Impact of preoperative serum creatinine on short- and long-term mortality after cardiac surgery: a cohort study.

BACKGROUND: Preoperative renal insufficiency is an important predictor of mortality after cardiac surgery. This retrospective cohort study was designed to identify the optimal cut-off for baseline serum creatinine (bSCr) and estimated glomerular filtration rate (eGFR) to predict survival. Furthermore, we investigated the potential confounding effect of other perioperative risk indicators on short- and long-term survival. METHODS: Data of 9490 cardiac surgical patients were prospectively collected between 1997 and 2008 (follow up to 2010) at the Medical University Vienna. We identified bSCr cut-off values and calculated uni- and multivariate hazard models for short- and long-term survival and compared the results with a validation set from Zurich. The estimated survival curves defined a distinct period of increased mortality until 150 days. RESULTS: Cut-off values of >115 µmol litre(-1) for bSCr and ≤50 ml min(-1) for eGFR were identified. Increased bSCr, associated with higher mortality [hazard ratio (HR) 2.61, 95% confidence interval (CI) 2.43-2.80, P<0.0001], was present in 19.5% of patients and remained predictive for short- (HR 1.59, 95% CI 1.38-1.83, P=0.0027) and long-term survival (HR 1.46, 95% CI 1.32-1.62, P<0.0001) in the multivariate hazard models. A cut-off of >120 µmol litre(-1) for bSCr was determined for the validation set. Decreased eGFR was present in 23.6% (HR 2.86, 95% CI 2.67-3.06, P<0.0001). CONCLUSIONS: In our patients, increased bSCr was an independent predictor of mortality, which may critically influence risk evaluation and perioperative treatment guidance.

Cardiac output measurement by pulse dye densitometry in cardiac surgery.

Summary The aim of this study was to compare the accuracy of pulse dye densitometry with that of bolus thermodilution cardiac output measurement in patients before and after elective coronary artery bypass grafting. Twenty-eight patients were studied. Agreement between mean thermodilution and pulse dye densitometry cardiac output values was assessed by Bland-Altman analysis. Preoperative median [range] cardiac output was 3.87 [2.37-6.0] l.min(-1) by thermodilution, and 3.11 [1.7-5.45] l.min(-1) by pulse dye densitometry using indocyanine green 5 mg. Pulse dye densitometry underestimated cardiac output (mean bias - 0.42 l.min(-1)); the limits of agreement were +/- 1.91 l.min(-1), and mean error was 50.3%, indicating low precision. Preoperative median [range] cardiac output was 3.85 [2.2-6.0] l.min(-1) for bolus thermodilution cardiac output and 4.2 [2.0-7.2] l.min(-1) for pulse dye densitometry using indocyanine green 20 mg. Mean bias was + 0.566 l.min(-1), the limits of agreement were +/- 2.51 l.min(-1) and mean error was 60.9%. Postoperative cardiac output data were not analysed because pulse dye densitometry signals were low or absent in > 50% of the patients. We conclude that pulse dye densitometry using indocyanine green 5 mg or 20 mg is inaccurate in anaesthetised patients before coronary artery bypass surgery and cannot be used after surgery because of a high incidence of low pulse dye densitometry signal amplitudes.

Determinants of costs and resource utilization associated with open heart surgery.

AIMS: This study sought to determine the patient- and the therapy-related determinants of in-hospital costs for patients undergoing heart surgery at the University Hospital in Zurich. METHODS AND RESULTS: We performed a retrospective analysis of all adult cardiac surgical patients from the canton St. Gallen who were covered by a fixed fee arrangement (29,500 Swiss francs (19,470 Euro)) and referred to our institution during 1998. A total of 201 patients (143 (71%) male) with basic insurance were hospitalized in 1998 under the fixed fee arrangement. The mean age of the patients was 61.4 years (95% confidence intervals (CI): 60; 63). With the help of univariate analysis, the following pre-operative characteristics were found to be significantly associated with cost: age (P<0.001), pre-operative cardiac diagnosis (coronary vs valvular heart disease) (P<0.001) and EuroSCORE (P<0.0001). A significant correlation was also found between intra-operative variables and costs (P<0.0001) as well as between postoperative variables and costs (P<0.0001). A linear regression model based on EuroSCORE, operation time and postoperative infection status is able to predict costs for patients (all P -values <0.0001, except for P<0.05 for operation time, R(2)=0.565). CONCLUSIONS: These results suggest that both pre-operative (patient related) and intra-operative (therapy- and patient-related) variables are predictors of costs in cardiac surgical patients.

Indications and impact of postoperative transesophageal echocardiography in cardiac surgical patients.

