Arch Surg Chicago
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A mixture of 80% helium and 20% oxygen has physical properties that increase airflow and decrease resistance in the airway when used as a portion of inspired gas. This study was designed to demonstrate and quantify the effects of a helium-oxygen mixture in a normal airway and when airway resistance is increased. Thirty healthy volunteers were studied breathing room air and the helium-oxygen mixture through a normal airway and an airway that included a resistor. ⋯ There was a statistically significant increase in 1-second forced expiratory volume using a helium-oxygen mixture in a normal airway. All pulmonary function test scores statistically improved when volunteers inspired helium and oxygen through the restricted airway, demonstrating that helium and oxygen can increase airflow in the presence of an increased airway resistance. This substantiates a role for helium and oxygen in treating conditions associated with decreased airway size and increased airway resistance.
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We studied the effects of laparoscopic cholecystectomy on respiratory and hemodynamic function in eight adult pigs. Minute ventilation was adjusted to normalize baseline arterial blood gases, then fixed throughout carbon dioxide insufflation. A metabolic measurement cart recorded total CO2 excretion, oxygen consumption, and minute ventilation. ⋯ We conclude that CO2 pneumoperitoneum resulted in significant transperitoneal CO2 absorption, with secondary hypercapnia and acidemia. The accumulation of CO2 was also associated with an increase in systemic and pulmonary arterial pressure. Heart rate increased to compensate for the decreased stroke volume to maintain cardiac output.
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The association of dilated peripheral arteries with aortic aneurysmal disease has previously been suspected, but is not well documented. To test this association, the diameters of the common femoral, popliteal, brachial, common carotid, internal carotid, and external carotid arteries were measured with a color-flow duplex scan in 30 control subjects and 36 patients with aortic aneurysm matched for age, sex, smoking habits, and hypertension. ⋯ Peripheral artery dilatation was identified at sites that are seldom, if ever, involved in atherosclerosis. These findings lend support to the view that there is a generalized dilating diathesis in aortic aneurysmal disease that may be unrelated to atherosclerosis.