The control of ventilation

In metabolic acidotic disorders of acid-base physiology, it is the peripheral chemoreceptors which sense the pH of the extracellular fluid and cause the hyperventilatory compensatory response. 

---

The techniques for giving anaesthetic dmgs emd the control of ventilation and oxygenation are of great importance, but are outside the scope of this book. 

Explain the control of ventilation in a healthy person at sea level breathing air. 

The concentration of inorganic and organic chloramines in pool water is controlled by superchlorination or shock treatment. Because chloramines are decomposed by sunlight, their effects are more noticeable in indoor pools or spas. Nitrogen trichloride, the primary volatile chloramine, is a strong irritant similar to chlorine. Its effect is noticeable at >0.5 mg/m (>0.1 ppm) (73). The concentration of NCl depends on the extent of ventilation and typically varies from 0.2 to 0.5 mg /m (0.04 to 0.1 ppm) (74). 

Horizontal displacement ventilation (see Chapters 7 and 8) is a ventilation principle mainly applied to general ventilation of workrooms. In some instances, a local ventilation problem may be solved by building a separate enclosure or a room around the workstation and arranging for a general ventilation in that enclosure. An example where that principle has been utilized is the control of emissions of and worker exposure to styrene vapors during... 

Respiratory acidosis is characterized by a reduced arterial pH, a primary increase in the arterial PaC02 and, when present for sufficient time, a compensatory rise in the HCOf concentration. Because increased C02 is a potent respiratory stimulus, respiratory acidosis represents ventilatory failure or impaired central control of ventilation as opposed to an increase in C02 production. As such, most patients will have hypoxemia in addition to hypercapnia. The most common etiologies of respiratory acidosis are listed in Table 25-6. 

General dilution ventilation has the advantage of being relatively cheap to install and operate, but it is most effective only in the control of small quantities of mild to moderately toxic gases, mists, and fumes. It does not eliminate exposure, however, and it does not specifically control the exposure of the worker at the source. Furthermore, because of their relative density, it does not control heavy particulates or high density metal fumes, nor can it compensate for local changes in the generation of contaminants. 

Epidural/Intrathecal administration Limit epidural or intrathecal administration of preservative-free morphine and sufentanil to the lumbar area. Intrathecal use has been associated with a higher incidence of respiratory depression than epidural use. Asthma and other respiratory conditions The use of bisulfites is contraindicated in asthmatic patients. Bisulfites and morphine may potentiate each other, preventing use by causing severe adverse reactions. Use with extreme caution in patients having an acute asthmatic attack, bronchial asthma, chronic obstructive pulmonary disease or cor pulmonale, a substantially decreased respiratory reserve, and preexisting respiratory depression, hypoxia, or hypercapnia. Even usual therapeutic doses of narcotics may decrease respiratory drive while simultaneously increasing airway resistance to the point of apnea. Reserve use for those whose conditions require endotracheal intubation and respiratory support or control of ventilation. In these patients, consider alternative nonopioid analgesics, and employ only under careful medical supervision at the lowest effective dose. 

Some patients experience prolonged seizures, defined as a duration greater than 120 to 180 seconds. These patients require continued oxygenation, control of ventilation, and an i.v. bolus of the anesthetic agent (20 to 40 mg methohexital) or diazepam (2.5 to 5 mg) to abort the seizure. 

The plant areas are supplied with adequate ventilation sufficiently controlled for pressure, temperature, relative humidity, dust, and microorganisms and to sustain personnel comfort. The design of this system has filters, which aid in the control of microorganisms. 

O Shea TM, Kothadia JM, Klinepeter KL, Goldstein DJ, Jackson BG, Weaver RG III, Dillard RG. Randomized placebo-controlled trial of a 42-day tapering course of dexamethasone to reduce the duration of ventilator dependency in very low birth weight infants outcome of study participants at 1-year adjusted age. Pediatrics 1999 104(1 Part 1) 15—21. 

Ventilation is often adopted as a control measure to keep VOCs and C02 below specified threshold levels. The effect of operation of the ventilation system on spatial and temporal profiles is illustrated from two separate buildings. With adequate ventilation, the C02 levels are easily controlled within threshold levels. However, VOCs present a problem due to their build-up overnight between the time of ventilation shutdown after office hours and its reactivation in the morning just before occupancy. Purging the building as an effective means to reduce the exposure risks is discussed and illustrated. Some concluding remarks on other changes to indoor exposures are made at the end of the chapter. 

The control of intercurrent infectious diseases or parasites is facilitated if rodents are bred and maintained in conditions free from specific pathogenic organisms. Bedding used in long-term studies should be sterilized. Animals should be housed in quiet, well-ventilated rooms, with controlled lighting, temperature, and humidity. Experiments should not be initiated until animals have been allowed a period of acclimation to the environment. Neither conditions nor animals from outside sources should be placed in tests without an adequate period of quarantine. 

This book provides an advanced level of study of industrial hygiene engineering situations with emphasis on the control of exposure to occupational health hazards. Primary attention is given to industrial ventilation, noise and vibration control, heat stress, and industrial illumination. Other topics covered include industrial water quality, solid waste control, handling and storage of hazardous materials, personal protective equipment, and costs of industrial hygiene control. 

Warner JA, Frederick JM, Bryant TN, Welch C, Hunter C, Stephen FR, et al Mechanical ventilation and high-efficiency vacuum cleaning A combined strategy of mite and mite allergen reduction in the control of mite-sensitive asthma. J Allergy Clin Immunol 2000 105 75-82. (Ib)... 

Acidosis seen during cardiac arrest results from decreased blood flow and inadequate ventilation. Chest compressions generate approximately 20% to 30% of normal cardiac output, leading to inadequate organ perfusion, tissue hypoxia, and metabohc acidosis. In addition, the lack of ventilation causes retention of carbon dioxide, leading to respiratory acidosis. This combined acidosis produces not only reduced myocardial contractility and negative inotropic effect but also the appearance of arrhythmias because of a lower fibrillation threshold. In early cardiac arrest, adequate alveolar ventilation is the mainstay of control to limit the accumulation of carbon dioxide and control the acid-base imbalance. With arrests of long duration, buffer therapy often is necessary. 

---