Duration Of Collapse Research Articles

Gap tolerance and molten pool destabilization mechanism in oscillating laser-arc hybrid welding of aluminum alloys

Oscillating laser-arc hybrid welding (O-LAHW) offers significant advantages in enhancing efficiency and mechanical properties. However, in actual production, gap fluctuations can cause instability, limiting its application in large-scale structure manufacturing. In this study, we explored the impact of gap fluctuation on the destabilization of the molten pool in aluminum alloy O-LAHW and identified the maximum gap tolerance for various conditions. High-speed photography revealed that the oscillating molten pool undergoes a transitional state of periodic collapse before complete instability, a behavior distinct from that of a non-oscillating molten pool. We also analyzed the variations in weld geometry prior to destabilization and developed a global force model of the molten pool to identify key geometrical parameters and related driving forces contributing to destabilization. The results show that maintaining a surface tension ratio of over 55 % at the root of the molten pool is crucial for its stability. Additionally, the effects of oscillatory behavior and gap variations on the laser-substrate interaction were explored, revealing the physical mechanisms behind the changes in key geometrical parameters of the melt pool cross-section. The centrifugal effect generated by high-frequency oscillation is identified as a crucial mechanism for extending the duration of periodic collapse compared to non-oscillating molten pools. By discussing the interactions between energy absorption, molten pool shape, and molten pool forces, the study reveals the evolution process of weld destabilization and explains the differences in gap tolerance between oscillating and non-oscillating laser-arc hybrid welding, providing a reference for improving weld stability.

Collapsing molecular clouds with tracer particles – II. Collapse histories

ABSTRACT In order to develop a complete theory of star formation, one essentially needs to know two things: what collapses and how long it takes. This is the second paper in a series, where we query how long a parcel of gas takes to collapse and the process it undergoes. We embed pseudo-Lagrangian tracer particles in simulations of collapsing molecular clouds, identify the particles that end in dense knots, and then examine the collapse history of the gas. We find a nearly universal behaviour of cruise-then-collapse, wherein a core stays at intermediate densities for a significant fraction of its life before finally collapsing. We identify time immediately before each core collapses, $t_{\rm {sing}}$, and examine how it transitions to high density. We find that the time to collapse is uniformly distributed between $0.25 t_{\rm {ff}}$ and the end of the simulation at $\sim\!\! 1 t_{\rm {ff}}$, and that the duration of collapse is universally short, $\Delta t \sim 0.1 t_{\rm {ff}}$, where $t_{\rm {ff}}$ is the free-fall time at the mean density. We describe the collapse in three stages: collection, hardening, and singularity. Collection sweeps low-density gas into moderate density. Hardening brings kinetic and gravitational energies into quasi-equipartition. Singularity is the free-fall collapse, forming an envelope in rough energy balance and central overdensity in $\sim\!\! 0.1 t_{\rm {ff}}$.

Total duration of spontaneous blastocyst collapse during the expansion stage is an independent predictor of euploidy and live birth rates

Research question: Is the total duration of blastocyst spontaneous collapse to re-expansion before biopsy related to ploidy and live birth after single euploid blastocyst transfers?Design: This study conducted a retrospective cohort study of 600 preimplantation genetic testing cycles for aneuploidy (PGT-A) cycles, involving 2203 biopsied blastocysts, at a large reproductive medicine center. Features of blastocyst spontaneous collapse from full to expanded stage, before biopsy, were observed using an embryoscope viewer for embryos cultured in a time-lapse incubator. A total of 568 cycles of frozen blastocyst transfers, either single euploid or mosaic, were performed. Correlations between collapse features and PGT-A outcomes were evaluated, as well as live birth following euploid embryo transfers.Results: Blastocysts with lower morphological quality or delayed development had significantly higher rates of collapse, multiple collapses, and a longer duration of collapse and re-expansion. After controlling for confounders, such as oocyte age, morphological quality, and day of the biopsy, multivariate logistic regression revealed that the total duration of collapses to re-expansion was an independent predictor of lower euploidy rate; the multivariate OR was 0.85 (95% CI: 0.77–0.95, P=0.00). Furthermore, even with euploid embryo transfer, the probability of a live birth decreased as the total duration of collapse to re-expansion increased; the multivariate OR was 0.79 (95% CI: 0.64–0.98, P=0.033).Conclusion: Total duration of blastocyst collapse to re-expansion could be used as a predictor of lower euploidy and the live birth rate. When developing blastocyst algorithms for pregnancy prediction, the duration of blastocyst spontaneous collapse should be included as a significant variable.

