later, increasing risk for osteoporosis).Limited exposure to sunlight, premature infants and dark skinned people at increased risk to inadeq. Vit D and therefore decreased Ca absorption.Parathyroid dysfunction, multiple transfusion (Citrate binds Calcium), steatorrhea (as in pancreatitis and Cystic Fibrosis) binds Calcium in the stool.
75Hypocalcemia (cont)Chvostek’s Sx: tap the skin lightly in front of the ear (over the facial nerve), if the corner of the mouth draws up, d/t muscular contraction = +Chvostek’s Sx.Trousseau’s Sx: + if carpal spasm after BP cuff inflated ~ 3min.Clinical Manif:acute situation related to increased muscular excitability: tetany. +Chvostek’s Sx, + Trousseau’s Sx.In children: Twitching, cramping, tingling around the mouth or fingers, carpal/pedal spasms.In infants: tremors, muscle twitches, brief tonic-clonic seizures, CHF.Laryngospasm, seizures and cardiac arrhythmias in severe situations.Chvostek’s Sx: p 755 tap the skin lightly in front of the ear (over the facial nerve), if the corner of the mouth draws up, d/t muscular contraction, + Chvostek’s Sx.Trousseau’s Sx: + if carpal spasm after BP cuff inflated ~ 3min.
76Hypocalcemia (cont 2)In children and adolescents, chronic hypocalcemia more common, manif. By spontaneous fractures. Lab tests: serum Ca; bone density study Rx: oral and/or IV Ca, Ca rich diet
77Hypermagnesemia Excess in Mg. Imbalances characterized by neuromuscular irritabilityCauses: impaired renal function, Mag Sulfate given perinatally to treat eclampsia, increased use of laxatives, enemas, antacids, IV fluid additives.
79Hypomagnesemia Decreased serum Mg. Stored in cells and bones Causes: prolonged NPO without replacement, chronic malnutrition, chronic diarrhea, short bowel syndrome, malabsorption syndromes, steatorrhea, multiple transfusions, prolonged NG Sx, some medications.
80Hypomagnesemia (cont) Clinical manif: increased neuromuscular excitability (tetany). Hyperactive reflexes, skeletal muscle cramps, twitching, tremors, cardiac arrhythmias, seizures.Lab: serum Mg along with Ca and K.Rx: po/IV Magnesium admin and treating underlying cause of imbalance.
81Critical Thinking: Clinical Evaluation of Fluid and Electrolyte Imbalance How can you evaluate children appropriately for fluid and electrolyte imbalance without thinking through the clinical manifestations of every possible disorder, one after the other?3 paragraphs of text that review this concept and pull the content together with clinical application:1) risk factor assessment2) exam several body systems: cardiovascular, respiratory, neurological3) look for factors that alter intake, retention, and loss of fluids and electrolytes4) consider growth and development to realize problems most common to the age group.5) clinical assessment: wt, fluid balance, vascular volume (BP, HR), interstitial volume (edema?), mentation, DTR’s, muscle irritability, GI function, cardiac rhythm, assess electrolyte levels.
82Answer to Critical Thinking: 3 paragraphs of text that review this concept and pull the content together with clinical application:1) risk factor assessment2) exam several body systems: cardiovascular, respiratory, neurological3) look for factors that alter intake, retention, and loss of fluids and electrolytes4) consider growth and development to realize problems most common to the age group.5) clinical assessment: wt, fluid balance, vascular volume (BP, HR), interstitial volume (edema?), mentation, DTR’s, muscle irritability, GI function, cardiac rhythm, assess electrolyte levels.
83Fluid and Electrolyte Worksheet Use the fluid and electrolyte worksheet to help review some of the major concepts of fluid and electrolyte imbalance.
