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PubMed1989

Toxicology of oil field wastes. Hazards to livestock associated with the petroleum industry.

In oil-producing states, the proximity of livestock to drilling operations and production sites often results in poisoning of animals from ingestion of crude oil, condensate, salt water, heavy metals, and caustic chemicals. The heavy metals encountered most frequently are lead from pipe joint compound and arsenicals and chromates used as corrosion inhibitors. Numerous toxic and caustic chemicals are used in drilling muds and fluids. Crude oil and salt water spills are common occurrences around production sites. Pipeline breaks may result in exposure of livestock to crude oil or refined petroleum hydrocarbons. Ingestion of petroleum hydrocarbons may result in sudden death from peracute bloat. The most common cause of illness or death following exposure to petroleum hydrocarbons is aspiration pneumonia, which may cause a chronic progressive deterioration of health, with death after several days or weeks. Cases in which livestock are exposed to oil, salt water, or caustic chemicals, but do not die acutely or from aspiration pneumonia are more frustrating to diagnose. In these cases, parasitism, poor nutrition, and other debilitating diseases must be considered. Anorexia, weight loss, and decreased rumen motility may be caused by a disruption of normal rumen function. Petroleum hydrocarbons, salt water, and caustic chemicals have the potential of altering rumen flora and enzymatic processes as well as damaging the ruminal and gastrointestinal epithelium. The toxicity of petroleum hydrocarbons appears to be related more closely to the volatility and viscosity of the product than to other factors. The more volatile straight chain and aromatic petroleum hydrocarbons have a greater potential for aspiration pneumonia and may produce an anesthetic-like action if absorbed systemically. The more volatile petroleum hydrocarbons also are more irritating to skin and mucous membranes and appear to be more damaging to rumen flora. Treatment of petroleum hydrocarbon ingestion is aimed at preventing aspiration pneumonia and the animal's absorption of highly volatile components. Activated charcoal slurries and, in some instances, vegetable oil may be used to absorb the ingested petroleum or alter its viscosity to minimize absorption and aspiration. These procedures should be followed by the administration of rumenatories or saline cathartics to hasten the evacuation of the gastrointestinal tract. Chronic poor performance animals with anorexia and rumen dysfunction may respond to fresh rumen inoculant, intravenous glucose, and B-complex vitamins. Prognosis primarily hinges on whether or not aspiration pneumonia has occurred. Treatment of aspiration pneumonia rarely is effe

Animals↗

PubMed2004

A standardised protocol for the acute management of corrosive ingestion in children.

Oesophageal strictures developing after caustic ingestion in children are a serious problem, and several protocols to prevent stricture formation have been proposed. A prospective clinical trial was conducted for preventing strictures in caustic oesophageal burns in a single clinic, and the results are presented. All children with caustic ingestion who had oesophagoscopy for diagnosing the severity of the burn were included in the study. Eighty-one children were included in the series, with ages ranging between 3 months and 12 years. The patients were given nothing by mouth until oesophagoscopy. IV fluids, broad-spectrum antibiotics, ranitidine, and a single-dose steroid were given. Oral burns were positive in 66 patients. Oesophagoscopy revealed a normal oesophagus in nine patients, grade 1 burn in 24, grade 2a in 21, grade 2b in 23, grade 3a in two, and grade 3b in one. Patients with grade 1 and 2a burns were discharged after oesophagoscopy. Patients with grade 2b and all grade 3 burns were given nothing by mouth for a week except water when swallowing their saliva, and were fed via total parenteral nutrition. After the 1st week, if there was no problem with swallowing, liquid foods were introduced. No intraluminal tubes were used. At the end of the 3rd week, a barium meal was administered and an upper gastrointestinal series taken. Dilatation was performed at 2-week intervals for strictures, which developed in one grade 2a patient, six grade 2b patients, and the grade 3b patient. Only one of these patients is currently on an oesophageal dilatation program. Limiting oral intake and avoiding foreign bodies in the oesophagus seem to provide a good success rate; however, further prospective studies are needed to decrease the incidence of corrosive oesophageal strictures.

Burns, Chemical↗

PubMed2000

Corrosive injuries of the esophagus in newborns.

