Respiratory Expiration

Forced vital capacity (FVC) quantifies the maximum air volume expired following a maximal inspiration and is one of the basic measures of analyzing flow changes such as reduced airway patency observed in asthma. To measure FVC, an individual inhales maximally and then exhales as rapidly and completely as possible. FVC primarily reflects the elastic properties of the respiratory tract. The gas volume forcibly expired within a given time interval, FEV (where t is typically one second, FEVj q)... 

Acute bronchospasm causes severe respiratory distress and wheezing from the forceful expiration of air and is considered a medical emergency, ft is characterized by severe respiratory distress, dyspnea, forceful expiration, and wheezing. The nurse must report these symptoms to the primary health care provider immediately. 

Sznadjer, J.I., Fraiman, A. and Hall, J.B. (1989). Increased hydrogen peroxide in the expired breath of patients with acute hypoxemic respiratory failure. Chest 96, 606-612. 

K8. Kietzmann, D., Kahl, R., Miiller, M., Burchardi, H., and Kettler, D., Hydrogens peroxide in expired breath condensate of patients with acute respiratory failure and with ARDS. Intensive Care Med. 19,78-81 (1993). 

Branching from the terminal bronchioles are the respiratory bronchioles. This is the first generation of airways to have alveoli in their walls. Finally, there are the alveolar ducts which are completely lined with alveolar sacs. This region, from the respiratory bronchioles through the alveoli, is referred to as the respiratory zone, which comprises most of the lungs and has a volume of about 3000 ml at the end of a normal expiration. 

Initial symptoms of COPD include chronic cough and sputum production patients may have these symptoms for several years before dyspnea develops. The physical examination is normal in most patients who present in the milder stages of COPD. When airflow limitation becomes severe, patients may have cyanosis of mucosal membranes, development of a barrel chest due to hyperinflation of the lungs, an increased resting respiratory rate, shallow breathing, pursing of the lips during expiration, and use of accessory respiratory muscles. 

Respiratory problems are diagnosed using a spirometer. The patient exhales as hard and as fast as possible into the device. The spirometer measures (1) the total volume exhaled, called the forced vital capacity (FVC), with units in liters (2) the forced expired volume measured at 1 second (FEV,), with units in liters per second (3) forced expiratory flow in the middle range of the vital capacity (FEV 25-75%), measured in liters per second and (4) the ratio of the observed FEVj to FVC X 100 (FEVj/FVC%). 

The absorption of inhaled -hexane has been investigated in six healthy male volunteers (Veulemans et al. 1982). Three different trials were performed on each volunteer 4-hour exposure at 102 ppm -hexane 4-hour exposure at 204 ppm, and exposure during exercise on a stationary bicycle ergometer at 102 ppm. Each trial was done at least two weeks apart. Lung clearance (from alveolar air to blood) and retention were calculated from -hexane concentrations in inhaled and expired air. After exposure, /7-hcxane in exhaled air was measured for up to 4 hours to determine respiratory elimination. Retention of -hexane (calculated from lung clearance and respiratory minute volume) was approximately 20-25%... 

Assume a respiratory rate of 12 min-1. From zero baseline, the curve initially rises slowly owing to the exhalation of dead space gas. Subsequently, it rises steeply during expiration to a normal value and reaches a near horizontal plateau after approximately 3 s. The value just prior to inspiration is the end-tidal C02 (Petco2). Inspiration causes a near vertical decline in the curve to baseline and lasts around 2 s. 

PAOP This must be lower than the PA diastolic pressure to ensure forward flow. It is drawn as an undulating waveform similar to the CVP trace. The normal value is 6-12 mmHg. The values vary with the respiratory cycle and are read at the end of expiration. In spontaneously ventilating patients, this will be the highest reading and in mechanically ventilated patients, it will be the lowest. The PAOP is found at an insertion length of around 45 cm. 

For regions in which the flow is not quasisteady, a transient-flow solution may be possible. For example, Lakin and Lakin and Fox developed a two-dimensional transient-flow solution for an idealized symmetric bifurcation during the period at the end of inspiration and before expiration. Their finding that vortidty decreases at the carina or bifurcation apex suggests that particle- and gas-deposition rates may be increased at these sites in the respiratory tract. It also suggests that reactive-gas deposition rates during normal oscUlatory breathing differ... 

The available data indicate that 2-hexanone is well absorbed after administration via the inhalation route. An analysis of the expired breath of humans who inhaled 2-hexanone at 10 or 50 ppm for 7.5 hours or 100 ppm for 4 hours indicated that 75%-92% of the inhaled 2-hexanone vapor was absorbed by the lungs and respiratory tract (DiVincenzo et al. 1978). 

In addition, oral administration of 1- C-2-hexanone to humans or rats results in the appearance of CO in the expired breath (DiVincenzo et al. 1977, 1978), indicating oxidation/cleavage of the alpha carbon. Administration of SKF525A (a mixed function oxidase inhibitor) to rats before oral administration of 2-hexanone resulted in a marked decrease in the excretion of respiratory CO for the first 4 hours after administration, followed by a marked increase at 4-8 and 12-24 hours. This suggests that this oxidative step is mediated by a microsomal mixed function oxidase system (DiVincenzo etal. 1977). 

Excess acid is partially managed by respiratory compensation, by which increased depth and speed of expiration (hyperventilation) ofC02 helps expel some of the acid, in addition to increased H excretion In the urine. 

The answer is C. Ingestion of an acid or excess production by the body, such as in diabetic ketoacidosis, may induce metabolic acidosis, a condition in which both pH and HCOj become depressed. In response to this condition, the carbonic acid-bicarbonate system is capable of disposing of the excess acid in the form of CO2. The equilibrium between bicarbonate and carbonic acid shifts toward formation of carbonic acid, which is converted to COj and HjO in the RBC catalyzed by carbonic anhydrase, an enzyme found mainly in the RBC. The excess CO2 is then expired by the lungs as a result of respiratory compensation for the acidosis (Figure 1-2). The main role of the kidneys in managing acidosis is through excretion of H" rather than CO2. 

Any volatile material, irrespective of its route of administration, has the potential for pulmonary excretion. Certainly, gases and other volatile substances that enter the body primarily through the respiratory tract can be expected to be excreted by this route. No specialized transport systems are involved in the loss of substances in expired air simple diffusion across cell membranes is predominant. The rate of loss of gases is not constant it depends on the rate of respiration and pulmonary blood flow. 

Desert rodents lead the most water-independent life of all vertebrates. Kangaroo rats can so reduce their evaporation that they are able to maintain water balance on only metabolic water. Other species survive on only meiabolic water plus free water in air-dry seeds. Respiratory water loss is reduced by cool nasal mucosal surfaces, which condense water from warm air coming from the lungs, before it can be expired. Skin impermeability involves a physical vapor barrier in the epidermis, pins unknown physiological factors. 

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