OBJECTIVE: Transesophageal echocardiography (TEE) has gained widespread acceptance among intensivists as a tool to facilitate decision-making in the management of critically ill patients. This observational study analyzes the indications and impact of TEE and the outcome in patients following cardiac surgery. DESIGN: Standardized reports containing indication, main diagnosis, and impact on patient management were completed during TEE. SETTING: Intensive care unit in a university hospital. PATIENTS: Postoperative cardiac surgery patients requiring TEE. INTERVENTION: TEE in sedated and mechanically ventilated patients. MEASUREMENTS AND RESULTS: Reports were obtained in 301 adult patients between June 1996 and June 2000. Indications were postoperative control of left ventricular function in 102 (34%) cases; unexplained, sudden hemodynamic deterioration in 89 (29%); suspicion of pericardial tamponade in 41 (14%); cardiac ischemia in 26 (9%); and "other" in 43 (14%). In 136 patients (45%), a new diagnosis was established or an important pathology was excluded. Pericardial tamponade was diagnosed in 34 cases (11%) and excluded in 36 cases (12%). Other diagnoses included severe left ventricular failure, large pleural effusion, and others. Therapeutic impact was found in 220 cases (73%): change of pharmacologic treatment and/or fluid therapy in 118 cases (40%), resternotomy in 43 (14%), no reoperation necessary in 39 (13%), and various in 20 (7%). No impact was found in 81 cases (27%). In a subgroup of patients in whom preoperative risk scores were evaluated, the indication for a postoperative TEE was significantly associated with a prolonged stay in the intensive care unit: 7 (5.6, 8.4) days vs. 1 (0.8, 1.2) day (median, [95% confidence interval]) (p <.0001), more neurologic complications (18/137 = 13.1% vs. 21/680 = 3.0%) (p <.0001), and increased mortality (34/153 = 22.2% vs. 18/709 = 2.5%) (p <.0001). Corrected for preoperative risk scores, these differences were still significant. CONCLUSION: Although TEE provided important findings and therapeutic impact in postoperative cardiac surgical patients, patients with comparable preoperative risk who had postoperative TEE examinations had a significantly worse outcome than those without the need for postoperative TEE.

Monitoring level of sedation with bispectral EEG analysis: comparison between hypothermic and normothermic cardiopulmonary bypass.

The level of sedation of 28 patients undergoing elective coronary artery bypass grafting with fentanyl-propofol anaesthesia was monitored with bispectral analysis (BIS), spectral edge frequency, and band power of the electroencephalogram. Fourteen patients underwent hypothermic cardiopulmonary bypass (CPB) (32 degrees C, group H), and 14 normothermic CPB (group N). The level of sedation was measured with Observer's Assessment of Alertness/Sedation Score and with Ramsay Sedation Score. BIS was the only EEG measurement that paralleled the clinical course of the patients' sedation level. Values (median, 95% confidence intervals (CI)) changed significantly over time in both groups (P<0.0001). In group H, BIS decreased from 97 (95, 99) the day before surgery to 48 (44, 52) after tracheal intubation, to 46 (41, 52) before going off CPB, to 91 (85, 97) immediately before extubation. In group N, values were 93 (91, 97) the day before surgery, 53 (47, 59) after tracheal intubation, 48 (43, 53) before going off CPB, and 90 (84, 96) before extubation. During CPB, BIS values were significantly different between the two groups. Group H had a median of 41 (95% CI, 39, 42), and group N had a median of 49 (95% CI, 48, 51, P<0.0001). Peak values of all other processed EEG parameters during anaesthesia and surgery overlapped with values from the day before, when patients had no sedating medication, and these values did not correlate to the patients' course of sedation during the study. There was no explicit recall of the surgery in either group. During the phases of anaesthesia and surgery without CPB, the progression of BIS levels was comparable with previously published data for non-cardiac surgery. During normothermic CPB, the highest BIS values were close to values representing insufficient depth of sedation. It remains to be elucidated whether the much lower BIS values in the hypothermic group were solely a result of brain cooling or if increased serum propofol concentrations, because of slowed pharmacodynamics during hypothermia, also contributed.

Transoesophageal echocardiography in cardiac and vascular surgery: implications and observer variability.

