Venous return is a major determinant of cardiac output. Adjustments within the venous system are critical for maintaining venous pressure during loss in circulating volume. This article reviews two factors that are thought to enable the venous system to compensate during acute hemorrhage: 1) changes in venous elastance and 2) mobilization of unstressed blood volume into stressed blood volume. We show that mobilization of unstressed blood volume is the predominant and more effective mechanism in preserving venous pressure. Preservation of mean circulatory filling pressure helps sustain venous return and thus cardiac output during significant hemorrhage.

Developing an effective and sustainable method for separating and purifying oily wastewater is a significant challenge. Conventional separation membrane and sponge systems are limited in their long-term usage due to weak antifouling abilities and poor processing capacity for systems with multiple oils. In this study, we present a dual-bionic superwetting gears overflow system with liquid steering abilities, which enables the separation of oil-in-water emulsions into pure phases. This is achieved through the synergistic effect of surface superwettability and complementary topological structures. By applying the surface energy matching principle, water and oil in the mixture rapidly and continuously spread on preferential gear surfaces, forming distinct liquid films that repel each other. The topological structures of the gears facilitate the overflow and rapid transfer of the liquid films, resulting in a high separation flux with the assistance of rotational motion. Importantly, this separation model mitigates the decrease in separation flux caused by fouling and maintains a consistently high separation efficiency for multiple oils with varying densities and surface tensions.

Background We studied the incidence of perioperative complications in patients presenting with a posterior mediastinal mass and the possible predictors of complications in these patients. Methods We conducted a review of the perioperative records of patients aged over 18 years with a posterior mediastinal mass confirmed by computed tomography (CT) who were admitted for surgical procedures relating to the mass during [2004][2005][2006][2007][2008][2009][2010][2011][2012][2013][2014]. Perioperative complications were defined as 1) hypoxemia (pulse oximetry \ 90% at a fraction of inspired oxygen of 1.0), 2) difficult ventilation (peak pressure [ 40 cm H 2 O or respiratory acidosis with P a CO 2 [ 60 mmHg), and 3) hemodynamic instability (systolic pressure\70 mmHg, pulse rate\40 beatsÁminand/or [ 120 beatsÁmin -1 for over five minutes). The review also extended to the first 24 hr postoperatively for cardiovascular and respiratory instability. Results Forty-three patients underwent 44 procedures, and the surgery entailed resection of the mediastinal mass in all but one patient. All patients received general anesthesia following intravenous induction. In 43 of 44 cases, intubation was achieved uneventfully with direct laryngoscopy after neuromuscular blockade. The incidence of perioperative cardiopulmonary complications was seven of 44 (16%) procedures. Four of these involved severe hypoxemia, two concerned hemodynamic instability, and two led to postoperative respiratory distress. No cardiovascular collapse or complete airway occlusion occurred. All occurrences of intraoperative complications transpired mid-surgery -six of the seven with the patient in the lateral position. Patients who developed complications were more likely to have a mass with a larger diameter and evidence of airway compression on the preoperative CT scan. Conclusion The incidence of perioperative complications in patients with a posterior mediastinal mass is not insignificant; however, no catastrophic airway or cardiopulmonary event was encountered in this study. Résumé

BACKGROUND: The perioperative assessment of right ventricular (RV) function remains a challenge. Tricuspid annular plane systolic excursion (TAPSE) using M-mode is a widely used measure of RV function. However, accurate alignment of the ultrasound beam with the direction of annular movement can be difficult with transesophageal echocardiography (TEE) to measure TAPSE, precluding effective use of M-mode to measure annular excursion. Tracking of specular reflectors in the myocardium may provide an angle-independent method to assess annular motion with TEE. We hypothesized that TEE speckle tracking of the lateral tricuspid annular motion represents a comparable measurement to the well-validated M-mode TAPSE on transthoracic echocardiogram (TTE), and may be considered as a reasonable alternative to TAPSE. METHODS: This is a prospective, observational cohort study. We included all patients, who were in sinus rhythm, with a preoperative TTE within 3 months of scheduled cardiac surgery that required intraoperative TEE. Tissue motion annular displacements (TMAD) of the lateral (L), septal (S), and midpoint (M) tricuspid annulus were measured (QLAB Cardiac Motion Quantification; Philips Medical, Andover, MA) after induction of general anesthesia. This was compared to the preoperative M-mode TAPSE on TTE. RESULTS: Seventy-two consecutive patients who met eligibility requirements were enrolled from September to November 2016. Twelve were excluded due to poor image quality, allowing TMAD to be analyzed in 60 patients. TMAD was analyzed offline and TMAD analysis was able to track tricuspid annular motion in all patients. The mean TMAD (L), TMAD (S), and TMAD (M) were 17.4 ± 5.2, 10.2 ± 4.8, and 14.2 ± 4.8 mm, respectively. TMAD (L) showed close correlation with M-mode TAPSE on TTE (r = 0.87, 95% confidence interval, 0.79–0.92; P < .01). All patients with a preoperative TAPSE <17 mm had a TMAD (L) <17 mm, while 71% of those with a TAPSE ≥ 17 mm had a TMAD (L) ≥ 17 mm. There was strong positive correlation between TMAD (L) and intraoperative RV fractional area change (r = 0.86, 95% confidence interval, 0.77–0.91; P < .01). Reproducibility analysis of TMAD within and across observers showed excellent correlation. CONCLUSIONS: TMAD is a quick and angle-independent method to quantitatively assess RV longitudinal function by TEE. It correlates strongly with M-mode TAPSE on TTE. Because TMAD and TAPSE were not simultaneously measured in this study, their correlation is subject to differences in loading conditions, general anesthesia, and changes in the disease process. TMAD may be easily applied in routine clinical settings and its role in the perioperative environment deserves to be further explored.