Impact of oxygen concentration and laser power on occurrence of intraluminal fires during shared-airway surgery: an investigation

2008 ◽  
Vol 122 (12) ◽  
pp. 1335-1338 ◽  
Author(s):  
V Dhar ◽  
K Young ◽  
S A R Nouraei ◽  
G S Sandhu ◽  
T Tatla ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Analysis Of Variance ◽  
Laser Power ◽  
Porcine Model ◽  
Tissue Injury ◽  
Ignition Time ◽  
Cent Oxygen ◽  
Average Standard Deviation ◽  
Time To Ignition ◽  
Power Setting

AbstractObjectives:Airway fires pose a risk during laser microlaryngoscopy, and neurosurgical cotton patties, used to prevent tissue injury from stray laser beams, are a potential ignition source. Using a configuration approximating clinical practice, we experimentally assessed the relative impact of changing different ‘fire triad’ components on the occurrence of airway fires, in order to better inform patient care.Methods:The relative effects of wet vs dry neurosurgical patties, oxygen concentration and laser power setting on the patty ignition time were studied in a cadaveric porcine model. Data were analysed using t-test and two-way analysis of variance.Results:Dry patties ignited after 2.3 ± 1.2 seconds (average ± standard deviation) of continuous 5 W laser fire at 50 per cent oxygen concentration, compared with 63.9 ± 27.8 seconds for wet patties under the same laser and oxygen settings (p < 0.0001). There was a statistically significant reduction in the time to patty ignition when laser power settings were increased from 5 to 7.5 W, but no further reductions occurred when the power was further increased to 10 W (p < 0.05; Tukey test for multiple comparisons; two-way analysis of variance). There was no significant reduction in the time to ignition between oxygen concentrations of 50 and 75 per cent, but the time to ignition fell significantly when the oxygen concentration was further increased to 100 per cent.Conclusion:We suggest that surgical patties should always be soaked and should be used for relatively short periods, in order to prevent drying. If at all possible clinically, prolonged laser use at high power settings and ventilation with 100 per cent oxygen should be avoided.

Laser Ignition of Surgical Drape Materials in Air, 50% Oxygen, and 95% Oxygen

2004 ◽  
Vol 100 (5) ◽  
pp. 1167-1171 ◽  
Author(s):  
Gerald L. Wolf ◽  
George W. Sidebotham ◽  
Jackson L. P. Lazard ◽  
Jean G. Charchaflieh
Keyword(s):  
Carbon Dioxide ◽  
Operating Room ◽  
Oxygen Concentration ◽  
High Energy ◽  
Ignition Source ◽  
Laser Ignition ◽  
Surgical Tools ◽  
Time To Ignition ◽  
Room Fires ◽  
Surgical Laser

Background Operating room fires fueled by surgical drapes and ignited by high-energy surgical tools in air and oxygen-enriched atmospheres continue to occur. Methods The authors examined the time to ignition of huck towels and three commonly used surgical drape materials in air, 50% oxygen, and 95% oxygen using a carbon dioxide surgical laser as an ignition source. In addition, a phenol-polymer fabric was tested. Results In air, polypropylene and phenol polymer do not ignite. For polypropylene, the laser instantly vaporized a hole, and therefore, interaction between the laser and material ceased. When tested in combination with another material, the polypropylene time to ignition assumed the behavior of the material with which it was combined. For phenol polymer, the laser did not penetrate the material. Huck towels, cotton-polyester, and non-woven cellulose-polyester ignited in air with decreasing times to ignition. All tested materials ignited in 50% and 95% oxygen. Conclusion The results of this study reveal that with increasing oxygen concentration, the time to ignition becomes shorter, and the consequences become more severe. The possibility exists for manufacturers to develop drape materials that are safer than existing materials.

Effect of oxygen concentration and temperature on ignition time of polypropylene

2012 ◽  
Vol 110 (1) ◽  
pp. 485-487 ◽  
Author(s):  
Jozef Martinka ◽  
Karol Balog ◽  
Tomáš Chrebet ◽  
Emília Hroncová ◽  
Janka Dibdiaková
Keyword(s):  
Oxygen Concentration ◽  
Ignition Time ◽  
Effect Of Oxygen

scholarly journals Examination of attitudes of secondary school 6th classstudents related to their attitudes towards maths in the frame of several variables

