Alexander Uribe MD, FACS

• Associate Professor of Surgery, Jefferson Medical College, Philadelphia,
• Pennsylvania
• Attending Surgeon, Lankenau Hospital, Wynnewood, Pennsylvania

This allows liquid nitrogen spray to enter the cone and rapidly freeze the lesion treatment quadriceps pain lquin 250 mg buy low cost. Another cone-apparatus option includes holding an otoscope cover tip against the lesion with one hand while freezing with the cryosurgical unit in the other hand medicine journal impact factor 250mg lquin purchase visa. Treatment times using the cone method should be decreased because the final temperature at the orifice of the cone is obtained faster medicine chest purchase 250mg lquin fast delivery, when compared with an open spray medications names and uses lquin 250mg otc. First medicine assistance programs cheap 250 mg lquin otc, a small amount of liquid nitrogen is poured into a polystyrene cup or other insulated container. Using firm pressure, the cotton-tips are placed against the lesion until a 2- to 3-mm halo forms around the treated lesion. This method is useful where surrounding tissue must be spared, such as periorbital, mucosal, nail, and genital regions. This method is useful for treating filiform lesions such as verrucae and skin tags. Although longer freeze times of 10­15 seconds with a 1- to 2-mm halo are required for these raised growths, too aggressive freezing may result in scarring or hyperpigmentation. For cosmetic purposes and to prevent pigmentation changes, a lighter freeze followed by curettage may be preferential. Freeze times of 30 seconds are required over 1-month interval sessions until flattening is achieved. Zouboulis et al reported a prospective study of 93 keloids and hypertrophic scars treated with 30-second freeze times over one to three sessions. A retrospective study of 393 dermatofibromas treated with cryosurgery reported 65% clearance of a visible and palpable lesion. Freeze times of 5­10 seconds are required, using the cryoprobe technique with the probe applied directly into the central punctum of the lesion. Cryosurgery using the spray technique is probably the most common method due to its quick, convenient use and ease of obtaining a freeze halo around the lesion. The cotton-tip applicator technique is cheaper and may be less frightening to the patient, particularly children. Care must be undertaken not to cross contaminate the liquid nitrogen by reintroducing the cotton-tip applicator into a common flask. Berth-Jones and Huchinson11 demonstrated a 52% cure rate at 3 months with the combination of cryotherapy, keratolytic wart paint, and paring. The authors also noted that paring the wart before cryotherapy improved the cure rates for plantar warts, but not hand warts. The open spray technique, using a single freeze-thaw cycle of 8­10 seconds, is the treatment of choice. Therefore, these lesions require a shorter freeze time of 3­5 seconds with minimal halo. For darker-skinned individuals, care must be taken not to induce hypopigmentation at treatment sites. Therefore, a test site in a cosmetically less noticeable region may be performed first before treating multiple lesions on sun-exposed areas. In addition, sunscreen with ultraviolet A and ultraviolet protection should be advocated post-treatment. For thicker lesions, pretreatment of emollients or curetting may shorten freezing times. In patients with diffuse actinic damage, extensive cryosurgery or cryopeeling, may be useful. The lesion is subsequently treated with a double freeze-thaw cycle of 30­60 seconds each cycle. Because atypical melanocytes may extend along the length of the hair follicles, treatment must freeze the tissue to this depth. One major disadvantage of cryosurgery is the inability to assess whether the lesion has been completely destroyed. In addition, because no tissue is obtained for definitive confirmation of cancer removal, the chance exists that recurrent melanoma may develop and that it may be invasive. The goal of cryosurgery is to cure the patient by destroying the lesion in a single treatment. The margins of destruction of the lesion cannot be assessed using cryosurgery of malignant tumors. The average healing time was 46 days, with lesions on the lower leg taking longer to heal (90 days). Lesions such as periungual warts, digital lesions, or mucous membrane lesions may require stronger analgesics due to intense swelling and throbbing. Furthermore, there are no good studies comparing cryosurgery with other known treatment modalities, such as Mohs micrographic surgery, excision with clinical margins, and electrodesiccation and curettage. If painful hemorrhagic bullae form, they may be drained with an 18-gauge needle inserted into the lateral blister skin. For cutaneous procedures, electrosurgery can be categorized into six different treatment modalities: (1) electrofulguration, (2) electrodesiccation, (3) electrocoagulation, (4) electrosection, (5) electrocautery, and (6) electrolysis. As previously described, pigmented cells are sensitive at temperatures of ­4°C to ­7°C (24. Although pigmentation changes are usually transient, prolonged freezing greater than 30 seconds may result in permanent pigment loss. Topical steroids, glycolic acids, retinoids, and hydroquinone may aid in reducing the incidence of hypopigmentation. This modality is the least tissue damaging of all of the high-frequency electrosurgery techniques, resulting in rapid tissue healing. Therefore, most benign and premalignant lesions treated with cryotherapy heal with little scarring. Scars due to second intention may occur after malignancies treated with cryosurgery. Superficial tissue damage occurs as heat is transferred to tissue, causing cell death. The extent of tissue damage is directly related to electrode contact time with the skin. Although skin injury is greater with electrodesiccation compared to electrofulguration, most of the tissue damage remains superficial. Clinically suspicious actinic keratoses not responsive to cryosurgery should be biopsied to rule out invasive Squamous Cell Carcinoma. Tissue damage is deeper than with electrofulguration and electrodesiccation, providing tissue coagulation through the generation of heat in the tissue. Another distinguishing feature of electrocoagulation is the involvement of the patient within the circuit. This allows the use of a lower voltage and higher amperage to generate more coagulation. Edema, vesicles, bullae, and