Respiratory mechanics

Cardiovascular and respiratory mechanisms in anaphylactic and anaphylactoid shock reactions. Klin... 

Bruner A.L. (1914). Jacobson s Organ and the respiratory mechanism of Amphibians. Morphol Jb 48, 157-165. 

Recently, Watanabe et observed dianges in respiratory mechanics... 

Earlier toxicity studies had suggested that the hazard from repeated ozone exposure might be reduced, inasmuch as animals became tolerant to the acute pulmonary edematogenic action of ozone. However, more recent studies, which demonstrated that tolerance to the ordinarily ozone-induced increase in susceptibility to infectious microorganisms or to the effects on respiratory mechanics does not develop, suggest that the tolerance phenomenon would have little protective value with respect to repeated exposure to ambient oxidant smog. 

All of the opioid analgesics can produce significant respiratory depression by inhibiting brainstem respiratory mechanisms. Alveolar Pco2 may increase, but the most reliable indicator of this depression is a depressed response to a carbon dioxide... 

Recent observations have shown a direct relation between the pH of the blood and the depth of hepatic coma (VI). They are interpreted as evidence that the intracellular ammonia is increased in alkalosis because it is un-ionized ammonia and not ammonium ion which readily diffuses into cells. This finding may be a result of the central action of ammonium on the respiratory mechanism (F7), rather than the primary cause of the coma. In this sense it would seriously enhance the coma and set up a cycle which would be lethal. However this may be, there is no mechanism presented for the actual toxic effect of ammonia per se, and the data, except for the internal inconsistencies noted in a previous part of this discussion, would be compatible with the ketoglutarate depletion hypothesis. 

N.R. Frank, et al., Effects of acute controlled exposure to SO2 on respiratory mechanics in healthy male adults. J. Appl. Physiol. 17 252-258, 1962. 

Frank, N.R., M.O.Amdur, and LL.Whittenberger. 1964. A comparison of the acute effects of S02 administered alone or in combination with NaCl particles in the respiratory mechanics of healthy adults. Int. J. Air Water Poll. 8 125-133. 

Tomasic M, Mann L S, Soma L R 1997 Effects of sedation, anesthesia and endotracheal intubation on respiratory mechanics in adult horses. American Journal of Veterinary Research 58 641-646 Trapani G, Altomare C, Liso G et al 2000 Propofol in anesthesia. Mechanism of action, structure-activity relationships, and drug delivery. Current Medicinal Chemistry 7 249-271... 

Respiratory Mechanism in the Regulation of Acid-Base Balance... 

In addition to supplying O2 to tissue cells for normal metabolism, the respiratory mechanism contributes to the maintenance of normal body pH through elimination... 

A number of lung diseases (e.g. chronic bronchitis and emphysema) are capable of producing shortness of breath that is often extremely distressing to the patient. Many of these conditions are irreversible, so it becomes necessary to target the symptom itself. The sensation of breathlessness is a complicated phenomenon that seems to depend upon central processing through respiratory and non-respiratory mechanisms (Guz 1996). Ideally, a treatment would relieve the unpleasant sensa-... 

The major source of acid is CO2, which reacts with water to produce carbonic acid. To maintain the pH of body fluids in a range compatible with life, the body has buffers such as bicarbonate, phosphate, and hemoglobin (see Fig 4.1). Ultimately, respiratory mechanisms remove carbonic acid through the expiration of CO2, and the kidneys excrete acid as ammonium ion (NHfi) and other ions. 

The effects of a drug upon circulation and respiration are of prime importance in determining their safety in clinical use. If one follows published opinion one must come to the conclusion that morphine depresses the respiratory center. If one analyzes the published data, it is difficult to substantiate such a decision. Extensive data on the respiratory effects of morphine in the rabbit, dog, and cat are available and have been discussed in detail elsewhere (1). The concept of a depression of the respiratory center by morphine was initiated by the ex cathedra statement of van Bezold (22). Fluorens paper (23) on the location of the vital node or the first motor point of the respiratory mechanism had been published a few years earlier, and this probably served to focus attention on the respiratory center and led to the very logical explanation of decreased respiratory movements on the basis that morphine depressed the respiratory center. 

It is known that respiratory stimuli elicit neural activity in suprapontine areas (O Donnell et al. 2007). hi human studies (Fig. 1) respiratory-related evoked potentials (RREP), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI) have been used to study human brain activity induced by respiratory mechanical loads, reducing tidal volume, hypercapnia, and hypoxia (O Donnell et al. 2007). Neural activation has been reported in the primary sensory cortex, thalamus, hypothalamus, anterior cingulate, amygdala, anterior insular... 

Carbon dioxide is produced as a byproduct of exercise metabolism, and breathing is stimulated during exercise to remove this CO2 excess. In this case, however, all the metabolically produced CO2 is removed and there is no measurable increase of CO2 dissolved in the blood. Furthermore, inhaled CO2 during exercise results in an increase of dissolved CO2 just as it did at rest. This difference between responses to inhaled CO2 and metabolically produced CO2 has baffled scientists and engineers for many years. Exercise apparently recruits different respiratory mechanisms to compensate for CO2 produced internally. Some (Whipp, 1981) have... 

Two important parameters of respiratory mechanics are resistances and compliances (compliance is the name given to capacity in fluid flow systems—see Sections 2.1 and 2.9). Resistances to air flow are distributed throughout the respiratory airways, lung tissue, and chest wall. The upper (larger) airways are usually considered separately from the lower airways because they have different mechanical properties and higher flow rates. The relationship between pulmonary resistance (excluding upper airway resistance) and body mass is seen in Figure 7.4.15, and equations are (Johnson, 2007)... 

Lanteri CJ, Sly PD. Changes in respiratory mechanics with age. J Appl Physiol 1993 74 369-378. 

American Thoracic Society/European Respiratory Society. Respiratory mechanics in infants physiologic evaluation in health and disease. Am Rev Respir Dis 1993 147 474 96. 

Hantos, Z., Daroczy, B., Suki, B., and Nagy, S. 1990. Low-frequency respiratory mechanical impedance in rats. /. Appl. Physiol. 63 36--43. 

Chapter 11 presents models used to study the continual interaction of the respiratory mechanical system and pulmonary gas exchange. Traditionally, the respiratory system is described as a chemo-stat — ventilation increases with increased chemical stimulation. Alternatively, the author proposes that quantitative description of the respiratory central pattern generator, a network of neuronal clusters in the brain, is a much more sophisticated and realistic approach. Study of this dynamic, optimized controller of a nonlinear plant is interesting from both physiological and engineering perspectives, the latter due to applications of these techniques for new, intelligent control system design. 

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