basics of fluid therapy zsolt molnár 2009. physiology
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Basics of fluid therapy Zsolt Molnár
2009
Physiology
The debt…
• DO2= (SV•P) • (Hb•1.39•SaO2+0.003•PaO2) ~ 1000ml/m (SaO2=100%)
• VO2 = CO • (CaO2 - CvO2) ~ 250 ml/m (ScvO2~70-75%)
CO CaO2
The debt…
• DO2= (SV•P) • (Hb•1.39•SaO2+0.003•PaO2) ~ 1000ml/m (SaO2=100%)
• VO2 = CO • (CaO2 - CvO2) ~ 250 ml/m (ScvO2~70-75%)• A hypovolémiás, vérző beteg:
• Sokk = VO2>DO2
VO2DO2
CO CaO2
Fluid therapy
Infusion fluids and their distribution
TBW ~ 40L
I.st.~15L I.v.~5L0.6xTBV ~ 20L
I. c. E.c.
Coll
NaCl
5%D1/83/84/8
1/43/4
1/1
Fluid compartments
Main considerations
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• Distribution:• Water (5%D) in the TBW (1/8)
• Na+ in the e.c. (1/4)
• Colloid in the i.v (1/1)
• Therefore:• 1 L blood loss can be replaced with…
• …4 L isotonic saline, or…
• …1 L colloid.
Infusions
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Signs of hypovolaemia?
• Pulse - MAP
• Capillary refill
• Hourly urine output
• Core – peripheral temperature differance
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• Moderate bleeding
• Sensitivity: 20-30 %McGee S, et al. JAMA 1999; 282: 720
Clinical signs of hypovolaemia
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Start with a Subjective Assessment of Skin Temperature to Identify Hypoperfusion in Intensive Care Unit Patients
Kaplan LJ, et al. J Trauma 2001; 50: 620-7
Cold hands = Hypoperfusion: 39% pos. pred. Cold hand + low HCO3 = Hypoperfusion: 98% pos. pred.
How shall we give it?
Peripheral lines
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• Features• 24 ….14 G
• Color coded» Pink: 20 G
» Green: 18G
» White: 17G
» Grey: 16G
» Orange: 14G
• Simple, fast
• Little complications
Hagen-Poiseuille’s law
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• Importance:• Intravenous fluid replacement
• Airways
• Effective: short &thick
10
4
8
πpp
l
RI
p 0 p 1
l
Rr r+ d r r+ dr r
v v+ dv
Peripheral lines
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• Int. jugular vein– Close to the skin, „far” from the lungs
– Carotid artery can be compressed
• Subclavian vein– Close to the lungs, far from the skin
– Subcl. artery cannot be compressed
• Femoral vein– Far fromthe skin, close to the groin
– Fem. artery can be compressed
Central lines
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• Pain– Use local anaesthesia all the time
• Arterial puncture– Inc ase of clotting disorder – use femoral, jugular approach
• Pneumothorax– Subclavian > int. jugular
• Catheter infection– Femoral > int. jugular > subclavian
– Prevention: regular (7-10 days) change
CVC: complication
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CVC catheter set
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Seldinger’s technique
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US guided puncture
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CVC in the int. jugular vein
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CVC in the subclavian vein
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Position of the tip of the catheter
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Christalloid or colloid?
Mortality
Choi PT et al. Crit Care Med 1999; 27: 200
SAFE
Finfer S et al. SAFE study. N Eng J Med 2004; 350: 2247
SAFE
Finfer S et al. SAFE study. N Eng J Med 2004; 350: 2247
Instead of summary
• „Early Goal-Directed Therapy” (EGDT)Rivers E et al. N Engl J Med 2001; 345: 1368
• Septic patients treated on A&E for 6 hours:– Control group (n=133):
• O2
• CVP: 8-12 mmHg• MAP >65 mmHg
– EGDT group (n=130):• Same as above• ScvO2 > 70% •More fluid, blood
•More dobutamine
Mortality: 46 vs. 30% (p=0.009)
Monitorozás, terápiás végpontok
• Otto Frank, Ernest Starling – 1914: „Law of the heart”– „The mechanical energy set free in the passage from the resting to the
active state is a function of the length of the fiber„
– „Within physiological limits, the force of contraction is directly proportional to the initial length of the muscle fiber”
• Most common reasons of HF:– Reduced circulating volume
– Reduced pump function
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EDV
SV
„End point” of resusscitation
Haemodinamics
Starling EH. The Linacre Lecture on the Law of the Heart. London; 1918Starling EH. J R Army Med Corps. 1920; 34: 258-262
Summary
• Basic physiological knowledge • Read the label!• Fluid therapy is also revolving around: O2
Diagnosis can wait but cells can’t!