Costs of postoperative cerebrospinal fluid leakage: 1-year, retrospective analysis of 412 consecutive nontrauma cases

BACKGROUND: Cerebrospinal fluid (CSF) leaks are widely recognized as commonly occurring postoperative complications of neurosurgical procedures. We will focus on the direct costs associated with CSF leaks in a single center across multiple neurosurgical procedures, based on a retrospective analysis. We will also compare the costs of using a synthetic agent to prevent such leaks with these costs from a more recent study. METHODS: The single-center retrospective study was carried out at the Neurosurgical Center Nijmegen (University Medical Center St Radboud and Canisius Wilhelmina Hospital, Nijmegen, Netherlands) from January 01, 1999, until December 31, 1999. Four hundred twelve consecutive, nontrauma, elective procedures were examined. RESULTS: By applying strict criteria for CSF leakage (including those self-limiting subcutaneous minor CSF collection), we found an overall leak rate of 10.7% with a lower number for supratentorial and transsphenoidal procedures and much higher numbers for infratentorial procedures and extensive skull base procedures (6 [12.8%] of 47 and 18 [34.6%] of 52, respectively). The CSF leak in these 44 patients was associated with high additional costs which accounted for 21.7% of the total costs of all 412 procedures or on average 1508 per patient and procedure. If DuraSeal (Confluent Surgical, Inc, Waltham, MA) were to be used prophylactically for every procedure, and assuming a 4% leak rate postprocedure (which was achieved in a more recent study of 46 patients using DuraSeal), there would be a saving of 550 for every procedure (reduction in additional costs of CSF leak minus the cost of the sealant), or a total saving of 226600 in the series of 412 patients. CONCLUSION: Our analysis establishes that CSF leaks occur with high frequency and incur significant costs across all types of surgical procedures. A direct correlation of this complication (and ensuring costs) is observed with more extensive procedures, and reduction of these significant costs can be achieved by using augmentation of the dural closure with DuraSeal.     

Comparison of standard and artificial neural network estimators of hemodialysis adequacy

The National Kidney Foundation and the European Renal Association recommend routine measurement of hemodialysis (HD) dose and have set standards for adequacy of treatment. We compare the results of five methods for HD dose estimation, classifying each result as adequate or inadequate on the basis of equilibrated (eq) Urea Reduction Ratio (URR(eq)) > or = 65% or Kt/V(eq) > or = 1.2, to assess the accuracy of each method as a diagnostic tool. Data from 113 patients from two different dialysis units were analyzed. Equilibrated postdialysis blood urea was measured 60 min after each hemodialysis session to calculate URR(eq) and Kt/V(eq), considered as gold standard indexes (GSI). URR and Kt/V were estimated by using the Smye formula, an artificial neural network (ANN), modified URR, the second generation Kt/V Daugirdas formula, and standard indexes based on postdialysis urea, then compared to the GSI. For URR, best estimator was ANN (error rate: ER% = 12.70), followed by modified URR (ER% = 17.46%), the Smye (ER% = 22.22), and standard URR (ER% = 23.81). For Kt/V, the Daugirdas equation and the ANN were similar (ER% = 9.52 and 11.11). The single-pool Kt/V (Kt/V(sp)) > or = 1.4 (ERA recommended) produced an ER% = 7.94 and a false positive rate (FPR%) equal to that shown by the ANN (FPR% = 3.17). According to the current threshold limits for HD dose adequacy, the ANN was a reliable and accurate tool for URR monitoring, better than the Smye and the modified URR methods. The use of the ANN urea estimation yields accurate results when used to calculate Kt/V. The Kt/V(sp) with an adequacy threshold of 1.4 is a superior approach for HD adequacy monitoring, suggesting that the current adequacy limits should be reviewed for both URR and Kt/V.     

Development of a pilot telemedicine network for paediatric oncology in Brazil

We established a pilot telemedicine network for paediatric oncology in Brazil, linking the School of Medicine at the University of Sao Paulo in Sao Paulo City to the 'Hospital de Base' in Porto Velho, Rondonia, located in the Amazon region, 3,000 km away. The videoconferencing link used ISDN transmission at 384 kbit/s. The network was used for patient screening, follow-up, treatment monitoring and other activities. Between March 2000 and 2002, 69 videoconferences were held for 33 patients, 29 with cancer. During this period, 16 patients required transfer, 18 patients died and 11 achieved cancer remission. The main cause for patient mortality (infection) was not one that could be addressed directly by telemedicine. Using the School of Medicine as a benchmark, the average mortality rate for paediatric cancer patients in the pilot was higher. However, it was lower than previous levels observed at Rondonia (62% versus 80%).     

