Fundamentals exam 2
Fluid and electrolytes
Fluid Facts
• Water- primary body fluid and most critical element; the fundamental solvent for all
biochemical processes in the body
• Total body water or fluid comprises about 50-40% avg. adult weight
• Loss of 5-10% body fluid=SERIOUS
• Loss of 15-20% body fluid=may be FATAL
• Fluid gained each day should=fluid lost each day (2-3L/day average)
Fluid Compartments
• Intracellular Fluid:
o =Fluid within cells
o -2/3 (70%) of total body water
• Extracellular Fluid (ECF)=Fluid outside of cells
o -1/3 (30%) of total body water
o 3 divisions:
▪ Interstitial (fluid that surrounds tissue cells including lymph)
▪ Intravascular/plasma (liquid part of the blood)
▪ Transcellular (minor compartment)
Variations in Fluid Content
• Fat has a tiny amount of water; lean tissue (muscle) has lots of water
• Females have less body fluid than males
• Age variations exist rin rregards rto rwater rcontent rof rfluid rcompartments
o Older radults r(after rthe rage rof r60) rhave rless rpercentage r(45%) rof rbody rfluid
o Infants rhave rmore rtotal rbody rfluid rand rECF rthan radults=605 rof rH2O ris
rfounf rin rECF, r40% rof rH2O ris rfound rin rICF
• What rmight rthis rmean rin rregards rto rfluid rloss rfor ran rinfant?
• What rage rgroups rat rhigher rrisk rfor ralterations rin rbalance?
Fluid rBalance rExample
• How rto rcalculate rnet rfluid rintake rand rnet rfluid routput?
o A rclient rdrinks r1000 rmL r(I) rof rwater, reats rfood rcontaining r500 rmL rof rwater r(I), rand
the rclient rvomits r250 rml r(O) remesis rover r24 rhours. rThe r24-hour rnet rgastric
rfluid rintake ris: r1000(I) r+ r500(I) r-250(O)=1250 rmL
o Another rclient rhas ra rNG rtube rin rplace. rThe rNG rirrigation rfluid ris r200 rmL r(I),
rthe rNG rdrainage routput ris r1300 rmL(O), rand rthe remesis ris r300 rmL r(O) rover
r24 rhours. rThe r24-hour rnet rgastric rfluid routput ris r1300(O) r+ r300(O) r-200(I)=
r1400 rmL
,Electrolytes
• Works rwith rfluid rto rkeep rthe rbody rhealthy rand rin rbalance
• They rare rsolutes rthat rare rfound rin rvarious rconcentrations rand rmeasures rin
rterms rof rmilliequivalents r(mEq) runit
• Can rbe rnegatively rcharged r(anions) ror rpositively rcharged r(cations)
• For rhomeostasis rbody rneeds: rTotal rbody ranions r(e.g. rchloride, rbicarbonate, rphosphate)
=Total rbody rcations r(e.g. rsodium, rpotassium, rcalcium, rhydrogen, rmagnesium)
• Major relectrolytes rin rthe rECF rinclude rsodium, rchloride, rcalcium, rbicarbonate
• Major relectrolytes rin rthe rICF rinclude rpotassium, rphosphorus, rmagnesium
Regulation rand rHomeostatic rMechanism rof rFluid rand rElectrolyte rBalance
• Osmosis
o Major rmethod rof rtransporting rbody rfluid
o Movement rof rwater r(or rother rsolute) rfrom ran rarea rof rlesser rto rone rof
rgreater rconcentration
• Diffusion
o Passive rmovement rof relectrolytes ror rother rparticles rdown rthe rconcentration
gradient r(from rhigher rto rlower rconcentration)
• Active rtransport
o Movement rof rions ragainst rosmotic rpressure rto ran rarea rof rhigher rpressure;
requires renergy
• Capillary rfiltration
o Movement racross ra rmembrane, runder rpressure, rfrom rhigher rto rlower rpressure
Osmosis, rDiffusion rand rActive rTransport
,Filtration rand rOsmosis
Osmolarity rand rIV rFluid
• Normal rserum r(blood0 rosmolality=275-295 rmOsm/L
• Isotonic rsolution: rA rsolution rthat rhas rosmolarity requal rto rserum r(blood)
• Hypotonic rsolution: rA rsolution rthat rhas rLOW rosmolarity ris rone rthat ris r<serum rosmolarity
• Hypertonic rsolution: rA rsolution rthat rhas rHIGH rosmolarity ris rone rthat ris
r?serum rosmolarity
IV rFluid-Isotonic
• Total rosmolality rclose rto rthat rof rthe rECF; rreplace rECF
• 0.9% rSodium rChloride r(NS- rnormal rsaline)
• Lactated rRinger’s rSolution
o Has rthe rsame rosmolality ras rblood rsolutions ron rboth rsides rof rthe rsemipermeable
membrane rare requal rin rconcentration. rExpand rthe rblood rvolume rwithout
rcausing ra rshift rfrom rone rcompartment rto ranother
o Expands rECF rand rICF rvolume
o Used rto rtreat rfluid rvolume rdeficit rfrom rhemorrhage, rsevere rvomiting
rand rdiarrhea, rheavy rdrainage rfrom rGI rsuction, rfistulas rand rwounds;
r1st rline rresuscitation rfluid
IV rFluid-Hypotonic
• Hypotonic rto rplasma; rreplace rICF