weeping should be expected from treated areas within 24 hours post-treatment. Treated sites may be rinsed with soap and water and patted dry with a towel daily. The "Bovie" knife incorporates a blended undamped and damped sine wave that provides both cutting and coagulation at the same time. Heat is transferred from the filament to the target tissue, causing protein denaturation and tissue coagulation. There is no electric current transfer to the target tissue, and the patient is not part of the circuit loop. In addition, because patients are not part of the circuit loop, electrocautery is useful for nonconductive tissue areas of the body, such as the cartilage, bone, and nails. Place the dispersing electrode in a location that directs the current pathway away from the cardiac device. Use a bipolar forcep device to maintain the electrical circuit between the forcep tips. Do not discharge the electrosurgical electrode on the skin directly over the pacemaker power source. The negative electrode is applied to the target tissue where electrons are released. The electrons interact with the tissue to produce sodium hydroxide and hydrogen gas resulting in tissue liquefaction. The dispersing electrode (grounding pad) should be placed in a location that directs the current pathway away from the cardiac device (usually the right lower leg). High-frequency electrosurgery may interfere with their function or damage the pacemaker or defibrillator, resulting in patient morbidity or mortality. In direct current, electrons flow in one direction, while in alternating current, electron flow reverses direction. With the exception of electrocautery or electrolysis, electrosurgical units used in dermatologic procedures have high-frequency alternating current. The terms monopolar and bipolar refer to the number of tissue-containing tips at the end of a surgical electrode. Monoterminal refers to the use of a treatment electrode without an indifferent or dispersing electrode. First, the area around the lesion is anesthetized with lidocainecontaining epinephrine. Then, the lesion is touched with the low-power electrode until a gray, superficial charred layer involves the entire lesion. The charred tissue is removed from the treated lesion by wiping with a sterile gauze or curetting. The process is repeated until the lesion is removed at the level of the surrounding skin. This method results in minimal bleeding and scarring because just the epidermal components are removed. Different techniques of electrosurgery can be used based on the type of electrosurgical unit used during surgical procedures. Coagulation can be achieved using electrofulguration electrodesiccation or electrocoagulation by direct application of the electrode to the bleeding vessel. Alternatively, vessels can be grasped by a forcep or hemostat, followed by application of the active electrode. When electrical current is placed against the metal instrument, heat is transferred from the electrode through the metal tip to the vessel. This technique is best used when the surgical field cannot be visualized due to bleeding. Certain tumor characteristics, however, should be present to ensure high cure rates and acceptable cosmetic outcome. Tumors should be primary, have distinct clinical borders, be located on sites of low recurrence such as the trunk, extremities, or non-"H"-zone regions of the face (see Chapters 114 and 115), have a superficial or nodular histologic subtype, and have a diameter of <1 cm on the face and <2 cm on the trunk and extremities. In addition, C+D is a viable treatment option for patients with high morbidity cofactors that make surgical excision too risky or patients who cannot make regular follow-up visits. Tumors not acceptable for C+D include those with indistinct borders, tumors on the "H"-zone of the face, tumors with an aggressive histologic pattern, tumors with high metastatic potential, and tumors that require histologic diagnosis. The tumor outline should be marked, and lidocaine with epinephrine should be injected to provide adequate local anesthesia. Furthermore, the cosmetic result may show hypopigmentation, atrophy, persistent erythema, and hypertrophic scarring. Some authors have speculated that the inflammatory response or a specific antitumor humoral response following electrosurgery may be responsible for the low recurrence rate. In that study, 32 of 34 (94%) lesions demonstrated no residual histological evidence of tumor. This is followed by electrodesiccation on high power of the base and periphery of the lesion. This C+D procedure is repeated up to two more times until a resultant atrophic defect without clinical evidence of residual tumor is achieved. Some advocate the inclusion of a 2- to 4-mm rim of clinically normal skin during the C+D procedure, and individual variations of the protocol are established. The advantages of treatment with C+D include time efficiency, ease of surgical technique, and minimal post-treatment morbidity. Thermal injury can occur if there is inadequate contact between the patient and the dispersing electrode plate, when there is inadvertent contact between the dispersing electrode and the patient or surgeon, and if the patient or surgeon may "ground" him- or herself by touching a metal component of the table. When prepping the patient before electrosurgery, nonflammable disinfectants such as iodine or chlorhexidine should be used. If an alcohol-based disinfectant is used, the surgical area must be allowed to dry for at least 90 seconds prior to electrosurgery. Finally, care should be taken not to ignite paper surgical drapes in the surgical field. This traveling plume has been shown to contain carbonized tissue and blood, airborne particles, and various chemicals and gases. In addition, smoke created from treating lesions such as warts may contain infectious material, such as bacteria and viruses that may transmit infection. The Occupational Safety and Health Administration recommends that surgical smoke be removed and properly filtered by a smoke evacuation system as close to the surgical site as possible. Petroleum jelly and bandage is changed daily after rinsing, for 3­4 weeks or until healed. Complications are best avoided by Obtaining patient history of medications, prior bleeding episodes, allergies, and prior surgeries. Medications such as anticoagulants, pain medications, and certain herbs can affect bleeding at the time of surgery (Table 247-1).

