Embolic activity during in vivo cardiopulmonary bypass.

Neurologic injury after cardiac surgery is principally associated with emboli. Although much work has focused on surgical sources of emboli, less attention has been focused on emboli associated with the heart-lung machine. We tested whether emboli are associated with discrete processes during cardiopulmonary bypass (CPB). One hundred patients undergoing cardiothoracic surgery were enrolled between April 2008 and May 2011 at a single medical center. During each surgical procedure, emboli were counted in three CPB locations: the venous side (Channel 1), before the arterial line filter (Channel 2), and after the arterial line filter (Channel 3). We used prespecified event markers to identify perfusionist interventions. Identical circuits were used on all patients. Of the 100 patients enrolled, 62 underwent isolated coronary artery bypass grafting (CABG), 17 underwent isolated valve operations, and 21 underwent CABG plus valve. Median counts across Channels 1, 2, and 3 were 69,853, 3,017, and 1,251, respectively. The greatest contributor to emboli in Channels 1, 2, and 3, respectively, were achieving the calculated CPB flow, opening of the electronic arterial line clamp, and introducing a hemofilter. The circuit technology was efficient in reducing total emboli counts from Channels 1-2 irrespective of the size of the emboli. Nearly 71% of all emboli 30-100 microm in size were removed from the circuit between Channels 2 and 3. No significant association was found between emboli counts and S100B release. Emboli occur frequently during CPB and are predominantly associated with the initiation of bypass, operation of the electronic arterial line clamp, and the initiation of a hemofilter. Continued work to reduce the occurrence of emboli is warranted.

Variation in arterial inflow temperature: a regional quality improvement project.

Peer-reviewed evidence (Class IIa, Level B) suggests that arterial blood temperature should be limited to 37 degrees C during cardiopulmonary bypass. We implemented a regional quality improvement initiative to reduce regional variability in our performance around this recommendation at four northern New England medical centers between January 2006 and June 2010. Cardiovascular perfusionists at four medical centers collaborated by conference calls regarding blood temperature management. Evidence from the recommendations were reviewed at each center, and strategies to prevent hyperthermia and to improve performance on this quality measure were discussed. Centers submitted data concerning highest arterial blood temperatures among all isolated coronary artery bypass grafting procedures between 2006 through June 2010. Scope and focus of local practice changes were at the discretion of each center. The timing of each center's quality improvement initiatives was recorded, and adherence to thresholds of 37 degrees C and 37.5 degrees C were analyzed. Data were collected prospectively through our regional perfusion registry. Data were available for 4909 procedures (1645 before interventions, 3264 after interventions). Prior to the quality improvement interventions, 90% of procedures had elevated arterial line temperatures (37 degrees C or more), and afterwards it was 69% (p < .001) for an absolute difference of 21%. Prior to the intervention, 53% of procedures had temperatures beyond a threshold of 37.5 degrees C versus 19% subsequent to interventions, for an absolute difference of 34% (p < .001). This regional effort to reduce patient exposure to elevated arterial line temperatures resulted in a significant sustained reduction in high arterial outflow temperatures at three of the four centers. A regional registry provides a means for assessing performance against evidence-based recommendations, and evaluating short and long-term success of quality improvement initiatives.

Rationalising the treatment of anaemia in cardiac surgery: short and mid-term results from a local quality improvement initiative.

BACKGROUND: Transfusion of red blood cells, while often used for treating blood loss or haemodilution, is also associated with higher infection rates and mortality. The authors implemented an initiative to reduce variation in the number of perioperative transfusions associated with cardiac surgery. METHODS: The authors examined patients undergoing non-emergent cardiac surgery at a single centre from the third quarter 2004 to the second quarter 2007. Phase I focused on understanding the current process of managing and treating perioperative anaemia. Phase II focused on (1) quality-improvement project dissemination to staff, (2) developing and implementing new protocols, and (3) assessing the effect of subsequent interventions. Data reports were updated monthly and posted in the clinical units. Phase III determined whether reductions in transfusion rates persisted. RESULTS: Indications for transfusions were investigated during Phase II. More than half (59%) of intraoperative transfusions were for low haematocrit (Hct), and 31% for predicted low Hct during cardiopulmonary bypass. 43% of postoperative transfusions were for low Hct, with an additional 16% for failure to diurese. The last Hct value prior to transfusion was noted (Hct 25-23, p=0.14), suggestive of a higher tolerance for a lower Hct by staff surgeons. Intraoperative transfusions diminished across phases: 33% in Phase I, 25.8% in Phase II and 23.4% in Phase III (p<0.001). Relative to Phase I, postoperative transfusions diminished significantly over Phase II and III. CONCLUSIONS: We report results from a focused quality-improvement initiative to rationalise treatment of perioperative anaemia. Transfusion rates declined significantly across each phase of the project.

