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cardiac constable reading > Chapter 6 Anesthetic Mgmt. Pre CPB > Flashcards

Chapter 6 Anesthetic Mgmt. Pre CPB Flashcards

1
Q

What is incidence of ischemia during induction of anesthesia and institution of CPB

A

7-56%

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2
Q

what are ways to manage high risk period between induction of anesthesia and institution of CPB-4 things

A

1) Optimize O2 supply/Demand
2) optimize preload, after load, contractility, HR, rhythm
3) keep patients vital signs close to where they “live”-meaning if patient vital signs close to baseline value, and they are stable, strive to keep vitals at baseline
4) CI may be less than 1.8 pre anesthesia-O2 consumption will decrease after induction of anesthesia, so this MAY be adequate
5) patients are frequently very sick so if you are having issues ask for help “do no harm”

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3
Q

Name 6 high levels of stimulation during pre CPB period.

A

1) incision
2) sternal split
3) sternal spread
4) Sympathetic nerve dissection
5) pericardiotomy
6) aortic cannulation

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4
Q

What clinical findings are evident during high stimulation times during CPB, name 5

A

increased catecholamine levels resulting in

  • hypertension
  • dysrythmmias
  • tachycardia
  • ischemia
  • heart failure
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5
Q

List 4 low level stimulation events during CPB

A

1) pre incision
2) internal mammary artery dissection
3) radial artery harvesting
4) CPB venous cannulation

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6
Q

Name some risks associated with low level stimulation period

A
  • hypotension
  • bradycardia
  • dysrhythmias
  • ischemia
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7
Q

How long does pre incision generally take? What are some things you need to check during this time? 13 things listed..

A

Pre incision usually takes 5-20 minutes.
Check pressure points, avoid common nerve injuries, prevent alopecia, check heels, tape eyes, check FGF, Lines, monitors, labs, antibiotic administration, body temperature, urinary output, and depth of anesthesia before incision.

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8
Q

What 3 causes of ischemia to pressure points during CPB (example heels, head)? What are the results of ischemia?

A
  • compression on a particular area, cooler temperature of patient, decreased perfusion pressure
  • peripheral neuropathy, damage to soft tissues, alopecia (head)
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9
Q

How do brachial plexus injuries occur? Name 5

A
  • if arms are hyperextended
  • chest retraction is excessive (occult rib fracture with sternal retractor, or during IMA dissection even if both arms tucked at sides)
  • arms extended >90 degrees
  • minimize pectorals major muscle tension
  • thumbs up not down on arm boards
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10
Q

Name some reasons for a)Ulnar nerve injury b)radial nerve injury

A

a) compression of olecranon against hard surface (pad elbow, avoid direct contact with hard surface)
b) compression of upper arm again the “ether screen” or the support post of the chest wall sternal retractor used in IMA dissection)

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11
Q

name some ways to prevent alopecia, how long can take for it to occur

A

-can occur 3 weeks after the operation 2ndary to ischemia of the scalp, particularly during hypothermia, pad head, and reposition frequently

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12
Q

A)How can you maximize inspired O2 tension, and B)can using a small amount of air effect O2 tension?

A

A)maximize O2 tension by using 100% O2
B)adding air to O2 according to pulse oximetry readings may prevent absorption atelectasis and reduce risk of O2 toxicity

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13
Q

Can N2O be used during pre CPB period? What effects does it have (name 4)

A

Yes. causes

1) decrease in concentration of inspired FIO2
2) increase in PVR in adults
3) increase in catecholamine release
4) induce ventricular dysfunction

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14
Q

If you use N2O in a patient with evolving myocardial infarction or ischemia, what could happen

A

Do not use in these patients. It causes a decrease FIO2 and catecholamine release and can increase the risk of ischemia and infarct size.

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15
Q

After patient position is established, lines are inserted, what do you do in terms of lines and monitors in the CPB patient?

A
  • ensure free flow of IV
  • ensure proper waveforms of all lines, establish appropriate zero reference points for all transducers
  • ensure that stopcocks are accessible, and securely taped down
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16
Q

In terms of cardiac monitors, what should be evaluated after intubation?

