Tunable polarization control with self-assembled arrays of anisotropic plasmonic coaxial nanocavities.

Polarization control with nanostructures having a tunable design and allowing inexpensive large-scale fabrication is important for many nanophotonic applications. For this purpose, we developed and experimentally demonstrated nanostructured plasmonic surfaces based on hexagonal arrays of anisotropic coaxial nanocavities, which can be fabricated by a low-cost self-assembled nanosphere lithography method. Their high polarization sensitivity is achieved by engineering anisotropy of the coaxial nanocavities, while the optical response is enhanced by the excitation of surface plasmon resonances. Particularly, varying the geometrical parameters of the coaxial nanocavities, namely the height and tilt angle of their central core nanoellipsoids, the plasmonic resonance wavelengths as well as the polarization-selective behavior can be individually tuned in the entire visible and near-infrared spectral regions, which makes such nanostructures good candidates for the implementation of polarization-controlled optical switches and polarization-tunable filters. Moreover, the developed nanostructures demonstrate sensitivity up to 1335 nm/RIU in refractive index sensing.

Dual-mode independent detection of pressure and refractive index by miniature grating-coupled surface plasmon sensor.

Multiple parameters need to be monitored to analyze the kinetics of biological progresses. Surface plasmon polariton resonance sensors offer a non-invasive approach to continuously detect the local change of refractive index of molecules with high sensitivity. However, the fabrication of miniaturized, compact, and low-cost sensors is still challenging. In this paper, we propose and demonstrate a grating-coupled SPR sensor platform featuring dual mode operation for simultaneous sensing of pressure and refractive index, which can be fabricated using a highly-efficient low-cost method, allowing large-scale production. Both sensing functionalities are realized by optical means via monitoring the spectral positions of a surface plasmon polariton mode (for refractive index sensing) and Fabry-Perot or metal-insulator-metal modes (for pressure sensing), which are supported by the structure. Simultaneous measurement of refractive index with the sensitivity of 494 nm/RIU and pressure was demonstrated experimentally. The proposed platform is promising for biomonitoring that requires both high refractive index sensitivity and local pressure detection.

Effective switching of an all-solid-state mode-locked laser by a graphene modulator.

Although sophisticated novel saturable absorber materials are available for the development of ultrafast lasers, innovative approaches and devices play an increasingly important role in continuously adjusting mode-locked lasers with electrical gating. In this study, electrically switched operational regimes of an Nd:YVO4 all-solid-state mode-locked laser with a high modulation ratio (from 900 ns to 15 ps) are demonstrated for the first time. The laser can automatically switch multiple operation regimes with the assistance of electrical signals using techniques such as Q-switching, Q-switched mode-locking (QML), and continuous-wave mode-locking (CWML). The device is operated at an ultralow electrical modulation power (0.1 nW) to generate sub 15 ps pulses with a high average output power (as much as 800 mW) from a mode-locked laser operating at 1064 nm. The results verify the reversible switching of the operational regimes from QML to CWML and provide a basis for exploring their applications in electro-optical devices.

Dynamic control of the mode-locked fiber laser using a GO/PS modulator.

This Letter proposes a novel, to the best of our knowledge, transistor-like optical fiber modulator composed of graphene oxide (GO) and polystyrene (PS) microspheres. Unlike previously proposed schemes based on waveguides or cavity enhancement, the proposed method can directly enhance the photoelectric interaction with the PS microspheres to form a light local field. The designed modulator exhibits a distinct optical transmission change (62.8%), with a power consumption of <10 nW. Such low power consumption enables electrically controllable fiber lasers to be switched in various operational regimes, including continuous wave (CW), Q switched mode-locked (QML), and mode-locked (ML). With this all-fiber modulator, the pulse width of the mode-locked signal can be compressed to 12.9 ps, and the corresponding repetition rate is 21.4 MHz.

Relative humidity sensor based on a silver nano-grating made from DVD discs.

A relative humidity sensor based on a silver nano-grating was proposed. By stripping and cleaning commercially available CD and DVD discs, polycarbonate plates with different grating periods are obtained. These plates as templates are coated with a layer of sputtered silver film to form silver nano-gratings, which exhibit refractive index sensing sensitivities of 517 nm/RIU and 742.9 nm/RIU, respectively. The finite-difference time-domain simulation results conform the excited surface plasmon polariton modes and localized surface plasmon modes on the nano-grating. By spin coating a layer of humidity-sensitive porous silica with optimized thickness, the silver nano-grating shows a relative humidity detection sensitivity of 0.23 nm/%RH.

