UBP 6.6 (Long Form): CV – Femoropopliteal Bypass Flashcards
Secondary Subject -- Perioperative ACE Inhibitor / Acute Renal Failure / Protamine Reaction / Chronic Renal Failure / Cardiac Conduction Disorders / Contrast-Induced Nephropathy / Coronary Artery Disease / Coronary Revascularization / Diabetes / Fenoldopam / Hypertension / Mechanical Ventilation / Neuraxial Anesthesia in the Coagulopathic Patient / Peripheral Vascular Disease / Pulmonary Artery Catheterization
Intra-operative Management:
The patient is anxious about undergoing general anesthesia and is requesting an epidural anesthetic for this surgery.
Would you agree?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields*)
Assuming the patient had discontinued his thienopyridine antiplatelet therapy for an appropriate interval (7 days for clopidogrel and 14 days for Ticlopidine), and that there were no other contraindications,
I would consider placing an epidural for this case.
In making this decision, I would be considering –
- patient preference,
- the length of the procedure (which may affect patient comfort), t
- he patient’s ability to cooperate and lie supine for a prolonged period of time, and
- the risks associated with neuraxial anesthesia, such as –
- sympathectomy-induced hypotension,
- epidural/spinal hematoma (especially in the anticoagulated patient),
- epidural/spinal abscess,
- headache, and
- meningitis.
There is some evidence that regional anesthesia may –
- improve graft survival
- (due to sympathectomy-induced improvement of lower extremity blood flow and attenuation of the postoperative hypercoagulable state often associated with general anesthesia),
- reduce the number of postoperative respiratory and infectious complications
- (due to improved pain control and respiratory function), and
- decrease the incidence of myocardial ischemia/infarction
- (due to sympathectomy-induced reductions in preload and afterload, and to the avoidance of the hyperdynamic response associated with intubation and/or extubation).
** However, this evidence is limited, and any overall reduction in morbidity and mortality is probably very small, especially when general anesthesia is combined with good hemodynamic control (i.e. heart rate and perfusion pressure), adequate postoperative pain control, incentive spirometry and chest physiotherapy, and pharmacologic anticoagulation as necessary.
Moreover, general anesthesia may provide better patient comfort for long procedures, obviate the need for good patient cooperation, and provide beneficial cardiac preconditioning with the use of inhalational agents.
If, however, I decided to proceed with neuraxial anesthesia, I would rule out any current coagulopathy (especially since he will likely require systemic heparinization), delay systemic heparinization for 60 minutes following placement, minimize heparin dosing, and plan to remove the epidural catheter only after the complete restoration of normal coagulation.
Intra-operative Management:
What are the ASRA guidelines concerning neuraxial anesthesia and plavix administration?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
Due to the increased risk for developing an epidural or spinal hematoma when taking thienopyridine derivates, the ASRA guidelines recommend delaying neuraxial anesthetic placement for 7 days after discontinuation of clopidogrel (Plavix).
Therefore, neuraxial anesthesia would not have been a good option for this patient unless it was determined that he had stopped his medication at least 7 days prior.
- Clinical Note:*
- See Table of “Recommendations for Neuraxial Anesthesia in the Anticoagulated Patient” (p. 121-122 of Practice Set #6)
Intra-operative Management:
You decide to place an epidural catheter, but note bleeding through the epidural needle after entering the epidural space.
Do you need to delay surgery?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
Although some practitioners have advised delaying surgery for 24 hours following a traumatic neuraxial block,
the evidence is insufficient to support this recommendation.
Therefore, recognizing that heparinization for vascular surgery usually involves an intravenous injection of only 5,000-10,000 U of heparin,
I would make the surgeon aware of the increased risk of epidural or spinal hematoma associated with systemic heparinization immediately following traumatic neuraxial needle instrumentation, and make a decision based on a careful weighing of risks and benefits.
However, if this patient were undergoing complete heparinization, as occurs during coronary artery bypass (CABG) surgery, I would recommend delaying the procedure for 24 hours to avoid exposing the patient to an unacceptably high risk of developing an epidural or spinal hematoma.
Intra-operative Management:
The patient refuses further attempts at epidural catheter placement, and states that he wants to be put to sleep for the case.
What monitors would you place?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
Given this patient’s hypertension, coronary artery disease, renal insufficiency, and peripheral vascular disease, the special monitoring I would employ would include:
- an intra-arterial catheter,
- to provide access for frequent blood draws and facilitate the maintenance of optimal perfusion pressures to the heart, brain, kidneys, and lower extremity;
- a central venous catheter
- to monitor cardiac function, provide access for a pulmonary artery catheter should it be required, and facilitate fluid management; and
- a Foley urinary catheter,
- to monitor urine output and facilitate intravascular volume management during this potentially prolonged procedure.
