UBP 3.8 (Short Form): Renal – CRF & Kidney Transplant

Question 1

Are you concerned about this patient’s blood pressure?

(A 42- year-old, 84 kg, man with an 8-year history of chronic renal failure is brought to the operating room for nephrectomy and cadaveric kidney transplantation harvested 16 hours ago. He has a functioning AV fistula in the left forearm and received dialysis 24 hours ago. The nurse states he is extremely anxious. Medications include nifedipine, lisinopril, ranitidine, and OTC antacids. Vital Signs: P = 95, BP = 195/115 mmHg, RR = 22, T = 37 °C)

Answer 1

I am concerned because this patient with stage 3 hypertension (>/= 180/110 mmHg) with renal failure may be at increased perioperative risk for –

• blood pressure lability,
• myocardial ischemia,
• dysrhythmias,
• congestive heart failure,
• stroke, and
• other end-organ ischemia.

Therefore, I would:

1. perform a focused history and physical to identify any additional end-organ damage (i.e. left ventricular hypertrophy or a strain pattern on ECG);
2. obtain an ECG, electrolyte panel, blood urea nitrogen, and creatinine to further evaluate end-organ damage and identify metabolic derangements resulting from medications used in the treatment of hypertension; and
3. consult the transplant team to determine how long I could reasonably delay this urgent case to achieve better control of the patient’s blood pressure, recognizing that longer graft cold-ischemia periods can lead to delayed, impaired, or even failed graft function.

My treatment goal would be to carefully reduce the patient’s blood pressure to less than 160/110 mmHg over several hours, while avoiding end-organ hypoperfusion.

Additionally, I would administer a B-blocker to reduce the risk of perioperative hemodynamic lability and myocardial ischemia.

Question 2

What is your cut off blood pressure for cancelling a case?

(A 42- year-old, 84 kg, man with an 8-year history of chronic renal failure is brought to the operating room for nephrectomy and cadaveric kidney transplantation harvested 16 hours ago. He has a functioning AV fistula in the left forearm and received dialysis 24 hours ago. The nurse states he is extremely anxious. Medications include nifedipine, lisinopril, ranitidine, and OTC antacids. Vital Signs: P = 95, BP = 195/115 mmHg, RR = 22, T = 37 °C)

Answer 2

In making a decision to delay or cancel a case, I would weigh the benefits of blood pressure optimization against the risk of delaying surgery.

The evidence suggests that patients with stage 1 hypertension (140-150/90-99 mmHg) or stage 2 hypertension (160-179/100-109 mmHg) may be more prone to perioperative ventricular dysrhythmias, myocardial ischemia, and blood pressure lability.

However, they do NOT appear to be at increased risk of worsening perioperative outcomes such as stroke, myocardial infarction, renal failure, and death.

Unfortunately, there may be increased perioperative risk of major cardiovascular complications for patients with concomitant end-organ damage (renal insufficiency or left ventricular hypertrophy) and/or stage 3 hypertension (>/= 180/110 mmHg).

Additionally, patients with blood pressures greater than 140/90 mmHg who are undergoing cardiac surgery, carotid surgery, or pheochromocytoma resection, may also be at increased risk for major perioperative complications.

Therefore, I would prefer to delay elective surgery for at least 6-8 weeks to optimize the blood pressure of any patient who:

1. has stage 3 baseline hypertension,
2. has stage 1 or stage 2 hypertension with concomitant end-organ damage, and/or
3. is undergoing cardiac surgery, carotid surgery, or pheochromocytoma resection.

However, as I mentioned, the decision to delay any case (and the length of that delay) must weigh the risks of blood pressure optimization against the risk of surgical delay.

In the case of emergency surgery, I would carefully reduce the patient’s blood pressure to less than 160/110 mmHg and ensure adequate B-blockade (if not contraindicated) to reduce the risk of perioperative hemodynamic lability and myocardial ischemia, while avoiding end-organ hypoperfusion.

Question 3

Will you treat this blood pressure prior to proceeding with the case?

(A 42- year-old, 84 kg, man with an 8-year history of chronic renal failure is brought to the operating room for nephrectomy and cadaveric kidney transplantation harvested 16 hours ago. He has a functioning AV fistula in the left forearm and received dialysis 24 hours ago. The nurse states he is extremely anxious. Medications include nifedipine, lisinopril, ranitidine, and OTC antacids. Vital Signs: P = 95, BP = 195/115 mmHg, RR = 22, T = 37 °C)

Answer 3

Given the potential perioperative risks associated with severe baseline hypertension, I would –

• make the transplant team aware of my concerns,
• determine how long I could reasonably delay this urgent case,
• carefully reduce the patient’s blood pressure to less than 160/110 mmHg (over several hours, if possible, to avoid inducing end-organ ischemia),
• ensure adequate B-blockade to reduce the risk of perioperative hemodynamic lability and myocardial ischemia, and
• proceed with the case.

Assuming there were no contraindications, I would treat this hypertension with a short acting beta-blocker like esmolol and, if that were not effective, consider a more potent vasodilator such as sodium nitroprusside.

Question 4

How would you assess this patient’s volume status?

