Buckling behavior of flat and cylindrical shells including through-the-thickness crack (through crack) is examined employing an effective reproducing kernel (RK) meshfree method. The concept of ...convected coordinate system is adopted to deal with general curvilinear surfaces. Both field variables and shell geometry are approximated by RKs, which is conceptually same procedure with isoparametric Finite Element Method (FEM). Each node has five degrees of freedom (DOFs). The numerical integration of stiffness matrices is conducted by strain smoothing approaches. In the present study, a crack modeling is introduced into the curved shell geometry for analyzing cracked cylinder buckling problems effectively. The presented approach has an attractive feature, i.e., five DOFs cracked flat shell model is only required for analyzing three-dimensional (3D) cracked curved shell problems. The accuracy and effectiveness of the present method are critically examined through several numerical examples in which the obtained results are compared with reference solutions as well as with the results of commercial FEM package (ANSYS). Effects of the element types in the FEM computations are also examined by comparison of the results by linear and quadratic shell elements. The results shed light on the significant effects of considered configurations on buckling coefficients and mode shapes.
Background
Evidence indicates that low-pressure pneumoperitoneum (PNP) reduces postoperative pain and analgesic consumption. A lower insufflation pressure may hamper visibility and working space. The ...aim of the study is to investigate whether deep neuromuscular blockade (NMB) improves surgical conditions during low-pressure PNP.
Methods
This study was a blinded randomized controlled multicenter trial. 34 kidney donors scheduled for laparoscopic donor nephrectomy randomly received low-pressure PNP (6 mmHg) with either deep (PTC 1–5) or moderate NMB (TOF 0–1). In case of insufficient surgical conditions, the insufflation pressure was increased stepwise. Surgical conditions were rated by the Leiden-Surgical Rating Scale (L-SRS) ranging from 1 (extremely poor) to 5 (optimal).
Results
Mean surgical conditions were significantly better for patients allocated to a deep NMB (SRS 4.5 versus 4.0;
p
< 0.01). The final insufflation pressure was 7.7 mmHg in patients with deep NMB as compared to 9.1 mmHg with moderate NMB (
p
= 0.19). The cumulative opiate consumption during the first 48 h was significantly lower in patients receiving deep NMB, while postoperative pain scores were similar. In four patients allocated to a moderate NMB, a significant intraoperative complication occurred, and in two of these patients a conversion to an open procedure was required.
Conclusions
Our data show that deep NMB facilitates the use of low-pressure PNP during laparoscopic donor nephrectomy by improving the quality of the surgical field. The relatively high incidence of intraoperative complications indicates that the use of low pressure with moderate NMB may compromise safety during LDN. Clinicaltrials.gov identifier: NCT 02602964.
Background
The use of low intra-abdominal pressure (<10 mmHg) reduces postoperative pain scores after laparoscopic surgery.
Objective
To investigate whether low-pressure pneumoperitoneum with deep ...neuromuscular blockade improves the quality of recovery after laparoscopic donor nephrectomy (LDN).
Design, setting and participants
In a single-center randomized controlled trial, 64 live kidney donors were randomly assigned to 6 or 12 mmHg insufflation pressure. A deep neuromuscular block was used in both groups. Surgical conditions were rated by the five-point Leiden-surgical rating scale (L-SRS), ranging from 5 (optimal) to 1 (extremely poor) conditions. If the L-SRS was insufficient, the pressure was increased stepwise.
Main outcome measure
The primary outcome measure was the overall score on the quality of recovery-40 (QOR-40) questionnaire at postoperative day 1.
Results
The difference in the QOR-40 scores on day 1 between the low- and standard-pressure group was not significant (
p
= .06). Also the overall pain scores and analgesic consumption did not differ. Eight procedures (24%), initially started with low pressure, were converted to a standard pressure (≥10 mmHg). A L-SRS score of 5 was significantly more prevalent in the standard pressure as compared to the low-pressure group at 30 min after insufflation (
p
< .01).
Conclusions
Low-pressure pneumoperitoneum facilitated by deep neuromuscular blockade during LDN does not reduce postoperative pain scores nor improve the quality of recovery in the early postoperative phase. The question whether the use of deep neuromuscular blockade during laparoscopic surgery reduces postoperative pain scores independent of the intra-abdominal pressure should be pursued in future studies.
Trial registration
The trial was registered at clinicaltrial.gov before the start of the trial (NCT02146417).
Although both delayed umbilical cord clamping and intact umbilical cord milking (I-UCM) provide the effective placental transfusion at birth, these procedures may not be used in neonates needing ...resuscitation. The aim of this study is to investigate the effect of cut umbilical cord milking (C-UCM), which permits resuscitation during an immediate transition period (ITP).
Sixty-two healthy term infants were randomly divided into C-UCM and I-UCM groups at birth. Approximately 30-cm length of cord was milked towards the baby 2-4 times within 20 seconds after birth in both C-UCM and I-UCM groups while the umbilical cord was cut in the former, and intact in the latter. Heart rate, arterial oxygen saturation (SpO
2
), cerebral regional oxygen saturation (crSO
2
) (2nd-15th min), blood pressure (BP) (within 15-30 min), residual placental blood volume (RPBV), and hemoglobin levels (at the sixth hour) were monitored during ITP.