Near-UV luminescence tomography with an aperture-free meta super oscillatory lens for single molecule detection.

Medical physics offers super oscillatory lenses (SOL) to attain subwavelength focusing for efficient image resolution in the detection of a single molecule. In this paper, we propose a negative-indexed permeability-controlled meta SOL, which restores the light concentration via exciting surface plasmon resonance and enhances luminescence at our region of interest, i.e., fluid sample (${S_L}$SL). The meta SOL is aperture-free in comparison with other techniques (zero-mode waveguides and nano antennas) and hence avoids the constraints, which are posed by nano apertures, to insert a small volume of $ S_L $SL into these nano apertures for detection purposes. The meta SOL is a unique combination of gold split rings mounted on silicon dioxide (${{\rm SiO}_2}$SiO2) substrate and operational in the near-ultraviolet (UV) region. We utilized the phenomena of negative index of refraction, and our simulated trails exploit the magnetic (${\mu _r}$µr) response of the meta SOL by analyzing its transmission spectra in the frequency range from 3.53 to 3.57 Peta Hz. We observe the methodical response of the meta SOL with its ample potential to surpass the resolution at a working wavelength of $\lambda ={84.173}\;{\rm nm}$λ=84.173nm, which enhances luminescence by restoring the evanescent UV magnetic field (${B_{\rm UV}}$BUV) at ${S_L}$SL. This technique will offer a new and easy approach to uplift the efficiency of super oscillatory lenses in the near-UV regime to benefit single molecule detection techniques and thus the novelty.

The influence of coronavirus disease 2019 on emergency department visits in Nanjing, China: A multicentre cross-sectional study.

INTRODUCTION: Influenza has been linked to the crowding in emergency departments (ED) across the world. The impact of the Coronavirus Disease 2019 (COVID-19) pandemic on China EDs has been quite different from those during past influenza outbreaks. Our objective was to determine if COVID-19 changed ED visit disease severity during the pandemic. METHODS: This was a retrospective cross sectional study conducted in Nanjing, China. We captured ED visit data from 28 hospitals. We then compared visit numbers from October 2019 to February 2020 for a month-to-month analysis and every February from 2017 to 2020 for a year-to-year analysis. Inter-group chi-square test and time series trend tests were performed to compare visit numbers. The primary outcome was the proportion of severe disease visits in the EDs. RESULTS: Through February 29 th 2020, there were 93 laboratory-confirmed COVID-19 patients in Nanjing, of which 40 cases (43.01%) were first seen in the ED. The total number of ED visits in Nanjing in February 2020, were dramatically decreased (n = 99,949) in compared to January 2020 (n = 313,125) and February 2019 (n = 262,503). Except for poisoning, the severe diseases in EDs all decreased in absolute number, but increased in proportion both in year-to-year and month-to-month analyses. This increase in proportional ED disease severity was greater in higher-level referral hospitals when compared year by year. CONCLUSION: The COVID-19 outbreak has been associated with decreases in ED visits in Nanjing, China, but increases in the proportion of severe ED visits.

Dachengqi decoction alleviates acute lung injury and inhibits inflammatory cytokines production through TLR4/NF-κB signaling pathway in vivo and in vitro.

BACKGROUND AND OBJECTIVES: Sepsis that arises from uncontrolled pulmonary inflammation could induce acute lung injury (ALI), leading to the high death rate. Dachengqi decoction (DCQD) is a common traditional Chinese herbal medicine with strong anti-inflammatory effects. The current study aimed to explore the effect of DCQD on the inflammatory cytokines production, the aquaporin-1 (AQP-1) and AQP-5 protein expression in lipopolysaccharide (LPS)-induced ALI models, and the potential mechanisms underlying its effects. METHODS: Sprague-Dawley rats and HULEC-5a cells were used as study models in the research. To detect related molecules in the study, the real-time polymerase chain reaction analysis, cell counting kit-8 assay, Western blot analysis, and enzyme-linked immunosorbent assay were performed. RESULTS: DCQD could inhibit the expression of LPS-induced inflammatory cytokines, including interleukin-6 (IL-6), IL-8, and tumor necrosis factor-α (TNF-α), in lung tissues and could reduce pulmonary edema by upregulating the expression of AQP-1 and AQP-5 in rats with LPS-induced ALI. Moreover, the results suggested that the toll-like receptor 4 (TLR4)/NF-κB signaling is indispensable for DCQD to increase the expression of AQP-1 and AQP-5 and inhibits the production of IL-6, IL-8, and TNF-α in LPS-induced HULEC-5a cells. CONCLUSION: The results of our study suggested that DCQD suppresses the TLR4/NF-κB signaling pathway, increases the protein expression of AQP-1 and AQP-5, and inhibits the production of inflammatory cytokines, by which it may alleviate the inflammatory reactions in ALI and benefit the treatments.

