First Aid for Surgery
Exam
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,What is the equation for plasma osmolality? 2[Na] + glucose/18 + BUN/2.8
Without any intake, what is a normal minimum urine Even without intake, you must excrete 800 mL/day in urine waste products.
output?
What is the most common fluid disorder? Volume deficit is most common.
What are some common causes of volume deficit? • Loss of GI fluid—vomiting, nasogastric suction, diarrhea, fistular drainage
• Third spacing: Intra-abdominal and retroperitoneal infection, peritonitis,
intestinal obstruction
• Burns
• Fever
• Osmotic diuresis
• Postoperative
• Inadequate input during procedure
How does dehydration affect the diagnosis of septic Volume depleted patients with severe sepsis from peritonitis may be afebrile and
patients? have normal white blood count (WBC), complain of little pain, and have
unremarkable findings on abdominal exam. This may change dramatically when
the ECF is restored.
How is the degree of dehydration assessed? It's dependent on acute loss of body weight and is assessed clinically:
• Mild—3% for adults, 5% for kids
• Moderate—6% for adults, 10% for kids
• Severe—9% for adults, 15% for kids
How do you treat dehydration? The initial intervention is to give a fairly large aliquot of fluid as a volume
expander. 20 mL/kg of normal saline or Ringer's lactate is given over the
first hour. During the remaining 8 hours, the expected maintenance fluid is
given plus about one half of the remaining calculated loss. Over the
remaining 16 hours, the other one half of the remaining calculated loss is
given along with the assumed maintenance fluid.
Which two IV solutions are given for volume expansion? Volume expansion can be accomplished with crystalloid (NaCl, Ringer's lactate,
D5W, etc.) or colloid (albumin, blood products).
How is crystalloid given for hypovolemia? The initial therapy is to give 2 L or 20 mg/kg bolus through two large-bore (>16
gauge in adults) IVs. Use isosmotic solutions to expand the intravascular space.
Since there is equilibration between ICF and ECF, only two thirds of any volume
of isotonic crystalloid will stay intravascularly.
What complication may arise when treating hypovolemia Large volumes may lead to peripheral and/or pulmonary edema.
with large volumes of fluid?
What complication may arise from treating hypovolemia Large amounts of dextrose may cause hyperglycemia.
with dextrose?
What complication may arise from treating hypovolemia Large amounts of NS may cause hyperchloremic metabolic acidosis.
with normal saline?
What complication may arise from giving LR to a LR given when the patient is hypovolemic and in metabolic alkalosis (NG tube,
hypovolemic patient with metabolic alkalosis? vomiting) may worsen the alkalosis when the lactate is metabolized.
,What are the indications for using colloid to replace fluid • If hypovolemia persists after 2 L of crystalloid.
volume? • Patients with excess Na and water, but are hypovolemic—such as ascites,
CHF, postcardiac bypass patients.
• Patients unable to synthesize enough albumin or other proteins to exert enough
oncotic pressure—such as liver disease, transplant recipients, resections,
malnutrition.
• Severe hemorrhage or coagulopathy—packed red blood cells (PRBCs) and
fresh frozen plasma (FFP) may increase hematocrit to help correct coagulopathy.
What are the issues with using colloid to correct volume • Possible increased incidence of pulmonary embolism respiratory failure
deficit? (controversial)
• Expensive
What is "third spacing"? Third spacing is the shift of ECF from the plasma compartment to elsewhere,
such as the interstitial or transcellular spaces.
What is the treatment for hypervolemia? • Restriction of Na/fluids for isotonic hypervolemia
• Free water replacement for hypertonic hypervolemia (corrects hypertonicity,
causing diuresis of excess fluid)
• Saline for hypotonic hypervolemia (correct hypotonicity, which should then
correct the hypervolemia)
• Diuresis with furosemide 10 to 50 mg (replace K as needed and do not
overuse)
• Cardiotonic drugs, O2, artificial ventilation for cardiac failure and respiratory
insufficiency as needed
How do you calculate a patient's fluids per hour? • Up to 10kg: 4 mL/kg/hr
• 11-20kg: 40 mL/hr + 2 mL/kg/hr for each kg above 10 kg
• >20kg: 60 mL/hr + 1 mL/kg/hr for each kg above 20 kg
How do you calculate a patient's fluids per day? • Up to 10kg: 100 mL/kg/day
• 11-20kg: 1,000 mL + 50 mL/kg/day for each kg above 10 kg
•>20kg: 1,500 mL+ 20 mL/kg/day for each kg above 20 kg
How do you calculate free water deficit? FWD = normal body water (NBW) − current body water (CBW)
How do you calculate normal body water? NBW = 0.6 × body weight in kg.