Such cataracts may also be acquired in infantile stage and follow contact of the lens capsule with the back of cornea medications and mothers milk 2014 lquin 250 mg sale, usually after perforation due to ophthalmia neonatorum or any other cause medicine pacifier lquin 250mg without prescription. Morphological types Anterior polar cataracts may occur as any of the following morphological patterns: · Thickenedwhiteplaquein the centre of anterior capsule medicine of the future purchase generic lquin line. In this the thickened capsular opacity is cone-shaped with its apex towards cornea symptoms ms cheap 250 mg lquin free shipping. Environmentalformis associated with: · vitamin D deficiency symptoms stomach cancer cheap lquin 250mg with mastercard, · hypocalcemia · sometimes maternal rubella infection contracted between 7th and 8th week of gestation may also cause lamellar cataract. The main mass of the lens internal and external to the zone of cataract is clear, except for small linear opacities like spokes of a wheel (riders) which may be seen towards the equator. Sutural and axial cataracts Sutural cataracts are comparatively of common · Reduplicated cataract (double cataract). Posterior polar cataract It is a very common lens anomaly and consists of a small circular circumscribed opacity involving the posterior pole. Posterior polar cataract occurs in two forms: · Stationary form and · Progressive form which progresses after birth. Cataracta centralis pulverulenta Cataracta centralis pulverulentais anembryonic nuclear cataract. It has dominant genetic trait and occurs due to inhibition of the lens development at a very early stage and thus, involves the embryonic nucleus. Lamellar cataract occurrence and consist of a series of punctate Lamellar or Z onular cataract refer to the developmental cataract in which the opacity occupies a discrete zone in the lens. The individual opacities vary in size and shape and have different pattern and thus are named accordingly as under: · Floriformcataract. The lenticular opacities are in the form of scattered heaps of shining crystalline needles. It usually involves the Diseases of Lens 185 A B embryonic and fetal nucleus and sometimes infantile nucleus as well. The opacities are often many hundreds in number and have a regular radial distribution in the periphery of lens (corona of clubshaped opacities) encircling the central axis. Total congenital cataract It is a common variety and may be unilateral or bilateral. Therefore, removal of such a cataract is usually followed by a severe inflammatory reaction (uveitis or even endophthalmitis) probably due to liberation of retained viruses. Since, the rubella vaccine is toxic to foetus, it must therefore, be administered atleast three months before the pregnancy. Congenital cataract, salt and pepper chorioretinopathy, microphthalmos, cloudy cornea and poorly dilating pupil. Congenital membranous cataract Sometimes there may occur total or partial absorption of congenital cataract, leaving behind thin membranous cataract. Rarely, there is complete disappearance of all the lens fibres and only a fine transparent lens capsule remains behind. It should aim at knowing the prognostic factors and indications and timing of surgery. Density is indicated by quality of red reflex seen on distant direct ophthalmoscopy before and after dilation of pupil. Laboratory investigations should be carried out to detect following systemic associations in nonhereditary cataracts: Intrauterineinfectionsviz. Galactosemiaby urine test for reducing substances, red blood cell transferase and galacto kinase levels. Prognostic factors Prognostic factors which need to be noted are: · Density of cataract, · Unilateral or bilateral cataract, · Time of presentation, · Associated ocular defects, and · Associated systemic defects C. Bilateraldensecataractsshould be removed early (within 6 weeks of birth) to prevent stimulus deprivation amblyopia. Unilateral dense cataract should preferably be removed as early as possible (within days) after birth with optical correction in the first few weeks. However, it must be born in mind that visual prognosis in most of the unilateral cases is very poor even after timely operation, because correction of aphakia and prevention of amblyopia in infants is an uphill task. Surgical procedures Diseases of Lens 187 Childhood cataracts (congenital, developmental as well as acquired) can be dealt with extra capsular cataract extraction technique involving anterior capsulorrhexis and irrigation aspiration of the lens matter (lens aspiration) or lensectomy. Lens aspiration should be combined with primary posterior capsulotomy in children below 6 years of age and also with anterior vitrectomy in all children below 2 years of age. The needlingoperation(which was performed in the past) is now obsolete because of high rates of complications. In children between 2­8years of age 10% undercorrection and below 2 years an undercorrection by 20% is recommended from the calculated biometric power to counter the myopic shift. Correction of amblyopia It is the central theme around which management of childhood cataract and aphakia revolves. In spite of best efforts, it continues to be the main cause of ultimate low vision in these children. Morphologically, the senile cataract occurs in two forms, the cortical (soft cataract) and the nuclear (hard cataract). It is very common to find nuclear and cortical senile cataracts co-existing in the same eye; and for this reason it is difficult to give an accurate assessment of their relative frequency. In general, the predominant form can be given as cuneiform 70%, nuclear 25% and posterior subcapsular (cupuliform) 5%. Presently, common views are as follows: · Childrenabovetheageof2yearscan be corrected by implantation of posterior chamber intraocular lens during surgery. Present trend is to do primary implantation at the earliest possible specially in unilateral cataract i. Though its precise etiopathogenesis is not clear, the various factors implicated are as follows: 188 A. Concept of syn- and co-cataractogenic factors Risk factors affecting age of onset, type and maturation of senile cataract are as below: 1. However, in many studies it is reported that prevalence of cataract is greater in females than males at all ages. It plays a considerable role in the incidence, age of onset and maturation of senile cataract in different families. Diet deficient in certain proteins, amino acids, vitamins (riboflavin, vitamin E, vitamin C), and essential elements have also been blamed for early onset and maturation of senile cataract. An association with prior episode of severe dehydrational crisis (due to diarrhoea, cholera, etc. Smoking has also been reported to have some effect on the age of onset of senile cataract. In numerous studies worldwide smoking has consistently been associated with an increase in the frequency of nuclear cataract. Smoking causes accumulation of pigmented molecules-3-hydroxykynurenine and chromophores, which lead to yellowing. Causes of pre-senile cataract It has been conceptualised that cataract is the result of multiple subthreshold cataractogenic stresses acting in a concert. Age has been implicated as one of these cataractogenic stresses and that superimposition of other toxic stresses on the ageing lens may accelerate the rate of cataract formation. Conversely, the elimination of one or more cataractogenic stresses may delay the cataract formation. Mechanism of loss of