General: Renal Transplantation
Stem 2
A 55-year-old female is scheduled for a cadaveric kidney transplant harvested 16 hours ago. She underwent dialysis 25 hours ago. She has a history of diabetes mellitus, hypertension, and coronary artery disease. Medications include glipizide, metoprolol, and alprazolam. Vital signs are HR 75, BP 180/90 mm Hg, RR 24, RA saturation 97%. Hb = 11.3 g/dL, platelets = 235 K, WBC = 10.1 K/mcL, Na = 140 mEq/L, K = 5.2 mEq/L.
A. Preoperative Evaluation
Evaluation
Question 1
What are the systemic manifestations of chronic renal failure?
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Answer 1
Chronic renal failure has effects on multiple organ systems:
Cardiac—patients are at risk for hypertension (HTN), congestive heart failure (CHF), cardiomyopathy, coronary artery disease (CAD), and hyperdynamic circulation.
Pulmonary—patients may have pulmonary edema.
GI—gastroparesis, gastritis, and pancreatitis
Hematological—anemia, coagulopathy, metabolic acidosis, hyperkalemia, hyperphosphatemia, hypocalcemia, and hyperuricemia
Neurological—encephalopathy, peripheral neuropathy, seizures, myoclonus, and asterixis
Question 2
What hematological issues are you concerned about in this patient?
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Answer 2
In addition to a baseline chronic anemia, I am concerned that this patient may have a coagulopathy because many patients with chronic renal failure (CRF) have thrombocytopathy and decreased prothrombin levels.
Question 3
Would you order any additional preoperative tests in this patient?
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Answer 3
Yes. I would want an EKG, a chest radiograph, coagulation profile, and tests for liver function enzymes, bilirubin, and albumin.
Hyperkalemia
Question 4
Would you delay the case to correct this patient’s serum potassium level?
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Answer 4
No. Chronic hyperkalemia secondary to renal failure is an expected finding with this patient. As long as she was not symptomatic, I would not delay the case. I would have medications such as calcium, insulin, glucose, bicarbonate, and a beta agonist in the operating room before induction, however.
Question 5
What if the patient’s repeat serum potassium comes back at 6.0 mEq/L? Would you delay the case then?
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Answer 5
Yes. At 6.0 mEq/L the serum K+ level is at a life-threatening level and can lead to ventricular fibrillation and asystole. I would delay the case and immediately begin treatment with calcium, insulin, bicarbonate, beta agonists, and glucose.
Question 6
The surgeon says that is a normal laboratory finding in a patient with renal failure and this is an emergency procedure. How would you respond?
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Answer 6
I would inform the surgeon of two things:
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- Renal transplants are not emergent cases. Cadaveric kidneys can be maintained for 36–48 hours to optimize the patient, and preoperative optimization will ensure a better outcome for the patient.
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- While some patients with end-stage renal disease (ESRD) do suffer from chronic hyperkalemia, a value of 6.0 mEq/L can be lethal and thus cannot be considered a normal finding. At this level, the patient may develop a malignant cardiac rhythm at any time.
Medications
Question 7
The patient informs you that she did not take any of her medications this morning. How would you manage this patient’s home medication regimen before bringing her to the operating room?
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Answer 7
This patient is currently on glipizide for diabetes mellitus (DM), metoprolol for HTN, and alprazolam for presumed anxiety. I would hold her glipizide because oral hypoglycemics should not be administered since the patient will be NPO and hypoglycemia may result from its administration. Conversely, I would continue her metoprolol because any patient on long-term beta-blocker therapy should continue it to reduce the risk of morbidity and mortality during such procedures. Finally, I would ask the patient to take her normal dose alprazolam so that she doesn’t have any symptoms of withdrawal or anxiety before arriving to the OR. Additionally, if she does appear anxious, I could titrate in a low dose of Midazolam before bringing her to the OR.
Premedication
Question 8
Would you administer any premedications to this patient?
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Answer 8
It depends. If this patient appeared anxious, I would begin with verbal reassurance. If she continued to be anxious, I would consider administering a low dose of midazolam. Next, because this patient is at risk for gastroparesis, I would administer sodium citrate as well as promotility agents such as metoclopromide, which will promote gastric emptying.
B. Intraoperative Management
Regional vs. General Anesthesia Techniques
Question 1
Could you do this case under regional?
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Answer 1
No. this patient likely has a coagulopathy secondary to uricemia leading to decreased von Willebrand factor (vWF) levels. Thus, I would want to avoid neuraxial techniques completely.
Monitors
Question 2
How would you monitor this patient?
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Answer 2
I would place the standard ASA monitors, a neuromuscular blockade monitor, preinduction arterial line, and a central line to optimize intravascular volume and follow CVP trends.
Induction
Question 3
How would you induce this patient?
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Answer 3
Assuming the patient has a reassuring airway, I would preoxygenate with 100% O2 and perform rapid sequence induction with fentanyl, etomidate, and succinylcholine. I would perform rapid sequence induction technique to reduce the risk of aspiration in this patient, who likely has gastroparesis secondary to chronic renal insufficiency.
