Investigating stronger tolerant network against cascading failures in focusing on changing degree distributions.

Many real-world networks with Scale-Free structure are significantly vulnerable against both intentional attacks and catastrophic cascading failures. On the other hand, it has been shown that networks with narrower degree distributions have strong robustness of connectivity by enhancing loops. This paper numerically reveals that such networks are also tolerant against cascading failures. Our findings will be useful in designing stronger tolerant network infrastructures.

3D transesophageal echocardiographic visualization of the pulmonary artery catheter through the tricuspid valve and their position relative to the tricuspid valve leaflets.

BACKGROUND: The tricuspid valve is an atrioventricular valve consisting of three lobes. We used the 3D transesophageal echocardiography to visualize position of the pulmonary artery catheter at the tricuspid valve annulus and examined where the catheter passed through at the level of the tricuspid annulus. METHODS: In this prospective and observational study, we monitored the pressure wave on patients undergoing cardiac surgery with the catheter placement by monitoring the pressure waveform for 8 months. We measured the time required for the catheter to pass through the tricuspid and pulmonary valves, respectively. We acquired the 3D image of the tricuspid valve by transesophageal echocardiography and determined the position of the pulmonary artery catheter at the level of the tricuspid annulus. The data were analyzed by Kruskal-Wallis test followed by Mann-Whitney test with Holm multiple comparisons. P < 0.05 was considered significant. RESULTS: Of the 116 cases, the pulmonary artery catheter passed through the tricuspid valve between antero-posterior leaflets in 78 cases (67.2 %), between septal-posterior leaflets in 25 cases (21.6 %), and between antero-septal leaflets in 2 cases (1.7 %) and the center in 11 cases (9.5 %), respectively. The time required for the catheter to pass through the pulmonary valves was significantly different among the catheter positions at the level of the tricuspid annulus. CONCLUSION: The pulmonary artery catheter location at the level of the tricuspid annulus can be identified using 3D transesophageal echocardiography. The location of the catheter significantly affects the pulmonary artery catheter placement time.

Anti-modularization for both high robustness and efficiency including the optimal case.

Although robustness of connectivity and modular structures in networks have been attracted much attentions in complex networks, most researches have focused on those two features in Erdos-Renyi random graphs and Scale-Free networks whose degree distributions follow Poisson and power-law, respectively. This paper investigates the effect of modularity on robustness in a modular d-regular graphs. Our results reveal that high modularity reduces the robustness even from the optimal robustness of a random d-regular graph in the pure effect of degree distributions. Moreover, we find that a low modular d-regular graph exhibits small-world property that average path length is O(logN). These results indicate that low modularity on modular structures leads to coexistence of both high robustness and efficiency of paths.

Selective estrogen receptor modulators and deep venous thrombosis after an emergent operation in senior women.

BACKGROUND: Selective estrogen receptor modulators (SERMs), clinically applied to osteoporosis, may have potential risk of deep venous thrombosis (DVT) and discontinuation of SERMs may be required before surgery. However, we cannot discontinue SERMs for a certain duration, when patients undergo an emergent operation. CASE PRESENTATION: We reported two aged patients undergoing an emergent orthopedic surgery for lower extremities while taking SERMs for osteoporosis before the operation. DVT was newly developed in one patient and worsened in the other patient after the operation. We found eight aged patients underwent the same operation while taking SERMs for recent 3 years, including the two cases and DVT did not occur in the other six patients. Thus, the incidence of DVT in our patient population was 25%. CONCLUSION: We showed that DVT developed or worsened after operation in two patients taking SERMs before operation. Ultrasound examination after operation may be recommended in these population. (149 words).

Total arch and descending thoracic aortic replacement for massive hemoptysis requiring CPR caused by intrapulmonary penetration of chronic dissecting aortic aneurysm: a case report.