transparency It is basically different in nuclear and cortical senile cataracts. Its main biochemical features are decreased levels in the crystalline lens of total proteins, amino acids and potassium associated with increased concentration of sodium and marked hydration of the lens, followed by coagulation of lens proteins. The probable course of events leading to senile opacification of cortex is as shown in the. In this the usual degenerative changes are intensification of the age-related nuclear sclerosis associated with dehydration and compaction of the nucleus resulting in a hard cataract. There may or may not be associated deposition of pigment urochrome and/or melanin derived from amino acids in the lens. The term pre-senile cataract is used when the cataractous changes similar to senile cataract occur before 50 years of age. Myotonicdystrophyis associated with posterior subcapsular type of pre-senile cataract. In this stage, change is demarcation of cortical fibres owing to their separation by fluid. Two distinct types of senile cortical cataracts can be recognised at this stage: a. On distant direct ophthalmoscopy, these opacities appear as dark lines against the red fundal glow. Since the cuneiform cataract starts at periphery and extends centrally, the visual disturbances are noted at a comparatively late stage. Here a saucer-shaped opacity develops just below the capsule usually in the central part of posterior cortex (posterior subcapsular cataract), which gradually extends outwards. There is usually a definite demarcation between the cataract and the surrounding clear cortex. In some patients, at this stage, lens may become swollen due to continued hydration. Due to shrinkage of lens, anterior chamber becomes deep and iris becomes tremulous (iridodonesis). The small brownish nucleus settles at the bottom, altering its position with change in the position of the head. Sometimes after the stage of maturity, the cortex becomes disintegrated and the lens becomes shrunken due to leakage of water. The anterior capsule is wrinkled and thickened due to proliferation Progressive nuclear sclerotic process renders the lens inelastic and hard, decreases its ability to accommodate and obstructs the light rays. In practice, the commonly observed pigmented nuclear cataracts are either amber, brown (cataractabrunescens)or black (cataractanigra)and rarely reddish (cataractarubra)in colour. These patients see better when pupil is dilated due to dim light in the evening (day blindness). Diseases of Lens 191 Such patients may be able to read without presbyopic glasses. As opacification progresses, vision steadily diminishes, until only perception of light and accurate projectionoflightraysremains in the stage of mature cataract. Following examination should be carried out to look for different signs of cataract shown in Table 9. It reveals colour of the lens in papillary area which varies in different types of cataracts (Table 9. When an oblique beam of light is thrown on the pupil, a crescentric shadow of pupillary margin of the iris will be formed on the greyish opacity of the lens, as long as clear cortex is present between the opacity and the pupillary margin. A reddish yellow fundal glow is observed in the absence of any opacity in the media. Iris shadow Seen Multiple dark areas against red fundal glow Areas of normal with cataractous cortex Not seen No red glow milky white pupil Milky white cortex with sunken brownish nucleus 4. Distant direct Central dark ophthalmoscopy area against red with dilated fundal glow pupil 5. Gradingofnucleus hardnessin a cataractous lens is important for setting the parameters of machine in phacoemulsification technique of cataract extraction. The hardness of the nucleus, depending upon its colour on slit-lamp examination, can be graded as shown in Table 9. Greyish colour of lens from the nuclear sclerosis without any cataract as shown in Table 9. Mature senile cataract can be differentiated from retrolental causes of white pupillary reflex (leukocoria) as shown in Table 9. No black spots are seen against red glow leak into the anterior chamber in hypermature Table 9. These proteins may act as antigen and induce antigen-antibody reaction leading to phacoanaphylactic uveitis. Slit-lamp examination shows cataractous lens Leukocoria (due to retrolental causes) 1. Slit-lamp examination shows transparent lens with white reflex behind the lens Diseases of Lens 193. Ultrasonography reveals opacity in the vitreous cavity secondary angle closure glaucoma. Lens proteins are leaked into the anterior chamber in cases with Morgagnian type hypermature cataract. Thus, the phacolytic glaucoma is a type of secondary open angle glaucoma (for details see page 248). Hypermature cataractous lens may subluxate/dislocate and cause glaucoma by blocking the pupil or angle of anterior chamber. Initially, a large number of fluid vacuoles appear underneath the anterior and posterior capsules, which is soon followed by appearance of bilateral snowflake-like white opacities in the cortex. Galactosaemic cataract It is associated with inborn error of galactose metabolism. Galactosaemia is frequently associated with the development of bilateral cataract (oil droplet central lens opacities). Hypocalcaemic (Tetanic) cataract Diabetes is associated with two types of cataracts: 1. It is a rare condition, usually occurring in young adults due to osmotic over hydration of the lens. Multicolouredcrystals or small discrete white flecks of opacities are formed in the cortex which seldom mature. Zonularcataract, characterized by a thin opacified lamella deep in the infantile cortex is typically seen in infants with hypocalcemia. Degenerativeconditionssuch as retinitis pigmentosa and other pigmentary retinal dystrophies and myopic chorioretinal degeneration. Intraoculartumourssuch as retinoblastoma or melanoma may give rise to complicated cataract in late stages.

Ingestion of more than 1 g of a tricyclic (or about 15­20 mg/kg) is considered potentially lethal medicine man movie purchase lquin online now. Poisoning causes uncoupling of oxidative phosphorylation and disruption of normal cellular metabolism symptoms 22 weeks pregnant 250 mg lquin order free shipping. Arterial blood gas testing often reveals a mixed respiratory alkalosis and metabolic acidosis symptoms gastritis lquin 250mg purchase free shipping. Vomiting and hyperpnea as well as hyperthermia contribute to fluid loss and dehydration medications in carry on cheap lquin generic. Absorption of salicylate and signs of toxicity may be delayed after very large overdoses or ingestion of enteric coated tablets medicine joji discount lquin 250 mg fast delivery. After massive aspirin ingestions (eg, more than 100 tablets), aggressive gut decontamination is advisable, including gastric lavage, repeated doses of activated charcoal, and consideration of whole bowel irrigation. For moderate intoxications, intravenous sodium bicarbonate is given to alkalinize the urine and promote salicylate excretion by trapping the salicylate in its ionized, polar form. For severe poisoning (eg, patients with severe acidosis, coma, and serum salicylate level >90­100 mg/dL), emergency hemodialysis is performed to remove the salicylate more quickly and restore acid-base balance and fluid status. Since most ingested calcium antagonists are in sustained-release form, it may be possible to expel them before they are completely absorbed; initiate whole bowel irrigation and oral activated