Book 1, Case 8-Chronic Renal failure Flashcards
Anesthetic concerns in CRF pts?
his CRF increases his risk of electrolyte
abnormalities, metabolic acidosis, cardiac conduction blockade, L VH/CHF,
hyperglycemia, bleeding (uremia -7 impaired vWF -7 impaired platelet function),
and altered drug clearance; 5) electrolyte abnormalities (i.e. hyperkalemia,
hypocalcemia) may increase his risk of cardiac irritability and arrhythmia; and ( 6)
undergoing laparoscopy places him at risk for several associated complications, such
as capnothorax, trocar-induced trauma to bowel or blood vessels, pneumoperitoneum-
induced hypotension, and C02 emphysema.
How to assess vol status in CRF pts?
It would be helpful to
know how often this patient is dialyzed, when the last dialysis session occurred, and
how much fluid was taken off at that time.
Clinically, I would first look for signs or symptoms of fluid overload or hypovolemia.
Pulmonary edema, hypertension, peripheral edema, and jugular venous distension
(JVD) would suggest hypervolemia, while dry mucous membranes, hypotension, and
orthostasis would suggest hypovolemia.
CRF pt K+ is 5.6-you going back? What are you going to do about it? What about if it was 6.2?
The decision to cancel the case depends on the severity and chronicity
of the hyperkalemia as well as the urgency of surgery. While it is often
recommended to delay elective surgery when the potassium level exceeds 5 .5 mEq/L,
patients on dialysis often tolerate chronic hyperkalemia very well. Therefore, given
the urgent nature of this case, and assuming he was not symptomatic or showing signs
ofhyperkalemia on EKG (peaked T-waves, wide QRS, prolonged P-R interval, etc.),
I would correct any hypocalcemia (both are associated with
CRF); plan to avoid succinylcholine, potassium-containing solutions (LR), and metabolic or respiratory acidosis; prepare to treat hyperkalemia with calcium,
glucose/insulin, a beta-2 agonist, hyperventilation, and/or bicarbonate; make sure a
defibrillator was in the room; and proceed with the case while carefully monitoring
the EKG and potassium levels.
What I would do: 500 mg calcium chloride, or 1 gm calcium gluconate is enough to temporarily stabilize the heart from the effects of hyperkalemia
Shift K+ from plasma back into the cell: intravenous glucose (25 to 50 g dextrose, or 1-2 amps D50) plus 5-10 U regular insulin will reduce serum potassium levels within 10 to 20 minutes, and the effects last 4 to 6 hours, hyperventilation, β-agonists.
If it were 6.2: If the K+ were 6.2 mEq/L, I would prefer to dialyze the patient prior to
surgery (sometimes possible to undergo dialysis without heparin), but if the patient’s
condition was severe and surgery was considered emergent, I would proceed as I
previously described.
Mechanism of anemia in pts with chronic renal failure:
Why is it often well tolerated? What issues do they have with bleeding and why?
secondary to decreased erythropoietin production, decreased red cell survival,
gastrointestinal blood loss, and iron/vitamin deficiency. This is often well tolerated,
since CRF-:induced metabolic acidosis and increased levels of2,3-DPG cause a
rightward shift in the hemoglobin-oxygen dissociation curve, facilitating the
offloading of oxygen from hemoglobin. However, patients with CRF are prone to
increased perioperative bleeding secondary to heparin administration during
hemodialysis, and due to chronic platelet dysfunction.
You transfusing all of your renal patients before surgery?
No, the decision to transfuse depends on the severity of anemia, the
risk of excessive blood loss during surgery, and co-morbid disease, such as coronary
artery disease or uncompensated CHF. Assuming this patient does not have
significant coronary artery disease, mild anemia will most likely be well tolerated,
since CRF-induced metabolic acidosis and increased levels of 2,3-DPG cause a
rightward shift in the hemoglobin-oxygen dissociation curve, facilitating the
offloading of oxygen from hemoglobin. While hemoglobin levels of 11-12 g/dL are
recommended for patients with end-stage renal disease on dialysis (usually achieved
with erythropoietin or darbopoietin), there is :insufficient evidence to support routine
preoperative transfusion to achieve these recommended levels.
Blood transfusions and patients with kidney transplantation: You doing it? and if you do, what has to happen?
In the case of a patient with a transplanted kidney (not this patient), blood
transfusion should be avoided if possible, since exposure to leukocyte antigens in
the blood may lead to the development of alloantibodies, predisposing to rejection
of the implanted kidney. For this reason, if transfusion were deemed necessary in
a patient with a transplanted kidney, it is recommended that administered packed
red blood cells be washed Oeukocyte-reduced), irradiated (reduces the risk of
transfusion-associated graft-versus-host disease), and CMV negative (if the
recipient was CMV negative).