BACKGROUND: Intrapulmonary penetration of the thoracic aorta is a rare, life-threatening complication of a chronic dissecting aortic aneurysm. It causes massive hemoptysis requiring prompt intervention to prevent fatal airway bleeding. A surgical approach that enables diverse surgical maneuvers and intraoperative organ protection is crucial. CASE PRESENTATION: A 62-year-old man, who underwent graft replacement of the ascending aorta for an acute type A aortic dissection 20 months before, developed massive hemoptysis and cardiac arrest. The hemoptysis was secondary to an aortopulmonary fistula from a rapidly expanding dissecting aortic aneurysm. However, a successful return of spontaneous circulation was achieved with cardiopulmonary resuscitation, including establishment of veno-arterial extracorporeal membrane oxygenation. The patient successfully underwent a total arch and descending thoracic aortic replacement. This was achieved by a median sternotomy combined with a left thoracotomy using a straight incision with a rib-cross (SIRC) approach. The patient was uneventfully discharged and remained well for the following 2 years. CONCLUSIONS: When performing a surgical graft replacement for an aortopulmonary fistula with a thoracic aortic aneurysm, the surgical approach chosen is critical. A surgical procedure using a median sternotomy combined with a left thoracotomy and a SIRC approach can be an effective therapeutic option.

Correction: Hayashi et al. More Tolerant Reconstructed Networks Using Self-Healing against Attacks in Saving Resource. Entropy 2021, 23, 102.

The authors wish to make the following correction to this paper [...].

Adding links on minimum degree and longest distance strategies for improving network robustness and efficiency.

Many real-world networks characterized by power-law degree distributions are extremely vulnerable against malicious attacks. Therefore, it is important to obtain effective methods for strengthening the robustness of the existing networks. Previous studies have been discussed some link addition methods for improving the robustness. In particular, two effective strategies for selecting nodes to add links have been proposed: the minimum degree and longest distance strategies. However, it is unclear whether the effects of these strategies on the robustness are independent or not. In this paper, we investigate the contributions of these strategies to improving the robustness by adding links in distinguishing the effects of degrees and distances as much as possible. Through numerical simulation, we find that the robustness is effectively improved by adding links on the minimum degree strategy for both synthetic trees and real networks. As an exception, only when the number of added links is small, the longest distance strategy is the best. Conversely, the robustness is only slightly improved by adding links on the shortest distance strategy in many cases, even combined with the minimum degree strategy. Therefore, enhancing global loops is essential for improving the robustness rather than local loops.

Practical counting of substitutive paths on a planar infrastructure network.

When there are many non-intersecting paths between two vertices on a network, the connectivity is fault-tolerant. Because of no common vertices on these paths, they can be emergently used in avoiding destroyed parts on the usual paths by any disasters or attacks. It gives a tolerance index whether the combination of non-intersecting paths is many or few. However, to enumerate such paths is an intractable combinatorial problem, no practical algorithm has been known. On the other hand, many socio-technological infrastructure networks are embedded on the surface of Earth. Thus, as an approximate solution, we extendedly apply the counting method based on a path matrix with our proposed mapping to directed acyclic graphs from a planar network according to each pair of source and terminal vertices. The tendency of many or few combinations of the paths is clearly investigated through computer simulations for realistic networks. This approach will be useful for evaluating the existence of substitutive paths to improve the tolerance in risk management.

Postoperative delirium does not affect cardiopulmonary exercise testing in aged patients undergoing cardiac valve surgery.

BACKGROUND: The effect of delirium on cardiopulmonary exercise testing (CPX) is unknown. This retrospective study was to examine the effect of delirium on CPX at discharge in aged patients undergoing cardiac surgery. METHODS: This study included seventy patients aged 70 or older undergoing cardiac valve surgery, who entered our ICU and were discharged from our hospital between June 2016 and July 2018. All patients received active exercise by our rehabilitation team from the first postoperative day and were performed a CPX on a cycle ergometer before discharge. The anaerobic threshold oxygen uptake and the slope of the relationship between carbon dioxide output and minute ventilation were examined. We obtained the patient's data, including patient's characteristics, cardiac function, anesthesia data, laboratory data, ICU data, and length of ICU and hospital stay. Data were analyzed by unpaired t test or Fisher's exact test. P < 0.05 was considered statistically significant. RESULTS: Of the 70 patients, 21 patients experienced delirium during ICU stay. The delirium group needed longer administration of sedatives and longer ICU stay and showed higher CRP value and lower renal function but similar cardiopulmonary function before discharge from our hospital compared with the non-delirium group. CONCLUSIONS: Patients with a history of delirium during ICU showed higher CRP value and lower renal function before discharge, but the CPX values at discharge were not significantly affected by delirium.

