Transcript IV Fluids - Department of Medicine

Mini Lecture: IV Fluids
William Graham, PGY2
January 2014
Department of Medicine
UC Irvine Medical Center
Objectives
• Understand daily fluid and electrolyte
requirements for an average adult
• Understand the major components of
replacement fluid
• Maintenance vs. Resuscitation
• Complications of fluid therapy
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Water Input and Output of the “Normal” Adult
• Minimal Obligatory Daily Water input:
– Ingested water: 500mL
– Water content in food: 800mL
– Water from oxidation : 300mL
TOTAL: 1600mL
• Minimal Obligatory Daily water output:
Urine: 500mL
Skin: 500mL
Respiratory tract: 400mL
Stool: 200mL
TOTAL: 1600mL
→ Average adult input/output is 30-35mL/kg/day (2.4L/day)
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Contents of IV Fluid Preparations
Na
(mEq/L)
K
(mEq/L)
Cl
(mEq/L)
HCO3
(mEq/L)
D5W
½ NS
77
77
D51/2NS
77
77
NS
154
154
D5NS
154
154
Ringers
Lactate (RL)
130
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4
109
Dextrose
(gm/L)
mOsm/L
50
278
143
50
350
286
28
50
564
50
272
Daily Electrolyte Requirements
• - Sodium: 100-250meq (western diet)
– mostly excreted in urine
• - Potassium: 50-100meq
– mostly excreted in urine, 5% in feces
• - Chloride: 60-150meq
– Example: 1/2NS @ 100cc/hr provides ~180mEq of sodium and chloride/day!
- this is why NS should not be used for maintenance fluid in patients
with normal renal function- risk of hyperchloremic metabolic acidosis
• - Bicarb: 1 meq/kg/day
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Case Vignette
58 y/o male with h/o HTN, dyslipidemia, admitted for cough and
atypical chest pain. Found to have abnormal CXR and CT Thorax
concerning for malignancy . Kept NPO overnight for possible
bronchoscopy with biopsy in the morning. He is placed on NS @
75cc/hr.
1. Was the right solution picked?
2. Is the rate correct?
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Maintenance Therapy
Purpose: Replace ongoing losses of water and electrolytes under
normal physiological conditions
- Used when the patient is not expected to eat or drink normally
for prolonged period of time
- In general, patients who are afebrile, not eating, not physically
active require less that 1 L of free water daily
- Patient’s with ESRD or edematous states (ex. cirrhosis, heart
failure) require less maintenance due to decreased output and/or
altered fluid distribution
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Maintenance Therapy
3 approaches to determine the appropriate rate:
1) Calculate maintenance based on average requirement of 35cc/kg/day
2) “4/2/1” rule
4 ml/kg/hr for the first 10 kg (0-10kg)
2 ml/kg/hr for the next 10kg (11-20kg)
1 ml/kg/hr for remaining weight (21 kg and up)
3) Weight in kg + 40
Vignette: Pt weight 85kg.
*
–
85kg x 35cc/kg/24hr= 3L/24 hr= 125cc/hr
–
40 + 20 + 65 = 125cc/hr
–
85 + 40 = 125cc/hr
Maintenance Therapy
What type of fluid for maintenance?
- D51/2NS + 20 mEq KCl provides:
a) ~180 mEq/day sodium and chloride (100-250 sodium and 60-150 chloride
needed/day)
b) ~50 mEq/day potassium (50-100 mEq needed/day)
- avoid dextrose in patients with uncontrolled DM or hypokalemia
- not much data to support addition of D5, however can be added to prevent
muscle catabolism
- Therefore, 1/2NS or D51/2NS + 20 mEq KCL would be appropriate choices.
- adjust maintenance fluids based on serum sodium concentration (ex. Change
from 1/2NS to NS or D5NS if hyponatremia develops)
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Clinical Vignette
86y/o female admitted with nausea and vomiting and c/o
rectal bleeding. She has a history of recent admission for CHF
exacerbation. Weight is 45kg. SBP 80’s in the ED. She is
started on IV pantoprazole.
1. What is your initial choice of fluids?
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Fluid Resuscitation
Purpose: Correct existing abnormalities in volume status or
serum electrolytes
Objective parameters used to assess volume deficit:
• Blood pressure
• Jugular venous pressure
• Urine sodium concentration
• Urine output
• Pre and post deficit body weight
*
Rate of Repletion
Severe volume depletion or hypovolemic shock?
-> Rapid infusion of 1-2L isotonic saline (NS), then reassess parameters
- use Lactated Ringers if concern for re-expansion acidosis (ex. acute
pancreatitis)
Mild to moderate hypovolemia?
1) Estimate fluid losses:
– Recall: Average output 2.4L/day for 70kg patient
– estimate additional losses such as GI (diarrhea, vomiting) and high fever
-> add 100ml/day for each degree of temp > 37C
2) Choose rate 50-100mL/h greater than estimated losses
3) Select fluid based on type of fluid that has been lost and any co-existing
electrolyte disorders
*
Clinical Vignette
86y/o female admitted with nausea and vomiting and c/o rectal
bleeding. She has a history of recent admission for CHF
exacerbation. Weight is 45kg. SBP 80’s in the ED. She is started on
IV pantoprazole.
1. What is your initial choice of fluids?
2. She is kept NPO for EGD and colonoscopy the next
morning. After receiving 2u PRBC and normal saline you
decide to start maintenance fluids. What rate and type of fluid
do you choose?
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Complications of IVF
The team decides to put her on D51/2NS @ 125cc/hr. Her repeat
serum sodium level is 130 the next morning and she is
complaining of some SOB. She is thought to have an infiltrate on
CXR and started on IV Zosyn and Vancomycin for hospital acquired
pneumonia.
3. What could be contributing to the hyponatremia?
4. What is likely contributing to the SOB?
*
Where is my bolus going?
1L D5W distributed into Total Body Water
Free water
content
ICF
ECF
Interstitial
Intravascular
Interstitial
Intravascular
D5W
1000cc
660cc
340cc
226cc
114cc (11%)
226cc
114cc!!
½ NS
500cc
500cc
500
330cc
+ 55cc from
free water content
170cc + 55cc
=225cc (22%)
NS
0
0
1000cc
660cc
330cc (33%)
Normal saline has no free water and is confined to ECF space;
this is why it is the preferred IVF for resuscitation!
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Summary
• Treat IV fluids as a prescription just like any other medication,
with consideration of renal function and clinical picture
• Determine if patient needs maintenance or resuscitation
• Choose fluid type based on co-existing electrolyte disturbances
• Don’t forget about additional IV medications patient is
receiving
• Choose rate of fluid administration based on weight and
minimal daily requirements
• Avoid fluids in patients with ECF volume excess
• Assess DAILY whether the patient continues to require IVF
*