IV Fluids (Final) Flashcards
Fluid compartments
- Intracellular
- Extracellular
- Intravascular
- Interstitial
Total body water volume
- 40L
- 60% body weight
Intracellular fluid volume
- 25L
- 40% body weight
- Extracellular fluid volume
- Intravascular?
- Interstitial?
- 15L
- 20% body weight
- Intravascular (plasma)
- 3L
- 20% of Extracellular fluid (ECF)
- Interstitial
- 12L
- 80% of (ECF)
Primary Intracellular ions
- K+
- PO43-
- Non-penetrating anions
- Proteins
- Organic anions
Primary extracellular ions
- Na+
- Cl-
Components of a chemistry panel (CHEM-7, BMP)
- Na
- K
- Cl
- HCO3
- BUN
- Cr
- Glucose
Normal value for Na+
135-145 mEq/L
Normal value for K+
3.5-5 mEq/L
Normal value for Cl-
95-105 mEq/L
Normal value for HCO3-
22-28 mEq/L
Normal value for BUN
7-18 mg/dL
Normal value for Cr
0.6-1.2 mg/dL
Normal value for Glucose
70-115 mg/dL
What is third spacing?
- Shift of fluid from intravascular to interstitial space
- Loss of integrity of vascular endothelium leading to increased permeability
Name some areas of third spacing loss
- Pancreatitis
- Sepsis
- Surgery
- Hypoalbuminemia (Cirrhosis, etc)
What are the goals of giving IV fluids?
- Replacement/Resuscitation
- Maintenance
- Electrolyte balance
Questions to consider before beginning IV fluids
- For replacement, how much extra volume is needed?
- How can we assess volume status?
- What are the sources of volume loss?
- What does it take to maintain normal fluid balance?
Common sites/causes of fluid and electrolyte loss
- Renal
- GI
- N/V
- NG tube
- Fistula
- Respiratory
- Skin
- Especially burns
- Hemorrhage
- Third-space losses
Daily causes for water loss
- Urine
- At least 0.5 l/day
- Stool
- 200 mL/day
- Insensible (skin and respiratory)
- 400-500 mL/day
- Endogenous metabolism
- 250-350 mL/day
Daily water requirements? How much for maintenance?
- Total
- 1400 mL/day
- Maintenance
- Minimum 60 mL/hr
Causes for insensible fluid loss
- Increased respiratory rate
- Changes in metabolic state
- Body temperature
Daily Na+ requirement
75-175 mEq Na+/day
Daily K+ requirement
20-60 mEq K+/day
Daily carbohydrate requirements? What does achieving this do?
- 100-150 g/day dextrose
- Reduce protein catabolism and prevent starvation ketoacidosis
D5 ½ NS with 20 mEq/L KCL running at 75 mL/hr maintenance will result in what after one day?
- 1.8 L of solution
- 36 mEq K+ (need 20-60 per day)
- 139 mEq Na+ (need 75-175 per day)
- 90 g dextrose (need 100-150 g/day)
Covers nearly all of the needs of the patient
How to assess volume status
- Clinical assessment
- Daily Weights
- Intake and Output
- Serum Creatinine
Signs of hypervolemia
- AMS
- Increased hepato-jugular reflux
- Increased JVP
- Increased body weight
- Increased fluid balance
- Increased cumulative fluid balance
- Altered capillary refill
- Pitting edema
- 2nd, 3rd space fluid sequestration
- Orthopnea
Signs of hypovolemia
- Hypotension
- Tachycardia
- Oliguria
- Decreased skin turgor
- Dry mucous membranes
Examples of crystalloid fluids
- Normal saline (NS)
- Lactated Ringer’s (LR)
Example of colloid fluid?
Albumin
Composition of normal saline and risks associated with it
- 154 mEq/L Na+ (140 in plasma)
- 154 mEq/L Cl- (103 in plasma)
- Can lead to hyperchloremic metabolic acidosis (due to high Cl- content)
- Can cause Chloride-mediated renal vasoconstriction
A 2018 study of 15,802 critically ill adults given normal saline or a balanced crystalloid (LR or Plasmalyte) found?
