Perioperative Fluid

Perioperative Fluid

Management
Fred Rotenberg, MD
January 10, 2007

Goals of Fluid Administration

• O2 delivery / blood flow - perfusion
• Maintain electrolyte composition,
• Glycemia,
• Body temperature

O2 Delivery

• DO2~ Q x CaO2
• CaO2 ~ SaO2, CO, Hgb
• CO ~ SV x HR
• SV ~ preload, afterload, contractility

Maximizing CO

• Slope of curve is EF
• “Good” ventricles are preload dependent
• “Poor” ventricles are afterload dependent – (not preload dependent)

For Low SV / CO

• Good LV function -> give fluid
• Poor LV function -> Inotropes
• Vasodilators
• Diuretics

How much to give and when to give it

• IT DEPENDS-
• Type of patient
• Type of surgery
• Amount of trauma
• Acute injury vs. elective
• Anesthetic, positioning
• Who you listen to

 
“Classic” fluid management

• Deficits
• Maintenance
• 3 rd Space
• Blood loss

Deficits

• Estimate
• Preop NPO (hourly maintenance x duration)
• Preop bowel preparation (1-1.5L)
• Preop blood loss (trauma) or fluid loss (burns)

Typically replaced over first 2-4 hours
Maintenance

• (4-2-1 rule)
• 4 ml/kg/hr for first 10 kg of body weight
• 2 ml/kg/hr for 2nd 10 kg of body weight
• 1 ml/kg/hr for each kg of body weight above 20 kg
• Based on water loss from burning calories
• from Holliday and Segar

Replace fluid losses

• “Third space” 2-10 ml/kg/hr
• Blood losses:
• 3 to 1 ratio of crystalloid to EBL
• 1 to 1 for colloid or blood
• (or hypertonic saline)

Surgical Trauma: Third Spacing

• Capillary and Endothelial injury; leak
• Sequestration of fluid into tissues
• i.e. TRAUMA causes FLUID Retention

Surgical Trauma: Third Spacing

Capillary and Endothelial injury; leak
Sequestration of fluid into tissues
i.e. TRAUMA causes FLUID Retention
Creation of nonfunctional component of ISF
Return of fluid from this ‘third space’

Creation of nonfunctional component of ISF

• Return of fluid from this ‘third space’ 1-4 days after surgery

Surgical Trauma – 3 rd space

• Shires: Annals of Surgery 1961
• Minor (< 200cc EBL) vs Major (>200cc EBL)
• No fluids administered for at least 2 hours
• Measured Functional Extracellular Fluid
• Minor Surgery had minimal changes in ECF; 1.4%
• Major Surgery had 0-28% changes in ECF
• Conclusions
• Change in ECF secondary to redistribution
• Change not related to blood loss
• Change correlate with amount of trauma to tissues
• Retractors and manipulation
• Shires: Annals of Surgery 1961
• Minor (< 200cc EBL) vs Major (>200cc EBL)
• No fluids administered for at least 2 hours
• Measured Functional Extracellular Fluid
• Minor Surgery had minimal changes in ECF; 1.4%
• Major Surgery had 0-28% changes in ECF
• Conclusions
• Change in ECF secondary to redistribution
• Change not related to blood loss
• Change correlate with amount of trauma to tissues
• Retractors and manipulation

Distribution of Fluid

Healthy outpatients – minor procedure
   1 vs 2 liters of fluid

   Decrease thirst, dizziness, drowsiness pain and nausea

   Reduce time til discharge

    May improve respiratory function post operatively 

Outpatient ASA I-II for Lap CCY

• More generous fluids (15 vs 40 ml/kg for the case)
• Improved post op pulmonary fxn
• Improved exercise tolerance
• Improve nausea, “well being”, dizziness, drowsiness, fatigue, balance
• Holte et al. Ann Surg 2004

Risks of Excess Fluids

• Interstitial edema
• Impaired cellular metabolism
• Poor wound healing
• Decreased pulmonary compliance
• Heart failure – overload
• Delayed return of bowel function
• Hemodilution

Postoperative Weight Gain

• Lowell et al CCM 1990
• 48 patients admitted to SICU
• 40% of patients had > 10% weight gain
• Weight gain related to:
• Mortality
• RBC transfusion
• FFP transfusion
• Mechanical Ventilation

When matched to controls, fluid administration was significant variable

• Restricted = 4 ml/kg/hr (e.g. 850ml) vs.
• Liberal = 10 ml/kg bolus + 12 ml/kg/hr (e.g. 3200)
• Earlier bowel function and hospital discharge, less weight gain with restriction
• Nisanevich et al. Anesth 2005

