Abdominal compression: A new intraoperative maneuver to detect chyle fistulas during left neck dissections that include level IV

Background Chyle fistulas may occur after left neck dissections that include level IV, due to injury of the thoracic duct or of 1 of its major branches. Despite being unusual, this complication carries substantial postoperative morbidity and even mortality. So far, no effective intraoperative maneuver has been reported to detect this fistula at the end of a neck dissection. In this cohort study, we sought to describe a simple new maneuver, intraoperative abdominal compression, which can effectively help to identify an open major lymphatic duct on level IV at the end of a neck dissection. Patients and Methods From March 1989 to September 2010, 206 patients underwent neck dissections involving left level IV, and underwent intraoperative abdominal compression. There were 119 men and 87 women, with ages ranging from 18 to 81 years (median, 52 years). One hundred forty-four patients had squamous cell carcinomas, 54 had thyroid carcinomas, 5 had malignant melanomas, and 3 had salivary cancers. Distribution by type of left neck dissection was: selective including levels II, III, and IV (73 cases; 35.4%), selective including levels II, III, IV, and V (55 cases; 26.6%), selective including levels I, II, III, and IV (12 cases; 5.8%), modified radical (47 cases; 22.8%), and radical (19 cases; 9.2%). In all cases, at the end of the procedure, the endotracheal tube was temporarily disconnected from the ventilator. Keeping the dissected level IV area under clear visualization, an abdominal compression was performed. At this moment, any detected lymphatic leak was carefully clamped and tied with nonabsorbable sutures. After ventilating the patient, the intraoperative abdominal compression was repeated to reassure complete occlusion of the lymphatic vessel. Results In 13 cases (6.3%), a chyle leak was detected after performing the intraoperative abdominal compression. All leaks except for 2 were successfully controlled after 1 attempt. In these 2 patients, a patch of muscle and fat tissue was applied with fibrin glue on the top. In 1 of these patients, another chyle leak in a different location was detected only at the second intraoperative abdominal compression, and was also effectively closed. Postoperatively, there were 2 (1%) chyle fistulas, both among these 13 cases, and all were successfully managed with clinical measures only. No fistulas occurred among the remaining 193 patients in whom intraoperative abdominal compression did not demonstrate lymphatic leak. Conclusion To our knowledge, this is the first description of a specific maneuver to actively detect a lymphatic fistula at the end of a left neck dissection involving level IV. In this study, intraoperative abdominal compression was able to detect an open lymphatic vessel in 6.3% of the cases, as well as to assure its effective sealing in the remaining 93.7% of the patients. Moreover, no life-threatening high-volume fistula was noted in this study. (C) 2012 Wiley Periodicals, Inc. Head Neck, 2012

Renal GLUT1 reduction depends on angiotensin-converting enzyme inhibition in diabetic hypertensive rats

Aims: Angiotensin-converting enzyme (ACE) inhibitors are used in diabetic kidney disease to reduce systemic/intra-glomerular pressure. The objective of this study was to investigate whether reducing blood pressure (BP) could modulate renal glucose transporter expression, and urinary markers of diabetic nephropathy in diabetic hypertensive rats treated with ramipril or amlodipine. Main methods: Diabetes was induced in spontaneously-hypertensive rats (~210 g) by streptozotocin (50 mg/kg). Thirty days later, animals received ramipril 15 μg/kg/day (R, n =10), or amlodipine 10 mg/kg/day (A, n= 8,) or water (C, n = 10) by gavage. After 30-day treatment, body weight, glycaemia, urinary albumin and TGF-β1 (enzyme-linked immunosorbent assay) and BP (tail-cuff pressure method) were evaluated. Kidneys were removed for evaluation of renal cortex glucose transporters (Western blotting) and renal tissue ACE activity (fluorometric assay). Key findings: After treatments, body weight (p = 0.77) and glycaemia (p = 0.22) were similar among the groups. Systolic BP was similarly reduced (p < 0.001) in A and R vs. C (172.4 ± 3.2; 186.7 ± 3.7 and 202.2 ± 4.3 mm Hg; respectively). ACE activity (C: 0.903 ± 0.086; A: 0.654 ± 0.025, and R: 0.389 ± 0.057 mU/mg), albuminuria (C: 264.8 ± 15.4; A: 140.8 ± 13.5 and R: 102.8 ± 6.7 mg/24 h), and renal cortex GLUT1 content (C: 46.81 ± 4.54; A: 40.30 ± 5.39 and R: 26.89 ± 0.79 AU) decreased only in R (p < 0.001, p < 0.05 and p < 0.001; respectively). Significance:We concluded that the blockade of the renin–angiotensin systemwith ramipril reduced earlymarkers of diabetic nephropathy, a phenomenon that cannot be specifically related to decreased BP levels.

Two-Phase Frictional Pressure Drop and Flow Boiling Heat Transfer for R245fa in a 2.32-mm Tube

Experimental two-phase frictional pressure drop and flow boiling heat transfer results are presented for a horizontal 2.32-mm ID stainless-steel tube using R245fa as working fluid. The frictional pressure drop data was obtained under adiabatic and diabatic conditions. Experiments were performed for mass velocities ranging from 100 to 700 kg m−2 s−1 , heat flux from 0 to 55 kW m−2 , exit saturation temperatures of 31 and 41◦C, and vapor qualities from 0.10 to 0.99. Pressures drop gradients and heat transfer coefficients ranging from 1 to 70 kPa m−1 and from 1 to 7 kW m−2 K−1 were measured. It was found that the heat transfer coefficient is a strong function of the heat flux, mass velocity, and vapor quality. Five frictional pressure drop predictive methods were compared against the experimental database. The Cioncolini et al. (2009) method was found to work the best. Six flow boiling heat transfer predictive methods were also compared against the present database. Liu and Winterton (1991), Zhang et al. (2004), and Saitoh et al. (2007) were ranked as the best methods. They predicted the experimental flow boiling heat transfer data with an average error around 19%.

Two-phase flow patterns and pressure drop inside horizontal tubes containing twisted-tape inserts

This paper presents an experimental study on two-phase flow patterns and pressure drop of R134a inside a 15.9 mm ID tube containing twisted-tape inserts. Experimental results were obtained in a horizontal test section for twisted-tape ratios of 3, 4, 9 and 14, mass velocities ranging from 75 to 250 kg/m(2) s and saturation temperatures of 5 and 15 degrees C. An unprecedented discussion on two-phase flow patterns inside tubes containing twisted-tape inserts is presented and the flow pattern effects on the frictional pressure drop are carefully discussed. Additionally, a new method to predict the frictional pressure drop during two-phase flow inside tubes containing twisted-tape inserts is proposed. (C) 2012 Elsevier Ltd. All rights reserved.