Re-expansion Pulmonary Edema

Re-expansion pulmonary edema (RPE) is a rare complication of pleural puncture (thoracentesis) and chest tube insertion. The incidence of RPE is low (1%), but mortality can be up to 20%. The main pathophysiological mechanism is pulmonary edema due to increased permeability and increased hydrostatic pressure in the pulmonary capillaries. Risk factors include duration of lung collapse (>3 to 7 days), size of pneumothorax (>30%), volume of aspirated air or fluid (>1.5 to 3 L), excessive negative intrapleural pressure, diabetes mellitus, and chronic hypoxemia. Prevention includes limiting the volume of aspirated air or fluid (<1.5 L), air or fluid evacuation in a controlled manner, and preventing excessive negative intrapleural pressure. Treatment is supportive care through cardiovascular and respiratory monitoring, oxygen and decubitus positioning.

Study on the effect of bubble number on the collapse of a multi-bubble system near the rigid wall

The mechanism of multi-bubble collapse is one of the key technologies that need to be overcome in the development of large submersibles, which is urgently needed to study and explore. The VOF method is used to study the collapse process of a multi-bubble system near the rigid wall. The bubble collapse process is analyzed under three different bubble numbers and four different initial bubble wall distances. The influence of the number of bubbles and initial bubble wall distance on the bubble collapse process is obtained, and the mechanism of multi-bubble collapsing near the rigid wall is revealed. The results indicate that in a multi-bubble system, as the number of bubbles increases, the duration of bubble collapse increases, the minimum bubble radius decreases, and the maximum central pressure increases. The closer the bubble is to the rigid wall, the longer the duration of bubble collapse, which also lead to fluctuations in the maximum center pressure and maximum interface velocity of a multi-bubble system. The results of this study are expected to provide a theoretical basis and technical support for the design and performance optimization of deep submersible mechanical seals.

HRCT Chest Findings of Re-expansion Pulmonary Edema: A Case Report

Re-expansion pulmonary edema occurs when the lung re-expands after an extended duration of collapse. It is rare with the reported incidence between 0% and 1%. We present a case of a 51-year male who presented with breathlessness, cough and right-sided chest pain. Chest radiograph showed right-sided pneumothorax. After 2 hours of chest tube insertion, the patient developed tachypnea and severe hypoxemia. HRCT chest revealed consolidation, ground glass opacity and smooth interlobular septal thickening in the right lung as well as a small patch of ground glass opacity in the contralateral lung. The serial radiograph showed resolution of consolidation and ground glass opacities.

Bubble cavitation generation near blood vessel walls using amplitude-modulated wave irradiation

We propose an amplitude-modulated pump ultrasound irradiation sequence to generate bubble cavitation for efficient sonoporation. By matching the envelope wavelength of the modulated wave to four times the vessel diameter, we aimed to improve the efficiency of bubble collapse near the vessel wall and extend the duration of collapse during repeated application of the sequence. Using an agarose-based blood vessel phantom, we compared the effects of the amplitude-modulated sequence with those of the normal sinusoidal sequence in which the sound pressure was adjusted so that the acoustic energy in one burst length of each sequence was equal. Compared with the normal irradiation sequence, the amplitude-modulated sequence yielded 2.45- and 1.31-fold greater bubble collapse near the vessel walls proximal and distal, respectively, to the pump ultrasound source, a 1.59-fold longer duration of bubble collapse, and a 1.69-fold larger area of micropores on the channel wall.