charcoal as soon as possible, before calcium antagonist-induced ileus intervenes. Calcium, given intravenously in doses of 2­10 g, is a useful antidote for depressed cardiac contractility but less effective for nodal block or peripheral vascular collapse. Other treatments reported to be helpful in managing hypotension associated with calcium channel blocker poisoning include highdose insulin (0. A few case reports have suggested benefit from administration of lipid emulsion (normally used as an intravenous dietary fat supplement) for severe verapamil overdose. Many other toxic gases are produced in fires or released in industrial accidents (Table 58­4). It can improve heart rate and blood pressure when given in high doses (5­20 mg intravenously). Most cases of serious organophosphate or carbamate poisoning result from intentional ingestion by a suicidal person, but poisoning has also occurred at work (pesticide application or packaging) or, rarely, as a result of food contamination or terrorist attack (eg, release of the chemical warfare nerve agent sarin in the Tokyo subway system in 1995). Stimulation of nicotinic receptors causes generalized ganglionic activation, which can lead to hypertension and either tachycardia or bradycardia. Gas Irritant gases (eg, chlorine, ammonia, sulfur dioxide, nitrogen oxides) Carbon monoxide Cyanide Mechanism of Toxicity Corrosive effect on upper and lower airways Binds to hemoglobin, reducing oxygen delivery to tissues Binds to cytochrome, blocks cellular oxygen use Clinical Features and Treatment Cough, stridor, wheezing, pneumonia Treatment: Humidified oxygen, bronchodilators Headache, dizziness, nausea, vomiting, seizures, coma Treatment: 100% oxygen; consider hyperbaric oxygen Headache, nausea, vomiting, syncope, seizures, coma Treatment: Conventional antidote kit consists of nitrites to induce methemoglobinemia (which binds cyanide) and thiosulfate (which hastens conversion of cyanide to less toxic thiocyanate); a newer antidote kit (Cyanokit) consists of concentrated hydroxocobalamin, which directly converts cyanide into cyanocobalamin Similar to cyanide. Smell of rotten eggs Treatment: No specific antidote; some authorities recommend the nitrite portion of the conventional cyanide antidote kit. Oxidizing agents (eg, nitrogen oxides) Can cause methemoglobinemia Dyspnea, cyanosis (due to brown color of methemoglobin), syncope, seizures, coma Treatment: Methylene blue (which hastens conversion back to normal hemoglobin) Hydrogen sulfide Similar to cyanide plasma (butyrylcholinesterase) enzymes, which provide an indirect estimate of synaptic cholinesterase activity. This is especially critical for the most potent substances such as parathion or nerve gas agents. Atropine is an effective competitive inhibitor at muscarinic sites but has no effect at nicotinic sites. Pralidoxime given early enough may be capable of restoring the cholinesterase activity and is active at both muscarinic and nicotinic sites; however, studies are conflicting regarding its effect on clinical outcome. Patients receiving long-term digoxin treatment are often also taking diuretics, which can lead to electrolyte depletion (especially potassium). Hyperkalemia may be caused by acute digitalis overdose or severe poisoning, whereas hypokalemia may be present in patients as a result of long-term diuretic treatment. Cyanide binds readily to cytochrome oxidase, inhibiting oxygen utilization within the cell and leading to cellular hypoxia and lactic acidosis. Symptoms of cyanide poisoning include shortness of breath, agitation, and tachycardia followed by seizures, coma, hypotension, and death. Poisoning with other metals (lead, mercury, arsenic) is also important, especially in industry. Ethanol blood levels greater than 300 mg/dL usually cause deep coma, but regular users are often tolerant to the effects of ethanol and may be ambulatory despite even higher levels. Hypotension usually responds to intravenous fluids, body warming if cold, and, if needed, dopamine. Systemic effects include nausea, vomiting, muscle fasciculations, tingling and metallic taste in the mouth, shock, and systemic coagulopathy with prolonged clotting time and reduced platelet count. Definitive therapy relies on intravenous antivenom (also known as antivenin), and this should be started as soon as possible. In addition, their products of metabolism-formic acid (from methanol) or hippuric, oxalic, and glycolic acids (from ethylene glycol)-cause a severe metabolic acidosis and can lead to coma and blindness (in the case of formic acid) or renal failure (from oxalic acid and glycolic acid). Patients with methanol poisoning may have visual disturbances ranging from blurred vision to blindness. Caffeine produces similar toxic effects and it is available in several "energy" supplements. Cardiac arrhythmias include atrial tachycardias, premature ventricular contractions, and ventricular tachycardia. In severe poisoning (eg, acute overdose with serum level >100 mg/L), seizures often occur and are usually resistant to common anticonvulsants. Toxicity may be delayed in onset for many hours after ingestion of sustained-release tablet formulations. Propranolol or other blockers (eg, esmolol) are useful antidotes for -mediated hypotension and tachycardia. Phenobarbital is preferred over phenytoin for convulsions; most anticonvulsants are ineffective. Hemodialysis is indicated for serum concentrations >100 mg/L and for intractable seizures in patients with lower levels. If this is not effective, phenobarbital or another more potent central nervous system depressant may be used. Lipid Solubility As is true also of other biologic membranes, drug passage across the placenta is dependent on lipid solubility and the degree of drug ionization. Lipophilic drugs tend to diffuse readily across the placenta and enter the fetal circulation. If high enough maternal-fetal concentration gradients are achieved, polar compounds cross the placenta in measurable amounts. Molecular Size and pH the molecular weight of the drug also influences the rate of transfer and the amount of drug transferred across the placenta. Drugs with molecular weights of 250­500 can cross the placenta easily, depending upon their lipid solubility and degree of ionization; 1047 the effects of drugs on the fetus and newborn infant are based on the general principles set forth in Chapters 1­4 of this book. However, the physiologic contexts in which these pharmacologic laws operate are different in pregnant women and in rapidly maturing infants. Critical factors affecting placental drug transfer and drug effects on the fetus include the following: (1) the physicochemical properties of the drug; (2) the rate at which the drug crosses the placenta and the amount of drug reaching the fetus; (3) the duration of exposure to the drug; (4) distribution characteristics in different fetal tissues; (5) the stage of placental and fetal development at the time of exposure to the drug; and (6) the effects of drugs used in combination. Starting in the second trimester of pregnancy, the placenta develops transporters that allow immunoglobulins to cross from the mother to the fetus despite their large molecular size. This has important clinical implications, because an increasing number of biological drugs (eg, anti-tumor necrosis factor therapy) have been shown to cross the placenta. With an increasing number of infants exposed to immunoglobulin biologicals in utero, there is a need to address the challenges