UBP 6.8 (Long Form): Renal – Arterial Venous Fistula

Question 1

Intra-operative Management:

What is your plan for anesthesia?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 1

Since this procedure may be performed utilizing general anesthesia, an upper extremity regional block, or with local anesthesia and sedation, my choice of anesthetic technique would depend on – the location of surgery, the anticipated length of surgery, the patient’s coagulation status, associated medical conditions, as well as patient and surgeon preference.

Assuming there were no contraindications, such as a coagulopathy (i.e. residual heparin effect, platelet dysfunction), my preference would be to provide regional anesthesia using an axillary block (for surgery below the elbow) or an interscalene block (for surgery proximal to the elbow).

Regional anesthesia has the advantage of providing adequate analgesia and good post-operative pain control, potentially reducing the number of deleterious drug effects (i.e. avoiding the administration of multiple drugs with altered pharmacokinetics and pharmacodynamics), facilitating the introduction of cannulas via peripheral vasodilation, and avoiding the need for intubation and mechanical ventilation of a patient at increased risk of aspiration (history of GERD and the reduced gastric motility, nausea and vomiting, and hypersecretion of gastric acid associated with CRF).

Due to the increased risk of myocardial irritability (i.e. acidosis, hyperkalemia, and volume overload), I would avoid local anesthetic solutions containing epinephrine or use them with caution (consider using a 1:400,000 concentration).

Question 2

Intra-operative Management:

You place an interscalene block. Following incision, the patient says he feels everything.

What would you do?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 2

Ideally, I would have verified the adequacy of the regional block prior to incision.

At this point, however, I would have the surgeon stop;

assess the quality and location of the patient’s pain (interscalene blocks are associated with ulnar nerve sparing);

consider a small (50 mg) intravenous dose of ketamine (???) ; and

supplement the block with local infiltration as indicated by my exam, while being careful to avoid local anesthetic toxicity.

If these measures were inadequate, I would prepare to convert to a general anesthetic.

Question 3

Intra-operative Management:

The patient is not tolerating regional anesthesia. How will you induce general anesthesia?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 3

My goals in inducing this patient with diabetes, GERD, and CRF, who is at increased risk of –

hypotension (autonomic neuropathy, uncertain volume status, and an exaggerated response to induction agents),

gastric aspiration (history of GERD, reduced gastric motility, nausea and vomiting, and hypersecretion of gastric acid associated with CRF), and

difficult airway management (i.e. diabetic stiff joint syndrome), are –

to rapidly and safely secure his airway, while avoiding aspiration, hyperkalemia, or hypotension.

Therefore, assuming he was hemodynamically stable, his airway exam was reassuring, and that there were no signs of diabetic stiff joint syndrome (“prayer sign”), I would pre-oxygenate him with 100% oxygen, place him in a slight trendelenburg position (to reduce the risk of passive aspiration), apply cricoid pressure, and perform a rapid sequence induction.

Considering his treatment with an ACE inhibitor and recognizing that CRF patients often become hypotensive during induction (despite their volume status), I would use etomidate to reduce the risk of peripheral vasodilation and myocardial depression.

In order to avoid a dangerous increase in serum potassium in a patient who already has a potassium level of 5.5 mEq/L, I would use rocuronium (0.9-1.2 mg/kg) rather than succinylcholine to rapidly achieve optimum intubating conditions (succinylcholine can result in a 0.5-1.0 mEq/L increase in serum potassium).

When intubating conditions were satisfactory, I would perform careful laryngoscopy, insert a properly sized endotracheal tube, auscultate the lungs to verify proper placement, and then release cricoid pressure.

Question 4

Intra-operative Management:

While you are securing the endotracheal tube, the resident pushes meperidine and turns on the sevoflurane. Are these good choices for maintenance of anesthesia?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 4

Given the potential CNS toxicity associated with the accumulation of meperidine’s renally excreted metabolite, normeperidine, I would avoid the administration of this opioid.

When using a narcotic for a patient with CRF, I would prefer to use fentanyl, who’s pharmacokinetics are less affected by ESRD due to a lack of active metabolites, an unchanged free fraction, and a short redistribution phase.

Likewise, Sevoflurane would not be my first choice for inhalational anesthetic since the metabolism of this agent may produce compound A (nephrotoxic in rats) and nephrotoxic levels of inorganic fluoride (>50 umol/L).

