Objective To confirm the difference between internal and external pressure of cervical esophageal and to discuss the relations between cervical esophageal pressure difference with the formation of cervical anastomotic leakage. Methods In the present study, 12 New Zealand white rabbits were used. We applied a pressure transducer to describe the variation of pressure of intrathoracic, thoracic esophagus, cervical esophagus and upper esophageal sphincter during resting and cough. Pressure value was recorded and read through MD3000 system. And the difference between each point was analyzed. Results The pressures resulting from the cough induced were significantly higher in intrathoracic than in thoracical esophagous (10.2±0.6 cm H2O vs. 36.7±1.0 cm H2O), exhibited significantly higher in upper esophageal sphincter and thoracic esophagous than in cervical esophageal (7.5±0.2 cm H2O vs. 12.0±0.4 cm H2O, vs. 10.2±0.6 cm H2O). Conclusion Cervical anastomotic leaks are affected by many factors.And the most notabe one is the constant pressure from inside-out around cervical anastomotic.
A set of device for the in vivo measurement of the pressure difference between the anterior and the posterior chambers (PDAP) was designed to investigate the temporal varying rules of PDAP in the anterior segment of rabbit eyes. A platform was established for the in vivo measurement of PDPA according to the mechanism of joint implement. Rabbit models with high intraocular pressure (IOP) were constructed by means of injecting Carbomer into anterior chamber to increase IOP. The in vivo 24 hours continuous measurements of PDAP were performed for normal rabbit eye and eye with high IOP. The developed device could sensitively response to the small pressure difference in eye. The pressure difference in the normal rabbit eye varied with time, and the variation range during a whole day was 5.84–96.84 Pa which reflected the existence of physiological rule. For the rabbit eye with high IOP, pressure in anterior chamber was higher than that in posterior chamber which was in consistence with the theory of self-adaptation adjustment. The present study indicates that the approaches and device designed in this paper can well implement the measurement of PDAP as well as the temporal varying rules of PDAP in the anterior segment during a whole day.
This study aims to explore the intraventricular pressure difference (IVPD) within left ventricle in patients with paroxysmal atrial fibrillation (PAF) by using the relative pressure imaging (RPI) of vector flow mapping (VFM). Twenty patients with paroxysmal atrial fibrillation (PAF) and thirty control subjects were enrolled in the study. Systolic and diastolic IVPD derived from VFM within left ventricle and conventional echocardiographic parameters were analyzed. It was found that the B-A IVPD of left ventricle in PAF patients showed the same pattern as controls—single peak and single valley during systole and double peaks and double valleys during diastole. Basal IVPD was the main component of base to apex IVPD (B-A IVPD). The isovolumetric systolic IVPD was associated with early systolic IVPD, early systolic IVPD was associated with late systolic IVPD, and late systolic IVPD was associated with isovolumic diastolic IVPD (all P < 0.05). The B-A IVPD and basal IVPD during isovolumetric systole, early systole, late systole and isovolumetric diastole in PAF patients significantly decreased (all P < 0.05). The study shows that the B-A IVPD pattern of the PAF group is the same as controls, but systolic B-A IVPD and basal IVPD are significantly reduced in PAF patients. VFM-derived RPI can evaluate left ventricular IVPD in PAF patients, providing a visually quantitative method for evaluating left ventricular hemodynamic mechanics in the patients with PAF.
Foam stability affects the efficacy and incidence of side effects of foam sclerotherapy. Exploring the relationship between foam pressure difference and foam stability can provide ideas and basis for obtaining more stable foam. In the experiment, sodium cod liver oleate foam was selected, and poloxamer 188 (concentration of 0%, 4%, 8%, 12%) was added to realize the change of foam pressure. By using the self-written program to process the foam pictures, the foam pressure difference and the relationship between the foam stability indicators (water separation rate curve, half-life) and the foam pressure difference were obtained. The results showed that at first the foam pressure increased with the increase of the concentration, and then it decreased with the increase of the concentration and reached a peak at the concentration of 4%. The foam pressure difference decreases continuously with the increase of decay time. When the additive concentration is low, the foam average pressure difference increases. And if the additive concentration is too high, the foam average pressure difference decreases. The smaller the foam pressure difference is, the better the foam stability is. This paper lays a foundation for the research on the stability of foam hardener.