Chapter
133
Fluid Therapy in Medical Disorders
Sanjay Pandya
Almosteverythirdhospitalized thirdhospitalizedpatientneeds patientneedsuidinfusion. uidinfusion.Dierent Dierent typesofuidsareusedforintravenous(IV)therapy. typesofuidsareusedforintraven ous(IV)therapy.Inappropri Inappropriate ate IVuidtherapy(inco IVuidthera py(incorre rrectvolum ctvolume e orincor orincorrec rect t typ type e ofuid)is a signicantcauseofpatientmorbidityandmortality.1Administration ofthewrongtypeofuidresultsinderangementofserumsodium concentration,which,ifsevere,leadstoseriousneurologicalinjury. SoitisimportanttohaveabasicunderstandingofthedierentIV uidsandtochoosetheuid uidsandto choosetheuidmostappropriatetothepati mostappropriatetothepatient’s ent’sneeds. needs. Properuidmanag Pro peruidmanageme ementplaysvery ntplaysvery vit vitalrole alrole intreat intreatmen ment t ofall criticalpatients.
Step 4: Determine Rate of Fluid Administration
Planning and Preparing Prescription of Intravenous Fluids
Intravenousuidstobeinfusedinagivenpatientisselectedonthe basisof • Com Composi positio tiono nofI fIV Vuid uids( s(Tables 4 to 7). • Unde Underly rlying ingetiol etiology ogy andpre andpresenc senceofelect eofelectrol rolyte ytesandacidsandacid-base base disorders. • Selecti Selectionof onofintra intravenous venousuids uids(Conside (Consideringi ringitsCom tsCompositi position). on).
• Howfast Howfast to gi give ve IV u uid idsaredec saredecid idedonthe edonthe ba basi sisof sof cl clin inic ical al asses ass essm smen ent. t. Ac Acut ute e lo losse sses s sh shou ould ld be re repla place ced d qu quic ickly kly, , wh whil ile e chroniclossesshouldbereplacedwithcaution.
How Much Fluid to Give?
Properassessmentofvolumestatus(Table 1)andinsickpatients’ invasivemethods(Table 2)helpstodeterminethevolumeofuid to be infused. Add the patien patient’ t’s s daily maint maintenance enance requi requiremen rements ts tothe ui uid d need needed ed toreplac toreplace e the los lossesto sesto mak make e the tot total al dail daily y requirement.WatchcarefullyforaresponsetoIVuidsandmodify WHY PATIENTS NEED INTRAVENOUS FLUID THERAPY? Patien Pat ient t need needs s IV ui uid d the therap rapy y for mai mainte ntenanc nance e (to sup supply ply dai daily ly volumeand rateof uidinfusion, ifnecessar y.Since uidoverload needs),replac need s),replaceme ement(to nt(to rep replac lace e de decit cit andon-goi andon-goinglosses) nglosses) and iscommon,monitoreverypatientcloselyandbealertforitssigns (Table 3). resuscitation(tocorrectanintravascularorextracellulardecit). Eve very ry pa pati tien ent t res espo pond nds s di die erren entl tly y to u uid id th theera rapy py. . Mo Morre importantthananyruleonthevolumeofreplacementuidsisto Aims of Fluid Therapy observethepatient’sresponsetovolumeinfusion. observethepatient’ sresponsetovolumeinfusion.esignsthatyou esignsthatyou • Correc Correctiono tionofshoc fshockande kandestabli stablishpro shproperti pertissuepe ssueperfusio rfusion n havegivenadequateIVuidsandcanslowtheinfusionareincrease • Correc Correctuid tuiddeci decitand tandongoin ongoinglosse glossess inhypotension,reductionintachycardia,increaseinjugularvenous • Toprovidemaintenancerequir providemaintenancerequirementof ementofuidelectrolyte uidelectrolyteifneeded ifneeded pressureandincreaseinvolumeofurineinoliguricpatient. • Prope Properselec rselectiono tionofuid fuidsoasto soastocorr correctel ectelectro ectrolytea lyteandacid ndacidbase base disordersimultaneously. Which Fluid to Give?
Goalofuidtherapyistoprovidetherightamountoftherightuidat therighttime.Basicprincipleofuidtherapyisthatuidreplacement shouldbeascloseaspossibleinvolumeandcompositiontothose uidslostforgivenpatient.