How do you calculate current body water? CBW = (NBW) [normal serum Na/measured serum Na].
What are the early signs of hypovolemia? • Tachycardia
• Decreased pulse pressure
• Orthostatic blood pressure (BP).
At what point does BP reflect hypovolemia? BP is not persistently lowered until 20-30% of circulating volume is lost.
What are the physical exam signs of hypovolemia? • Flat neck veins
• Poor tissue turgor
• Dry mucous membranes
• Cool extremities
What are the physical exam signs of hypervolemia? • Jugular venous distention (JVD)
• Rales
• S3
• Edema
What is the normal urine output for adults and children? • 0.5 cc/kg/hr for adults
• 1 cc/kg/hr for kids
, What are causes of high urine output? • Hypervolemia
• Diabetes insipidus
• Osmotic diuresis
• Post-obstructive diuresis
What are causes of low urine output? • Hypovolemia
• Renal failure
• Low flow states
How does BUN reflect volume level? • BUN/creatinine > 20 and FeNa < 1% indicates hypovolemia.
• BUN/Cr < 15 indicates adequate hydration.
What are the three kinds of hypotonic hyponatremia? • Hypovolemia diuretics or vomiting; often with K deficit
• Hypervolemia: CHF, cirrhosis, nephrotic syndrome; increased thirst and
vasopressin; edematous state
• Euvolemia: SIADH (most common cause of normovolemic hyponatremia),
glucocorticoid deficiency (Addison's disease), hypothyroidism, and primary
polydipsia
What are the signs of SIADH? SIADH results from increased vasopressin release from the posterior pituitary or
ectopic sources, causing decreased renal free water excretion:
• Hypo-osmotic hyponatremia
• Inappropriately concentrated urine (osmolality >100)
• Euvolemia
• Normal renal, adrenal, and thyroid function
It's caused by neuropsychiatric disorders, malignancies (especially lung), and
head trauma.
What are the causes of hypertonic hyponatremia? It's caused by rapid infusion of glucose or mannitol, causing increased osmotic
pressure that shifts fluid from the ICF to the ECF.
What are the symptoms of hypertonic hyponatremia? • Increased intracranial pressure—may induce HTN
• Hyperactive reflexes
• Muscle twitching
• Oliguric then anuric renal failure
• Salivation, lacrimation, watery diarrhea
What is the treatment for hypertonic hyponatremia? • Correct underlying disorder.
• Raise plasma Na (lower ICF volume); restrict water intake.
• ECF volume contraction—Na repletion with saline isotonic to the patient, in
order to avoid rapid changes in ICF volume.
What are the symptoms of hypernatremia? • Restlessness, weakness, delirium
• Hypotension and tachycardia
• Decreased saliva and tears
• Red, swollen tongue
• Fever
• Oliguria
What is the treatment for hypernatremia? Stop any ongoing water loss with correction of hypovolemia, if present. Replace
any water deficit with D5W. Correct half of the water deficit in the first 24 hours;
correct the remaining water deficit over next 1 to 2 days.
What are common causes of hypokalemia? • Excessive renal secretion
• Movement of K into cells.
• Prolonged administration of K-free parenteral fluids.
• Total parenteral hyperalimentation with inadequate K replacement.
• Loss in GI secretions.
• Diuretics
When does excessive renal K secretion occur? Renal tubular excretion of K increases when large quantities of Na are available
for excretion. So, the more Na available for reabsorption, the more K is
exchanged for Na in the lumen. Thus, the K required for prolonged or massive
isotonic fluid volume replacement is increased.