(A 42- year-old, 84 kg, man with an 8-year history of chronic renal failure is brought to the operating room for nephrectomy and cadaveric kidney transplantation harvested 16 hours ago. He has a functioning AV fistula in the left forearm and received dialysis 24 hours ago. The nurse states he is extremely anxious. Medications include nifedipine, lisinopril, ranitidine, and OTC antacids. Vital Signs: P = 95, BP = 195/115 mmHg, RR = 22, T = 37 °C)

Answer 4

In assessing this patient’s volume status, I would –

• look at his vital signs,
• take into consideration the time of his last dialysis (dialysis-dependent patients should be dialyzed before renal transplant surgery),
• compare his current weight with previous predialysis and postdialysis weights, and
• examine the patient for signs of either hypovolemia or hypervolemia.

Signs of hypervolemia include:

• pulmonary edema,
• hypertension,
• peripheral edema, and
• JVD;

while signs of hypovolemia include –

• dry mucous membranes,
• hypotension,
• tachycardia, and
• orthostasis.

Proper volume assessment is important for these patients at risk for both hypervolemic and hypovolemic complications.

While over-aggressive hydration can lead to –

• congestive heart failure and pulmonary edema,

inadequate replacement may result in –

• intra-operative hypotension, end-organ ischemia, and/or post-operative acute tubular necrosis (ATN).

In fact, maintaining adequate intravascular volume is associated with –

• earlier onset of graft function,
• reduced incidence of delayed graft function, and
• improved graft survival.

Question 5

Is a potassium level of 5.2 mEq/L significant in this patient with chronic renal failure?

(A 42- year-old, 84 kg, man with an 8-year history of chronic renal failure is brought to the operating room for nephrectomy and cadaveric kidney transplantation harvested 16 hours ago. He has a functioning AV fistula in the left forearm and received dialysis 24 hours ago. The nurse states he is extremely anxious. Medications include nifedipine, lisinopril, ranitidine, and OTC antacids. Vital Signs: P = 95, BP = 195/115 mmHg, RR = 22, T = 37 °C)

Answer 5

It is significant, because a potassium level above 5.0 mEq/L represents hyperkalemia.

Since significant hyperkalemia places the patient at risk of skeletal muscle weakness and delayed cardiac depolarization with potential progression to respiratory failure, ventricular fibrillation, and ventricular asystole,

elective surgery should be delayed when potassium levels exceed 5.5 mEq/L.

This patient’s hyperkalemia is likely chronic in nature, which is better tolerated than an acute increase in plasma potassium.

Therefore, I would proceed with this case despite his elevated potassium, recognizing that there is some additional risk due to the added potassium load following the washout of potassium-containing preservative solution from the newly perfused kidney.

If his potassium level were >/= 5.5 mEq/L, I would delay surgery for dialysis and correction of this electrolyte disturbance.

Fortunately, current preservation techniques allow for up to 48 hours of cold-ischemia time prior to transplant, providing sufficient time for pre-operative dialysis.

Question 6

What would be your choice of anesthesia for this case?

(A 42- year-old, 84 kg, man with an 8-year history of chronic renal failure is brought to the operating room for nephrectomy and cadaveric kidney transplantation harvested 16 hours ago. He has a functioning AV fistula in the left forearm and received dialysis 24 hours ago. The nurse states he is extremely anxious. Medications include nifedipine, lisinopril, ranitidine, and OTC antacids. Vital Signs: P = 95, BP = 195/115 mmHg, RR = 22, T = 37 °C)

Answer 6

Kidney transplant has been successfully performed under regional anesthesia.

However, the subsequent sympathectomy may complicate systemic blood pressure management, and uremic platelet dysfunction and/or residual heparin from preoperative dialysis may increase the risk of neuraxial hematoma.

Therefore, assuming he did not have a difficult airway, I would choose to provide a balanced general anesthetic, using –

• a volatile agent (avoid sevoflurane → the production of fluoride and compound A have been implicated in renal toxicity),
• a short acting opioid (consider using opioids without active metabolites that depend on renal excretion), and
• a muscle relaxant (mivacurium, atracurium, cisatracurium do not depend on renal excretion) in order to provide optimal operating conditions, while at the same time, maintaining hemodynamic stability and adequate end-organ perfusion.

Question 7

Could you utilize regional anesthesia for this case?

(A 42- year-old, 84 kg, man with an 8-year history of chronic renal failure is brought to the operating room for nephrectomy and cadaveric kidney transplantation harvested 16 hours ago. He has a functioning AV fistula in the left forearm and received dialysis 24 hours ago. The nurse states he is extremely anxious. Medications include nifedipine, lisinopril, ranitidine, and OTC antacids. Vital Signs: P = 95, BP = 195/115 mmHg, RR = 22, T = 37 °C)

Answer 7

Yes.

In the case of a difficult airway or strong patient preference, and assuming there were no contraindications, I would consider utilizing regional anesthesia.

In preparing for regional anesthesia, I would –

• inform the patient of potential complications;
• ensure adequate hydration;
• prepare to address any acute hypotension;
• obtain coagulation studies (specifically a PTT); and
• look for signs of coagulopathy such as marked or easy bruising, bleeding at the IV sight, and/or mucosal bleeding (CRF patients may have platelet dysfunction that results in abnormal coagulation despite normal coagulation studies).

In performing the procedure, I would take precautions to avoid vascular trauma (i.e. single pass, injection of local or saline through epidural needle prior to placing the catheter) and slowly raise the block to avoid rapid sympathectomy.

Finally, I would develop a plan to convert to general anesthesia should regional anesthesia prove insufficient.