UBP 1.8 (Short Form): Renal – Chronic Renal Failure

Question 1

What concerns do you have in providing an anesthetic to this patient?

(A 64-year-old, 118 kg man is scheduled for an exploratory laparotomy for a suspected ruptured diverticulum. He has a 6-year-history of hypertension-induced chronic renal failure and is on hemodialysis. Medications include clonidine, metoprolol, erythropoietin, and Heparin with dialysis. VS: BP = 152/90 mmHg, P = 96, R = 20, T = 38.1 °C. Lab: Hgb = 9.2 g/dL, K = 5.6, Cr = 3.8 mEq/L.)

Answer 1

First, I am concerned about the urgency of the case, since this may limit the time I have to evaluate and optimize the patient.

Given his acute medical condition, which may be associated with nausea, vomiting, peritonitis, and even sepsis;

his chronic medical conditions, including – hypertension, obesity, anemia, and renal failure; and

the planned laparoscopic surgical approach, I have several specific concerns:

1. his obesity may make intubation and ventilation more difficult;
2. his obesity, abdominal condition, and possible diabetic neuropathy, may place him at increased risk of aspiration;
3. his chronic hypertension, anemia, probable hypovolemia, and probable vascular disease place him at increased risk of hemodynamic instability, inadequate perfusion, and subsequent end-organ damage (cardiac, cerebral, renal, etc.);
4. his CRF increases his risk of –
   
   • electrolyte abnormalities,
   • metabolic acidosis,
   • cardiac conduction blockade,
   • LVH/CHF,
   • hyperglycemia,
   • bleeding (uremia → impaired vWF → 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 CO2 emphysema.

Question 2

How would you assess this patient’s volume status?

(A 64-year-old, 118 kg man is scheduled for an exploratory laparotomy for a suspected ruptured diverticulum. He has a 6-year-history of hypertension-induced chronic renal failure and is on hemodialysis. Medications include clonidine, metoprolol, erythropoietin, and Heparin with dialysis. VS: BP = 152/90 mmHg, P = 96, R = 20, T = 38.1 °C. Lab: Hgb = 9.2 g/dL, K = 5.6, Cr = 3.8 mEq/L.)

Answer 2

Typically patients on hemodialysis are hypovolemic immediately following dialysis and hypervolemic prior to their next session.

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.

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Per Online UBP – If had the choice, may consider waiting >/= 12 hours after dialysis because of use of heparin and volume changes – if emergent/urgent, could ask to minimize heparin dosage/use.

Question 3

Would you cancel the case if the patient’s K+ was 5.6 mEq/L?

(A 64-year-old, 118 kg man is scheduled for an exploratory laparotomy for a suspected ruptured diverticulum. He has a 6-year-history of hypertension-induced chronic renal failure and is on hemodialysis. Medications include clonidine, metoprolol, erythropoietin, and Heparin with dialysis. VS: BP = 152/90 mmHg, P = 96, R = 20, T = 38.1 °C. Lab: Hgb = 9.2 g/dL, K = 5.6, Cr = 3.8 mEq/L.)

Answer 3

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 of hyperkalemia on EKG (peaked T-waves, wide QRS, prolonged P-R interval, etc.), I would –

• correct any metabolic acidosis or 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.

Question 4

What if the K+ were 6.2 mEq/L? (Would you cancel the case?)

(A 64-year-old, 118 kg man is scheduled for an exploratory laparotomy for a suspected ruptured diverticulum. He has a 6-year-history of hypertension-induced chronic renal failure and is on hemodialysis. Medications include clonidine, metoprolol, erythropoietin, and Heparin with dialysis. VS: BP = 152/90 mmHg, P = 96, R = 20, T = 38.1 °C. Lab: Hgb = 9.2 g/dL, K = 5.6, Cr = 3.8 mEq/L.)

Answer 4

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.

Question 5

What is the mechanism of anemia in patients with chronic renal failure?

