Muhammed Kurt

Predictors and outcome of ICU readmission after cardiac surgery.

OBJECTIVE Readmission to the intensive care unit (ICU) after cardiac surgery is associated with higher costs and may be correlated with an increased mortality. We wanted to evaluate predictors of ICU readmission and to analyze the outcome of those patients. METHODS 3523 patients who underwent CABG and/or valve surgery between 2004 and 2007 were reviewed retrospectively. The reasons for readmission and the postoperative course were analyzed. Furthermore, perioperative risk factors for readmission were determined by multivariate regression analysis. RESULTS Of the 3374 patients discharged from the ICU, 5.9 % (198) of patients required a second stay in the intensive care (group r). The readmission rate was 4.8 % following CABG and 8.9 % following valve +/- CABG ( P < 0.05). The mean interval from ICU discharge to readmission was 3.3 +/- 6.2 days. Of the patients who were not readmitted, 1.3 % died in hospital, compared to 14.4 % in group r ( P < 0.05). After readmission, the mean length of stay in the ICU and in hospital was 7.1 +/- 5.9 and 21.3 +/- 11.1 days (3.1 +/- 1.2 and 13.1 +/- 5.1 days for all other patients [ P < 0.05]). Main reasons for readmission were respiratory failure (59 %), cardiovascular instability (25 %), renal failure (6.5 %), cardiac tamponade/bleeding (6 %), gastrointestinal complications (2 %) and sepsis (1.5 %). Multivariate logistic regression analysis revealed that preoperative renal failure, mechanical ventilation > 24 h, reexploration for bleeding and low cardiac output state were independent predictors for readmission. CONCLUSIONS Patients after valve/combined surgery are more likely to require readmission to the ICU. Respiratory complications were the most common reasons for readmission. To reduce the readmission rate, it is necessary to treat cardio-respiratory problems early, particularly in patients showing predictive risk factors.

Intraaortic balloon pumping in patients with right ventricular insufficiency after cardiac surgery: parameters to predict failure of IABP Support.

BACKGROUND The indications for intra-aortic balloon pump (IABP) in the case of a failing right ventricle after operations with extracorporeal circulation (ECC) are still discussed controversially. We investigated the benefit of IABP in patients with a predominantly right ventricular dysfunction after ECC. Additionally, we wanted to identify early and easily available prognostic markers for outcome in all patients receiving IABP support. PATIENTS AND METHODS Between 1/2004 and 1/2008, 4550 patients underwent cardiac surgical procedures with ECC, 223 of whom (4.9 %) had an IABP inserted intra- or postoperatively (group 1). 79 of these patients were treated intraoperatively with IABP for early postoperative low cardiac output syndrome (LCOS) characterized by predominantly right ventricular failure (RV group). Clinical data and hemodynamic variables were recorded perioperatively. Multiple potential markers of mortality and postoperative complications were analyzed statistically, especially with regard to their predictive ability. RESULTS 68 % of all IABP patients were successfully weaned from IABP support and 63 % survived to hospital discharge. In the RV group, cardiac index (CI) and mean arterial pressure (MAP) increased (CI 1.8 +/- 0.2 to 2.8 +/- 0.2, MAP 53 +/- 10 to 73 +/- 8, P < 0.05) within 1 hour after IABP, whereas central venous pressure (CVP) and pulmonary artery wedge pressure (PAWP) decreased ( P < 0.05). 59 patients in the RV group (75 %) could be weaned from IABP successfully and 69 % survived to hospital discharge. Serum lactate of more than 11 mmol/L in the first 10 hours of IABP support predicted a 100 % mortality. A base deficit of more than 12 mmol/L, mean arterial pressure less than 55 mmHg, urine output of less than 50 ml/h for 2 hours, and dose of epinephrine or norepinephrine of more than 0.4 mg/kg/min were other highly predictive prognostic markers. Furthermore, multivariate analysis showed that patients with a left atrial pressure > 17 mmHg or a mixed venous saturation (SVO (2)) < 65 % had poor outcomes. CONCLUSIONS In patients with IABP support for postcardiotomy cardiogenic shock, elevated serum lactate, elevated base deficit, hypotension, oliguria and large vasopressor doses are all predictors of mortality. In these patients, the use of another mechanical assist device should be considered in good time. Our study additionally shows that LCOS caused by predominantly right ventricular failure - particularly after CABG - may be an additional indication for IABP.