• 0.45% rNS(1/2-strength rnormal rsaline)
• 0.33% rNS(1/3-strength rnormal rsaline)
o A rsolution rof rlower rosmotic rpressure rmoves rfluid rinto rthe rcells, rcausing rthem rto
expand. rShift rECF rto rICF rwith rdecrease rin rECF
o Used rto r“dilute” rplasma rparticularly rin rhypernatremia
o Treats rcellular rdehydration r(as rin rdiabetic rketoacidosis) rand rhypernatremia
r(high rserum rNa+)
o Do rnot ruse rfor rpatients rwith rincreased rintracranial rpressure rrisk ror rthird
rspacing rrisk rincreased rfluid rto rbrain rcells rand rthird rspace
o Can rworsen rexisting rhypovolemia rand rhypotension-fluid rpulled rout rof rIVC
, IV rFluid-Hypertonic
• Hypertonic rto rplasma
• 3%, r5% rNS
• D5% rin rNS
• D5% rin rLR
• D10% rin rwater r(D10W), rD20%, rD50%
o A rsolution rof rhigher rosmotic rpressure-pulls rfluid rfrom rthe rcells, rcausing rthem
shrink. rShift rICF rto rECF rwith rdecrease rin rICF
o Used rto rtreat rsevere rhyponatremia r(low rserum rNa+), rSIADH rand rcerebral redema
o Fosters rnormal rBP rand rgood rurinary routput r(often rused rpostoperatively)
o Not rused rfor rrenal ror rcardiac rdisease. rWHY??
Regulation rof rFluid rand relectrolytes
• Hypothalamus-The ramount rof rfluid rthe rbody rdesires ris rmonitored rby rthe rthirst
rresponse, rwhich ris rcontrolled rby rthe rhypothalamus, rthirst rreceptors
r(osmoreceptors) rcontinuously rmonitor rserum rosmolality r(concentration). rIf rit rrises,
rthirst rmechanism ris rtriggered
• Pituitary rregulation- rposterior rpituitary rreleases rADH r(antidiuretic rhormone) rin
rresponse rto rincreasing rserum rosmolality. rCauses rrenal rtubules rto rretain rH2O. rAs
rwater ris rretained
in rthe rvascular rspace, rvascular rvolume rand rblood rpressure rincrease
• CV rsystem-pumps rfluid rand rnutrients rthroughout rbody
o Secretes rAtrial rNatriuretic rPeptide r(ANP) rwhen rblood rvolume rof rBP ris relevated rto
inhibit rreabsorption rof rNa rand rH2O r> rdecrease rfluid rvolume rand rdecrease rBP
• Lungs- rregulate rfluid rby rreleasing rfluid rby rreleasing rwater ras rvapor rwith revery rexhalation
• Small rintestine-absorb r85% rto r95% rof rfluid rfrom ringested rfood rand rdelivers rit rinto
rthe rvascular rsystem
• Renal rregulation- rKidneys rare rthe rmaster rchemists rof rthe rbody rand rmajor
rregulator rof rfluid routput
o Filter r170 rto r180 rL rof rplasma rdaily
o Nephron rreceptors rsense rlow rosmolality rand rkidney rsecretes rrenin
o Renin-Angiotensin-Angiotensin r I-Angiotensin r II
o Angiotensin rII rcauses rNa rand rH2O rretention rby rkidneys, rvasoconstriction
rand rstimulates radrenal rcortex rto rsecrete rAldosterone rwhich rcauses
rkidneys rto rexcrete rK+ rand rH+ rand rretain rNa rand rH2O
Fluid rVolume rDeficit- rFVD r(commonly rknown ras rHypovolemia)
• Loss rof rboth rH2O rand relectrolytes r(mainly rNa+) rfrom rECF- risotonic rfluid rloss
• Causes
o Severely rdecreased rintake rof rH2O rand rsalt
o Increased routput
▪ Loss rof rblood/plasma-hemorrhage, rburns
▪ GI rlosses-vomiting, rdiarrhea, rtubes
▪ Renal rlosses-diuretic, rdiseases
Fluid and electrolytes
Fluid Facts
• Water- primary body fluid and most critical element; the fundamental solvent for all
biochemical processes in the body
• Total body water or fluid comprises about 50-40% avg. adult weight
• Loss of 5-10% body fluid=SERIOUS
• Loss of 15-20% body fluid=may be FATAL
• Fluid gained each day should=fluid lost each day (2-3L/day average)
Fluid Compartments
• Intracellular Fluid:
o =Fluid within cells
o -2/3 (70%) of total body water
• Extracellular Fluid (ECF)=Fluid outside of cells
o -1/3 (30%) of total body water
o 3 divisions:
▪ Interstitial (fluid that surrounds tissue cells including lymph)
▪ Intravascular/plasma (liquid part of the blood)
▪ Transcellular (minor compartment)
Variations in Fluid Content
• Fat has a tiny amount of water; lean tissue (muscle) has lots of water
• Females have less body fluid than males
• Age variations exist rin rregards rto rwater rcontent rof rfluid rcompartments
o Older radults r(after rthe rage rof r60) rhave rless rpercentage r(45%) rof rbody rfluid
o Infants rhave rmore rtotal rbody rfluid rand rECF rthan radults=605 rof rH2O ris
rfounf rin rECF, r40% rof rH2O ris rfound rin rICF
• What rmight rthis rmean rin rregards rto rfluid rloss rfor ran rinfant?
