Fast detection of diffuse axonal damage in severe traumatic brain injury: comparison of gradient-recalled echo and turbo proton echo-planar spectroscopic imaging MRI sequences

BACKGROUND AND PURPOSE: Diffuse axonal injury (DAI) is a common type of primary neuronal injury in patients with severe traumatic brain injury (TBI), and is frequently accompanied by tissue tear hemorrhage. T2-weighted gradient-recalled echo (GRE) sequences are more sensitive than T2-weighted spin-echo images for detection of hemorrhage. The purpose of this study is to compare turbo Proton Echo Planar Spectroscopic Imaging (t-PEPSI), an extremely fast sequence, with GRE sequence in the detection of DAI. METHODS: Twenty-one patients (mean age 26.8 years) with severe TBI occurred at least 3 months earlier, underwent a brain MR Imaging study on a 1.5-T scanner. A qualitative evaluation of the t-PEPSI sequences was performed by identifying the optimal echo time and in-plane resolution. The number and size of DAI lesions, as well as the signal intensity contrast ratio (SI CR), were computed for each set of GRE and t-PEPSI images, and divided according to their anatomic location as lobar and/or deep brain. RESULTS: There was no significant difference between GRE and t-PEPSI sequences in the detection of the total number of DAI lesions (291 vs. 230, respectively). GRE sequence delineated a higher number of DAI in the temporal lobe compared to the t-PEPSI sequence (74 vs. 37, P < .004), while no differences were found for the other regions. The SI CR was significantly lower with the t-PEPSI than the GRE sequence (P < .00001). CONCLUSION: Owing to its very short scan time and high sensitivity to the hemorrhage foci, the t-PEPSI sequence may be used as an alternative to the GRE to assess brain DAI in severe TBI patients, especially if uncooperative and medically unstable.     

Signal verification of middle latency auditory evoked potentials by automated detection of the brainstem response

BACKGROUND: The midlatency components of auditory evoked potentials (AEPs) are gradually suppressed with increasing concentrations of anesthetics. Thus, they have been proposed as a monitor of anesthetic depth. However, undetected malfunction or disconnection of headphones and undetected hearing loss also result in suppressed midlatency AEPs that in turn may be misinterpreted as signs of deep anesthesia. As the brainstem component of the AEP is minimally influenced by anesthetics, its presence or absence can be used to verify that the recorded signal is a true AEP rather than an artifact. In this study, an online-capable procedure for detection of the brainstem component of the AEP was developed. METHODS: One hundred and ninety perioperatively recorded AEPs (binaural stimuli, 500 sweeps) were selected from a database with electroencephalographic and concomitant AEP stimulus information. Identical electroencephalogram regions were used to produce nonstimulus synchronized averaged signals (500 sweeps, "non-AEP"). The 190 AEPs and 190 "non-AEPs" were used to develop a detector of the brainstem component of AEPs. AEPs and "non-AEPs" were wavelet transformed (discrete wavelet decomposition, biorthogonal 2.2 mother-wavelet), and the coefficient with the best separation of the two classes of signals was selected. Receiver operating characteristic curve analysis was performed to determine the optimum threshold value for this coefficient. RESULTS: The third coefficient of the third level was selected. In AEP signals, retransform of this coefficient produces a peak that resembles peak V of the brainstem response. The developed detector of the brainstem component of AEP had a sensitivity of 97.90% and a specificity of 99.48%. CONCLUSIONS: This detector of the AEP brainstem component can be used to verify that the signal reflects the response to an auditory stimulus. An alternative approach, used in the Danmeter AEP monitor, is based on the signal-to-noise ratio of the midlatency components of the AEP. Because the midlatency components of AEP are suppressed by anesthesia, a false alarm "low AEP/no AEP" is generated during deep anesthesia. This, in turn, may suggest disconnection of headphones or technical problems whenever anesthesia is deep. This disadvantage has been overcome by our detector, which is based on the identification of the brainstem component of AEP.     

Heller myotomy for failed pneumatic dilation in achalasia: how effective is it?

