IVF Flashcards
A 28-year-old healthy man visits you at the clinic complaining of lower limb swelling that occurs at the end of his day. He is working in a factory in a position requiring standing for long periods. What’s the most probable cause if his lower limb swelling?
A. Increased capillary permeability
B. Increased intravascular hydrostatic pressure
C. Decreased intravascular osmotic pressure
D. Decreased venous return
E. Reduced lymphatic drainage
The correct answer is increased hydrostatic pressure. Edema is a common symptom encountered in outpatient clinics and it has several causes and several mechanisms. It may occur in certain diseases such as hepatic cirrhosis, renal failure, congestive heart failure, hypothyroidism, and it may occur in some physiological states. Under normal circumstances, intravascular fluid volume is maintained when there is a balance between the opposing forces that tend to keep the fluid in or push it out the vascular compartment. Edema results when there is imbalance between these opponent forces.
The intravascular osmotic pressure is the main force responsible for keeping the fluid inside the intravascular compartment and prevent its extravasation into the extravascular space, whereas the intravascular hydrostatic pressure forces the fluid to transudate out of the vessels to the extracellular space. Venous return, lymphatic drainage, and intact capillary wall integrity are essential for normal function of these opponent forces. In the patient described in the question, long periods of standing lead to pooling of blood to the lower extremity vasculature which subsequently results in an increase in intravascular hydrostatic pressure forcing the fluids to the extravascular compartment leading to local edema in the lower extremities.
A 73-year-old man, who is a chronic smoker, presents to the emergency department with a ruptured abdominal aortic aneurysm. He undergoes a successful repair of the ruptured aneurysm. During the surgery, he receives 8 liters of Ringer’s lactate solution and 4 units of whole blood. Which of the following statements best describes the effects of balanced crystalloid solutions?
A. Balanced crystalloids may lead to acidosis
B. Lactated crystalloid solutions are beneficial in severe liver failure
C. Excretion of excess water is faster with balanced crystalloids than with isotonic saline
D. Acetate-based crystalloids lower the risk of acetate intolerance in end-stage kidney disease
In comparison to isotonic saline, the excretion of excess water and electrolyte load is more rapid with balanced crystalloids. This is due to the transient reduction in plasma tonicity after infusion, which suppresses antidiuretic hormone (ADH) secretion and allows diuresis in response to the increased intravascular circulating volume. Balanced crystalloids do not reduce plasma strong ion difference (SID) to the same degree as NaCl solutions and therefore do not cause acidosis. The lactate present in Ringer’s lactate solution undergoes predominantly hepatic oxidation or gluconeogenesis to form bicarbonate ions.
The reliance on hepatic metabolism of most of the infused lactate means that lactated crystalloid solutions may lead to an accumulation of lactate in severe liver failure, and should, therefore, be avoided. Acetate turnover is limited in patients with end-stage kidney disease. It is, therefore, possible that such patients may exhibit biochemical acetate intolerance, although this possibility has not been explored in patients receiving acetate-based balanced crystalloids.
A 42-year-old gentleman is being planned for surgery with inhalational anesthesia. He wants to know about the possible adverse effects of nitrous oxide. Which of the following possibilities is not a potential effect of nitrous oxide?
A. Iron-deficiency anemia
B. Immunosuppression
C. Subacute combined degeneration of spinal cord (SACD)
D. Hyperhomocysteinemia
Common adverse effects of nitrous oxide include nausea, vomiting and diffusion hypoxia. However, its toxicity can lead to certain major complications and adverse effects.
Nitrous oxide toxicity is known to cause megaloblastic anemia, and not iron-deficiency anemia. Hence, option A (Iron-deficiency anemia) is the correct answer. Nitrous oxide is known to interfere with white blood cell function and hence, leads to immunosuppression. There is also a correlation between nitrous oxide exposure and hyperhomocysteinemia (due to inhibition of methionine synthetase), which is also a risk factor for coronary heart disease.
Nitrous oxide toxicity can lead to several neurological symptoms due to vitamin B12 malabsorption. Symptoms include tingling numbness, parasthesia, short-term impairment of mental performance, and peripheral neuropathy. Subacute combined degeneration of the spinal cord (SACD) is a serious manifestation of nitrous oxide toxicity. Individuals with B12 deficiency are at higher risk for these neurological adverse effects.
A blood sample for cross-matching should be collected before administration of which of the following?
A. 0.9% saline
B. Ringer Lactate
C. 5% Dextrose
D. Dextran
Colloid infusions are an alternative choice to crystalloid infusions for fluid maintenance. Common colloid infusions include albumin, dextran, gelatin and hydroxyethyl starch (HES).
Dextran is a synthetic colloid and the common solutions in use include Dextran 70 (molecular weight 70,000) and Dextran 40 (low molecular weight).
For the question here, option D is the correct answer as one of the adverse effects of dextran infusion is interference with cross-matching. Several studies have shown that dextran can layer on to the surface of red blood cells, forming a coat. This can interfere with cross-matching of blood prior to transfusion. Hence, it is recommended that a sample of blood for cross-matching and compatibility studies should be withdrawn prior to dextran infusion. Dextran can also cause an increase in erythrocyte sedimentation rate. Other adverse effects of dextran infusion include coagulation abnormalities, anaphylactic reactions, and precipitation of acute renal failure.
Other options are incorrect as they do not cause any interference in cross-matching.
2 liters of 0.9% saline was infused in a patient for fluid replacement. Which of the following is likely to occur post-infusion?