There were no significant differences in terms of mean gestational age (w) (39.0 ± 1.2) versus (38.8 ± 1.1), birth weight (g) (3351.45 ± 254.30) versus (3256.94 ± 285.52), Apgar scores at the 5th min (10 ± 0 versus 10 ± 0), first breathing time (sec) (5.4 ± 3.8 versus 5.7 ± 4.1), SpO
2
, crSO
2
, BP (mmHg) (52.9 ± 6.9) versus (51.8 ± 5.7), hemoglobin levels (g/dl) (17.7 ± 1.8) versus (18.4 ± 1.4), and RPBV (ml/kg) (23.9 ± 4.7) versus (22.9 ± 5.4) between C-UCM and I-UCM groups (p > .05).
This study showed that C-UCM is as effective as I-UCM on cerebral oxygenation, hemodynamic and hematological adaptation of term infants in ITP. We suggest that C-UCM can provide additional placental transfusion in term neonates exposed to early cord clamping.
Chronic hyperglycemia causes structural alterations of proteins through the Maillard reaction. In diabetes, methylglyoxal (MGO)-induced hydroimidazolones are the predominant modification. In contrast ...to acute hyperglycemia, mitochondrial respiration is depressed in chronic diabetes. To determine whether MGO-derived protein modifications result in abnormalities in mitochondrial bioenergetics and superoxide formation, proteomics and functional studies were performed in renal cortical mitochondria isolated from rats with 2, 6, and 12 mo of streptozotocin-induced diabetes. MGO-modified proteins belonged to the following two pathways: 1) oxidative phosphorylation and 2) fatty acid beta-oxidation. Two of these proteins were identified as components of respiratory complex III, the major site of superoxide production in health and disease. Mitochondria from rats with diabetes exhibited a diminution of oxidative phosphorylation. A decrease in the respiratory complex III activity was significantly correlated with the quantity of MGO-derived hydroimidazolone present on mitochondrial proteins in both diabetic and control animals. In diabetes, isolated renal mitochondria produced significantly increased quantities of superoxide and showed evidence of oxidative damage. Administration of aminoguanidine improved mitochondrial respiration and complex III activity and decreased oxidative damage to mitochondrial proteins. Therefore, posttranslational modifications of mitochondrial proteins by MGO may represent pathogenic events leading to mitochondria-induced oxidative stress in the kidney in chronic diabetes.
The combined effect of external magnetic field and surface modification on boiling heat transfer of ferrofluids was investigated in this study. Experiments were performed on suspensions of Fe3O4 ...nanoparticles (volume fraction of 0.025% vf%) with and without presence of magnetic field on structured (surfaces with artificial cavities) hydrophilic and hydrophobic surfaces. Surface related effects such as the hole diameter, pitch size and surface wettability on boiling heat transfer were revealed using the high speed camera system. According to the obtained results, application of magnetic field enhanced boiling heat transfer. The effect of magnetic field was more pronounced on surfaces with larger pitch sizes. Magnetic field promoted bubble nucleation on the superheated surfaces by generating an additional force via Fe3O4 nanoparticles, resulting in enhanced bubble-bubble interactions and coalescence. Furthermore, the surfaces with the larger cavity diameter performed better in terms of heat transfer. Scanning Electron Microscopy (SEM) images showed that as the cavity diameter decreased, deposited nanoparticles tended to completely fill the cavities on hydrophilic surfaces and thus deteriorate boiling heat transfer. On hydrophobic surfaces, deposition of nanoparticles led to a biphilic surface, thereby enhancing boiling heat transfer. As the cavity size increased, smaller portion of the cavities was filled with nanoparticles, and nucleation could still occur from the nucleation sites.
•Ferrofluid pool boiling experiments on surfaces with artificial cavities were performed.•The combined effect of external magnetic field and surface modification was investigated.•The effect of magnetic field was more pronounced on surfaces with larger pitch sizes.•Deposited nanoparticles tended to completely fill the cavity on hydrophilic surfaces.•On hydrophobic surfaces, deposition of nanoparticles led to a biphilic surface.
Background
Laparoscopic surgery has several advantages when compared to open surgery, including faster postoperative recovery and lower pain scores. However, for laparoscopy, a pneumoperitoneum is ...required to create workspace between the abdominal wall and intraabdominal organs. Increased intraabdominal pressure may also have negative implications on cardiovascular, pulmonary, and intraabdominal organ functionings. To overcome these negative consequences, several trials have been performed comparing low- versus standard-pressure pneumoperitoneum.
Methods
A systematic review of all randomized controlled clinical trials and observational studies comparing low- versus standard-pressure pneumoperitoneum.
Results and conclusions
Quality assessment showed that the overall quality of evidence was moderate to low. Postoperative pain scores were reduced by the use of low-pressure pneumoperitoneum. With appropriate perioperative measures, the use of low-pressure pneumoperitoneum does not seem to have clinical advantages as compared to standard pressure on cardiac and pulmonary function. Although there are indications that low-pressure pneumoperitoneum is associated with less liver and kidney injury when compared to standard-pressure pneumoperitoneum, this does not seem to have clinical implications for healthy individuals. The influence of low-pressure pneumoperitoneum on adhesion formation, anastomosis healing, tumor metastasis, intraocular and intracerebral pressure, and thromboembolic complications remains uncertain, as no human clinical trials have been performed. The influence of pressure on surgical conditions and safety has not been established to date. In conclusion, the most important benefit of low-pressure pneumoperitoneum is lower postoperative pain scores, supported by a moderate quality of evidence. However, the quality of surgical conditions and safety of the use of low-pressure pneumoperitoneum need to be established, as are the values and preferences of physicians and patients regarding the potential benefits and risks. Therefore, the recommendation to use low-pressure pneumoperitoneum during laparoscopy is weak, and more studies are required.
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