Chapter 23 - IV Fluids and Electrolytes Seth Christian, MD MBA Tulane University Hospital and Clinic Seth Christian, MD MBA Tulane University Hospital

Chapter 23 - IV Fluids Chapter 23 - IV Fluids and Electrolytesand Electrolytes

Chapter 23 - IV Fluids Chapter 23 - IV Fluids and Electrolytesand Electrolytes

Seth Christian, MD MBASeth Christian, MD MBATulane University Hospital and ClinicTulane University Hospital and Clinic

Seth Christian, MD MBASeth Christian, MD MBATulane University Hospital and ClinicTulane University Hospital and Clinic

Overview of Fluid and Overview of Fluid and Electrolyte PhysiologyElectrolyte PhysiologyOverview of Fluid and Overview of Fluid and Electrolyte PhysiologyElectrolyte Physiology

•Perioperative Fluid Balance

•Fluid Replacement Solutions

•Perioperative Fluid Strategies

Perioperative Fluid Perioperative Fluid BalanceBalance


•Water represents 60% of TBW

•1 Kg = 1 L

•70 kg = 70 L

•60% of 70 L = 42 L water



•Intracellular Water (2/3 = 28 L)

•Extracellular Water (1/3 = 14 L)

•Blood Volume (5L)

•Interstitial Volume (9 L)

•Arterial Blood: Venous = 15:85

•Oncotic Pressure = 20 mmHg



•Maintenance Requirements

•1.5 to 2.5 L of water

•50-100 mEq Na

•40-80 mEq K







•NPO Deficit

•Maintenance Rate

•Insensible Loss and 3rd Spacing

•Blood Loss

Fluid Replacement Fluid Replacement SolutionsSolutions


•Crystalloids

•NS, LR, Plasmalyte

•Distribute freely within intravascular and interstitial compartments

•Only 1/3 remains intravascular





•0.9% "Normal" Saline

• Slightly hypertonic (154 mEq)

•Large volumes result in hyperchloremic (154mEq) non-gap metabolic acidosis

•Preferred for neurosurgery (Na) and ESRD patients(K) and for transfusions (no Ca)

•Hypertonic saline rarely used in OR, but has a role in trauma resuscitation to limit the total volume

Interesting Tid-BitInteresting Tid-BitInteresting Tid-BitInteresting Tid-Bit

•Daily Na Allowance = 2400 mg

•Big Mac w/Fries = 1500 mg

•1 L 0.9% Saline = 9000 mg



•Lactated Ringers (balanced salt solution)

•Slightly hypotonic (Na 130)

•Chloride ( )

•K (4)

•Mg ( )

•pH = 6.5

•Lactate metabolized to bicarbonate





•Colloids (albumin, hetastarch)

•Oncotic Pressure = 30-35 mmHg

•Replace blood loss with albumin 1:1 ratio

•Half life in circulation normally 16 hours.

•Half life can be as short as 2-3 hours in pathophysiologic conditions

•More expensive than crystalloid, but less expensive than blood

•Infectious complications are negligible



•5% Albumin

•Colloid oncotic pressure = 20 mmHg

•Preparation removes viruses and bacteria

•Albumin has minimal effects on coagulation



•6% Dextran 70

•The last number indicates the molecular weight in kDa

•Polymers synthesized from sucrose by certain bacteria

•Dextran 40 is used in vascular surgery to prevent thrombosis

•Side effects: anaphylactic and anaphylactoid reactions and increased bleeding (>20ml/kg/day) and rouleaux formation (interferes with cross-matching blood) and rare cases of noncardiac pulmonary edema



•Hydroxyethyl Starch (HES)

•Synthetic colloids that are modifications of natural polysaccharides

•Molecular weight

•Molar substitution (per 10 glucose units)

•C2 to C6 ratio

•Hetastarches have 7 substitutions per 10 glucose (0.7)

•The higher the molecular weight and molar substitution more prolonged intravascular time AND potential complications

•HES preparations with high C2 to C6 ratios have prolonged duration of action without increasing side effects



•HES preparations are described by their concentration, average molecular weight, and molar substitution.

•Hespan is 6% HES 450/0.7

•Hextend is 6% HES 670/0.7

•Voluven is 6% HES 130/0.4



•Hydroxyethyl Starch Complications

•Coagulation disturbances (interferes with vW factor, factor VIII, and platelet function)

•Renal toxicity (larger, older formulations)

•Tissue storage (pruritis)

Crystalloids versus Crystalloids versus ColloidsColloids

Crystalloids versus Crystalloids versus ColloidsColloids

•Proponents of crystalloids argue that albumin molecules normally enter the pulmonary interstitial compartment freely and then are cleared through the lymphatic system returning to systemic circulation. Additional albumin merely increases the albumin poo cleared by the lymphatics.

•The largest RCT of saline versus albumin fluid resuscitation involved 7000 patients in the intensive care population and showed no difference in any major outcome.

•A subgroup of patients with traumatic brain injury had increased mortality rate in the albumin group. It may be prudent to minimize the use of albumin in this patient population.

Perioperative Fluid Perioperative Fluid StrategiesStrategies


•The traditional approach was developed over 40 years ago.

•The guidelines represent a starting point for initiating therapy.

•Conservative fluid strategies are often employed for patients undergoing lung surgery, liver resection, and bowel resection.



•Conservative Fluid Strategies

•Replace blood loss on a 1:1 ratio with colloid

•No replacement of insensible losses or urine output during surgery

•No fluid loading prior to epidural analgesia

•Administer colloid bolus for signs of hypovolemia

•Definitions of "liberal" and "restrictive" fluid regimens are not standardized.



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Chapter 23 - IV Fluids and Electrolytes Seth Christian, MD MBA Tulane University Hospital and Clinic Seth Christian, MD MBA Tulane University Hospital