Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Q: Abstract: The influence of some extreme body postures on vital capacity (VC) was examined in young adult humans. Two postures required full support of body weight by the arms: arms up, hanging from a bar, and arms down with hands gripping parallel bars. Three involved muscles that flex and extend the trunk: a partial sit-up position while supine and nearly maximal spinal extension and flexion while standing. Changes at the inspiratory and expiratory volume extremes were recognized by having the subjects do two VC efforts: the first standing and the second in the posture in question while continuing to breathe on the spirometer. Control observations in which the second of a VC pair was performed in an unstressed posture allowed correction for the influence of rebreathing. The changes in corrected VC were small, the greatest being an average reduction of approximately 8% in the partial sit-up position. During full support of body weight by the arms, the VC was slightly increased due to a significant increase in the inspiratory extreme and no change in the expiratory extreme. Spinal extension produced small increases in lung volume at both extremes with no significant change in VC, whereas spinal flexion did not influence the upper extreme but did increase lung volume at the lower extreme. The changes are discussed in terms of trunk muscle action.

A: Effect of posture on vital capacity.
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Q: Abstract: Pulmonary edema due to upper airway obstruction can be observed in a variety of clinical situations. The predominant mechanism is increased negative intrathoracic pressure, although hypoxia and cardiac and neurologic factors may contribute. Laryngospasm associated with intubation and general anesthesia is a common cause of pulmonary edema in children. However, only seven cases of pulmonary edema presumably due to laryngospasm have been reported in adolescents and adults. Five of the seven had other risk factors for upper airway obstruction, and in four, the diagnosis of "laryngospasm" could be explained by other factors. Patients with underlying risk factors for upper airway obstruction, such as a forme fruste of sleep apnea or nasopharyngeal abnormalities, appear to be at increased risk for the development of pulmonary edema in the setting of intubation and anesthesia. This form of pulmonary edema usually resolves rapidly without the need for aggressive therapy or invasive monitoring.

A: Post-extubation pulmonary edema following anesthesia induced by upper airway obstruction. Are certain patients at increased risk?
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Q: Abstract: By use of an improved density measuring system, we found that the gravimetric density of arterial blood of dogs fluctuates at the same frequency as the spontaneous or mechanical ventilation. Similar density fluctuations were observed in the blood leaving isolated, perfused lobes of dogs that were ventilated cyclicly. Employing an analysis that balanced the erythrocyte and plasma flows through distensible capillaries containing blood with a tube hematocrit lower than the hematocrit in large blood vessels, we derived a relationship to estimate from the density fluctuation the change in pulmonary capillary blood volume (Vc). For mechanical ventilation, the maximum change in density over one ventilation cycle increased from 0.084 +/- 0.01 to 0.47 +/- 0.05 (SE) g/l as the frequency decreased from 29 to 6 cycles/min. These density changes were estimated to be the result of an 1-16% change in Vc. A larger tidal volume for the mechanical ventilation led to a larger density fluctuation. The maximum density change of spontaneous respiration of 6 cycles/min was one-sixth of the mechanical case, indicating a much smaller change in Vc during spontaneous respiration. When the airway flow resistance was increased for spontaneous respiration, larger density fluctuations were observed.

A:
Ventilatory changes of pulmonary capillary blood volume assessed by arterial density.
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