IM Fluids and Electrolytes

Fluids

Total Body Water

• Percentages:
  • Average adult: 60%
    
  • Women/Elderly: <50%
    
  • Young children: >70%
    
  • Obesity: <60%
• Location:
  • ICF: 66%
    
  • ECF: 33%
    
  • Insterstitial: 75%
    
  • Plasma: 25%

Plasma

• Components:
  • 140 mEq Na, 98 mEq Cl, 0 mEq lactate, 5 mEq K+, 23 mEq gluconate, pH: 7.4

Fluid Loss

• Body’s response to fluid loss:
  • Na+ & H2O retention (Renin > Angiotensin), H20 retention via ADH, vasoconstriction via sympathetic/angiotensin, decreased urine output, tachycardia (early) & hypotension (late)
• Location of fluid loss:
  • GI: diarrhea, drains, ostomies, or pathologies: BGS 123 (Bile 1L, Gastric 2L, Small bowel 3L)
    
  • Genitourinary: diuretics, meds, diabetes
    
  • Insensible losses: burns, evaporation-sweat, respiratory
    
  • Intake: NPO, dehydration, polydipsia, dysphagia/mechanical

Fluids

• Isotonic Fluid:
  • Contains about the same osmotically active particles as extracellular fluids, so fluid doesn’t shift but expands intravascular volume (stays in the vessel); NS, LR
• Hypotonic Fluid:
  • Contains less solute than extracellular fluid, so they move from the bloodstream into the cell (out of the vessel); 1/2 NS
• Hypertonic Fluid:
  • Contains more solute than extracellular fluid, so fluid is pulled into the bloodstream from the cell (enters vessel); 3% hypertonic saline, D5NS, Colloids

Fluid Replacements

• Types:
  • Normal Saline (0.9% NaCl):
    • 154 mEq Na+, 154 mEq Cl, 0 mEq lactate, pH: 5.5
  • D5NS:
    • Hypertonic, but isotonic in the vascular compartment
  • D51/2NS:
    • Hypertonic, but isotonic in the vascular compartment & can be used for maintenance fluids
  • D5W:
    • Labeled hypotonic, but isotonic in the vascular compartment (free water)
  • Lactated Ringers (LR):
    • 130 mEq Na+, 109 mEq Cl, 4 mEq K+, 28 mEq lactate, 3 mEq Ca, pH: 6.75
• Rate of Maintenance Fluid:
  • 60 kg adult: 95-100 ml/hr
  • 90 kg adult: 120 mL/hr
  • 108 kg adult: 136 mL/hr
  • MD Calculator
• Common fluid bolus dosing:
  • Adult: 1-2 L isotonic crystalloids (NS/LR)
    
  • Adult sepsis: 30 cc/kg within the first 3 hours
    
  • Peds: 20 cc/kg
• Common peds maintenance fluid:
  • 1/4 NS D5
  • Use Holiday-Segar method formula
• Common adult maintenance fluid:
  • 1/2 NS D5
• Free water deficit:
  • Formula: TBW x actual serum Na+ – Ideal serum Na+/Ideal serum Na+
     
  • TBW = % body water (.6 for males and .5 for females) x kg
     
  • Replace with PO/enterally (PEG, NG), D5W or D51/2 NS
• Replenish Electrolytes:
  • Hypotonic solutions

Nutrition

• Treatment:
  • 20% and 50% dextrose solutions are commonly used in CPN solutions

Dehydration

• Treatment:
  • 2.5 and 5% dextrose

Burns

• Burn maintenance fluid:
  • Parkland Formula; 4 mL x BSA x kg
    
  • 50% given in the first 8 hours
    
  • 50% given over the next 16

Electrolytes

Normal Blood Gas Values

• pH: 7.35-7.45
  
• H+: 45-35
  
• PCO2: 35-45
  
• HCO3-: 22-26

Metabolic Acidosis

Metabolic Alkalosis

• Treatment:
  • Likely responsive to IVFs, volume & need Cl (Normal Saline)

Hyponatremia

• Etiology:
  • MC cause of electrolyte abnormality of hospitalized patients
• Presentation:
  • Headache, fatigue, cramps, N/V, confusion, seizures, coma

Hypernatremia

• Presentation:
  • Thirst, weakness, nausea
• Treatment:
  • Acute: intravenous 5% dextrose 
  • Chronic: half-normal saline (0.45% sodium chloride) if unable to tolerate oral water.