Exam
** 100% Guaranteed Pass
** Expert-Verified Explanation
** Questions with Verified Answer
** Latest Edition | Updated
,What is the equation for plasma osmolality? 2[Na] + glucose/18 + BUN/2.8
Without any intake, what is a normal minimum urine Even without intake, you must excrete 800 mL/day in urine waste products.
output?
What is the most common fluid disorder? Volume deficit is most common.
What are some common causes of volume deficit? • Loss of GI fluid—vomiting, nasogastric suction, diarrhea, fistular drainage
• Third spacing: Intra-abdominal and retroperitoneal infection, peritonitis,
intestinal obstruction
• Burns
• Fever
• Osmotic diuresis
• Postoperative
• Inadequate input during procedure
How does dehydration affect the diagnosis of septic Volume depleted patients with severe sepsis from peritonitis may be afebrile and
patients? have normal white blood count (WBC), complain of little pain, and have
unremarkable findings on abdominal exam. This may change dramatically when
the ECF is restored.
How is the degree of dehydration assessed? It's dependent on acute loss of body weight and is assessed clinically:
• Mild—3% for adults, 5% for kids
• Moderate—6% for adults, 10% for kids
• Severe—9% for adults, 15% for kids
How do you treat dehydration? The initial intervention is to give a fairly large aliquot of fluid as a volume
expander. 20 mL/kg of normal saline or Ringer's lactate is given over the
first hour. During the remaining 8 hours, the expected maintenance fluid is
given plus about one half of the remaining calculated loss. Over the
remaining 16 hours, the other one half of the remaining calculated loss is
given along with the assumed maintenance fluid.
Which two IV solutions are given for volume expansion? Volume expansion can be accomplished with crystalloid (NaCl, Ringer's lactate,
D5W, etc.) or colloid (albumin, blood products).
How is crystalloid given for hypovolemia? The initial therapy is to give 2 L or 20 mg/kg bolus through two large-bore (>16
gauge in adults) IVs. Use isosmotic solutions to expand the intravascular space.
Since there is equilibration between ICF and ECF, only two thirds of any volume
of isotonic crystalloid will stay intravascularly.
What complication may arise when treating hypovolemia Large volumes may lead to peripheral and/or pulmonary edema.
with large volumes of fluid?
What complication may arise from treating hypovolemia Large amounts of dextrose may cause hyperglycemia.
with dextrose?
What complication may arise from treating hypovolemia Large amounts of NS may cause hyperchloremic metabolic acidosis.
with normal saline?
What complication may arise from giving LR to a LR given when the patient is hypovolemic and in metabolic alkalosis (NG tube,
hypovolemic patient with metabolic alkalosis? vomiting) may worsen the alkalosis when the lactate is metabolized.
,What are the indications for using colloid to replace fluid • If hypovolemia persists after 2 L of crystalloid.
volume? • Patients with excess Na and water, but are hypovolemic—such as ascites,
CHF, postcardiac bypass patients.
• Patients unable to synthesize enough albumin or other proteins to exert enough
oncotic pressure—such as liver disease, transplant recipients, resections,
malnutrition.
• Severe hemorrhage or coagulopathy—packed red blood cells (PRBCs) and
fresh frozen plasma (FFP) may increase hematocrit to help correct coagulopathy.
What are the issues with using colloid to correct volume • Possible increased incidence of pulmonary embolism respiratory failure
deficit? (controversial)
• Expensive
What is "third spacing"? Third spacing is the shift of ECF from the plasma compartment to elsewhere,
such as the interstitial or transcellular spaces.
What is the treatment for hypervolemia? • Restriction of Na/fluids for isotonic hypervolemia
• Free water replacement for hypertonic hypervolemia (corrects hypertonicity,
causing diuresis of excess fluid)
• Saline for hypotonic hypervolemia (correct hypotonicity, which should then
correct the hypervolemia)
• Diuresis with furosemide 10 to 50 mg (replace K as needed and do not
overuse)
• Cardiotonic drugs, O2, artificial ventilation for cardiac failure and respiratory
insufficiency as needed
How do you calculate a patient's fluids per hour? • Up to 10kg: 4 mL/kg/hr
• 11-20kg: 40 mL/hr + 2 mL/kg/hr for each kg above 10 kg
• >20kg: 60 mL/hr + 1 mL/kg/hr for each kg above 20 kg
How do you calculate a patient's fluids per day? • Up to 10kg: 100 mL/kg/day
• 11-20kg: 1,000 mL + 50 mL/kg/day for each kg above 10 kg
•>20kg: 1,500 mL+ 20 mL/kg/day for each kg above 20 kg
How do you calculate free water deficit? FWD = normal body water (NBW) − current body water (CBW)
How do you calculate normal body water? NBW = 0.6 × body weight in kg.