To evaluate the morbidity and mortality of corrosive esophageal injuries (CEI) in the neonatal period, the records of 184 children hospitalized following caustic ingestion over a 10-year period from January 1987 to November 1997 were reviewed. Eight (4.3%) were newborns (5 boys and 3 girls). The mean age of the newborns was 12 days (range 1-28). The ingested caustic materials were benzalkonium chloride in six patients and trichloroacetic acid in two. Oropharyngeal examination and esophagoscopy were performed for diagnosis. Hyperemia and fibrin plaques were present in the oropharynx in all patients. The management consisted of endotracheal intubation, antibiotics, corticosteroids, and total parenteral nutrition. Pneumonia and sepsis developed in three patients and one died of sepsis. Stenosis developed in two patients, who were treated three times with antegrade dilatations. The morbidity was 62.5% (five patients) and the mortality was 12.5% (one) in newborns with CEI. These results indicate that ingestion of a caustic substance results in high morbidity and mortality in newborns. Parents and nurses should be warned about this risk.

Benzalkonium Compounds↗

PubMed1999

Gastric outlet obstruction due to corrosive ingestion: incidence and outcome.

A retrospective clinical study was performed to determine the incidence, management, and outcome of gastric outlet obstruction (GOO) caused by caustic ingestion in children. Of 220 patients who sustained caustic substance ingestion and were treated at our unit between 1976 and 1996, 168 ingested alkaline substances; of these, 9 children (5.3%) developed GOO in addition to esophageal strictures. The remaining 52 patients ingested acid agents, and 2 of them (3.8%) presented with GOO without esophageal strictures. The overall incidence of corrosive GOO was 5% (n = 11). The mean age of the patients with GOO was 5.7 +/- 2.8 years (range 2-14) with a female:male ratio of 6:5. Sodium hydroxide (n = 6), potassium hydroxide (n = 3), and hydrochloric acid (n = 2) were the ingested caustic agents. The patients were subdivided into two groups according to serial endoscopic and radiologic findings: group I: moderate (dense superficial and spotty ulcerations with intact mucosa) mucosal injury with partial pyloric obstruction; and group II: severe (deep ulcerations, extreme hemorrhagic erosions, eschar formation with white plaques) mucosal injury with complete pyloric obstruction. Group I consisted of 5 patients who ingested alkali agents while group II included 6 who presented with ingestion of alkaline (n = 4) and acid (n = 2) agents. Surgical treatment included Billroth I (n = 6) operations performed in group II and Finney (n = 3) and Heineke-Mikulicz (n = 2) pyloroplasty procedures done in group I. All patients are alive without any complaints. Fiberoptic endoscopy should be the preferred method of evaluating a patient with ingestion of a corrosive agent. It determines the presence of injury and assesses the extent of damage, establishing the diagnosis and allowing therapy to be instituted immediately. Our experience revealed that substantial damage has occurred early after ingestion, and early surgical intervention has decreased the morbidity and mortality. The extent of the mucosal injury and status of the pylorus and antrum determined the type of surgical treatment. A Billroth I procedure recommended for severely injured mucosa with complete pyloric obstruction, and pyloroplasty for moderate mucosal injury associated with partially obstructed but still viable pylorus. In contrast to the current belief, alkali ingestion also has a high risk of corrosive gastric injury causing GOO, which should be considered during assessment of the injury. We emphasize that a detailed evaluation of radiologic and especially endoscopic findings is very important for determining the timing, necessity, and type of appropriate surgical treatment.

Alkalies↗

PubMed1990

A controlled trial of corticosteroids in children with corrosive injury of the esophagus.

BACKGROUND: It is controversial whether treatment with corticosteroids reduces stricture formation in the esophagus after the ingestion of caustic material. METHODS: We conducted a prospective study over an 18-year period in which 60 children (median age, 2 years) with esophageal injury from the ingestion of caustic material were assigned randomly to treatment either with or without corticosteroids. The corticosteroids were given initially as prednisolon (2 mg per kilogram of body weight per day intravenously) and then as prednisone orally to complete a three-week course. All patients were evaluated by esophagoscopy within 24 hours of the ingestion. Those with moderate or severe esophageal injury had repeat esophagoscopy and barium swallow at follow-up. RESULTS: Esophageal strictures developed in 10 of the 31 children treated with corticosteroids and in 11 of the 29 controls (P not significant). Four children in the steroid group and seven in the control group eventually required esophageal replacement (P not significant). All but 1 of the 21 children with strictures had severe circumferential burns on initial esophagoscopy. CONCLUSIONS: There appears to be no benefit from the use of steroids to treat children who have ingested a caustic substance. The development of esophageal stricture was related only to the severity of the corrosive injury.