Hyperkalemia

• Causes:
  • pseudohyperkalemia (hemolysis of blood sample)
• Work-Up:
  • Serum chemistries (CMP)
  • evaluate Mg (Mg depletion impedes K+ repletion)
  • EKG (most rhythm disturbances occur in patients with underlying heart disease),
    • Mild (5.5-6.5): Peaked T waves, prolonged PR
      
    • Moderate (6.5-8.0): Loss of P wave, prolonged QRS, ST elevation, ectopic beats & escape rhythms
      
    • Severe (>8.0): Progressive widening of QRS, sine wave, v-fib, asystole, axis deviations, bundle branch blocks, fascicular blocks
      
       
• Treatment:
  • Phase 1:
    • Membrane stabilization:
      • Calcium gluconate (10%), hypertonic (3%) NS (not really used),
    • Monitor rhythm strip,
    • check glucose at 30 min, K+, and EKG at 30-60 minutes
  • Phase 2:
    • Temporize the K/Shift the K with shifters:
      • insulin (short-acting), albuterol,
    • monitor rhythm strip, glucose at 30 minutes, K and EKG at 30-60 minutes
  • Phase 3:
    • Excreters (pee & poop it out):
      • Furosemide,
      • Sodium bicarbonate,
      • sodium polystyrene sulfonate.
      • Dialysis is definitive

Hypokalemia

• Causes:
  • Abnormal GI and renal losses (diuretics, laxatives, diarrhea, dialysis),
  • transcellular shifts (medications, DTs, thyrotoxicosis, myocardial ischemia),
  • inadequate intake (dementia, starvation, TPN, anorexia)

• Work-up:
  • CMP
  • Mg (not on a CMP, need to order separately) 
  • EKG:
    • decreased T-wave amplitude, ST-interval depression, T-wave flattening or inversions, PR-interval prolongation, and U waves
• Treatment:
  • Replacement:
    • PO with 40 mEq q4 hours (6 doses)
       
    • plus Mg (not on a CMP, need to order separately) – Must be corrected with K+
       
       
  • Critical Hypokalemia with arrhythmia:
    • Dialysis
• Note:
  • 10 mEq KCL is needed to increase K by 0.05-0.1 where potassium is >3
  • 15 mEq KCL is needed to increase K by 0.1 where potassium is 2.5-3
  • 20 mEq KCL is needed to increase K by 0.1 where potassium is 2-2.5 or less

Hypermagnesemia

• Presentation:
  • Hyporeflexia, weakness, EKG similar to hyperkalemia; peaked T waves, bradycardia, asystole
• Causes:
  • TPN, excessive supplementation, renal failure, rhabdomyolysis, lithium toxicity, metastatic disease
• Treatment:
  • IV calcium gluconate,
  • insulin & glucose,
  • furosemide

Hypomagnesemia

• Presentation:
  • Chvostek/Trousseau, tetany, delirium, weakness, Torsades de Pointes on EKG
• Causes:
  • TPN, suctioning, meds, renal failure, vomiting, diarrhea
• Treatment:
  • acute: IV bolus Mag sulfate: 1-2g bolus,
  • chronic: banana bag (3g) or PO.
  • Correct associated hypokalemia

Hypocalcemia

• Presentation:
  • Chvostek, Trousseau, tetany, seizures, myocardial dysfunction
• Causes:
  • Decreased PTH or vitamin D deficiency, hypoalbuminemia, acid/base disturbances, sepsis, hypomagnesemia
• Treatment:
  • Correct underlying metabolic abnormalities,
  • vitamin D supplementation,
  • PO/IV calcium gluconate,
  • correct hypomagnesemia
• Calcium affected by albumin:
  • The serum total calcium concentration falls approximately 0.8 mg/dl for every 1 g/dl reduction in the serum albumin concentration
  • Treat with IV in 5% or 25% for volume expansion after crystalloids in CT surgery, after large-volume paracentesis, hepatorenal syndrome, & plasmapheresis

