Pharmacodynamics of Phenobarbital Anesthesia and Pentylenetetrazol-Induced Maximal Seizures in a Rat Model of Neoplastic Spinal Cord Compression

The purpose of this investigation was to determine whether paraplegia induced by neoplastic cord compression affects the pharmacodynamics of phenobarbital general anesthesia or of pentylenetet-razol (PTZ)-induced convulsions. Paraplegic rats harboring a thora-columbar epidural tumor, or an identical hindlimb tumor mass, received an i.v. infusion of phenobarbital until the onset of anesthesia. At that point, the phenobarbital concentrations in the CSF and serum were measured. Similarly, PTZ was infused until the onset of maximal seizures. It was found that changes related to systemic tumor growth and newly developed paraplegia due to neoplastic spinal cord compression did not attenuate the pharmacodynamics of phenobarbital. However, sustained paraplegia of 4 days duration reduced CNS sensitivity to the hypnotic action of the barbiturate as evidenced by the higher cerebrospinal fluid phenobarbital concentration required to induce anesthesia (170 ± 31 vs 125 ± 20 mg/L; P < 0.05). On the other hand, sustained paraplegia did not affect brain threshold concentration for PTZ-induced seizures.     

Measurement of basal tear turnover using a standardized protocol

Background: The aim of this study was to compare basal tear turnover values of healthy volunteers in different countries. Methods: Healthy volunteers aged between 20 and 70 years were selected in three European cities. Basal tear turnover values were calculated according to a standardized protocol from the decay of the fluorescein concentration in tears after instillation of 1-l drop of fluorescein in the conjunctival sac. Fluorescein concentration was measured with identical commercial fluorophotometers. A monoexponential decay of fluorescein was assumed to represent basal tear flow. Results: The mean tear turnover values were 13.1%/ min ± 4.6 SD (n=4), 16.0%/ min ± 5.2 SD (n=24) and 17.5%/ min ± 3.4 SD (n = 20) in Clermont-Ferrand (France), Leiden (The Netherlands) and Madrid (Spain), respectively. The differences between the values were not significant (Mann-Whitney test P > 0.09). Conclusions: The tear turnover in the different cities was similar. The methods used were simple and the software easy to use.Concerted Action, supported in part by the European Commission, on Ocular Fluorometry: Standardization and Instrumentation Development of the 4th European Community Medical and Health Research Programme (No. MR 4*/0314/P).     

Cross-sectional study of intestinal parasites and Chagas' disease in the Municipality of Novo Air?o, State of Amazonas, Brazil]

A cross-sectional study was performed on the residents of one in every ten households in the town of Novo Air?o, in the northern meso-region of the State of Amazonas, 250 kilometers from Manaus by riverboat. A family cluster sample of 89 dwellings was studied. A stool sample was requested from each of the inhabitants for examination using the Lutz sedimentation and Baermann-Moraes-Coutinho techniques, and blood was taken by venous puncture for Trypanosoma cruzi Elisa antibody testing and immunofluorescence. From a total of 316 stool samples, 87.6% had one or more parasites: Ascaris lumbricoides (35.1%), Entamoeba histolytica (29.1%), Giardia lamblia (17.4%), and other parasites with lower prevalence rates. These results were directly correlated with lack of sanitation and clean water supply. Of the 346 sera examined, 16 (4.6%) were reactive to T. cruzi antibodies, but only three showed a correlation between this result and human contact with wild triatomines, known locally as "piassava lice".     

Catheter entrapment by atrial suture during minimally invasive port-access cardiac surgery

PURPOSE: The port-access approach allows surgeons to perform heart operations through small intercostal openings, or "ports". This technique requires new skills for anesthesiologists. A pulmonary artery venting (PAV) catheter and, in some cases, a coronary sinus catheter (for administration of retrograde cardioplegia) are positioned with the aid of fluoroscopy and transesophageal echography (TEE). Both catheters have a wider diameter than the more commonly used conventional PA catheter and present distinctive features. We report a case in which a pulmonary artery venting catheter was entrapped by a suture during a port-access procedure. CLINICAL FEATURES: A 35-yr-old man with severe mitral valve insufficiency was scheduled for valve repair. After a successful bypass procedure, resistance was felt while attempting to withdraw the PAV catheter. On fluoroscopy, fixation of the catheter at the heart level was established and perforation by suture was confirmed after injection of a contrast agent. Because of the risk of cardiac wall rupture and tamponade, the thorax was reopened. After release of some atrial sutures, the catheter could be withdrawn easily. Transfixion by a suture was confirmed by visual examination. CONCLUSION: The more frequent use of a PAV catheter in minimally invasive cardiac surgery with the port-access technique should remind the anesthesiologist of the higher risk of entrapment by surgical sutures. Surgeons should be aware of the risk of accidentally transfixing this catheter during closure of the atriotomy via the port.     

Ultrasound Densitometric Analysis: Comparison Between an Online Digital Acquisition Acoustic Program and an Offline Analog Program

Videodensitometric analysis of myocardial contrast echocardiography is traditionally performed off line. Recently, an online contrast ultrasound analysis system, Acoustic Densitometry (Hewlett-Packard), was introduced. We compared pixel intensities acquired with Acoustic Densitometry to pixel intensities derived from videodensitometry. A tissue phantom was imaged in phase I using three transducer frequencies (2.5, 3.5, and 5.0 MHz). In phase II, an in vitro flowing tube model with various concentrations of Albunex® was imaged at two flow rates, 0.6 and 1.2 m/sec, and at two transducer frequencies, 2.5 and 3.5 MHz. The relationship between pixel intensities yielded by the two systems for identical ultrasound signals was determined with linear regression. Intensities derived with Acoustic Densitometry strongly correlated with those derived from the offline videodensitometry system. The intensities were related by a predictive multiplicative factor based on display characteristics of the two systems. These results suggest that semiquantitative, online perfusion analysis with Acoustic Densitometry is as sensitive as analysis offline with videodensitometry.