Two cases of hemodynamic improvement by modulation of atrioventricular delay in cardiac operations.

BACKGROUND: Symptomatic sick sinus syndrome is one of the indications for pacemaker implantation, and we have to consider to program the pacemaker to an asynchronous pacing mode during an operation. CASE PRESENTATION: We reported two cases with a pacemaker implanted for sick sinus syndrome undergoing cardiac operation. We changed programming of the pacemaker to an asynchronous pacing mode (DOO) and modulated the programmed atrioventricular delay to avoid ventricular pacing, resulting in better hemodynamic condition. Although we observed premature ventricular contraction, no lethal arrhythmias induced by the R-on-T phenomenon were noted. CONCLUSION: Programming of the pacemaker to an asynchronous pacing mode and modulation of the programmed atrioventricular delay to avoid ventricular pacing may be an option for pacemaker management during an operation.

Anesthetic management of a patient with severe aortic regurgitation undergoing reoperation for ascending aorta false aneurysm using hypothermia: prevention of ventricular fibrillation by nifekalant.

BACKGROUND: To prevent cardiac collapse and to protect cerebral function, hypothermic cardiopulmonary bypass is established before resternotomy. However, ventricular fibrillation under hypothermia facilitates left ventricular distension, which causes irreversible myocardial damage when the patient has aortic regurgitation. We report a case of successful management in preventing ventricular fibrillation under hypothermia by using nifekalant. CASE PRESENTATION: A 56-year-old male, who had been performed a David operation, was scheduled for a Bentall operation for a pseudo aortic aneurysm with severe aortic regurgitation. After inducing anesthesia, we administered intravenous nifekalant and a vent tube was inserted into the left ventricle under one-lung ventilation. Extracorporeal circulation was established and resternotomy started after cooling to 27 °C. Although severe bradycardia and QT prolongation were observed, ventricular fibrillation did not occur until aortic cross-clamping. CONCLUSION: Combining maintaining cerebral perfusion and avoiding left ventricle distension during hypothermia was successfully managed with nifekalant in our redo cardiac patient with aortic regurgitation.

More Tolerant Reconstructed Networks Using Self-Healing against Attacks in Saving Resource.

Complex network infrastructure systems for power supply, communication, and transportation support our economic and social activities; however, they are extremely vulnerable to frequently increasing large disasters or attacks. Thus, the reconstruction of a damaged network is more advisable than an empirically performed recovery of the original vulnerable one. To reconstruct a sustainable network, we focus on enhancing loops so that they are not trees, which is made possible by node removal. Although this optimization corresponds with an intractable combinatorial problem, we propose self-healing methods based on enhancing loops when applying an approximate calculation inspired by statistical physics. We show that both higher robustness and efficiency are obtained in our proposed methods by saving the resources of links and ports when compared to ones in conventional healing methods. Moreover, the reconstructed network can become more tolerant than the original when some damaged links are reusable or compensated for as an investment of resource. These results present the potential of network reconstruction using self-healing with adaptive capacity in terms of resilience.

Analysis of difficulty in placement of pulmonary artery catheter through the left internal jugular vein.