Administration, Oral↗

PubMed2006

Serious injuries from dishwasher powder ingestions in small children.

AIMS: To describe patterns and severity of caustic injuries sustained from dishwasher powder ingestion and highlight need for national safety standards. METHODS: Retrospective chart review of admissions for caustic ingestion to Starship Children's Hospital from January 2003 to January 2005 and review of New Zealand National Poisons Centre data. RESULTS: Between January 2003 and January 2005, the National Poisons Centre recorded 610 dishwashing powder ingestions, with 88% of children less than 2 years old. Twenty-three children were admitted to Starship Children's Hospital following caustic ingestion, of whom 11 were identified as having ingested dishwasher powder (9 boys and 2 girls) and were aged 11 to 30 months (mean 17.5). Five children (45%) were admitted to the Paediatric Intensive Care Unit over 4 months (October 2004 to January 2005), requiring intubation for airway control. Two children needed tracheostomy. Three of the 11 children (27%) required repeated oesophageal dilatation, and two underwent gastrostomy formation. One brand of dishwasher detergent and container type was implicated in over half of the cases. CONCLUSIONS: Dishwasher detergents are highly corrosive substances that cause potentially life-threatening injuries and ongoing morbidity. The recent surge of incidents may be related to change in product constituents or non-compliance with New Zealand safety standards. Efforts to limit product alkalinity, legislative requirement of Child-Resistant Packaging and public education may reduce injuries from these common household substances.

Accidents, Home↗

PubMed1983

The effect of PGF2 alpha on human and rat oral mucosa.

PGF2 alpha exerts a cytoprotective effect on the oral mucous membrane against the caustics, trichloroacetic acid and silver nitrate. The prophlogistic effect of PGF2 alpha and a caustic agent acting synergistically is an exaggerated inflammatory reaction (caustic-prostaglandin reaction or CPR). Intraperitoneal pretreatment with PGF2 alpha can prevent this CPR in rats. Probably the prostaglandin pretreatment depresses the PG receptors. Intraperitoneal pretreatment with indomethacin evokes a more marked CPR in rats. Probably the indomethacine pretreatment activates the PG receptors. Histological sections of the rat oral mucosa show a much less marked reaction after PGF2 alpha pretreatment. They also show signs of more marked swelling after indomethacin pretreatment.

Adult↗

PubMed1994

Management for acute corrosive injury of upper gastrointestinal tract.

BACKGROUND: It is imperative that the surgeon promptly determine the severity of any acute injury of the upper gastrointestinal (UGI) tract by caustic material ingested and the definite therapy be instituted. Prognostic factors of such injuries have not been clearly demonstrated in previous reports. Here, some prognostic factors and recommended emergency surgical indications in clinical assessment are discussed. METHODS: Forty-six patients (22 men and 24 women; age range 19 to 77 years), sustaining acute corrosive injuries to the UGI tract, were retrospectively assessed from November 1990 to May 1993. Immediate management was given to prevent shock, to identify any associated injury and to observe patency of the airway. Emergency operation was performed if any signs of peritonitis, mediastinitis or sepsis were present. Age, sex, time interval between ingestion and initial resuscitation, consciousness, peritoneal sign, shock index, pH value and [HCO3-] in arterial blood gas were evaluated as prognostic factors with respect to mortality. Chi-square test with Yates' correction was used. A p value less than 0.05 was regarded as statistically significant. RESULTS: Suicide attempt by caustic ingestion was in 40 patients (87%) and ingestion was accidental in 6 (13%). Acidic injury was specified in 36 patients (78.3%). In 14 severely injured patients, emergency exploratory laparotomy with or without esophagogastrectomy was performed in 9 (19.6%), of whom 2 survived. The other five patients were treated conservatively, and all died. Overall mortality rate was 26.1% (12/46). A significantly higher mortality rate was observed in patients with age > or = 50 years, positive peritoneal sign, shock index > 1, pH below 7.2 and bicarbonate concentration below 16 mEq/L as revealed by arterial blood gas (p < 0.05). CONCLUSIONS: The prognostic factors related to a higher mortality rate included age 50 years old or more, positive peritoneal sign, shock index above 1, pH below 7.2 and [HCO3-] below 16 mEq/L in arterial blood gas. Recognition of these factors indicates further detailed study will be required to propose a caustic injury score for predicting severity. Nevertheless, emergency operation is recommended if there are positive signs of peritonitis or mediastinitis, shock index above 1, pH below 7.0 and [HCO3-] below 10 mEq/L in arterial blood gas.