Intra-operative Management:
Considering his significant coronary artery disease, would you consider using computerized ST-segment analysis during the case?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
While continuous ST-segment analysis would be desirable in monitoring many patients at risk for myocardial ischemia,
its use is limited in those with certain underlying electrocardiographic abnormalities.
Therefore, I would NOT use it for this case, recognizing that the patient’s left bundle branch block may interfere with accurate ST-segment analysis.
Other baseline electrocardiographic abnormalities that would hinder accurate computerized ST-segment analysis include –
- Wolff-Parkinson-White syndrome,
- acute pericarditis,
- left ventricular hypertrophy with strain,
- digitalis effect, and
- hypokalemia.
Intra-operative Management:
The surgeon is requesting a pulmonary artery catheter, because he wishes to utilize it for postoperative care. Would you agree to this?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
While I do not believe a pulmonary artery catheter is absolutely necessary for this case,
I would agree to preoperative placement if the surgeon required the monitor for postoperative management.
However, I recognize that the insertion of a pulmonary artery catheter induces transient right bundle branch block in 2-5% of patients, placing this patient with left bundle branch block at risk for complete heart block.
Therefore, I would make sure that transcutaneous pacing was immediately available during the procedure.
Intra-operative Management:
How would you induce this patient?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
Given this patient’s poorly controlled hypertension, coronary artery disease, peripheral vascular disease, and diabetes mellitus,
I would be concerned that –
- hypotension (increased risk due to the intravascular volume contraction associated with chronic hypertension and, possibly, diabetes induced autonomic neuropathy),
- hypertension, and/or
- tachycardia,
- occurring during induction and laryngoscopy could lead to – myocardial ischemia or infarction.
Therefore, I would:
- ensure the availability of B-blockers and vasoactive agents;
- administer an opioid and intravenous lidocaine to attenuate the hyperdynamic response to laryngoscopy; and
- perform a controlled induction utilizing etomidate, nitrous oxide, and a volatile agent, with the goals of avoiding hypotension, while at the same time achieving a depth of anesthesia adequate to prevent a hyperdynamic response to laryngoscopy.
Intra-operative Management:
Immediately after intubation the patient’s blood pressure falls to 68/44 and his heart rate is 51 bpm.
What do you think is the cause?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
There are several potential causes of the decrease in blood pressure experienced by this B-blocked patient following induction.
My differential would include the following causes and contributory factors:
- the cardiovascular lability often associated with chronic hypertension and/or diabetic autonomic neuropathy;
- myocardial ischemia or infarction
- (possibly secondary to hypotension, hypertension, tachycardia, arrhythmia, or coronary thrombosis);
- arrhythmia
- (possibly secondary to myocardial ischemia or infarction in this patient who already has left bundle branch block);
- excessive anesthesia;
- the perioperative continuation of his ACE inhibitor
- (associated with significant perioperative hypotension);
- autonomic neuropathy, a condition found in 50% diabetic patients with hypertension
- (predisposes patient to cardiovascular instability and an inability to adequately compensate for hemodynamic changes);
- tension pneumothorax, secondary to central line placement; and
- allergic reaction.
Intra-operative Management:
After completion of the bypass, the surgeon wants to perform an intraoperative angiogram using contrast dye.
Does this concern you?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
I am concerned due to the potential for adverse reactions associated with the use of contrast media resulting from direct toxicity, idiosyncratic reactions, and/or allergic reactions (anaphylactic or anaphylactoid).
In particular, I am concerned about the potential for contrast-induced nephropathy developing in this patient who is at increased risk due to –
- his renal insufficiency,
- diabetes mellitus,
- hypertension, and likely
- hypovolemia secondary to poorly controlled chronic hypertension
- (other risk factors for contrast-induced nephropathy include –
- age,
- anemia,
- hypoalbuminemia,
- multiple myeloma,
- congestive heart failure,
- renal transplant, and
- the use of high dose, high osmolar, high viscosity, and/or ionized agents).
