Fluid and Electrolyte Management of the Surgical Patient

Question 1

Causes ofMetabolic acidosis with a normal anion Gap

Answer 1

• GI losses (loss of bicarbonate)
  
  • diarrhea
  • fistulas
• Acid administrion (HCL or NH4)
• Renal loss

the bicarbonate loss is accompanied by gain of chloride thus the AG remains unchanged

Question 2

Possible causes of Postoperative hyponatremia

Answer 2

• Excess infusion of normal saline intraoperatively
• Administraion of antipsychotic medication
• Excess oral water intake

ADH can be released transiently postoperatively or less frequently in syndrome of inappropriate ADH secretion

Question 3

Possible causes of pseudohyponatremia in laboratory testing

Answer 3

• High serum glucose, lipid or protein levels

Question 4

ECG findings in Hyperkalemia

Answer 4

• Peaked T waves (early change)
• Flattened P wave
• Prolonged PR interval
• widened QRS
• Sine wave formation
• Ventricular fibrillation

Question 5

Hypocalcemia may cause ______

Answer 5

• Congestive heart failure (decreased cardiac contractility)
• muscle cramping
• paresthesias

Question 6

ECG changes of hypocalcemia

Answer 6

• prolonged QT interval
• T wave inversion
• heart block
• Ventricular fibrillaion

Question 7

Causes hypocalcemia

Answer 7

• hypoparathyroidism
• severe pancreatitis

Question 8

Causes of metabolic acidosis with increased anion Gap

Answer 8

• Exogenous acid production
• Endogenous acid production (B-hydroxybutyrate and acetoacetate, lactate
• Renal insufficiency (organic acids)

Question 9

Hypertonic saline

Answer 9

• 7.5%
• treatment modality in patients with closed head injuries
• should not be used for initial resucitation
• Arteriolar vasodilator and may increase bleeding
• Increases cerebral perfusion

Question 10

Normal saline

Answer 10

• 154 mEq NaCl/L
• 154 mEq of chloride
• Mildy hypertonic
• used in correcting volume deficits associated wit
  
  • hyponatremia
  • hypochloremia
  • metabolic alkalosis

Question 11

Albumin for fluid resuscitation

Answer 11

• Can cause pulmonary edema
• Available as
  
  • 5% (300 mOSm/L)
  • 25% (1500 mOsm/L)

Question 12

Solutions associated withh postoperative bleeding in cardiac and neurosurgery patients

Answer 12

Hydroxyethyl starch solutions

Question 13

Water constitutes ____ percentage of total body weight

Answer 13

50-60%

Question 14

Highest percentaage of TBW is found _______

Answer 14

newborns (80%)

Decreases to 65 % by 1 year

Question 15

Serum Osmolality

Answer 15

2 sodium + glucose/18 + BUN/2.8

• Absite question: if glucose increased by 180 = serum osmolality will increase by 10

Question 16

Effect of pH to potassium

Answer 16

Potassium decreases by 0.3 mEq/L for every 0.1 increase in pH above normal

• Absite question:
  
  • pH 7.8
  • K: 2.2
  • answer K: 3.4

Question 17

Free water deficit

Answer 17

Water Deficit (L) = (serum sodium-140)/140 x TBW

• TBW
  
  • 50% in men
  • 40% in women

Absite question:

• 70kg
• sodium is 154
• answer: 7L

Question 18

Corrected Calcium

Answer 18

Adjust total serum calcium down by 0.8 mg/dl for every 1 g/dL decrease in albumin

Absite question:

• corrected calcium : 6.8
• albumin : 1.2
• total calcium : 9.2

Question 19

treatment for hyperkalemia that doesnt reduce serum K level

Answer 19

Calcium

• Calcium chloride or calcum gluconate (5-10 ml of 10% solution) should be administed immediately to counteract myocardial effects of hyperkalemia
• glucose and bicarbonate shift potassium intracellularlarly
• Kayexalate is cation exchane resin that binds potassium

