Manfred D. Seeberger

Principles and Practice of Thromboelastography in Clinical Coagulation Management and Transfusion Practice

In the recent years, thromboelastography has become a popular monitoring device for hemostasis and transfusion management in major surgery, trauma, and hemophilia. Thromboelastography is performed in whole blood and assesses the viscoelastic property of clot formation under low shear condition. Thromboelastography can be performed with a variety of activator and inhibitors at different concentrations representing the most important factors for different intervals and clot formation variables reported in multiple studies and algorithms. Furthermore, fibrinogen levels and platelet counts have a major influence on thromboelastographic variables. In addition, differences in patient populations, devices, and preanalytical conditions contribute to some conflicting findings in different studies.

Rivastigmine for the prevention of postoperative delirium in elderly patients undergoing elective cardiac surgery : A randomized controlled trial

Objective:Cardiac surgery is frequently followed by postoperative delirium, which is associated with increased 1-year mortality, late cognitive deficits, and higher costs. Currently, there are no recommendations for pharmacologic prevention of postoperative delirium. Impaired cholinergic transmission is believed to play an important role in the development of delirium. We tested the hypothesis that prophylactic short-term administration of oral rivastigmine, a cholinesterase inhibitor, reduces the incidence of delirium in elderly patients during the first 6 days after elective cardiac surgery. Design:Double-blind, randomized, placebo-controlled trial. Setting:One Swiss University Hospital. Patients:One hundred twenty patients aged 65 or older undergoing elective cardiac surgery with cardiopulmonary bypass. Intervention:Patients were randomly assigned to receive either placebo or 3 doses of 1.5 mg of oral rivastigmine per day starting the evening before surgery and continuing until the evening of the sixth postoperative day. Measurements and Main Results:The primary predefined outcome was delirium diagnosed with the Confusion Assessment Method within 6 days postoperatively. Secondary outcome measures were the results of daily Mini-Mental State Examinations and clock drawing tests, and the use of a rescue treatment consisting of haloperidol and/or lorazepam in patients with delirium. Delirium developed in 17 of 57 (30%) and 18 of 56 (32%) patients in the placebo and rivastigmine groups, respectively (p = 0.8). There was no treatment effect on the time course of Mini-Mental State Examinations and clock drawing tests (p = 0.4 and p = 0.8, respectively). There was no significant difference in the number of patients receiving haloperidol (18 of 57 and 17 of 56, p = 0.9) or lorazepam (38 of 57 and 35 of 56, p = 0.6) in the placebo and rivastigmine groups, respectively. Conclusion:This negative or, because of methodologic issues, possibly failed trial does not support short-term prophylactic administration of oral rivastigmine to prevent postoperative delirium in elderly patients undergoing elective cardiac surgery with cardiopulmonary bypass.

Epidural abscess complicating epidural anesthesia and analgesia: An analysis of the literature

Background: Epidural abscess is a serious complication of epidural block. Because of its low incidence, the risk factors and the symptoms and cause of epidural abscess related to epidural anesthesia and analgesia are not well known by anesthesiologists.

Modifiable and Nonmodifiable Risk Factors for Postoperative Delirium After Cardiac Surgery With Cardiopulmonary Bypass

OBJECTIVES Postoperative delirium after cardiac surgery is associated with increased morbidity and mortality as well as prolonged stay in both the intensive care unit and the hospital. The authors sought to identify modifiable risk factors associated with the development of postoperative delirium in elderly patients after elective cardiac surgery in order to be able to design follow-up studies aimed at the prevention of delirium by optimizing perioperative management. DESIGN A post hoc analysis of data from patients enrolled in a randomized controlled trial was performed. SETTING A single university hospital. PARTICIPANTS One hundred thirteen patients aged 65 or older undergoing elective cardiac surgery with cardiopulmonary bypass. INTERVENTIONS None. MEASUREMENTS AND MAINS RESULTS: Screening for delirium was performed using the Confusion Assessment Method (CAM) on the first 6 postoperative days. A multivariable logistic regression model was developed to identify significant risk factors and to control for confounders. Delirium developed in 35 of 113 patients (30%). The multivariable model showed the maximum value of C-reactive protein measured postoperatively, the dose of fentanyl per kilogram of body weight administered intraoperatively, and the duration of mechanical ventilation to be independently associated with delirium. CONCLUSIONS In this post hoc analysis, larger doses of fentanyl administered intraoperatively and longer duration of mechanical ventilation were associated with postoperative delirium in the elderly after cardiac surgery. Prospective randomized trials should be performed to test the hypotheses that a reduced dose of fentanyl administered intraoperatively, the use of a different opioid, or weaning protocols aimed at early extubation prevent delirium in these patients.