A. Decrease in K+ concentration
B. Decrease in HCO3- concentration
C. Decrease in Cl- concentration
D. Metabolic alkalosis
0.9% NaCl (normal saline) is a commonly used intravenous fluid. A large infusion of saline results in hemodilution and it causes a dilutional decrease in hemoglobin, albumin and hematocrit values by increasing the extracellular fluid volume. Rapid infusion of normal saline can also reduce renal perfusion.
Dilution acidosis is seen after saline infusion, likely due to excessive excretion of bicarbonate ions form the kidney. Hence, option B is the correct answer as saline infusion brings about a decrease in HCO3- concentration.
Option A is incorrect as normal saline infusion causes an increase in K+ concentration.
Similarly, option C is incorrect as the Cl- concentration is increased post-infusion of normal saline. Infusion of large amounts of saline causes metabolic acidosis due to a decrease in anion gap by increasing chloride concentration and bicarbonate excretion (hyperchloremic metabolic acidosis).
This is a major adverse effect of rapid infusion of 0.9% NaCl. Hence, option D is the incorrect answer.
A 40-year-old gentleman presents to the hospital with persistent vomiting. Which of the following changes occurs within minutes of vomiting-induced volume depletion?
A. Tachycardia
B. Bradycardia
C. Inhibition of aldosterone release
D. Increase in GFR (Glomerular Filtration Rate)
Volume depletion is a decrease in extracellular fluid volume, and causes can be renal (diuresis) or extrarenal (vomiting, diarrhea, burns, sepsis, etc.). Any alteration in intravascular volume leads to a sequence of events in the body, in an attempt to normalize the altered volume. With less than <5% volume loss, there is loss of skin turgor and feeling of thirst. With more volume loss up to 5% - 10%, the body tries to compensate by tachycardia, hypotension, further decrease in skin turgor. With fluid loss >10%, signs of shock appear such as poor capillary refill, altered mental state. If shock persists, irreversible organ damage can occur. Option A is the correct answer as tachycardia is seen from the early stages of volume depletion.
Option B is wrong as bradycardia is not seen in acute volume depletion.
Option C is wrong as volume depletion leads to renal vasoconstriction, which activates the renin-angiotensin-aldosterone axis, leading to aldosterone release and ADH production.
Option D is wrong as there is reduced urine production (reduced GFR) in volume-depleted states.
A 16-year-old girl visits you at the clinic with her friend. Her friend reports that she has just lost consciousness on the sight of blood. Which of the following reflexes is most probably responsible for her condition?
A. Baroreceptor reflex B. Bezold Jarish reflex C. Cushing reflex D. Oculocardiac reflex E. Bainbridge reflex
The most appropriate mechanism of her condition is stimulation of the baroreceptor reflex. The condition described in the question is vasovagal syncope. Vasovagal syncope or vasovagal response is a condition characterized by bradycardia, reduced cerebral blood flow, and consequently fainting via vagally-mediated cardio-inhibition. Under normal circumstances, vagus nerves transmit impulses from baroreceptors at aortic arch and carotid bodies to the brain stem to regulate arterial blood pressure. For instance, when blood is pooled to the lower extremities upon standing, the baroreceptors are inhibited leading to parasympathetic inhibition and consequently vasoconstriction to maintain blood pressure.
On the other hand, conditions that increase venous pool results in stimulation of vasovagal response leading to bradycardia and vasodilatation. The common precipitating factors of vasovagal response include sight of blood, sudden stress or pain, loss of blood, or surgical manipulation or trauma. Vasovagal syncope may occur suddenly without warning symptoms. However, the vast majority of patients report sense of weakness, yawning, lightheadedness, diaphoresis, nausea, blurred vision, or hyperventilation before fainting. Sitting or lying down help to prevent or abort the vasovagal syncope.
Total body mass Composed of;
40% solid
60% fluid and out of the fluid …
And what’s the ml/kg for blood volume and interstitial?
2/3 or 55% intracellular
1/3 or 45% extracellular
- 17% sequestrated ECF
— Bone & connective tissue
— Transulleular
- 27% fractional ECF —interstitial 20% (120-165 ml/kg) —intravascular 7% —-5% plasma (blood volume 60-65ml/kg) —-2% subglycocalyceal layer)
Oncotic pressure of plasma helps maintain intravascular volume
Daily maintenance requirement for adults
H2O
Na
Glucose
K
H2O 1.5 - 2.5 L
Na 50-100 mEq
Glucose 50-100 g
K 40 - 80 mEq
How much of the infused crystalalloids stays intravascular after 30 min of infusion (t1/2 of crystalloids?)
70% of infused crrystalloids stays intravascular after 20 min and 50% after 30 min of infusion
Response of fluid resuscitation to major blood loss seen after
12-72 hours of no ongoing bleeding and increase in hepatic plasma proteins synthesis and restore of RBC level by erythropoiesis within 4-8 weeks
And it takes several days for 20mL/kg of isotonic fluids to be fully excreted from body
4 categories to assess for perioperative fluid resuscitation are
1) fasting deficients
2) hourly maintenance
3) insensible loss
4) blood loss
What types of fluids that is closest to physiological pH
5% albumin, plasmanate, plasmaLyte (7.4)
NS and LR little acidic (6 and for LR 6.5)
What are the fluids that has potassium in it
Albumin <2.5
Plasmanate <2
LR & D5LR (4)
Normosol-R and plasmaLyte (most 5)
Na concentration in fluids?
154 -> NaCl & HES
145 -> albumin & plasmanate
140-> normosol & plasmaLyte
130 -> LR and D5LR