Transoesophageal echocardiography (TOE) has gained widespread acceptance among cardiac anaesthetists as a tool to facilitate peri-operative decision-making. This observational study analyses the impact of TOE and its inter-observer variability on intra-operative patient management during cardiac and major vascular surgery. From June 1996 to December 1998, standardized reports were obtained from 11 anaesthetists in 1891 adult cardiac and vascular surgery patients undergoing routine biplane or multiplane TOE. Inter-observer variability and the difference between variables of interest were tested using the chi-squared test or factorial analysis of variance as appropriate. TOE examinations were performed before and after the operation; 1,673 (88.5%) patients underwent cardiopulmonary bypass (CPB), and 218 (11.5%) patients had surgery without CPB, including 42 (2.2%) coronary revascularizations. In 923 patients (49%), TOE provided additional information that influenced the patient's therapy. In 968 patients (51%), TOE had only minor or no impact on clinical decision-making. In two patients (0.10%) the scheduled operation was not performed, and in another two patients the TOE examination led to major complications. Observer-dependent variables were: implications of TOE for intraoperative decision-making (P<0.0001), estimation of image quality (P < 0.0001), pre-operative left ventricular fractional area change (FAC) (P = 0.0026), difference between pre-operative FAC and post-operative FAC (P = 0.033), and requests for supervision (P < 0.0001). There was no significant difference in the case mix between observers. TOE had an important impact on intraoperative patient management. Inter-observer variability was significant for several variables but not for the frequency of additional surgical procedures.

Modification of surgical aortoatrial shunts for inaccessible bleeding in aortic surgery -- modification of the Cabrol-shunt technique.

Bleeding after complex ascending aortic, aortic root or transverse arch surgery which is inaccessible or difficult to control may present a major problem. Here, we describe a modified Cabrol-shunt technique using complete mediastinal coverage with decompression into the innominate vein where the classical technique is not suitable. The long-term fate of the classical aortoatrial and modified mediastinal to innominate shunts has been analyzed to assess their potential complications.

To compare general, epidural and local anaesthesia for endovascular aneurysm repair (EVAR).

OBJECTIVES: to compare general, epidural and local anaesthesia for endovascular aneurysm repair (EVAR). METHODS: retrospective analysis of 91 consecutive patients (age 43 to 89 years) who underwent EVAR under local (LA, 63 patients), epidural (EDA, 8 patients) and general (GA, 20 patients) anaesthesia. RESULTS: EVAR was successfully achieved in all patients without mortality or neurological, cardiac and respiratory complications. Vasopressive support as well as median fluid balance were significantly lessened in the LA group compared to GA group (p<0.0002). Stay in the Intensive Care Unit was necessary in 17 (27%), four (50%) and 14 (70%) patients, respectively, and median hospital stay was 3, 4.5, and 5.5 days, with a statistically significant difference between LA and GA group (p<0.0005). CONCLUSION: LA is a safe anaesthetic method for the endovascular repair of infrarenal abdominal aneurysm, offering several advantages: simplicity, stable haemodynamics, and reduced consumption of ICU and hospital beds.

Inhaled nitric oxide for pulmonary hemorrhage due to acute pulmonary vein trauma.

A 57-year-old man with a history of prosthetic aortic valve and supracoronary ascending aortic replacement presented with a 9.8 cm Sinuses of Valsalvae aneurysm ruptured into the left upper pulmonary vein leading to massive pulmonary hemorrhage due to acute rupture of small pulmonary veins. Prosthetic graft replacement of the aneurysm and reconstruction of the atrial roof and left upper pulmonary vein was performed. Inhaled nitric oxide reversed treatment-refractory hypoxemia following massive small pulmonary vein trauma.

Left ventricular pressure-area relations as assessed by transoesophageal echocardiographic automated border detection: comparison with conductance catheter technique in cardiac surgical patients.

The aim of this study was to validate measurements of intraoperative left ventricular (LV) area by transoesophageal echocardiography against simultaneous measurements of LV volume by conductance catheter (CC) in cardiac surgical patients with normal systolic LV function. Echo area was compared with CC volume during steady state and during acute changes of pre- and afterload by partial clamping of the inferior vena cava and the ascending aorta in eight patients scheduled for coronary artery bypass grafting. At steady state, Bland-Altman analysis of 32 recordings revealed a bias (SD) of 0.6% (2.5%) between echo area and CC volume, related to the initial values of end-diastolic area (100% area) and volume (100% volume), respectively. During loading interventions, bias between the two methods, as assessed by 112 measurement sequences, was 0.5% (3.7%) during aortic occlusion and -3.9% (4.4%) during cava occlusion at end-systole (P < 0.0001); at end-diastole, this bias was 1.3% (4%) during aortic occlusion and 0.2% (5.7%) during cava occlusion (P < 0.0001). Intraoperative area measurements with transoesophageal echocardiography in cardiac surgical patients with normal systolic LV function show good correlation with CC volume measurements under steady-state conditions. During acute unloading by vena cava occlusion, the resulting small end-systolic echo area measurements differ significantly more from CC volume measurements than during acute increase in afterload by aortic occlusion.