Acute Disease↗

PubMed1977

[Surgical attitude in pre-pyloric stenosis due to corrosive substances. Intravascular segmental antrectomy in Y-V. Report of 80 cases (author's transl)].

The author reports 80 cases of gastric stenosis due to caustic substances, of which 20 were limited only to the stomach and 60 were accompanied by esophageal stenosis. In most cases (78.8 p. cent), the site of the gastric stenosis was antral, pre-pyloric and the duration of onset was, on average, 3 weeks. Surgical treatment depended on the extent of the corrosive lesions. In limited antral stenosis, we carried out antrectomy with gastroduodenal anastomosis. In pre-pyloric stenosis situated 3 to 5 cm from the pylorus, the author recommends conservation of the non-functioning pylorus by double pylorotomy and anastomosis with the whole of the border of the stomach, describing a personal procedure named intravascular Y-V segmental antrectomy. The criterion which decides the proximal border of the resection, should be the appearance of the gastric mucosa, the section should pass immediately above the caustic ulceration. In extensive gastric stenosis (more than 75 p. cent) of the stomach and in evolutive corrosive lesions, we recommend Y-shaped jejunostomy, of Maydl type. In post-caustic pre-pyloric stenosis we operated on 76 cases out of 80 with 3 deaths (3.9 p. cent mortality). In 25 patients we carried out esophagoplasty about 6 months after the accident. We preferred restrosternal isoperistaltic coloesophagoplasty by Kelling's procedure. To increase the circulation through the left colic artery and marginal artery, we ligatured the middle colic artery and right colic artery at the same time as the gastrostomy.

Adult↗

PubMed1991

Endoscopy-guided balloon dilatation of esophageal strictures and anastomotic strictures after esophageal replacement in children.

This study evaluates the safety, efficacy, and technical problems of the new technique of endoscopy-guided balloon dilation (EGBD) in the treatment of strictures of the esophagus and its replacement. Between 1986 and 1990, the authors treated 33 children (aged 3 weeks to 20 years) with EGBD; 18 had esophageal strictures (primary esophageal atresia repair, 13; reflux esophagitis, 5), 13 had anastomotic strictures after esophageal replacement (colon, 12; stomach, 1), and 2 had caustic strictures. The majority (23 of 33) had previously failed to respond to conventional bouginage (mean, 11.2 sessions; range, 1 to 32 sessions). EGBD was performed using flexible endoscopy and flouroscopic screening under general anesthesia. Endoscopy identified and resolved the errors or uncertainties of preoperative contrast studies in 7 patients, 5 of whom had colon interposition. EGBD was achieved in all 31 patients with esophageal or replacement strictures; the mean number of EGDB procedures per patient was 2.1 (range 1 to 7). Symptomatic relief was excellent in 24 and moderate in 7 patients. Both patients with caustic strictures had esophageal perforation from EGBD (excessive inflation, 1; false passage of guide wire, 1). Patients who had experienced both conventional bouginage and EGBD noticed less pain with EGBD and resumed eating sooner. The authors conclude that EGBD is safe and effective for treating esophageal and replacement strictures but not caustic strictures.

Adolescent↗

PubMed2005

Beneficial effects of Ebselen on corrosive esophageal burns of rats.