in vaccinating these infants. Placental Transporters During the last decade, many drug transporters have been identified in the placenta, with increasing recognition of their effects on drug transfer to the fetus. The hypoglycemic drug glyburide has lower plasma levels in the fetus as compared with the mother. However, if a compound is very lipid-soluble (eg, some anesthetic gases), it will not be affected greatly by protein binding. This is because very lipid-soluble drugs diffuse across placental membranes so rapidly that their overall rates of equilibration do not depend on the free drug concentrations becoming equal on both sides. This has been shown for sulfonamides, barbiturates, phenytoin, and local anesthetic agents. Drugs that have crossed the placenta enter the fetal circulation via the umbilical vein. About 40­60% of umbilical venous blood flow enters the fetal liver; the remainder bypasses the liver and enters the general fetal circulation. A drug that enters the liver may be partially metabolized there before it enters the fetal circulation. Maternal Drug Actions the effects of drugs on the reproductive tissues (breast, uterus, etc) of the pregnant woman are sometimes altered by the endocrine environment appropriate for the stage of pregnancy. For example, cardiac glycosides and diuretics may be needed for heart failure precipitated by the increased cardiac workload of pregnancy, or insulin may be required for control of blood glucose in pregnancy-induced diabetes. This involves drug administration, mostly to the pregnant woman, with the fetus as the target of the drug. At present, corticosteroids are used to stimulate fetal lung maturation when preterm birth is expected. Although their efficacy has not yet been established by controlled studies, digoxin, flecainide, procainamide, verapamil, and other antiarrhythmic agents have been shown to be effective in case series. Predictable Toxic Drug Actions in the Fetus Chronic use of opioids by the mother often produces dependence in the fetus and newborn. This dependence may be manifested after delivery as a neonatal withdrawal syndrome. A less well understood fetal drug toxicity is caused by the use of angiotensinconverting enzyme inhibitors during late pregnancy. These drugs can result in significant and irreversible renal damage in the fetus and are therefore contraindicated in pregnant women. Teratogenic Drug Actions A single intrauterine exposure to a drug can affect the fetal structures undergoing rapid development at the time of exposure. This exposure, however, must be at a critical time in the development of the limbs. For example, drugs may have a direct effect on maternal tissues with secondary or indirect effects on fetal tissues. Finally, deficiency of a critical substance appears to play a role in some types of abnormalities. For example, folic acid supplementation during pregnancy appears to reduce the incidence of neural tube defects (see Box, page 599). Continued exposure to a teratogen may produce cumulative effects or may affect several organs going through varying stages of development. Chronic consumption of high doses of ethanol during pregnancy, particularly during the first and second trimesters, may result in the fetal alcohol spectrum disorder (see Chapter 23). In this syndrome, the central nervous system, growth, and facial development may be affected. Teratogenic effects are not limited only to major malformations, but also include intrauterine growth restriction (eg, cigarette smoking), miscarriage (eg, alcohol), stillbirth (eg, cigarette smoke), and neurocognitive delay (eg, alcohol, valproic acid). In addition to teratogenic drugs, teratogenicity can be induced by a large group of infectious pathogens, including viruses such as rubella, cytomegalovirus, herpes, and recently, Zika virus. Similarly, numerous chemicals, such as heavy metals (eg, mercury, lead) and environmental factors (eg, radiation, hyperthermia) can damage the fetus. It is important to consider these nondrug factors in the differential diagnosis of drug-induced adverse fetal effects. The ability of appropriate counseling to prevent unnecessary abortions has been documented. It is also critical to address the maternal-fetal risks of the untreated condition if a medication is avoided. Recent studies show serious morbidity in women who discontinued selective serotonin reuptake inhibitor therapy for depression in pregnancy. Pharmacodynamic differences between pediatric and other patients have not been explored in great detail but are probably important for those specific target tissues that mature at birth or immediately thereafter (eg, the ductus arteriosus). Unique factors that influence drug absorption include blood flow at the site of administration, as determined by the physiologic status of the infant or child; and, for orally administered drugs, gastrointestinal function, which changes rapidly during the first few days after birth. However, sick preterm infants requiring intramuscular injections may have very little muscle mass. In such cases, absorption becomes irregular and difficult to predict, because the drug may remain in the muscle and be absorbed more slowly than expected. If perfusion suddenly improves, there can be a sudden and unpredictable increase in the amount of drug entering the circulation, resulting in high and potentially toxic concentrations of drug. Examples of drugs especially hazardous in such situations are cardiac glycosides, aminoglycoside antibiotics, and anticonvulsants. Gastrointestinal Function Significant biochemical and physiologic changes occur in the neonatal gastrointestinal tract shortly after birth. Either animal-reproduction studies have not demonstrated a fetal risk, but there are no controlled studies in pregnant women, or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the first trimester (and there is no evidence of a risk in later trimesters). C D X 1 this system has been changed as of 2014 by eliminating the A, B, C qualifications and replacing them with specific structured narratives for each drug. Therefore, drugs that are absorbed primarily in the stomach may be absorbed more completely than anticipated. The fraction of drug absorbed in the small intestine may therefore be unpredictable; more than the usual amount of drug may be absorbed if peristalsis is slowed, and this could result in toxicity from an otherwise standard dose. An increase in peristalsis, as in diarrheal conditions, tends to decrease the extent of absorption, because contact time with the large absorptive surface of the intestine is decreased. Neonates also have low concentrations of bile acids and lipase, which may decrease the absorption of lipidsoluble drugs. Differences can also be observed between the full-term neonate (70% of body weight as water) and the small preterm neonate (85% of body weight as water). Total body fat in preterm infants is about 1% of total body weight, compared with 15% in full-term neonates. Therefore, organs that generally accumulate high concentrations of lipid-soluble drugs in adults and older children may accumulate smaller amounts of these agents in less mature infants. Another major factor determining drug distribution is drug binding to plasma proteins. In general, protein binding of drugs is reduced in the neonate, as seen with local anesthetic drugs, diazepam, phenytoin, ampicillin, and phenobarbital. Therefore, the concentration of free (unbound) drug in plasma is increased initially.