Detection and duration of aspirin resistance after coronary artery bypass grafting

A spirin resistance is associated with a significant increase in major adverse cardiovascular events. We have previously reported an insufficient antiplatelet effect of aspirin in most patients after coronary artery bypass grafting (CABG). Nevertheless, the duration of aspirin resistance after CABG remains unknown, and the suitability of available tools to discriminate those with reduced response to aspirin is controversial. This work determined the antiplatelet effect of aspirin at the time of CABG and 6 months later and examined the reliability of different methods for the diagnosis of aspirin resistance.

The Impact of Pre- and Postoperative Renal Dysfunction on Outcome of Patients Undergoing Coronary Artery Bypass Grafting (CABG)*

OBJECTIVE Acute changes in renal function after elective coronary bypass surgery represent a challenging clinical problem. In this study, we evaluated perioperative risk factors for the development of postoperative renal dysfunction (PRD), and the impact of such an event on the perioperative course. Additionally, we investigated the influence of preoperatively mildly increased serum creatinine on perioperative mortality and morbidity. METHODS We retrospectively analyzed data of 2511 patients undergoing isolated CABG between 2004 and 2007 with a preoperative serum creatinine < or = 2.2 mg/dL. There were 592 patients with a preoperative serum creatinine of between 1.4 and 2.2 mg/dl (mild renal dysfunction group) and 1919 patients with a serum creatinine < 1.4 mg/dl. Perioperative risk factors for PRD were analyzed by multivariate regression analysis. RESULTS Global in-hospital mortality was 3.1 %.The incidence of PRD was 6.2 %. Mortality for patients who had PRD was 7.8 vs. 2.9 % for patients who did not ( P < 0.05). PRD increased the length of hospital stay by 3.7 days (12.2 vs. 15.9; P < 0.05). Multivariate logistic regression identified the following variables as independent predictors of PRD: age, angina class III/IV, diabetes mellitus, prolonged cardiopulmonary bypass time, and preoperative serum creatinine. With regard to preoperative renal function, we found that operative mortality was higher in the mild renal dysfunction group (5.7 % vs. 2.5 %; P < 0.05). New dialysis/hemofiltration (5.1 % vs. 1.2 %; P < 0.05) and postoperative stroke (5.1 % vs. 1.6 %; P < 0.05) were also more common in these patients. CONCLUSIONS Mild renal dysfunction preoperatively is an important predictor of outcome after CABG. In these patients, PRD dramatically increases mortality, morbidity and length of hospital stay.

Early reintubation after cardiac operations: impact of nasal continuous positive airway pressure (nCPAP) and noninvasive positive pressure ventilation (NPPV).

BACKGROUND Due to an increasing number of comorbidities there is still a significant incidence of respiratory failure after primary postoperative extubation in patients who undergo cardiosurgery. We wanted to study whether nCPAP could improve pulmonary oxygen transfer and avoid the necessity for reintubation after cardiac surgery. Additionally, we compared this protocol to noninvasive positive pressure ventilation (NPPV). PATIENTS AND METHODS Over a period of 3 years we analyzed all patients who were extubated within 12 hours after cardiac surgery, and in whom pulmonary oxygen transfer (PaO₂/FIO₂) deteriorated without hypercapnia so that all these patients met predefined criteria for reintubation. There were three groups of patients: A = patients required immediate reintubation (n = 125); B = patients had nCPAP with intermittent mask CPAP (n = 264); and C = patients had NPPV (n = 36). RESULTS 25.8 % of patients in Group B and 22.2 % of patients in Group C were also intubated after a period of CPAP or NPPV. All other patients of Groups B and C could be weaned from these devices (B: 33.4 ± 5.8 hours, C: 26.2 ± 4.2 h; P < 0.05) and were well oxygenated using a face mask at ambient pressures (PaO₂/FIO₂: B: 136 ± 12, C: 141 ± 12). In Group A, we found a higher mortality (8.8 %) than in Group B (4.2 %) and Group C (5.6 %). The ICU stay and in-hospital stay were significantly prolonged in Group A. The incidence of pulmonary infections (A: 24 %, B: 10.6 %, C: 13.8 %; P < 0.05) and the need for catecholamines were significantly increased in Group A, whereas nCPAP patients suffered significantly more often from impaired sternal wound healing (A: 4.8 %, B: 8.3 %; P < 0.05). CONCLUSIONS We conclude that reintubation after cardiac operations should be avoided since nCPAP and NPPV are safe and effectively improve arterial oxygenation in the majority of patients with nonhypercapnic oxygenation failure. However, it is of great importance to pay special care to sternal wound complications in these patients.