OBJECTIVES: This long-term prospective study describes the effect of myotomy in patients who fail to respond to repeated pneumatic dilations and compares their clinical course with that of patients responding to dilation therapy. METHODS: Nineteen consecutive patients who had never reached a clinical remission after repeated pneumatic dilation underwent myotomy. Their clinical course was compared with that of patients who had reached a clinical remission after a single (n = 34) or multiple (n = 14) pneumatic dilation(s). Symptoms were graded with a previously described symptom score ranging from 0 to 12. Remission was defined as a score of 3 or less persisting for at least 6 months. Duration of remission was summarized using Kaplan Meier survival curves. Association between baseline factors and the need for surgery was evaluated using logistic regression. RESULTS: Complete follow-up was obtained for 98.5% of the patients. The median duration of follow-up was similar in patients treated by myotomy (10.0 years), in patients reaching a clinical remission after a single dilation (10.6 years), but differed in patients undergoing repeated dilations (6.9 years). The 10-year remission rate was 77% (95% CI 53-100%) in patients undergoing myotomy, 72% (95% CI: 56-87%) in patients "successfully" treated with a single pneumatic dilation and 45% (95% CI: 16-73%) in patients undergoing several dilations. Among all baseline factors investigated, young age was associated with an increased need of surgery. CONCLUSIONS: Myotomy is an effective treatment modality in patients with achalasia who have failed to respond to pneumatic dilation. Young patients may benefit from primary surgical therapy.     

Predictors of mortality at initiation of peritoneal dialysis in children after cardiac surgery

BACKGROUND: The development of renal dysfunction in the postoperative course of cardiac surgery is still associated with high mortality in pediatric patients. In particular for small infants peritoneal dialysis offers a secure and useful treatment option. The aim of the present study was to investigate if routinely used laboratory and clinical variables could help predict mortality at initiation of peritoneal dialysis. METHODS: We performed a retrospective chart analysis of pediatric intensive care unit patients with renal dysfunction who were treated with peritoneal dialysis after cardiac surgery between 1993 and 2001 and analyzed variables obtained 3 hours or less before starting peritoneal dialysis. RESULTS: Results are documented as means and standard errors. A total of 1141 children underwent a cardiac operation on cardiopulmonary bypass. Sixty-two children (5.4%) were treated with peritoneal dialysis. Mortality was 40.3% (37 survivors, 25 nonsurvivors). The pH in survivors was 7.35 (0.01); in nonsurvivors it was 7.23 (0.03; p = 0.0037). Base excess in survivors was -1.37 mmol/L (0.61); in nonsurvivors it was -7.17 mmol/L (1.49; p = 0.0026). Lactate in survivors was 4.5 mmol/L (0.60); in nonsurvivors it was 10.5 mmol/L (1.78; p = 0.0089). Positive inspiratory pressure in survivors was 24.6 cm H(2)O (0.78); in nonsurvivors it was 28.9 cm H(2)O (1.08; p = 0.0274). Tidal volume per kilogram bodyweight in survivors was 11.0 mL/kg (0.48); in nonsurvivors it was 8.7 mL/kg (0.50; p = 0.0493). CONCLUSIONS: We conclude from our data that the consideration of pH, base excess, lactate, positive inspiratory pressure, and tidal volume per kilogram bodyweight help predict mortality at initiation of peritoneal dialysis. We were able to observe significant differences between survivors and nonsurvivors using these variables.     

Risk factors assessment of the difficult airway: an italian survey of 1956 patients

Over the last decade, there has been a heightened awareness and an increase in the amount of literature being published on recognition and prediction of the difficult airway. During the preoperative evaluation of the airway, a thorough history and physical specifically related to the airway should be performed. Various measurements of anatomic features and noninvasive clinical tests can be performed to enhance this assessment. In this study we correlated the Mallampati modified score and several other indexes with the laryngoscopic view to identify anatomical and clinical risk factors related to the difficult airway. We prospectively collected data on 1956 consecutive patients scheduled to receive general anesthesia requiring endotracheal intubation for elective surgery. The Mallampati classification versus the Cormack-Lehane (C-L) linear correlation index was 0.904. A Mallampati Class 3 correlated with a C-L Grade 2 (0.94), whereas a Mallampati Class 4 correlated with a C-L Grade 3 (0.85) and a C-L Grade 4 (0.80). Operator evaluation, performed by a simplified tracheal intubation difficulty scale, showed a linear correlation of 0.96 compared with the C-L groups. Although there is a correlation between oropharyngeal volume and difficult intubation, the Mallampati score by itself is insufficient for predicting difficult endotracheal intubation.     