Examples include systemic lupus erythematosus following hydralazine or procainamide therapy treatment yeast infection home cheap lquin 250mg otc, "lupoid hepatitis" due to cathartic sensitivity silent treatment discount lquin 250 mg with amex, autoimmune hemolytic anemia resulting from methyldopa administration medicine z pack discount lquin uk, thrombocytopenic purpura due to quinidine medicine 4212 lquin 250 mg order, and agranulocytosis due to a variety of drugs symptoms 9 days post ovulation cheap lquin 250mg without prescription. In these drug-induced autoimmune states, IgG antibodies bind to drug-modified tissue and are destroyed by the complement system or by phagocytic cells with Fc receptors. Immunosuppressive therapy is warranted only when the autoimmune response is unusually severe. Drugs that modify allergic responses act at several links in this chain of events. Epinephrine opposes histamine; it relaxes bronchiolar smooth muscle and contracts vascular muscle, relieving both bronchospasm and hypotension. As noted in Chapter 8, epinephrine is the drug of choice in anaphylactic reactions. The antihistamines competitively inhibit histamine, which would otherwise produce bronchoconstriction and increased capillary permeability in end organs. The mechanism of tissue injury is immune complex formation and deposition on basement membranes (eg, lung, kidney), followed by complement activation and infiltration of leukocytes, causing tissue destruction. The sulfonamides, penicillin, thiouracil, anticonvulsants, and iodides all have been implicated in the initiation of hypersensitivity angiitis. Stevens-Johnson syndrome is probably a more severe form of this hypersensitivity reaction and consists of erythema multiforme, arthritis, nephritis, central nervous system abnormalities, and myocarditis. Like other drug hypersensitivities, the drug may chemically react with host tissue to create a new antigen. Upon first exposure to the allergen (drug), antigen-presenting cells stimulate a T-cell response specific for that allergen. Upon second and all subsequent exposures, tissue-derived antigen-presenting cells that come in contact with the new antigen (allergen-modified host protein) secrete chemokines and cytokines that attract memory T cells to the site of allergen re-exposure. Lymphocytes and antigen-presenting cells such as macrophages accumulate at the site, causing induration, erythema, and swelling. Immunosuppressive Agents Capron A et al: Intra-cellular immunosuppressive drug monitoring: A step forward towards better therapeutic efficacy after organ transplantation Wolf M et al: Peripheral administration of antithymocyte globulins: A review of current literature. Rheumatology 2016;55:775 Cantini F et al: Tailored first-line biologic therapy in patient with rheumatoid arthritis, spondyloarthritis, and psoriatic arthritis. Macy E: Practical management of patients with a history of immediate hypersensitivity to common non-beta-lactam drugs. Immunodeficiency Diseases Sriaroon P, Ballow M: Immunoglobulin replacement therapy for primary immunodeficiency. Acute graft-vs-host disease is the process of donor T cells attacking host recipient tissues (including skin), despite ongoing immunosuppressive therapy such as tacrolimus. She is comatose, tachypneic (25 breaths per minute), and tachycardic (150 bpm), but she appears flushed, and fingertip pulse oximetry is normal (97%) breathing room air. Questioning of her parents reveals that they are homeless and have been living in their car (a small van). The nights have been cold, and they have used a small charcoal burner to keep warm inside the vehicle. The occupational-environmental toxicologist is primarily concerned with adverse effects in humans resulting from exposure to chemicals encountered at work or in the general environment. In clinical practice, the occupational-environmental toxicologist must identify and treat the adverse health effects of these * the author thanks the late Gabriel L. Occupational and environmental toxicology cases present unusually complex problems. Occupational and environmental exposure is rarely limited to a single type of molecule. Because many of these illnesses have long latency periods before they become manifest, it is often a matter of detective work, when patients finally present with disease, to ascertain past exposure and relate it to present clinical effect. Air pollution is usually a product of industrialization, technologic development, and increased urbanization. Tables of primary and secondary regulated air contaminants and other regulatory issues that relate to air contaminants in the United States may be found at. In the case of adjoining countries, transborder air and water pollution problems have been of concern in recent years. This type of pollution is now the subject of much research and of new international treaties. Major international problems have occurred because of traffic among nations in contaminated or adulterated foods from countries whose regulations and enforcement of pure Occupational Toxicology Occupational toxicology deals with the chemicals found in the workplace. Occupational toxicologists may also define and carry out programs for the surveillance of exposed workers and the environment in which they work. They frequently work hand in hand with occupational hygienists, certified safety professionals, and occupational health nurses in their activities. Regulatory limits and voluntary guidelines have been elaborated to establish safe ambient air concentrations for many chemicals found in the workplace. Governmental and supragovernmental bodies throughout the world have generated workplace health and safety rules, including short- and long-term exposure limits for workers. These standards are developed following extensive scientific study, stakeholder input at hearings, public comment, and other steps such as publication in the Federal Register. Such standards have the force of law and employers who use these materials are obligated to comply with the standards. Regulatory imperatives in the United States may also be updated from time to time when new information about toxicity becomes available. Ecotoxicology research has become one of the foremost areas of study for toxicologists. Risk is defined as the expected frequency of the occurrence of an undesirable effect arising from exposure to a chemical or physical agent. The quality and suitability of the biologic data used in such estimates are major limiting factors. Risk assessment has become an integral part of the regulatory process in most countries. However, many of the assumptions of risk assessment scientists remain unproven, and only long-term observation of population causes and outcomes will provide the basis for validation of newer risk assessment technologies. Acute exposure indicates a single exposure or multiple exposures that occur over a brief period from seconds to 1­2 days. The same amount of the substance, absorbed slowly, may result in little or no toxicity. Rhodanese, a mitochondrial enzyme present in humans, effectively detoxifies cyanide to relatively