Fluid and Electrolytes Flashcards
Vascular Access Overview
- Required to administer IV fluids and medications
- Useful in obtaining blood sampling for lab tests
- Types of access depends on medications that need to be administered and anticipated length of use
- Central vs. peripheral
- Vascular acces can be utilized for invasive monitoring in critically ill patients
Peripheral catheters
Complications?
- Most commonly used catheter in the acute care setting
- Usually placed in a vein of the hand or arm, placed distally if possible
- CDC Guidelines recommend changing of catheter every 96 hours
- Infection, Phlebitis, Extravasation, Infiltration, Air embolism, Hemorrhage, Hematoma
Peripherally Inserted Central Catheters (PICC)
- Good for patietns who are staying long IV acces
- Alternative to Subclav lines, internal jugular lines or femoral lines, which have higher rates of infection
- Insertions requires specialised training
- Complications
- Catheter occlusion, phlebitis, hemorrhage, thrombosis, infection
Central Venous Catheters
- Allows administrations of large volumes of fluid, blood products, TPN, caustics, vasopressors, chemo
- Capabe of monitoring hemodynamics CVP
- Placed into a large vein in the neck (internal jugular vein). chest or groin
- Complications
- Pneumothorax, Thrombosis, Infections, Air embolism
Intraosseous
- Entry into the bone marrow to provide a non-collapsible entry point into the systemic venous system
- Any medication that can be administered via IV can be administered via IO
- Useful in emergency situations when IV access cannot be obtained
- Requires specialized training
- EM nurses, EMT
- Can be utilized for ~24 hours
- Complicatons
- Fat embolism, fracture, osteomyelitis, compartment syndrome, Abscess, skin necrosis
Complications of IV therapy
- Infiltration
- Non-vesicant fluid leaks into surrounding tissue
- Infections
- Punture interrupts skin integrity
- Phlebitis
- Inflammation of the vein
- Thromophlebitis
- Irritation of vein with clot formation
- Extravascation
- Leakage of vesicant fluid into surrounding tissue
Comparison fo Options for Vascular Access
Total Body Water
1 liter of fluid =?
70 kg male =
- For clinical purposes, total body fluids = 60% body weight for adults
- Percent decreases as body fat increases
- decreases with Age
- For calculations, use hydrated (normal) weight unless patient is obese (>20% of IBW) use IBW
- 2.2Ibs(1 kg)
- 42 liters
Intracellular fluid
- Water within cells
- 2/3 of TBW
- 40% of body weight
- Rich in electrolytes
- K, Mg, Phosphates, Proteins
Extracellular fluid (ECF)
- Fluid outside cell
- Rich in Sodium, Chloride, bicarb
- 1/3 of TBW
- Made up of two major fluid sub compartements
- Interstitual/ lymph
- Fluid space between cells
- Intravascular
- Interstitual/ lymph
Fluids, Electrolytes, Acid-Base losses
- Sensible
- Urine, stool
- Water, sodium, K
- Insensible
- Lung, evaporation through skin, fever
- Mostly water and a little Na+
- Other
- Nasogastric tube suction
- Nasojejunal tubes
- Drains
- Fistula tracts
- Burns
Intravascular Depletion Acute problem
Signs/Symptoms and causes
TBW depletion Chronic problem
Replacement therapy Determining the Needs
- Ongoing exceptional loss
- If ongoing problems are not accounted for, a second insufficiency will develop soon after correction of the current deficiency
- Replacement regimen should match as closely as possible both the amount and composition of the exceptional losses
- At minimum, realize that exceptional fluid losses maybe be occuring and be particularly vigilant to monitor these patients for S/S of fluid depletion
Maintenance Basal Requirements
Neonate (1-10 kg)
Child (10-20)
Adults > 20
- 100 ml/kg
- 1000 ml + 50 ml for each kg > 10
- 1500 mL + 20 ml for each kg >20 ‘
- For sensible losses in hospitalized pts not taking much PO
Isotonic fluids
(310 mEq/L)
fluid doesnt shift from ECF to ICF
Hypertonic > 376 can help?