Randomized Comparison of Sevoflurane Versus Propofol to Reduce Perioperative Myocardial Ischemia in Patients Undergoing Noncardiac Surgery

Background— Volatile anesthetics provide myocardial preconditioning in coronary surgery patients. We hypothesized that sevoflurane compared with propofol reduces the incidence of myocardial ischemia in patients undergoing major noncardiac surgery. Methods and Results— We enrolled 385 patients at cardiovascular risk in 3 centers. Patients were randomized to maintenance of anesthesia with sevoflurane or propofol. We recorded continuous ECG for 48 hours perioperatively, measured troponin T and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) on postoperative days 1 and 2, and evaluated postoperative delirium by the Confusion Assessment Method. At 6 and 12 months, we contacted patients by telephone to assess major adverse cardiac events. The primary end point was a composite of myocardial ischemia detected by continuous ECG and/or troponin elevation. Additional end points were postoperative NT-proBNP concentrations, major adverse cardiac events, and delirium. Patients and outcome assessors were blinded. We tested dichotomous end points by &khgr;2 test and NT-proBNP by Mann–Whitney test on an intention-to-treat basis. Myocardial ischemia occurred in 75 patients (40.8%) in the sevoflurane and 81 (40.3%) in the propofol group (relative risk, 1.01; 95% confidence interval, 0.78–1.30). NT-proBNP release did not differ across allocation on postoperative day 1 or 2. Within 12 months, 14 patients (7.6%) suffered a major adverse cardiac event after sevoflurane and 17 (8.5%) after propofol (relative risk, 0.90; 95% confidence interval, 0.44–1.83). The incidence of delirium did not differ (11.4% versus 14.4%; P=0.379). Conclusions— Compared with propofol, sevoflurane did not reduce the incidence of myocardial ischemia in high-risk patients undergoing major noncardiac surgery. The sevoflurane and propofol groups did not differ in postoperative NT-proBNP release, major adverse cardiac events at 1 year, or delirium. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00286585.

Repeated dural punctures increase the incidence of postdural puncture headache.

Previous studies have failed to find a significant correlation between the number of dural punctures and the incidence of postdural puncture headache (PDPH), questioning the hypothesis that leakage of cerebrospinal fluid (CSF) through the dural tear is the cause of PDPH.We hypothesized that insufficient statistical power of these studies was the cause for this unexpected finding, and reexamined whether repeated dural punctures increase the incidence of PDPH by analyzing prospectively collected data on 8034 spinal anesthetics. Uneventful spinal anesthetics, including a single subarachnoid injection of local anesthetics, occurred in 7865 (97.9%) cases, whereas failed spinal anesthetics requiring repeated dural puncture for a second subarachnoid injection of local anesthetics occurred in 165 (2.1%) cases. The two groups were similar with regard to age, sex, and ASA physical status. We found that repeated dural punctures significantly increased the incidence of PDPH. We conclude that increased risk of PDPH is a disadvantage of performing a second subarachnoid injection of local anesthetics after a failed spinal anesthetic. Moreover, this result suggests that leakage of CSF through the dural tear is the most plausible cause of PDPH. (Anesth Analg 1996;82:302-5)

Acute Hypovolemia May Cause Segmental Wall Motion Abnormalities in the Absence of Myocardial Ischemia