O-101 Elucidation of blastocyst collapse and its consequences: a comprehensive artificial intelligence-powered analysis of 1943 embryos from 643 couples

Abstract Study question What are the causes and consequences of blastocyst collapse? Summary answer ∼50% of blastocysts collapsed, especially if they are aneuploid and/or morphologically-poor. Yet, no impact on the live-birth-rate (LBR) per vitrified-warmed euploid single-embryo-transfer (SET) was reported. What is known already Time-lapse-microscopy (TLM) is a powerful tool to describe the peculiar dynamics of preimplantation development. Lately, artificial intelligence (AI) has been also implemented to automatize and standardize such description. Here, we adopted AI to comprehensively portray blastocyst collapse, namely the phenomenon of embryo contraction with an efflux of blastocoel fluid and the detachment of the trophectoderm (TE) from the Zona Pellucida (ZP). Although, the causes of this event are still undetermined, small blastocyst contractions have been reported beneficial for the hatching process, while a full collapse has been associated with lower competence. Study design, size, duration Observational study including 1943 blastocysts from 643 couples cultured in the Embryoscope between January-2013 and December-2020. TE biopsy without day3 ZP drilling and comprehensive-chromosome-testing were performed. The Fairtility® software automatically registered: (i)time of starting-blastulation (tSB), (ii)starting and ending time of each collapse (tSC and tEC), (iii)blastocysts’ areas, (iv)shrinkage% [(area at SC – area at EC)/area at SC)], (v)embryo:ZP ratio at EC (area of the collapsed embryo/area of the ZP), and (vi)time of biopsy (t-biopsy). Participants/materials, setting, methods Blastocyst quality was defined according to Istanbul Consensus (11, excellent; 12-21, good; 22-13-31, average; 33-23-32, poor) and with the Fairtility implantation score (IS) as well, i.e., a continuous variable from 0 to 1 generated by the KID+ software based on the TLM videos of preimplantation development. The main outcome was the LBR per euploid SET adjusted for confounders through logistic regressions. All couple and embryo features were also investigated for their association with blastocyst collapse. Main results and the role of chance 47.3% of the blastocysts collapsed 1- to 9-times (interval between collapses: 4-8hr), and 73% of the couples had ≥1 collapsed blastocyst (1.8±1.1, range:1-8). No couple feature, though, was associated with blastocyst collapse. The longest collapses lasted 1.5±1.1 (0.13-5.1)hr, while the largest shrinkage% and embryo:ZP ratio at EC were 35±14% (10-78%) and 81±9% (33-90%), respectively. In ∼50-60% of collapses a 20-40% blastocyst volume reduction was registered, 40-60% or 20-40% in ∼15-30%, 60-80% in 0-4%. In case of multiple collapses, the first three involved smaller shrinkages. Blastocysts undergoing ≥1 collapse showed similar tSB as not-collapsing blastocysts, but progressively longer tEB and t-biopsy. The earlier the first event, the more the consecutive collapses. Notably, the poorer the morphology, the higher the risk (excellent, good, average, and poor not-collapsing blastocysts were 64%,50%,44% and 37%), number (e.g.,≥4 collapses were 0.4%,2%,4% and 8%) and duration (1.2±1.0,1.4±1.0,1.6±1.1 and 1.9±1.3hr) of blastocyst collapse. Collapsing blastocysts were significantly less euploid than non-collapsing (35% vs 47%; multivariate-OR:0.75,95%CI 0.6-0.92,p<0.01); conversely, their LBR per euploid SET (39% vs 46%) and miscarriage rate per clinical pregnancy (17% vs 11%), were not significantly different (adjusted-OR:1.0,95%CI 0.69-1.48,p=0.96 and adjusted-OR:1.65,95%CI 0.79-3.42,p=0.18, respectively). All data were confirmed also by defining blastocyst quality through the Fairtility IS. Limitations, reasons for caution Gestational and perinatal outcomes were not assessed. Other culture strategies and media shall be assessed for their association with blastocyst collapse. Perhaps, future studies from other groups and with a larger sample size might unveil a significant impact on the clinical outcomes. Wider implications of the findings Collapse is common and delays blastocyst full-expansion. Moreover, poor morphology and aneuploidies involve a higher risk of collapse(s); however, no impact was reported on the clinical outcomes after euploid SET. AI appears to increase the throughput of the analysis, but additional data are required to research the causes of collapse. Trial registration number Not applicable