AIM: This study was evaluated to investigate the efficacy of Ebselen, which is an organoselenium compound and glutathione peroxidase mimic, on the prevention of stricture development after esophageal caustic injuries in the rat. METHODS: Thirty healthy male Wistar albino rats were utilized in this study. The rats were randomly allotted into one of three experimental groups: group A (sham) animals were uninjured. Caustic esophageal burn was created by applying 1 ml of 37.5% NaOH to the distal esophagus. Group B rats were injured but untreated. Group C rats were injured and received Ebselen (10 mg/kg/day) via the oral route. Blood and tissue samples for the biochemical and histopathological analysis were taken all rats at the end (28th day) of the experiment. Oxidative stress is believed to play a role in the pathogenesis of corrosive esophageal burns. To assess changes in the cellular antioxidant defense system, we measured the activities of antioxidant enzymes (such as glutathione peroxidase (GSHPx), superoxide dismutase (SOD), and catalase (CAT)) in esophagus homogenates. We also measured esophageal tissue malondialdehyde (MDA) levels, a marker of lipid peroxidation, to determine whether there is an imbalance between oxidant and antioxidant status. Efficacy of the treatment was assessed by measuring the stenosis index and histopathologic damage score and biochemically by determining tissue hydroxyproline content, lipid peroxidation and antioxidant enzyme levels. RESULTS: The stenosis index in group B was significantly increased compared with group A and C (P<0.05). The hydroxyproline level was significantly increased in group B compared with group A and C (P<0.05). In group B, the histopathologic damage score was significantly higher than in group C (P<0.05). Treatment with Ebselen decreased tissue hydroxyproline levels, histological damage, and the stenosis index. Caustic esophageal burn increased the lipid peroxidation and also decreased the antioxidant enzyme levels in group B. Ebselen treatments for 28 days decreased the elevated lipid peroxidation and also increased the reduced antioxidant enzyme levels. Live weights of the rats was significantly decreased in group B compared with group A and C (P<0.05). CONCLUSION: It is concluded that Ebselen has a preventive effect in the development of fibrosis and decrease the lipid peroxidation, and increase the antioxidant defense system activity in an experimental model of corrosive esophagitis in rats.

Analysis of Variance↗

PubMed2005

Adsorption mechanism of synthetic reactive dye wastewater by chitosan.

Chitosan was able to remove the color from synthetic reactive dye wastewater (SRDW) under acidic and caustic conditions. The effect of the initial pH on SRDW indicated that electrostatic interaction occurred between the effective functional groups (amino groups) and the dye under acidic conditions. Moreover, SRDW adsorption under caustic conditions was also affected by the covalent bonding of dye and hydroxyl groups of chitosan. In addition, elution tests confirmed that chemical adsorption occurred under acidic conditions, while both physical and chemical adsorption appeared under caustic conditions. The spectra of attenuated total reflectance Fourier transform infrared spectrometry confirmed the functional groups of chitosan that affected the SRDW adsorption. However, the maximum adsorption capacities of chitosan increased when the temperature increased. The maximum adsorption capacity of chitosan obtained from the Langmuir model was 68, 110, and 156 mg g(-1) under a system pH of 11.0 at 20, 40, and 60 degrees C, respectively. The negative values of enthalpy change (DeltaH), free energy change (DeltaG), and entropy change (DeltaS) indicated an exothermic, spontaneous process and decreasing disorder of the system, respectively. Therefore, the mechanism of SRDW adsorption by chitosan was probably by chemical adsorption for a wide range of pH's and at high temperatures.

Journal Article↗

PubMed1984

Colon interposition for benign esophageal disease: experience with 23 patients.

