Background Epinephrine infiltration of the nasal mucosa causes hypotension during functional endoscopic sinus surgery （FESS） under general anesthesia. A prospective randomized-controlled study was designed to determ...Background Epinephrine infiltration of the nasal mucosa causes hypotension during functional endoscopic sinus surgery （FESS） under general anesthesia. A prospective randomized-controlled study was designed to determine whether relatively light general anesthesia is superior to fluid expansion in reducing epinephrine-induced hypotension during FESS. Methods Ninety patients undergoing elective FESS under general anesthesia were randomly assigned to three groups with 30 patients in each. Each patient received local infiltration with adrenaline-containing （5 μg/ml） lidocaine （1%, 4 ml） under different conditions. For Group I, anesthesia was maintained with propofol 2 μg/ml and rimifentanil 2 ng/ml by TCI. Group Ⅱ （control group） and Group Ⅲ received propofol 4 μg/ml and rimifentanil 4 ng/ml, respectively. In Groups I and II, fluid expansion was performed with hetastarch 5 ml/kg within 20 minutes; hetastarch 10 ml/kg was used in Group Ⅲ. Mean arterial pressure （MAP） and heart rate （HR） were recorded at 30-second-intervals for 5 minutes after the beginning of local infiltration. Simultaneously, the lowest and the highest MAP were recorded to calculate the mean maximum increase or decrease percent in MAP for all patients in each group. Data analysis was performed by χ^2 test, one-way analysis of variance, or one-way analysis of covariance. Results Hemodynamic changes, particularly a decrease in MAP accompanied by an increase in HR at 1.5 minutes （P〈0.05）, were observed in all groups. The mean maximum decrease in MAP below baseline was 14% in Group Ⅰ, 24% in Group Ⅲ and 26% in Group Ⅱ. There were statistically significant differences between Group Ⅰ and Groups Ⅱ and Ⅲ （P〈0.05）. The mean maximum increase in MAP above baseline was 9% in Group Ⅰ, 6% in Group Ⅲ and 2% in Group Ⅱ. Conclusion Relatively light general anesthesia can reduce the severity of epinephrine-induced hypotension more effectively than fluid expansion during FESS under general anesthesia.展开更多
The supercritical fluid crystallization technique is a novel technology for preparing ultrafine particles. This paper introduced the concept and features of the technique with an emphasis on three kinds of supercritic...The supercritical fluid crystallization technique is a novel technology for preparing ultrafine particles. This paper introduced the concept and features of the technique with an emphasis on three kinds of supercritical fluid crystallization techniques, i.e. rapid expansion of supercritical solutions, supercritical fluid anti-solvent and particles from gas saturated solutions Some questions and the prospect of this technique were also discussed.展开更多
Stress sensitivity is a key factor affecting the productivity of single wells in low permeability gas reservoirs. A well test model for heterogeneous composite gas reservoirs under the influence of stress-sensitive ef...Stress sensitivity is a key factor affecting the productivity of single wells in low permeability gas reservoirs. A well test model for heterogeneous composite gas reservoirs under the influence of stress-sensitive effects was established. Based on the theoretical model, the well test was designed by gradually increasing the pressure difference. The relationship between abnormal high pressure and reservoir stress sensitivity was analyzed. Theoretical research shows that stress sensitivity will cause permeability damage during the production process, and the pressure drop test curve shows that the physical properties of the reservoir have gradually deteriorated. The pressure recovery test curve shows that the physical properties of the reservoir are getting better. Field practice shows that stress sensitivity is related to the formation of abnormally high pressure in the formation without considering the micro-cracks in the formation. Stress-sensitive reservoirs are generally unbalanced and compacted due to overpressure, for fluid expansion/conduction overpressure in Ledong Area. For these reservoirs, there is almost no stress sensitivity. The research results have significance for guiding the design and data interpretation of stress-sensitive reservoir.展开更多
Much progress in the studies on overpressuring mechanisms has been made during the past one to two decades.(1)The causes of overpressure are divided into five categories,namely,disequilibrium compaction,fluid expansio...Much progress in the studies on overpressuring mechanisms has been made during the past one to two decades.(1)The causes of overpressure are divided into five categories,namely,disequilibrium compaction,fluid expansion,diagenesis,tectonic compression and pressure transfer.The fluid expansion involves hydrocarbon generation,oil cracking to gas and hydrothermal expansion.The diagenesis includes smectite-to-illite transformation.(2)Six methods for identifying overpressure origin are proposed,including log curves combination analysis,Bowers method(loading-unloading diagram),velocitydensity crossplotting,correlation of porosities,pressure calculation and correlation,and comprehensive analyses.(3)With more and more application of empirical methods in the study of overpressure formation,almost all of the overpressure cases that are traditionally thought to be caused by disequilibrium compaction are denied totally or partly.Instead,the hydrocarbon generation is demonstrated to be the most significant mechanism for overpressure formation;the clay diagenesis(especially the smectiteillite transformation)as well as tectonic compression and pressure transfer are also important for overpressure formation.In addition,the overpressure formation in many basins is thought to be influenced by the combination of two or more overpressuring mechanisms.(4)Causes of overpressuring differ in lithology;for mudstones,the overpressure formation in source rocks is usually different from that of non-source rocks,the former of which is frequently related to hydrocarbon generation and sometimes also affected by diagenesis,while the later of which is commonly related to disequilibrium compaction,diagenesis and pressure transfer;for permeable rocks such as sandstones,overpressure is mainly caused by pressure transfer.(5)Because organic matter has an obvious influence on logging parameters such as density and acoustic velocity,an appropriate correction on the content of organic matter is needed when these logging data are used to analyze overpressure formation in organic-rich mudstones.It has been revealed that the cause of overpressuring based on the corrected log data can be quite different from that without correction.展开更多
