The neglected perioperative population of undiagnosed diabetics - a retrospective cohort study.

BACKGROUND: Diabetes is known to increase morbidity and 30-day mortality in adults undergoing non-cardiac surgery, but longer term outcomes are less studied. This study was done to explore how undiagnosed and known diabetes affect 30-day and one-year morbidity and mortality outcomes. The secondary aim was to study the prevalence of undiagnosed diabetics in our perioperative Asian surgical population. METHODS: A retrospective cohort study of 2106 patients aged > 45 years undergoing non-cardiac surgery in a single tertiary hospital was performed. Undiagnosed diabetics were identified (HbA1c ≥6.5% or fasting blood glucose ≥126 mg/dL) and relevant demographic, clinical and surgical data were analyzed to elicit the relationship to adverse outcomes. Univariate analysis was first performed to identify significant variables with p-values ≤0.1, which were then analyzed using multiple logistic regression to calculate the adjusted odds ratio. RESULTS: The prevalence of undiagnosed diabetes was 7.4%. The mean and median HbA1c of known diabetics were 7.9 and 7.5%, while the mean and median HbA1c for undiagnosed diabetics were 7.2 and 6.8% respectively. 36.4% of known diabetics and 20.5% of undiagnosed diabetics respectively had a random blood glucose > 200 mg/dL. Undiagnosed diabetics had a three-fold increase in 1-year mortality compared to non-diabetics (adjusted OR 3.46(1.80-6.49) p < 0.001) but this relationship was not significant between known and non-diabetics. Compared to non-diabetics, known diabetics were at increased risks of new-onset atrial fibrillation (aOR 2.48(1.01-6.25) p = 0.047), infection (aOR 1.49(1.07-2.07) p = 0.017), 30-day readmission (aOR 1.62(1.17-2.25) p = 0.004) and 30-day mortality (aOR 3.11(1.16-8.56) p = 0.025). CONCLUSIONS: Although undiagnosed diabetics have biochemically less severe disease compared to known diabetics at the point of testing, they are at a one-year mortality disadvantage which is not seen among known diabetics. This worrying trend highlights the importance of identifying and treating diabetes. Congruent to previous studies, known diabetics have higher morbidity and 30-day mortality compared to non-diabetics.

Experiential learning improves the learning and retention of endotracheal intubation.

CONTEXT: Simulators provide an effective platform for the learning of clinical motor skills such as endotracheal intubation, although the optimal learning technique remains unidentified. We hypothesised that, for novices, experiential learning would improve the learning and retention of endotracheal intubation compared with guided learning. METHODS: Year 4 medical students were randomised to either guided or experiential learning. Students in the guided group were taught using the conventional step-by-step technique. Students in the experiential group had to work out the correct technique for intubation on their own. Both groups had further opportunities to intubate manikins and patients during their postings. The students were recalled 3, 6, 9 and 12 months later, and their intubation skills assessed in four major categories: equipment preparation; intubation technique; successful intubation, and placement confirmation. RESULTS: A total of 210 students (107 guided, 103 experiential) participated in the study. At 3 months, 64.5% of the students in the experiential group successfully intubated the manikin, compared with 36.9% in the guided group (P < 0.001). The experiential group also had higher overall scores, signifying quality of intubation attempts, at 3 months (79% versus 70%; P < 0.001). Success rates and overall scores for both groups were comparable at 6 and 9 months, but were better in the experiential group at 12 months. Success rates improved with time, reaching 86% at 12 months. CONCLUSIONS: Novices learned and retained the skill of endotracheal intubation better with experiential learning. This study suggests that experiential learning should be adopted for the teaching of endotracheal intubation and that refresher tuition at 3-monthly intervals will prevent the decay of this skill in infrequent users.

Comparison of mini-cardiopulmonary bypass system with air-purge device to conventional bypass system.

