Vascular Flashcards
Atherosclerosis
Stage I
Fatty streak
- Endothelium damaged d/t hemodynamic shear stress, oxidize LDL destruction, chronic inflammatory responses, infection, & hypercoagulability → thrombosis
- Lipoproteins enter the arterial intimal layer via endothelium, become entrapped, & promote inflammation
Atherosclerosis
Stage II
Fibrous plaque
- Oxidized lipid accumulation, inflammatory cells, proliferated smooth muscle cells, connective tissue fibers, & Ca2+ deposits
- Blood flow reduction → ischemia to vital organs & extremities → thrombus risk
Atherosclerosis
Stage III
Advanced lesion
- Plaque w/ expanded lipid-rich necrotic core, Ca2+ accumulation, endothelial dysfunction
- Physical disruption to plaque protective cap (ulceration rupture) exposes blood to highly thrombogenic material promoting acute thrombus formation & vasospasm
- Complete occlusion possible → MI, stroke, ischemia
Atherosclerosis Pathophysiology
Generalized, progressive, chronic inflammatory disorder
Fibrous intimal plaques associated w/ endothelial dysfunction develop in the arterial tree
Compromises blood flow to all organs & extremities lead to MI, stroke, & gangreneA
Atherosclerosis Types
- Enlarged plaque reduces blood vessel lumen (ischemia or stable angina) → supply vs. demand & delayed periop MI
- Plaque rupture/ulceration, embolization, & thrombus formation (unstable angina, MI, TIA/CVA) → acute occlusion & early periop MI
- Media atrophy w/ arterial wall weakening (aneurysm dilation)
What’s the most common site for atherosclerotic lesions?
42% aortoiliac peripheral 32% coronary 17% aortic arch branches 6% combined 3% mesenteric renal
What medications to continue prior to vascular surgery?
Aspirin - antiplatelet ↑bleeding ↓GFR Statins - check liver function Diuretics - hypovolemia & electrolyte imbalance Ca2+ channel blockers - HoTN β blockers - bronchospasm ↓HR ↓BP
What medications to discontinue prior to vascular surgery?
ACE inhibitors - HoTN w/ induction & coughing
Plavix (hold 7-8 days) antiplatelet ↑bleeding risk
Hypoglycemic drugs - hypoglycemia & lactic acidosis w/ Metformin
Bare Metal Stent
Do NOT stop antiplatelet therapy < 1mos
↑MI risk
Drug-Eluting Stent
Do NOT stop antiplatelet therapy < 6mos
What’s the critical period for coronary stents to endothelialize?
6 weeks
Recommendations to optimize patient prior to vascular surgery:
Smoking cessation
Weight loss & exercise
Culprit Lesions
Vulnerable plaques w/ high thrombotic complication likelihood
Often located in coronary vessels w/o critical stenosis
Demand Ischemia
Predominant cause periop MI
Supply/demand mismatch
What predicts long-term mortality associated w/ vascular surgery?
Preop renal insufficiency or chronic renal disease → postop failure
LE Peripheral Artery Disease
PAD or atherosclerotic occlusive LE disease
Insufficiency in LEs presenting w/ acute or chronic limb ischemia w/ occlusions distal to the inguinal ligament
LE Peripheral Artery Disease Revascularization Associated Risks
Amputation, stroke, MI, death
Diabetes ↑risk
Assume atherosclerosis present in other areas - cardiac or cerebrovascular
LE Peripheral Artery Disease
Revascularization Preop Considerations
Patients on antiplatelet & anticoagulants
- Ask when last taken
- Consult w/ surgical team about bleeding risk
- ASA, ticagrelor P2Y12 inhibitors, Rivaroxaban Xa inhibitor
- Clopidogrel 30% patients assumed pharmacogenetically resistant
Assess baseline S/S
β blockers & other chronic medications
Peripheral Revascularization Indications
Acute ischemia d/t emboli, thrombus, or pseudoaneurysm postop (femoral line)
Chronic ischemia d/t atherosclerotic plaque progressively narrowing the vessels - claudication w/ eventual vessel thrombosis
Acute Ischemia
Irreversible ischemia damage occurs w/in 4-6hrs
- Urgent thrombolytic therapy and/or angioplasty
- Arteriography
- Surgical intervention
Chronic Ischemia
Surgery indicated when severe disabling claudication & critical limb ischemia (limb salvage)
Peripheral Revascularization
Surgical Approach
Donor artery or vein w/ unobstructed blood flow exposed (common femoral, superficial femoral, or deep femoral) Target distal artery (recipient) exposed at or below the knee (dorsalis pedis or posterior tibial arteries) Tunnel created & graft passed Heparin IV (does not require reversal) Anastomosis constructed & arteriogram to conform adequate blood flow
