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The report is about argon embolism in a 37-year-old female patient during laparoscopic cholecystectomy and coagulation of a liver bed bleeding with the "Argon Beam One". The presented case report is to show that in spite of technical perfection and correct use of the Argon Beam One coagulator unfavorable anatomical conditions can cause life threatening gas embolism.
Color contrast sensitivity was measured in laser operators before and after laser use. After argon blue-green laser treatment sessions, sensitivity was reduced for colors lying along a tritan color-confusion line for several hours. This acute effect is due to specular "flash-backs" from the aiming beam off the surface of the contact lens. It is caused only by argon 488-nm light, when the aiming beam intensity is high. In addition, a correlation has been demonstrated between the number of years of laser experience and a chronic reduction in tritan color contrast sensitivity. It is suggested that repeated acute changes caused by the argon lasers may cause cumulative effects and produce a chronic threshold elevation. A simple method of eliminating the acute effect is documented.
A prospective, randomized, investigator-masked, parallel study compared the capability of five different intraocular pressure (IOP) lowering agents to prevent acute IOP elevations following argon laser trabeculoplasty. Two hundred sixty eyes (patients) received either apraclonidine 1% (125 eyes), pilocarpine hydrochloride 4% (37 eyes), timolol maleate 0.5% (35 eyes), dipivefrin 0.1% (32 eyes), or acetazolamide 250 mg (31 eyes) both 1 hour before and immediately following 360-degree argon laser trabeculoplasty. Apraclonidine was the only medication that significantly decreased mean IOP from baseline. Only 4 (3%) of the apraclonidine-treated eyes had IOP rises greater than 5 mm Hg. This frequency was significantly lower than that found in eyes treated with acetazolamide (39%), dipivefrin (38%), pilocarpine (33%), or timolol (32%).
The anterior segment of the eye of 100 rabbits was exposed to radiation from Argon, Ruby and YAG lasers. The healing process of liminal and supraliminal lesions was evaluated histologically. The iris is the most sensitive tissue for all three lasers (threshold radiant exposure, Argon: 0.004 kJ/cm2, Ruby: 0.01 kJ/cm2, YAG: 0.05 kJ/cm2). Higher energies necessary for lesions in the transparent media were available only with the Argon and YAG lasers. The Argon laser failed to produce lesions in the lens, and threshold radiant exposure for the central cornea was 8 kJ/cm2. The thresholds for YAG lasers lesions in the central cornea and lens were of the same magnitude. The marked absorption of energy by the iris may lead to an accumulation of heat, resulting in lesions of adjacent tissues or a reduction of threshold for those lesions: The threshold in the peripheral cornea was ten times lower than in the center with the Argon laser, four times lower for the YAG laser. The thresholds for Argon and YAG laser lesions in the peripheral sclera lay between the thresholds for the iris and for the peripheral cornea. A safety standard for the anterior segment of the eye should be based on the lowest threshold (Argon laser lesion of the iris). The application of a factor 100 results in a maximal permissible exposure of 40 mJ/cm2. The influence of the beam diameter could not be evaluated.
Eight human volunteers, individually studied in a hyperbaric chamber, breathed: 1) air at 1 ATA; 2) 80% argon and 20% oxygen and 1 ATA for 30 min; 3) air at 1 ATA for 30 min; 4) 100% 02 at 1 ATA for 30 min; 5) air at 1 ATA for 30 min; 6) 100% O2 at 2 ATA for 60 min; and 7) 80% argon and 20% oxygen at 1 ATA for 30 min. Oxygen, carbon dioxide, nitrogen, and argon tensions were measured in muscle and subcutaneous tissue by mass spectroscopic analyses. Venous blood obtained at regular intervals was analyzed for coagulation and fibrinolytic factors. Inert gas narcosis was not observed. After breathing argon for 30 min, muscle argon tensions were almost three times subcutaneous tensions. Argon wash-in mirrored nitrogen wash-out. Argon wash-in and wash-out had no effect on tissue Po2 or Pco2. Coagulation and fibrinolytic changes usually associated with vascular bubbles were absent.