Step 1: Assessment
Presentation TABLE 1 │ Presentation
Whileplanninguidtherapyitisessentialtoconsider: • Vo Volume lumestatu statusofpa sofpatient tient(sever (severityo ityofdehy fdehydratio dration) n) • Eti Etiolog ologyo yofd fdehy ehydra dratio tion n • Prese Presenceof nceofelect electrolyt rolytediso edisorders rders(Naa (NaandK) ndK) • Prese Presenceof nceofacid acidbasedi basedisorder sorderss • As Asso soci ciat ated ed co coex exiist stin ing g di diso sorrde ders rs [i [i.e .e. . di diab abet etes es me mell lliitu tus, s, hypertension, hypert ension,congestive congestiveheartfailure(CHF),renalfailur heartfailure(CHF),renalfailure,liver e,liver failure,etc.].
A.
Step 2: Calculation of Volume of Intravenous Fluids
C.
• Onthebasiso Onthebasisofvolum fvolumestat estatusamo usamountof untofIVui IVuidstob dstobeinfus einfusedis edis calculated.
Step 3: Selection of Intravenous Fluids • Accordingtothe Accordingtothenatureofuid natureofuiddecitand decitandpresenceof presenceofelectrolytes electrolytes andacidbasedisordersselectappropriateIVuids.
of dehydration
Mild dehydration: Up to 5% total body water (3 L in 70 kg man) Normal mental state, dry mucous membranes, usually thirsty, blood pressure and heart rate normal, lower than normal urine output and skin turgor almost normal
B.
Moderate Moder ate dehydrat dehydration: ion: 5–10% 5–10% total total body water (5 L in in 70 kg man) man) Disinterest in surroundings, can be drowsy, increased heart rate and respiratory rate, orthostatic hypotension, decreased skin turgor and reduced urine output Severe Seve re dehydratio dehydration: n: 10–15% 10–15% total total body water (8 L in in 70 kg man) Reduced conscious level, fast heart rate, low blood pressure, respiratory distress and oliguria/anuria
TABLE 2 │Invasive methods for
assessment of body uids
Central venous line, arterial line and pulmonary artery catheter
Nephrology
Section 17
• ForproperselectionofIVuiditisessentialtorememberbasic factsaboutitscontents. ConsideringabovementionedbasicfactsproperselectionofIV uidshouldbedoneforgivenpatient.
Selection of Intravenous Fluid in Common Clinical Problems Fluid therapy in hypovolemic shock: Fluid loss leading to
hypo volemia, hypotension and shock can be life threatening and requires emergent medical intervention. Amount of uid to be given is decided by clinical and other guidelines (Table 1).Mostimportantquestionto beansweredis that which uidshouldbegivenandwhy? Potency of various IV uids, colloids and blood products are dierent in correcting hypotension and shock, depending on its abilitytoexpandintravascularvolume(Table 8). Selection of intravenous solution for initial treatment of hypovolemic shock: • Fluids to be avoided :5%dextrose,allisolyteuids. • Most eective agents :Colloids,albumin,bloodproducts. • Most preerred fuids :Isotonicsaline,Ringer’slactate. For initial treatment of hypovolemic shock: Avoid5% dextrose: Avoid 5% dextrose because (a) it is ineective in raising blood pressure(1,000mlofD-5%willincreaseintravascularvolumeonly by83 ml); (b)Itcarriesriskof hyponatremia (asitlackssodium) and(c) It leadsto urinary uidloss.Largerand fasterinfusion of D-5%(>25g/hour)willleadtohyperglycemiaandosmoticdiuresis. Two distinct disadvantages of osmotic diuresis are (1) it delays
TABLE 3 │Signs and symptoms