For these reasons, when considering a volatile agent for maintenance of anesthesia, I would prefer to use isoflurane or desflurane.

Question 5

Intra-operative Management:

How does chronic renal failure alter the pharmacological effects of intravenous anesthetics?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 5

The physiologic changes associated with CRF have a variable effect on the pharmacokinetics and pharmacodynamics of intravenous drugs.

Drugs that are highly dependent on renal excretion for clearance of the parent compound or active metabolites may have an increased duration of action.

On the other hand, drugs that do not have active metabolites, and whose termination of action is dependent on redistribution and metabolism, may exhibit a normal duration of action.

It is important to recognize, however, that an increased volume of distribution (commonly associated with CRF) and/or altered hepatic metabolism (some hepatic enzymes are inhibited and others are induced in the setting of CRF) may affect the duration of action of this latter group as well.

Moreover, decreased protein binding (reduced binding of acidic drugs results in greater fraction of pharmacologically active drug), uremic-induced disruption of the blood-brain barrier (resulting in greater brain penetration), and a synergistic effect with various renally excreted toxins, often results in increased sensitivity to many intravenous anesthetics.

Question 6

Intra-operative Management:

Following induction, the patient’s blood pressure decreases to 83/50 mmHg. What do you think is going on?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 6

There are several potential causes of his decrease in blood pressure.

The timing of the event, the often increased sensitivity of CRF patients to intravenous anesthetics, and the cardiovascular lability often associated with HTN, suggests the most likely cause to be the cardiovascular effect of the induction agent with or without hypovolemia.

However, I would also be considering:

1. myocardial ischemia, since peripheral vascular disease is often associated with coronary artery disease;
2. a hyperkalemia-induced dysrhythmia, since the patient’s potassium is elevated (especially if succinylcholine were used during induction);
3. cardiac tamponade, since CRF and inadequate dialysis can lead to pericarditis and pericardial effusion;
4. hypovolemia, secondary to overaggressive dialysis;
5. autonomic neuropathy, a condition associated with both diabetes mellitus and CRF;
6. the perioperative continuation of his ACE inhibitor (associated with significant perioperative hypotension);
7. tension pneumothorax, a risk assocaited with the placement of an interscalene block; and
8. allergic reaction (especially if antibiotics were administered).

Question 7

Intra-operative Management:

Upon examination, you note jugular venous distension and muffled heart sounds.

What are you going to do?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 7

The clinical picture of hypotension, jugular venous distension, and muffled heart sounds are consistent with cardiac tamponade,

a condition that may develop when uremic pericarditis leads to pericardial effusion.

Therefore, I would –

• alert the surgical team,
• deliver 100% oxygen,
• discontinue any anesthetic drugs that may be contributing to cardiac depression,
• administer fluids for volume expansion,
• consider the administration of catecholamines,
• treat any bradycardia (i.e. atropine),
• request transesophageal echocardiography to confirm the diagnosis, and
• correct any significant electrolyte abnormalities or metabolic acidosis (which can contribute to cardiac depression).

While dialysis could help to resolve a pericardial effusion, this hemodynamically unstable patient may require immediate pericardiocentesis or pericardiotomy to relieve cardiac compression.

Question 8

Post-operative Management:

After surgery, peripheral nerve stimulation reveals fade with a train of four and un-sustained tetany despite a full reversal dose of Neostigmine.

What do you think is the cause?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 8

If residual neuromuscular blockade were present despite the administration of a maximal dose of neostigmine (0.07 mg/kg), my differential would include –

• medication error,
• excessively profound neuromuscular blockade at the time of anticholinesterase administration (it is recommended to delay reversal until 25% recovery of neuromuscular function is indicated by the appearance of the 4th twitch with train-of-four stimulation), and
• factors that are known to interfere with neuromuscular blockade reversal.

This patient is taking an aminoglycoside antibiotic, which has been shown to potentiate nondepolarizing neuromuscular blocking drugs, sometimes making it difficult to achieve adequate reversal of blockade.

Other factors that may interfere with antagonism include –

• hypokalemia,
• hypocalcemia,
• hypermagnesemia,
• impaired renal excretion of the active neuromuscular blocking drug,
• metabolic and respiratory acidosis,
• calcium channel blockers, and
• hypothermia.