Twenty-four colon interpositions were performed in a group of 23 patients comprising both adults and children between 1965 and early 1982. The indications for operation were caustic injury in 13 patients, peptic stricture in 6, congenital atresia or stenosis in 2, and gunshot or foreign body injury in 2. Long colon segments, consisting of isoperistaltic left colon in seven instances, antiperistaltic left colon in four, and right colon in five, were utilized for 16 procedures in 15 patients. Short segments of left colon were used in 8 patients, isoperistaltic in 6 and antiperistaltic in 2. There were no operative deaths. Ischemic complications necessitated removal of the transplant and replacement with another segment in 1 patient and revision or drainage procedures in 2 others. Strictures of the esophagocolic anastomosis occurred in 6 patients. Five of these strictures occurred among the 13 patients with caustic injury and appeared to be due to unrecognized caustic damage in the esophageal segment used for the anastomosis. Three patients died of unrelated causes eight months to 4 1/2 years after operation, and 3 others were lost to follow-up. Seventeen patients were available for current follow-up 1 to 16 years after operation, including 7 who were followed more than 7 years. When the swallowing ability of these 17 patients was assessed using rigorous criteria, 9 were found to have an excellent to good result; 5, a good to fair result; and 3, a poor result. No patient showed late deterioration of function. We conclude that interposed colon is the ideal esophageal substitute for the patient with benign disease.

Adolescent↗

PubMed2004

Ingestion of acid and alkaline agents: outcome and prognostic value of early upper endoscopy.

BACKGROUND: Ingestion of caustic substances often leads to severe morbidity and, frequently, death. This study compared complications and survival for patients who ingested an acidic substance, mainly glacial acetic acid, or an alkaline agent. METHODS: Records for 179 patients hospitalized for ingestion of a caustic agent (85 acid [75 glacial acetic acid], 94 alkali) were reviewed. Mucosal injury, systemic and GI complications, and survival were scored. RESULTS: Outcome was less favorable for patients who ingested acid compared with those who ingested alkali with respect to mucosal injury (median: grade 2 vs. grade 1; p=0.013), hospital stay (mean: 9.9 vs. 7.2 days; p=0.01), admittance to the intensive care unit (44% vs. 22%; p=0.002), systemic complications (24% vs. 3%; p < 0.001), perforation (6% vs. 0%; p=0.017), and mortality (14% vs. 2%; p=0.003). There was no difference in the development of strictures (acid, 15% vs. alkali, 17%). The grade of mucosal injury at endoscopy was the strongest predictive factor for the occurrence of systemic and GI complications and mortality (relative risk 9: 95% CI[3, 30]). Ten of 29 (34%) patients with strictures were treated by endoscopic dilation alone, whereas the others primarily (n=7) or secondarily (n=11) underwent surgery. One patient with an esophageal stricture died from systemic complications. CONCLUSIONS: Acid ingestion, particularly glacial acetic acid, is associated with a higher frequency of complications and mortality rate than alkali ingestion. Early endoscopy probably is safe and provides important prognostic information. Endoscopic treatment of caustic-induced strictures is only moderately successful.

Accidents↗

PubMed1996

Iatrogenic esophageal perforation in children: patterns of injury, presentation, management, and outcome.

Iatrogenic esophageal perforations in children are rare. To evaluate patterns of injury, clinical presentation, and treatment options for such patients, the authors reviewed the case records of 11 children who had sustained transmural injury to the esophagus during a dilatation procedure at their institution between 1967 and 1994. Strictures requiring dilatation were attributable to caustic ingestion in eight, esophageal atresia repair in two, and congenital stenosis in one. Eight were penetrating injuries, and three were disruptions. Two involved the cervical esophagus; and nine involved the thoracic esophagus. Pain, pyrexia, and tachycardia were early signs. Proximal thoracic perforations led to signs in the left chest region (effusion/pneumothorax); with distal perforation the signs were on the right side. Treatment along conventional lines (local drainage, gastrostomy, primary repair after early recognition, and antibiotic therapy) was successful, with two major complications, both empyemas. The most recent case, a disruption of a tracheoesophageal fistula stricture, was successfully treated with oral water irrigation and antibiotics only. Six had colonic interposition (all caustic ingestion), one required endoesophageal resection of a distal stricture, and four had resolution of the stricture, three without additional dilatation. The majority of children with iatrogenic injuries of the esophagus can be managed successfully by conservative measures and pleural drainage, with surgical procedures reserved for large disruptions of the esophagus, intraabdominal perforations, and cases that do not respond to appropriate conservative measures. Patients with caustic injury to the esophagus have a greater risk for the development of penetrating injury, and this may be one indicator of the severity of scarring. There are distinct clinical patterns of presentation, which depend on the level at which the esophagus is perforated. Dilatation disruption of a localized stricture has a good long-term prognosis for the esophagus and may even cure the stricture. The role of oral irrigation still must be fully evaluated where disruption has occurred as distinct from a penetrating injury.