Peripheral Revascularization
Monitoring
Continuous EKG monitoring w/ ST analysis A-line CVP or PA catheter Foley to monitor I/Os (intravascular volume) Minimal blood loss & 3rd spacing Regional or general approach
Peripheral Revascularization
Emergency Surgery Considerations
Monitor K+ levels Myoglobinemia Fasciotomy? Coagulation status EKG ischemia
Peripheral Revascularization
Regional vs. General
Assess coagulopathy or anticoagulation therapy
Spinal best to avoid hematoma
No difference b/w regional & general based on cardiopulmonary complications
Regional 5x superior to general r/t graft occlusion complication rates
Graft Occlusion
Significant w/ general anesthesia approach in postop period
Hypercoagulable state
↓fibrinolysis → fibrinogen not broken down & clots form
↑Epi/NE/cortisol
Graft patency maintained w/ regional 2° ↑blood flow w/ sympathectomy
Peripheral Revascularization
Anesthetic Management Intraop
AVOID vasopressors
Keep feet warm
Regional:
- L1 → L4 dermatomes
- T10 level adequate
- Epidural dosing 9-12mL including test dose (elderly patients require ↓dosing)
General:
- Balanced anesthetic w/ opioids, inhalational agent, N2O, & neuromuscular blocker
- Minimal opioids to facilitate extubation
- Deepen anesthetic during tunneling phase (3-5mcg/kg Fentanyl)
- Avoid hemodynamic extremes (β blockers often necessary)
Peripheral Revascularization
Anesthetic Management Postop
Stress reduction & pain control ↑MI risk postop Continuous EKG monitoring w/ ST analysis Control HR & BP Avoid anemia Hgb < 9g/dL Frequent peripheral pulse checks
LE Endovascular
Less invasive procedure to deploy stent & improve artery patency
General, neuraxial, or MAC
Percutaneous procedures (often MAC sedation)
Open access (femoral stenosis) consider GA
Carotid Artery Disease
1° carotid artery disease cause = atherosclerosis
Commonly occurs at the common carotid artery & internal/external carotid arteries
Carotid Artery Disease S/S
Fatal or debilitating stroke
TIA
Amaurosis fugax (transient monocular blindness attack)
Asymptomatic bruit
___ % strokes are ___
Approximately 87% strokes are ischemic (cerebral thrombosis or embolism)
< 20% strokes are preceded TIA
What disease accounts for up to 20% all strokes?
Extracranial atherosclerotic
Carotid Endarterectomy
Indications
↓symptoms & prevent stroke
Most common peripheral vascular surgery
Symptomatic patients w/ 70-99% carotid stenosis
How to manage asymptomatic < 70% carotid stenosis?
Medical therapies (ASA) Percutaneous angioplasty/stenting
Carotid Endarterectomy
Preop Assessment
Ask about recent symptoms? MI or TIA
Optimize medical management
- β blocker, statins, antiplatelet therapy
- HTN control, restore intravascular volume, reset cerebral autoregulation
- Diabetes control
Coronary artery disease common (1st treat carotids d/t CABG bypass & impaired cerebral perfusion w/ carotid plaques)
- Assess coronary angiograms
SIGNIFICANT Coronary Artery Disease S/S
Unstable angina
Decompensated heart failure
Significant valve disease
Carotid Endarterectomy
Anesthetic Management
Awake vs. GETA Continue ASA & cardiac medications Type & screen EKG to monitor leads II & V - rhythm disturbances & ST segment changes Cerebral oximeter A-line ACTs intraop Central line rare PIV x2 Fluid warmer Lower body warmer Arms tucked
Anterior Leads
V3 & V4
Inferior Leads
II, III, & AVF
Lateral Leads
I, AVL, V5, & V6
Septal Leads
V1 & V2
Carotid Endarterectomy
Medications & Infusions
Phenylephrine 20-300mcg/min OR 0.15-0.75mcg/kg/min
Remifentanil 0.05-0.2mcg/kg/min
Clevidipine 1mg or 1-2mg/hr double every 90sec up to 32mg/hr
Nitroglycerin
β blockers (Labetalol 5mg, Esmolol 10mg or 100-300mcg/kg/min, Metoprolol 1mg)
Ephedrine 5-10mg
Heparin & Protamine
Carotid Endarterectomy
MAP Goals
High-normal range especially during carotid clamping to increase collateral flow & prevent cerebral ischemia
Potential to induce HTN 10-20% above baseline during carotid clamping
Careful to prevent ↑MVO2
What response will be anticipated in response to carotid sinus manipulation? Why?