• What rage rgroups rat rhigher rrisk rfor ralterations rin rbalance?
Fluid rBalance rExample
• How rto rcalculate rnet rfluid rintake rand rnet rfluid routput?
o A rclient rdrinks r1000 rmL r(I) rof rwater, reats rfood rcontaining r500 rmL rof rwater r(I), rand
the rclient rvomits r250 rml r(O) remesis rover r24 rhours. rThe r24-hour rnet rgastric
rfluid rintake ris: r1000(I) r+ r500(I) r-250(O)=1250 rmL
o Another rclient rhas ra rNG rtube rin rplace. rThe rNG rirrigation rfluid ris r200 rmL r(I),
rthe rNG rdrainage routput ris r1300 rmL(O), rand rthe remesis ris r300 rmL r(O) rover
r24 rhours. rThe r24-hour rnet rgastric rfluid routput ris r1300(O) r+ r300(O) r-200(I)=
r1400 rmL
,Electrolytes
• Works rwith rfluid rto rkeep rthe rbody rhealthy rand rin rbalance
• They rare rsolutes rthat rare rfound rin rvarious rconcentrations rand rmeasures rin
rterms rof rmilliequivalents r(mEq) runit
• Can rbe rnegatively rcharged r(anions) ror rpositively rcharged r(cations)
• For rhomeostasis rbody rneeds: rTotal rbody ranions r(e.g. rchloride, rbicarbonate, rphosphate)
=Total rbody rcations r(e.g. rsodium, rpotassium, rcalcium, rhydrogen, rmagnesium)
• Major relectrolytes rin rthe rECF rinclude rsodium, rchloride, rcalcium, rbicarbonate
• Major relectrolytes rin rthe rICF rinclude rpotassium, rphosphorus, rmagnesium
Regulation rand rHomeostatic rMechanism rof rFluid rand rElectrolyte rBalance
• Osmosis
o Major rmethod rof rtransporting rbody rfluid
o Movement rof rwater r(or rother rsolute) rfrom ran rarea rof rlesser rto rone rof
rgreater rconcentration
• Diffusion
o Passive rmovement rof relectrolytes ror rother rparticles rdown rthe rconcentration
gradient r(from rhigher rto rlower rconcentration)
• Active rtransport
o Movement rof rions ragainst rosmotic rpressure rto ran rarea rof rhigher rpressure;
requires renergy
• Capillary rfiltration
o Movement racross ra rmembrane, runder rpressure, rfrom rhigher rto rlower rpressure
Osmosis, rDiffusion rand rActive rTransport
,Filtration rand rOsmosis
Osmolarity rand rIV rFluid
• Normal rserum r(blood0 rosmolality=275-295 rmOsm/L
• Isotonic rsolution: rA rsolution rthat rhas rosmolarity requal rto rserum r(blood)
• Hypotonic rsolution: rA rsolution rthat rhas rLOW rosmolarity ris rone rthat ris r<serum rosmolarity
• Hypertonic rsolution: rA rsolution rthat rhas rHIGH rosmolarity ris rone rthat ris
r?serum rosmolarity
IV rFluid-Isotonic
• Total rosmolality rclose rto rthat rof rthe rECF; rreplace rECF
• 0.9% rSodium rChloride r(NS- rnormal rsaline)
• Lactated rRinger’s rSolution
o Has rthe rsame rosmolality ras rblood rsolutions ron rboth rsides rof rthe rsemipermeable
membrane rare requal rin rconcentration. rExpand rthe rblood rvolume rwithout
rcausing ra rshift rfrom rone rcompartment rto ranother
o Expands rECF rand rICF rvolume
o Used rto rtreat rfluid rvolume rdeficit rfrom rhemorrhage, rsevere rvomiting
rand rdiarrhea, rheavy rdrainage rfrom rGI rsuction, rfistulas rand rwounds;
r1st rline rresuscitation rfluid
IV rFluid-Hypotonic
• Hypotonic rto rplasma; rreplace rICF