Vertical flow assays based on core-shell SERS nanotags for multiplex prostate cancer biomarker detection.

Rapid, simultaneous, and sensitive quantification of multiplex prostate biomarkers plays an important role in early diagnosis, especially for obese men and patients. Herein, a surface-enhanced Raman scattering (SERS)-based vertical flow assay (VFA) is presented for simultaneous detection of multiplex prostate cancer biomarkers, such as prostate-specific antigen (PSA), carcinoembryonic antigen (CEA), and alpha-fetoprotein (AFP) on a single test spot. In practice, Raman dyes (RDs) encoded core-shell SERS nanotags instead of conventional gold colloids used in the colorimetric assay are employed in the sensing membrane of SERS based VFAs for multiplex protein detection. Because of the enhanced Raman signal of the core-shell nanostructure and the high surface area to volume ratio (SVR) of the porous sensing membrane, this proposed biosensor shows a wide linear dynamic range (LDR) with detection limits of 0.37, 0.43, and 0.26 pg mL-1 for PSA, CEA, and AFP, respectively, suggesting that this approach can be a good candidate in point of care testing (POCT) for rapid and sensitive biomarker detection and has a huge potential in multiplex analysis and cancer diagnosis.

High Efficiency Light-Emitting Transistor with Vertical Metal-Oxide Heterostructure.

The monolithic integration of light-emission with a standard logic transistor is a much-desired multifunctionality. Here, a high-efficiency light-emitting transistor (LET) employing an inorganic quantum dots (QDs) emitter and a laser-annealed vertical metal-oxide heterostructure is reported. The experimental results show that the peak efficiency and luminance of this QDs LET (QLET) are 11% and 8000 cdm-2 , respectively at a monochromatic emitting light wavelength of 585 nm. As far as it is known, these are among the highest values ever achieved for LETs. More importantly, the QLET exhibits an ultrahigh electron mobility of up to 25 cm2 V-1 S-1 , a lower efficiency roll-off (7% at high 3000 cdm-2 ), and excellent stability with long-duration gate stress switching cycles. Additionally, this approach is compatible with those used in conventional large-area silicon electronic manufacturing and can enable a scalable and cost-effective procedure for future integrated versatile displays and lighting applications.

Integration of tunable two-dimensional nanostructures on a chip by an improved nanosphere lithography method.

By uniform infiltration of a different material into monolayered polystyrene colloidal crystals and by flexibly combining the two materials as etching masks, we demonstrate an improved nanosphere lithography method that possesses the ability to produce a diverse range of tunable nano-patterns in a small area with good reproducibility. The factors that affect the infiltration height and uniformity are characterized and discussed. Annular gap arrays, close-packed ring arrays, and bowl arrays are demonstrated by this method. The geometry size of these nano-patterns can be tuned over the range 10 nm to ∼500 nm with steps of ∼5 nm during the fabrication progress. Formation mechanisms of the close-packed ring arrays are experimentally investigated. Because all the fabrication processes involved in this method are adaptable to sophisticated integrated circuit fabrication techniques, most of the nano-patterns produced by this method could be integrated on thin films, which is desirable for optics integration and array sensing.

Immune-Enhancing Treatment among Acute Necrotizing Pancreatitis Patients with Metabolic Abnormalities: A Post Hoc Analysis of a Randomized Clinical Trial.