Pulmonary Surgery

• Miller et al: Annals Thoracic Surg 2002
• 115 completion pneumonectomies
• PPE occurred in 15% with Mortality of 43%
• Mortality related to Fluid administration 12 hours 1800 vs 2500
• 24 hours 2300 vs 2800

Hemodilution: Cardiac Effects

• Mangano NEJM 1991, JACC 1991:
• 83/474 cardiac events (17%) noncardiac surgery
• 30/84 CHF (35%)
• 1-3 days postop; vascular patients more frequent
• Speculation: related to greater fluid administration to patients at risk
• Nelson CCM 1993: vascular surgical patients
• Worse outcome with Hct < 28%
• Speculation: Due to hemodilution
• Spahn JTCVS 1993: 19 dogs with acute LAD occlusion
• Ischemia with hemodilution to Hgb 7.5 gm/dl
• Baron Anesth 1987
• Epidural dosing and fluid loading (500 cc) in patients with WMA
• Mangano Circ 1980 and Dehert Anesth 1999
• Impaired contractile response to fluid bolus (500-1500) or leg elevation when compared to Phenylephrine

Hepatic Resection
 Low CVP Technique

• Melendez et al J Am Coll Surg 1998
• Low CVP technique: 496 resections
• IVF 1 cc/kg/hr and boluses as needed
• NTG, dopamine, mannitol as needed
• Urine output > 25 cc/hr
• SBP > 90 mmHg
• CVP < 5 mmHg
• Results
• Reduction in EBL and transfusion
• One patient with renal failure due to aminoglycoside
• Improved visualization of surgical field
• Reduces pressure in hepatic tissues

Hip Replacement

• Sharrock: Br J Anaesth; Reg Anesth
• 987 surgeries
• Spinal/Epidural hypotension (mBP 50-55mmHg)
• Fluid restriction to minimize perioperative CHF
• Epinephrine as needed to maintain BP and CO
• Improved Outcome
• 2 myocardial infarction
• Reduction in EBL and transfusions compared to controls
• 0 renal failures
• 3 deaths (0.4%)

Trauma – “Scoop and Run”

• Bickell: NEJM 1994
• 598 penetrating torso injuries: pre SBP < 90 mmHg
• Immediate (309) vs Delayed (298) fluid resuscitation
• Outcome
• Preop Fluid: 2500cc vs 350cc
• Less periop blood transfused: 2070cc vs 1720cc
• Improved pulmonary function
• Decreased mortality

WHAT’S DIFFERENT BETWEEN OUTPT AND INPT?
      I.E. THE PREOP CONDITION OF THE PT
     THE EXTENT OF TRAUMA (AND 3RD SPACE LOSS)
    THE ABILITY TO HANDLE FLUIDS
    THE ANESTHETIC EFFECTS

Effects of Anesthesia
……transient

• Regional
• Vasodilation - venous pooling
• General
• Myocardial depressants
• Vasodilation
• Reductions in natriuretic hormone
• Increase in Anti-diuretic hormone
• Mechanical Ventilation
• Decrease in venous return
• FLUID ELIMINATION IS GREATER POST-OP
• BUT THE RATE OF ELIMINATION IS NOT RELATED TO AMT OF FLUID ADMINISTERED

 
Isoflurane

• Promotes extravascular fluid accumulation

during crystalloid loading (i.e. 3 rd space loss)

• Not related to mechanical ventilation
• Is this due to increased ADH, ANP?
• Reduces GFR by 30-50%
• Renal blood flow by 40-60%
• Urine output by 65%

Fluids? Drugs? Both?

• Volume status? HX; PE; LABS
• I.E. What is hypovolemia?

- Check neck veins, urine volume and color

• Labile blood pressure suggests hypovolemia
• The “Rotenberg Rule” – when the HR is higher than the systolic BP -> give fluid
• Respiratory variation in BP or pulse ox pleth

Monitors

• Skin color, reperfusion, mucous membranes, weight change
• HR, BP (systolic pressure variation)
• I’s/O’s; Fluid Administration, Urine output, Blood loss
• ETCO2; PaCO2-ETCO2
• CVP, PAP, PCWP, CO, MvO2
• TEE – Doppler CO measurements

Arterial vs Plethysmographic Dynamic Indices for Testing Fluid Administration in Hypotensive Patients

• Only ½ of hypotensive pts increase CO s/p fluid challenge
• BP and plethysmographic variation w/ PPV predicts responsiveness to fluids
• Anes Anal 103:1478 (Dec’06)

Predicting response to fluids

• ?Baseline BP - X
• ? Baseline HR - X
• ? Baseline Filling pressures - X
• Baseline CI !
• ?Respiratory variation of BP or SaO2 pleth
• Response to fluid loading of the above !