Are you concerned about renal patients and their cardiac function? If so-why? And…what would you do?
Yes I am concerned, since the volume overload, uremia, anemia, and acidosis associated with CRF can lead to HTN, CHF, conduction blocks, arrhythmias,
What would I do? I would perform a focused history and physical to identify symptoms such as angina,
syncope, orthopnea, arrhythmia, and functional status. If the results of the history and
physical suggested the need for further work up, I would consider an EKG, echo,
and/or cardiac consultation.
What do you tell renal pts about their risk of anesthesia:
I would explain that, due to his HTN, CRF, obesity, and.the emergent
nature of the surgery, his risk of experiencing perioperative complications such as
aspiration, difficult intubation, pharmacologic side effects, postoperative bleeding,
postoperative infection, and cardiac arrhythmias is somewhat increased.
What routine preoperative lab work would you order for someone with chronic
renal failure?
Laboratory requirements would depend on the type of surgery, the
patient’s medical conditions, and the planned anesthetic. In general, I would order a
CBC to assess anemia; an electrolyte panel to identify abnormalities in sodium,
calcium, and potassium; an EKG to look for hypertrophy, signs of ischemia, or
conduction disturbances; and a CXR to assess fluid overload and pulmonary status. If
the patient were dyspneic, I would consider ordering an ABG; if regional anesthesia
were being considered, I would order coagulation studies.
With bowel cases, don’t forget to place what before induction? Also, avoid what meds in SBO or perforated bowel stuff?
Don’t forget to place the NG tube!!!!
Avoid metoclopramide to prevent bowel rupture!!!!-don’t just always mechanically say that. Think about why you would or wouldn’t give that.
Are there any anesthetic drugs you would avoid in someone with CRF?
Some of these drugs include pancuronium, atropine, glycopyrrolate,
ketamine, morphine, diazepam, and meperidine. Also, the dosage of drugs that are
highly protein bound, such as thiopental and the benzodiazepines, should be reduced
in patients with CRF, as they may exert an exaggerated drug effect in the presence of
decreased protein binding.
A few minutes after intubation, the Sp02 decreases to 91 %, despite a Fi02 of
100%. What are the possible causes of his hypoxia?
What would you do? What needs to be done first in these situations (other than applying 100% O2)
The most likely causes of hypoxia shortly after intubation would
include inadequate ventilation, advancement of the ETT into the right mainstem
bronchus, and bronchospasm (the latter may occur secondary to light anesthesia
and/or aspiration). Other less likely causes would include changes in pulmonary
compliance with the supine position, atelectasis, obstruction of the ETT, or delivery
of a hypoxic gas mixture
begin by examining the oropharynx for gastric material,
making sure to suction and clear the airway ( oropharynx and ETT) before applying
positive pressure ventilation, which could further disseminate gastric material in the
lungs. Next, I would hand ventilate with 100% oxygen, confirm appropriate ETC02
and inspired 0 2 concentrations, and auscultate both lung fields. Depending on what I
found, I might pull back on the ETT, administer a bronchodilator, deepen my
anesthetic, increase the tidal volume, apply PEEP, or place the patient in the reverse
trendelenburg position.
How are you going to deal with volume losses in CRF patients?
In order to avoid fluid overload, I would replace insensible losses and
third space losses with an isotonic crystalloid (i.e. normal saline), limiting
replacement to 1-2 mL/kg/hr. With the same goal in mind, I would replace blood
losses using a colloid solution or packed red blood cells, rather than a 3: 1 ratio of
crystalloid. Given this patient’s hyperkalemia and probable glucose intolerance, I
would avoid the administration of lactated ringers (contains 4mEq/L of potassium)
and glucose containing solutions.
What are 3rd space losses and why do they occur?
Third spacing occurs when fluids in the intravascular compartment are
lost into the interstitial space due to traumatized, inflamed, or infected tissue. This
shifting of fluid occurs at the expense of the intracellular and intra vascular
compartments, requiring replacement. Estimates of these losses are often based on
the extent and type of surgery.
CRF patient:The patient’s blood pressure gradually declines to 82/60 mmHg, despite fluid
replacement. What would you do?
I would recheck the blood pressure, ensure adequate ventilation and
oxygenation, check the EKG for signs of ischemia or arrhythmia (i.e. peaked T-waves
and widening of the QRS associated with hyperkalemia), check the surgical field for
excessive bleeding, place the patient in the trendelenburg position, give a fluid bolus,
and consider administration of a vasoconstrictor.
