Non-equilibrium relaxation and interface energy of the Ising model

{}From the non-equilibrium critical relaxation study of the two-dimensional Ising model, the dynamical critical exponent $z$ is estimated to be $2.165 \pm 0.010$ for this model. The relaxation in the ordered phase of this model is consistent with $\exp (-\sqrt{t/\tau })$ behavior. The interface energy of the three-dimensional Ising model is studied and the critical exponent of the correlation length $\nu$ and the critical amplitude of the surface tension $\sigma_0$ are estimated to be $0.6250\pm 0.025$ and $1.42\pm 0.04$, respectively. A dynamic Monte Carlo renormalization group method is applied to the equilibrium properties of the three-dimensional Ising model successfully.Comment: 32pages( 15 figures are not included. Their Postscript file is available. Request the author directly. ), LaTe

Plasma pro-atrial natriuretic peptide to estimate fluid balance during open and robot-assisted esophagectomy:a prospective observational study

Abstract Background It remains debated how much fluid should be administered during surgery. The atrial natriuretic peptide precursor proANP is released by atrial distension and deviations in plasma proANP are reported associated with perioperative fluid balance. We hypothesized that plasma proANP would decrease when the central blood volume is compromised during the abdominal part of robot-assisted hybrid (RE) esophagectomy and that a positive fluid balance would be required to maintain plasma proANP. Methods Patients undergoing RE ( n \u2009=\u200925) or open (OE; n \u2009=\u200925) esophagectomy for gastroesophageal cancer were included consecutively in this prospective observational study. Plasma proANP was determined repetitively during esophagectomy to allow for distinction between the abdominal and thoracic part of the procedure. The RE group was 15\ub0 head up tilted during the abdominal procedure. Results The blood loss was 250 (150\u2013375) (RE) and 600\ua0ml (390\u2013855) (OE) ( p \u2009=\u20090.01), but the two groups of patients were provided with a similar positive fluid balance: 1705 (1390\u20131983) vs. 1528\ua0ml (1316\u20131834) ( p \u2009=\u20090.4). However, plasma proANP decreased by 21% ( p \u2009<\u20090.01) during the abdominal part of RE carried out during moderate head-up tilt, but only by 11% ( p \u2009=\u20090.01) during OE where the patients were supine. Plasma proANP and fluid balance were correlated in the RE-group ( r \u2009=\u20090.5 (0.073\u20130.840), p \u2009=\u20090.02) and tended to correlate in the OE group ( r \u2009=\u20090.4 (\u22120.045\u20130.833), p \u2009=\u20090.08). Conclusion The results support that plasma proANP decreases when the central blood volume is compromised and suggest that an about 2200\ua0ml surplus administration of crystalloid is required to maintain plasma proANP during esophagectomy. Trial registration Clinicaltrials.gov ( NCT02077673 ). Registered retrospectively February 12 th 2014

Plasma pro-atrial natriuretic peptide to estimate fluid balance during open and robot-assisted esophagectomy:a prospective observational study

BACKGROUND: It remains debated how much fluid should be administered during surgery. The atrial natriuretic peptide precursor proANP is released by atrial distension and deviations in plasma proANP are reported associated with perioperative fluid balance. We hypothesized that plasma proANP would decrease when the central blood volume is compromised during the abdominal part of robot-assisted hybrid (RE) esophagectomy and that a positive fluid balance would be required to maintain plasma proANP. METHODS: Patients undergoing RE (n = 25) or open (OE; n = 25) esophagectomy for gastroesophageal cancer were included consecutively in this prospective observational study. Plasma proANP was determined repetitively during esophagectomy to allow for distinction between the abdominal and thoracic part of the procedure. The RE group was 15° head up tilted during the abdominal procedure. RESULTS: The blood loss was 250 (150–375) (RE) and 600 ml (390–855) (OE) (p = 0.01), but the two groups of patients were provided with a similar positive fluid balance: 1705 (1390–1983) vs. 1528 ml (1316–1834) (p = 0.4). However, plasma proANP decreased by 21% (p < 0.01) during the abdominal part of RE carried out during moderate head-up tilt, but only by 11% (p = 0.01) during OE where the patients were supine. Plasma proANP and fluid balance were correlated in the RE-group (r = 0.5 (0.073–0.840), p = 0.02) and tended to correlate in the OE group (r = 0.4 (−0.045–0.833), p = 0.08). CONCLUSION: The results support that plasma proANP decreases when the central blood volume is compromised and suggest that an about 2200 ml surplus administration of crystalloid is required to maintain plasma proANP during esophagectomy. TRIAL REGISTRATION: Clinicaltrials.gov (NCT02077673). Registered retrospectively February 12(th) 2014

Robot-Assisted Hybrid Esophagectomy Is Associated with a Shorter Length of Stay Compared to Conventional Transthoracic Esophagectomy:A Retrospective Study

Aim. To compare the peri- and postoperative data between a hybrid minimally invasive esophagectomy (HMIE) and the conventional Ivor Lewis esophagectomy. Methods. Retrospective comparison of perioperative characteristics, postoperative complications, and survival between HMIE and Ivor Lewis esophagectomy. Results. 216 patients were included, with 160 procedures performed with the conventional and 56 with the HMIE approach. Lower perioperative blood loss was found in the HMIE group (600 ml versus 200 ml, p<0.001). Also, a higher median number of lymph nodes were harvested in the HMIE group (median 28) than in the conventional group (median 23) (p=0.002). The median length of stay was longer in the conventional group compared to the HMIE group (11.5 days versus 10.0 days, p=0.03). Patients in the HMIE group experienced fewer grade 2 or higher complications than the conventional group (39% versus 57%, p=0.03). The rate of all pulmonary (51% versus 43%, p=0.32) and severe pulmonary complications (38% versus 18%, p = 0.23) was not statistically different between the groups. Conclusions. The HMIE was associated with lower intraoperative blood loss, a higher lymph node harvest, and a shorter hospital stay. However, the inborn limitations with the retrospective design stress a need for prospective randomized studies. Registration number is DRKS00013023

Thoracic epidural analgesia reduces gastric microcirculation in the pig

BACKGROUND: Thoracic epidural analgesia (TEA) is used for pain relief during and after abdominal surgery, but the effect of TEA on the splanchnic microcirculation remains debated. We evaluated whether TEA affects splanchnic microcirculation in the pig. METHODS: Splanchnic microcirculation was assessed in nine pigs prior to and 15 and 30 min after induction of TEA. Regional blood flow was assessed by neutron activated microspheres and changes in microcirculation by laser speckle contrast imaging (LSCI). RESULTS: As assessed by LSCI 15 min following TEA, gastric arteriolar flow decreased by 22 % at the antrum (p = 0.020) and by 19 % at the corpus (p = 0.029) of the stomach. In parallel, the microcirculation decreased by 19 % at the antrum (p = 0.015) and by 20 % at the corpus (p = 0.028). Reduced arteriolar flow and microcirculation at the antrum was confirmed by a reduction in microsphere assessed regional blood flow 30 min following induction of TEA (p = 0.048). These manifestations took place along with a drop in systolic blood pressure (p = 0.030), but with no significant change in mean arterial pressure, cardiac output, or heart rate. CONCLUSION: The results indicate that TEA may have an adverse effect on gastric arteriolar blood flow and microcirculation. LSCI is a non-touch technique and displays changes in blood flow in real-time and may be important for further evaluation of the concern regarding the effect of thoracic epidural anesthesia on gastric microcirculation in humans. TRIAL REGISTRATIONS: Not applicable, non-human study