PURPOSE: The left internal jugular vein may be an alternative route for the placement of a pulmonary artery catheter when the right jugular vein is not available. Although the placement through the left internal jugular vein is expected to be more difficult, little has been written regarding difficulties in achieving proper placement of the catheter through the left internal jugular vein. METHODS: This prospective and observational study includes patients undergoing cardiac surgery with the catheter placement by monitoring the pressure waveform for 2 years. We measured the time required for the catheter to pass through the tricuspid and pulmonary valves, respectively. The data were analyzed by Mann-Whitney. P < 0.05 was considered significant. RESULTS: The catheter placement through the right and left internal jugular vein was done in 285 (group R) and 10 patients (group L), respectively. The time duration through the tricuspid valve in group L was significantly longer than that in group P (8 [5-14] s vs 70 [19.8-138] s, median [range], P < 0.01), whereas the time duration through the pulmonary valve was comparable between the two groups (15 [10-27.75] s vs 15 [10.25-19] s, median [range], P = 0.62). CONCLUSION: These results indicate that the difficulty in the catheter placement through the left jugular vein may be to pass through the tricuspid valve, not the pulmonary valve.

An analysis of factors influencing pulmonary artery catheter passage through the tricuspid and pulmonary valves.

PURPOSE: A pulmonary artery catheter (PAC) has to pass the tricuspid and pulmonary valves for its proper placement. Although several factors were reported to hinder the placement, there have been no reports to identify the factors that prolong the individual time for passing through each valve. METHOD: We individually measured the time required for a PAC to pass through the tricuspid and pulmonary valves. We examined the effect of the following factors on those times: the patient's age, sex, height, weight, cardiothoracic ratio, tricuspid regurgitation, left ventricular ejection fraction, and the diameters of the sinus of Valsalva and of the sinotubular junction divided by the body surface area which represent the diameter of the aorta. Data were analyzed by multiple linear regression analysis after univariate analysis. RESULTS: The placement of a PAC was successful in all of 100 patients. The time required to pass through the pulmonary valve was significantly longer than that through the tricuspid valve (15 [10-28] s vs 9 [5-16] s, median [range], P < 0.01). The incidence of ventricular arrhythmias during passage through the pulmonary valve was significantly higher than that through the tricuspid valve (17% vs 0%, P < 0.01). Tricuspid regurgitation and the diameter of sinotubular junction had a significant positive association with the time required to advance a PAC through the pulmonary valve, although there was no significant factors that increased the time required to advance a PAC through the tricuspid valve. CONCLUSION: The time required to advance a PAC through the pulmonary valve is much longer than that to pass through the tricuspid valve. The diameter of aortic root and tricuspid regurgitation are significant factors that increased the time required to advance a PAC through the pulmonary valve.

An analysis of prior experience influencing quality of pulmonary artery catheter placement in residents.

Background: Prior experience may be important for successful placement of a pulmonary artery catheter (PAC). However, there is no report about the minimum number of the placement to reach acceptable technique for the catheter placement during residency. Aims: This study was designed to examine quality of the catheter placement and to assess the effect of prior experience. Setting and Design: Prospective, observational, cohort study. Methods: This study included eight residents and one experienced staff in our hospital. We prospectively examined the performance of placement of a PAC in eight residents for the first 2 months of their training period and one staff for previous 2 years. We examined the time required for the catheter placement and probability of ventricular arrhythmias during the placement. Each resident and the staff reported approximate number of past experience of the catheter placement according to the self-statement. In addition, we continued to examine the placement of a PAC in one resident with zero experience to show his improvement. Statistical Analysis: Statistical analysis was performed by Kruskal-Wallis test, Mann-Whitney test, or Fisher's exact test as appropriate and Benjamini and Hochberg method was used for multiple comparisons. Results: The catheter placement time and probability of the ventricular arrhythmias of two residents with zero experience of the placement were significantly larger than those of the staff. On the other hand, the placement quality of the other residents who experienced at least 20 PAC placements was not significantly different from that of the staff. The placement quality of one resident with zero experience became comparable with that of the staff after 20 placements. Conclusion: Our data suggested that about 20 catheter placements may be required to reach acceptable technical level for the PAC placement.

Responsiveness of lumbosacral superficial dorsal horn neurons during the voiding reflex and functional loss of spinal urethral-responsive neurons in streptozotocin-induced diabetic rats.