2016 ◽  
Vol 13 (1) ◽  
pp. 1937
Author(s):  
Kerim Karabacak ◽  
Subhan Eksioglu ◽  
Nesibe Karakıs
Keyword(s):  
Standard Deviation ◽  
Secondary School ◽  
Analysis Of Variance ◽  
Educational Status ◽  
Sixth Grade ◽  
T Test ◽  
Average Standard Deviation ◽  
Statistical Process ◽  
Several Variables ◽  
Purposeful Sampling

This research, which is carried out in Kinik, İzmir, aims at determining the reasons of students’ attitude towards Maths. Sixth class students from Kinik town make up population of the research which has been carried out as the model of survey. The sample of the research has been determined by the method of “purposeful sampling”. It is constituted of 152 students at the sixth grade. Collected data has been transferred into SPSS and the statistical process such as, analysis of average, standard deviation, T-test and one way analysis of variance procedures have been realized. It has been identified that the students who gets higher grades at Maths have got better attitude towards Maths than the ones who got lower grades at Maths. It has been identified that there has been no relationship between the students’ attitude towards Maths and their families’ income, their parents’ educational status, their parents’ occupation and the teachers’ way of teaching.

scholarly journals Endoscopic Ultrasound-Guided Radiofrequency Ablation (EUS-RFA) of the Pancreas in a Porcine Model

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Monica Gaidhane ◽  
Ioana Smith ◽  
Kristi Ellen ◽  
Jeremy Gatesman ◽  
Nagy Habib ◽  
...  
Keyword(s):  
Radiofrequency Ablation ◽  
High Frequency ◽  
Porcine Model ◽  
Tissue Injury ◽  
Pancreatic Head ◽  
Minimal Amount ◽  
Coagulative Necrosis ◽  
Ultrasound Guided ◽  
Distal Pancreas ◽  
Minimal Evidence

Backgrounds. Limited effective palliative treatments exist for pancreatic cancer which includes surgery or chemotherapy. Radiofrequency ablation (RFA) uses high frequency alternating current to ablate diseased tissue and has been used to treat various tumors. In this study, we evaluated a prototype probe adjusted to the EUS-needle to perform EUS-RFA to permit coagulative necrosis in the pancreas.Methods. Five Yucatan pigs underwent EUS-guided radiofrequency ablation of the head of their pancreas. Using an EUS-needle, RFA was applied with 6 mm and then 10 mm of the probe exposed at specific wattage for preset durations.Results. Only one pig showed moderate levels of pancreatitis (20% proximal pancreatitis). The other animals showed much lower areas of tissue damage. In 3 of the 5 pigs, the proximal pancreas showed greater levels of tissue injury than the distal pancreas, consistent with the proximity of the tissue to the procedure site. In 1 pig, both proximal and distal pancreas showed minimal pancreatitis (1%). There was minimal evidence of fat necrosis in intra-pancreatic and/or extra-pancreatic adipose tissue.Conclusion. EUS-guided RFA of the pancreatic head with the monopolar probe through a 19-gauge needle was well tolerated in 5 Yucatan pigs and with minimal amount of pancreatitis.

scholarly journals A novel approach to off-clamp partial nephrectomy demonstrates significant improvements in renal injury in an experimental porcine model

2017 ◽  
Vol 11 (10) ◽  
pp. E390-5 ◽  
Author(s):  
Daniel Olvera-Posada ◽  
Shouzhe Lin ◽  
Ghaleb Aboalsamh ◽  
Aaron Haig ◽  
Ian Lobb ◽  
...  
Keyword(s):  
Partial Nephrectomy ◽  
Histological Analysis ◽  
Porcine Model ◽  
Tissue Injury ◽  
Ischemia Reperfusion ◽  
Tissue Oxygen Saturation ◽  
Standard Group ◽  
Apoptotic Markers ◽  
Group 2 ◽  
Group 1

Introduction: We sought to design a partial nephrectomy (PN) with contralateral total nephrectomy porcine model and assess the underlying mechanisms of ischemia reperfusion injury (IRI) after PN using a novel, clinically approved resection device.Methods: Domestic male pigs (n=9) underwent left lower pole PN, allocated to either standard (Group 1) or no ischemia PN (Group 2), followed by contralateral nephrectomy. Biochemical studies were performed at baseline, Day 2, and Day 7; after sacrifice, kidneys were processed for histological analysis. Apoptotic markers were measured by Western blot analyses. Urinary biomarkers were measured to assess acute kidney injury.Results: At Day 2 following PN, there was a significant rise in serum creatinine in Group 1 compared to Group 2 (355 vs. 136 mmol/L; p=0.008). Intra-renal tissue oxygen saturation after PN was inversely correlated with postoperative creatinine (rs -0.75; p=0.012) and the grade of acute tubular necrosis (rs -0.70; p=0.036). We observed a rise in expression of pro-apoptotic markers and pro-inflammatory markers in Group 1 following PN compared to Group 2. Histological analysis revealed higher grade of apoptosis in Group 1.Conclusions: IRI associated with standard PN has a deleterious impact on acute renal function, markers of tissue injury, and histological parameters, compared to off-clamp PN using the ALTRUS device. We identified several intraoperative and postoperative markers that may be used as predictors for functional and histological injury following PN.