The frequency of collapse as a predictor of feline blastocyst quality

Domestic cats are frequently used as a research model for felid species that are threatened with extinction. Until now, the development of feline embryos has been evaluated using both classical observation methods and time-lapse monitoring (TLM). Blastocyst collapse observed using time-lapse cinematography is used as a predictor of blastocyst quality and is closely related to implantation potential. The aim of this study was to determine the relationship between the quality of domestic cat blastocysts obtained after in vitro fertilization and the frequency and duration of collapse, and of hatching.There was a significant difference in the average number of collapses and weak contractions between good and poor quality blastocysts. There was no significant difference between hatching and non-hatching blastocysts in terms of blastocyst cavity formation time or average number and duration of collapse.These results showed that the time of cavity formation was not related to blastocyst quality. The number of collapses and the occurrence of hatching were positively related to blastocyst quality, and poor quality blastocysts have, as a consequence, a reduced potential for implantation. TLM plays a significant role in cat embryo evaluation.

Interobserver Agreement of Inferior Vena Cava Ultrasound Collapse Duration and Correlated Outcomes in Children With Dehydration.

Dehydration is a common concern in children presenting to pediatric emergency departments and other acute care settings. Ultrasound (US) of the inferior vena cava (IVC) may be a fast, noninvasive tool to gauge volume status, but its utility is unclear. Our objectives were to determine the interobserver agreement of IVC collapse and collapse duration, then correlate IVC collapse with the outcome of intravenous (IV) versus oral (PO) rehydration. We conducted a prospective study by enrolling patients 0 to 21 years old with emesis requiring ondansetron or diarrhea requiring IV hydration. Clinical operators interpreted US examinations in real time to determine whether the IVC was collapsed. Two blinded reviewers interpreted the US videos to determine IVC collapse and collapse duration. Cohen's kappa(κ) was calculated for reviewer-reviewer and reviewer-operator agreement. Primary outcomes were PO versus IV rehydration, and admitted versus discharged. One hundred twelve patients were enrolled, and 102 had complete data for analysis. The mean age was 7.2 years with 51% female. Twenty-nine patients received IV hydration. The reviewer-operator agreement for IVC collapse was κ = 0.57 (95% confidence interval [CI], 0.38-0.75) and interreviewer agreement was κ = 0.93 (95% CI, 0.83-1.0). The interreviewer agreement for collapse duration was κ = 0.66 (95% CI, 0.51-0.82). All patients with noncollapsed IVCs tolerated PO hydration. The likelihood of receiving IV hydration was correlated with the duration of IVC collapse (P = 0.034). Based on a novel dynamic measure of IVC collapse duration, children with increasing duration of IVC collapse correlated positively with the need for IV rehydration. Noncollapsing IVCs on US were associated with successful PO rehydration without need for IV fluids or emergency department revisits.