correctionofdehydrationand(2)itmisguidesclinicianbycreating falseimpressionthatthereissatisfactorycorrectionofuiddecit. Insuch setting rateof uidreplacementmay bereduced,despite hypovolemia.iscanbedetrimental. Avoidallisolytes: Isolyte-M, -P and -G,allshouldbeavoided ininitialtreatmentofhypovolemicshockbecauseofpoorsodium content(solesseectiveincorrectinghypotension);highpotassium content(risk of hyperkalemia in oliguricpatient)and itsdextrose content(canleadtoosmoticdiuresisanduidloss). Isotonicsalineismostpreferred:Becauseitcorrectshypotension eectively(1,000mlofsalinewillincreaseintravascularvolumeby 300mlsoeectiveinraisingbloodpressure)andissafeevenwhen glycemicstatusis notknown.2 Advantagesof salineovercolloids/ bloodproductsarelesscost,easyavailabilityandnoriskofreaction. Ringer’s lactate (RL) is preferred uid: Because RL corrects hypotensioneectively(1,000 ml ofRL willincreaseintravascular volumeby200to240 mlapproximately,soeectivein raisingblood pressure)anditismostphysiologicalcompositionofRLissimilar toextracellularuid,solargevolumeofRLcanbeinfusedwithout fearofelectrolyteimbalance.Ifpatientneedsmorethan3–4liters ofnormalsaline,itcarriesriskof“expansionacidosis”andtherefore balancedsalt solution—Ringer’slactateshouldreplace0.9% saline (except in cases of hypochloremia, e.g. from vomiting or gastric drainage). Colloids,albumin,bloodproductsmosteectiveagents:Allthese agentsaredistributedchieyinintravascularcompartment,sothey correct hypotensionmost eectivelywith leastvolume.3 However considering its cost and possible side eects, it should be used judiciously.4,5
Fluid Therapy in Diarrhea
of uid volume excess
As diarrheal uid is rich in sodium, bicarbonate and potassium, diarrhealeadstohypokalemichyperchloremicmetabolicacidosis with dehydration. Most of the patients with diarrhea-induced
Tachycardia, increased blood pressure, edema, weight gain, orthopnea, distended neck veins, gallop rhythm, pulmonary edema, ascites and pleural effusion.
TABLE 4 │ Sodium concentration of
Intravenous uids
Isotonic saline
various intravenous uids Ringer’s Isolyte-G 0.45% lactate saline
Na (mq/L)
154
130.0
77
63
Isolyte-M
Isolyte-P
40
25
3% NaCl 2 ml = 1 mEq Na, 7.5% NaHCO3 10 ml = 9 mEq Na
TABLE 5 │ Potassium concentration of
Intravenous uids Isolyte-M
intravenous uids Isolyte-P Isolyte-G
K (mEq/L)
20.0
TABLE 6 │ Characteristics of
Characteristic
intravenous uids Intravenous uids
17.0
KCl (15%) Amp
4.0
20 mEq/10 ml
Characteristic
Intravenous uids
Most physiological
RL
Glucose free
Saline, RL
Rich in sodium
NS, DNS, RL
Sodium free
Dextrose solutions
Rich in chloride
NS, DNS, Iso-G
Potassium free
NS/DNS, dextrose solution
Rich in potassium
Iso-M, P and G
Avoid in liver failure
RL, Iso-G, 5% D
Corrects acidosis
RL, all isolyte Except Iso-G
Corrects alkalosis
Isolyte-G, NS
Abbreviations:
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35.0
Ringer’s lactate
Avoid in renal failure Provides phosphorous
RL, Ringer’s lactate; NS, Normal saline; DNS, Dextrose normal saline; Iso-G, Isolyte-G; Iso-M, Isolyte-M.
NS, RL, all isolyte Isolyte-M
Chapter 133
Section 17 TABLE 7 │Initial selection of
Clinical disorder
Fluid Therapy in Medical Disorders
intravenous uids for various clinical disorders Ideal initial uid Clinical disorder
Ideal initial uid
Hypovolemic shock
NS, RL
Burns
Ringer’s lactate
Diarrhea
Ringer’s lactate
Intraoperative
Ringer’s lactate
Vomiting
Isotonic saline
Starvation defcit
5% dextrose
Diabetic ketoacidosis
Isotonic saline
Hypokalemia
Isolyte-M, KCl drip
Adult maintenance
Isolyte-M
SIADH
3% NaCl + IV frusemide
Post TURP
NS, Avoid 5% D
Stroke, neuro surg
NS, Avoid dextrose sol.