AIMS: Sensory information from the lower urinary tract (LUT) is conveyed to the spinal cord to trigger and co-ordinate micturition. However, it is not fully understood how spinal dorsal horn neurons are excited during the voiding reflex. In this study, we developed an in vivo technique allowing recording of superficial dorsal horn (SDH) neurons concurrent with intravesical pressure (IVP) during the micturition cycle in both normal and diabetic rats. METHODS: Lumbosacral dorsal horn neuronal activity and IVP were recorded from urethane-anesthetized naive and streptozotocin (STZ)-induced diabetic rats. Saline was continuously perfused into the urinary bladder through a cannula to induce micturition. RESULTS: We classified SDH neurons into bladder- and urethral-responsive neurons, based on their responsiveness during the voiding reflex. Bladder-responsive SDH neurons responded to the rapid increase in IVP at the start of voiding. In contrast, urethral-responsive SDH neuronal firing increased at the peak IVP and their firing lasted during the voiding phase (the high-frequency oscillations). Urethral-responsive SDH neurons were more sensitive to capsaicin, received C afferent fiber inputs, and were rarely detected in STZ-diabetes rats. Administration of a cyclohexenoic long-chain fatty alcohol (TAC-302), which is reported to promote neurite outgrowth of peripheral nerves in STZ-diabetic rats, prevented the functional loss of spinal urethral response. CONCLUSIONS: Sensory information from the bladder and urethra is conveyed separately to different groups of SDH neurons. Functional loss of spinal urethral sensory information through unmyelinated C afferent fibers may contribute to diabetic bladder dysfunction.

Author Correction: Onion-like networks are both robust and resilient.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Onion-like networks are both robust and resilient.

Tolerant connectivity and flow transmission within capacity are crucial functions as network. However, the threats to malicious attacks based on intelligent node selections and rapid breakdown by cascading overload failures increase more and more with large blackout or congestion in our contemporary networking systems and societies. It has been recently suggested that interwoven loops protect the network functions from such damages, but it is a computationally intractable combinatorial problem to maximize a set of necessary nodes for loops in order to improve the robustness. We propose a new method by enhancing loops in the incremental growth for constructing onion-like networks with positive degree-degree correlations, whose topological structure has the optimal tolerance of connectivity against attacks in the state-of-the-art. Moreover, we find out that onion-like networks acquire adaptive capacity in resilience by a change of routing policy for flow control to absorb cascading overload failures triggered by a single attack and simultaneous multi-attacks. The inhibitory effect is stronger than that in scale-free networks found in many real systems.

Dilated aortic root influences pulmonary artery catheter placement in anesthetized patients.

PURPOSE: The placement of a pulmonary artery catheter sometimes needs long time by observing the pressure wave, and several factors have been reported to hinder the placement. In the present study, we examined whether enlargement of the aortic root is associated with longer time for the placement. METHOD: We examined the time required for the catheter placement. The catheter placement time was defined as the duration of time required for the catheter to float from the CVP position to the pulmonary artery. The catheter placement was performed by one experienced physician. We examined the following factors on the catheter placement time: the patient's age, height, weight, cardiothoracic ratio, tricuspid regurgitation, ejection fraction and the diameter of aortic annulus, sinus of Valsalva, sinotubular junction, and proximal ascending aorta. These diameter values were divided by body surface area (BSA) to equalize among different physical sizes. The data were analyzed by multiple linear regression analysis after univariate analysis. RESULTS: The univariate analysis showed that ejection fraction and aortic annulus/BSA, sinus of Valsalva/BSA, and sinotubular junction/BSA correlated with the catheter placement time (P = 0.079, 0.030, 0.029, and 0.025, respectively). Since the three aortic root values correlated with each other, we chose the sinotubular junction/BSA for the following multivariate analysis, because of the highest P value. The multivariate analysis showed that sinotubular junction/BSA had a significant positive association with the placement time (P = 0.048). CONCLUSION: The present study showed that enlargement of the aortic root is associated with long placement time of the catheter.