Aspirin-induced platelet inhibition in patients undergoing cardiac surgery

Platelet function and response to pharmacological inhibition are altered by cardiac surgery. For example, aggregation is increased early after aortic valve replacement (AVR) and platelet response to aspirin is often insufficient after coronary artery bypass grafting (CABG). We hypothesized that the effect of aspirin administration after cardiac surgery might be impaired due to platelet activation. Therefore, the antiplatelet effect of aspirin was compared in patients (n = 20 per group) after CABG and AVR surgery (bileaflet prosthesis). Arachidonic acid-induced aggregation (turbidimetry) and thromboxane formation (radioimmunoassay) were determined before and 1, 5, and 10 days after surgery. In CABG-patients, antiplatelet treatment had been discontinued 10 days before surgery. Oral aspirin was started on day 1 after CABG. AVR-patients did not receive oral aspirin. Before surgery, platelet aggregation and thromboxane formation were significantly higher in patients with aortic stenosis. After CABG, thromboxane formation was not significantly changed from control values before surgery (66 ± 13% on day 10) despite oral aspirin treatment, whereas thromboxane formation in patients undergoing AVR significantly increased compared to values before surgery (216 ± 29% on day 10). In both groups of patients, 100 µmol/l aspirin in vitro largely inhibited platelet function before surgery, with markedly attenuated effects after surgery. In conclusion, thromboxane formation increased after AVR but not after CABG. The antiplatelet effect of aspirin, therefore, may be impaired after CABG by increased platelet activity. An additional in vitro “resistance” of platelets was seen after both CABG and AVR.

A novel function of FoxO transcription factors in thrombin-stimulated vascular smooth muscle cell proliferation

Thrombin exerts coagulation-independent effects on the proliferation and migration of vascular smooth muscle cells (SMC). Forkhead box-O (FoxO) transcription factors regulate cell proliferation, apoptosis and cell cycle arrest, but a possible functional interaction between thrombin and FoxO factors has not been identified to date. In human cultured vascular SMC, thrombin induced a time-dependent phosphorylation of FoxO1 and FoxO3 but not FoxO4. This effect was mimicked by an activating-peptide (AP) for protease-activated receptor (PAR)-1, and abolished by a PAR-1 antagonist (SCH79797). APs for other PARs were without effect. FoxO1 and FoxO3 phosphorylation were prevented by the PI3 kinase (PI3K) inhibitor LY294002 while inhibitors of ERK1/2 (PD98059) or p38MAPK (SB203580) were ineffective. LY294002 moreover prevented thrombin-stimulated SMC mitogenesis and proliferation. FoxO1 and FoxO3 siRNA augmented basal DNA synthesis and proliferation of SMC. Nuclear content of FoxO proteins decreased time-dependently in response to thrombin, coincided with suppressed expression of the cell cycle regulating genes p21CIP1 and p27kip1 by thrombin. FoxO1 siRNA reduced basal p21CIP1 while FoxO3 siRNA attenuated p27kip1 expression; thrombin did not show additive effects. LY294002 restored p21CIP1 and p27kip1 protein expression. Immunohistochemistry revealed that human native and failed saphenous vein grafts were characterised by the cytosolic presence of p-FoxO factors in co-localisation of p21CIP1 and p27kip1 with SMC. In conclusion, thrombin and FoxO factors functionally interact through PI3K/Akt-dependent FoxO phosphorylation leading to expression of cell cycle regulating genes and ultimately SMC proliferation. This may contribute to remodelling and failure of saphenous vein bypass grafts.

Cardiac Valve Replacement in Patients with End-Stage Renal Failure: Impact of Prosthesis Type on the Early Postoperative Course