Inhaled nitric oxide versus intravenous vasodilators in severe pulmonary hypertension after cardiac surgery.

UNLABELLED: Inhaled nitric oxide (iNO) is superior to i.v. vasodilators for treatment of pulmonary hypertension (PH) after cardiac surgery, but iNO is a potentially toxic gas, and patient subsets who benefit from iNO are not yet clearly defined. We administered iNO 40 ppm, prostaglandin E1 (PGE1) 0.1 microg x kg(-1) min(-1), and nitroglycerin (NTG) 3 to 5 microg x kg(-1) min(-1), in a randomized crossover study to 14 adult patients with severe PH after cardiac surgery. iNO, PGE1, and NTG were of similar efficacy in reducing pulmonary vascular resistance (P = 0.003). iNO induced selective pulmonary vasodilation, while PGE1 and NTG had significant concomitant systemic vasodilatory effects. iNO led to an increase in cardiac index (CI) (P = 0.012), and PGE1 increased CI (P = 0.006) and right ventricular (RV) ejection fraction (P = 0.015), while NTG had no effect on CI and RV performance. After study completion, patients continued with PGE1 administration with favorable in-hospital outcome. We conclude that PH per se, even if severe, does not necessarily imply postoperative RV dysfunction, and selective pulmonary vasodilation with iNO may not be superior to PGE1 with regard to CI and RV performance. IMPLICATIONS: In a prospective, randomized crossover study of inhaled nitric oxide (iNO) versus IV vasodilators, performed in adult patients with severe pulmonary hypertension but preserved right ventricular function after cardiac surgery, iNO was not superior to IV prostaglandin E1 with regard to cardiac index and right ventricular performance. Considering the potential toxicity of iNO, better definition of patient subsets with a positive benefit/risk ratio is warranted.

Recent experience with the arterial switch operation in transposition of the great arteries.

OBJECTIVE: Review of our experience with the technically demanding arterial switch operation in transposition of the great arteries in children. METHODS: Twenty-seven children who underwent an arterial switch operation in our clinic were retrospectively reviewed. Except for one child (operated on at eight months), the operation was performed during the neonatal period. The underlying pathology was d-transposition of the great arteries in 25 children and a double outlet right ventricle of transposition type in 2. Five children had an associated ventricular septum defect and 1 aortic isthmus coarctation. The pattern of the coronary arteries was favourable in 18 children, difficult in 7 and dangerous in 3. The operation was performed in cardiopulmonary bypass for repair of the transposition and in a period of deep hypothermic circulatory arrest for repair of the intracardiac defects. RESULTS: One child died perioperatively and 1 postoperatively (operative mortality 7%) from myocardial ischaemia following unsuccessful transfer of a dangerous pattern of coronary arteries. Another child, a low-birth weight baby, died 80 days after the operation from respiratory failure. Postoperative morbidity occurred in 10 patients and medium-term morbidity in 6 patients who presented various degrees of stenosis of a pulmonary artery. During a median follow-up of 18 months no patient required reoperation. The children are asymptomatic and thriving satisfactorily. CONCLUSION: Because it restores the heart physiology, the arterial switch operation is considered the procedure of choice for correction of transposition of the great arteries. The operation involves acceptable mortality and morbidity. Transfer of difficult coronary artery patterns and development of stenosis on the pulmonary arteries remain problematic.

Transesophageal echocardiographic area and Doppler flow velocity measurements: comparison with hemodynamic changes in coronary artery bypass surgery.

OBJECTIVE: Changes in transesophageal echocardiography (TEE)-derived Doppler flow velocities through the mitral valve and pulmonary veins occur after cardiopulmonary bypass and are believed to reflect left ventricular (LV) diastolic functional impairment. The aim of this study was to determine the time-coincidence between these Doppler flow velocity parameters, LV two-dimensional (2D) short-axis area measurements, and hemodynamic parameters in patients after coronary artery bypass grafting. DESIGN: Prospective clinical study. SETTING: University hospital. PARTICIPANTS: Twenty patients with normal ejection fraction undergoing elective cardiac surgery. INTERVENTIONS: At multiple intervals during surgery and 6 hours postoperatively, mitral inflow velocity and pulmonary venous flow velocity were measured with pulsed Doppler TEE. LV short-axis area by echocardiography and cardiac output by thermodilution were simultaneously obtained. MEASUREMENTS AND MAIN RESULTS: Time-coincidence was found in the immediate postbypass period between a decreased E/A ratio from 1.16 (95% confidence interval, 1.0 to 1.31) to 0.64 (95% confidence interval, 0.47 to 0.81, p < 0.01), a decreased E-wave deceleration time, and a significantly increased heart rate (HR) and cardiac index. End-diastolic area (EDA) and stroke volume index (SVI) decreased after sternal closure. HR, E-wave deceleration time, and SVI remained altered until 6 hours postoperatively. No change was found in pulmonary venous flow velocity parameters and systolic LV function. CONCLUSION: In patients with normal systolic ventricular function and no inotropic support, Doppler flow velocity patterns alone did not sufficiently reflect hemodynamic changes, whereas 2D LV area, especially EDA measurements, provided useful information about hemodynamically significant LV filling impairment.