Ambipolar diffusion and the molecular abundances in pre-stellar cores

ABSTRACT We investigate differences in the molecular abundances between magnetically super- and subcritical pre-stellar cores, performing three-dimensional non-ideal magnetohydrodynamical (MHD) simulations with varying densities and magnetic field strengths, and post-processing the results with a time-dependent gas–grain chemical code. Most molecular species show significantly more central depletion in subcritical models, due to the longer duration of collapse. However, the directly observable quantities – the molecule to hydrogen column density ratios – are generally too similar for observational data to discriminate between models. The profiles of N2H+ and HCO+ show qualitative differences between supercritical and subcritical models on scales of $0.01 \, {\rm pc}$, which may allow the two cases to be distinguished. However, this requires knowledge of the hydrogen column density, which is not directly measureable, and predicted line intensity profiles from radiative transfer modelling are similar for these molecules. Other commonly observed species, such as HCN and CH3OH, have line intensity profiles that differ more strongly between models, and so are more promising as tracers of the mechanism of cloud collapse.

Profit and equity trade‐offs in the management of small pelagic fisheries: the case of the Japanese sardine fishery*

The management of small pelagic fisheries is difficult due to environmental regime changes that generate multi‐decadal cyclic fluctuations in stock abundance. Lagged management responses to environmental factors can amplify the effects of fishing and may even result in stock collapse. In this paper, we develop an age‐structured bioeconomic model to explore the effectiveness of alternative management approaches for cyclically fluctuating small pelagic fish stocks. The fishery outcomes are evaluated against the overall profit of the fishery and the intertemporal distribution of fishing profits. The model is parameterised for the Japanese sardine fishery, once the largest fishery in Japan, which has experienced a prolonged period of stock collapse over the last 100 years. The results show that the duration of fishery collapse is mostly determined by the extent of cyclic fluctuations in the recruitment of immature sardines, but the effects of the fluctuations on the fishery are heightened by the cumulative impact of fishing. We further show that restricting fishing reduces the fishery’s overall profits, but smooths the intertemporal distribution of profits, resulting in greater intergenerational equity. This income smoothing effect is particularly pronounced when the stock exhibits high levels of cyclic fluctuations.

Light-Responsive Polymer Particles as Force Clamps for the Mechanical Unfolding of Target Molecules

Single-molecule force spectroscopy techniques are powerful tools for investigating the mechanical unfolding of biomolecules. However, they are limited in throughput and require dedicated instrumentation. Here, we report a force-generating particle that can unfold target molecules on-demand. The particle consists of a plasmonic nanorod core encapsulated with a thermoresponsive polymer shell. Optical heating of the nanorod leads to rapid collapse of the polymer, thus transducing light into mechanical work to unfold target molecules. The illumination tunes the duration and degree of particle collapse, thus controlling the lifetime and magnitude of applied forces. Single-molecule fluorescence imaging showed reproducible mechanical unfolding of DNA hairpins. We also demonstrate the triggering of 50 different particles in <1 min, exceeding the speed of conventional atomic force microscopy. The polymer force clamp represents a facile and bottom-up approach to force manipulation.

Mechanics of Collapse of WTC Towers Clarified by Recent Column Buckling Tests of Korol and Sivakumaran

The previously formulated model of the gravity-driven collapse of the twin towers of the World Trade Center (WTC) on September 11, 2011 was shown to match all the existing observations, including the video record of the crush-down motion of the top part of tower during the first few seconds, the seismically recorded duration of collapse, the size distribution of particles caused by impact comminution of concrete floor slabs, the loud booms due to near-sonic lateral ejection velocity of air and dust, and precedence of the crush-down collapse mode before the crush-up. Nevertheless, different degrees of ductility, fracturing and end support flexibility of WTC columns could lead to an equally good match of these observations and remained uncertain, due to lack of test data. Recently, Korol and Sivakumaran reported valuable experiments that allow clarifying this uncertainty. They revealed that, under the simplifying assumptions of rigid end supports and unlimited ductility (or no fracturing) of unheated columns, the energy dissipation of the WTC columns would have been at maximum 3.5-times as large as that calculated by the plastic hinge mechanism normally considered for small-deflection buckling. This increase would still allow close match of all the aforementioned observations except for the first two seconds of the video. The proper conclusion from Korol and Sivakumaran’s tests, based on close matching of the video record, is that the fracturing of unheated columns and the flexibility of their end restraints must have significantly reduced the energy dissipation in columns calculated under the assumptions of no fracture and no end restraint flexibility.