Therefore, I would take the following steps to reduce his risk:
- ensure adequate hydration with normal saline
- (infusion of 1 mL/kg should be started at least 4 hours before surgery and continued for 12 hours following dye administration),
- ask the surgeon to utilize an agent that is non-ionic, low or iso-osmolar, and low in viscosity
- (there is some evidence to suggest this lowers risk, especially in high risk patients);
- initiate an infusion of sodium bicarbonate to alkalinize the urine
- (start infusing 3 mL/kg/hr for 1 hour before injection and continue at 1 mL/kg/hr for the next 6 hours; works by reducing the production of free radicals); and
- administer an antioxidant, such as
- N-acetylcysteine (mucomyst) or
- ascorbic acid (the administration of N-acetylcysteine is not universally recommended due to insufficient evidence and risk of anaphylactoid reactions).
- While mannitol has been utilized to prevent contrast-induced nephropathy, it may actually exacerbate renal injury secondary to osmotic-induced dehydration.
Clinical Note:
- Since most reactions are non-immune mediated, prophylactic treatment with histamine antagonists and corticosteroids may be beneficial in patients with a known allergy to contrast media
- (i.e. administer 50 mg prednisone at 13, 7, and 1 hour prior to injection of contrast dye, also administer 50 mg of diphenhydramine 1 hour prior to dye injection).
Intra-operative Management:
Would you administer fenoldopam for renal protection?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
While the selective dopaminergic-1 agonist, fenoldopam, may reduce the incidence of acute postoperative renal failure in patients undergoing major vascular surgery and/or receiving radiocontrast dye, the evidence is conflicting.
Therefore, I would NOT administer this drug UNLESS I was also attempting to lower his blood pressure.
Fenoldopam reliably causes systemic vasodilation in a dose-dependent manner (unlike dopamine, which may exhibit a 30-fold variability in pharmacokinetic effect), while preserving or augmenting renal blood flow.
This renal protective effect, in conjunction with a rapid onset (5 minutes) and relatively fast metabolism, make it a good drug for treating severe blood pressures in patients with renal insufficiency.
Intra-operative Management:
Following successful bypass and heparin reversal, the surgeon is closing the incision when the patient’s blood pressure drops to 70/48.
What is your differential diagnosis?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
Considering that this patient developed hypotension following the administration of protamine for heparin reversal, the most likely cause of his hypotension is
- histamine release with the rapid administration of protamine, with or without concomitant hypovolemia (administration over 5-10 minutes is recommended to reduce the incidence of this pharmacologic side effect).
- However, I would also be considering other potential causes and contributory factors, such as:
- anaphylactic or anaphylactoid reaction to contrast dye or protamine;
- protamine-induced catastrophic pulmonary hypertension with subsequent heart failure (The use of neutral protamine Hagedorn insulin – NPH insulin – is an independent risk factor for protamine hypersensitivity reaction.
- However, this type of reaction is dose dependent, and is probably less likely given the reduced dose of protamine required for heparin reversal in peripheral vascular surgery, as compared to cardiopulmonary bypass.);
- excessive anesthesia;
- myocardial ischemia or infarction;
- arrhythmia;
- continuation of his ACE inhibitor;
- autonomic neuropathy;
- anemia;
- hypovolemia; and
- tension pneumothorax.
Intra-operative Management:
Can you describe the different types of adverse protamine reactions?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
Adverse protamine reactions can be classified into three types of reactions.
-
Type I reactions (pharmacologic) are characterized by –
- histamine-induced venodilation,
- decreased systemic vascular resistance, and
- reduced preload.
-
Type II reactions (immunologic) are further broken up into 3 subcategories, with –
- Type IIA reactions representing anaphylactic reactions (antibody-mediated),
- Type IIB reactions representing an immediate anaphylactoid reaction (not antibody-mediated), and
- Type IIC reactions representing a delayed anaphylactoid response that results in noncardiogenic pulmonary edema.
-
Type III reactions are characterized by –
- catastrophic pulmonary hypertension that leads to right heart failure and significant hypotension
- (pulmonary hypertension may be caused by the protamine-heparin complex-induced release of thromboxane A2 in the pulmonary circulation).
Type I reactions are considered to be predictable pharmacologic reactions, whereas Type II and Type III reactions are considered to be idiosyncratic reactions (i.e. reactions that occur rarely and unpredictably).
Intra-operative Management:
Assuming this were a protamine reaction, what would you do?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
If this were a protamine reaction, I would avoid any additional protamine administration and check the patient’s pulmonary artery pressure.
If his pulmonary artery pressure were low or normal, this would be consistent with a pharmacologic reaction (histamine-induced hypotension secondary to rapid administration), anaphylaxis, or an anaphylactoid reaction, and I would begin with –
the administration of fluids and vasoconstrictors.