CO2 and argon lasers have been used successfully for vascular welding in both experimental and clinical settings. This study compared the thermodynamics during CO2 and argon laser welding of 1-cm longitudinal arteriotomies in a canine model. Continuous recordings using an AGA 782 digital thermographic system with spatial and thermal resolution of +/-0.2 mm and +/-0.2 degree C, respectively, were analyzed. A HGM argon laser using a 300-microns optic fiber held at 1 cm from the vessel edges (spot diameter = 2.8 mm) with concomitant room temperature saline irrigation (1 drop/sec) was used for argon welds. Total exposure time was 150 sec/cm. CO2 welds were performed with a Sharplan CO2 laser (spot diameter = 0.22 mm) with no irrigation for total exposure time of 10 sec/cm. Thermodynamic results and laser parameters are summarized as follows: Argon-n = 20; power = 500 mW; energy fluence = 1,400 J/cm2; Tmax = 48.8 degrees C; T mean +/- S.D. = 45.1 +/- 2.7 degrees C; CO2-n = 20; power = 150 mW; energy fluence = 3,000 J/cm2; Tmax 84.0 degrees C; T mean +/- S.D. = 60.7 +/- 9.8 degrees C. There was a significant difference (P less than .05) in thermal measurements between successful CO2 and argon vascular welds. Temperature rise during the argon welds was limited by saline irrigation. In contrast, during CO2 laser welding, the temperature rose quickly to its maximum and was maintained at a relatively high level as the laser progressed (0.1 cm/sec) along the anastomosis.(ABSTRACT TRUNCATED AT 250 WORDS)
This study determined the optimum laser energy for ablation of colonic mucosal lesions and small sessile polyps in the canine colon. Neodymium (Nd):YAG laser, argon laser, and monopolar electrocautery were applied to exposed canine colonic mucosa for various application times at various power settings. At the minimum energy level necessary to ablate mucosa, the Nd:YAG laser caused greater muscularis injury than the argon laser and monopolar electrocautery. At higher energy levels, monopolar electrocautery and Nd:YAG laser caused greater muscularis injury than argon laser. Small surgically created polyps in the canine colon were ablated endoscopically with the three energy sources. Single-session complete polyp ablation occurred most frequently with Nd:YAG laser and least frequently with argon laser. The depth of tissue injury beneath polyp ablation sites was least with argon laser and greatest with Nd:YAG laser. This study suggests that the argon laser is safer than the Nd:YAG laser or monopolar electrocautery for coagulation of flat colonic mucosal lesions. Although the argon laser is safer for the coagulation of small sessile colonic polyps, it may be less effective than monopolar electrocautery or the Nd:YAG laser for the single-session fulguration of polyps greater than 5 mm in diameter.
Experiments were performed to determine the absorption by and transmission through blood of argon blue-green (ABG) and green (AG) and krypton red (KR) laser light. Krypton was transmitted better through intact erythrocytes than argon. The difference between krypton and argon was greater if the erythrocytes contained oxygenated hemoglobin (Hb) than deoxygenated Hb. None of the wavelengths penetrated well a confluent blood specimen only 4 cells thick. Branch retinal vein occlusions were created in monkeys causing scattered areas of retinal hemorrhage. Argon burns placed in areas of retinal hemorrhage caused much inner or full thickness retinal damage. Krypton passed through the inner retinal hemorrhage without causing damage and created a burn at the level of the retinal pigment epithelium and inner choroid. Preretinal hemorrhages were created in rabbits by perforating Bruch's membrane with a high intensity krypton burn. Argon burns placed over the preretinal hemorrhages were absorbed much more than krypton burns. Neither argon or krypton however could penetrate even moderately thick preretinal hemorrhages to cause an underlying retinal burn.
Two detection systems for gas-liquid chromatography were compared for the identification of metabolic end products (short-chain organic acids) from anaerobic bacteria. Argon and flame ionization detectors were connected in series with inert argon as the carrier gas for analysis of 35 stock strains and 148 clinical isolates. There was an excellent correlation between the argon and flame ionization chromatograms, and both were readily comparable to the thermal conductivity detector tracings published in the Virginia Polytechnic Institute manual. The linear response of the argon detector was examined by analyzing twofold serial dilutions of the short-chain organic acids and comparing the results to the very linear flame ionization detector. The argon detector was found to react with sufficient linearity within the organic acid concentration range normally obtained from anaerobic bacterial broth cultures. The argon detector, therefore, appears to be a viable alternative to the flame ionization and thermal conductivity detector systems in the identification of anaerobic organisms.