Role of peak current in conversion of patients with ventricular fibrillation

Peak currents are the final arbiter of defibrillation in patients with ventricular fibrillation (VF). However, biphasic defibrillators continue to use energy in joules for electrical conversion in hopes that their impedance compensation properties will address transthoracic impedance (TTI), which must be overcome when a fixed amount of energy is delivered. However, optimal peak currents for conversion of VF remain unclear. We aimed to determine the role of peak current and optimal peak levels for conversion in collapsed VF patients. Adult, non-pregnant patients presenting with non-traumatic VF were included in the study. All defibrillations that occurred were included. Impedance values during defibrillation were used to calculate peak current values. The endpoint was return of spontaneous circulation (ROSC). Of the 197 patients analysed, 105 had ROSC. Characteristics of patients with and without ROSC were comparable. Short duration of collapse < 10 minutes correlated positively with ROSC. Generally, patients with average or high TTI converted at lower peak currents. 25% of patients with high TTI converted at 13.3 ± 2.3 A, 22.7% with average TTI at 18.2 ± 2.5 A and 18.6% with low TTI at 27.0 ± 4.7 A (p = 0.729). Highest peak current conversions were at < 15 A and 15-20 A. Of the 44 patients who achieved first-shock ROSC, 33 (75.0%) received < 20 A peak current vs. > 20 A for the remaining 11 (25%) patients (p = 0.002). For best effect, priming biphasic defibrillators to deliver specific peak currents should be considered.

A multicenter prospective randomized study comparing the efficacy of escalating higher biphasic versus low biphasic energy defibrillations in patients presenting with cardiac arrest in the in-hospital environment.

BackgroundBiphasic defibrillation has been practiced worldwide for >15 years. Yet, consensus does not exist on the best energy levels for optimal outcomes when used in patients with ventricular fibrillation (VF)/pulseless ventricular tachycardia (VT).MethodsThis prospective, randomized, controlled trial of 235 adult cardiac arrest patients with VF/VT was conducted in the emergency and cardiology departments. One group received low-energy (LE) shocks at 150–150–150 J and the other escalating higher-energy (HE) shocks at 200–300–360 J. If return of spontaneous circulation (ROSC) was not achieved by the third shock, LE patients crossed over to the HE arm and HE patients continued at 360 J. Primary end point was ROSC. Secondary end points were 24-hour, 7-day, and 30-day survival.ResultsBoth groups were comparable for age, sex, cardiac risk factors, and duration of collapse and VF/VT. Of the 118 patients randomized to the LE group, 48 crossed over to the HE protocol, 24 for persistent VF, and 24 for recurrent VF. First-shock termination rates for HE and LE patients were 66.67% and 64.41%, respectively (P=0.78, confidence interval: 0.65–1.89). First-shock ROSC rates were 25.64% and 29.66%, respectively (P=0.56, confidence interval: 0.46–1.45). The 24-hour, 7-day, and 30-day survival rates were 85.71%, 74.29%, and 62.86% for first-shock ROSC LE patients and 70.00%, 50.00%, and 46.67% for first-shock ROSC HE patients, respectively. Conversion rates for further shocks at 200 J and 300 J were low, but increased to 38.95% at 360 J.ConclusionFirst-shock termination and ROSC rates were not significantly different between LE and HE biphasic defibrillation for cardiac arrest patients. Patients responded best at 150/200 J and at 360 J energy levels. For patients with VF/pulseless VT, consideration is needed to escalate quickly to HE shocks at 360 J if not successfully defibrillated with 150 or 200 J initially.