Draws water out of cells into ECF
Help stabalize bp, increase urine output, and reduce edema
Hypotonic < 250
Water is pulled from vascular compartments into interstitial fluid is diluted
Crystalloid solutions
- Electrolyte solutions supply water and sodium to maintain the osmotic gradient between ICF and ECF
- Plamsa volume- expanding capability of crystalloid is directly related to its sodium concentration
- D5W: Free water
IV fluid comparisons
IV fluid comparisons continued
Choice of approptiate fluid?
Define?
Pts with impaired tissue perfusion?
Standard therapy?
- Define primary type of fluid problem
- TBW depletion vs. ECF depletion
- ITP- immediate therpeutic goal
- Return volume to intravascular space and ECF compartment
- Standard therapy is to administer normal saline quickly (150-500 mL/hr) until S/S of impaired tissue perfusion have minimized or disappeared
- Pt may be switched to a more hypotonic solution
In pts demonstrating impaired tissue perfusion?
- LR is an alternative, however, lactate may be problematic during massive prolonged infusions
- In severe cases, a solution may be indicated that increases in oncotic pressire within the vasculature space
- Colloid
- blood cells (specially indacted if oxygen-carrying capacity of blood is compromised)
In patients with elevated plasma osmolarity and serum sodium concentrations
- In patients demonstrating elevated plasma osmolality and serum sodium concentrations
- Virtually always have a water-deficit problem and, in the absence of S/S of impaired tissue perfusion, primarily need hydration (water) therapy
- Hypotonic solutions: more efficient at replenishing the ICF than do isotonic solutions and reduce the plasma osmolality more quickly
- Solution should have a lower sodium concentration than the patient’s serum, but do not drop the serum sodium too quickly (CAUTION - cerebral edema)
- D5½ NS is a commonly-used general rehydration solution; hypertonic or colloidal solutions have no role in treating TBW depletion
Monitoring therapy
Parameters?
Therapuetic goal: resolve S/S of fluid deficit and normalize lab values as much as possible
- Physical S/S (thirst, sunken fontanelles, CNS problems)
- Orthostatic blood pressure
- Pulse rate
- Wt changes
- Blood chnages
- Blood chemistries
- FLuid input vs. fluid output
- CVP, PCWP, cardiac output (ICU pts)
Monitoring therapy?
Replenish fluids ______ in conditions that may?
Failure?
- more cautiously in conditions that may predispose a pt to fluid overload
- Renal failure
- Cardiac failure
- Hepatic failure
- Elderly
Fluid deficiency summary?
Summary - fluid overload
- Excess intake
- Excess IV fluids
- Blood/plasma use
- hypertonic fluids
- Excess dietary sodium
- Water intoxication
- Remobilization of edema
- Inadequate Output
- CHF
- Cirrhosis
- Nephrotic syndrome
- Hyperaldosteronism
- Low dietart protein
- Steroid use
Electrolyte distribution
Total # of anions = ?
Critical that cell membrane keep?
___ concentrations reflect total body stores of ECF electrolytes rather than that of ICF electrolytes
- total number of cations in each fluid compartment
- keep the ICF and ECF separate and biochem distinct
- Serum
Serum electrolyte normal values?
Sodium disorders (___- ____)
Physiology
- 135-145
- Predominant cation of the ECF
- Primary electrolyte in establishing osmostic pressure between the ICF and ECF
- All body fluids are in osmotic equilibrium and changes in serum sodium concentration (Na) are associated with shifts of water in and out of body fluid compartements
- Adding Sodium in the intravascular compartment from the interstitial fluid and, ultimately from ICF
Sodium disorder
A pts Na concentration should not be used because it doesnt reflect?
Na imbalances cannot be properly assesses without?
Na disorders are ___ disorders?
Normal sodium maintenance is?
- Not be used as an index of sodium because it does not reflect total body sodium content, Na primarily reflects disturbances in TBW
- Without first assessing the body fluid status
- Water disorder
- 80-120 meq/day
Hyponatremia: Signs and Symptoms
Usually exhibited at < 120 meq/L
Usually as <110
- Agitation
- Fatigue
- HA
- Muscle cramps
- Nausea/anorexia
- Confusion
- Seizures
- Coma
Hypertonic Hyponatremia
Usually associated with _____
Treat the ___ as this is corrected the [Na] will?
hyperglycemia
Treat the hyperglycemia na with return to normal
Diagnostic algorithm for hyponatremia
Diagnostic algorithm for hyponatremia
continued
Calculation of sodium deficit in a 75 kg male with a serum sodium of 123 mEq/L
Sodium deficit = (45 liters)(140 mEq/L - 123 mEq/L) = 765 mEq
STOPPED at HYPERNATREMIA
Causes of Hypernatremia
First 4 lead to?