scholarly journals Tissue coagulation in laser hemorrhoidoplasty – an experimental study

Open Medicine ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 185-189 ◽  
Author(s):  
Donatas Danys ◽  
Julius Pacevicius ◽  
Gabija Makunaite ◽  
Rolandas Palubeckas ◽  
Antanas Mainelis ◽  
...  
Keyword(s):  
Diode Laser ◽  
Laser Power ◽  
Tissue Injury ◽  
Laser Exposure ◽  
Activation Time ◽  
Coagulation Defect ◽  
Significant Difference ◽  
Perianal Tissue ◽  
The Subject ◽  
A New Technique

AbstractBackgroundLaser hemorrhoidoplasty (LHP) is a new technique for treatment of hemorrhoids. The exact extent of coagulation is not visible at the time of the procedure. There currently is no experimental or clinical data on the subject.ObjectiveTo evaluate the length of coagulation defect according to power and activation time of 1470nm diode laser on the perianal tissue model.MethodsFresh anorectal tissue of twenty-four pigs was used to produce 54 experimental samples. Each sample was randomly assigned to the laser power of 6, 8 and 10 W and 1, 2 or 3-second pulses. The procedure was performed using Biolitec Ceralas © diode laser with 1.85 mm optical fiber. The fiber was inserted in a manner, similar to intrahemorrhoidal laser application. Samples were evaluated using low-power and high-power light microscopy by a single pathologist. The length of tissue injury was measured on high-magnification microscopy.ResultsThe longest tissue injury (mean 3.93 mm) was caused by the longest laser exposure time (3 sec) with no significant difference between laser power used.Conclusions8 W 3-second application of the 1470nm diode laser results in coagulation area approximately 4 mm, and further coagulation should be initiated approximately 5 mm from the first one.

scholarly journals THE TOTAL LUMINOUS EFFICIENCY OF LUMINOUS BACTERIA

1925 ◽  
Vol 8 (2) ◽  
pp. 89-108 ◽  
Author(s):  
E. Newton Harvey
Keyword(s):  
Power Plant ◽  
Oxygen Concentration ◽  
Luminescence Intensity ◽  
Sea Water ◽  
Luminous Efficiency ◽  
Pure Oxygen ◽  
Cent Oxygen ◽  
Maximum Value ◽  
Cent Efficiency ◽  
Luminous Bacteria

Methods are described for measuring the light emitted by an emulsion of luminous bacteria of given thickness, and calculating the light emitted by a single bacterium, measuring 1.1 x 2.2 micra, provided there is no absorption of light in the emulsion. At the same time, the oxygen consumed by a single bacterium was measured by recording the time for the bacteria to use up .9 of the oxygen dissolved in sea water from air (20 per cent oxygen). The luminescence intensity does not diminish until the oxygen concentration falls below 2 per cent, when the luminescence diminishes rapidly. Above 2 per cent oxygen (when the oxygen dissolving in sea water from pure oxygen at 760 mm. Hg pressure = 100 per cent) the bacteria use equal amounts of oxygen in equal times, while below 2 per cent oxygen it seems very likely that rate of oxygen absorption is proportional to oxygen concentration. By measuring the time for a tube of luminous bacteria of known concentration saturated with air (20 per cent oxygen) to begin to darken (2 per cent oxygen) we can calculate the oxygen absorbed by one bacterium per second. The bacteria per cc. are counted on a blood counting slide or by a centrifugal method, after measuring the volume of a single bacterium (1.695 x 10–12 cc.). Both methods gave results in good agreement with each other. The maximum value for the light from a single bacterium was 24 x 10–14 lumens or 1.9 x 10–14 candles. The maximum value for lumen-seconds per mg. of oxygen absorbed was 14. The average value for lumen-seconds per mg. O2 was 9.25. The maximum values were selected in calculating the efficiency of light production, since some of the bacteria counted may not be producing light, although they may still be using oxygen. The "diet" of the bacteria was 60 per cent glycerol and 40 per cent peptone. To oxidize this mixture each mg. of oxygen would yield 3.38 gm. calories or 14.1 watts per second. 1 lumen per watt is therefore produced by a normal bacterium which emits 14 lumen-seconds per mg. O2 absorbed. Since the maximum lumens per watt are 640, representing 100 per cent efficiency, the total luminous efficiency if .00156. As some of the oxygen is used in respiratory oxidation which may have nothing to do with luminescence, the luminescence efficiency must be higher than 1 lumen per watt. Experiments with KCN show that this substance may reduce the oxygen consumption to 1/20 of its former value while reducing the luminescence intensity only ¼. A partial separation of respiratory from luminescence oxidations is therefore effected by KCN, and our efficiency becomes 5 lumens per watt, or .0078. This is an over-all efficiency, based on the energy value of the "fuel" of the bacteria, regarded as a power plant for producing light. It compares very favorably with the 1.6 lumens per watt of a tungsten vacuum lamp or the 3.9 lumens per watt of a tungsten nitrogen lamp, if we correct the usual values for these illuminants, based on watts at the lamp terminals, for a 20 per cent efficiency of the power plant converting the energy of coal fuel into electric current. The specific luminous emission of the bacteria is 3.14 x 10–6 lumens per cm2. One bacterium absorbs 215,000 molecules of oxygen per second and emits 1,280 quanta of light at λmax = 510µµ. If we suppose that a molecule of oxygen uniting with luminous material gives rise to the emission of 1 quantum of light energy, only 1/168 of the oxygen absorbed is used in luminescence. On this basis the efficiency becomes 168 lumens per watt or 26.2 per cent.