A
  • cardiac index
  • ventricular filling pressures
  • MVO2
  • cardiac work index
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17
Q

If using TEE, what should be checked

A
  • check and document status of probe, regarding dental and oropharyngeal injury
  • make sure TEE probe is not in a locked position, as this may lead to pressure necrosis in GI tract
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18
Q

After intubation, why would you check ABG?

A

-check ABG 10 minutes after FIO2 has been consistent to confirm adequate ventilation, compare with ETCO2 and pulse oximetry (maintain normal ETCO2 are hypercapnia may increase pulmonary vascular resistance)

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19
Q

Why would you check a glucose?

A
  • high glucose levels should be treated to minimize neurologic injury and decrease post-op infection rates
  • maintain sugar in tight parameter range, monitor trends, avoid huge swings in glucose levels
  • continuous infusion of insulin may be indicated to reduce risk post operatively
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20
Q

What coagulation study may be performed pre-operatively

A

ACT (Activated clotting time) may be drawn with ABG to determine a heparin dose response curve baseline to determine initial heparin dosage

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21
Q

Name some indications for giving aprotinin, what should you do when giving this? What are risks/benefits? what are safer alternatives?

A
  • Aprotinin is an antifibrinolytic drug given to minimize bleeding, reduces rate of blood transfusion by 30%, and reduces incidence of re operation due to post-op bleeding.
  • you should give it after giving any other drugs, to ensure that if it causes a reaction you can pin point it as the reason for an allergic reaction.
  • aprotinin is associated with myocardial infarction, heart failure, cerebral vascular events, encephalopathy, coma, renal failure
  • give TXA, epsilon aminocaprioic acid instead
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22
Q

How would you prepare for saphenous vein excision? How does this effect preload, when is it harmful?

A
  • lift legs above level of heart, and this increases preload
  • may be harmful in someone with poor ventricular reserve
  • lift legs slowly
  • may have to adjust ventilation to ETCO2 readings
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23
Q

If insufflation is used, what bad things can happen, and what can you do to reduce injury to patient

A
  • if insufflation is used may have CO2 embolism (frail elderly patients with fragile tissue at increased risk)
  • maintain high right atrial pressure >5
  • add PEEP
  • hemodynamic deterioration may occur 2ndary to patent foramen ovale in left heart and coronary circulation with insufflation
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24
Q

Name some temperature considerations in the pre-op period for CPB patients.