nontoxic thiocyanate when cyanide is presented in small amounts, but the enzyme is overwhelmed by large, rapidly encountered cyanide doses, with lethal effect. Single or multiple exposures over a longer period of time represent chronic exposure. Exposures to chemicals found in the environment such as air and water pollutants are often chronic, resulting in chronic disease, as in the Minamata Bay, Japan, methyl mercury disaster. The release of dioxin in Seveso, Italy, contaminated a populated area with a persistent organic chemical having both acute and long-term chronic effects. Lipophilic substances such as the largely banned or abandoned organochlorine pesticides tend to bioaccumulate in body fat. These residues and their metabolites may have chronic adverse effects such as endocrine disruption. They may be exposed to highly concentrated pollutant loads as bioaccumulation and biomagnification occur. Water and soil pollutants are absorbed through inhalation, ingestion, and dermal contact. Quantity, Duration, & Intensity of Exposure Toxic reactions may differ depending on the quantity of exposure, its duration, and the rate at which the exposure takes place. Five major substances have been said to account for about 98% of air pollution: carbon monoxide (about 52%); sulfur oxides (about 14%); hydrocarbons (about 14%); nitrogen oxides (about 14%) and ozone, their breakdown product; and particulate matter (about 4%). Agriculture, especially industrial-scale farming, contributes a variety of air pollutants: dusts as particulates, pesticidal chemicals, hydrogen sulfide, and others. Studies in Helsinki and other cities have shown that uncatalyzed automobile traffic emissions are larger contributors to groundlevel air pollution than any other source. The introduction of catalytic converters on automobiles and their mandatory use in many countries has greatly reduced automobile-released air pollution. In emerging economies, the use of transport based on two-cycle engines creates heavy ground-level air pollution in very crowded cities. Sulfur dioxide and smoke from incomplete combustion of coal have been associated with acute adverse effects among children, the elderly, and individuals with preexisting cardiac or respiratory disease. Ambient air pollution has been implicated as a cause of cardiac disease, bronchitis, obstructive ventilatory disease, pulmonary emphysema, bronchial asthma, and airway or lung cancer. Extensive basic science and clinical epidemiologic literature on air pollutant toxicology has been published and has led to modifications of regulatory standards for air pollutants. Ambient air standards for carbon monoxide and five other harmful pollutants-particulate matter, nitrogen dioxide, ozone, sulfur dioxide, and lead-may be found at. Clinical effects and treatment-The signs and symptoms of intoxication include irritation of the eyes, nose, and throat, reflex bronchoconstriction, and increased bronchial secretions. Both also contribute to the respirable fine particulate load and to increased urban cardiorespiratory morbidity and mortality. There is great variability in individual responses to carboxyhemoglobin concentration. Collapse and syncope may appear at around 40%; and with levels above 60%, death may ensue as a result of irreversible damage to the brain and myocardium. Therefore, patients should be treated with high concentrations only for a short period. Miners who are regularly exposed to diesel equipment exhaust have been particularly affected by nitrogen oxide emissions with serious respiratory effects. Inhalation damages the lung infrastructure that produces the surfactant necessary to allow smooth and low-effort lung alveolar expansion. If only type I cells are damaged, after an acute period of severe distress, it is likely that treatment with modern ventilation equipment and medications will result in recovery. In addition to the direct deep lung effect, long-term exposure to lower concentrations of nitrogen dioxide has been linked to cardiovascular disease, increased incidence of stroke, and other chronic disease. Exposure for 1 hour to 50 ppm can cause pulmonary edema and perhaps subacute or chronic pulmonary lesions; 100 ppm can cause pulmonary edema and death. These compounds are produced primarily when fossil fuels such as gasoline, oil, or coal are burned or when some chemicals (eg, solvents) evaporate. Nitrogen oxides are emitted from power plants, motor vehicles, and other sources of high-heat combustion. Volatile organic compounds are emitted from motor vehicles, chemical plants, refineries, factories, gas stations, paint, and other sources. More information on ground-level ozone and its sources and consequences may be found at. There is a near-linear gradient between exposure to ozone (1-hour level, 20­100 ppb) and bronchial smooth muscle response. Mechanism of action and clinical effects-Ozone is an irritant of mucous membranes. Severe exposure can cause deep lung irritation, with pulmonary edema when inhaled at sufficient concentrations. The morphologic and biochemical changes are the result of both direct injury and secondary responses to the initial damage. Long-term exposure in animals results in morphologic and functional pulmonary changes. The substances include carbon tetrachloride, chloroform, trichloroethylene, tetrachloroethylene (perchloroethylene), and 1,1,1-trichloroethane (methyl chloroform). Many halogenated aliphatic hydrocarbons are classified as known or probable human carcinogens. Carbon tetrachloride and trichloroethylene have largely been removed from the workplace. The Canadian Center for Occupational Health and Safety lists occupations and exposures to occupational carcinogens at. Fluorinated aliphatics such as the freons and closely related compounds have also been used in the workplace, in consumer goods, and in stationary and mobile air conditioning systems. Several are also carcinogenic in animals and are considered probable human carcinogens. Chloroform, carbon tetrachloride, trichloroethylene, and tetrachloroethylene carcinogenicity have been observed in lifetime exposure studies performed in rats and mice and in some human epidemiologic studies. It has been widely used as a paint stripper, plastic glue, and for other purposes. Other cancers are increased but their incidence has not reached statistical significance. In cold climates such as Alaska, benzene concentrations in gasoline may reach 5% in order to provide an octane boost. Exposure to concentrations greater than 3000 ppm may cause euphoria, nausea, locomotor problems, and coma. Aplastic anemia, leukopenia, pancytopenia, and thrombocytopenia occur, as does leukemia. Chronic exposure to low levels of benzene has been associated with leukemia of several types as well as lymphomas, myeloma, and myelodysplastic syndrome. The pluripotent bone marrow stem cells appear to be targets of benzene or its metabolites and other stem cells may also be targets. Benzene has long been known to be a potent clastogen, ie, a mutagen that acts by causing chromosomal breakage.

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