How do you calculate current body water? CBW = (NBW) [normal serum Na/measured serum Na].
What are the early signs of hypovolemia? • Tachycardia
• Decreased pulse pressure
• Orthostatic blood pressure (BP).
At what point does BP reflect hypovolemia? BP is not persistently lowered until 20-30% of circulating volume is lost.
What are the physical exam signs of hypovolemia? • Flat neck veins
• Poor tissue turgor
• Dry mucous membranes
• Cool extremities
What are the physical exam signs of hypervolemia? • Jugular venous distention (JVD)
• Rales
• S3
• Edema
What is the normal urine output for adults and children? • 0.5 cc/kg/hr for adults
• 1 cc/kg/hr for kids
, What are causes of high urine output? • Hypervolemia
• Diabetes insipidus
• Osmotic diuresis
• Post-obstructive diuresis
What are causes of low urine output? • Hypovolemia
• Renal failure
• Low flow states
How does BUN reflect volume level? • BUN/creatinine > 20 and FeNa < 1% indicates hypovolemia.
• BUN/Cr < 15 indicates adequate hydration.
What are the three kinds of hypotonic hyponatremia? • Hypovolemia diuretics or vomiting; often with K deficit
• Hypervolemia: CHF, cirrhosis, nephrotic syndrome; increased thirst and
vasopressin; edematous state
• Euvolemia: SIADH (most common cause of normovolemic hyponatremia),
glucocorticoid deficiency (Addison's disease), hypothyroidism, and primary
polydipsia
What are the signs of SIADH? SIADH results from increased vasopressin release from the posterior pituitary or
ectopic sources, causing decreased renal free water excretion:
• Hypo-osmotic hyponatremia
• Inappropriately concentrated urine (osmolality >100)
• Euvolemia
• Normal renal, adrenal, and thyroid function
It's caused by neuropsychiatric disorders, malignancies (especially lung), and
head trauma.
What are the causes of hypertonic hyponatremia? It's caused by rapid infusion of glucose or mannitol, causing increased osmotic
pressure that shifts fluid from the ICF to the ECF.
What are the symptoms of hypertonic hyponatremia? • Increased intracranial pressure—may induce HTN
• Hyperactive reflexes
• Muscle twitching
• Oliguric then anuric renal failure
• Salivation, lacrimation, watery diarrhea
What is the treatment for hypertonic hyponatremia? • Correct underlying disorder.
• Raise plasma Na (lower ICF volume); restrict water intake.
• ECF volume contraction—Na repletion with saline isotonic to the patient, in
order to avoid rapid changes in ICF volume.
What are the symptoms of hypernatremia? • Restlessness, weakness, delirium
• Hypotension and tachycardia
• Decreased saliva and tears
• Red, swollen tongue
• Fever
• Oliguria
What is the treatment for hypernatremia? Stop any ongoing water loss with correction of hypovolemia, if present. Replace
any water deficit with D5W. Correct half of the water deficit in the first 24 hours;
correct the remaining water deficit over next 1 to 2 days.
What are common causes of hypokalemia? • Excessive renal secretion
• Movement of K into cells.
• Prolonged administration of K-free parenteral fluids.
• Total parenteral hyperalimentation with inadequate K replacement.
• Loss in GI secretions.
• Diuretics
When does excessive renal K secretion occur? Renal tubular excretion of K increases when large quantities of Na are available
for excretion. So, the more Na available for reabsorption, the more K is
exchanged for Na in the lumen. Thus, the K required for prolonged or massive
isotonic fluid volume replacement is increased.