BACKGROUND It is still unclear whether biological or mechanical valves should be preferred in patients on chronic dialysis therapy. PATIENTS AND METHODS We retrospectively analyzed data from 104 patients (66.5 +/- 8.6 years) with end-stage renal failure (RF) who underwent aortic or mitral valve replacement between 2002 and 4/2008. Mechanical valves were implanted in 44 (42 %) patients and bioprostheses in 60 (58 %). The two groups were comparable with regard to preoperative data, age and incidence of additional CABG procedures. We studied in-hospital morbidity and mortality, major postoperative complications and length of ICU and hospital stay. Additionally, parameters predicting a poor outcome were analyzed with multivariate regression analysis. RESULTS The overall hospital mortality was 12.5 % and did not differ between the two groups (mechanical: 13.6 %, biological: 11.7 %, n. s.). In the postoperative course, duration of ventilation and ICU stay were similar, whereas hospital stay was significantly longer for patients with mechanical prostheses (19.5 +/- 5.4 vs. 15.6 +/- 4.1 days, P < 0.05). Mechanical valve patients had a significantly higher rate of postoperative cerebrovascular incidents (18.2 vs. 8.3 %, P < 0.05) and bleeding complications (15.9 vs. 11.7 %, P < 0.05). Reoperation, obesity, left ventricular ejection fraction < 30 % and previous neurological complications were independent predictors of hospital mortality. CONCLUSIONS Our results demonstrate that in patients with end-stage RF, the use of mechanical valves is associated with a significant risk of complications. Because of the poor overall survival of patients on dialysis, bioprosthesis degeneration will not be a limiting factor. Therefore, preference should be given to biological valves in these patients.

Abdominal complications following open-heart surgery : a report of 12 cases and review of the literature

Introduction — Abdominal complications following open-heart surgery remain serious events as the mortality is reported to be tremendously high.The clinical presentation, the diagnostic strategy and the therapeutic management varies.We reviewed all records of those patients who developed abdominal complications with surgical consequences during the last five years, recorded a complete follow-up and compared the findings to a current view of the literature. Patients and methods — Altogether 5720 patients underwent open-heart surgery at our institution between 1/98 and 12/02. Out of these 12 (10 men, 2 women) developed severe gastrointestinal complications with surgical consequences.The mean age was 73.17 ± 8.11 years. Seven patients underwent isolated coronary artery bypass grafting (CABG), two patients combined aortic valve replacement (AVR) and CABG, one isolated AVR, one mitral valve replacement (MVR) and yet another one combined MVR and CABG.The clinical records of all these patients were examined and a complete follow-up was recorded. Results — The duration of the entire cardiac operation was a mean of 212.67 ± 36.97 min, perfusion time 103 ± 29.32 min and myocardial ischaemic time 52.25 ± 24.56 min. Length of ICU-stay was between 1 and 5 days after cardiac surgery. Concerning gastrointestinal complications nine patients suffered from ischaemic intestinal disease, two from gastrointestinal ulcer bleeding and one from a preoperatively unknown bowel tumour with subsequent ileus. Four patients died in the immediate postoperative course, one patient within two years and seven patients show a satisfactory status at follow-up. Conclusions — A review from the literature shows an enormous mortality from abdominal complications following open-heart surgery.This was also found in our series.As many of these patients have a history of abdominal disease more attention should be paid to such anamnestic hints in the preparation before cardiac surgery. Hence we recommend early diagnostic measures and explorative laparotomy in doubtful situations in patients with positive anamnesis.

Predictors of postoperative complications in octogenarians undergoing cardiac surgery

OBJECTIVE Aim of the study was to clarify the impact of different pre- and perioperative conditions on outcome in octogenarians undergoing cardiac surgery. METHODS We retrospectively analyzed preoperative risk factors and intraoperative adverse events and studied in-hospital morbidity and mortality in 646 patients > or = 80 years of age (82.5 +/- 3.5 years) and in 6081 younger patients (70.3 +/- 3.4 years) who underwent cardiac surgery between 1/2001 and 12/2006. RESULTS Preoperatively, octogenarians suffered significantly more from arterial hypertension, renal failure, previous neurological problems, unstable angina and NYHA class IV than younger subjects. The incidence of combined valve and coronary procedures and of urgent operations was also significantly higher in patients > or = 80 years (27.7 % vs. 18.2 %, P < 0.05, and 7.3 % vs. 4.2 %, P < 0.05, respectively). In-hospital mortality was higher (7.4 % vs. 3.7 %, P < 0.05), and average ICU and total in-hospital stay was longer in the older age group. Postoperative complications occurred in 15 % of patients > or = 80 years compared to 7.6 % of patients < or = 79 years ( P < 0.05). NYHA class IV, female sex and preoperative renal failure correlated with perioperative morbidity. Multivariate analysis could identify urgent procedures, redo surgery, mitral valve surgery and prolonged cross-clamping times as predictors of mortality. CONCLUSIONS Cardiac surgery in octogenarians can be performed with an acceptable risk but an increased mortality and morbidity compared to younger patients. High-risk octogenarians, who require intensive perioperative management, should be identified to reduce the incidence of postoperative complications.