(A 64-year-old, 118 kg man is scheduled for an exploratory laparotomy for a suspected ruptured diverticulum. He has a 6-year-history of hypertension-induced chronic renal failure and is on hemodialysis. Medications include clonidine, metoprolol, erythropoietin, and Heparin with dialysis. VS: BP = 152/90 mmHg, P = 96, R = 20, T = 38.1 °C. Lab: Hgb = 9.2 g/dL, K = 5.6, Cr = 3.8 mEq/L.)

Answer 5

Chronic anemia (usually a hemoglobin concentration of 6-8 g/dL) is secondary to –

• decreased erythropoeitin 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 of 2,3-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.

Question 6

Would you transfuse this patient prior to surgery?

(A 64-year-old, 118 kg man is scheduled for an exploratory laparotomy for a suspected ruptured diverticulum. He has a 6-year-history of hypertension-induced chronic renal failure and is on hemodialysis. Medications include clonidine, metoprolol, erythropoietin, and Heparin with dialysis. VS: BP = 152/90 mmHg, P = 96, R = 20, T = 38.1 °C. Lab: Hgb = 9.2 g/dL, K = 5.6, Cr = 3.8 mEq/L.)

Answer 6

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.

• –*
• Xtra Q – Why do you think CRF patients tolerate anemia so well??*

Clinical Note:Good to know:

• 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 (leukocyte-reduced), irradiated (reduces the risk of transfusion-associated graft-versus-host disease), and CMV negative (if the recipient was CMV negative).

Question 7

Are you concerned about this patient’s cardiac function?

How would you evaluate his cardiac status?

Is there any lab work that would be helpful?

How would the results alter your management?

(A 64-year-old, 118 kg man is scheduled for an exploratory laparotomy for a suspected ruptured diverticulum. He has a 6-year-history of hypertension-induced chronic renal failure and is on hemodialysis. Medications include clonidine, metoprolol, erythropoietin, and Heparin with dialysis. VS: BP = 152/90 mmHg, P = 96, R = 20, T = 38.1 °C. Lab: Hgb = 9.2 g/dL, K = 5.6, Cr = 3.8 mEq/L.)

Answer 7

Yes, I am concerned,

since the volume overload, uremia, anemia, and acidosis associated with CRF can lead to HTN, dilated cardiomyopathy, CHF, CAD, conduction blocks, arrhythmias, pericarditis, and even cardiac tamponade.

Therefore, 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.

Should this investigation reveal CAD or CHF, my fluid management, transfusion threshold, and intraoperative monitoring for this case may be altered.

*Per online UBP, ACC/AHA guidelines recommend EKG for high risk surgery (vascular) or high clinical risk factors.

Question 8

What would you tell this patient about his risks of anesthesia?

(A 64-year-old, 118 kg man is scheduled for an exploratory laparotomy for a suspected ruptured diverticulum. He has a 6-year-history of hypertension-induced chronic renal failure and is on hemodialysis. Medications include clonidine, metoprolol, erythropoietin, and Heparin with dialysis. VS: BP = 152/90 mmHg, P = 96, R = 20, T = 38.1 °C. Lab: Hgb = 9.2 g/dL, K = 5.6, Cr = 3.8 mEq/L.)

Answer 8

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.

I would assure him that steps would be taken to minimize these risks, and explain that a delay of surgery would carry significantly more risk while providing little benefit.

Question 9

What routine preoperative lab work would you order for someone with chronic renal failure?

(A 64-year-old, 118 kg man is scheduled for an exploratory laparotomy for a suspected ruptured diverticulum. He has a 6-year-history of hypertension-induced chronic renal failure and is on hemodialysis. Medications include clonidine, metoprolol, erythropoietin, and Heparin with dialysis. VS: BP = 152/90 mmHg, P = 96, R = 20, T = 38.1 °C. Lab: Hgb = 9.2 g/dL, K = 5.6, Cr = 3.8 mEq/L.)

Answer 9

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 (e.g. peaked T waves, widened QRS); and
• a CXR to assess fluid overload and pulmonary status.

If the patient were dyspneic, I would consider – ordering an ABG;

if regional were being considered, I would order – coagulation studies.