Transforming administrative data into real-time information in the Department of Surgery.

BACKGROUND: Cardiothoracic surgical programmes face increasingly more complex procedures performed on evermore challenging patients. Public and private stakeholders are demanding these programmes report process-level and clinical outcomes as a mechanism for enabling quality assurance and informed clinical decision-making. Increasingly these measures are being tied to reimbursement and institutional accreditation. The authors developed a system for linking administrative and clinical registries, in real-time, to track performance in satisfying the needs of the patients and stakeholders, as well as helping to drive continuous quality improvement. METHODS: A relational surgical database was developed to link prospectively collected clinical data to administrative data sources at Dartmouth-Hitchcock Medical Center. Institutional performance was displayed over time using process control charts, and compared with both internal and regional benchmarks. RESULTS: Quarterly reports have been generated and automated for five surgical cohorts. Data are displayed externally on our dedicated website, and internally in the cardiothoracic surgical office suites, operating room theatre and nursing units. Monthly discussions are held with the clinical staff and have resulted in the development of quality-improvement projects. CONCLUSIONS: The delivery of clinical care in isolation of data and information is no longer prudent or acceptable. The present study suggests that an automated and real-time computer system may provide rich sources of data that may be used to drive improvements in the quality of care. Current and future work will be focused on identifying opportunities to integrate these data into the fabric of the delivery of care to drive process improvement.

Cardiopulmonary bypass recommendations in adults: the northern New England experience.

Using a regional cardiopulmonary bypass (CPB) registry, we compared the practice of CPB at eight northern New England institutions to recently published recommendations. We examined CPB practice among 3597 adult patients undergoing isolated coronary artery bypass grafting surgery from January 2004 to June 2005. Registry variables were used to compare regional CPB practice to recommendations on topics of neurologic protection (pH management, avoidance of hyperthermia, minimizing return of pericardial suction blood, aortic assessment, arterial line filtration), maintenance of euglycemia, reduction of hemodilution, and attenuation of the inflammatory response. We report overall regional practice (regional minimum, maximum). All centers used alpha-stat pH management and arterial line filters. Avoidance of hyperthermia (temperature < 37degrees C) was achieved during 23.4% of procedures (regional minimum, 1.5%; maximum, 83.2%). Minimizing return of pericardial suction blood was achieved in 23.7% of cases (0.7%, 93.6%). Aortic assessment was performed during 45.7% of procedures (1.3%, 98.9%). Maintenance of euglycemia (< 200 mg/dL) was accomplished in 82.7% (57.1%, 97.9%) of cases. Hemodilution (hematocrit < 23% on CPB) was lower for men 32.4% (20.6%, 52.3%) than women 77.9% (64.7% 88.9%). Men were less likely to receive red blood cell transfusions in the operating room (11.0%; 1.8%, 20.9%) than women (54.6%; 30.1%, 70.6%). In an effort to attenuate the inflammatory response, surface coated circuits were used in 83.3% of procedures (8.8%, 100%). During this time, gaps existed between regional CPB practice and recently published recommendations. We continue to prospectively measure CPB practice relating to these recommendations to monitor and improve the care provided to our patients.

Intraoperative red blood cell transfusion during coronary artery bypass graft surgery increases the risk of postoperative low-output heart failure.