BACKGROUND: Although mini-cardiopulmonary bypass systems reduce inflammation, hemodilution, and transfusion requirements, the problem of air entrainment and embolization into the system has limited its use. Newer systems incorporate an air purge to address this problem. We compared the benefits and possible risks in using the newer mini-cardiopulmonary bypass system with those for conventional cardiopulmonary bypass. METHODS: Data of 60 patients who underwent cardiac surgery with a newer mini-cardiopulmonary bypass system incorporating an air purge from August 2005 to July 2006 (group A) were retrospectively collected and compared with that of 60 matched patients who underwent cardiac surgery with conventional cardiopulmonary bypass during the same period (group B). Matching criteria were prebypass hematocrit, body surface area, age, and surgical procedure. RESULTS: Demographic and background data were similar for both groups. There were no detectable episodes of air embolism. Patients in group A had higher initial and nadir hematocrits during cardiopulmonary bypass and received fewer transfusions. However, postoperative blood loss and transfusion requirements were similar in both groups. Episodes of low indexed flows during cardiopulmonary bypass commonly occurred in group A, and this was associated with a greater than 50% decrease in urine output and lower mixed venous oxygen saturations (58% +/- 6% versus 68% +/- 5%) as compared with group B. There were no differences in clinical outcomes. CONCLUSIONS: The newer mini-cardiopulmonary bypass system addressed the problem of air embolization. It preserved hematocrit and reduced transfusion during cardiopulmonary bypass, but did not improve outcomes postoperatively. It is unclear whether these benefits outweigh the potential risk of hypoperfusion associated with its use.

Preoperative statin therapy does not reduce cognitive dysfunction after cardiopulmonary bypass.

OBJECTIVE: The purpose of this study was to determine if patients receiving statin therapy before coronary artery bypass grafting surgery would have less cognitive dysfunction after cardiopulmonary bypass as a consequence of a diminished inflammatory response. DESIGN: Retrospective observational study of patients undergoing coronary artery bypass grafting surgery. SETTING: Referral center for cardiothoracic surgery at a university hospital. PARTICIPANTS: Four hundred forty patients undergoing coronary artery bypass grafting surgery with cardiopulmonary bypass. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Thirty-five percent of patients received statins in the preoperative period. Multivariable analysis revealed no effect of preoperative statin therapy on cognitive function (p = 0.67). Post hoc analysis revealed that statin therapy at hospital discharge was associated with less improvement in cognitive performance at 6 weeks after surgery (p = 0.011). No significant differences were found between statin therapy groups in either range or maximum value of any of the cytokines (p > 0.05). CONCLUSIONS: Preoperative statin therapy did not decrease the inflammatory response to cardiopulmonary bypass or the cognitive dysfunction commonly seen after cardiac surgery.

Aortic atheroma burden and cognitive dysfunction after coronary artery bypass graft surgery.

BACKGROUND: Neurocognitive dysfunction (NCD) after coronary artery bypass graft (CABG) surgery is a common problem. Atherosclerotic disease of the aorta is a known risk factor for stroke after cardiac surgery, but its relationship to NCD is unclear. This study investigates the relationship between aortic atherosclerotic disease and NCD after CABG. PATIENTS AND METHODS: Patients undergoing primary elective CABG were enrolled in an ongoing investigation of NCD after CABG. Intraoperative transesophageal echocardiography (TEE) of the thoracic aorta was performed and analyzed off-line to quantify atheroma burden. Neurocognitive evaluation was performed, both preoperatively and at 6 weeks after surgery. Multivariable linear regression (controlling for age, years of education, and base line cognitive index) was used to determine the relationship between NCD and atheroma burden in the ascending, arch, and descending aorta. RESULTS: One hundred sixty-two patients who had a complete neurocognitive evaluation and adequate TEE images were studied. No significant relationship was found between NCD and atheroma burden in the ascending (p = 0.22), arch (p = 0.89) or descending aorta (p = 0.64). CONCLUSIONS: Although the etiology of NCD is likely multifactorial, our results suggest that aortic atherosclerosis may not be the primary factor in the pathogenesis of post-CABG cognitive changes.

Preliminary report on the interaction of apolipoprotein E polymorphism with aortic atherosclerosis and acute nephropathy after CABG.