文摘Background Epinephrine infiltration of the nasal mucosa causes hypotension during functional endoscopic sinus surgery （FESS） under general anesthesia. A prospective randomized-controlled study was designed to determine whether relatively light general anesthesia is superior to fluid expansion in reducing epinephrine-induced hypotension during FESS. Methods Ninety patients undergoing elective FESS under general anesthesia were randomly assigned to three groups with 30 patients in each. Each patient received local infiltration with adrenaline-containing （5 μg/ml） lidocaine （1%, 4 ml） under different conditions. For Group I, anesthesia was maintained with propofol 2 μg/ml and rimifentanil 2 ng/ml by TCI. Group Ⅱ （control group） and Group Ⅲ received propofol 4 μg/ml and rimifentanil 4 ng/ml, respectively. In Groups I and II, fluid expansion was performed with hetastarch 5 ml/kg within 20 minutes; hetastarch 10 ml/kg was used in Group Ⅲ. Mean arterial pressure （MAP） and heart rate （HR） were recorded at 30-second-intervals for 5 minutes after the beginning of local infiltration. Simultaneously, the lowest and the highest MAP were recorded to calculate the mean maximum increase or decrease percent in MAP for all patients in each group. Data analysis was performed by χ^2 test, one-way analysis of variance, or one-way analysis of covariance. Results Hemodynamic changes, particularly a decrease in MAP accompanied by an increase in HR at 1.5 minutes （P〈0.05）, were observed in all groups. The mean maximum decrease in MAP below baseline was 14% in Group Ⅰ, 24% in Group Ⅲ and 26% in Group Ⅱ. There were statistically significant differences between Group Ⅰ and Groups Ⅱ and Ⅲ （P〈0.05）. The mean maximum increase in MAP above baseline was 9% in Group Ⅰ, 6% in Group Ⅲ and 2% in Group Ⅱ. Conclusion Relatively light general anesthesia can reduce the severity of epinephrine-induced hypotension more effectively than fluid expansion during FESS under general anesthesia.
文摘The supercritical fluid crystallization technique is a novel technology for preparing ultrafine particles. This paper introduced the concept and features of the technique with an emphasis on three kinds of supercritical fluid crystallization techniques, i.e. rapid expansion of supercritical solutions, supercritical fluid anti-solvent and particles from gas saturated solutions Some questions and the prospect of this technique were also discussed.
文摘Stress sensitivity is a key factor affecting the productivity of single wells in low permeability gas reservoirs. A well test model for heterogeneous composite gas reservoirs under the influence of stress-sensitive effects was established. Based on the theoretical model, the well test was designed by gradually increasing the pressure difference. The relationship between abnormal high pressure and reservoir stress sensitivity was analyzed. Theoretical research shows that stress sensitivity will cause permeability damage during the production process, and the pressure drop test curve shows that the physical properties of the reservoir have gradually deteriorated. The pressure recovery test curve shows that the physical properties of the reservoir are getting better. Field practice shows that stress sensitivity is related to the formation of abnormally high pressure in the formation without considering the micro-cracks in the formation. Stress-sensitive reservoirs are generally unbalanced and compacted due to overpressure, for fluid expansion/conduction overpressure in Ledong Area. For these reservoirs, there is almost no stress sensitivity. The research results have significance for guiding the design and data interpretation of stress-sensitive reservoir.
基金The work is supported by the National Science and Technology Major Project of China(No.2016ZX05044,2011ZX05007-004)the National Natural Science Foundation of China(No.41502132).
文摘Much progress in the studies on overpressuring mechanisms has been made during the past one to two decades.(1)The causes of overpressure are divided into five categories,namely,disequilibrium compaction,fluid expansion,diagenesis,tectonic compression and pressure transfer.The fluid expansion involves hydrocarbon generation,oil cracking to gas and hydrothermal expansion.The diagenesis includes smectite-to-illite transformation.(2)Six methods for identifying overpressure origin are proposed,including log curves combination analysis,Bowers method(loading-unloading diagram),velocitydensity crossplotting,correlation of porosities,pressure calculation and correlation,and comprehensive analyses.(3)With more and more application of empirical methods in the study of overpressure formation,almost all of the overpressure cases that are traditionally thought to be caused by disequilibrium compaction are denied totally or partly.Instead,the hydrocarbon generation is demonstrated to be the most significant mechanism for overpressure formation;the clay diagenesis(especially the smectiteillite transformation)as well as tectonic compression and pressure transfer are also important for overpressure formation.In addition,the overpressure formation in many basins is thought to be influenced by the combination of two or more overpressuring mechanisms.(4)Causes of overpressuring differ in lithology;for mudstones,the overpressure formation in source rocks is usually different from that of non-source rocks,the former of which is frequently related to hydrocarbon generation and sometimes also affected by diagenesis,while the later of which is commonly related to disequilibrium compaction,diagenesis and pressure transfer;for permeable rocks such as sandstones,overpressure is mainly caused by pressure transfer.(5)Because organic matter has an obvious influence on logging parameters such as density and acoustic velocity,an appropriate correction on the content of organic matter is needed when these logging data are used to analyze overpressure formation in organic-rich mudstones.It has been revealed that the cause of overpressuring based on the corrected log data can be quite different from that without correction.
