L14 Hypovolemia Therapy

Question 1

Indications for Intravenous Fluid Therapy?

Answer 1

Prevention of Hypovolemia

Treatment of Hypovolemic Septic Shock:

Correction of electrolyte disorders

Correction of Metabolic Alkalosis

Question 2

Physiologic Responses to Hypotension?

Answer 2

Constrict blood vessels to centralize blood
Retain sodium to retain more water and maintain blood pressure

Posterior pituitary releases vasopressin (normally regulated by serum sodium)
=> constricts arteriols
=> acts on renal tubules to reabosrob sodium

Catecholamines released from Adrenal Medulla
=> Vasoconstriction
=> sodium retention

Question 3

Therapy of Shock?

Answer 3

Initial therapy of hypotension ±shock should be with fluid bolus(-es), in the absence of volume overload/pulmonary oedema

In hypotensive patients who are unresponsive to fluid therapy, catecholamine vasoactive drugs are commonly required to support the circulation

Therapy of the cause of shock (bleeding, infection/sepsis, etc.) is also critically important

Question 4

Hypovolemic Shock Classification/Example/Treatment?

Answer 4

Low Cardiac Output States (SVR high): “Heart too empty”

Example: hemorrhagic shock

Therapy: blood transfusion, other intravenous fluids (crystalloids, colloids), stop the bleeding

Question 5

Cardiogenic Shock Classification/Example/Treatment?

Answer 5

Low Cardiac Output States (SVR high): “Heart too full”

Example: congestive heart failure with LV dysfunction

Therapy: drugs to improve ventricular contractility (inotropes) or reduce SVR (vasodilators, “afterload reducers”)

Question 6

Vasolodialatory Shock Classification/Example/Treatment?

Answer 6

High or Normal Cardiac Output (Low SVR)

Example: septic shock

Therapy: treat infection, intravenous fluids, sometimes inotropes (if cardiac output still low after fluid administration), sometimes vasopressors (which increase SVR and raise BP)

Question 7

Normal Saline (______% NaCl)
Slightly ________
Sodium(Na+): _________
Chloride(Cl-): __________
Buffer(Bicarbonate, Lactate, etc.): ______
Potassium(K+): ______
Other electrolytes (calcium, magnesium): _______

Answer 7

Normal Saline (.9% NaCl)
Slightly HYPERTONIC
Sodium(Na+): 154 mEq/liter
Chloride(Cl-): 154 mEq/liter
Buffer(Bicarbonate, Lactate, etc.): None
Potassium(K+): None
Other electrolytes: None

Question 8

Examples of Crystalloids?
Slightly HYPOTONIC
Sodium(Na+): _________
Chloride(Cl-): __________
Buffer(Bicarbonate, Lactate, etc.): ______
Potassium(K+): ______
Other electrolytes (calcium, magnesium): _______

Answer 8

Lactated Ringer’s solution, Hartmann’s solution, Plasmalyte
Slightly HYPOTONIC
Sodium(Na+): 131
Chloride(Cl-): 111
Buffer(Bicarbonate, Lactate, etc.): 29
Potassium(K+): 5.4
Other electrolytes: Calcium (Hartmans) Magnesium (Plasmalyte)

Question 9

Examples of Colloids?

Answer 9

Things included to increases osmolality DON”T LEAK OUT OF VESSEL AS MUCH=> Greater increase in blood volume
Human serum albumin
Artificial colloidal solutions:
Dextrans (glucose polymers)
Gelatin-based
Hydroxyethyl starches

Question 10

Indications for Blood Products?

Answer 10

Preferred if time allows. If patient unstable, normal saline given while waiting for blood panel

Whole blood or Packed red blood cells if bleeding or anemic

Fresh frozen plasma if coagulopathic, high INR (warfarin)

WATER GIVEN IN A VEIN LEADS TO HEMOLYSIS OF RBCs

Question 11

Indications for Blood Products?

Answer 11

Preferred if time allows. If the patient unstable, normal saline is given while waiting for a blood panel

Bleeding or anemic: Whole blood or Packed RBCs

Coagulopathic, high INR (warfarin): Fresh Frozen Plasma

Question 12

Distribution of IV FLuids?

Answer 12

Colloids: remain in intravascular space (in the presence of an intact capillary barrier)

Isotonic Crystalloids (normal saline, Hartmann’s, lactated Ringer’s): distribute throughout the ECF: 80% to the interstitium and only 20% to the intravascular space

5% dextrose (or oral water): distributes uniformly throughout ECF: 60% ICV, 40% ECV (8% intravascular)

0.45% saline: Distributes like an equal mixture of 0.9% saline and 5% dextrose

Question 13

To increase intravascular volume by 1
liter, infuse how much of each IV Fluid?

Answer 13

1 liter of colloid
5 liters of isotonic crystalloid
12 liters of 5% dextrose”

Need to infuse 4-5 fold higher volume of
crystalloid compared to colloid

Question 14

Complications of Intravenous Fluid Therapy?

Answer 14

IV access: site infection, bacteremia

Fluid contamination

Overaggressive in fluid delivery => FLUID OVERLOAD:
Fluid in lungs (Ventilation)
Fluid in tissue (Impairs wound healing/cardiac function)

Electrolyte Disorders (hyponatremia with 0.45% saline or 5% dextrose)
Dilute fluids given during surgery => risk of brain damage

Acid Base Disorders (hyperchloremic metabolic acidosis with 0.9% saline)

Question 15

IV fluids predisposing to risk of Hyponatremia?

Answer 15

0.45% saline or 5% dextrose

Question 16

IV fluids predisposing to risk of Acid/Base Disorders?

Answer 16

Hyperchloremic metabolic acidosis with 0.9% saline

Question 17

Role of the Endothelial Glycocalyx Layer in Use of Resuscitation Fluids?

Answer 17

Glycocalyx prevents leakage of fluids into extracellular space

Becomes leaky when sick (vasodilated in shcok conditions)

Shock can be worsened by overaggressive in giving fluids

Question 18

NEUROSURGERY TEAM WILL NOT GIVE __________ due to risk of leaking across BBB, causing water to follow behind worsening swelling in the brain

Answer 18

NEUROSURGERY TEAM WILL NOT GIVE ALBUMIN due to risk of albumin leaking across BBB, causing water to follow behind worsening swelling in the brain

Question 19

Signs of Hypovolemia Severity?

Answer 19

Hypotension (>30% loss of intravascular volume)

Orthostatic hypotension (>15% loss of intravascular volume)
Pulse increase > 20 bpm and/or BP decrease > 10mmHg with change from supine to sitting to standing (at any step)

Tachycardia, oliguria (Low urine output)
(>10-15% loss of intravascular volume)

Question 20

Initial therapy of hypotension ± shock should be with fluid bolus, in the absence of volume overload/pulmonary oedema _____________

Answer 20

Initial therapy of hypotension ± shock should be with fluid bolus, in the absence of volume overload/pulmonary oedema

Question 21

In hypotensive patients who are unresponsive to fluid therapy, ___________________ are commonly required to support the circulation

Answer 21

In hypotensive patients who are unresponsive to fluid therapy, catecholamine vasoactive drugs are commonly required to support the circulation