Bradycardia & HoTN d/t the baroreceptor reflex
How to treat sudden bradycardia & HoTN?
Stop surgical manipulation
Ask surgeon to infiltrate the carotid bifurcation w/ 1% Lidocaine to prevent further episodes
Where are baroreceptors located?
Carotid sinuses & aortic arch
Carotid Endarterectomy
Emergence
Assess neuro status - deficits require immediate attention (angiography, reoperation, or both)
HTN & tachycardia associated w/ emergence & extubation
- Consider β blocker or sedation to smooth emergence
↑pressure stresses the new suture lines
Awake Carotid Endarterectomy
Best way to monitor function
Patient has ball to squeeze Q5min checks
Minimal or NO sedation (Midazolam 0.5mg + Fentanyl 25mcg) to prevent interference w/ neurological assessment
Avoid Propofol
Consider Esmolol during induction/direct laryngoscopy to prevent sympathetic response
Patients potentially get hot & restless under the drapes
Uncover their legs
Prevent/treat HTN or HoTN
Awake Carotid Endarterectomy
Regional Anesthesia
Cervical plexus block to C2-C4 dermatomes
↓shunts indication
Improved hemodynamic stability
Reduced costs (operative time & avoid cerebral oximetry sensors)
Requires patient cooperation*
Cervical Plexus Block
Identify posterior sternocleidomastoid border
Inject along the posterior border medial surface
Potential to block accessory nerve → trapezius muscle paralysis
GALA Trial
Multicenter RCT
Carotid endarterectomy under general or local anesthesia
Finding = anesthetic technique was not associated w/ any significant difference b/w general vs. local
Cerebral Autoregulation
Hypocapnia ↓CO2 → vasoconstriction ↓CBF
Hypercapnia ↑CO2 → vasodilation ↑CBF
Carotid Artery Stump Pressure
GOAL
> 50mmHg
Stump pressure represents the back-pressure resulting from collateral flow through the circle of Willis via contralateral carotid artery & vertebrobasilar system
NIRS
Near-infrared spectrophotometry
Non-invasive technique to continuously monitor regional cerebral O2 saturation
Approximates VENOUS blood O2 saturation
Carotid Endarterectomy
Postop Complications
Thromboembolic & hemorrhage intracerebral events
HTN common d/t surgical carotid sinus baroreceptors denervation
HoTN common d/t baroreceptor hypersensitivity or reaction
Cerebral hyper-perfusion syndrome - abrupt ↑blood flow w/ loss autoregulation (S/S include headache, seizure, focal neurological deficits, cerebral edema, or intracerebral hemorrhage)
Cranial & cervical nerve dysfunction - RLN or SLN, hypoglossal, mandibular
- Bilateral RLN injury → bilateral vocal cord paralysis → life-threatening upper airway obstruction
Carotid body denervation - impaired ventilatory response to mild hypoxemia, central chemoreceptors impaired, worsened w/ opioid administration
Wound hematoma → requires immediate surgical intervention d/t airway impingement
Endovascular Carotid Artery Stenting
Percutaneous transluminal angioplasty & stenting
- Femoral access
- Aortic arch angiogram
- Selective common carotid artery origin & angiogram cannulation
- Guidewire placement into the external carotid
- Place embolic protection device
- Balloon angioplasty the lesion, advance stent delivery catheter across dilated lesion, deploy self-expanding stent, & stent balloon dilation
- Complete angiogram
- Access site management (hold pressure)
Aortic Diseases
Peripheral arteries - occlusive disease
Aorta & 1° branches
- Aneurysms
- Dissections
Aortic Aneurysm
Often medically managed
Dilation all 3 arterial layers
Occasionally produces symptoms d/t compression on surrounding areas
Aortic Aneurysm S/S
Asymptomatic
Present w/ pain d/t compressing adjacent structures or vessels
Aortic Aneurysm Diagnosis
CXR
Echo
CT/MRI
Angiography
Aortic Dissection
Surgical EMERGENCY
Mortality up to 58%
