Quality of care, part 3: bypass surgery

Kim A Eagle MDAlbion Walter Hewlett Professor of Internal MedicineChief, Clinical CardiologyCo-Director, Heart Care ProgramUniversity of Michigan, Ann Arbor, MI

Gerald O'Connor PhD, FACCProfessor of Medicine and of Community and Family MedicineAssociate Director, Evaluative Clinical SciencesChief, Clinical Research SectionDartmouth Medical School, Hanover, NH

Physician and patient metrics for quality of care are very different.

eg, occurrence of mediastinitis and leg wound infection may not be a ‘quality’ metric recognizable by patient

Administration may factor risk adjusted mortality rate and incidence of stroke into their own ‘quality’ indices.

Quality of care

Bypass surgery

From the clinician’s perspective, quality of care can be measured by the following:

(1) incidence of adverse outcomes

(2) patient’s functional outcome

Quality of care

Clinical standards

From the perspective of the institution where bypass surgery is performed, data collection should encompass, at the very least, the following measures:

in hospital mortality or 30-day mortality

incidence of new fixed neurological defects

mediastinitis

length of stay

time to extubation

Quality of care

Hospital standards

Bypass surgery

HS Luft and EL Hannan have both shown that outcomes after bypass surgery depend on strong volume effects which are pronounced at those institutions demonstrating the lowest volume levels.

However, the threshold to volume effect is hard to estimate, and at the lower end of the scale (100 surgeries per year), the standard error becomes very large.

Quality vs volume effects (i)

Bypass surgery

Good performers who operate at low volumes can be identified in every study of volume and outcomes.

Also, individual physicians may operate at a number of different centers, so they may be high volume operators operating at low volume sites.

Quality vs volume effects (ii)

“I think it's a rather complex question and one for which we have a general answer, that practice makes perfect, but not a specific answer that we can apply to every center right now.” Gerald O'Connor PhD, FACC Chief, Clinical Research Section Dartmouth Medical School on Volume effects in bypass surgery outcomes

Bypass surgery

Quality of care

Outcomes

Structure Process

Bypass surgery

In 1987, HCFA began to publish mortality rates.

The Northern New England experience revealed a wide ranging mortality, from 2-6%, among 6 hospitals with a homogeneous patient population.

Substantial differences in mortality were due to unmeasured processes of clinical care.

Establishing quality measures

Bypass surgery

Establish clinical care “benchmarks”.

Institute a bypass surgery multidisciplinary team approach with input from cardiac surgeons, cardiologists, anesthetists, reperfusionists and nurses.

Cardiac surgery becomes a “team sport”.

Identifying processes of clinical care

Bypass surgery

A study in New England of over 8600 bypass patients and 350 deaths identified the mode of death in each case1.

2/3 of deaths in cardiac surgeries were found to be a consequence of low cardiac output syndrome and 2/3 of these patients were noted to have a normal ejection fraction pre-operatively.

Fatal low cardiac output syndrome accounted for 80% of the difference in aggregate mortality rates.

Identifying mode of death

1 O'Connor GT, Birkmeyer JD, Dacey LJ, et al. Ann Thorac Surg 1998;66(4):1323-8

i. pre-operative management of ischemia

ii. hand-offs between cardiologists, cardiac surgeons, anesthetists and nurses

iii. perfusion and myocardial protection methods

iv. method of separating from cardiopulmonary bypass

v. diagnosis and treatment of low-output heart failure in the intensive care

High leverage areas of care

Low-output outcomes

Establish a method of pre-operative risk classification, to identify patients at low, medium or high risk of having low cardiac output post-operatively.

Improve the pre-operative care of patients with unstable angina and CHF.

Establish physician responsibilities among cardiologists, cardiac surgeons and anesthetists in the pre-operative 6 hour window.

Pre-operative care (i)

Improving outcomes

Be selective in the use of pulmonary artery catheters pre-operatively, especially in patients who have a higher likelihood for the low cardiac output syndrome.

Ensure adequacy of beta-blockade prior to surgery, including the use of short acting beta-blockers in the operating room.

The use of ASA pre-operatively may reduce rates of graft failure without excess bleeding.

Pre-operative care (ii)

Improving outcomes

Prevent hemodilution. A hematocrit below 20-21% is associated with an increased risk of mortality and increased rates of return to bypass and the need for IABP intra-operatively.

Establish uniform use of internal mammary arteries, even in elderly patients or the acute case.

Operative care (i)

Improving outcomes

Avoid inotropes at bypass separation. The increase in myocardial oxygen demand from routine use of inotropes at cardiac bypass separation may be detrimental.

Develop a standard protocol for high-risk patients who may be identified pre-operatively.

Operative care (ii)

Improving outcomes

Improve the recognition and treatment of low cardiac output in the intensive care unit.

Establish a definition of low cardiac output, eg, a cardiac index of 1.8 or below with or without support. The etiology may then be ascribed to preload, afterload, rate, rhythm or contractility.

Postoperative care

Improving outcomes

Physicians should not blindly assign a ‘number’ beyond which it is assumed quality occurs.

Significant areas exist which should be a focus for improving outcomes.

ACC/AHA guidelines1 on bypass surgery are available and include a formula enabling physicians to calculate risk adjustment and estimate patient risk.

Improving process and outcome

Bypass surgery

1 Eagle KA, Guyton RA, Davidoff R, et al. J Am Coll Cardiol 1999;34(4):1262-347