84pH - Is the acidity or alkalinity of a solution. - From French pouvoir hydrogène ("hydrogen power“)- pH is the Hydrogen ion concentration [H+] of asolution.- It is a measure of the solution's acidity.pH is defined as the negative logarithm of the concentration of H+ ions:pH = -log10[H+]
85The greater the concentration of H+, the more acidic a solution is. The lower the concentration of H+, the more basic or alkaline a solution becomes.Neutral1714AcidicAlkaline
87Acid Base Balance normal arterial blood pH: 7.35-7.43 (in general) Acidosis < 7.35 : too much acidAlkalotic > 7.43 : too little acidpCO2 reflects carbonic acid status:40 mmHg (+- 5)HCO3- reflects metabolic acid status:24 mmol/l (+- 4)
88Respiratory Acidosis caused by decr respir effort build up of CO2 in the bloodpH decr or normal; pCO2 incr.Symptoms manifested: confusion, lethargy, HA, incr ICP, coma, tachycardia, arrhythmias
89Management of Respiratory Acidosis Incr ventilatory rategive O2intubateadm NaHCO3
90Clinical Conditions that cause Respir Acidosis conditions associated with decreased respiratory drive, impaired gas exchange/air trapping, ie:head trauma, general anesthesia, drug overdose, brain tumor, sleep apnea, mechanical under ventilation, asthma, croup/epiglottitis, CF, atelectasis, MD, pneumothorax.
91Respiratory Alkalosis caused by hyperventilationCO2 is being blown offpH incr : pCo2 decrSymptoms: dizziness, confusion, neuromuscular irritability, paresthesias in extremities and circumoral, muscle cramping, carpal or pedal spasms.
92Management of Resp. Alkalosis First determine if oxygenation is adequate, if not, you don’t want to slow the RR.Determine the cause and correct it:Causes of hypervent: hypoxemia, anxiety, pain, fever, ASA toxicity, meningitis/encephalitis, Gram - sepsis, mechanical overventilation.Ipecac is no longer recommended for treatment of ingestions.
93Metabolic Acidosis caused by a loss of bicarbonate (HCO3) therefore, is an incr of acids in the bloodpH decr or moving towards normalpCo2 decr ; HCO3 decrSymptoms: Kussmaul respirations = incr rate and depth as compensation (hyperventilation / acetone breath), confusion, hypotension, tissue hypoxia, cardiac arrhythmias, pulmonary edema.
94Management of Metabolic Acidosis Identify and treat underlying causeIn severe case may give IV NaHCO3 to incr pH, or insulin/glucose.Causes of MA for gain of acid: ingestion of ASA, antifreeze, oliguria, RF, HAL, DKA, starvation or ETOH KA, lactic acidosis (tissue hypoxia).Loss of HCO3: maple syrup urine disease, diarrhea, RF.
95Metabolic Alkalosis caused by loss of H+ or HCO3 retention HCO3 incr with probable incr in pH, incr pCO2.Symptoms:weak, dizzy, muscle cramps, twitching, tremors, slow shallow resp., disorientation, seizures.
96Management of Metabolic Alkalosis correct underlying cause; facilitate renal excretion of HCO3.admin NS, K+ if hypokalemic, replace loss of fluids, prec for Sz, monitor I and O and electrolytesCauses: prolonged vomiting, ingestion of lg quantities of bicarb, antacids, loss of NG fluids, hypokalemia from prolonged diuretic use, multiple blood transfusion with citrate.
97ABG Basic (Uncompensated) Analysis Resp Acidosis: low pH and high PaCO2Resp Alkalosis: incr pH and low PaCO2Metab Acidosis: low pH and nl PaCo2; decr HCO3Metab Alkalosis: high pH; nl PaCO2 ; high HCO3
98ABG Analysis with Compensation Resp Acidosis: HCO3 will incr, pH will approach nl; PaCO2 will still be increasedResp Alkalosis: HCO3 will decr, pH will approach nl; PaCO2 will still be decreasedMetab Acidosis: PaCO2 will decr, pH will approach nl; HCO3 will still be decreasedMetab Alkalosis: PaCO2 will incr, pH will approach nl; HCO3 will still be increased