Transcript FLUIDS AND ELECTROLYTES

FLUIDS AND
ELECTROLYTES
Terms to KNOW
• Total Body Water (TBW)
• Intracellular fluid
• Extracellular fluid
• Intravascular fluid
• Interstitial fluid
• Solvent
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Electrolyte
Dissociate
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cation
Anion
Buffer
Isotonic
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Hypotonic
Osmotic gradient
Diffusion
Osmosis
Active transport
Facilitated diffusion
Osmolality
• Osmolarity
• Osmotic pressure
• pH
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PaO2
PaCO2
HCO3Acidosis
Alkalosis
Metabolic Acidosis
Respiratory Acidosis
Respiratory Alkalosis
WATER
• Most abundant substance in the body
• Aprox. 60% of TBW
• 70 kg adult (154 lbs) TBW aprox. 42L (11
gallons)
Water distribution
Various compartments all separated by a
cell membrane
• Intracellular fluid (ICF)
Fluid inside body cells
Largest compartment
Contains 75% of TBW
Extracellular Fluid (ECF)
• All of the fluid found outside the body’s
cells
• Contains the 25% of TBW
• Two divisions
intravascular fluid
interstitial fluid
Intravascular Fluid
• Outside the cells, within the circulatory
system
• Pretty much the same as blood plasma
Interstitial Fluid
• Outside the cell membranes but outside
the circulatory system
Examples of Interstitial Fluid
• Synovial fluid
• Aqueous humor of the eye
• Secretions
Water is a universal solvent
• Solvent
dissolves other substances yeilding a
solution
ELECTROLYTES
• when placed in water dissociates into
electrically charged particles or IONS
Cation
• Positively charged ion
Anion
• Negatively charged ion
Cations in our body
Sodium
• Na+
• Common in extracellular fluid
• Regulates the distribution of water
WATER FOLLOWS SALT
• Transmission of nervous impulses
Potassium
• K+
• Prevelent in extracellular fluid
• Transmission of electrical impulses
Calcium
• Ca++
• Muscle contraction
• Nervous impulse transmission
Magnesium
• Mg++
• Several biochemical processes
enzymes require magnesium to
function
ATP, DNA and RNA also need
Magnesium
Anions in our body
Chloride
• Cl• Balances cations
• Renal function
• Closely associated with sodium
Bicarbonate
• HCO3• Primary buffer
Phosphate
• HPO4• Energy stores
• Buffer primarily in the intracellular space
OSMOSIS AND DIFFUSION
• Cells have semipermeable membranes
• When the concentration of fluid is equal on
both sides of the membrane this is
ISOTONIC
• When the concentration of fluid is less on
one side of the membrane this is
HYPOTONIC
• When the concentration of fluid is greater
on one side of the membrane this is
HYPERTONIC
• The difference in concentration is the
OSMOTIC GRADIENT
• There is a shift to maintain homeostasis or
a state of equilibrium
• Molecules will normally move to an area of
higher concentration to that of lower
concentration which is DIFFUSION
• Diffusion does not require E
• Water, which moves faster than
electrolytes moves across the membrane
to dilute the higher concentration of
electrolytes
Osmosis
The movement of any solvent across the
membrane
Active Transport {requires E}
• Movement against the osmotic gradient
less concentrated to more concentrated
area
i.e.
The inside of a myocardium cell must be
negatively charged. Sodium being
positively charged diffuses passively into
the cell.
Sodium ions are pumped out of the cell
while potassium is pumped into the cell
More sodium than potassium is moved
achieving equillibrium
• Facilitated diffusion
Requires the assistance of a helper protein
to move into the cell
An example is Glucose
Osmolality
• The concentration of solute per Kg
• The movement of water and solutes
across the cell membrane maintains a
state of equilibrium of osmolality
Osmolarity
• The concentration of solute per L of water
• Sodium maintains osmolality in the
extracellular space
• Potassium maintains omolality in the
intracellular space
ACID-BASE BALANCE
Acid-Base Balance
• The regulation of H+ in the body
• H+ Is acidic
• A deviation has an adverse affects on all
biochemical functions of the body
pH
• Potential of Hydrogen
• Through metabolism and other
biochemical processes, H+ is constantly
produced
Normal pH is 7.35 to 7.45
<7.35 = Acidosis
>7.45 = Alkalosis
THREE FORMS OF REGULATION
Bicarbonate Buffer System
• The fastest
• The players [in equilibrium with H+ ]
Bicarbonate {HCO3-}
Carbonic Acid {H2CO3-}
• Either H+ will combine with bicarbonate ion
to produce carbonic acid
or
Carbonic acid will dissociate into
bicarbonate ion and hydrogen ion
• Erythrocytes contain have an enzyme
called carbonic anhydrase which converts
carbonic acid into CO2 and H2O and this
occurs very rapidly
• Most buffering occurs in the erythrocytes
Respiration
| two other mechanisms
Kidney function| of regulation
Respiration
• An increase blows off CO2 thus decreases
H+ thus decreases pH
Kidneys
• Modifies the concentration of HCO3- in the
blood
• Increased elimination of HCO3- lowers pH
• Decreased elimination of HCO3- raises pH
The kidneys achieve acid-base balance by
removing or retaining certain chemicals
So what is the significance of all this?
