Fluids & Electrolytes Flashcards
Hyperkalemia
Serum K+ > 5.5mEq
Sx of Hyperkalemia
Fatigue
Muscle weakness
EKG changes—> potentially life threatening arrythmias
Risk for sever negative outcomes increases as K+ levels increase
Causes of Hyperkalemia
Decreased renal excretion (renal failure)
Heart failure (due to decreased renal function)
Increased K+ intake
Shift of K+ from IC—> EC via
Β adrenergic blockade
Insulin deficiency
Acidosis
Medications that increase serum K+ (7)
Potasium sparing diuretics
ACE
NSAIDS
Digoxin Toxicity
ARBs
Sulfamethoxazole/Trimethoprim
If a patient has moderate elevation of serum K+ WITHOUT EKG changes, how would you treat his hyperkalemia?
Increase excretion of K+ via cation exchange resin or diuretics
Goals of treatment for a patient with severe (>6.5) hyperkalemia
Immediate stabilization of myocardial membrane
Rapid shifting of K+ to ICS
Increase K_+ elimination (d/c exogenous K+)
What is the medication and dose that is given to someone with SEVERE HYPERKALEMIA to stabilize their myocardial cell membrane?
IV Calcium 1g IVPG over 1 hour (IV piggy back)
**Calcium Gluconate preferred
Why is Calcium Gluconate preferred over calcium carbonate?
Calcium Carbonate—> Brady cardia and increased tissue damage & extravasation
What do we check within 30min-1 hour of administering IV insulin to a patient with hyperglycemia and why?
Check BG; because Insulin can cause hypoglycemia
Why do we give insulin to a patient with hypglycemia?
Shifts K+ from ECS—> ICS
When do we treat hyperkalemia with sodium bicarb
In the setting of acidosis
What does sodium bicarb do to treat hyperkalemia?
Shifts K+ from ECS to ICS
Raises systemic pH
What is the dose of sodium bicarb given to patients with hyperkalemia who are in acidosis?
50 mEq IV
What do Β 2 agonists do in the setting of hyperkalemia (2)?
Shift K+ from ECS—> ICS BY:
1) stimulating NaK-ATPase to promote intracellular K+
2) stimulates pancreatic B-receptors to increase insulin secretion
What β-2 agonist is used to treat severe hyperkalemia and how much?
Albuterol 10-20mg via nebula er over 10 min
Why are β-2. Agonists not recommended as solo treatment for hyperkalemia?
Some patients are resistant to the effects
Who are β-2 agonists less effective in?
Patients already on a non selective β blocker
Why are loop diuretics used in the setting of hyperkalemia?
They promote K+ excretion
What 2 loop diuretics are used in the setting of hyperkalemia? What are their doses?
Furosimide: 40-80mg IV
Bumetanide 2-4mg IV
When may loop diuretics be less effective in treating hyperkalemia?
Severe renal failure
How does SPS work to treat hyperkalemia?
Binds potassium in the GI tract to reduce absorption and increase elimination
Resting passes through intestines—> SPS exchanges 1mEq of Na+ for 1mEq K+ (1:1 equal exchange)
Why cant SPS be used ALONE in life- threatening hyperkalemia?
Takes too long to work
Onset= >2 hours
Who should we avoid using SPS in?
Patients with bowel problems
Since SPS works best when in the colon what cathartic is most commonly given with it?
Sorbitol
Sodium Zirconium Cyclosilicate
Potassium binder
Exchanges K+ for Both H+ and Na+
Onset:1 hr
Patiromer
Potassium binder
Exchanges Ca+ for K+
Onset: 7 hrs
What are the 3 potassium binders
Sodium polystyrene sulfonate
Sodium zirconium Cyclosilicate
Paritomer
What is the treatment of choice for hyperkalemia when pharmacologic treatments fail?
Dialysis
Definition of hypokalemia
Serum K+ <3.5
Causes of hypokalemia
Decrease in K+ intake
Increase in K+ loss (diuretics)
Excess GI loss (v/d)
Shifts from ECS (β adrenergic agents, insulin, alkalosis)
Signs and symptoms of hypokalemia
Often asx
Sx are nonspecific and predominantly related to muscular or cardiac function:
- weakness and fatigue
- muscle cramps and pain
- palpitations
- psychological sx
- EKG changes
- Dysrhythmias
- hypotension
What are the goals of treatment for hypokalemia?
Reduction of K+ losses
Replenishment of K+ stores
Methods of reduction of potassium loss?
D/c diuretics./ laxatives
Use K+ sparing diuretics
Treat diarrhea and vomiting
What methods can be used for K+ replenishment of MILD hypokalemia
Oral
What methods can be used for replenishment of K+ in MODERATE hypokalemia?
IV or Oral
What method can be used for K+ replenishment in SEVERE hypokalemia?