If the patient did not respond adequately or developed signs consistent with an anaphylactic or anaphylactoid reaction (i.e. urticarial, facial edema, bronchospasm, pulmonary edema, etc.), I would –
administer epinephrine, an inhaled B2-agonist, corticosteroids, and an antihistamine.
A Type III reaction is less likely in this case due to the reduced dose of protamine utilized for heparin reversal in peripheral vascular surgery (this type of reaction is dose dependent), as compared to cardiopulmonary bypass.
However, if his pulmonary artery pressures were high and/or there were signs of right heart failure, I would –
administer epinephrine and/or an inotrope with vasodilating properties (i.e. milrinone, amrinone, or isoproterenol); and consider providing nitric oxide, if necessary.
If the patient was hemodynamically stable, but did not respond adequately following the administration of inotropes, I would try –
administering a low dose of heparin (70U/kg), with the hopes that this would break up large heparin-protamine complexes and thereby reduce the production of thromboxane A2.
If the patient remained unstable or did not respond to the low dose heparin, I would –
talk to the surgeon about full heparinization and the institution of cardiopulmonary bypass.
Post-operative Management:
Following surgery the patient is stabilized, remains intubated, and is being transported to the ICU.
What are your primary post-operative concerns for this patient?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
I have a number of concerns for this patient postoperatively, including:
- myocardial ischemia or infarction,
- recognizing that cardiac morbidity and mortality is highest in the postoperative period;
- renal failure,
- especially considering that this patient with preoperative renal insufficiency received contrast media;
- graft occlusion;
- blood pressure lability
- (secondary to his poorly controlled chronic hypertension, pain, and the stress response to surgery), which could lead to –
- myocardial ischemia, renal injury, or graft occlusion;
- (secondary to his poorly controlled chronic hypertension, pain, and the stress response to surgery), which could lead to –
- arrhythmias, which could compromise end-organ perfusion;
- hypo/hyperglycemia;
- inadequate pain control,
- which would increase the risk of hypertension and myocardial ischemia; and
- hypothermia,
- which is associated with an increased incidence of myocardial ischemia in the early postoperative period.
- Finally, if his protamine reaction had resulted in pulmonary hypertension, I would also be concerned about this leading to – right heart failure with subsequent myocardial ischemia/infarction.
Post-operative Management:
What can be done to minimize his postoperative complications?
- (A 63-year-old, 65 kg, male is scheduled for femoropopliteal bypass secondary to significant claudication. He underwent balloon angioplasty 5 weeks ago.*
- PMHx: HTN, IDDM, Renal insufficiency, Peripheral neuropathy, CAD s/p CABG 4 years ago, Smoker - one pack per day for 35 years*
- Medications: ASA, lantus, NPH insulin, lisinopril, and metoprolol*
- Allergies: PCN*
- PE: Vital Signs: HR = 89, BP = 158/92 mmHg, Temp = 38ºC*
- Airway: Dentures, Mallampati II, full cervical range of motion*
- Heart: RRR*
- Lungs: Mild expiratory wheezing*
- Extremities: hair loss and skin coolness noted in the right lower extremity*
- Labs: Hgb = 16 mg/dL, K = 4.5 mEq/L, Creatinine = 1.8 mg/dL, Creatinine Clearance = 40 mL/min, blood urea nitrogen = 53 mg/dL, Glucose = 140 mg/dL*
- ABG: pH = 7.37. PaO2 = 82, HCO3 = 23 mEq/L, PaCO2 = 42 mmHg*
- EKG: Left Bundle Branch Block*
- CXR: Hyperinflated lung fields)*
The steps that could be taken to minimize his post-operative complications include:
- employing full monitoring, to identify any hemodynamic changes, worsening pulmonary hypertension, and/or myocardial ischemic changes;
- providing adequate pain control;
- ensuring tight control of his heart rate and blood pressure;
- AVOIDing any –
- anemia (to maintain oxygen carrying capacity),
- hypothermia (to avoid increased myocardial oxygen consumption and peripheral vasoconstriction that may limit lower extremity graft outflow), or
- hypovolemia (to maintain cardiac preload and renal perfusion, and avoid peripheral vasoconstriction);
- continuing his B-blocker and statin therapy postoperatively;
- keeping his feet warm and checking his peripheral pulses hourly to verify lower extremity graft patency; and
- providing adequate ventilation to optimize oxygenation (and avoid increased pulmonary hypertension if he experienced a Type III reaction).
- Again, if his protamine reaction were a Type III reaction, I would – continue to treat his pulmonary hypertension and support right heart function as necessary.