Background/Aims: : Metabolic syndrome is common in patients with acute pancreatitis and its components have been reported to be associated with infectious complications. In this post hoc analysis, we aimed to evaluate whether metabolic abnormalities impact the effect of immune-enhancing thymosin alpha-1 (Tα1) therapy in acute necrotizing pancreatitis (ANP) patients. Methods: : All data were obtained from the database for a multicenter randomized clinical trial that evaluated the efficacy of Tα1 in ANP patients. Patients who discontinued the Tα1 treatment prematurely were excluded. The primary outcome was 90-day infected pancreatic necrosis (IPN) after randomization. Three post hoc subgroups were defined based on the presence of hyperglycemia, hypertriglyceridemia, or both at the time of randomization. In each subgroup, the correlation between Tα1 and 90-day IPN was assessed using the Cox proportional-hazards regression model. Multivariable propensity-score methods were used to control potential bias. Results: : Overall, 502 participants were included in this post hoc analysis (248 received Tα1 treatment and 254 received matching placebo treatment). Among them, 271 (54.0%) had hyperglycemia, 371 (73.9%) had hypertriglyceridemia and 229 (45.6%) had both. Tα1 therapy was associated with reduced incidence of IPN among patients with hyperglycemia (18.8% vs 29.7%: hazard ratio, 0.80; 95% confidence interval, 0.37 to 0.97; p=0.03), but not in the other subgroups. Additional multivariate regression models using three propensity-score methods yielded similar results. Conclusions: : Among ANP patients with hyperglycemia, immune-enhancing Tα1 treatment was associated with a reduced risk of IPN (ClinicalTrials.gov, Registry number: NCT02473406).

Early enteral nutrition prevents intra-abdominal hypertension and reduces the severity of severe acute pancreatitis compared with delayed enteral nutrition: a prospective pilot study.

BACKGROUND: To investigate the effects of early enteral nutrition (EEN) on intra-abdominal pressure (IAP) and disease severity in patients with severe acute pancreatitis (SAP). METHODS: Enteral nutrition (EN) was started within 48 h after admission in the EEN group and from the 8th day in the delayed enteral nutrition (DEN) group. The IAP and intra-abdominal hypertension (IAH) incidence were recorded for 2 weeks. The caloric intake and feeding intolerance (FI) incidence were recorded daily after EN was started. The severity markers and clinical outcome variables were also recorded. RESULTS: Sixty patients were enrolled to this study. No difference about IAP was found. The IAH incidence of the EEN group was significantly lower than that of the DEN group from the 9th day (8/30 versus 18/30; P = 0.009) after admission. The FI incidence of the EEN group was higher than that of the DEN group during the initial 3 days of feeding (25/30 versus 12/30; P = 0.001; 22/30 versus 9/30; P = 0.001; 15/30 versus 4/30; P = 0.002). Patients with an IAP <15 mmHg had lower FI incidence than those with an IAP ≥15 mmHg on the 1st day (20/22 versus 17/38; P < 0.001), the 3rd day (11/13 versus 8/47; P < 0.001), and the 7th day (3/5 versus 3/55; P = 0.005) of feeding. The severity markers and clinical outcome variables of the EEN group were significantly improved. CONCLUSIONS: Early enteral nutrition did not increase IAP. In contrast, it might prevent the development of IAH. In addition, EEN might be not appropriate during the initial 3-4 days of SAP onset. Moreover, EN might be of benefit to patients with an IAP <15 mmHg. Early enteral nutrition could improve disease severity and clinical outcome, but did not decrease mortality of SAP.

Modified gastrointestinal failure score for patients with severe acute pancreatitis.

PURPOSE: No consensus has been reached to define gastrointestinal failure (GIF) associated with severe acute pancreatitis (SAP). Reintam and colleagues proposed a scoring system of GIF for critically ill patients, but its suitability for patients with SAP is questionable. The present study evaluates a modified GIF score we developed to assess the GIF of patients with SAP. METHODS: The subjects of this study were 52 patients with SAP treated between September 2010 and July 2011. We recorded the Reintam's GIF score, our modified GIF score, the acute physiology and chronic health evaluation (APACHE) II score, the sequential organ failure assessment (SOFA) score, and other clinical values during the first 3 days after admission. The prognostic value of the modified GIF score, for evaluating the severity and outcomes of SAP, was also assessed. RESULTS: Compared with the Reintam's GIF score, the modified GIF score seemed to be more valuable for predicting hospital mortality (the area under curve, AUC 0.915 vs. 0.850), multiple organ dysfunction syndrome (MODS) (AUC 0.829 vs. 0.766), and pancreatic infection (AUC 0.796 vs. 0.776). Moreover, combining the modified GIF score and the SOFA or APACHEII scores resulted in more accurate prediction of the prognosis of SAP than either score alone. CONCLUSION: The modified GIF score is useful for assessing gastrointestinal system function, which may serve as an early prognostic tool to evaluate the severity and predict the outcomes of SAP.

