Daniel Schmidlin

Minimal Changes of Serum Creatinine Predict Prognosis in Patients after Cardiothoracic Surgery: A Prospective Cohort Study

Acute renal failure increases risk of death after cardiac surgery. However, it is not known whether more subtle changes in renal function might have an impact on outcome. Thus, the association between small serum creatinine changes after surgery and mortality, independent of other established perioperative risk indicators, was analyzed. In a prospective cohort study in 4118 patients who underwent cardiac and thoracic aortic surgery, the effect of changes in serum creatinine within 48 h postoperatively on 30-d mortality was analyzed. Cox regression was used to correct for various established demographic preoperative risk indicators, intraoperative parameters, and postoperative complications. In the 2441 patients in whom serum creatinine decreased, early mortality was 2.6% in contrast to 8.9% in patients with increased postoperative serum creatinine values. Patients with large decreases (DeltaCrea <-0.3 mg/dl) showed a progressively increasing 30-d mortality (16 of 199 [8%]). Mortality was lowest (47 of 2195 [2.1%]) in patients in whom serum creatinine decreased to a maximum of -0.3 mg/dl; mortality increased to 6% in patients in whom serum creatinine remained unchanged or increased up to 0.5 mg/dl. Mortality (65 of 200 [32.5%]) was highest in patients in whom creatinine increased > or =0.5 mg/dl. For all groups, increases in mortality remained significant in multivariate analyses, including postoperative renal replacement therapy. After cardiac and thoracic aortic surgery, 30-d mortality was lowest in patients with a slight postoperative decrease in serum creatinine. Any even minimal increase or profound decrease of serum creatinine was associated with a substantial decrease in survival.

Impact of minimal increases in serum creatinine on outcome in patients after cardiothoracic surgery: do we have to revise current definitions of acute renal failure?

Objective:Traditional cutoff values of serum creatinine considered to define postoperative acute renal failure have been challenged recently. In a previous investigation we demonstrated that minimal changes in serum creatinine concentration were associated with a substantial decrease in survival after cardiac surgery. In this investigation, we assessed the impact of minimal absolute increases in serum creatinine in a second institution, and we analyzed whether relative changes, as in the RIFLE classification and, partially, in Acute Kidney Injury Network (AKIN) classification, confer a different prognostic potential. Design:Prospective analysis. Setting:University hospital. Patients:All consecutive patients undergoing cardiac surgery in the University Hospital of Zurich (Center USZ) over a 46-month period. Interventions:Patients were prospectively documented. We analyzed maximal changes in serum creatinine in the first 48 hrs postoperatively (&Dgr;Crea) regarding death within 30 days. Results were compared with those of the University Hospital Vienna (Center AKH). Moreover, the prognostic potential of &Dgr;Crea within 48 hrs vs. serum creatinine elements according to RIFLE and AKIN classifications was assessed. Measurements and Main Results:A total of 3,123 patients were evaluated from USZ. The majority of patients had decreased postoperative serum creatinine values (negative &Dgr;Crea) and the lowest mortality (1.8%). Minimal increases, [0, 0.5) mg·dL−1, were associated with a more than doubled mortality in both centers (5%/6%). Mortality, according to RIFLE and AKIN classifications for both populations combined, was as follows: 7,023 (3.6%), 160 (29%), 43 (19%), and 15 (33%) for RIFLE Normal, Risk, Injury, and Failure; 6,644 (2.8), 463 (16.4), 3 (66.7), and 131 (1.8) for AKIN stage 0, 1, 2, and 3. Conclusions:Measuring repeat serum creatinine concentrations within 48 hrs and determining &Dgr;Crea were the most effective discrimination method to find patients at risk for adverse postoperative outcome after cardiac surgery, better than application of this sole criterion to the RIFLE (least discriminatory) or the AKIN classification.

Early postoperative arrhythmias after cardiac operation in children

BACKGROUND Arrhythmias are a recognized complication of cardiac operations. However, little is known about the incidence, treatment, and risk factors for early postoperative arrhythmias in children after cardiac operations. METHODS Diagnosis and treatment of early postoperative arrhythmias were prospectively analyzed in an intensive care unit in 100 consecutive children with a median age of 17 months (range, 1 day to 191 months) who had undergone cardiac operation. Patients were grouped in three different categories of surgical complexity. RESULTS During a median postoperative time of 1 day (range, 0 to 15 days), 64 critical arrhythmias occurred in 48 patients. Arrhythmias consisted of sinus bradycardia in 30, atrioventricular block II to III in 7, supraventricular tachyarrhythmias in 14, and premature complexes in 13 instances. Treatment of 52 arrhythmias was successful and included pacing in 41, intravenous amiodarone in 8, body cooling in 5, overdrive pacing in 3, and electrolyte correction in 2 cases, with more than one treatment modality in 8 cases. Risk factors for arrhythmias were lower body weight (p < 0.05), longer cardiopulmonary bypass duration (p < 0.05), and a category of higher surgical complexity (p < 0.001). CONCLUSIONS Early postoperative arrhythmias occur frequently after cardiac operations in children. Sinus bradycardia, atrioventricular block II to III, and supraventricular tachyarrhythmias are the most frequent arrhythmias, which, however, can be treated effectively by means of temporary pacing, cooling, and antiarrhythmic drug therapy. Lower body weight, longer cardiopulmonary bypass duration, and a higher surgical complexity are risk factors for early postoperative arrhythmias.