Abbreviations:
RL, Ringer’s lactate; Iso-G, Isolyte-G; Iso-M, Isolyte-M; Iso-P, Isolyte-P; Injection KCl, Injection Potassium chloride; NS, Normal saline; DNS, Dextrose normal saline, 3% NaCl Hypertonic saline, Injection NaHCO3, Injection sodium bicarbonate; TURP, Transurethral resection of the prostate; SIADH, Syndrome of inappropriate antidiuretic hormone secretion; IV, Intravenous
TABLE 8 │Rise in intravascular
Type of uid (1,000)
5% Dextrose
Rise in intravascular volume
83 ml
volume with intravenous agents Isotonic saline Colloids/Blood 300 ml
Roughly 100%
dehydrationcanbetreatedeectivelywithORS. 6Fewpatientswith severedehydrationandshockneedIVuidtherapy.Ringer’slactate is mostpreferredIV uidto correct dehydration.Lactate content ofRLgetsconvertedintobicarbonatebyliver.AsRLadditionally provides bicarbonate it is preferred uid in diarrhea. In severe formofdiarrheawithacidosisandhypokalemia,treatmentofboth disorders needs to be done simultaneously and meticulously. If onlymetabolicacidosisiscorrectedrapid,potassiumwillbeshifted intracellularly.Ifpatientishypokalemic,onlycorrectionofacidosis canprecipitatedangeroushypokalemia.Commoncomplaininsuch situation is weakness,uneasinessand diculty inbreathingwith fallinSPO2. On the contrary, without correction of acidosis, potassium supplementationcancausedangeroushyperkalemia.isisdueto failureofpotassiumshiftintotheintracellularcompartment(dueto acidosis),eveninstateofpotassiumdecitofthebody.
Fluid Therapy in Vomiting Vomitingleads to hypokalemic hypochloremicmetabolic alkalosis with dehydration. Most preferred IV uid to correct dehydration due tovomiting isisotonicsaline. Salineprevents further loss of potassiumandeectivelycorrectsrestofallelectrolytesandacidbaseddisordersdueto vomiting.Torestore previousand ongoing potassiumlosses,30–40 mEq/lpotassiumis addedto saline(after correctionofshockandinabsenceofoliguriaorrenalfailure). Isolyte-Gisthespecicuidusedforthereplacementofupper GIloss, asit correctsall electrolyteabnormalities.is isthe only uidwhichcorrectsmetabolicalkalosisdirectly.Howeverthisuid shouldnotbeused: • Inpresence ofshock,oliguriaandrenal failure (because of17 mEq/lpotassium) • In patients w ith liver disorder ( becaus e of its content ammoniumchloride,whichcanprecipitateoraggravatehepatic encephalopathy)and • Inpresenceof associateddiarrhealeadingto acidosis(because Isolyte-G by providing H ion aggravates acidosis caused by diarrhea).
Fluid Therapy in Combined Loss: Diarrhea and Vomiting MostpreferredIVuidtocorrectcombinedlossduetodiarrheaand vomitingisisotonicsalinewithpotassiumsupplementation.Ringer’s lactatepreferredtocorrectdecitduetodiarrhea,isdetrimentalin vomiting, as it aggravates metabolic alkalosis. Similarly Isolyte-G preferredtocorrectdecitduetovomiting,isdetrimentalindiarrhea asitaggravatesmetabolicacidosis.
Fluid Therapy in Hyponatremia Hyponatremiaisthemostcommonandfrequentlymissedelectrolyte disorder.Inallpatientsreceivingmaintenanceuids,measureserum sodium concentration dailyto prevent hyponatremia. Completely avoidallhypotonicuidsinpatientswhoseserumsodiumconcentration is low or falling rapidly (by > 8 mmol/L per day). Acute decreasesinserumsodiumconcentrationbelow125 mmol/Lwith neurologicalsymptomsisamedicalemergency,andneedsprompt, controlledcorrection of serumsodiumconcentration.Remember, rapidcorrectionofchronicorasymptomatichyponatremiacanbe detrimental.7 • Ruledoutpseudohyponatremia • Hyponatremiawithdehydration(combinedlossofbothsaltand water,i.e.cholera):Supplementbothuidandwater,i.e.isotonic salineorRinger’slactate • Hyponatremia with hypervolemia/anasarca (retention ofboth, but retention of water greater than retention of salt, i.e. CHF, cirrhosisofliver):Restrictbothuidandwaterwithloopdiuretics • Hyponatremia with euvolemia (retention of water and loss of salt, i.e. Syndrome of inappropriate antidiuretic hormone secretion):3%NaCl-hypertonicsalineinsymptomaticpatients, with strict uid restrictiona nd loop diuretics.Newer treatment modalityineuvolemicandhypervolemichyponatremiaisvaptan (Vasopressin receptor antagonists). Advantages of vaptans are that they excrete only free water, without loss of sodiumand potassiumandraiseserumsodiumconcentration.