A 3D Biocompatible Plasmonic Tweezer for Single Cell Manipulation.

Plasmonic tweezers are an emerging research topic because of their low input power and wide operating range from homogeneous particles to complex biological objects. But it is still challenging for plasmonic tweezers to trap or manipulate objects of tens of microns, especially in biological science. This study introduces a new 3D biocompatible plasmonic tweezer for single living cell manipulation in solution. The key design is a tapered tip whose three-layer surface structure consists of nanoprobe, gold nanofilm, and thermosensitive hydrogel, thiolated poly(N-isopropylacrylamide). Incident light excites the surface plasmon polaritons on gold film and generates heat to induce thermally driven phase transition of the thermosensitive hydrogel, which enables reversible binding between functionalized surface and cell membrane and avoids both thermal and mechanical stresses in the meanwhile. The 3D biocompatible plasmonic tweezer realizes selective capture, 3D pathway free transport, and position-controlled release of target cells, and it displays excellent biocompatibility, low energy consumption, and high operational flexibility.

Risk factors and outcome of intra-abdominal hypertension in patients with severe acute pancreatitis.

BACKGROUND: Intra-abdominal hypertension (IAH) is common in patients with severe acute pancreatitis (SAP). The aim of the present study was to investigate the risk factors of IAH in SAP patients and assess the prognosis of SAP combined with IAH. METHODS: To analyze the data from patients with SAP, both univariate and multivariate logistic regression analyses were applied, using 16 indices, including age, gender, Acute Physiology and Chronic Health Evaluation II scores (APACHE II), 24 h fluid balance, hematocrit, serum calcium level, and so on. Clinical prognosis such as mortality, hospital duration, of SAP patients with or without IAH was also compared. RESULTS: First 24 h fluid balance (Odds Ratio [OR], 1.003; 95% Confidence Interval [CI], 1.001-1.006), number of fluid collections (OR, 1.652; 95% CI, 1.023-2.956), and serum calcium level (OR, 0.132; 95% CI, 0.012-0.775) were found to be independent risk factors for IAH in patients with SAP. Moreover, patients with SAP and IAH had significantly longer average length of stay, both in the hospital and in the intensive care unit, higher rates of systemic and local complications, and more invasive treatments. CONCLUSIONS: The significant risk factors for IAH in patients with SAP include 24 h fluid balance (first day), number of fluid collections, and serum calcium level. Additionally, IAH is associated with extremely poor prognosis, evidenced by high rates of mortality, morbidity, and the need for invasive interventions.

Immune enhancement in patients with predicted severe acute necrotising pancreatitis: a multicentre double-blind randomised controlled trial.

PURPOSE: Infected pancreatic necrosis (IPN) is a highly morbid complication of acute necrotising pancreatitis (ANP). Since there is evidence of early-onset immunosuppression in acute pancreatitis, immune enhancement may be a therapeutic option. This trial aimed to evaluate whether early immune-enhancing Thymosin alpha 1 (Tα1) treatment reduces the incidence of IPN in patients with predicted severe ANP. METHODS: We conducted a multicentre, double-blind, randomised, placebo-controlled trial involving ANP patients with an Acute Physiology and Chronic Health Evaluation II (APACHE II) score ≥ 8 and a computed tomography (CT) severity score ≥ 5 admitted within 7 days of the advent of symptoms. Enrolled patients were assigned to receive a subcutaneous injection of Tα1 1.6 mg every 12 h for the first 7 days and 1.6 mg once a day for the subsequent 7 days or matching placebos (normal saline). The primary outcome was the development of IPN during the index admission. RESULTS: A total of 508 patients were randomised, of whom 254 were assigned to receive Tα1 and 254 placebo. The vast majority of the participants required admission to the intensive care unit (ICU) (479/508, 94.3%). During the index admission, 40/254(15.7%) patients in the Tα1 group developed IPN compared with 46/254 patients (18.1%) in the placebo group (difference -2.4% [95% CI - 7.4 to 5.1%]; p = 0.48). The results were similar across four predefined subgroups. There was no difference in other major complications, including new-onset organ failure (10.6% vs. 15%), bleeding (6.3% vs. 3.5%), and gastrointestinal fistula (2% vs. 2.4%). CONCLUSION: The immune-enhancing Tα1 treatment of patients with predicted severe ANP did not reduce the incidence of IPN during the index admission.