As chickens may rapidly regain consciousness after gas stunning, the effects of a two minute exposure to a carbon dioxide-argon mixture on survival rate were investigated. Broilers were stunned in batches of 10 per transport crate with a mixture of 10, 20 or 30 per cent carbon dioxide in argon with 5 per cent residual oxygen. The birds were exposed to the gaseous atmosphere for two minutes. A control group of birds was electrically stunned (120 mA for four seconds; 50Hz sinusoidal waveform). In addition, the incidence of carcase downgrading conditions after stunning with 20 per cent or 30 per cent carbon dioxide in argon with 5 per cent residual oxygen was compared with the incidence after electrical stunning. The results showed that stunning with 10 and 20 per cent carbon dioxide in argon with 5 per cent residual oxygen resulted in survival rates of 24 and 1 per cent, respectively. Stunning with 30 per cent carbon dioxide in argon with 5 per cent residual oxygen resulted in the death of all the broilers. Electrical stunning resulted in a significantly (P less than 0.001) larger number of broilers with breast muscle haemorrhaging and broken furculum and coracoid bones, whereas stunning with gas mixtures resulted in a significantly (P less than 0.001) higher incidence of broilers with damaged wing bones. Electrical stunning of broilers resulted in a significantly higher pH in the breast muscles 20 minutes post mortem than stunning with carbon dioxide-argon mixtures.(ABSTRACT TRUNCATED AT 250 WORDS)
We compared in rabbits the effects of laser iridotomy by either argon or neodymium (Nd):YAG laser on prostaglandin E2 (PGE2) production by the iris/ciliary body, its accumulation in the aqueous humor and the aqueous protein levels. PGE2 production by the iris/ciliary body, following exposure to argon or Nd:YAG laser, was similarly enhanced, with peak levels of 22.8 +/- 4.7 and 24.1 +/- 8.2 ng/mg, respectively. An increase in aqueous PGE2 levels was more pronounced in the argon as compared with the Nd:YAG group, with peak levels of 56.7 +/- 17.3 and 20.0 +/- 7.7 ng/ml, respectively. PGE2 production correlated well with aqueous PGE2 levels in the argon group, but not in the Nd:YAG group. Protein accumulated in the aqueous humor following irradiation by both types of laser light, with higher levels occurring in the argon group. These results are indicative of possible differences in the extent of the inflammatory reaction induced by the application of argon and Nd:YAG laser light to the iris.
A modified indicator gas washout method was developed to measure functional residual capacity (FRC) during high-frequency oscillatory ventilation (HFOV) without interruption of HFOV. A hot-wire flowmeter and medical gas analyzer measured the flow rate and argon concentration, respectively, at the expiratory end of the respiratory circuit. Upstream of the hot-wire flowmeter, two heat-and-moisture exchangers for resistance and a rubber balloon for capacitance were placed to convert the oscillating expiratory flow to an almost continuous flow. This made it possible to measure FRC during HFOV without interrupting HFOV. To measure the volume of the entire respiratory circuit, a 10 percent argon in 90 percent oxygen gas mixture was initially used as a bias flow, and after equilibration, the test gas was switched to 100 percent oxygen. By electrical integration of the product of the expiratory flow rate and argon concentration, the total amount of argon equilibrated in the entire respiratory circuit was calculated. The volume of the circuit was calculated by dividing the total amount of argon by the initial argon concentration. Functional residual capacity plus the volume of the respiratory circuit was similarly calculated and the difference was estimated as FRC. The accuracy and reproducibility of our method were evaluated by using a one-compartment lung model. There was a high correlation between the volume setting of the model lung and the estimated FRC. This method can be used to estimate FRC in a one-compartment lung model during HFOV, and it is potentially useful in clinical situations.
A retrospective review of all stapedectomies performed at the Massachusetts Eye and Ear Infirmary over a 13 month period was undertaken to compare the results of argon laser stapedectomy to conventional footplate fenestration techniques. Despite the fact that it was new and unfamiliar to the surgical staff, the complication rate was lower with the argon laser than with footplate fenestration by traditional pick or drill techniques. The incidence of footplate fracture or removal preventing use of a small fenestra technique was five times as likely to occur with traditional instruments as with the argon laser (p < 0.025). In revision stapedectomy sensorineural hearing loss was four times as likely to occur with traditional instruments as with the argon laser (p < or = 0.05). The argon laser did not alter the operating time. Though not ideal for every case, the argon laser endo-otoprobe offers the surgeon a significant new tool to improve the outcome in stapes surgery.
Eyes with three or four diabetic retinopathy risk factors received laser panretinal photocoagulation with random selection of either blue-green argon (42 eyes) or red krypton (40 eyes) laser to determine if one laser was superior to the other. After 6 months, visual acuity preservation or improvement was obtained in 33 (79%) argon- and 34 (84%) krypton-treated eyes. Peripheral IV-4e visual field constriction of 7% occurred with argon and 10% with krypton. Vitreous hemorrhaging after treatment occurred in 1 argon- and in 6 krypton-treated eyes. Complete disc neovascular regression was obtained in 27 (67%) of 40 argon- and 19 (56%) of 34 krypton-treated eyes, with partial regression occurring in 8 (20%) argon- and 8 (24%) krypton-treated eyes. The two treatments produced essentially equal results.