Continuous thermodilution cardiac output: clinical validation against a reference technique of known accuracy.

OBJECTIVE: To evaluate the accuracy and precision of continuous thermodilution (CCO) by using a validated bolus thermodilution (BCO) reference technique as criterion standard. DESIGN: Under circulatory steady state conditions, a CCO system (Vigilance, software versions 4.35 and 4.39) was validated with regard to CCO as well as iced and room temperature BCO. SETTING: Intensive care unit at a university hospital. PATIENTS: Method comparison was conducted in 56 cardiac surgical patients, 28 patients being allocated to one of the two software versions, and 14 within each group to either iced or room temperature BCO. MEASUREMENTS AND RESULTS: CCO readings were registered in duplicate before and after three to five bolus injections conducted with both the Vigilance and reference systems. Iced BCO showed excellent agreement between the Vigilance and reference systems, yielding SDs of bias of 0.41 and 0.37 l/min and linear correlation coefficients (r) of 0.97 and 0.96. With room temperature BCO, agreement was significantly less. CCO, irrespective of software version, showed higher SDs of bias (0.90 and 0.84 l/min) and lower r values (0.84 and 0.81) than iced BCO (p < 0.0001). CCO measurements with software version 4.39 yielded a similar SD of bias to that with room temperature BCO. CONCLUSION: Decreased precision of CCO as compared to iced BCO may, in clinical settings, be outweighed by the advantages of automated and continuous monitoring. Under research conditions, however, iced BCO remains the method of choice.

Complete thromboendarterectomy of the calcified ascending aorta and aortic arch.

BACKGROUND: Arteriosclerotic plaques of the ascending aorta and transverse arch increase the operative risk of cardiac operations and are strong predictors for late cerebrovascular events. METHODS: Twenty-two patients, mean age 68 +/- 6 years (range, 55 to 77 years), with grade IV + V plaques of the ascending aorta and transverse arch underwent coronary artery bypass grafting (n = 21) and aortic valve replacement (n = 8). Cerebrovascular emboli from unknown sources were found preoperatively in 8 patients (36%). All were in sinus rhythm. Complete thromboendarterectomy of the ascending aorta and transverse arch was performed during hypothermic circulatory arrest. After 21 +/- 12 months (range, 4 to 44 months), magnetic resonance imaging and transthoracic echocardiography of endarterectomized vessels was performed. RESULTS: There was one perioperative death (4.5%), one early (4.5%), and one late (4.7%) adverse neurologic event. Follow-up examinations revealed normal diameters of the endarterectomized aorta. CONCLUSIONS: For patients with grade IV + V plaques, thromboendarterectomy of the ascending aorta and transverse arch can be performed with an acceptable surgical risk and a low recurrence rate for cerebrovascular events. Dilatation of the endarterectomized aorta was not observed.

Emergency repair of incidentally diagnosed ascending aortic aneurysm immediately after caesarean section.

A 36-yr-old pregnant woman with a history of hypertension presented at term for elective Caesarean section because of breech position. At preoperative examination, a diastolic murmur was found and transoesophageal echocardiography (TOE) revealed a large, 8.1-cm diameter ascending aortic aneurysm with severe aortic regurgitation and moderate pericardial effusion. Surgical repair was not considered to be urgently required. The patient was delivered electively by Caesarean section under epidural anaesthesia using invasive arterial pressure monitoring. TOE performed 6 h post-partum showed progressing pericardial effusion, for which emergency replacement of the aortic valve and ascending aorta were indicated. The epidural catheter was removed 4 h before starting the cardiopulmonary bypass procedure. Arterial pressure was controlled by a titrated infusion of esmolol and clonidine. To improve uterine tone, the patient received an i.v. infusion of oxytocin throughout surgery. After implantation of an aortic composite graft and weaning from cardiopulmonary bypass, the patient was transferred to the intensive care unit. Awake and receptive to neurological evaluation, her trachea was extubated 4 h after surgery. Mother and baby made an uneventful recovery.