Adolescent↗

PubMed2004

[Clinical aspects of corneal burns].

Clinical aspects and prognosis of corneal burns mainly depend on the agent responsible for the trauma. The most severe burns are caustic burns, which should be classified as burns caused by basic agents, associated with deep and prolonged injuries, and burns caused by acidic agents, associated with more superficial injuries. At the acute stage, caustic burns induce epithelial defects, corneal edema, and ischemic necrosis of the limbus, conjunctiva, iris and ciliary body. At the early stage, reepithelialization occurs and is often associated with corneal vascularization and stromal infiltrates, followed by corneal scar formation. At the chronic stage, the following complications are possible: corneal scars, limbal stem cell insufficiency, lachrymal insufficiency, irregular astigmatism, ocular surface fibrosis, cataract, glaucoma, decreased intraocular pressure, and ocular atrophy. The Ropper-Hall classification is based on the extent of limbal ischemia. Thermal burns induce epithelial defects at the acute stage, with the more severe forms giving the same complications as caustic burns. Radiation-related burns can be caused by ultraviolet radiations (acute epithelial keratitis, pterygium, droplet-like keratitis), microwaves, infrared radiations, ionizing radiations or, laser radiations. Electrical burns are often a result of torture and give corneal stroma opacification.

Corneal Injuries↗

PubMed2000

Integrated hydrometallurgical process for production of zinc from electric arc furnace dust in alkaline medium.

In this study, a novel and integrated hydrometallurgical process for the production of zinc powder from electric arc furnace (EAF) dust in alkaline medium is reported. The dust is firstly hydrolysed in water, and then fused in caustic soda at 350 degrees C for 1h, followed by leaching in alkaline solution in which both zinc and lead are effectively extracted. Zinc powder is then produced by electrowinning from the leach solution after the lead is selectively removed by precipitation using sodium sulphide as precipitant. The EAF dust tested contained 25% Zn, 1.8% Pb and 33% Fe. It was found that 38% of zinc and 68% of lead could be extracted from the dust when leached directly in caustic soda solution. Leaching of zinc increased to 80% when dust was directly fused with caustic soda followed by alkaline leaching. However, the leaching further increased to 95% when the dust was hydrolysed first with water before fusion. Zinc powder with a purity of 99.95% was then produced by electrowinning from the lead depleted solution. Stainless electrodes were used as both anode and cathode.

Dust↗

PubMed1999

Observations on the optical effects of a cataract.

PURPOSE: To describe and measure the optical effects seen by a person with a cataract and to use these observations to deduce physical changes in the crystalline lens caused by the cataract formation. SETTING: Humphrey Systems, Dublin, California, USA. METHODS: Caustic patterns created on the retina by a bright point source of white light as that source is viewed at various far-point distances ranging from the anterior focal point of the eye to +15.00 diopters were observed. The subtended retinal angle of a diffractive ring of light created by a small bright source of white light was observed and measured. RESULTS: Three optical effects were seen and measured: multiple-image formation at certain far-point positions; a diffractive light ring surrounding small bright sources; a radial needle of bright light surrounding a small bright-white source. With a point source of light positioned at the anterior focal point of the eye, the Y sutures of the lens could be visualized. With the point source at other distances, characteristic caustic patterns could be visualized, allowing assessment of the lens' optical character. The subtended retinal angle of the diffractive ring was measured so the periodic lens structure could be evaluated. CONCLUSIONS: The lens acted refractively as if it were divided into 3 elements with noncoincident optical axes. These 3 segments were associated with areas defined by the Y sutures, causing 3 images to be formed at certain distances. The caustic patterns indicate that each segment is slightly toroidal with axes at about 120 degrees apart combined with overcorrected spherical aberration. The period structure creating the diffractive ring had a period of 10 microns, approximately the width of a cortical lens cell, indicating that fluid between the cells likely creates a diffractive phase grating.

Cataract↗