BACKGROUND: Renal dysfunction is a serious complication of cardiac surgery that is highly associated with short- and long-term adverse outcome. While the apolipoprotein E (APOE) epsilon4 allele has been linked to the occurrence of both postcardiac surgery acute renal injury (epsilon4 favorable) and ascending aortic arteriosclerosis (epsilon4 unfavorable), the role of epsilon4 in the relationship between these two conditions is unknown. We hypothesized that patients with and without the epsilon4 allele (E4/non-E4) would have different associations between atheroma burden and postoperative renal dysfunction. METHODS: Ascending, arch, and descending aorta atheromatous burden and APOE status were evaluated for 130 coronary bypass patients. Multivariable analyses were performed for aortic regions to assess the relationship of atheroma burden and APOE epsilon4 status with peak in-hospital postoperative serum creatinine. All p < 0.05 were considered significant. RESULTS: We found an interaction between E4 status (E4/non-E4; 24/106) and atheroma burden, with a much greater predicted peak in-hospital postoperative serum creatinine for increases in ascending aorta atheroma load for non-E4 patients versus E4 patients (beta coefficient -0.13; p = 0.002). We also confirmed the association between ascending aorta atheroma and peak creatinine (beta coefficient 0.11; p = 0.0008), after controlling for E4 status, preoperative creatinine, and the E4-atheroma interaction. CONCLUSIONS: Equivalent ascending aortic atheroma burden is associated with a greater susceptibility to postoperative renal injury among patients undergoing cardiac operation who lack the APOE epsilon4 allele. Findings may be attributable to APOE-related differences in inflammation, susceptibility to atheroma detachment (eg, during operative aortic manipulation), or renal vulnerability to embolic injury.

Prediction of excessive bleeding after coronary artery bypass graft surgery: the influence of timing and heparinase on thromboelastography.

OBJECTIVE: To compare the ability of thromboelastography, when done at either 10 or 60 minutes after protamine reversal of heparin, to predict excessive bleeding after coronary artery bypass graft (CABG) surgery and to investigate, with the use of heparinase, whether heparin contamination was responsible for the difference, if any. DESIGN: Prospective study. SETTING: University hospital, single institution. PARTICIPANTS: Patients undergoing elective CABG surgery (n = 40). INTERVENTIONS: Blood samples for thromboelastography and routine coagulation tests were collected before induction of anesthesia and at 10 and 60 minutes after protamine reversal of heparin. Blood loss and blood product use were recorded postoperatively. MEASUREMENTS AND MAIN RESULTS: Of 40 patients undergoing elective CABG surgery, 10 fulfilled the criteria for excessive postoperative bleeding. The sensitivity of thromboelastography to identify patients who bled was better at 60 minutes than at 10 minutes after protamine reversal of heparin (100% v 70%). There was greater specificity (83% v 40% at 10 minutes; 73% v 20% at 60 minutes) and positive predictive value (58% v 28% at 10 minutes; 55% v 29% at 60 minutes) when heparinase was added. At both times, thromboelastography showed only moderate correlation with total blood loss and the use of fresh frozen plasma or platelets or both. Conventional coagulation tests did not predict excessive postoperative bleeding. CONCLUSION: This study suggests that timing and the use of heparinase influence the predictive ability of thromboelastography, but its usefulness as a sole predictor of post-CABG surgery bleeding is limited.

Mitral flow propagation velocity identifies patients with abnormal diastolic function during coronary artery bypass graft surgery.

UNLABELLED: Flow propagation velocity (Vp) is a new method of assessing left ventricular (LV) diastolic (D) function that seems to be insensitive to heart rate and preload changes. We hypothesized that Vp <50 cm/s identifies patients with D dysfunction and that Vp provides an assessment of D function when standard Doppler techniques are uninterpretable. We conducted a prospective Doppler echocardiographic assessment of D function in 63 patients undergoing coronary artery bypass graft surgery. Doppler derivatives of mitral inflow and pulmonary vein flow profiles as well as isovolumic relaxation time were compared with Vp before and after cardiopulmonary bypass. A Valsalva maneuver was used to decrease preload. All patients with D dysfunction had Vp <50 cm/s. A Valsalva maneuver did not affect Vp. Vp remained a reliable measure of LV D function when mitral flow profiles could not be determined because of changes in heart rate and rhythm. LV filling patterns did not change significantly after cardiopulmonary bypass. We conclude that Vp is a simple measure of D function during coronary artery bypass graft surgery that correlates with standard, load-dependent Doppler echocardiographic techniques to identify D dysfunction. Vp <50 cm/s identifies abnormal D function in this patient population. IMPLICATIONS: Mitral propagation velocity (Vp) is a simple, reproducible measure of diastolic function during coronary artery bypass graft surgery that correlates with standard Doppler echocardiographic techniques to identify dysfunction in the setting of a rapid heart rate or variable preload. Vp <50 cm/s identifies abnormal diastolic function in this patient population.