New segmental wall motion abnormalities (SWMA) detected by echocardiography are considered sensitive and specific markers of myocardial ischemia.However, we have observed new SWMA during pacing-induced reductions in left ventricular filling, which resolved immediately with cessation of the atrial pacing and simultaneous restoration of filling. Therefore, we designed this study to determine whether acute reduction in filling can induce new SWMA in the absence of ischemia. Institution of cardiopulmonary bypass was used as a clinical model of acute reduction in filling, and a beat-by-beat analysis of left ventricular contraction, filling, blood pressures, and electrocardiogram was performed when the drainage of blood to the cardiopulmonary bypass machine rapidly emptied the heart. Acute reduction in filling induced new SWMA in 4 of 38 study patients. All 4 patients had preexisting abnormalities of left ventricular contraction, but translocation of these preexisting SWMA did not explain the new SWMA, nor did myocardial ischemia. We conclude that acute reduction in left ventricular filling can cause new SWMA in the absence of ischemia. This finding limits the usefulness of new SWMA as a marker of ischemia in the presence of acute reduction in filling, such as that secondary to severe hypovolemia. Implications: This study documented that acute reduction in cardiac filling can be associated with new systolic wall motion abnormalities detected by transesophageal echocardiography in the absence of documented myocardial ischemia. These findings indicate that segmental wall motion may not be a valid marker for ischemia in the setting of acute hypovolemia. (Anesth Analg 1997;85:1252-7)

Extradural abscess complicating lumbar extradural anaesthesia and analgesia in an obstetric patient.

A 33‐year‐old nulliparous woman with severe pre‐eclampsia was treated with extradural analgesia to control blood pressure and relieve pain during delivery. Nine hours after extradural catheter insertion a Caesarean section was performed due to uterine inertia. The extradural catheter was kept in place for 88 hours. Ten days following the extradural block she developed an extradural abscess and had to undergo a laminectomy. In a retrospective and, in part, prospective analysis on more than 13,000 extradural blocks, we studied the incidence of this dreaded complication and reviewed the literature on clinical findings, diagnosis and treatment.

The accuracy of non-invasive carbon dioxide monitoring: A clinical evaluation of two transcutaneous systems

We determined the accuracy of two transcutaneous carbon dioxide monitoring systems (SenTec Digital Monitor with V‐Sign Sensor and TOSCA 500 with TOSCA Sensor 92) for the measurement of single values and trends in the arterial partial pressure of carbon dioxide in 122 adult patients during major surgery and in 50 adult patients in the intensive care unit. One or several paired measurements were performed in each patient. The first measurement was used to determine the accuracy of a single value of transcutaneous carbon dioxide; the difference between the first and the last measurements was used to analyse the accuracy and to track trends. We defined a 95% limit of agreement of ≤1 kPa as being clinically useful. There was insufficient agreement between transcutaneous carbon dioxide partial pressure values derived from the two systems and arterial carbon dioxide values for both single values and trends as defined by our suggested limit of agreement. We conclude that these systems cannot replace conventional blood gas analysis in the clinical setting studied.

The prognostic value of troponin release after adult cardiac surgery — a meta-analysis

To assess the accuracy of increased troponin (Tn) concentrations for the prediction of mid-term (> or = 12 months) mortality after coronary artery bypass graft (CABG) and valve surgery, we performed a systematic review identifying all studies reporting on the association between postoperative troponin release and mortality after cardiac surgery. Studies were identified through 30 April 2008 by electronic searches of the MEDLINE, EMBASE and BIOSIS databases. Two reviewers independently selected studies, assessed methodological quality and extracted the data. We primarily considered mid-term (> or = 12 months) and secondarily short-term (< or = 30 days) all-cause mortality. A bivariate random-effects model was used to study determinants and to pool measures of prognostic accuracy of Tn. Seventeen studies fulfilled the inclusion criteria with a total of 237 mid-term deaths in 5189 patients and 296 short-term deaths in 9703 patients. The diagnostic odds ratio of increased Tn concentrations was 5.46 (95% confidence interval (CI) 2.0-14.6) for mid-term mortality and 6.57 (95% CI 4.3-10.1) for short-term mortality after adult cardiac surgery. Alternatively expressed, for troponin elevation, the sensitivity was 0.45 (0.26-0.67) and the specificity 0.87 (0.73-0.90) to predict mid-term mortality. The sensitivity was 0.59 (0.48-0.69) and the specificity 0.82 (0.72-0.89) for short-term mortality. Between-study variability was high. In conclusion, this meta-analysis provides evidence for an association between postoperative Tn release with mid- and short-term all-cause mortality after adult cardiac surgery. However, differences in populations, timing of Tn testing, Tn subunit and Tn assays make definitive conclusions about effect size and cut-off values difficult.