IV
Most commonly used salt in treatment of hypokalemia
KCl-
Serum K+ will increase ________ for every __________mEq of supplementation
.1mEq/L for ever 10mEq
T/F: oral and Parenteral K+ CANOT be used simultaneously
False
Try to limit oral single doses to 10-20mEq due to the risk of __________
GI irritation
Infusions >10mEq of Serum K replenishment require ______________
EKG monitoring
____________ is necessary for K+ uptake therefore it must be checked and replaced as needed in order to correct the potassium levels
Magnesium
Hyponatremia
Sr Na+ <135mEq/L
Mild Hyponatremia
Sr Na+ 130-134mEq
Moderate Hyponatremia
Sr Na+ of 120-129mEq/L
Severe Hyponatremia
Sr. Na+ <120mEq/L
Causes of Hyponatremia
Advanced kidney disease
SIADH
Heart Failure
True Volume depelation (Na and water loss GI tract or urine)
Medications- diuretics
S&S of mild Hyponatremia
Nausea and malaise
Sx of severe Hyponatremia
Lethargy
Decreased level of conciousness
Headache
(If severe) seziures and coma
Overt neurologic sx most often are due sodium levels that are:
<115mEq/L
Over neurologic sx most often are due to very low serum levels (usually <115mEq/L) resulting in ___________________
Resulting in Intracerebral osmotic fluid shifts and brain edema
What are the 2 treatments for Hyponatremia?
Tolvaptan
3% (hypertonic) saline
Indications for Tolvaptan
Clinically significant hypervolemic or euvolemic Hyponatremia
Less marked Hyponatremia that is SYMPTOMATIC AND RESISTANT to fluid restriction (pt with HF & SIADH)
Euvolemic Hyponatremia
Low Na lev les with normal extracellular volumes and no signs of edema of Ascites
SIADH
Hypervolemic Hyponatremia
Low Na levels with greatly elevated extracellular volume (pitting edema and Ascites)
HF and cirrhosis
MOA of Tolvaptan
Vasopressin (Anti-Diuretic Hormone) antagonist
HF:
blocks the action of ADH at the V2 receptor resulting in decreased free water reabsorption in the kidney. This results in an AQUARESIS which is free water loss without electrolyte loss
Initiate and reinitiate tolvaptan in patient where and why?
In the hx; Na+ needs to be closely monitored
when is Tolvaptan NOT indicated for use?
when the patient needs urgent treatment for hyponatremia to treat serious neuro probelems
Do not use tolvapan for >30 days due to
risk of hepatotoxicity
what do we monitor in patients on tolvaptan
Serum Na+ concentration
Rate of Sr. Sodium increase
Indications of use for 3% hypertonic saline
- Severe Hyponatremia (<115)
- If patient bceomes symptomatic
Danger of using 3% Hypertonic saline
overcorrection of sodium–> osmotic demyelination syndrome (ODS)
ODS
occurs when the damage to the myelin sheath is caused by an acute decrease in brain cell volume
How does overcorrection of hyponatremia with 3% saline cuase ODS>
if Na+ correction done too quickly–> rapid fall in brain volume–> astrocytes need to replace osmolytes to pull volume back into the brain (SLOWER PROCESS)
Brain cant catch up with the rapid need for osmolytes
rapid fall in brain volume–> demylination
ODS is rare when intial serum sodium is __________________-
> 120mEq/L
Risk factors for ODS
Serum sodium <120 mEq/L
Hyponatremia for 2-3 days +
Clinical Manifestations of ODS
Behavioral disturbances
Movement disorders
Seziures
Coma
Quadraparesis
How long does it take for the sx of ODS to arise
2-6 days after overcorrection—> irreversible
Safe rate to administer hypertonic saline to avoid ODS
Avoid increase more than 12 mEq/L in 24 hrs
Usual rate= .5-1mEq/L PER HOUR
MONITOR SERUM SODIUM LEVELS (some recommendations call for every 2-3 hrs)
What is hyppmagnesemia
Serum magnesium <1.5mg/dL
Mild-moderate hypomagnesemia
1.2-1.5mg/dL
Severe hypmagnesemia
<1.2mg/dL
Causes of Hypomagnesemia
Excessive GI loss
Malnutrition
Renal Loss
Sepsis
Alcoholism
S&S Of hypomagmesemia
Sinus tachy, SVT, ventricular arrythmias
Muscle weakness
Ataxia
Vertigo
Tetany
Seizures
Irritability, delerium. Psychosis
Treatment of severe hypomagnesemia typically recommends
IV replacement 1-2g MAG SULFATE IVPB over 1 hour
Mild-moderate hypomagnesemia treatment route options
IV or Oral
What is the issue with oral agents for hypomagnesemia
All suffer from limited bioavailability
SE such as GI discomfort and diarrhea
Indications of fluid management
Expand IV volume
Correct an imbalance in fluid or electrolyte
Manage Fluid and electrolyte needs in an ongoing disease state
Maintenance
What are the 2 types of IV fluids?
Crystalloids
Colloids
What are the fluids of choice when resuscitating a patinet?