Source mechanisms of volcanic tsunamis.

Volcanic tsunamis are generated by a variety of mechanisms, including volcano-tectonic earthquakes, slope instabilities, pyroclastic flows, underwater explosions, shock waves and caldera collapse. In this review, we focus on the lessons that can be learnt from past events and address the influence of parameters such as volume flux of mass flows, explosion energy or duration of caldera collapse on tsunami generation. The diversity of waves in terms of amplitude, period, form, dispersion, etc. poses difficulties for integration and harmonization of sources to be used for numerical models and probabilistic tsunami hazard maps. In many cases, monitoring and warning of volcanic tsunamis remain challenging (further technical and scientific developments being necessary) and must be coupled with policies of population preparedness.

Massive hydrothorax following supracostal percutaneous nephrolithotomy.

Sir, Percutaneous nephrolithotomy (PCNL) is used commonly for the treatment of large renal and upper ureteric calculi. We report a 30-year-old female who developed a massive hydrothorax diagnosed postoperatively following PCNL for left renal calculus. Standard anaesthesia with controlled ventilation was administered. PCNL was performed in the prone position with a left supracostal (between 11th and 12th rib) approach. Multiple attempts were required to reach the superior calyx. Intraoperatively the patient remained haemodynamically stable. The procedure lasted 120 min; blood loss was ≈ 400 mL. Following extubation the patient was comfortable and haemodynamically stable with oxygen saturation (SpO2) 98% on 40% oxygen. After 30 min, the patient complained of breathing difficulty. She was tachypnoeic, with SpO284% (O2 5 L/min). Air entry was absent in left hemithorax, with dullness on percussion. Chest radiograph revealed left hydrothorax [Figure 1a]. An intercostal chest drain with underwater seal was inserted in the left 5th intercostal space. Haemorrhagic fluid (850 mL) was drained. Patient experienced difficulty in breathing following rapid pleural decompression. Continuous positive airway pressure was given by face mask with 100% oxygen for 20 min. Thereafter, she was asymptomatic, SpO2 was 100% and arterial blood gas analysis was normal. Repeat chest radiograph 24 h later showed lung expansion [Figure 1b]. The drain was removed on the 3rd postoperative day. The patient was discharged on the 6th postoperative day.Figure 1: Postoperative chest radiograph showing (a) opacity of left hemithorax and (b) re-expansion of the lung at 24 hAnaesthetic challenges during PCNL include the potential for fluid absorption, dilutional anaemia, hypothermia, blood loss, injury to adjacent organs and pleural space violation.[12] The renal calyceal system can be accessed via a subcostal or supracostal route. The supracostal access (above the 12th or 11th rib) is commonly used as it provides direct access to the upper, middle and lower calyx and the upper ureter.[2] However, this approach can potentially damage the lung and pleura resulting in hydrothorax, pneumothorax or hydropneumothorax.[1] Pleural injury can be avoided by supracostal puncture over the most lateral portion of the 12th rib as this portion of the diaphragm is not covered by a pleural reflection.[3] The intercostal puncture is made in the lower half of the intercostal space to avoid injury to intercostal vessels.[4] The supracostal approach requires coordination with the anaesthesiologist to control ventilation. The needle is passed through the retro-peritoneum and diaphragm during complete exhalation to prevent injury to the lung. The passage of the needle through the renal parenchyma to the collecting system is done during deep inspiration (the kidney gets displaced downwards). An Amplatz sheath is used to maintain low-pressure irrigation that can reduce the risk of pleural effusion and extravasation.[4] Reasons for development of hydrothorax are three-fold: (a) Inadvertent entry into the pleura; (b) inadequate tamponade of the nephrostomy tract combined with inadequate drainage of the kidney after the puncture; and (c) failure to seal the tract with a working sheath during stone removal.[5] Hydrothorax and pneumothorax can be difficult to identify during PCNL. Intraoperatively, a decrease in SpO2 and a significant increase of airway pressure is suggestive of hydrothorax. The diagnosis can be confirmed with a chest radiograph; with the patient in the prone position, fluid can be seen tracking along the lateral borders of the chest cavity and compressing the ipsilateral lung.[3] In the immediate postoperative period, pleural injury presents clinically with poor SpO2, dyspnoea and tachypnoea.[4] A postoperative chest X-ray is mandatory. The treatment of hydrothorax depends on patient symptoms and its extent.[4] Patients with no or mild symptoms and minimal effusion are managed conservatively; those with significant symptoms and large pleural effusion need intercostal drainage. Re-expansion pulmonary oedema, an uncommon complication following drainage of a pneumothorax or pleural effusion, presents clinically as cough, chest discomfort and hypoxemia. Risk factors include young age, long duration of lung collapse and rapid re-expansion. Treatment is largely supportive (oxygen supplementation, noninvasive and invasive ventilation). A high index of suspicion should be maintained when PCNL is performed with a prolonged operating time, multiple tracts and supracostal access. The access puncture should be performed in complete lung deflation and ventilator stand-still in coordination with the anaesthesiologist to minimise the risk of pleural injury. A chest X-ray should be performed promptly in symptomatic postoperative patients to exclude intrathoracic injury. Hydrothorax, haemothorax and/or pneumothorax sustained during PCNL may necessitate chest tube placement.

