System respiratory

The respiratory system is responsible for generating and regulating the transpulmonary pressures needed to inflate and deflate the lung. Normal gas exchange between the lung and blood requires breathing patterns that ensure appropriate alveolar ventilation. Ventilatory disorders that alter alveolar ventilation are defined as hypoventilation or hyperventilation syndromes. Hyperventilation results in an increase in the partial pressure of arterial CO2 above normal limits and can lead to acidosis, pulmonary hypertension, congestive heart failure, headache, and disturbed sleep. Hypoventilation results in a decrease in the partial pressure of arterial CO2 below normal limits and can lead to alkalosis, syncope, epileptic attacks, reduced cardiac output, and muscle weakness. 

Chronic Sulfasalazine Sulfonamides Pentamidine Anti-inflammatory Acetylsalicylic acid  

Angiotensin-converting enzyme inhibitors Anticoagulants Beta blockers  

Typically cause acute or subacute respiratory insufficiency. 

Nebulized pentamidine, beclomefhasone, and propellants Hydrocortisone Cocaine Propafenone 

The effects on the respiratory system (RS) may be a characteristic presentation of toxic trauma and cover a range of seriousness from mild incapacitation to life-threatening cardiorespiratory failure. Because of the problems of the latency of action of many toxic substances, the effects on the RS may be still developing at the time of investigation. Constant re-examination of the systems for signs of deterioration is therefore essential. 

As noted in Chap. 4, toxic trauma to the RS and cardiovascular system (CVS) may occur as a direct effect on the lungs and the respiratory tree and also indirectly due to the effects on the brainstem-controlled breathing. Airways may be blocked by direct action (e.g. sulphur mustard) and by pharmacological actions (e.g. nerve agents). Box 7.4 summarises the presenting signs of toxic agents effects on the airways. 

4 Ways in which toxic agents can affect the airway 

Large-airways secretions and blockage Small-airways bronchospasm, e.g. SO2 Nerve agents 

Colour of skin and mucous membranes evidence of cyanosis or cherry red colour  

About 10% of the U.S. population (more than 30 million people) suffers from chronic lung diseases. Of these, about 12 million experience at least one asthma attack annually. The causes for this respiratory disease epidemic include environmental exposures to chemical as well as biological agents.  

The toxic effects of single chemicals on the respiratory system have been fairly well characterized and are listed in numerous places as described earlier in Section 13.2. Though there is no one list of all respiratory toxins, the Scorecard list contains an extensive list of these and includes references for further investigation. 

The effects of single chemicals on the respiratory system are discussed as background for an understanding of the effects of mixtures. As previously discussed in Section 2.3, unexpected chemical mixture exposure effects are observed when the mixtures contain at least one lipophilic and one hydrophilic chemical. This chapter addresses the effects of chemical mixtures on the respiratory system. Case studies from the literature with widely different mixture combinations are used to illustrate the effects noted. 

Chemicals and chemical mixtures that attack the respiratory system are categorized as corrosives, irritants, and sensitizers. Though the term irritant is often applied in the literature to chemicals that are either corrosives or irritants, the definitions used here are those that follow. These definitions are identical to those used by toxicologists and regulatory agencies to classify the hazards due to chemical inhalation. 

Corrosive. A corrosive chemical is one that causes visible destruction of, or irreversible alterations in, respiratory tract tissue upon inhalation of vapors, mists, or fine particulates by chemical action at the site of contact. For most chemicals, corrosivity is a function of concentration. At sufficiently low concentrations, corrosive chemical vapors may act as irritants. Hydrogen chloride, nitrogen dioxide, and sodium hydroxides are examples of chemicals corrosive to the respiratory system. 

Personal protective equipment is designed to protect an individual when faced with a particular hazardous situation. Accordingly, one must determine the need for such equipment, the type to be used, and the conditions under which it must be worn. For simplicity, we will consider protection under four categories respiratory system face and eyes head and ears body and limbs. 

The respiratory system is particularly vulnerable to a decrease in the oxygen concentration in the atmosphere (Chapter 2). Accordingly, 

Air-line respirators and SCBA units can also be used to enter atmospheres contaminated with fluorine and carbon monoxide. However, full hoods of inert materials such as Teflon or KelF must be used to avoid skin contact with fluorine these materials can also be used to protect the rest of the body. 

As noted in Chapter 2, the minimum allowable oxygen concentration in an oxygen-deficient atmosphere depends on the nature of the diluting gas. Thus, because of the peculiar role of carbon dioxide in the respiratory functions of the body, the oxygen concentration in the atmosphere must not drop below 19 vol. % this corresponds to a carbon dioxide content of 9 vol. % accordingly, air-line respirators and SCBA units must be used with relatively small carbon dioxide concentrations in the air. 

Commercial monitors and alarms are now available to detect the vapors of each of the cryogenic fluids considered here (Chapter 5). Unfortunately, many of these respond too slowly for effective use under gross spill conditions in practice, operating personnel can often detect a hazardous condition before the alarm sounds. There have been 

About 10% of the population of the United States (more than 30 million people, including 10 million children) suffers from chronic lung diseases. Of these, abont 12 million, including over 4 million children, experience at least one asthma attack annually [1, 2], A WHO smdy in Europe, the International Smdy of Asthma and Allergies in Childhood (ISAAC), found that the asthma prevalence in children ranged from less than 5% to greater than 20% [2-4], The results of that smdy are shown in Table 17.1. 