The bottom line is to determine:
• If a patient is in a state of acidosis
• If a patient is in a state of alkalosis
• If the disturbance is respiratory in nature
• If the disturbance is metabolic in nature
In order to make this determination we must
know the norms
• pH
7.35 to 7.45
• PaCO2
35 to 45 mm Hg
• HCO322 to 26 mEq/L
• PaCO2
75 to 100 mm Hg
The first determination is if the patient is in a
state of acidosis or alkalosis
• <7.35 Acidosis
• >7.45 Alkalosis
Next is to determine if the disturbance is
respiratory or metabolic in nature
Assess the PaCO2 level
• If respiratory the PaCO2 should rise as the
pH falls {acidosis} conversely the PaCO2
should fall as the pH rises
SO…….
If the pH and PaCO2 are moving in opposite
directions then the disturbance is
respiratory
To determine if the disturbance is metabolic
in nature the HCO3- is considered
• As pH increases, so should the HCO3• The opposite is true
Thus
If the pH and HCO3- is moving in the same
direction then the disturbance is metabolic
in nature
Ph
PaCO2
7.35-7.45
35-45
Respiratory
Acidosis
Fall
Rise
HCO322-26
Normal
Respiratory
Alkalosis
Rise
Fall
Normal
Metabolic
Acidosis
Fall
Normal
Fall
Metabolic
Alkalosis
Rise
Normal
Rise
Ph
7.22
Respiratory
Acidosis
Respiratory
Alkalosis
Metabolic
Acidosis
Metabolic
Alkalosis
PaCO2
55
HCO325
Ph
7.22
Respiratory
Acidosis
Respiratory
Alkalosis
Metabolic
Acidosis
Metabolic
Alkalosis
PaCO2
55
decreased increased
HCO325
normal
pH
7.50
Respiratory
Acidosis
Respiratory
Alkalosis
Metabolic
Acidosis
Metabolic
Alkalosis
PaCO2
42
HCO333
pH
7.50
PaCO2
42
HCO333
increased
normal
increased
Respiratory
Acidosis
Respiratory
Alkalosis
Metabolic
Acidosis
Metabolic
Alkalosis
COMPENSATION
• Remember with the buffering systems the
body attempts to regulate hence a state of
compensation
uncompensated
partially compensated
fully compensated
• In a state of uncompensated or partially
compensated the ph is still abnormal
• In full compensation the pH is normal but
other values may not be
Partial Compensation
• Assess the pH
this step is unchanged
• Assess the PaCO2
remember the pH and PaCO2 should
be moving opposite
If however they are moving in the same direction
would indicate a metabolic disturbance
If as an example the PaCO2 was decreasing
it would mean the body was blowing off
CO2 in order to return pH to normal limits.
Meaning the respiratory system is acting
as a buffer system
As evidenced that this is actually metabolic
in nature then plugging in the PaCO2
moving in the same direction………
The determination then would be a metabolic
disturbance with partial respiratory
compensation
• Assess the HCO3- which moves in the same
direction as the pH
If they move in the opposite direction, the
disturbance would actually be respiratory in
nature with the kidneys acting as the buffer
system by retaining HCO3- .
TO SUMMARIZE
Fully
Compensated
Ph
PaCO2
7.35-7.45
35-45
Respiratory
Acidosis
Normal
but <7.40
Rise
HCO322-26
Rise
Respiratory
Alkalosis
Normal
but >7.40
Fall
Fall
Metabolic
Acidosis
Normal
but <7.40
Fall
Fall
Metabolic
Alkalosis
Normal
but >7.40
Rise
Rise
Partially
Compensated
Ph
PaCO2
7.35-7.45
35-45
Respiratory
Acidosis
Fall
Rise
HCO322-26
Rise
Respiratory
Alkalosis
Rise
Fall
Fall
Metabolic
Acidosis
Fall
Fall
Fall
Metabolic
Alkalosis
Rise
Rise
Rise
• The only difference between fully
compensated and partially compensated is
whether the pH has returned to within the
normal range
RESPIRATORY ACIDOSIS
• Causes [hypoventilation]
Head injury
Narcotics
Sedatives
Spinal cord injury
Neuromuscular disease
Atelectasis
Pneumonia
Pneumothorax
Pulmonary edema
Bronchial obstruction
Pulmonary embolus
Pain
Chest wall injury or deformity
Abdominal distension
Signs and symptoms of respiratory acidosis
• Dyspnea
• Respiratory distress
• Headache
• Restlessness
• Confusion
• Drowsiness
• unresponsiveness
• Tachycardia
• Dysrhythmias
Respiratory Alkalosis
Causes [hyperventilation]
• Anxiety
• Fear
• Pain
• Fever
• Sepsis
• pregnancy
Signs and Symptoms
• Light-headedness
• Numbness/tingling
• Confusion
• Inability to concentrate
• Blurred vision
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Dysrythmias
Palpitations
Dry mouth
Diaphoresis
Spasms of arms and legs
Metabolic Acidosis
Causes
• Renal failure
• DKA
• Anaerobic metabolism
• Starvation
• Salicylate intoxication
Signs and Symptoms
• Headache
• Confusion
• Restlessness into lethargy
• Kusmal respirations
• Warm flushed skin
• Nausea and vomiting
Metabolic Alkalosis
Causes
• Antacids
• Overuse of bicarbonate
• Lactate as used in dialysis
• Protracted vomiting
• Gastric suction
• High levels of aldosterone
Signs and symptoms
• Dizziness
• Lethargy
• Disorientation
• Seizure
• Coma
• Weakness
• Muscle twitching
• Muscle cramps
• Tetany
• Nausea and vomiting
• Respiratory depression
• Tetany
Involuntary contraction of muscles
• Proracted
Prolonged
• Aldosterone
a hormone that increases the reabsorption
of sodium ions and water and the release
of potassium ions
• Atelectasis
the lack of gas exchange within alveoli, due
to alveolar collapse or fluid