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.

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.

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.

Intrathecal sufentanil-morphine shortens the duration of intubation and improves analgesia in fast-track cardiac surgery.

PurposeTo compare the effect of combined intrathecal morphine and sufentanil with low-doseiv sufentanil during propofol anesthesia for fast-track cardiac surgery.MethodsTwenty-four consecutive patients with normal cardiopulmonary function who were scheduled for elective cardiac surgery were randomized to receive either a continuousiv infusion of sufentanil 0.9 to 1.8μg· kg−1· min−1 (13 patients), or a single lumbar intrathecal dose of sufentanil 50 μg and morphine 500 μg (11 patients). We prospectively studied perioperative analgesia, time to extubation and early postoperative maximal inspiratory capacity in the two groups. In the intensive care unit, the medical and nursing staff were blinded to the analgesic technique.ResultsIntrathecal sufentanil morphine allowed a shorter duration of intubation (104 ± 56.5 minvs 213 ± 104 min;P = 0.01), reduced the need for postoperative analgesia with nicomorphine (equipotentto morphine) (0.7 ± 0.4 mg· hr−1vs 1.2 ± 0.4 mg· hr−1;P = 0.008) and improved postoperative maximal inspiratory capacity (53.4 ± 16.1vs 38.4 ± 12.5% of the norm;P = 0.05). Conclusion: In low-risk patients undergoing coronary artery bypass graft or valve surgery, combined intrathecal sufentanil and morphine with a target-controlled infusion of propofol satisfies the goals of fast-track cardiac surgery.RésuméButComparaison de l’effet de l’administration intrathécale combinée de morphine et de sufentanil avec l’administration iv de sufentanil lors d’une anesthésie à base de propofol pour la chirurgie cardiaque “fast-track”.MéthodeVingt-quatre patients consécutifs ayant une fonction cardiopulmonaire dans les limites de la normale ont été admis en vue d’une intervention cardiaque programmée et ont été randomisés en deux groupes distincts: l’un recevant une perfusion iv continue de 0,9 à 1,8 μg· kg−1· min−1 de sufentanil (13 patients) et l’autre une dose unique intrathécale de 50 μg de sufentanil et 500 μg de morphine (11 patients). Nous avons étudié prospectivement l’analgésie périopératoire, le délai d’extubation et la capacité inspiratoire maximale postopératoire dans ces deux groupes de patients. Aux soins intensifs, le personnel soignant médical et paramédical ignoraient la technique analgésique utilisée.RésultatsL’administration intrathécale de sufentanil et de morphine a permis une extubation plus rapide (104 ± 56,5 min vs 213 ± 104 min; P = 0,01), une réduction des besoins analgésiques en nicomorphine (puissance équivalente à la morphine) (0,7 ± 0,4 mg· h−1 vs 1,2 ± 0,4 mg· h−1; P = 0,008) et une amélioration de la capacité inspiratoire maximale postopératoire (53,4 ± 16,1 vs 38,4 ± 12,5 % de la norme; P = 0,05).ConclusionChez les patients à bas risque opératoire programmés pour des pontages aortocoronariens ou un remplacement valvulaire simple, l’administration intrathécale de morphine et sufentanil en dose unique satisfait les critères de chirurgie cardiaque “fast-track”.

Ibutilide versus amiodarone in atrial fibrillation: a double-blinded, randomized study.

ObjectiveIbutilide, a class III antiarrhythmic drug, has been shown to convert atrial fibrillation to sinus rhythm more rapidly than procainamide or sotalol. Our objective was to compare the efficacy and safety of ibutilide and amiodarone in patients after cardiac surgery. DesignProspective, randomized, double-blinded study. SettingIntensive care unit of a university hospital. PatientsForty adults with an onset of atrial fibrillation within 3 hrs after admission. InterventionsBefore the administration of antiarrhythmic drugs, a 24-hr Holter electrocardiograph was attached. Patients in the ibutilide group received ibutilide 0.008 mg/kg body weight over 10 mins; treatment was repeated if atrial fibrillation or flutter persisted. If sinus rhythm was not achieved within 4 hrs, amiodarone 5 mg/kg was administered over 30 mins, followed by amiodarone 15 mg/kg over 24 hrs. Patients in the amiodarone group received amiodarone 5 mg/kg over 30 mins, followed by amiodarone 15 mg/kg over 24 hrs if atrial fibrillation or flutter continued. Measurements and Main ResultsWithin the first 4 hrs, atrial fibrillation was converted in nine of 20 patients (45%) in group ibutilide and in ten of 20 patients (50%) in group amiodarone (not significant). Mean time for conversion overall was 385 mins in group ibutilide and 495 mins in group amiodarone (not significant). In group amiodarone, the protocol was discontinued in two patients because of severe arterial hypotension. Atrial fibrillation recurred in 11 of 20 patients (55%) in group ibutilide and in seven of 20 patients (35%) in group amiodarone (not significant). Ventricular arrhythmia did not occur during the first 24 hrs of the protocol. ConclusionsIbutilide has no significant advantage over amiodarone for the conversion of atrial fibrillation to sinus rhythm in either time to conversion or conversion overall, but severe hypotension was not seen with ibutilide.

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.

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.