Goal directed Therapy
Does it make a difference?
Goal directed fluid therapy

• Hemodynamics / systolic pressure variation
• CVP / PCWP
• Cardiac output / SV
• O2 delivery (CO plus SaO2)
• Fluids plus inotropes -

Timing of fluids

• Preop fluids retained shorter than intra-op fluids
• I.e. Surgical fluids are retained
• Scoop and run vs. early fluid administration

 
Choice of fluids

• Crystalloids
• Colloids
• Blood products
• Whole blood
• PRBC
• FFP
• Platelets

Colloids do not improve outcome

• Meta-analysis showed a 12.3% worsenedmortality with colloids in multiple trauma
• Saline solutions may produce hyperchloremic acidosis

Colloids and Renal Dysfunction

• The dehydrated patient who receives considerable amounts of (hyperoncotic) colloids is especially at risk for developing ARF. It may be advisable to administer colloid in addition to, rather than in lieu of, crystalloids. Boldt & Priebe, A and A 2003

Hypertonic (hyperosmolar) solutions

• Temporarily shifts water from intracellular and interstitial space to intravascular space
• Reduces CSF secretion rate

Limit volume of Hypertonic Saline

• 1 liter of 3% max
• Too much 3% may
• Cause rebound intracranial hypertension
• Cause hyperchloremic acidosis, hypokalemia
• Cause intracellular dehydration
• Hyperchloremia may cause renal vasoconstriction

Clinical Studies of Hypertonic Saline

• Efficacious for hypotensive brain injured pts in transfer to hospital
• Lesser amount of cerebral edema
• May reduce ICP where mannitol has failed
• Improves CO /reduces SVR better than LR
• Promotes diuresis, reduces edema
• Increased serum sodium (to ~150’s) is well tolerated

Clinical Studies of Hypertonic Saline

• 1919 Weed and McGibben – effective in reducing ICP
• 1992 Fisher – decreases ICP following head trauma in kids
• 1997 Wade et al – 2 fold improved survival in adult trauma pts

Summary

• {1} Healthy pts; minimal trauma ->

be generous

• {2} Sicker patients; significant trauma ->

be stingy
In this 2 nd case – goal directed therapy maybe helpful. (Resp variation in sys BP, SaO2 pleth.)

My Recipe

• If you need fluid -
• 2 L of Ringers, then 500 ml of 3% saline
• Then, consider blood products or colloid

 

Metabolic Acidosis

Metabolic Acidosis
A Review by
George B. Buczko MD FRCP(C)

Case Presentation 1

• 54 year old man with fever and abnormal liver function for liver biopsy
• Biopsy “well tolerated” until 3 hours afterwards when he developed abdominal distension , with systolic BP 40 and Hg 4.6

Case Presentation 2

• Vasopressin and bicarbonate infusions and blood transfusion restored BP to 85/40
• The patient was rushed to the OR for exploratory laparotomy

Case Presentation 3

Arterial blood analysis:
pH 6.95, p aO 2 337, p aCO 2 44, TCO 2 10 H +102nM
Na 142, K 6.3, Cl 106 anion gap 26
Albumin 1.2g/dl
Expected anion gap 6 because of low albumin
Anion gap 20 above expected
Lactate 18.3meq/l
Minute ventilation 6.4 liters

Case Presentation 4

• The problem: high H +
• Cerebral enzyme dysfunction
• Cardiac enzyme dysfunction
• Myocardial dysfunction in the face of hemorrhagic shock
• Downward spiral from more than just blood loss

Metabolic Acidosis

• Definition
• Acid-Base physiology
• Anion gap
• Differential diagnosis of metabolic acidosis with high anion gap
• Lactic acidosis
• Oxidative phosphorylation
• Types of Lactic acidosis
• Treatment of Lactic Acidosis

Metabolic Acidosis
(primary fall in serum bicarbonate)

• A condition that causes a primary fall in serum bicarbonate level
• H + + HCO 3 - D H 2CO 3 D H 2O + CO 2

Metabolic Acidosis
(primary fall in serum bicarbonate)

• H + + HCO 3 - D H 2CO 3 D H 2O + CO 2
• According to the above, a fall in HCO 3 - will result from:

1. Addition of H + (shift right: $ in HCO 3 - )
2. Loss of bicarbonate (shift left: Ÿ in H+)

• Increase in H + occurs in both situations
• Metabolic Acidosis
  (primary fall in serum bicarbonate)