5
- Dehydration = loss of hypotonic fluid (respiratory, skin losses)
- Decreased water intake
- Osmotic diuresis
- Diabetes insipidus (decreased ADH activity)
- May be induced by certain drugs (lithium, phenytoin)
- Latrogenic- Admin of too mich hypertonic saline-uncommon
Hypernatremia treatment
Calculate TBW deficit?
replace deficit over? with?
- Water def= Normal TBW - Present TBW
- Over 48-72 hours with solution hypotonic to pts serum
Hypernatremia treatment
Overly-___ correction may lead to?
The rate at which hypernatremia should be corrected depends on the severity of symptoms and the degree of?
For ____ pts, the rate of correction probably should not exceed?
Rule of thumb?
- Rapid may lead to cerebral edema and death
- Hypertonicity
- Asymptomatic, 0.5 mEq/L/hour
- Replace half the calculated deficit with hypotonic solutions over 12 to 24 hours
Hypernatremia example
Calculate the water deficit in a 75 kg patient male with a serum sodium of 156 mEq/L
Water Def (L) = TBW x [(serum sodium/140)-1]
45 x 0.1 = 5 L
Calcium disorders (__-__)
Ca and phos concentrations regulated by?
Normal calcium maintenance requirement
Corrected calcium accounts for? Calculation?
- 9-10.5 mg/dL
- Parathyroid hormone (Increased, increases calcium concentration
- Vit D
- Calcitonin increased, decreases calcium
Maintenance- 800-1200
CC- accounts for a decrease in percent of protein binding due to decrease albumin concentration
CC= observed [Ca] + 0.8 (normal albumin*-observerd albumin)
Normal = 4 g/dL
Hypocalcemia sign/symptoms and causes
Checking Trousseaus Signs?
- Apply a BP cuff to pts upper arm and inflate
- Pt will experience adducted thumb, flexed wrist and metacarpophalangeal joints
- Carpopedal spasm=tetany
Checking for Chvosteck signs
- Tap on pts focial nerve adjacent to the ear
- Brief contraction of upper lip, nose, or side of face indicated tetany
Calcium supplements
IV calcium replacement products which one is preferred and why?
How are they given?
Calcium gluconate- preferred less irritating
Calcium chloride- irritating to veins–>central line
Preparation given as slow push or added to 50 mL to 250 mL .9% NaCl, LR, D5W for slow infusion
Indications for IV calcium for Acute Hypocalcium
- Pt symptomatic (patesthesia, tetany, Chvostek sign)
- Clinically relevant hypocalcemia (serum Ca < 1 mmol/L)
- Massive blood transfusion (especially with preexisting cardiac disease)
- CCB overdose
- Receiving inotropic or vasopressor support
- Emergent hyperkalemia
Hypocalcemia treatment
Acute symptomatic hypocalcemia
- 200-300 mg of elemental calcium IV and repeat until symptoms fully controlled
- 1 gram of calcium chloride or 2-3 grams of calcium gluconate
- No faster then 30-60 mg of elemental calcium per minute
- Caution if serum phosphate elevated or if on digoxin therapy
Hypercalcemia treatment
- Consider if pt symptomatic and/or serum concentration > 12 mg/dL
- 0.9% NaCl +- furosemide
- Infusion rate as high as 200-300 ml/hr may be needed
- Only ass loop diuretic after initial ECF depletion has been corrected
- Function kidney needed (hemodialysis alternative)
- Monitor [K] and [Mg] Carefully
Treatment strategies and modalities for Hypercalcemia
Suggested treatment regimens for Hypercalcemia
- Because of polyuria, pt is usually dehydrated
- Normal saline 200-300 mL/hr, checking for continued dehydration or fluid overload. Goal: up tp 4 L on day one
- Once rehydrated, add furosemide (Block Ca reabsorption) 40-80 mg IV Q 1-4 hours until urine output = 200-250 mL/hour
- Monitor serum K and Mg
Phosphorus disorders (___-___)
Express phosphate in mg or mmoles not milliequivalents
