Surgical Recall Ch 17

Question 1

What are the two major body fluid compartments?

Answer 1

Intracellular

Extracellular

Question 2

What are the two subcompartments of extracellular fluid?

Answer 2

Interstitial (between cells)

Intravascular (plasma)

Question 3

What percentage of body weight is fluid?

Answer 3

60%

Question 4

What percentage of body fluid is intracellular?

Answer 4

66%

Question 5

What percentage of body fluid is extracellular?

Answer 5

33%

Question 6

What is the composition of body fluid?

Answer 6

60, 40, 20
60% of body weight is fluid
40% is intracellular
20% is extracellular

Question 7

On average, blood accounts for what percentage of ideal body weight in adults?

Answer 7

~7%

Question 8

How many liters of blood are in a 70-kg (154 lbs) man?

Answer 8

0.7 x 70 = 5 L

Question 9

What is the physiologic response to hypovolemia?

Answer 9

Sodium/water retention via renin –> aldosterone
Water retention via ADH
Vasoconstriction via angiotensin II and sympathetics
Low urine output
Tachycardia (early) and hypotension (late)

Question 10

What is third spacing?

Answer 10

Fluid accumulation in the interstitium (edema)

Question 11

When does third-spacing occur postoperatively?

Answer 11

Third-spaced fluid tends to mobilize into the intravascular space around post-op day 3

Question 12

What are the classic signs of third spacing?

Answer 12

Tachycardia

Decreased urine output

Question 13

What is the treatment for third spacing?

Answer 13

IV hydration with isotonic fluids

Question 14

What are the surgical causes of metabolic acidosis?

Answer 14

Loss of bicarb (diarrhea, ileus, fistula, high-output ileostomy, carbonic anhydrase inhibitors)
Increase in acids (lactic acidosis 2/2 ischemia, ketoacidosis, renal failure, necrotic tissue)

Question 15

What are the surgical causes of hypochloremic alkalosis?

Answer 15

NGT suction

Loss of gastric HCl through vomiting or NGT

Question 16

What are the surgical causes of respiratory acidosis??

Answer 16

Hypoventilation (CNS depression)
Drugs
Pneumothorax
Pleural effusion
Parenchymal lung disease
Acute airway obstruction

Question 17

What are the surgical causes of respiratory alkalosis?

Answer 17

Hyperventilation (anxiety, pain, fever, wrong ventilator settings)

Question 18

What is the classic acid-base finding with significant vomiting or NGT suctioning?

Answer 18

Hypokalemic and hypochloremic metabolic alkalosis

Question 19

Why does hypokalemia occur with NGT suctioning?

Answer 19

Loss of gastric fluid (loss of HCl) causes alkalosis which drives K+ into cells

Question 20

What is the treatment for hypokalemic and hypochloremic metabolic alkalosis?

Answer 20

IV fluids

Cl-/K+ replacement (e.g. NS with KCl)

Question 21

What is paradoxic alkalotic aciduria?

Answer 21

Severe hypokalemic, hypovolemic, and hypochloremic metabolic alkalosis of serum but acidic urine

Question 22

How does paradoxic alkalotic aciduria occur?

Answer 22

In an attempt to restore volume, H+ is lost in exchange for Na+

Question 23

Why is H+ preferentially lost in paradoxic alkalotic aciduria?

Answer 23

There is a low concentration of K+ so H+ is exchanged preferentially

Question 24

What can be followed to asses fluid status?

Answer 24

Urine output
Base deficit
Lactic acid
Vital signs
Weiht changes
Skin turgor
Jugular venous distention
Mucosal membranes
Rales / crackles
Central venous pressure
PCWP
Chest x-ray findings

Question 25

What vital sign changes are seen with hypovolemia?

Answer 25

Tachycardia
Tachypnea
Initial rise in diastolic blood pressure due to clamping down (peripheral vasoconstriction), subsequent decrease in both systolic and diastolic blood pressures
Pulse pressure variability during inspiration on positive pressure ventilation

Question 26

How can the estimated levels of daily secretions from bile, gastric, and small-bowel sources be remembered?

Answer 26

BGS, 123
B1, G2, S3
Bile - 1L
Gastric - 2L
Small bowel - 3L