A
  • on bypass patients do not need to be warmed
  • gradual cooling 34-36 degrees C decreases O2 consumption and CO2 production
  • increases SVR and PVR
  • increases in blood viscosity
  • decrease in CNS function and CMRO2, CBF
  • MAC decreases 5% for each decrease in degree C
  • decrease in renal BF and UOP
  • minimal increase in catecholamines
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25
Name some indications and interventions to maintain UOP and renal function
- address low UOP immediately - use info from CVP, PA cath to direct fluid therapy - avoid or treat hypotension - low dose dopamine (does not prevent preoperative renal dysfunction) - ANP, fendolopam, lasix (10-40mg), bumetanide (0.25-1mg to maintain renal tubular BF) mannitol(0.25g/kg) to redistribute renal BF to cortex and maintain tubular flow - contrast dye-maintain adequate fluid administration to prevent injury
26
Where should you keep your MAP perioperatively
between patients pre operatively low and high ranges
27
what happens regarding pulmonary status to a patient treated with vasodilator for hypertension?
hypoxemia 2ndary to inhibition of hypoxic pulmonary vasoconstriction--increase FIO2
28
how can you prevent absorption atelectasis
mix air/O2 together
29
Prior to incision, do these two things..
1)narcotic administration 2)ensure adequate muscle relaxation
30
Despite the use of monitors, what is the best way to assess oxygenation and perfusion
presence of bright red blood
31
During skin incision, besides ensuring adequate depth of anesthesia, what mediations may be given to combat tachycardia/hypertension
mediations with short half life - vasodilators (NTG 20-80ug bolus) SNP - beta blockers (esmolol .25 -1mg/kg)
32
during use of power saw, what should you do to lungs
deflate lungs to avoid damage to lung parenchyma
33
Aside from high doses of narcotics during sternal split, what other drugs should you use to prevent recall?
amnesic agents benzos-be careful because they can reduce SVR and contractility especially in conjunction with narcotics scopolamine-0.2-0.4 mg IV-may prolong emergence, cause tachycardia, dilated pupils N2O-may cause catecholamine release, LV dysfunction, increased PVR, increased risk of hypoxia inhalation agents droperidol (0.065-2.5 mg)-hypotension, blocking of alpha 1 receptors ketamine 5-100 mg-SNS stimulation propofol 1 -50 mg-decreaesd BP, CO sodium thiopental 25-150 mg decreased BP, CO
34
what is "gold standard" to decrease awareness in a fast track patient to prevent recall
although they can depress myocardium,cause brady, tachy, dysrhythmias, or decreases in SVR, they are gold standard technique to "fast track patient"
35
After sternal spread, check the following
1)visual confirmation of lung inflation 2)integrity of PA cath (if inserted)
36
During internal mammary artery and radial artery dissection-1)which IMA is used, 2)what issues do you encounter, 3)where do you keep transducers at, 4)what can happen to radial nerve, 5)how much heparin do you give during vessel dissection, 6)why would you give papaverine, and 7)what flow rate do you want IMA to be considered acceptable for grafting
1) left IMA to LAD 2) difficulties in BP measurement-left sided radial artery lies may not function because of compression of subclavian artery with sternal retraction, same might happen on right side 3) keep transducer at level with R atrium 4) radial nerve injury due to compression by support post of favaloror retractor 5) give heparin 5000 Units during vessel dissection 6) papaverine to dilate and prevent spasm 7) IMA BF should be 100ml/min (25 ml in 15 seconds)
37
what happens to ADH
increased levels due to surgery, positive pressure ventilation
38
ACTH levels
adrenocorticotropic hormone-increased-causes increases in cortisol levels
39
cortisol
increased, leads to increase in glucose level
40
catecholamines
increased, epi, NE, dopamine due to adrenal medulla stimulation
41
insulin
decreased in proportion to glucose
42
Growth hormone
increased, causes increased protein synthesis
43
renin
increased, converts Angio I to angio II causing vasoconstriction and hypotension
44
prolactin
increased levels, due to increased level of endorphins
45
glucagon
increased inotropy
46
renal effects of surgery
increased aldosterone, decreased UOP (due to ADH) decreased K levels and increased Na 2ndary to aldosterone, decreased renal BF
47
What is MAC BAR
MAC that blocks SNS response in 50% of patients, about 1.5 MAC, to reduce SNS response MAC of 2 needed MAC bar associated with myocardial depression, decreased BP, increased PCWP
48
what do beta blockers do
attenuate increased in HR and O2 demand, may cause bronchospasm,
49
what do alpha 2 agonists do
decrease peripheral efferent SNS activity, decrease in catecholamine levels (reduce NE) enhance CV stability, decrease HR, BP, and SVR perioperatively, may cause brady and hypotension, especially with Ace inhibitors or vasodilators, and in high doses cause increased PVR, hypertension, decreases in CI
50
what can vasodilators do
used to treat increases in SVR often secondary to NE level increases reflex increase catecholamines, reflex increase in HR, inhibition of hypoxic pulmonary vasoconstriction
51
what can local anesthetics do