• 0.45% rNS(1/2-strength rnormal rsaline)
• 0.33% rNS(1/3-strength rnormal rsaline)
o A rsolution rof rlower rosmotic rpressure rmoves rfluid rinto rthe rcells, rcausing rthem rto
expand. rShift rECF rto rICF rwith rdecrease rin rECF
o Used rto r“dilute” rplasma rparticularly rin rhypernatremia
o Treats rcellular rdehydration r(as rin rdiabetic rketoacidosis) rand rhypernatremia
r(high rserum rNa+)
o Do rnot ruse rfor rpatients rwith rincreased rintracranial rpressure rrisk ror rthird
rspacing rrisk rincreased rfluid rto rbrain rcells rand rthird rspace
o Can rworsen rexisting rhypovolemia rand rhypotension-fluid rpulled rout rof rIVC
, IV rFluid-Hypertonic
• Hypertonic rto rplasma
• 3%, r5% rNS
• D5% rin rNS
• D5% rin rLR
• D10% rin rwater r(D10W), rD20%, rD50%
o A rsolution rof rhigher rosmotic rpressure-pulls rfluid rfrom rthe rcells, rcausing rthem
shrink. rShift rICF rto rECF rwith rdecrease rin rICF
o Used rto rtreat rsevere rhyponatremia r(low rserum rNa+), rSIADH rand rcerebral redema
o Fosters rnormal rBP rand rgood rurinary routput r(often rused rpostoperatively)
o Not rused rfor rrenal ror rcardiac rdisease. rWHY??
Regulation rof rFluid rand relectrolytes
• Hypothalamus-The ramount rof rfluid rthe rbody rdesires ris rmonitored rby rthe rthirst
rresponse, rwhich ris rcontrolled rby rthe rhypothalamus, rthirst rreceptors
r(osmoreceptors) rcontinuously rmonitor rserum rosmolality r(concentration). rIf rit rrises,
rthirst rmechanism ris rtriggered
• Pituitary rregulation- rposterior rpituitary rreleases rADH r(antidiuretic rhormone) rin
rresponse rto rincreasing rserum rosmolality. rCauses rrenal rtubules rto rretain rH2O. rAs
rwater ris rretained
in rthe rvascular rspace, rvascular rvolume rand rblood rpressure rincrease
• CV rsystem-pumps rfluid rand rnutrients rthroughout rbody
o Secretes rAtrial rNatriuretic rPeptide r(ANP) rwhen rblood rvolume rof rBP ris relevated rto
inhibit rreabsorption rof rNa rand rH2O r> rdecrease rfluid rvolume rand rdecrease rBP
• Lungs- rregulate rfluid rby rreleasing rfluid rby rreleasing rwater ras rvapor rwith revery rexhalation
• Small rintestine-absorb r85% rto r95% rof rfluid rfrom ringested rfood rand rdelivers rit rinto
rthe rvascular rsystem
• Renal rregulation- rKidneys rare rthe rmaster rchemists rof rthe rbody rand rmajor
rregulator rof rfluid routput
o Filter r170 rto r180 rL rof rplasma rdaily
o Nephron rreceptors rsense rlow rosmolality rand rkidney rsecretes rrenin
o Renin-Angiotensin-Angiotensin r I-Angiotensin r II
o Angiotensin rII rcauses rNa rand rH2O rretention rby rkidneys, rvasoconstriction
rand rstimulates radrenal rcortex rto rsecrete rAldosterone rwhich rcauses
rkidneys rto rexcrete rK+ rand rH+ rand rretain rNa rand rH2O
Fluid rVolume rDeficit- rFVD r(commonly rknown ras rHypovolemia)
• Loss rof rboth rH2O rand relectrolytes r(mainly rNa+) rfrom rECF- risotonic rfluid rloss
• Causes
o Severely rdecreased rintake rof rH2O rand rsalt
o Increased routput
▪ Loss rof rblood/plasma-hemorrhage, rburns
▪ GI rlosses-vomiting, rdiarrhea, rtubes
▪ Renal rlosses-diuretic, rdiseases