Hypercalcemia

• Presentation:
  • Constipation, stones, moans, groans, psychiatric overtones, renal failure
• Causes:
  • Hyperparathyroidism & cancer
• Treatment:
  • IV fluids,
  • treat underlying causes,
  • diuretics,
  • calcitonin IM/IV,
  • steroids,
  • bisphosphonates,
  • dialysis,
  • Denosumab SC

Hypoglycemia

• Treatment:
  • 50% Dextrose in water

Hyperglycemia

• Work-up:
  • CMP
    • Check Na – It will appear falsely low
• Treatment:
  • Na correction – Add 1.6 Na for every 100 glucose above 1st 100

Diabetic Ketoacidosis

• Presentation:
  • Abdominal pain, vomiting, confusion, coma, polyuria, dehydration, Kussmaul breathing

Hyperglycaemic hyperosmolar non-ketotic coma (HONK)

• Etiology:
  • A complication of DM2; hyperglycemia without ketosis with sx of confusion, coma, thirst, poluria, dry mouth, & hallucinations
• Treatment:
  • ABCs, vigorous IV fluid replacement with isotonic crystalloids, IV insulin, correction of hypokalemia/electrolytes, treat the underlying illness

Transfusion

Transfusion Products

• Types:
  • Whole Blood:
    • Not common except for acute hemorrhage,
    • replaces blood volume & all products
  • PRBCs:
    • Most common blood product
    • increases O2 carrying capacity,
    • 1 unit increases Hct 2-3% mixed with NS,
    • no platelets or clotting factors.
       
  • Platelets:
    • Replace platelets in bleeding disorders or platelet deficiency,
    • 1 unit increases platelets by 5,000 plt/mcL
  • FFP:
    • Plasma liquid component of blood,
    • expands volume & has clotting factors,
    • no RBC/WBC/plts,
    • 1 FFP increases CF by 2-3%
  • Albumin/plasma protein fraction:
    • Expands volumes, plasma proteins
  • Clotting factors & Cryoprecipitate:
    • Certain factors (vWF), contains fibrinogen

Blood Transfusion

• Indications:
  • Severe symptoms d/t anemia,
  • stability/instability d/t ongoing bleeding,
  • Seven (Hgb),
  • Single-unit transfusion preferred
• Type and Screen:
  • ABO & Rh of patient,
  • blood not held but could be mobilized quickly (order if you may need it)
• Type and Cross:
  • ABO & Rh and will check the patient’s blood with the sample for reactivity for each unit ordered (must know you are giving the blood).
  • Fully cross-matched takes 45 minutes,
  • emergency crossmatch: 15 minutes
• PRBC’s:
  • One unit = increase the Hct 3-4% and Hgb 1 g/dL
• PRBC transfusion guidelines:
  • Hgb <6: recommended
  • Hgb 6-7: generally indicated
  • Hgb 7-8: may be indicated in symptomatic w/ ongoing blood loss, critically ill, or surgical pts.
  • Hgb 8-10: not indicated, but considered for ongoing bleeding, the risk for bleeding, heme/onc pt w/ thrombocytopenia or in ACS w/ ischemia
  • Hgb >10: generally not indicated
• Massive Transfusion in trauma:
  • Transfusion in critically ill, hemodynamically unstable pt,
  • can’t be guided by Hgb alone (can’t wait for labs).
  • Usually given in 1:1:1 ratio; RBCs: Plasma: Plts

Transfusion-associated circulatory overload (TACO) 

• Treatment:
  • O2, slow transfusion, maintain airway, diuresis to reduce volume, consider ACS (NSTEMI and STEMI)

Transfusion-related acute lung injury (TRALI)

• Treatment:
  • O2, maintain airway, mechanical ventilation, IV fluids to treat hypotension, consider ARDS

Disseminated intravascular coagulation (DIC)

• MC in conditions with:
  • Leukemias, pancreatic cancer, prostate, breast, & ovarian cancers
• Work-Up:
  • Low platelets, prolonged PT/INR & aPTT, increased D-Dimer, elevated BUN/Creatinine, peripheral smear
• Treatment:
  • ABCs, IV NS, FFP/Platelets, PRBCs,
  • treat the underlying cause & supportive care