Occurs when blood enters the medial layer (minutes to hours)
Initially presents w/ tear in the intima layer
Aortic Dissection S/S
Severe pain in the posterior chest or back pain
Aortic Dissection Diagnosis
Unstable - Echo
Stable - CXR, CT/MRI, aortography, Echo
AAA
Abdominal aortic aneursym
Adventitial elastin degradation w/in vessels - genetic, biochemical, metabolic, infectious, mechanical, & hemodynamic factors
Concomitant aortoiliac occlusive disease present approximately 20-25% AAA patients
Abdominal Aortic Aneurysm
Risk Factors
Elderly male
Smoker
Family history (genetic component)
Atherosclerosis & HTN
Abdominal Aortic Aneurysm S/S
Asymptomatic pulsatile abdominal mass
Abdominal Aortic Aneurysm
Causes
Trauma
Mycotic infection (bacterial)
Syphilis
Marfan syndrome
AAA Repair
> 6cm diameter
Symptomatic < 5.5cm aneurysms
Expand > 0.5cm in 6mos period
5.5-5.9cm aneurysms are controversial, but often medically managed
Open Abdominal Aortic Reconstruction
More complex than CABG (no perfusionist or bypass pump)
Extensive incision & dissection
Clamping & unclamping the aorta & major branches → physiologic changes
Varying organ ischemia-reperfusion duration
Fluid shifts
Temperature fluctuations
Neurohumoral & inflammatory responses activated
What classifies AAA as relatively benign in terms rupture & expansion?
< 4cm diameter
LaPlace
↑diameter ↑wall tension (even when arterial pressure remains constant)
Systemic HTN enhances aneurysm enlargement
Ruptured AAA
Periop mortality ≈50%
Ruptured AAA Clinical Presentation
Classic triad:
- Hypotension
- Back pain
- Pulsatile abdominal mass (not always present after aneurysm ruptures)
EVAR
Endovascular abdominal aortic aneurysm repair
Less invasive
Reduced morbidity & mortality
↓hospital LOS
Now most common technique to repair AAA
EVAR Anesthetic Considerations
MAC sedation w/ local or regional vs. general
Patient able to lay supine, co-morbidities, aneurysm complexity, & surgical urgency (full stomach → RSI)
Steering guide sheaths require L arm arterial cut down
Hemodynamic management
Preserve organ perfusion
Blood loss & intravascular volume
Temperature
Radiation safety (fluroscopy)
Spinal Cord Blood Supply
Extensive collateral circulation
Anterior artery x1 (supplies ≈75%)
- Artery of Adamkiewics AKA originates off the descending aorta b/w T9-T12 & supplies lower 2/3 spinal cord 1°
Posterior arteries x2 (supplies ≈25%)
Early EVAR Complications
Paraplegia Stroke Acute renal injury Aneurysm rupture Pelvic hematoma
Late EVAR Complications
Endoleaks Aneurysm rupture Device migration Limb occlusion Graft infection
Endoleaks Treatment
Balloon angioplasty to the proximal attachment site to obtain to desired seal via remodeling the stent-graft
Type II - transarterial embolization via iliac arteries or retrograde embolization through the superior mesenteric or inferior mesenteric arteries
Last resort = open surgical treatment
CIN
Contrast induced nephropathy
PRESERVE trial
- Contrast load
- Pre-existing kidney disease
Limit contrast load & ensure adequate hydration to ↓iodine-based dyes viscosity
Aortoiliac Occlusive Disease
Most common sites chronic atherosclerosis = infrarenal aorta & iliac arteries
Surgical intervention only when patients are symptomatic
AORTIC CROSS-CLAMP
Factors to Consider
Pathophysiological changes are complex & depend on the following factors:
- Clamp level
- L ventricle status
- Degree periaortic collateralization
- Intravascular blood volume & distribution
- SNS activation
- Anesthetic drugs & techniques
- Heparinization
AORTIC CROSS-CLAMP
Complications
Arterial HTN above the clamp & HoTN below the clamp
ISCHEMIA → renal failure, hepatic ischemia, coagulopathy, bowel infarction, paraplegia
Aortic Cross-Clamp
Left Ventricle
↑LV volume & pressure