Crystalloids
Crystalloids
Aqueous solutions of ions with or without glucose that flow easily across the cell membrane
What are the Crystalloids IV Fluids
D5W
D10W
D20W
D50W
1/2 NS
3%NS
NS
D51/4NS
D51/2MS
D5NS
D5LR
LR
.9% NaCl-NS (Normal saline) is used to treat what?
fluid deficit, shock, mild Hyponatremia and for resuscitation
When you administer 1L of NaCl.9% how much stays in the Intravascular space?
250ml
What is used for replacement of pure water deficits and maintenance fluids for patients on Na+ restriction?
D5W
D5W
Provides water to ICS and ECS WITH CALORIES
Helpful in dehydration
Why is D5W not a good option for fluid resuscitation?
1L of D5W only 100mL remain in the intravascular space—> only get 100ml fluid expansion
Why do we avoid giving D5W to patients with neurologic injury and elevated ICP?
Bc D5W can freely cross al barriers—> will further increase ICP
Contents of Lactated solution (LR)
Sodium
Potassium
Chloride
Bicarb
What is LR used for
GI fluid losses
Fistula drainage
Burn and Trauma fluid loss
LR is preferred in…
Surgery and Trauma patients
When 1L of LR is administered, how much remains in the intravascular space?
250ml
Is LR good for fluid resuscitation?
Yes
Indications for .45% NaCl (1/2NS)
For patients with intracellular dehydration caused by hypernatremia or DKA
What is the maintenance fluid for someone with HTN
1/2 NS (esp when dont want to give them all the sodium in NS)
Isotonic Fluids
.9% NaCl- NS
D5W
LR
1.2NS
What are the hypertonic Crystalloids
3.0-%NACL
D5W w/ NS or 1/2 NS
D5W with LR
D10W, D20W
When are hypertonic Crystalloids used?
Hyponatremic or hypoglycemic patinets
Indications for 3% NaCl
Severe Hyponatremia
Patients with cerebral edema
TBI to reduce elevated ICP—> increase cerebral percussion pressure
How much Crystalloids do we administer for resuscitation?
500-1000mL bolus then monitor parameters
How much Crystalloids do we give for sepsis>
30mL/kg in 1st 3 hours
Maintenance IV fluids are indicated for….
Patients who are unable to tolerate oral fluids
To estimate daily fluid maintenance
1500mL for first 20KG
20mL for every KG >20
Colloids
Solutions of large molecules (typically protein or starch) that dont pass through cell membranes and remain in the intravascular compartment
Mor efficient in restoring normal intravascular volume and CO but expensive
Indications for use of colloids
When resuscitation with Crystalloids fails or is limited by clinically significant edema
Fluid resuscitation in pateints with severe intravascular fluid deficits (HEMORRHAGIC SHOCK)
Fluid resuscitation in presence of severe hypoalbuminemia or conditions associated with large protein loss (Burns)
What are the 4 types of colloids?
Albumin
Blood products
Plama protein fraction
Synthetic colloids
What are the 2 types of colloids we are responsible for knowing?
Albumin
Synthetic colloids
Indications of use for albumin
Hypovolemic shock (pts cant receive large volume load)
When would we CONSIDER albumin
Hypovolemic shock (INDICATION)
When fluid resuscitation with Crystalloids fils or when edema limits further Crystalloids admin
Main modulator of fluid distribution among the compartments of the body
Albumin
Most clinical use of HA (albumin) is based on
The capacity to act as a plasma expander
5% albumin
Used for volume expansion
Increases the circulating plasma volume BY AMT EQUAL TO THE AMOUNT INFUSED
Less risk of pulmonary edema
What is PICD?
Paracentesis-Induced circulatory dysfunction
What is the indication of 25% albumin
Following LVP >5 L of fluid
25% albumin is ___________ and pulls fluid into compartment
Hyperoncotic
Who do we avoid giving 25% albumin to>
Patients requiring fluid resuscitation—> can cause dehydration
What happens when you give someone 25% albumin
5 fold effect on patients intravascular load compared to the administered dose
Hydroxyethyl starches
Semi-synthetic colloid
Hetastarch—> highly effective as a plasma expander, less expensive
When is hetastarch used?
Used after major surgeies and burns
Problems with Hetastartch (2 )
Prolongs PT, PTT , and bleeding times
Can cause anaphylaxis
Why should we avoid giving hetastarch?
Increases risk of AKI, need for replacement therapy, and increased moraltiy in critically ill patinet
NS infusion volume and equivalent intravascular volume
1000 mL (1L)—> 250mL
LR infusion volume—>equivalent intravascular volume
1000ml (1L)—-> 250mL
5% dextrose infusion volume—> equivalent intravascular volume
1000mL (1L)—> 100mL
Albumin 5% infusion vol—> equivalent intravascular vol
500mL—> 500mL
Albumin 25% infusion volume—> equivalent intravascular vol
100mL—> 500mL