Impact of bispectral index monitoring on stress response and propofol consumption in patients undergoing coronary artery bypass surgery

BACKGROUND: Bispectral Index (BIS)-titrated administration allows a reduction of propofol infusion rates in patients undergoing surgery. Resulting differences in anesthetic depth might affect the stress response to surgery involving neural circuitry not reflected in the electroencephalogram. METHODS: Forty patients scheduled to undergo elective coronary artery bypass grafting receiving a background infusion of remifentanil (0.3 microg . kg . min) were anesthetized with intravenous propofol delivered by target-controlled infusion according to the Marsh pharmacokinetic model under BIS monitoring. In a randomized, prospective design, 20 patients received propofol at a target concentration of 3 microg/ml, whereas in 20 patients propofol was titrated to maintain a BIS value of 40-50. Plasma concentrations of propofol (by means of gas chromatography-mass spectrometry), epinephrine, norepinephrine (by means of high-pressure liquid chromatography), cortisol (by means of radioimmunoassay), and interleukins 6 and 10 (by means of enzyme-linked immunosorbent assay) were measured repeatedly throughout surgery. RESULTS: BIS monitoring allowed a 30% reduction of propofol infusion rates and a similar decrease in plasma propofol concentrations in the BIS group without affecting the stress response to surgery for the group mean. None of the patients reported awareness during a standardized interview. Interestingly, propofol-remifentanil anesthesia blunted the release of epinephrine and cortisol to bypass surgery completely even when the propofol infusion rate was reduced according to BIS values. CONCLUSIONS: Total intravenous anesthesia using propofol-remifentanil effectively attenuates the neurohumoral stress response to coronary bypass surgery involving cardiopulmonary bypass. Titration of propofol using BIS allows for significant reduction of propofol consumption, with only minor effects on stress response under these conditions.     

Testing of extracorporeal membrane oxygenation circuit related hemolysis using long-term stored packed red cells and fresh frozen plasma

BACKGROUND: The resistance of blood used in these studies to hemolysis differs markedly from that used in neonatal extracorporeal circulation under clinical circumstances. In this study, the possibility of using expired packed red cells to determine hemolysis caused by mechanical and/or environmental factors was investigated. METHODS: Packed red blood cells stored for 42 days were mixed with fresh frozen plasma and the resultant mixture was divided into three groups, two study groups and a control. For the study groups, two different centrifugal pump heads (Medtronic BP 50 and Jostra RF 32) were used in an extracorporeal membrane oxygenation (ECMO) circuit. Free hemoglobin, lactate dehydrogenase, lactic acid, pH, potassium, and glucose were investigated at various time intervals. RESULTS: Hemolysis did not differ between the groups. Free hemoglobin increased in all groups after 12 h. Lactic acid increased linearly in all groups up to 12 h. Glucose and pH decreased steadily in all groups. Hemolysis created during mock ECMO did not differ between the circuits using the two different pump heads noted. CONCLUSION: Human donor blood stored up to its expiration date is a feasible medium for mock circulation tests of up to 12 h duration under the circumstances described.     

The role of complete surgical resection in stage IV neuroblastoma

The purpose of this study was to examine the outcome of attempted radical surgical resection in patients with stage IV neuroblastoma. Between 1989 and 2003, 20 (median age 2.4 years, range 0.5–8.7 years) children with stage IV neuroblastoma were treated at the Department of Pediatrics. Surgery was performed in 7 consecutive children (6 male and 1 female) between July 1997 and February 2002 at the Department of Urology in Bonn. Mean age at diagnosis was 57 months (21–104 months). Mean age at the time of surgery was 54 months (8–390 months). Follow-up was available for all patients (100%) and mean follow-up after the operation was 32.5 months (4–56 months). Primary localization of the tumor was retroperitoneal in all cases; 4 out of 7 patients (57%) also had additional adrenal, 3 out of 7 (42%) paraganglion and 1 out of 7 (14%) thoracic primaries. Bone marrow and lymph node metastases were found in all patients (100%). Surgery led to complete tumor resection in 6 out of 7 patients (85%). Surgical approach was abdominal (chevron incision) in 6 out of 7 (85%) of the patients, in one patient the approach was thoraco-abdominal. After induction chemotherapy and delayed surgery, 6 out of 7 (86%) patients showed a complete remission (CR) and the mean CR lasted for about 27.7 months (range 3.1–55.4 months). At the last time of follow-up 5 out of 7 (71%) patients were alive, 2 had died due to recurrent disease. Mean time to recurrent disease was 24 and 51 months, respectively. Mean overall survival time since diagnosis was 38.3 months (11–64 months) and mean event-free survival was 34.5 months (11–60.3 months). The final outcome, overall survival and event-free survival time was influenced by metastatic or local relapse. Tumor resection is beneficial but the value of surgery can only be judged when we are able to control metastatic disease in stage IV neuroblastoma. The final outcome may rely on the extent of complete surgical resection, but is also related to treatment of metastases. A longer follow-up period is indicated to detect long term outcome.