decrease GH, ACTH, catecholamine responses to lower abdominal pressures thoracic epidural anesthesia is inconsistent in blocking stress response to thoracic surgery, due to insufficient somatic or SNS blockade from unblocked affronts -decreased SVR, bradycardia, decreased isotropy from sympathectomy, and risk of epidural hemorrhage after heparinization
52
What can cause hypotension perioperatively
- rule out mechanical causes (surgical compression of heart, technical issues with measuring techniques) - myocardial ischemia - increased airway pressures - tension pneumothorax - ischemia - bradycardia, tachycardia, dysrhythmia, decreases in SVT, constriction pericarditis, steroid depletion with chronic steroid use
53
what causes HTN perioperatively
``` less common with LV dysfunction SNS discharge light anesthesia hypoxia hypercapnia hypervolemia withdrawal syndromes (beta clockers, clonadine, ETOH) thyroid storm, malignant hyperpyrexia, pheochromocytoma ```
54
what causes sinus bradycardia/interventions
vagal stimulation most common treat any HR associated w decreases in BO HR
55
sinus tachycardia causes, interventions
most significant risk factor for preoperative ischemia >110 BPM 32-63% incidence of ischemia -SNS from light anesthesia pancuronium, scopolamine, inotropic agents, isoflurane, aminophylline agents, beta agonists, MAOI or TCA, hypovolemia, ischemia, hypoxia, hypercapnia, CHF, withdrawal (beta blockers, clonadine ETOH) thyroid stop, malignant hyperpyrexia, pheochomocytoma
56
causes and for dysrythmias
placement of pursestrings sutures, cannulation vent placement, lifting heart to study anatomy, pre existing dysrhythmias, light anesthesia, hypercapnia, N2O, halothane, pancuronium, inotropic agents, aminophylline preparations, beta agonists, MAOI and TCA, electrolyte abnormalities (hypokalemia), Hyper/hypotension, ischemia, hypoxemia.
57
treatment of tachycardia
``` rule out ventilation issues try a small dose of narcotic give volume is low preload evident address other causes of tachycardia beta blocker with esmolol, especially if ischemia noted ```
58
treatment of dysrhythmias with potassium
most common pre bypass is manipulation of heart | give K pre CPB but be careful because cardiopelegia contains K, try replacing Mg
59
treatment of SVT
stop mechanical irritation-use vagal maneuvers, adenosine, digoxin, ca channel blockers, beta blockers, neosynephrine, edrophonium
60
treatment of PVC
stop mechanical irritation | lidocaine, procainamide, beta blockers, amiordarone
61
cardioversion or defibrillation during surgery
atrial, ventricular tachy, VFIB small paddles directly to heart with chest open 10-25J for cardioversion synch atrial and VTACH defib in non synchronized mode 300J external cardioversion-when chest is closed 25-300
62
describe heparin
preferred agent for anticoagulation during cardiac surgery, water soluble mucopolysaccharide, binds to anti thrombin III, a protease inhibitor, increases the speed of reaction between ATIII and activated clotting factors (II, IX, X, XI, XII, XIII), onset is immediate, half life 2.5 hours, reversed by protamine sulfate, 50% metabolized in liver/reticuloendothelial system 50% unchanged in renal elimination, give 300 units/kg or per ACT baseline, give directly into central vein or into RA, aspirate to confirm blood return
63
what is normal ACT
105-167 seconds, monitors effect of heparin on coagulation, an ACT of at least 300 seconds is safe for initiating CPB and 3000-5000 units of heparin included in prime pump, 400-480 better before CPB. If ACT
64
a) Describe cannulation b) pericardial sling and pursestrings sutures c) can you run nitrous at this time
a) pericardial sling is created before cannulation to increase working space, provide a dam for external cooling fluid, and to lift heart (can decrease venous return and lead to hypotension) b) pursestrings sutures-used to keep aortic and venous cannulation in place and to close incisions after cannulation c) no to N20
65
before cannulation, always give this drug
heparin
66
during cannulation, insert what cannula first
aortic, check for bubbles, give test transfusion of 100mL to ensure proper placement of cannula
67
during cannulation, keep SPB at what range
90-100mmHG to reduce risk of aortic dissection, use CPB is necessary
68
why would you apply peep during cannulation
increase intracardiac pressures to avoid air entrainment during cannulation of the right atrium and Left ventricle
69
what are complications of aortic cannulation
1) embolic phenomena from air or plaque Dislodgment 2) hypotension 3) partial occlusion clamp used for cannulation may narrow aortic lumen, check aortic pressure immediately when clamp is applied (more common in kids) 4) dysrhythmias 5) aortic dissection due to cannula misplacement-pulsatile pressure from aortic cannula correlates with the radial MAP rules out dissection 6) bleeding (major if aorta is torn)
70
what are complications of venous cannulation
1) hypotension-give 100mL increments of fluid 2) mechanical compression of heart=hypotension, especially with IVC 3) bleeding (could be RA, SVC, IVC) 4) dysrhythmias 5) air
71
contraindications to autologus preoperative blood removal
left main coronary disease LV dysfunction anemia with HGB

cardiac constable reading (3 decks)

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