Increase in H +:

• Enzyme dysfunction which leads to
• Organ dysfunction

Heart/Brain
Metabolic Acidosis
(primary fall in serum bicarbonate)
Increase in H +:

• H + is accompanied by an anion in order to maintain electrical neutrality
• The anion may be Cl - (HCl administration)
• The anion may be LACTATE, a KETONE, PHOSPHATE, SULPHATE, or an ingested anion

Metabolic Acidosis
(primary fall in serum bicarbonate)
The Anion Gap:

• In the body

cations = anions

• Not all of the anions are measured in routine laboratory analysis
• [Na +] – ([Cl -] + [HCO3 -]) = 12

Metabolic Acidosis
(primary fall in serum bicarbonate)
The Anion Gap:

• The usual unmeasured anions that account for the “gap” are:

Albumin
Phosphates
Sulphates

Metabolic Acidosis
(primary fall in serum bicarbonate)

• The Anion Gap:
• #anion gap in the presence of #[H +] is a marker for the presence of anions that accompany H +but are not routinely measured

Metabolic Acidosis
(primary fall in serum bicarbonate)
High Anion Gap Acidosis:
Type Anion:

• Lactic lactate
• Diabetic ketones
• Uremia sulphate/phosphate
• ASA salicylate
• Methanol formate
• E. Glycol oxalate

Lactic Acidosis
Why do we need oxygen?

• For oxidative phosphorylation

What is oxidative phosphorylation?

• ADP + P i = ATP (requires energy)
• The formation of ATP

What does the oxygen do?

Lactic Acidosis
Glycolysis:
Glucose "Pyruvate "Acetyl CoA
Kreb’s:
Acetyl CoA "NADH & FADH
Electron transport chain (ETC)
NADH & FADH "ATP

Lactic Acidosis

• The bulk of ATP is generated in the electron transport chain (ETC) in the mitochondrion
• The energy for creating the high-energy phosphate bond is generated at several points in the ETC. So are hydrogen ions

Metabolic Acidosis
(primary fall in serum bicarbonate)

Lactic Acidosis

• Type A: failure of oxidative phosphorylation (Pyruvate èLactate)
• Type B: lactate production overwhelms lactate metabolism

Lactic Acidosis  
Type A (more severe)
Failure of ETC:
Decreased Oxygen delivery
Shock of any type
Severe hypoxemia
Severe Anemia
Inhibitors (CO, CN)
 Back to original case
Arterial blood analysis:
pH 6.95, p aO 2 337, p aCO 2 44, TCO 2 10 H +102nM
Na 142, K 6.3, Cl 106 anion gap 26
Albumin 1.2g/dl
Expected anion gap 6 because of low albumin
Anion gap 20 above expected
Lactate 18.3meq/l
Minute ventilation 6.4 liters

Lactic Acidosis: Treatment

• Treat the underlying cause
• Lower the H + concentration

Lactic Acidosis: Treatment
Underlying cause in this case:
Profound rapid blood loss
Transfusion of blood and products
Circulatory support

Lactic Acidosis: Treatment
Lower the H + concentration
H + + HCO 3 - D H 2CO 3 D H 2O + CO 2
Lower the p aCO 2 by increasing minute ventilation

Lactic Acidosis: Treatment
Lower the p aCO 2 by
increasing
minute ventilation

Lactic Acidosis: Treatment
For every 1meq/l drop in HCO 3 - from 25, p aCO 2 should decrease by ~ 1 torr
“Normal” p aCO 2 in the face of HCO 3 - 10 is 25 (40 – 15) and not 40 torr

Lactic Acidosis: Treatment
Intravenous bicarbonate administration:
Pro: lowers H + concentration ( ›pH)
improves pressor response
improves myocardial function
Con: worsens intracellular acidosis
may worsen outcome
hypertonic

Lactic Acidosis: Treatment
Bottom line:
If there is adequate circulation
and if minute ventilation is appropriate,
some bicarbonate administration is
warranted.
Don’t aim for full correction, continue
arterial blood analysis

Metabolic Acidosis: Summary

• Definition
• Acid-Base physiology
• Anion gap
• Differential diagnosis of metabolic acidosis with high anion gap
• Lactic acidosis
• Oxidative phosphorylation
• Types of Lactic acidosis
• Treatment of Lactic Acidosis

Lactic Acidosis
take-home points
With hemodynamic instability:
Severe acute bleed
Sepsis
Trauma
Increase minute ventilation
Analyze arterial blood
Judicious intravenous NaHCO 3 -
 

Medical Transcription

Medical Transcription
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