Country Prevalence in 6- to 7-Year-Old Children (%) Prevalence in 13- to 14-Year-Old Children (%) 

The causes for this respiratory disease epidemic include environmental exposures to chemical as well as biological agents [5]. 

Development of the human lung begins in the embryo and continues until the age of 18-20 years. Cellular differentiation and 

Pores of Kohn are collateral connections between air spaces through which infections can spread. 

Micro caseating granulomas with acid-fast bacilli Lab positive skin test (PPD) 

Most lesions(95%) will undergo fibrosis and calcification Secondary pulmonary tuberculosis 

Simon focus granuloma at lung apex (high oxygen tension) Progressive pulmonary tuberculosis 

Prognosis favorable with a variable clinical course D. Obstructive versus Restrictive Lung Disease 

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Selenium is an essential element and is beneficial at low concentrations, serving as an antioxidant. Lack of selenium affects thyroid function, and selenium deficiencies have been linked to Keshan Disease (34). Selenium at high levels, however, is toxic. Hydrogen selenide (which is used in semiconductor manufacturing) is extremely toxic, affecting the mucous membranes and respiratory system. However, the toxicity of most organ oselenium compounds used as donor compounds for organic semiconductors is not weU studied. 

The use of metered-dose valves in aerosol medical appHcations permits an exact dosage of an active dmg to be deHvered to the respiratory system where it can act locally or be systemicaHy absorbed. For example, inhalers prescribed for asthmatics produce a fine mist that can penetrate into the bronchial tubes (see Antiasthmatic agents). 

Pharmaceutical powder aerosols have more stringent requirements placed upon the formulation regarding moisture, particle size, and the valve. For metered-dose inhalers, the dispensed product must be deflvered as a spray having a relatively small (3—6 -lm) particle size so that the particles can be deposited at the proper site in the respiratory system. On the other hand, topical powders must be formulated to minimize the number of particles in the 3—6-p.m range because of the adverse effects on the body if these materials are accidently inhaled. 

Mild exposure to HF via inhalation can irritate the nose, throat, and respiratory system. The onset of symptoms may be delayed for several hours. Severe exposure via inhalation can cause nose and throat bums, lung inflammation, and pulmonary edema, and can also result in other systemic effects including hypocalcemia (depletion of body calcium levels), which if not promptly treated can be fatal. Permissible air concentrations are (42) OSHA PEL, 3 ppm (2.0 mg/m ) as E OSHA STEL, 6 ppm (5.2 mg/m ) as E and ACGIH TLV, 3 ppm (2.6 mg/m ) as E. Ingestion can cause severe mouth, throat, and stomach bums, and maybe fatal. Hypocalcemia is possible even if exposure consists of small amounts or dilute solutions of HE. 

Oxygen inhalators are used as a first-aid measure for a long Hst of emergencies, including heart attacks and suffocation, and as a result are carried routinely by rescue squads. Oxygen—helium mixtures have proved beneficial in asthmatic attacks, because these permit more rapid flow of gas into congested areas of the respiratory system. 

Health and Safety Factors. Ttimesic acid is an irritant to the skin, eyes, and respiratory system (140). It is mildly toxic when iagested. The oral LD q ia tats has been reported as 8.4 g/kg (141). Ttimesic acid is flammable, and precautions similar to those noted for tetephthaUc acid and isophthahc acid as regards dust clouds and fire extinguishing agents should be followed. 

Inhalation of aerosols or heated vapors may result in irritation of the nose, throat, and upper respiratory system. Lower molecular weight and branched-chain amines are more volatile and can cause irritation if inhaled. Volatile amines are easily recognized by their unpleasant, fishy odor. 

Inhalation exposure to high concentrations of ethylene oxide has been reported to result in respiratory system irritation and edema (236). 

Hydrochloric acid Comhustion of coal or wastes containing chlorinated plastics Coal-fired boilers, incinerators Irritant to eyes and respiratory system... 

Much of the concern about particulate matter in the atmosphere arises because particles of certain size ranges can be inhaled and retained by the human respiratory system. There is also concern because particulate matter in the atmosphere absorbs and scatters incoming solar radiation. For a detailed discussion of the human respiratory system and the defenses it provides against exposure of the lungs to particulate matter, see Chapter 7. 

Because a filter sample includes particles both larger and smaller than those retained in the human respiratory system (see Chapter 7, Section III), other types of samplers are used which allow measurement of the size ranges of particles retained in the respiratory system. Some of these are called dichotomous samplers because they allow separate measurement of the respirable and nonrespirable fractions of the total. Size-selective samplers rely on impactors, miniature cyclones, and other means. The United States has selected the size fraction below an aerodynamic diameter of 10 /xm (PMiq) for compliance with the air quality standard for airborne particulate matter. 

B. Removal of Deposited Particles from the Respiratory System... 

The respiratory system has several mechanisms for removing deposited particles (8). The walls of the nasal and tracheobronchial regions are coated with a mucous fluid. Nose blowing, sneezing, coughing, and swallowing... 

Air pollution principally affects the respiratory, circulatory, and olfactory systems. The respiratory system is the principal route of entry for air pollutants, some of which may alter the function of the lungs. 

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