Question 20

Magnesium correction

Answer 20

magnesium deficit = Desired - Actual

• target Mg is usually 1 for patients with cardiac disease otherwise target is 0.8
• 1g MgSO4 is given per 0.1 mmol/L Mg
  
  • MgSO4 drip in D5W

Question 21

Causes of hypomagnesemia

Answer 21

• Poor intake
• alcoholism
• prologed use of IV fluids and total parenteral solution
• GI losses
• Malabsortiop
• Acute pancreatitis
• DKA
• primary aldosteronism

Question 22

Daily maintenace fluids

Answer 22

Holliday segar

• First 10 kg = 100 ml/kg/day
• next 10-20 kg = 50 ml/kg/day
• each kg >20 kg = 20 ml/kd/ay (15 if elederly or with cardiac disease)

ml/kg/hr: 4/2/1

absite question:

• 60kg
• answer 2100

Question 23

Signs of hypocalcemia

Answer 23

• Trosseau sign ( spams resulting from pressure applied to the nerves and vessels on the upper extremity)
• Chvostek sign ( spasm resulting from tapping over the facial nerve)

Question 24

Asymptomatic hypocalcemia

Answer 24

Asymptomatic hypocalcemia may occur with hypoprotenemia

Symptoms do not occur until the ionized fraction falls below 2.5 mg/dL

Question 25

Corrected Anion Gap

Answer 25

Corrected = actual + [2.5(4.5-albumin)] Absite question: * Na 133 * K 4 * Cl 101 * HCO3 22 * Albumin 2.5 * ANSWER: **15**

Question 26

Effective osmotic pressure between plasma and intestitial fluid compartments is controlled primarily by

Answer 26

Protein

Question 27

The metabolic derrangement most commonly seen in patients with profuse vomiting

Answer 27

**Hypochloremic, hypokalemic metabolic acidosis** * isolated loss of gastric contents in infants with pyloric stenosis or in adults with duodenal ulcer disease = **metabolic alkalosis**

Question 28

Symptoms and signs of extracellular fluid volume deficit

Answer 28

Anorexia Apathy Decreased body temperature tachycardia orthostasis/hypotension oliguria ileus azotemia * EXCESS ECF * High pulse pressure * Weight gain * Edema * Increased CO * Increased central venous pressure * Distended neck veins * murmur * bowel edema * Pulmonary edema

Question 29

A low urinary NH4 with a hyperchloremic acidosis indicates what cause?

Answer 29

Renal tubular acidosis

Question 30

When lactic acid is produced in response to injury, the body minimizes pH change by \_\_\_\_\_\_\_\_

Answer 30

Excreting carbon dioxide through the lungs * Lactic acid reacts with base bicarbonate to produce carbonic acid - . broken down into water and cO2 - \> lungs

Question 31

Predicted Changes in Acid-Base disorders

Answer 31

Question 32

Characteristic findings of acute renal failure

Answer 32

* Hyperkalemia * Severe acidosis * Uremic pericarditis * Uremic encephalopathy Elevation of BUN is commonly seen as well but is not itself an indication for dialysis

Question 33

Relationship of glucose and sodium

Answer 33

For each 100mg/dL rise in blood glucose above the normal, serum sodium falls aprroximately 3 meq/L ## Footnote and vice versa

Question 34

Excessibe administration of normal saline for fluid resuscitation can lead to what metabolic derangement?

Answer 34

Metabolic Acidosis

Question 35

The first step in the management of acute hypercalcemia

Answer 35

Correction of deficit of extracellular fluid volume

Question 36

In patients suffering from hemorrhagic shock and metabolic acidosis. this fluid is recommended

Answer 36

Lactated ringers * Balanced salt solution * Restore perfusion * Correct metabolic acidosis by ending anerobic metabolism

Question 37

Refeeding syndrome

Answer 37

Shift in metabolism from fat to carbohydrate substrate stimulates insuin release, which results in the cellular uptakeof electrolytes particuarly phosphate, AMgnesium, Potassium, and calcium