Fluid Therapy in Hepatic Encephalopathy Basic Principles of Fluid Selection • Avoidhypoglycemia(high-riskdueto hepaticfailureleadingto decreasedglycogenstorage). • Avoid hypokalemia and metabolic alkalosis (high-risk due to vomitingand diuretics).ese abnormalitiesmay precipitateor aggravatehepaticencephalopathy.
607
Nephrology • Avoid hyponatremia (high-risk due tovomiting andimproper sodiumdecituidinfusion).eseabnormalitiesmayaggravate cerebraledema. • Avoid hypotonic uid (like 5% dextrose, which can aggravate cerebraledema).
lowosmolality(Plasma285mOsm/LversusRL274mOsm/L)and presence of calcium in same,which maypromotereperfusion injury. • IsotonicsalineistheidealIVuid.
Selection of Fluids
• Select appropriate uids considering etiology and associated electrolytes/acidbasedisorders • Incorrection ofhypovolemic shockisotonicsalineis the most preferred–uid and colloid or bloodproductsare mostpotent agents. • In diarrhea RL, in vomiting isotonic saline and in combined loss isotonic salinewith potassium supplementation are most preferredIVuids. • Inhyponatremia,principlesofuidandsaltsupplementationare totallydierenthydrationstatus. • Inhepaticencephalopathygoalofuidtherapyistopreventand correctdehydration,hypoglycemia,hypokalemia,hyponatremia andmetabolicalkalosisandtoavoidhypotonicuids.
• 20%dextroseispreferredasitprovidesgreatercaloriesinlesser uidvolume. • Provide adequate sodium rich uids to correct decit due to vomitinganddiureticsand toprovidemaintenanceneed (about 100mEqsodiumperday).Similarlyprovideadequatepotassium supplementationto correctdecitand toprovidemaintenance need. • AvoidRinger’slactate.Duetohepaticdysfunctionlactatemaynot getconvertedintobicarbonatebyliveranditsaccumulationmay leadtolacticacidosis. • AvoidIsolyte-G.Duetohepaticdysfunctionammoniamaynot getconvertedintoHionandureabyliveranditsaccumulation mayleadtohepaticencephalopathy. • Edematouscirrhoticpatientsneeduidandsaltrestriction.
Fluid Therapy in Initial Phase of Stroke Basic Principles of Fluid Selection Ininitialtreatmentofpatientswithstroke:8 • Maintaineuvolemia.Avoidhypovolemiaandhypotension. • Avoidhypotonicuidandhypo-osmolality(whichcanaggravate cerebraledema). • Avoid hyperglycemia (which can enhance brain injury and breakdownofBBB).
Selection of Fluid • Avoid5%dextrose,asitishypotonicanditleadstohyperglycemia • Ringer’slactateisappropriateuidifvolumeofinfusionissmall. Butavoidiflargeuidvolumeisrequiredbecauseofitsslightly
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Section 17
SUMMARY
REFERENCES 1. PandyaS.Practicalguidelinesonuidtherapy,2ndedition;2005. 2. ChoiPT, YipG,Quinonez LG,et al. Crystalloids vs.colloidsin uid resuscitation:asystematicreview.CritCareMed.1999;27(1):200-10. 3. MartinGS,LewisCA.Fluidmanagementinshock.SeminRespirCrit CareMed.2004;25(6):683-93. 4. AmericanoracicSociety.Evidence-basedcolloiduseinthecritically ill:AmericanoracicSocietyConsensusStatement.AmJRespirCrit CareMed.2004;170(11):1247-59. 5. SchierhoutG,RobertsI.Fluidresuscitationwithcolloidorcrystalloid solutions incriticallyill patients:a systematicreviewof randomized trials.BMJ.1998;316(7136):961-4. 6. Rehydration project. ‘Why isRehydration soImportant and How it WorkstoSaveChildren’sLives’.[online]Availablefromwww.rehydrate. org/rehydration.[AccessedJune,2009]. 7. VaidyaC,HoW, Freda BJ.Managementofhyponatremia:providing treatmentandavoidingharm.CleveClinJMed.2010;77(10):715-26. 8. HackeW,KasteM,SkyhojOlsenT,etal.Acutetreatmentofischemic stroke.CerebrovascDis.2000;10(Suppl3):22-33.