Characteristics of low temperature and low oxygen diesel combustion with ultra-high exhaust gas recirculation

2007 ◽  
Vol 8 (4) ◽  
pp. 365-378 ◽  
Author(s):  
H Ogawa ◽  
T Li ◽  
N Miyamoto
Keyword(s):  
Oxygen Concentration ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Exhaust Gas Recirculation ◽  
Injection Timing ◽  
Exhaust Gas ◽  
Cent Oxygen ◽  
Low Oxygen ◽  
Gas Recirculation

Ultra-low NOx and smokeless operation at higher loads up to half of the rated torque is attempted with large rates of cold exhaust gas recirculation (EGR). NOx decreases below 6 ppm (0.05 g/kW h) and soot significantly increases when first decreasing the oxygen concentration to 16 per cent with cold EGR. However, after peaking at 12–14 per cent oxygen, soot then decreases sharply to essentially zero at 9–10 per cent oxygen while maintaining ultra-low NOx, regardless of fuel injection quantity and injection pressure. However, at higher loads, with the oxygen concentration below 9–10 per cent, the air-fuel ratio has to be over-rich to exceed half of the rated torque, and thermal efficiency, CO, and THC deteriorate significantly. As the EGR rate increases, exhaust gas emissions and thermal efficiency vary with the intake oxygen content rather than with the excess air ratio. Longer ignition delays due to either advancing or retarding the injection timing reduced the smoke emissions, but advancing the injection timing has the advantages of maintaining the thermal efficiency and preventing misfiring. A reduction in the compression ratio is effective to reduce the in-cylinder temperature and increase the ignition delay as well as to expand the smokeless combustion range in terms of EGR and i.m.e.p. (indicated mean effective pressure).

Studies on Coal Ignition and Combustion Characteristics

2017 ◽  
Author(s):  
Xue Chen ◽  
MingYan Gu ◽  
XianHui He ◽  
Dan Yan ◽  
Jimin Wang ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Coal Particle ◽  
Gas Flow ◽  
Ignition Time ◽  
Particle Diameter ◽  
Combustion Characteristics ◽  
Gas Temperature ◽  
Flow Temperature ◽  
Particle Ignition ◽  
Coal Particles

A 2-D numerical model of flow, heat transfer, and combustion of coal particles in a laminar gas flow at O2/CO2 atmosphere was developed based on the Eulerian-Lagrangian methodology. The gas-phase combustion was modeled using the GRI-Mech 3.0. The motion of coal particles was simulated using a trajectory model. The model was employed to study the coal ignition time, temperature and mass changes. The effects of particle diameter, the flow temperature and oxygen concentration on the ignition time and the combustion characteristics of coal particles were also investigated. The results obtained show that smaller size particle experiences a shorter ignition time with a higher coal temperature. A higher gas temperature leads to a shorter coal particle ignition time; increasing the flow temperature the difference in the ignition time of different sized coal particles decreases. The coal particle ignition time is decreased when the oxygen concentration is increased.

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