[The effect of intra-abdominal hypertension on hemodynamics of acute necrotizing pancreatitis in porcine model].

OBJECTIVE: To assess the effect of intra-abdominal hypertension (IAH) on hemodynamics of severe acute pancreatitis (SAP) in porcine model. METHODS: Following baseline registrations, SAP was induced in 12 animals. The N(2) pneumoperitoneum was used to increase the intra-abdominal pressure to 30 mmHg (1 mmHg = 0.133 kPa) in 6 of 12 SAP animals thereafter and keep constant during the experiment. The investigation period was 12 h. Heart rate, cardiac output (CO), central venous pressure (CVP), mean arterial pressure and pulmonary arterial wedge pressure (PAWP) were continuously measured with the aid of balloon tipped flow-directed catheter and electrocardiography monitor. Oxygen partial pressure of artery (PaO(2)), carbon dioxide partial pressure of artery (PaCO(2)), ScvO(2), base excess (BE), and blood lactic acid (LAC) were measured by acid-base analysis. RESULTS: In the IAH group, CO decreased significantly at 12 h, CVP and PAWP increased significantly at 3 h, 6 h and 12 h compared with SAP group (all P < 0.05). Peak inspiration pressure increased immediately after pneumoperitoneum in the IAH group, to (50.2 ± 3.1) cmH(2)O (1 cmH(2)O = 0.098 kPa) and (49.8 ± 0.9) cmH(2)O at 6 h and 12 h respectively. The pH, PaO(2), ScvO(2) and BE showed a tendency to fall in the IAH group. PaCO(2) and LAC were increased significantly in the IAH group (all P < 0.05). CONCLUSIONS: There were remarkable and relatively irreversible effects on global hemodynamics in response to sustained IAH of 12 h with the underlying condition of SAP. Abdominal decompression is beneficial for patients of SAP with IAH.

[Effect of mechanical ventilation guided by transpulmonary pressure on hemodynamics and oxygen metabolism of porcine model of intra-abdominal hypertension].

OBJECTIVE: To assess the effect of mechanical ventilation (MV) guided by transpulmonary pressure (Ptp) on hemodynamics and oxygen metabolism of porcine model of intra-abdominal hypertension (IAH). METHODS: All 6 pigs were anesthetized and received MV. Volume-assist control was set: tidal volume (V(T)) was 10 ml/kg, respiratory rate (RR) was 16 bpm, inhaled oxygen concentration (FiO(2)) was 0.40 and positive end-expiratory pressure (PEEP) was set at 5 cm H(2)O (1 cm H(2)O=0.098 kPa). Following baseline observations, high intra-abdominal pressure (IAP) with intraperitoneal nitrogen inflation was induced in all 6 pigs. The IAP was increased to 25 mm Hg (1 mm Hg=0.133 kPa). Two hours later, PEEP was adjusted to such a level that Ptp during end-expiratory occlusion remained at a level above 0 cm H(2)O for 2 hours by measuring esophageal pressure, and with the rest parameters of breathing machine remaining constant. During the experimental period, hemodynamic parameters including heart rate (HR), mean arterial pressure (MAP), cardiac output index (CI), central venous pressure (CVP), pulmonary arterial wedge pressure (PAWP), and respiratory mechanics index of peak airway pressure (Ppeak), plateau pressure (Pplat), esophageal pressure (Pes) and static compliance (Cst) were continuously recorded with the aid of Swan-Ganz catheter and electrocardiogram. Oxygen partial pressure of arterial blood (PaO(2) ) and carbon dioxide partial pressure of arterial blood (PaCO(2)) were measured by blood-gas analysis. Systemic oxygen delivery (DO(2) )and systemic oxygen consumption(VO(2) )were calculated according to blood-gas analysis of arterial and central venous blood. RESULTS: No porcine model showed barotrauma and death. Compared with baseline, at 1 hour and 2 hours after induction of IAH in the animals, HR(bpm) increased significantly (134.3±5.8, 127.3±3.3 vs. 117.7±1.5). MAP(mm Hg), CVP (mm Hg) and PAWP (mm Hg) became higher (MAP:120.7±3.8, 117.3±4.8 vs. 100.4±6.6; CVP: 7.3±0.3, 7.6±0.9 vs. 5.6±0.2; PAWP: 14.0±0.6, 14.0±1.0 vs. 12.3±0.3), CI (L×min(-1)×kg(-1)) was lowered (0.150±0.019, 0.137±0.014 vs. 0.179±0.021), Ppeak(cm H(2)O), Pplat (cm H(2)O), Pes (cm H(2)O) were increased significantly (Ppeak: 46.3±2.3, 47.0±3.2 vs. 11.0±1.6; Pplat: 25.7±1.3, 26.0±1.6 vs. 9.0±0.6; Pes: 13.7±0.3, 14.3±0.3 vs. 2.3±0.3), Cst (ml/cm H(2)O), PaO(2) (mm Hg) and DO(2) (ml×min(-1)×kg(-1)) showed significant lowering (Cst: 8.3±0.3, 9.0±0.6 vs. 23.0±1.6; PaO(2) : 142.0±13.2, 140.0±16.0 vs. 166.3±11.3; DO(2) : 19.40±2.90, 19.88 ±4.14 vs. 25.07±6.30, all P<0.05).However, compared to routine ventilation, at 1 hour and 2 hours after PEEP had been adjusted according to measurements of esophageal pressure, PaO(2) , DO(2) and Cst increased significantly (PaO(2) : 161.6±11.9, 164.0±13.6; DO(2) : 21.90±6.21, 21.16±2.78; Cst: 12.0±1.6, 12.7±2.9). CI became lower (0.121±0.013, 0.120±0.012)and Pplat was higher(31.3±3.4, 31.7±3.2, all P<0.05). The lactate (mmol/L) was also decreased significantly (1.60±0.12 vs. 2.70±0.44, 1.67±0.07 vs. 2.27±0.13, both P<0.05). PaCO(2), HR, MAP, CVP and PAWP showed no significant differences compared to IAH pigs ventilated with lower PEEP (all P>0.05). CONCLUSION: There were remarkable effects on oxygen metabolism and Cst and less influence on hemodynamics in response to MV guided by Ptp. The results of this study are in favor of setting Ptp according to measurements of esophageal pressure in pigs with IAH.

