On-Pump CABG (Guide)

Preoperative Evaluation and Questions: How many and which vessels? Grafts from where? Is the surgeon planning to use radial artery for a graft? LV function? Valve disease?

Is the patient High Risk? High Risk = EF <40%, LVEDP >18, CI <2.
Baseline neurologic status? Renal function?
Is there an indication for TEE? (high risk pt? co-existing valve disease?).

Risk: Mortality 2-4%; Morbidity: Cognitive decline post-op in Pts >60yo = 26%, CVA 2-4%, MI 3-6%. [Jaffe RA and Samuels, SI. Anesthesiologist’s Manual of Surgical Procedures, 4th ed.]

Induction: Appropriate induction of anesthesia for cardiac surgery is critical unique. By definition these patients have areas of myocardium that are at-risk or already ischemic. Traditional “Cardiac” induction consists of high dose narcotics, usually Fentanyl 10-100mcg/kg, Sufentanil 2-20mcg/kg, or Morphine 1-5mg/kg. Sufentanil has been associated with faster induction and recovery than Fentanyl or Morphine [Sanford TJ Anesth Analg. 1986 Mar;65(3):259 PMID: 2937352]. However, a recent study reported Morphine resulted in better quality of recovery and post-op pain control than Fentanyl [Murphy GS Anesth Analg 2009; 109:311]

Lines and Monitors: Arterial line should be placed prior to induction. Right IJ MAC can be placed pre or post induction. Pulmonary Artery Catheter placement is common for nearly all cardiac surgeries. There is debate about whether PAC use is beneficial [Sandham JD N Engl J Med 2003 Jan 2;348(1):5]. However, many cardiac surgeons and anesthesiologist are accustomed to the information provided by the PAC and use this info to guide treatment intra-op and post-op.

Intraoperative Goals and Events:

Opioids as primary induction agent to preserve hemodynamics. Need a hypnotic to ensure lack of consciousness and amnesia (Midaz or Sevo most common). Maintain Cerebral/Coronary Perfusion Pressure and Oxygenation. If planning “fast track” use lower dose Fentanyl (10-15mcg/kg).
Pre-CPB: Blood in room for Sternotomy, (especially if Redo), Lungs down, Internal Defibrilator connected, Pacer box available and functioning.
CPB: Heparin (given by Perfusionist), ACT >350, Mean BP managed by Perfusionist, PAC pulled back 5cm, empty foley to get accurate “on-pump” urine out-put, watch aortic cannula for air.
Post-CPB: Checklist = Hemodynamics (rhythm, BP), Ventilation (start when pulsatile PA tracing), Ca++, Acid/Base, Hb, Temp (>36), K+.

Surgical Course
Line placement (a-line, PAC) w/ sedation pre-op. Induction, Baseline ABG/ACT, Graft harvest, Sternotomy (lungs down, have blood available), CBP access established (MAP <70 prior to Aortic cannulation to reduce chance of dissection), Start CPB (Stop ventilation, KVO all gtts, “reto” connected to PA transducer), Cooling to ~26, Graft anastomosis, Rewarming (more Midaz/Panc with rewarming), Wean from CPB (Pressors PRN), TEE to eval EF/Wall motion.

EBL: 500-1000ml

Duration: 3-4 hrs

Pain: 7-8/10

Post-Operative Concerns, Transport, Disposition: To ICU intubated. If “fast track” then plan for extubation 6-8hrs post-op. Potential for recall.
Graft survival: Vein grafts = 50% significant stenosis at 10yrs, Internal Mammillary = 90% patent at 10yrs.

Evidence-Based Medicine:
Preconditioning: The cardio-protective effect of volatile anesthetics has received much attention in recent years. There is certainly experimental evidence showing post-ischemic protection and suggested mechanisms. [Zaugg M Anesthesiology 2002; 97:4-14]. The most recent review article on this topic indicated that, although there is experimental and clinical data supporting cardioprotective effects of volatile anesthetics, there is still no evidence of an improvement in morbidity or mortality [De Hert SG Anesth Analg 2005; 100:1584-1593]. One interesting question to ask is, if current practice is to use Volatiles for cardiac surgery will an improvement in M & M change our practice? Likely not. However, the trend toward “fast-track” and even “ultra fast-track” cardiac surgery may eventually lead to a change in the standard use of volatile anesthetics in favor of TIVA. There is one recent study that compared Volatiles to TIVA for CABG. There was a difference in hospital length of stay (12 days for the TIVA group, 9 days for the SEVO group and 9 days for the DES group.) and 1 year mortality (12.3% in the TIVA group, 3.3% in the sevoflurane group, and 6.7% in the desflurane group), but the group assignment (TIVA, Sevo, Des) was not a significant independent predictor of 1 year mortality. [De Hert SG Anaesthesia 2009; 64: p953–960] Again, this only matters if we think TIVA is the future of anesthesia for cardiac surgery, which it may not be.