Healthy heart no significant ventricular distention or dysfunction
Impaired or stiff heart w/ ↓myocardial contractility & coronary reserve → ventricular distention → acute LV dysfunction & myocardial ischemia
Baroreceptor response to aortic cross-clamp:
↑aortic pressure
↓HR/contractility/vascular tone
Aortic Cross-Clamp
Metabolic Effects
↓O2 consumption 50%
Blood flow via tissues & organ below the aortic occlusion remains dependent on perfusion pressure
Independent from cardiac output
Physiological changes associated w/ aortic cross-clamp
HEMODYNAMIC Acute ↑SVR ↓CO ↑arterial BP above the clamp ↓arterial BP below the clamp ↑segmental wall abnormalities ↑LV wall tension ↓ejection fraction ↑pulmonary occlusion pressure ↑central venous pressure & coronary blood flow ↓renal blood flow METABOLIC ↓total body O2 consumption & CO2 production ↑mixed venous O2 saturation ↓total body O2 extraction ↑Epi/NE Respiratory alkalosis & metabolic acidosis
Aortic Cross-Clamp
Anesthetic Management
Vasodilators ↓afterload, wall stress, & MVO2 (Nitroprusside, NTG, Nicardipine, & Clevidipine)
Avoid long-acting medications
Perfusion to distal organs dependent on collateral circulation that originates proximal to the clamp or shunts
Aortic Cross-Clamp
Placement
Higher the clamp level → more significant impact on perfusion to vital organs
Thoracic > supraceliac > infrarenal
Aortic Cross-Clamp
Renal Effects
Aortic cross-clamping ABOVE the renal arteries ↓renal blood flow
Renal sympathetic blockade w/ epidural anesthesia to T6 level does not prevent or modify the severe impairment in renal perfusion & function
Renal failure after AAA repair
Pre-existing renal dysfunction
Ischemia during cross-clamp time
Thrombus or embolus interrupts RBF
Hypovolemia or HoTN
Renal Protection
Mannitol, loop diuretics, methylprednisolone, & low-dose Dopamine 1-3mcg/kg/min are used clinically to preserve renal function during aortic surgery
Mannitol
Renal protection
12.5g per 70kg
Improves renal cortical blood flow during infrarenal aortic cross-clamping & reduces ischemia-induced renal vascular endothelial cell edema & vascular congestion
*Also acts to scavenge free radicals, ↓renin secretion, & ↑renal prostaglandin synthesis
What patients are most vulnerable to the stress imposed on the cardiovascular system during aortic cross-clamping?
Patients w/ pre-existing impaired ventricular function & reduced coronary reserve
Pre-existing cardiac impaired ventricular function & reduced coronary reserve goals during aortic cross-clamping:
- Reduce afterload (Nitroprusside or Clevidipine)
- Maintain normal preload (IV fluids)
- Maintain CO (inotropes & MAP goals)
How to prepare prior to aortic UNclamping
↓volatile anesthetics
↓vasodilators or discontinue
↑fluid administration (volume)
↑vasoconstrictors
Severe HoTN unresponsive to interventions notify surgeon to reapply the cross-clamp
Consider Mannitol or NaHCO3
Open AAA
Anesthetic Considerations
Central line PIV x2 A-line Cross-matched blood *Rapid blood loss possible TEE Cerebral oximetry Esmolol, Nitroprusside, NTG, Clevidipine, Phenylephrine Heparin 100-300u/kg + Protamine to reverse Monitor ACTs Postop pain consider epidural Forced upper air warmer Fluid warms Do NOT warm the lower body during cross-clamp ↑injury to ischemia distal tissues d/t ↑metabolic demand (MVO2)
Aneurysm Hemodynamic Management
Avoid HTN d/t acute stress on the aneurysm → rupture
Maintain HR at or below baseline to prevent myocardial ischemia
Defer euvolemic resuscitation until aortic rupture surgically controlled ↑volume ↑pressure ↑bleeding
AAA
Postop Considerations
Aggressively control HTN & tachycardia
Achieve hemodynamic, metabolic, & temperature homeostasis prior to extubation
LOS variable
Pain - epidural vs. PCA
AAA Complications