[Effect of decompression in different time on hemodynamics and oxygen metabolism of porcine model with severe acute pancreatitis combined intra-abdominal hypertension].

OBJECTIVE: To assess the effect of decompression in different time on systemic hemodynamics and oxygen metabolism in a 24 h lasting porcine model of severe acute pancreatitis (SAP) incorporating intra-abdominal hypertension (IAH). METHODS: Following baseline registrations, SAP was induced in all 18 animals. A N(2) pneumoperitoneum was used to increase the intra-abdominal pressure (IAP) to 25 mmHg (1 mmHg = 0.133 kPa) in 12 of 18 SAP animals. After 6 hours, decompression was applied in 6 of these 12 pigs and the other 6 animals received decompression at 9 h since the induction of IAH. The investigation period was 24 h. Heart rate (HR), cardiac output (CO), central venous pressure (CVP), mean arterial pressure (MAP) and pulmonary arterial wedge pressure (PAWP) were continuously recorded with the aid of Swan-Ganz catheter and electrocardiography monitor; Oxygen partial pressure of artery (PaO(2)), carbon dioxide partial pressure of artery (PaCO(2)) and central venous oxygen saturation (ScvO(2)) were measured by blood-gas analysis. Besides that, systemic oxygen delivery (DO(2)) and systemic oxygen consumption (VO(2)) were calculated according to blood-gas analysis in arterial and central venous blood. RESULTS: After decompression, HR, CO, MAP, CVP, PAWP, PaO(2) and DO(2) showed no significant differences in the 6 h group when compared to SAP pigs. In the 9 h group, however, CO decreased significantly and HR, CVP, PAWP increased significantly after decompression than SAP only animals (all P < 0.05). PaO(2), ScvO(2) and DO(2) showed lower after 3 h of decompression compared with another two groups. VO(2) increased higher in IAH groups during 6 h of experiment than SAP pigs (all P < 0.05). Then VO(2) showed a trend to fall and no differences in three groups. CONCLUSIONS: There are remarkable and relatively irreversible effects on global hemodynamics and oxygen metabolism in response to the decompression in different time after sustained IAH with the underlying condition of SAP. The results of this study are in favor of a decompression in patients of SAP with IAH in early time.