of mmoles =
Normal maintenance phosphate requirement
- 3-4.5 mg/dL
- = amount in mg/ atomic moleculat wt
- 800-1200 mg/day (250 mg = 8 mmol)
Hypophosphatemia treatment
- Mild 2-2.5
- Eat
- Moderate 1-2.5
- Oral therapy
- 1.5-2 grams/day divided into 3-4 doses
- Diarrhea may be dose limiting
- Oral therapy
- Severe <1
- Parenteral therapy indicated
- .o8-.64 mmol/kg
- Range 5-45 over 4-12 hours
- Select replacement based on need for other electrolytes (Na vs. K)
- Caution in pts with hypercalcemia, renal dysfunction, or evidence of tissue injury
- Switch to oral supplement when level 2-2.5 mg/dL
- Parenteral therapy indicated
Phosphate replacementproducts
IV Phosphate repletion protocol
Hyperphosphatemia treatment
- Dietary restriction of phosphate and protein
- If tetany (spasms) administer calcium salts IV (see hypocalciemia aboce)
- Diaylsis of caused by renal failure
- Oral phosphate binders
- Mg hydroxide (milk of Mg)
- Can cause diarrhea
- Calcium carbonate
- Inexpensive, tablen can be crushed
- Mg hydroxide (milk of Mg)
5 phosphate binders for treating hyperphosphatemia
- Mg hydroxide (milk of Mg)
- Can cause diarrhea
- Calcium carbonate (tums)
- inexpensive, tablets can be crushed
- Calcium acetate
- 2 tabs/each meal
- Sevelamer carbonate
- Cationic polyer, contains neither Ca ot Al
- 800-1600 mg/each meal
- Lantanim carbonate
- Initial dose 250-500 mg PO 3 x daily to max 3750 mg/day
- most need 1500-3000 mg/day
K dissorders (___-___)
Normal maintenance
- 5-5 mEq/L
- 5-1 mEq/kg/day or 40-50 mEq/day
Causes of hypokalemia
Potassium supplements
Hypokalemia treatment
Moderate
Severe
- Moderate hypokalemia (2.5-3.5) without EKG change
- Usually replace orally at dose of 40-120 mEq/day
- <2.5 and or EKG change
- Initiate IV replacement
- 1 mEq fall in serum K from 4-3 is a 200 mEq deficit
- Serum K <3.0
- Total body deficit increases by 200-400 mEq for each 1 mEq reduction in serum concentration
- Initiate IV replacement
Recommended K dosage/infusion rate guideline
Hyperkalemia causes
- Increased K intake
- Excessive intake
- Blood transfusion
- Rapid excessive IV admin
- Decreased K elimination
- Renal failure
- Medications (ACEs, Bactrim, spironolactone, NSAIDs)
- Addisons disease decrease cortisol production
- K release from cells
- Tissue breakdown (surgery, trauma, hemolysis, rhabdomyolysis)
- Metabolic acidosis
- Pseudo-hyperkalemia
- Hemolyzed blood samples
Treatment of Hyperkalemia
Mg disorders (__-__)
Normal maintenance?
1.4-1.8
280-350 mg/day
Empiric treatment of Hypomagnesemia
Hypomagnesemia treatment
- Diarrhea may be dose-limiting with oral therapy
- Replace more cautiously in those with renal dysfunction
- Hypokalemia must be corrected concomitantly
- Generally takes 3-5 days to restore levels because up to 50% of a dose is excreted in urine, monitor renal function, adjust replacement if needed
Hypermagnesemia treatment
- IV calsium gluconate- temporarily reverses neuromuscular and cardiavascular effects
- Indicated if [Mg] > 5.0 mEq/L with symptoms or if >8 without
- 1-2 grams repeat if needed
- 0.9% NaCl + furosemide (good renal function) or hemodialysis (renal failure)
- D/C all Mg containing medications (MOM, Maalox)
Summary
Electrolyte disorders need to be?
Understanding the ___ of electrolyte disturbances is?
Knowledge of appropriate electrolyte strategies based on?
Including?
- Identified and treated rapidly
- cause of electrolyte disturbances is important to ensure continued insult is not occurring
- Based on pts serum electrolyte levels
- Including rate of adminitration based on IV access