Effect of herpesvirus infection on pancreatic duct cell secretion

AIM: To examine the effect of acute infection caused by herpesvirus (pseudorabies virus, PRV) on pancreatic ductal secretion. METHODS: The virulent Ba-DupGreen (BDG) and nonvirulent Ka-RREpolacgfp (KEG) genetically modified strains of PRV were used in this study and both of them contain the gene for green fluorescent protein (GFP). Small intra/ interlobular ducts were infected with BDG virus (107 PFU/mL for 6 h) or with KEG virus (1010 PFU/mL for 6 h), while non-infected ducts were incubated only with the culture media. The ducts were then cultured for a further 18 h. The rate of HCO3- secretion [base efflux -J(B-)] was determined from the buffering capacity of the cells and the initial rate of intracellular acidification (1) after sudden blockage of basolateral base loaders with dihydro-4,4,-diisothiocyanatostilbene-2,2,-disulfonic acid (500 μmol/L) and amiloride (200 μmol/L), and (2) after alkali loading the ducts by exposure to NH4CI. All the experiments were performed in HCO3--buffered Ringer solution at 37℃ (n = 5 ducts for each experimental condition). Viral structural proteins were visualized by immunohistochemistry. Virallyencoded GFP and immunofluorescence signals were recorded by a confocal laser scanning microscope. RESULTS: The BDG virus infected the majority of accessible cells of the duct as judged by the appearance of GFP and viral antigens in the ductal cells. KEG virus caused a similarly high efficiency of infection. After blockage of basolateral base loaders, BDG infection significantly elevated -J(B-) 24 h after the infection, compared to the non-infected group. However, KEG infection did not modify -J(B-). After alkali loading the ducts, -J(B-) was significantly elevated in the BDG group compared to the control group 24 h after the infection. As we found with the inhibitor stop method, no change was observed in the group KEG compared to the non-infected group. CONCLUSION: Incubation with the BDG or KEG strains of PRV results in an effective infection of ductal epithelial cells. The BDG strain of PRV, which is able to initiate a lytic viral cycle, stimulates HCO3- secretion in guinea pig pancreatic duct by about four- to fivefold, 24 h after the infection. However, the KEG strain of PRV, which can infect, but fails to replicate, has no effect on HCO3- secretion. We suggest that this response of pancreatic ducts to virulent PRV infection may represent a defense mechanism against invasive pathogens to avoid pancreatic injury.     

Can we diagnose, treat or even understand neurally mediated syncope?

There are significant gaps in our understanding of the pathophysiology, diagnosis and treatment of NMS (neurally mediated syncope). Contributions in this area will be welcomed by patients and physicians taking care of them alike. In this issue of Clinical Science, Simek and co-workers report a novel non-invasive physiological measurement that does not require head-up tilt to diagnose NMS. However, validation studies applied to an unselected patient population are needed before we can judge how useful this test will be in the diagnosis of NMS.     

Load-related implant reaction of mini-implants used for orthodontic anchorage

Abstract: The purpose of this study was to determine the clinical and biomechanical outcome of two different titanium mini‐implant systems activated with different load regimens. A total of 200 mini‐implants (102 Abso Anchor^® and 98 Dual Top^®) were placed in the mandible of eight Göttinger minipigs. Two implants each were immediately loaded in opposite direction by various forces (100, 300 or 500 cN) through tension coils. Additionally, three different distances between the neck of the implant and the bone rim (1, 2 and 3 mm) were used. The different load protocols were chosen to evaluate the load‐related implant performance. The load was provided by superelastic tension coils, which are known to develop a virtually constant force. Non‐loaded implants were used as a reference. Following an experimental loading period of 22 and 70 days half of the minipigs were sacrificed, and implant containing bone specimens evaluated for clinical performance and implant stability. Implant loosing was found to be statistically dependent on the tip moment (TM) at the bone rim. Clinical implant loosing were only present when load exceeded 900 cN mm. No movement of implants through the bone was found in the experimental groups, for any applied loads. Over the two experimental periods the non‐loaded implants of one type of implant had a higher stability than those of the loaded implants. Dual Top^® implants revealed a slightly higher removal torque compared with Abso Anchor^® implants. Based on the results of this study, immediate loading of mini‐implants can be performed without loss of stability when the load‐related biomechanics do not exceed an upper limit of TM at the bone rim.     

Occurrence of Helicobacter pylori in dental plaque and saliva of dyspeptic patients

BACKGROUND: Helicobacter pylori infection in the stomach is associated with gastric and duodenal ulcers, gastric cancers and gastric lymphoma. The organism is transmitted by ingestion, but the oral-oral route and the fecal-oral route are also suggested. The prevalence of infection with H. pylori in developing countries, including Brazil, is higher than in developed countries. PURPOSE: This study aimed to evaluate the role of the oral cavity as a reservoir of this species, by evaluating the occurrence of H. pylori in supragingival dental plaque and in saliva of Brazilian dyspeptic patients, whether harboring the organism or not in the stomach. MATERIAL AND METHODS: Forty-nine patients reporting dyspeptic symptoms were subjected to oral clinical examination and collection of saliva and supragingival dental plaque samples prior to the endoscopic examination. The detection of H. pylori in oral samples was performed by PCR using 16S rRNA primers. The bacteria were detected in stomach by means of the rapid urease test. RESULTS: Helicobacter pylori was detected in the stomach of 20 of 49 subjects reporting dyspeptic symptoms. The organism was detected in only one supragingival plaque sample, obtained from a patient positive for the urease test in the stomach and in none of the salivary samples. CONCLUSION: Supragingival dental plaque and saliva may not be relevant reservoirs of H. pylori.