BACKGROUND: Hemodilutional anemia during cardiopulmonary bypass (CPB) is associated with increased mortality during coronary artery bypass graft (CABG) surgery. The impact of intraoperative red blood cell (RBC) transfusion to treat anemia during surgery is less understood. We examined the relationship between anemia during CPB, RBC transfusion, and risk of low-output heart failure (LOF). METHODS AND RESULTS: Data were collected on 8004 isolated CABG patients in northern New England between 1996 and 2004. Patients were excluded if they experienced postoperative bleeding or received > or = 3 units of transfused RBCs. LOF was defined as need for intraoperative or postoperative intra-aortic balloon pump, return to CPB, or > or = 2 inotropes at 48 hours. Having a lower nadir HCT was also associated with an increased risk of developing LOF (adjusted odds ratio, 0.90; 95% CI, 0.82 to 0.92; P=0.016), and that risk was further increased when patients received RBC transfusion. When adjusted for nadir hematocrit, exposure to RBC transfusion was a significant, independent predictor of LOF (adjusted odds ratio, 1.27; 95% CI, 1.00 to 1.61; P=0.047). CONCLUSIONS: In this study, we observed that exposure to both hemodilutional anemia and RBC transfusion during surgery are associated with increased risk of LOF, defined as placement of an intraoperative or postoperative intra-aortic balloon pump, return to CPB after initial separation, or treatment with > or = 2 inotropes at 48 hours postoperatively, after CABG. The risk of LOF is greater among patients exposed to intraoperative RBCs versus anemia alone.

Highest core temperature during cardiopulmonary bypass and rate of mediastinitis.

Temperature control during cardiopulmonary bypass (CPB) may be related to rates of bacterial infection. We assessed the relationship between highest core temperature during CPB and rates of mediastinitis in 6955 consecutive isolated coronary artery bypass graft (CABG) procedures in northern New England. The overall rate of mediastinitis was 1.1%. The association between highest core temperature and mediastinitis was different for diabetics than for nondiabetics. A multivariate model showed that there was a significant interaction between diabetes and temperature in their association with mediastinitis (p=0.015). Diabetic patients showed higher rates of mediastinitis as highest core temperature increased, from 0.7% in the < or = 37 degrees C group to 3.3% in the > or = 38 degrees C group (p(trend) = 0.002). Adjusted rates were similar. Nondiabetic patients did not show this trend (p(trend) = 0.998). Among diabetic patients, a peak core body temperature > 37.9 degrees C during CPB is a significant risk factor for development of mediastinitis. Avoidance of higher temperatures during CPB may lower the risk of mediastinitis for diabetic patients undergoing CABG surgery.

Lowest core body temperature and adverse outcomes associated with coronary artery bypass surgery.

To examine the effect of lowest core body temperature on adverse outcomes associated with coronary artery bypass graft (CABG) surgery, data were collected on 7134 isolated CABG procedures carried out in New England from 1997 to 2000. Excluded from the analysis were patients with pump times < 60 and > 120 min and those operated upon using continuous warm cardioplegia. Data for lowest core temperature were divided into quartiles for analysis ( < 31.4 degrees C, 31.5-33.1 degrees C, 33.2-34.3 degrees C, and 2 34.4 degrees C). Patients with lower core body temperature on cardiopulmonary bypass (CPB) had higher in-hospital mortality rates. Crude mortality rates were 2.9% in the < or = 31.4 degrees C group, 2.1% in the 31.5-33.1 degrees C group, 1.3% in the 33.2-34.3 degrees C group and 1.2% in the > or = 34.4 degrees C group. The trend toward higher mortality as core temperature decreased was statistically significant (P(trend) < 0.001). Adjustment for differences in patient and disease characteristics did not significantly change the results and the test of trend remained significant (p < 0.001). Rates of perioperative stroke were somewhat lower in the colder groups. Rates in the two colder groups were 0.9% compared with 1.6% and 1.4% in the warmer groups (P(trend) = 0.082). This remained a marginal but significant trend after adjustment for possible confounding factors (p = 0.044). Low core body temperatures on CPB are associated with higher rates of in-hospital mortality among isolated CABG patients. Rates of intra- or postoperative use of an intra-aortic balloon pump are also higher with lower core temperatures. We concluded that temperature management strategy during CABG surgery has an important effect on patient outcomes.