Reexpansion pulmonary edema: review of pediatric cases

Reexpansion pulmonary edema (RPE) is an increased permeability pulmonary edema that usually occurs in the reexpanded lung after several days of lung collapse. This condition is recognized to occur more frequently in patients under the age of 40years, but there has been no detailed analysis of reported pediatric cases of RPE to date. For this review, PubMed literature searches were performed using the following terms: 're(-)expansion pulmonary (o)edema' AND ('child' OR 'children' OR 'infant' OR 'boy' OR 'girl' OR 'adolescent'). The 22 pediatric cases of RPE identified were included in this review. RPE was reported in almost the entire pediatric age range, and as in adult cases, the severity ranged from subclinical to lethal. No specific treatment for RPE was identified, and treatment was administered according to the clinical features of each patient. Of the 22 reported cases, 10 occurred during the perioperative period, but were not related to any specific surgical procedures or anesthetic techniques, or to the duration of lung collapse. Pediatric anesthesiologists should be aware that pediatric RPE can occur after reexpansion of any collapsed lung and that some invasive therapies can be useful in severe cases.

The risk for re-expansion pulmonary edema following spontaneous pneumothorax

Re-expansion pulmonary edema is an uncommon condition that occurs when a collapsed lung is expanded. The aim of the present study was to investigate the incidence and risk factors associated with re-expansion pulmonary edema which may occur as a complication when carrying out treatment for spontaneous pneumothorax. A total of 462 patients with spontaneous pneumothorax treated with chest tube drainage in inpatient settings at the Nissan Tamagawa Hospital during the 6-year period between January 2007 and December 2012 were retrospectively evaluated. The data were analyzed to identify any clinical differences between the patients with and without re-expansion pulmonary edema. Re-expansion pulmonary edema occurred on 30 (6.5 %) of the 462 patients. The duration of lung collapse in the patients with re-expansion pulmonary edema was longer than that observed in the patients without re-expansion pulmonary edema. (7.7 ± 9.1 and 2.4 ± 4.6 days). This difference was statistically significant (P < 0.0001). The extent of lung collapse in the patients with re-expansion pulmonary edema was more severe than that observed in the patients without re-expansion pulmonary edema. This difference was also statistically significant (P = 0.004). The results suggest that treating spontaneous pneumothorax using chest tube drainage requires careful consideration in view of the relatively high incidence of re-expansion pulmonary edema, especially in cases associated with long periods of lung collapse or large spontaneous pneumothoraxes.