Recent studies demonstrated that the cationic, mitochondrial-specific dye Rhodamine-123 (Rh-123), is an efficient tumor photosensitizer for Argon laser treatment of human cancer cells both in vitro and in tumors grown as xenografts in athymic mice. To demonstrate the photodynamic mechanism of action of this reaction, the intracellular role of oxygen and temperature changes in treated cells have to be defined. In the current study, a large panel of human tumor cell lines of diverse histologic origin were tested for in vitro sensitivity to Rh-123 and the Argon laser (514.5 nm) in oxygen, deuterium oxide (D2O), and nitrogen (N2) environment. Tumor cells in suspension were first sensitized to Rh-123 (1 or 20 micrograms/ml for 1 hour), cooled on ice to 4 degrees C, and then exposed to the Argon laser (delta T = 14 +/- 1 degree C). Cell proliferation measured by [3H]-thymidine uptake 24 hours after sensitization with Rh-123 and laser treatment was significantly decreased in tumor cells kept in oxygen and D2O atmospheres. No decrease in DNA synthesis was seen in Rh-123 and laser treated cells kept in an N2 environment. Control tumor cells treated with Rh-123 or the Argon laser separately did not show any decreased [3H]-thymidine uptake in oxygen, D2O or N2 environment. These results provide evidence of a photodynamic process since Rh-123 sensitization and Argon laser activation occur at nonthermal levels of energy and are oxygen dependent. The high effectiveness of this technique of photodynamic therapy with the Argon laser, and low toxicity of Rh-123 could make its clinical use very attractive for the treatment of superficial malignancies.
Chromophore dyes can be employed to modify laser-tissue interaction. A number of dyes have been investigated for their effect on the absorption and transmission of argon and Nd:YAG laser energy by vascular tissue in vitro. Three histological dyes have been assessed as potential chromophores for the argon laser and four infrared dyes for the Nd:YAG. Segments of porcine coronary artery to which dye had been applied were lased (1,064 nm, 2.5 W, 83 W/cm2, 60 s and 488/514 nm, 400 mW, 10.5 W/cm2, 60s) and the tissue temperature measured remotely using an infrared thermometer. In addition, energy transmission was measured with a photodiode and tissue morphological changes assessed histologically. All three argon dyes significantly increased energy absorption (typically 60 degrees C v. 20 degrees C at 60 s, P less than 0.001, 2-way ANOVA). Three of the four infrared dyes behaved similarly (40-70 degrees C v. 20 degrees C, P less than 0.001). All dyes significantly increased the initial rate of rise in tissue temperature during lasing. A reduction in energy transmission was observed for each of the Argon dyes but not for the Nd:YAG dyes. Histological evidence of thermal damage in control tissue first occurred for the argon and Nd:YAG lasers at 800 mW and 7.5 W without chromophore and at 400 mW and 2.5 W with the chromophore, respectively. A number of effective chromophores have therefore been identified at each wavelength.
A previous investigation indicated that when hens were exposed to 2% oxygen in argon (anoxia) EEG suppression and loss of SEPs occurred at 17 and 29 s after exposure. In this study, hens were exposed to 49% carbon dioxide in air (hypercapnic hypoxia) or 31% carbon dioxide with 2% oxygen in argon (hypercapnic anoxia) and their spontaneous electroencephalogram (EEG) and somatosensory evoked potentials (SEPs) were investigated. The results indicated that EEG suppression and loss of SEPs occurred in 11 and 26 s, respectively, in hypercapnic hypoxia. These events occurred at 11 and 19 s, respectively, after exposure to hypercapnic anoxia. These results indicated that, with regard to preslaughter stunning/killing of chickens, a mixture of 31% carbon dioxide with 2% oxygen in argon resulted in a more rapid loss of evoked responses in the brain when compared with 49% carbon dioxide in air or with 2% oxygen in argon. It is concluded that stunning chickens with low concentrations of carbon dioxide in argon would result in a more rapid loss of consciousness.
Neodymium:YAG (Nd:YAG) and argon laser iridotomies were compared in a prospective, randomized clinical trial of 43 patients with bilateral chronic pupillary-block glaucoma. All patients had one eye randomly assigned to argon and the fellow eye assigned to Nd:YAG laser treatment. Follow-up ranged from 20 to 42 months. Iridotomy closure was not observed in Nd:YAG-treated eyes, but nine (21%) argon iridotomies required retreatment. Visual loss due to progression of laser-induced lens or corneal damage was not observed in any eye. Nine (21%) argon-treated eyes and eight (19%) Nd:YAG-treated eyes required laser trabeculoplasty for further intraocular pressure (IOP) lowering after iridotomy. Five (12%) argon-treated and two (5%) Nd:YAG-treated eyes required intraocular filtration surgery for long-term IOP control, but this difference was not statistically significant. There were no significant long-term differences between these treatment modalities.