Cause Of Constriction Research Articles

Retrospective computed tomography analysis of endotracheal tube constriction and mispositioning in cats and dogs

ObjectiveTo discover the prevalence of endotracheal tube (ETT) constriction and rostral and caudal mispositioning in anaesthetized cats and dogs, and to identify associated risk factors. Study designRetrospective analysis. AnimalsA total of 146 cats and 670 dogs. MethodsComputed tomography images of the head/neck/thorax from orotracheally intubated cats and dogs were visually assessed for constriction or mispositioning of the ETT. If constriction was present, measurements of the cross-sectional area (CSA) of the ETT lumen at constricted and un-constricted locations were compared. Location and cause of constriction were noted and the expected increase in resistance to gas flow was calculated. Animal information was collected from clinical records. Normality of continuous variables was assessed via the Shapiro–Wilk test. Chi-square tests examined associations between variables. Kendall’s tau-b test was performed between measured ETT size and degree of constriction. ResultsThe ETT extended rostrally beyond incisors in 52% of cases; the connector was within the oral cavity in 19% of cases. The ETT extended beyond the first rib in 25.5% of cases. The prevalence of ETT constriction was 22.7%. Median reduction in CSA was 7.68% (0.14–64.19%). Median increase in resistance assuming laminar and turbulent flow was 16.5% (0.3–680%) and 21% (0.3–1200%), respectively. The most common cause of constriction was the presence of a radiotherapy mouth gag. Significant associations existed between presence of constriction and rostral mispositioning, and caudal mispositioning and extreme brachycephaly. Increased severity of constriction was more likely in smaller ETT. Conclusions and clinical relevanceConstriction and mispositioning of ETT occurred very commonly in this population. Checking the ETT within the oral cavity for constriction and mispositioning is recommended. Radiotherapy mouth gags increase the risk of ETT compression. Smaller ETT are at greater risk of severe constriction. Brachycephalic dogs are at particular risk of caudal mispositioning.

Effect of Alcohol Consumption on the Frequency of Microsaccades

In recent years, as eye movement measurement devices have become relatively cheap, many attempts have been made to quantitatively evaluate covert attention by focusing on microsaccades. However, the measurement of microsaccades still has many unclear points, and a unified analysis method is still lacking. As such, the interpretation of results differs among different research groups. To solve this problem, it is important to conduct empirical studies on microsaccades to evaluate them using a unified method. In this study, we conducted an empirical experiment on the effects of alcohol consumption on microsaccades by temporarily suppressing cerebellar activity with alcohol consumption. The results showed that the frequency of microsaccades was significantly reduced after 30, 50, and 70 min of drinking compared to after drinking (p< 0.05). These results suggest that the decrease in brain function caused by alcohol consumption suppresses the frequency of microsaccades, and that this may be the cause of constriction in the peripheral visual field when drinking.

Role of thermal effects in neon and argon constricted discharges

The paper is aimed at investigating the role of inhomogeneous heating of the neutral gas in a constricted glow discharge in neon and argon. It is shown that inhomogeneous heating is not the primary cause of constriction in specified gases at pressures of tens and hundreds Torr cm and reduced currents not exceeding 100–200 mA cm−1. Constriction of the positive column occurs even with an insignificant gas heating in a pulsed regime. An abrupt constriction is caused by the nonlinear dependence of the ionization number on the electron density. In mentioned discharge conditions the frequency of electron–electron collisions is comparable to the electron energy relaxation frequency due to elastic electron-atom collisions. Thermal effects play a secondary role in the formation of a constricted discharge. At the same time, inhomogeneous gas heating in argon is more notable than in neon. Unlike neon, stationary argon discharge loses spatial stability in a vertically oriented tube as the pressure and current increase and a buoyancy effect takes place in a horizontal orientation. Such difference in the behavior of constricted neon and argon discharges is mainly caused by the difference in shape of elastic electron-atom collision cross sections. Interferometric methods allowed to study the temperature field of neutral atoms, dynamics of both gas heating and ascent of constricted cord. Observed effects are interpreted on the basis of the heat equation and the Navier–Stokes equation. Comparison of experimental and theoretical results shows good agreement.

Constrictive pericarditis: Detection of mycobacterium tuberculosis in paraffin-embedded pericardial tissues by polymerase chain reaction

Background: Although the utility of polymerase chain reaction (PCR) for diagnosis of acute pleuro-pericardial tuberculosis has been well established, its use for chronic constrictive pericarditis is yet to be reported. Aims: To define the sensitivity and specificity of PCR for diagnosis of tuberculosis (TB) in patients with constrictive pericarditis. Methods: The medical records of 30 consecutive patients with constrictive pericarditis were reviewed. In addition their historical paraffin-embedded pericardial tissues were used for new histopathologic examination and PCR amplification for Mycobacterium tuberculosis genome. Results: There were 23 males and 7 females with a mean age of 35 ± 19.5 years. The anticipated causes of constriction included idiopathic ( n = 21), tuberculosis ( n = 5), cardiac surgery ( n = 2) and post traumatic ( n = 2). PCR became positive in nine patients. Four out of 5 patients with tuberculous granuloma had a positive test result. In addition all 4 patients with non-tuberculous constrictive pericarditis had a negative test result. Therefore considering the presence or absence of granuloma as a diagnostic criteria, the sensitivity and specificity of PCR were 4/5 (80%) and 20/25 (80%), respectively.

Invited commentary

Invited commentary

Experimental paralysis of tensor veli palatini muscle.

In an effort to study the effects of experimental paralysis of tensor veli palatini (TVP) muscle on Eustachian tube (ET) function and middle-ear (ME) status, botulinum toxin A (Oculinum) was injected into the TVP muscles of 8 Rhesus monkeys. Tubal function was tested longitudinally in 2 animals with tympanostomy tubes using the forced-response test, while in the remaining 6 animals; ME condition was documented daily using tympanometry. The postinjection tubal function was characterized by abolished active muscular function and decreased closing pressure. Activity associated with tubal dilations gradually reappeared by the fifth week. The lack of lumen constrictions following injection suggested that the TVP muscle is the cause of constriction as well as normal dilation. In 6 animals with intact tympanic membranes, 10 of the 12 ears developed flat tympanograms associated with otitis media with effusion (OME) within 8-30 days of injection and serous effusions were recovered by tympanocentesis in seven ears. These results show that a non-traumatic reversible functional obstruction of the ET was created by injecting botulinum toxin A into the TVP muscle. This functional obstruction was associated with the development of high negative ME pressure and serous effusion.

On the surgical treatment of pyelo-ureteral junction strictures.

The observations covered 151 cases of hydronephrosis caused by stricture of the pyelo-ureteral junction. The causes of constriction were in 62 cases accessory vessels, in 49 intrinsic stenosis, in 29 surgical lesions, traumas and inflammatory changes, in 23 adhesions, scars and fibrous bands, in 12 cases abnormal ureteral origin, and in 7 cases other factors. In some patients, urinary outflow was hindered by 2 or more factors. Various surgical methods were used. Control examinations were carried out 1–14 years after operation. It appears from the presented material that in cases of accessory vessels, adhesions, scars and fibrous bands the surgical procedure should be chosen individually, depending on the anatomical situation. In cases of non-complicated hydronephrosis the best results are obtained by the Anderson-Hynes operation, while in others by intubated ureterotomy (Davis).