Cardiac Intra-op Mgmt (pt 1/2) Flashcards
What is your room setup for CPB?
1) Monitors- Standard ASA monitors plus ABP/PAP/CVP, Cerebral Oximetry, BIS, TEE
2) Medications
-Emergency: Inotrope (Epinephrine), -Vasopressor (Phenylephrine), Vasodilator (Nicardipine)
-Routine: Induction agent, paralytic, narcotic, Heparin
3) Infusions READY
-Carrier (Aminocaproic Acid or NS)
-Vasopressor (Phenylephrine) and/or Inotrope (Epinephrine)
-Vasodilator (Nicardipine, NTG)
4)Blood available
5) Temporary Pacemaker
What is important to know with premedication and CPB?
-The risk of recall is higher in cardiac surgery as compared to other surgical procedures.
-Surgery itself coupled with insertion of arterial lines prior to induction is painful and anxiety provoking
-Resultant anxiety can produce an unwanted sympathetic response—>versed and fentanyl
-Be cautious in patients with CHF and low CO as well as patients with pulm HTN (don’t make them hypercarbic at all)
What are your pre-bypass goals?
- keep the patient where he lives
- the enemy of good is better: not chasing perfect numbers under anesthesia prior to correction of the underlying problem
- do no harm
What are the pre-bypass periods of GREATER stimulation?
-Incision
-Sternotomy and retraction
-Sympathetic nerve dissection (within pericardium)
-Pericardiotomy (highly stimulating if SNS nerves are dissected)
-Aortic cannulation
**inadequate anesthesia during these times increases circulating catecholamines, possibly resulting in hypertension, dysrhythmias, tachycardia, ischemia, or heart failure
What are the pre-bypass periods of LESS stimulation?
-Preincision
-Peripheral graft harvest
-IMA dissection: risk of extensive bleeding, may do small bolus of heparin, may need to hand ventilate (lungs get in the way)
-Venous cannulation
**risks during these periods include HOTN, bradycardia, dysrhythmias, and ischemia
What are your goals for induction?
“Low, Slow, and Neo”
-Render the patient unconscious
-Avoid worsening cardiac pathology: Myocardial ischemia, valvular pathology, Hypotension, tachycardia
-Blunt stress response
-All induction agents (except Ketamine) decrease vascular tone (arterial and venous), and cause some amount of cardiac depression
What do you do for induction with a CPB patient?
1) Lidocaine: 1-1.5mg/kg
-Provides local anesthesia to vein; blunts sympathetic response to intubation
2) Induction Agent
-Propofol – 1-2mg/kg – Preferred for LVEF >35%. Reduced dose due to cardiac disease, causes significant vasodilation and hypotension – up to 40%
-Etomidate – 0.2-0.3mg/kg – Preferred for LVEF <35%. Vasodilation/Hypotension – 10-15%, Cardiac depressant effects less profound than propofol, but can cause adrenal insufficiency for up to 24 hours after just 1 dose.
3)Neuromuscular blocker
-Succinylcholine 1-1.5mg/kg
-Rocuronium – 0.6-1mg/kg
-Vecuronium – 0.1mg/kg
How do you manage BP during induction?
-Induction doses - lower than in a non-cardiac patient
-Phenylephrine syringe readily available throughout the induction period
-LOW-SLOW-NEO
What is the most stimulating portion of induction?
Laryngoscopy.
-Avoidance of tachycardia is extremely important
-Increased myocardial oxygen demand
-Decreased diastolic filling time → Decreased stroke volume
-For cardiac disease that will be significantly worse with tachycardia - Esmolol syringe readily available (Severe CAD (Left Main Disease), Aortic stenosis, Mitral stenosis = NO TACHYCARDIA in these people)
When is Ketamine used for induction?
Ketamine – 2mg/kg
-Useful for patients with compromised hemodynamics (Hypovolemia due to hemorrhage or Cardiac Tamponade***)
-Will cause increases in sympathetic response (Tachycardia, hypertension)
-Avoid in patients with increased ICP
-Also not great for usual CAD patient
When could a Sevo Inhalational induction be used?
-Useful for Low EF
-Hemodynamic compromise less likely with inhalation induction
-Induction can be fast in patients with biventricular (especially RV) dysfunction. Concentration will be higher in the lungs due to poor perfusion.
What do you need to do pre-incision?
-Check pressure points
-Send baseline ABG/ACT
-Antibiotics: Vanc and Cefazolin
-Check lines (arms will be tucked)
-Start Amicar bolus & infusion (Aminocaproic acid): Antifibrinolytics are used to minimize bleeding and therefore decrease patient exposure to blood products.
-Hemodynamics: Keep them within 20% of baseline
How does stimulation change during the pre-incision period?
-Large stimulus during intubation & TEE placement
-Minimal stimulation during prepping & draping
-Decreased SNS tone + decreased stimulation = post induction slump.
-Maintain coronary perfusion.
How do you treat post-induction slump?
-Maintain coronary perfusion by maintaining preload/afterload & minimizing tachy/bradycardia
-Phenylephrine infusion very useful in maintaining vascular tone
-Fluid administration is not first line treatment for hypotension
Why is fluid administration not the first line tx for hypotension with CPB?
Avoidance of hemodilution (patients will get really hemodiluted when on bypass, so don’t want to give a lot of volume before going on bypass)
What should you do as you prepare for sternal incision?
-Ensure sufficient muscle relaxation
-Acceptable to use a little Neo to allow for appropriate administration of Fentanyl prior to sternal incision
-surgeon leaving to scrub= sternal incision is imminent
-Don’t want tachycardia with incision: give narcotics right before.
Incision = Increased stimuli
Prepare for hypertension and tachycardia
-Fentanyl +/- Propofol & Esmolol/ Nicardipine
What is Autologous Blood Removal?
-May take a unit off to sequester platelets and clotting factors from damage during CPB, with return at conclusion of bypass
-Stored in a bag with citrate phosphate dextrose solution (CPD) similar to banked blood.
What are the risks associated with Autologous Blood Removal?
-HOTN 2/2 hypovolemia
-Decreased O2-carrying capacity, which will be reflected on mixed venous sat
-Infection—maintain sterile technique for removal and subsequent return
What are the relative contraindications for Autologous Blood Removal?
-Left Main dz (can’t tolerate dec in O2 carrying capacity
-LV dysfunction
-Anemia with Hgb <12
-Aortic Stenosis
-Emergency Surgery
Why is autologous blood removal done?
Only for on-bypass procedures.
-Bypass machine makes plts inactive/dysfunctional due to heparin.
-Taking blood off so that it never touches the circuit and you have functional cells available at the end of surgery.
-Also reduces blood viscosity.
-Don’t give blood back until after bypass and protamine is given.
