Levels of Circulating Ketone Bodies in Patients Undergoing Cardiac Surgery on Cardiopulmonary Bypass

Ketone bodies (KBs) are energy-efficient substrates utilized by the heart depending on its metabolic demand and substrate availability. Levels of circulating KBs have been shown to be elevated in acute and chronic cardiovascular disease and are associated with severity of disease in patients with heart failure and functional outcome after myocardial infarction. To investigate whether this pattern similarly applies to patients undergoing cardiac surgery involving cardiopulmonary bypass (CPB), we analysed prospectively collected pre- and postoperative blood samples from 192 cardiac surgery patients and compared levels and perioperative changes in total KBs with Troponin T as a marker of myocardial cell injury. We explored the association of patient characteristics and comorbidities for each of the two biomarkers separately and comparatively. Median levels of KBs decreased significantly over the perioperative period and inversely correlated with changes observed for Troponin T. Associations of patient characteristics with ketone body perioperative course showed notable differences compared to Troponin T, possibly highlighting factors acting as a "driver" for the change in the respective biomarker. We found an inverse correlation between perioperative change in ketone body levels and changes in troponin, indicating a marked decrease in ketone body concentrations in patients exhibiting greater myocardial cell injury. Further investigations aimed at better understanding the role of KBs on perioperative changes are warranted.

Heparinized cardiopulmonary bypass circuits and low systemic anticoagulation: an analysis of nearly 6000 patients undergoing coronary artery bypass grafting

OBJECTIVE

Heparin coating of cardiopulmonary bypass circuits reduces the inflammatory response and increases the thromboresistance during extracorporeal circulation. These properties enables a lower systemic heparin dose, which has been shown to reduce the need for blood transfusions. Experience with this technique accumulated over 11 years has been analyzed.

METHODS

All patients underwent on-pump coronary artery bypass grafting with heparin-coated circuits. Apart from some patients receiving a high intraoperative dose of aprotinin, the systemic heparin dose was reduced, with a lower level of an activated clotting time of 250 seconds during extracorporeal circulation. The overall strategy aimed at a fast-track regimen, with early extubation, minimal use of blood transfusions, and rapid postoperative recovery.

RESULTS

Altogether, 5954 patients were included; 1131 (19.0%) were female (median age, 70 years), and 4823 were male (median age, 65 years). The median additive EuroSCORE was 3 (range, 0-14; mean 3.5 ± 2.5). No significant signs of clotting were seen in any part of the extracorporeal circuit. Bank blood products were given to 427 (7.2%) patients. Median extubation time was 1.7 hours. The stroke rate was 1.0%, transient neurologic deficits occurred in 0.7%, and perioperative myocardial infarction occurred in 1.2%. On the fifth day, 88.1% of the patients were physically rehabilitated and ready for discharge. Thirty-day mortality was 0.9% (54 patients).

CONCLUSIONS

The experience with this patient cohort including mostly low- to medium-risk patients with a relatively short cardiopulmonary bypass time indicates that coronary artery bypass grafting performed with heparin-coated circuits and reduced level of systemic heparinization is safe and results in a very satisfactory clinical course. No signs of clotting or other technical incidents were recorded.

Heparin-coated circuits and reduced systemic anticoagulation applied to 2500 consecutive first-time coronary artery bypass grafting procedures

BACKGROUND

In contrast to the widespread popularity of off-pump techniques for coronary artery bypass grafting, our institution has chosen a different strategy, emphasizing improvements in the technology for extracorporeal circulation, as well as simplifying surgical and clinical management. The clinical short-term results of this approach were analyzed.

METHODS

The on-pump strategy includes routine use of heparin-coated circuits combined with low systemic heparinization (activated coagulation time of more than 250 seconds), intention of total revascularization within limited ischemic times and pump times, minimal use of blood transfusions, early extubation, and rapid postoperative recovery. The data from the first 2,500 consecutive first-time coronary artery bypass grafting patients (January 1998 to February 2002) treated with this protocol were retrospectively analyzed.

RESULTS

There were 487 female (median age 68 years) and 2013 male (median age 64 years) patients. A median of four (one to nine) (mean 4.5 +/- 1.2) distal anastomoses were created, and the median aortic cross-clamp time and pump time were 34 and 54 minutes, respectively. At least one internal mammary artery was used in 99.7% of the patients. Blood or bank blood products were given to 118 patients (4.7%). Median extubation time was 1.5 hours. The stroke rate was 0.8%, transient neurologic deficits occurred in 0.6% of the patients, and the incidence of perioperative myocardial infarction was 1.1%. By the fifth day, 91% of the patients were ready for discharge. Seven patients (0.28%) died during their hospital stay.

CONCLUSIONS

Coronary artery bypass grafting with heparin-coated cardiopulmonary bypass circuits and reduced systemic anticoagulation resulted in excellent clinical results, with minimal blood transfusions and rapid postoperative mobilization. The high number of grafted coronary arteries indicates complete revascularization in most patients, which is known to be a significant predictor of long-term event-free survival.

Rapid recovery protocol applied to 5,658 consecutive "on-pump" coronary bypass patients

BACKGROUND

Increasing hospital costs, restricted resources, and new surgical strategies have stimulated effectiveness of all routines in cardiac surgery. Over a 10-year period, 5,658 consecutive patients undergoing coronary artery bypass grafting followed a protocol aiming at short postoperative intubation times and rapid physical rehabilitation.

METHODS

The patients were prepared for rapid recovery, emphasizing (1) preoperative education and respiratory training, (2) low-dose fentanyl anesthesia, (3) limited ischemic times and pump times, (4) mild hypothermia and rewarming to a rectal temperature of 36 degrees C, (5) restricted use of extended monitoring, (6) autologous blood salvage to avoid allogeneic blood transfusions, and (7) active physical training from postoperative day 1. All in-hospital data relevant to these steps were prospectively stored in a database.

RESULTS

The median extubation time after arrival in the intensive care unit was 1.5 hours (0 to 320 hours). More than 99% of the patients were extubated within 5 hours. Sixty-two patients (1.1%) were reintubated and ventilated for a median of 24 hours (1 to 430 hours), mostly due to resternotomy for bleeding or cardiopulmonary decompensation. In total, 5,594 patients (98.9%) were able to sit in a chair the first postoperative day. Within the fourth postoperative day, 82.5% were able to move freely in the hospital area and were in fact physically fit for hospital discharge. Allogeneic blood products were given to 3.9% of the patients. Twenty-three patients (0.41%) died in-hospital.

CONCLUSIONS

With the application of a protocol for rapid physical recovery in patients undergoing "on-pump" coronary artery bypass grafting, extubation within 1 to 2 hours was safe and feasible in most patients. After 5 hours, 99.3% of the patients were extubated, with a reintubation rate of 1.1%. More than 80% of the patients were fully physically mobile within 4 days after the operation.