- Giving a balanced crystalloid instead of normal saline resulted in:
- Decreased death from any cause
- Decreased new renal replacement therapy
- Decreased persistent renal dysfunction
Composition of LR compared to plasma
- Na
- LR: 130 mEq/L
- Plasma: 140 mEq/L
- Cl
- LR: 109
- Plasma: 103
- K
- LR: 4
- Plasma: 4
- Ca
- LR: 3
- Plasma: 4
- Mg
- LR: 0
- Plasma: 2
- Osm
- LR: 273 mOsm/L
- Plasma: 290 mOsm/L
Problems with LR
- Blood samples from IV’s running LR can give spuriously high serum lactate measurements
- Ionized Ca in LR can bind to citrated anticoagulant in pRBC’s and cause clots
- 4 mEq/L of K
- Can cause hyperkalemia
- USe caution in Pts with renal insufficiency
Describe colloid fluids such as albumin
- High molecular weight solutions; increase plasma oncotic pressure
- Stay in intravascular space longer than crystalloid fluids
- Albumin has an intravascular half-life of 16 hours
- NS or LR have intravascular half-lives of 30-60 minutes
- Describe the following dextrose containing solutions
- D5W
- D5NS
- D10LR
- D5W
- 50g dextrose in 1L free water (5% dextrose)
- D5NS
- 50g dextrose in 1L NS
- D10LR
- 100g dextrose in 1L LR
Describe the protein-sparing effect of dextrose containing solutions
- Enough non-protein calories to help prevent endogenous protein catabolism
- Not complete nutrition
- Tube feeds/TPN better
- Dextrose containing fluids can be used to treat ongoing hypoglycemia
Main uses of D5W
- Treatment of hypernatremia
- Slowing down correction of hyponatremia
Goals of giving maintenance fluid
- Maintain homeostasis in euvolemic patients who cannot accomplish this with oral intake
- Examples of common rates of maintenance fluid
- D5 ½ NS with 20 mEq/L of K at 75 mL/hr
- NS at 75 mL/hr (less hypoNa risk) with PRN K repletion
- Decrease to 50 mL/hr in Pts with CHF, CKD, etc.
- Many healthier Pts can tolerate higher rates (e.g. 100-125 mL/hr)
- Be sure to frequently reassess volume status
What is the risk of giving maintenance fluids at too high a rate ( > 50 mL/hr) in Pts with fluid balance disorders such as CHF or CKD
Risk of flash pulmonary edema
Goals of fluid replacement (not mantinance)
- Maintain hemodynamic stability
- Replenish intravascular volume
- Fluid Boluses
- 1 L
- 500 mL
- 250 mL
- Special situations
- Reassessment
Which patients need aggressive IV fluid treatment?
- Sepsis
- Acute pancreatitis
- DKA/Hyperosmolar hyperglycemic syndrome (HHS)
Replacement fluid guide for Spesis
- Initial crystalloid bolus of 30 mL/kg
- More fluid guided by serum lactate and hypotension
Replacement fluid guide for Acute Pancreatitis
-
LR
- Initial fluid bolus: 20 mL/kg over 30 minutes, followed by 3 mL/kg/hr for 8-12 hours
Replacement fluid guide for DKA/HHS
- 15-20 mL/kg/hr for first 2 hours
- Approx. 1L/hr
- 250-500 mL/hr next few hours
- Then reduce to 150 mL/hr
What should you keep in mind about complications of giving replacement fluids?
- Risk of aggressive replacement is acute (flash) pulmonary edema
- In Pts with CHF if boluses are needed for hypotension
- Use 250 mL at most and reassess
Guidelines for potassium repletion
- Serum K 3.0-3.4 mEq/L (mild)
- Anticipate 10 mEq administration to increase serum K by 0.1 mEq/L
- Serum K < 3.0 mEq/L
- Requires more aggressive repletion
- Can do PO and IV
- Recheck more than daily
- Requires more aggressive repletion
- Whole-body K deficit often more severe than serum K would suggest
In cases where a Pt has low potassium, what else should you check?