Maintenance
Question 4
Assuming you decided to do this case under general anesthesia, what agents would you use for maintenance?
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Answer 4
I would use a balanced anesthetic technique with a volatile anesthetic, an opioid, and a muscle relaxant. In terms of inhalation agent, I would use Desflurane because it does not have nephrotoxic potential and has a rapid wash-in and washout time. I would avoid sevoflurane because its metabolism can produce nephrotoxic agents such as compound A and fluoride. Opioids can be used to maintain analgesia, although I would avoid meperidine and morphine because both depend on renal clearance and have active metabolites that can accumulate (morphine-3-glucuronide and morphine-6-glucuronide and normeperidine, respectively). Morphine-6-glucuronide accumulation can lead to worsening of respiratory depression. Normeperidine accumulation can lead to neurotoxic effects such as seizure activity. Finally, for neuromuscular blockade I would use cis-atracurium since metabolism and elimination are independent of the renal pathway.
Preparation for Graft Attachment
Question 5
The surgeon informs you that he is about to clamp the iliac vessels. What medications would you administer at this time?
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Answer 5
I would administer heparin before clamping (to prevent clotting) and have the surgeon inject verapamil or papaverine into the graft arteries before revascularization (to prevent arterial vasopasm) and mannitol/furosemide after graft reperfusion (to induce diuresis).
Renal Graft Reperfusion
Question 6
The kidney graft vessels and ureter are anastomosed and the clamp is now removed. The patient’s blood pressure quickly plummets to 77/38 mmHg. How do you respond?
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Answer 6
I would immediately check the patient’s other vital signs, including heart rate, pulse, end-tidal CO2, and oxygen saturation, and an EKG for any malignant arrhythmia. Hypotension immediately following unclamping is most likely due to the washout of vasoactive substances from the renal graft. Treatment would be primarily supportive. Thus, assuming all other vital signs were stable, I would open fluids wide, administer pressors such as phenylephrine or ephedrine, and send for an ABG with electrolytes.
Question 7
The EKG monitor shows peaked T waves. What is your response?
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Answer 7
This is most likely due to hyperkalemia from the preservative fluid of the new kidney. Thus, I would administer calcium gluconate for myocardial protection and then administer insulin, glucose, bicarbonate, and a beta agonist to decrease the serum levels of K+.
C. Postoperative Management
Extubation
Question 1
Would you extubate this patient?
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Answer 1
It depends on the clinical course. If the patient demonstrated hemodynamic stability with stable vital signs, was awake and alert, followed commands, was pulling in adequate tidal volumes (>6 mL/kg), and was full reversed and the operation was devoid of large fluid shifts, I would extubate. However, if the patient developed some unforeseen intraoperative event or had massive fluid shifts and was not able to breathe on her own, I would prefer to leave the patient intubated overnight.
Postoperative Oliguria
Question 2
You are paged stat to the PACU for decreased urine output. What is your differential?
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Answer 2
Oliguria can be categorized as prerenal, intrarenal, and postrenal. Prerenal oliguria is due to hypoperfusion, which is usually caused by hypovolemia. Thus, I would check input and outputs (I/Os) to assess how much fluid the patient has been given, check CVP readings if there is a central line, and send for electrolytes to assess for signs of dehydration such as hypernatremia. I would also look at her skin turgor and mucus membranes. Postrenal pathology is usually due to a kinked Foley catheter or bladder obstruction. Intrarenal oliguria is often due to the presence of nephrotoxic substances. A urinalysis with casts would be helpful in confirming the diagnosis. Additionally, this patient maybe experiencing graft rejection, toxic injury, or vessel occlusion.
Question 3
What are some laboratory differences between prerenal and renal oliguria?
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Answer 3
Common indices to differentiate prerenal and renal oliguria include urine osmolality, urine sodium, fractional excretion of sodium (FENa), and urine:serum creatinine ratio. Urine osmolarity (mOsm/L) is greater than 500 in patients with prerenal etiology and less than 400 in patients with renal etiology. Urine sodium is less than 20 mEq/L in prerenal patients and greater than 40 mEq/L in patients with renal etiology. The urine:serum creatinine ratio is greater than 40 in prerenal etiology patients and less than 20 in patients with renal etiology. The blood urea nitrogen (BUN)/creatinine (Crt) ratio in prerenal etiology patients is greater than 20 and often less than 10–15 in renal etiology patients. FENa, measured as a percentage, is less than 1% in prerenal patients and greater than 2% in renal patients.
Nausea
Question 4
You are paged from the postoperative care unit because the patient is complaining of nausea. How will you respond?
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Answer 4
Nausea here has several possible etiologies. My first response would be to rule out hypoxia, hypoventilation, and hypotension. I would also evaluate for anxiety, postoperative pain, and opioid side effect. Assuming all of this was normal, I would administer a dose of a 5-HT3 blocker, such as Zofran.