One of their most recent publications is Chapter 1 - Functional anatomy of the respiratory tract. Which was published in journal .

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J.F. Nunn's Articles: (20)

Chapter 1 - Functional anatomy of the respiratory tract

Publisher SummaryThis chapter explains the functional anatomy of the respiratory tract. The structural aspects of the function of the muscles of the mouth and pharynx are best considered in relation to a paramedian sagittal. The occlusion of the larynx is achieved in various stages ranging from whisper to speech with varying degrees of approximation of the vocal folds. The tighter occlusion can, however, be achieved for the purpose of making expulsive efforts. The trachea bifurcates asymmetrically, with the right bronchus being wider and making a smaller angle with the long axis of the trachea. It is, thus, more likely to receive foreign bodies. The main, lobar and segmental bronchi have firm cartilaginous support in their walls, U-shaped in the main bronchi but in the form of irregularly shaped and helical plates lower down. Where the cartilage is in the form of irregular plates, the bronchial muscle takes the form of helical bands that form a geodesic network. The bronchial epithelium is similar to that in the trachea, although the height of the cells gradually diminishes in the more peripheral passages until it becomes cuboidal in the bronchioles.

Chapter 3 - Resistance to gas flow and airway closure

Publisher SummaryThe excessive resistance to gas flow is the commonest and most important cause of ventilatory failure. The severe obstruction to breathing is life threatening and can arise anywhere from the smallest airways through the tracheobronchial tree, larynx, and pharynx to include external factors and any apparatus through which the patient can be breathing. The gas flows from a region of high pressure to one of lower pressure. The rate at which it does so is a function of the pressure difference and the resistance to gas flow. The precise relationship between pressure difference and flow rate depends on the nature of the flow that can be either laminar or turbulent or a mixture of the two. It is useful to consider laminar and turbulent flow as two separate entities but mixed patterns of flow usually occur in the respiratory tract. The viscosity is the only property of a gas that is relevant under the conditions of laminar flow.

Chapter 7 - Distribution of pulmonary ventilation and perfusion

Publisher SummaryThe distribution of the inspired gas can be considered in a number of contexts. Firstl, it can be considered purely as spatial distribution in relation to anatomical structures. Second, the distribution of inspired gas can be considered in terms of the rate at which different alveoli fill and empty. Finally, it can be considered in relation to the distribution of pulmonary blood flow, differentiating between the ventilation of unperfused alveoli at one extreme and the failure of ventilation of perfused alveoli at the other extreme. It frequently happens that these distinctions are not clearly made, and confusion can result from a failure to appreciate the precise meaning of the phrase distribution of inspired gas in a particular situation. The spatial distribution of inspired gas can be considered either in relation to the anatomy of the lungs or in terms of zones that relate to the anatomy of the trunk rather than the lungs themselves.

Chapter 13 - Respiratory aspects of sleep

Publisher SummaryThis chapter reviews the effects of sleep on respiration. The normal sleep in healthy subjects is accompanied by only minor changes in respiratory function. The muscles of respiration, including those concerned with the patency of the upper airway, continue their rhythmic discharge during normal sleep but there are special circumstances in which their function is deranged. The sleep is classified on the basis of the electroencephalogram (EEG) and electro-oculogram (EOG) into rapid eye movement (REM) and nonREM (stages1–4). Stage 1 is dozing from which arousal easily takes place. The EEG is low voltage and the frequency is mixed but predominantly fast. This progresses to stage 2 in which the background EEG is similar to stage 1 but with episodic sleep spindles and K complexes. The slow, large amplitude waves start to appear in stage 2 but become more dominant in stage 3 in which spindles are less conspicuous and K complexes become difficult to distinguish. In stage 4, which is often referred to as deep sleep, the EEG is mainly high voltage.

Chapter 14 - Respiratory aspects of high altitude

Publisher SummaryThis chapter discusses the respiratory effects of high altitude as it affects the aviator and the mountaineer. With increasing altitude, the barometric pressure falls but the fractional concentration of oxygen in the air and the saturated vapor pressure of water at body temperature remain constant. The influence of the saturated vapor pressure of water becomes relatively more important until, at an altitude of approximately 19,000 m or 63,000 feet, the barometric pressure equals the water vapor pressure, the body fluids boil, and the alveolar PO2 and PCO2 rapidly fall to zero. The acute effect of altitude on inspired PO2 can be simulated by the reduction of the oxygen concentration of gas inspired at the sea level. This provides the basis for much experimental work. Conversely, up to certain limits of altitude, it is possible to restore the inspired PO2 to the sea level value by increasing the oxygen concentration of the inspired gas.

Chapter 15 - Respiratory aspects of high pressure and diving

Publisher SummaryThis chapter reviews the salient features of those aspects of high pressure that concern the respiratory system together with an outline of the effects of inhalation of the various inspired gas mixtures that are used at high pressure. The man has sojourned temporarily in high pressure environments since the introduction of the diving bell. The environment of the diver is often, but not invariably, aqueous. The saturation divers spend most of their time in a gaseous environment in chambers that are held at a pressure close to that of the depth of water at which they work. The tunnel and caisson workers can also be at high pressure in a gaseous environment. The workers in both environments share the physiological problems associated with increased pressures and partial pressures of respired gases. However, those in an aqueous environment also have the additional effect of different gravitational forces applied to their trunks, which influence the mechanics of breathing and other systems of the body.

Chapter 20 - Ventilatory failure

Publisher SummaryThis chapter reviews most of the causes of failure of ventilation. The ventilatory failure is defined as a pathological reduction of the alveolar ventilation below the level required for the maintenance of normal arterial blood gas tensions. Mean of the normal arterial PCO2 is 5.1 kPa with 95% limits of ± 1.0 kPa. The normal arterial PO2 is more difficult to define as it decreases with age. Furthermore, the arterial PO2 is strongly influenced by the concentration of oxygen in the inspired gas and, therefore, cannot be interpreted unless the inspired oxygen concentration is known. The arterial PO2 is also strongly influenced by shunting and the adequacy of ventilation is, therefore, best defined by the arterial PCO2. A wide variety of drugs can cause central apnea or respiratory depression, and these include opiates, barbiturates, and all anesthetic agents. The reflex apnea can follow noxious stimuli but the Hering–Breuer inflation reflex is weak in man and lung inflation does not normally cause apnea.

Chapter 21 - Artificial ventilation

Publisher SummaryThe artificial ventilation is defined as the provision of the minute volume of respiration by external forces when there is impaired action of the patient's respiratory muscles. It is used in four main situations: (1) the resuscitation following acute apnea; (2) the anesthesia with paralysis; (3) the intensive care with failure of one or more vital functions; and (4) the prolonged treatment of chronic ventilatory failure. The extracorporeal gas exchange cannot really be considered as artificial ventilation. Much of the commonest application of artificial ventilation is during anesthesia with paralysis. It is normally applied to some 2–5% of the population of a developed country each year. Almost without exception, it is achieved by the application of intermittent positive pressure to the airway of the patient, either manually or by means of one of a large range of mechanical devices, which can be of a comparatively simple design. The artificial ventilation during intensive therapy is also undertaken almost exclusively by intermittent positive pressure ventilation.

Chapter 11 - Oxygen

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