Myocardial infarction Pneumonia (pulmonary edema) Sepsis Renal failure ↓tissue perfusion Hypothermia
Thoracic Aortic Aneurysm
Associated w/ known genetic syndromes
- Marfan syndrome
- Ehlers-Danlos syndrome
- Bicuspid aortic valve
- Non-syndromic familial aortic dissection
Marfan Syndrome
Caused by mutations in the fibrillin-1 gene
Ehlers-Danlos Syndrome
Connective tissue disorder
19 different genetic manifestations
Bicuspid Aortic Valve
Most common congenital anomaly resulting in aortic dilation/dissection
Occurs in 1% population
TAA Repair Approach
Descending aorta - L posterolateral thoracotomy w/ one-lung ventilation
Ascending aorta - supine w/ median sternotomy
Full or partial cardiopulmonary bypass
Thoracic Aortic Aneurysm
S/S
Typically reflects impingement on nearby structures
- Hoarseness d/t L RLN stretch
- Stridor d/t trachea compression
- Dysphagia d/t esophagus compression
- Dyspnea d/t lung compression
- Edema d/t superior vena cava compression
Thoracic Aortic Dissection
MI presentation
Acute, severe sharp pain in the anterior chest/neck or b/w the shoulder blades
Diminished or absent peripheral pulses
TAA Crawford Classification
Type I
Aneurysm involving descending thoracic & upper abdominal aorta
TAA Crawford Classification
Type II
Descending thoracic & most abdominal aorta
*Most difficult to repair
TAA Crawford Classification
Type III
Lower thoracic aorta & most abdominal aorta
*Most difficult to repair
TAA Crawford Classification
Type IV
Most or all abdominal aorta
DeBakey Classification
Dissection Aortic Aneurysms
Type I
Ascending aortic tear w/ dissection down entire aorta
DeBakey Classification
Dissection Aortic Aneurysms
Type II
Tear in the ascending aorta w/ dissection limited to only the ascending aorta
DeBakey Classification
Dissection Aortic Aneurysms
Type III
Tear in the proximal descending thoracic aorta w/ dissection from thoracic aorta to abdominal aorta
What cross-clamp timeframe correlates w/ minimal paraplegia risk?
< 30minutes
Artery or Adamkiewics
Anterior radicular artery
Exits the spinal cord at T9-T12
Supplies 1° blood flow to lower 2/3 spinal cord
Anterior Spinal Artery Syndrome
LE flaccid paralysis & bowel/bladder dysfunction
Sensation & proprioception are spared
Spinal Cord Protection
Limit cross-clamp time < 30min
Distal aortic perfusion (extracorporeal support)
CSF drainage ↓spinal cord perfusion pressure (CSF pressure ↑10-15mmHg w/ cross-clamping)
Intrathecal papaverine
Mild hypothermia ↓O2 requirements 5% each 1°C
Do NOT actively warm the LE d/t ↑metabolic requirements, acidosis, & ischemic injury
Barbiturates & corticosteroids
Avoid hyperglycemia
When to extubate after aneurysm repair?
Patient fully awake
Consider extubating in ICU d/t intraop fluid shifts
Notify ICU team when paralytic not reversed
Ruptured Aneurysm
EMERGENCY
Open or endovascular approach
Awake intubation vs. RSI w/ Etomidate 0.1mg/kg
14-16G PIVs
PRBCs
Rapid-infuser
Maintain normothermia
Dopamine, Epi/NE, Vasopressin
Place A-line, central line, & PA catheter after induction
TEE to assess ventricular function & filling pressures
Induction Medications
Fentanyl 10-15mcg/kg or Sufentanil 1-2mcg/kg
Etomidate 0.1-0.3mg/kg
Esmolol 100-500mcg/kg or Sodium nitroprusside 25-50mcg or Nitroglycerin 0.5-3mcg/kg
Lidocaine 1.5mg/kg
Rocuronium 1-2mg/kg
Hemodynamically stable patients Scopolamine 400mcg (amnesia)
Maintenance Medications
Narcotic/benzodiazepine
Low-dose volatile anesthetic Iso 0.3-0.5% or Sevo 0.5-1%
Epidural Morphine 2-4mg or Hydromorphone 0.5-0.8mg
Remifentanil 0.05-0.2mcg/kg/min
Cross-Clamp Medications
BEFORE: - Mannitol 0.25-0.5g/kg & Furosemide 20-40mg - Heparin 100-300units/kg DURING: - Nitroglycerin 0.5-2mcg/kg/min and/or 100mcg bolus - Sodium nitroprusside 0.5-2mcg/kg/min - Esmolol 50-300mcg/kg/min AFTER: - Volume