- Hypomagnesemia
- Renal potassium wasting
- Hypokalemia will not correct in the presence of hypomagnesemia
Mg level is not part of BMP, need to order separate Mg level test
Pearls of IV potassium
- Risk for phlebitis
- Painful
- Limit 10 mEq per 2 hours through peripheral IV
- Central access for faster repletion
Guide to treatment for low Mg
- Need to order serum Mg separately from BMP
- Oral replacement does not work well
- Poor GI absorption
- IV Mg
- Give 1-4 g at a time and recheck
In Pts with cardiac disease, what are the goal serum K and Mg levels?
- Serum K
- > 4.0 mEq/L
- Serum Mg
- > 2.0 mEq/L
Quick tips for management of Phosphorus levels
- Need to order serum Phos separately from BMP
- K-Phos neutral (Phos-Nak) tablets
- 1.1 mEq K per tab
- K-Phos IV
- 22 mEq K per 15 mmol
- Na-Phos IV
- No K
- Consider hypophosphatemia in malnutrition or refeeding
- Alcoholics
A 38 year old male with PMH of ETOH use disorder presents to the hospital in EtOH withdrawal and severe electrolyte depletion.
On exam his vitals are: HR: 109, RR 18, BP 90/70, Pulse Ox 95%
Gen: ill appearing male, HEENT: Dry CV: Tachy RR
Labs: Na: 131, K: 3.0
What do you want to do?
- A. Give him a beer, it will help his withdrawal
- B. Start maintenance fluids with D5W at 75 ml/hr and Replete his potassium with 40 mEq
- C. Start maintenance fluids with NS 50 ml/hr and replete K with 40 mEq
- D. Give NS bolus 1000ml and replete K with 60 mEq
- D. Give NS bolus 1000ml and replete K with 60 mEq
Bolus will help with low BP
A 38 year old male with PMH of ETOH use disorder presents to the hospital in EtOH withdrawal and severe electrolyte depletion.
On exam his vitals are: HR: 109, RR 18, BP 90/70, Pulse Ox 95%
Gen: ill appearing male, HEENT: Dry CV: Tachy RR
Labs: Na: 131, K: 3.0
You give a NS bolus 1000ml and replete K with 60 mEq. However, now he develops Severe Epigastric Pain that radiates to the back … What should you do?
- A. Nothing continue to treat his EtOH withdrawal
- B. Order CBC, LFTs, and Lipase
- C. Start IV PPI and order CBC, LFTs, and Lipase
- D. Continue IVF, start IV pain meds, and continue to monitor
- B. Order CBC, LFTs, and Lipase
A 38 year old male with PMH of ETOH use disorder presents to the hospital in EtOH withdrawal and severe electrolyte depletion.
On exam his vitals are: HR: 109, RR 18, BP 90/70, Pulse Ox 95%
Gen: ill appearing male, HEENT: Dry CV: Tachy RR
Labs: Na: 131, K: 3.0
You give a NS bolus 1000ml and replete K with 60 mEq. He develops Severe Epigastric Pain that radiates to the back so you order a CBC, LFTs, and Lipase.
His Lipase comes back 3x the upper limit of normal, his Bili comes back elevated, Hgb is normal
What should you do now?
- A. Start IVF- NS 75 ml/hr, start IV pain control, obtain RUQ U/s
- B. Start IVF- LR 150ml/hr, start IV pain control, Obtain RUQ U/S
- C. Start IVF- LR 150ml/hr, start IV pain control, Obtain CT Abd
- D. Start IVF- D5W 150ml/hr, start IV pain control, Obtain CT Abd
- B. Start IVF- LR 150ml/hr, start IV pain control, Obtain RUQ U/S
Pearls of acute pancreatitis (this is how she recommends breaking down diseases to study them for the PANCE)
- Etiology: Most common EtOH vs. Gallstones
- Diagnostics: Presence of two of the following:
- Acute epigastric pain radiating to back
- Lipase 3 times the upper normal limit
- Characteristics of acute pancreatitis on Imaging (CT/MRI/US)
- Fluid of choice: LR
- Treatment: IVF, NPO, Pain Control