Chapter 17: Fluids and Electrolytes- Third Spacing

Question 1

What is it?

Answer 1

Fluid accumulation in the interstitium of tissues, as in edema (think of the intravascular and intracellular spaces as the first two spaces)

Question 2

When does “third-spacing” occur postoperatively?

Answer 2

Third-spaced fluid tends to _mobilize back into the intravascul_ar space aroundPOD #3

Question 3

What are the classic signs of third spacing?

Answer 3

Tachycardia and Decreased urine output

Question 4

What is the treatment?

Answer 4

IV hydration with isotonic fluids

Question 5

What are the surgical causes of:

Metabolic acidosis

Answer 5

Loss of bicarbonate:​

• diarrhea
• ileus
• fistula
• high-output ileostomy
• carbonicanhydrase inhibitors

Increase in acids:

• lactic acidosis (ischemia)
• ketoacidosis
• renal failure
• necrotic tissue

Question 6

What are the surgical causes of:

Hypochloremic alkalosis

Answer 6

• NGT suction
• loss of gastric HCl through vomiting/NGT

Question 7

What are the surgical causes of:

Metabolic alkalosis

Answer 7

• Vomiting
• NG suction
• diuretics
• alkali ingestion
• mineralocorticoid excess

Question 8

What are the surgical causes of:

Respiratory acidosis

Answer 8

• Hypoventilation (e.g., CNS depression)
• drugs (e.g., morphine)
• PTX
• pleural effusion
• parenchymal lung disease
• acute airway obstruction

Question 9

What are the surgical causes of:

Respiratory alkalosis

Answer 9

Hyperventilation (e.g., anxiety, pain, fever, wrong ventilator settings)

Question 10

What is the “classic” acid–base finding with significant vomiting or NGT suctioning?

Answer 10

Hypokalemic and hypochloremic metabolic alkalosis

Question 11

Why hypokalemia with NGT suctioning?

Answer 11

Loss in gastric fluid—loss of HCl causes alkalosis, driving K+ into cells

Question 12

What is the treatment for hypokalemic and hypochloremic metabolic alkalosis?

Answer 12

IVF, Cl−/K+ replacement (e.g., NS with KCl)

Question 13

What is paradoxic alkalotic aciduria?

Answer 13

Seen in severe hypokalemic, hypovolemic, and hypochloremic metabolic alkalosis with paradoxic metabolic alkalosis of serum and acidic urine

Question 14

How does paradoxic alkalotic aciduria occur?

Answer 14

H+ is lost in the urine in exchange for Na+ in an attempt to restore volume

Question 15

With paradoxic alkalotic aciduria, why is H+preferentially lost?

Answer 15

H+ is exchanged preferentially into the urine instead of K+ because of the low concentration of K

Question 16

What can be followed to assess fluid status?

Answer 16

• Urine output
• base deficit
• lactic acid
• vital signs
• weight changes
• skin turgor
• jugular venous distention (JVD)
• mucosal membranes
• rales (crackles)
• central venous pressure
• PCWP
• chest x-ray findings

Question 17

With hypovolemia, what changes occur in vital signs?

Answer 17

• Tachycardia
• tachypnea
• initial rise in diastolic blood pressure because of clamping down (peripheral vasoconstriction)
  
  • with subsequent decrease in both systolic and diastolic blood pressures
• pulse pressure variability during inspiration on positive pressure ventilation

Question 18

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

Answer 18

Alphabetically and numerically: BGS and 123 or B1, G2, S3, because Bile,Gastric, and Small bowel produce roughly 1 L, 2 L, and 3 L, respectively!

Question 19

57-year-old man develops confusion and wide swings in heart rate and systolic blood pressure POD #2 after an appendectomy for a perforated appendix; sats = 99%, HCT stable, electrolytes normal, chest x-ray normal

Answer 19

Alcohol withdrawal

Question 20

34-year-old in the ICU s/p laparotomy with fascia closed, decreased urine output, increased peak airway pressure,decreased CVP, normal chest x-ray, normal EKG

Answer 20

Abdominal compartment syndrome

Question 21

A 77-year-old man s/p laparoscopic cholecystomy returns to theclinic with a palpable lower abdominal mass, confusion, and weak urine stream

Answer 21

Urinary retention

Question 22

74-year-old female s/p ex lap now POD #4 with acute onset ofshortness of breath; ABG reveals hypoxia and hypocapnia:

how do you diagnose

Answer 22

Chest CTA to rule out pulmonary embolism