Question 9

Post-operative Management:

Would you administer an additional dose of Neostigmine?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 9

If the maximum dose of neostigmine (70 mcg/kg) had been given, I would not administer additional neostigmine.

Not only is there a ceiling effect for all anticholinesterase agents (neostigmine = 0.07 mg/kg; edrophonium = 1.0 mg/kg), where additional drug provides no further antagonism, but excessive doses of anticholinesterase may result in a paradoxical potentiation of nondepolarizing neuromuscular blockade.

This paradoxical effect may be explained by the fact that excessive amounts of acetylcholine first stimulate, and then depress, the nicotinic receptors in the neuromuscular junction (weakness is one of the symptoms of cholinergic crisis).

Question 10

Post-operative Management:

Would you administer a different anticholinesterase, like edrophonium?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 10

Recognizing that the mixing or combining of anticholinesterases does not lead to potentiated (and possibly not even additive) effects,

I would NOT administer another antagonist.

Instead, I would verify that the intravenous catheter is functioning properly, rule out a medication error, and ensure the maximal dose of the initial reversal agent was administered.

Question 11

Post-operative Management:

After the patient is extubated the PACU nurse calls and says the patient is complaining of shortness of breath.

What do you think may be going on?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 11

Given the patient’s intra-operative course and medical history, I would give special consideration to –

• pulmonary aspiration (GERD),
• recurrent cardiac tamponade (intra-operative cardiac tamponade),
• pneumothorax (interscalene block),
• ispilateral diaphragmatic paresis due to phrenic nerve blockade (interscalene block),
• dysrhythmia (HTN, hyperkalemia, and hypocalcemia),
• cerebral edema (hyponatremia),
• pulmonary edema (low-pressure pulmonary edema may occur with ESRD due to increased permeability of alveolar capillary membranes, characterized radiologically by a “butterfly wing” distribution of fluid),
• myocardial ischemia (high association of CAD with ESRD),
• congestive heart failure (cardiac tamponade, HTN, volume overload, myocardial ischemia), and
• residual neuromuscular blockade.

However, I would also consider –

• atelectasis (inadequate intra-operative tidal volumes, pain, etc.),
• bronchospasm,
• upper airway obstruction,
• inadequate pain control, and
• pulmonary embolism.

Question 12

Post-operative Management:

Could his shortness of breath be due to the interscalene block he received?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 12

Yes.

As I mentioned, complications associated with the placement of an interscalene block include – pneumothorax and ipsilateral diaphragmatic paresis (phrenic nerve blockade), either of which could cause shortness of breath.

While ipsilateral diaphragmatic paresis is usually well tolerated, it may result in respiratory distress when concomitant with preexisting lung disease, residual neuromuscular blockade, or narcotic-induced respiratory depression.

An inspiratory chest x-ray can help to diagnose phrenic nerve blockade and rule out a more serious complication, such as pneumothorax.

Question 13

Post-operative Management:

What are your criteria for discharge from same day surgery?

• (A 72-year-old, 78 kg, male presents for AV fistula revision. He has a 6-year history of renal failure, requiring hemodialysis for the last 4 years. His last dialysis session was performed twelve hours ago via a subclavian line.*
• PMHx: HTN, Peripheral vascular disease, GERD, Type II DM*
• Meds: Lisinopril, ASA, Metformin, Nexium, Gentamicin, and a MVI*
• Allergies: NKDA*
• PE: Vital Signs: HR = 94, BP = 162/89 mmHg, RR = 20, Temp = 37.6 C*
• Airway: MP II, TMD > 60 cm, full cervical range of motion*
• Lungs: CTAB*
• CV: RRR*
• EKG: Left ventricular hypertrophy*
• Labs: Hgb = 10.2 gm/dL, Na+ = 130 mEq/L, K+ = 5.5 mEq/L)*

Answer 13

My decision to discharge patients from ambulatory surgery would be based on the post-anesthetic discharge scoring system (PADSS).

This system is based on five major criteria:

1. vital signs, including BP, HR, RR, and Temperature;
2. ambulation and mental status;
3. pain and PONV;
4. surgical bleeding; and
5. fluid intake/output.

Patient who achieve a score of 9 or greater, and have an adult escort, are considered fit for discharge.

The requirement for patients to drink and void before discharge is no longer considered mandatory.