Chest
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Comparative Study
Conservation of oxygen supply using a reservoir nasal cannula in hypoxemic patients at rest and during exercise.
A reservoir nasal cannula which stores oxygen during exhalation and delivers it as a bolus during inhalation has been reported to conserve oxygen delivery in patients with chronic obstructive pulmonary disease (COPD) at rest. We compared the effects upon arterial oxygen saturation (SaO2) of the reservoir cannula and a standard nasal cannula in hypoxemic obstructed and restricted patients at rest and during exercise. The SaO2 was monitored by ear oximeter. ⋯ The SaO2 during exercise with the reservoir cannula was comparable to that with the standard cannula at approximately half of the oxygen flow rate. The ratio of the oxygen flow rate of the standard to the reservoir cannula to produce 90 percent saturation was estimated and found to be 2.5 +/- 0.8 (mean +/- SD) for patients at rest and 2.9 +/- 1.8 during exercise. We conclude that in hypoxemic patients at rest and during exercise, the reservoir cannula uses less than half the oxygen of a standard cannula to produce similar improvement in SaO2 and thus has advantages of a reduced cost of ambulatory therapy with low-flow oxygen and a longer time permitted away from a stationary source of oxygen.
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In unilateral parenchymal pulmonary disease, arterial oxygenation decreases when the patient is positioned such that the abnormal lung is dependent; however, few studies have evaluated the effect of the body position on oxygenation in patients with unilateral or asymmetric pleural effusions. To our knowledge, no previous study has evaluated the possible transient effects of changing position on the level of arterial oxygen saturation (SaO2) in such patients. Accordingly, we studied ten normoxic patients spontaneously breathing room air, who had asymmetric pleural effusions as documented by chest x-ray film and physical examination. ⋯ When the side with the pleural effusion was down, the mean SaO2 was significantly lower than in either the sitting position or with the side with the pleural effusion up. We could find no significant relationship between the size of the pleural effusion and the amount of arterial oxygen desaturation. We conclude that there is a decrease in SaO2 in normoxic patients when the side with the larger pleural effusion is dependent; however, this decreased SaO2 does not appear to be clinically significant in patients with normal SaO2.
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Two female patients with carcinoid heart disease, ages 56 and 32 years, underwent pulmonic valve resection surgery and tricuspid valve replacement with a porcine bioprosthesis. Preoperatively, both patients were in function class 4 with severe right-side congestive failure and signs of tricuspid regurgitation and pulmonic stenosis. Both underwent surgery for porcine tricuspid valve replacement (33 and 31 mm valves) and pulmonic valve resection. ⋯ Pre- and postoperative catheterization data documented hemodynamic improvements. One patient eventually died of hepatic failure due to metastatic disease. At autopsy, her bioprosthesis was free of carcinoid valvular changes.
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Comparative Study Clinical Trial
Pneumocystis carinii pneumonia in the patient with AIDS.
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Comparative Study
Etiology and prevention of topical cardiac hypothermia-induced phrenic nerve injury and left lower lobe atelectasis during cardiac surgery.
Left hemidiaphragm elevation is frequently noted following cardiac surgery employing topical hypothermia. We speculate that contact of the left phrenic nerve with ice causes nerve injury, resulting in left hemidiaphragm paresis or paralysis and left lower lobe atelectasis. Left diaphragm elevation was noted on postoperative chest x-ray examination of 36 of 60 (60 percent) consecutive patients in whom topical cooling of the heart with a cold slush solution was administered prior to use of a cardiac insulation pad (CIP, Shiley Laboratories, Irvine, California). ⋯ The use of topical cardiac hypothermia has been shown to protect the myocardium. Phrenic nerve injury secondary to the use of ice in this method has been documented. The use of a cold solution without ice chips or slush, or the insertion of a CIP prior to the use of topical cardiac hypothermia (when ice chips or slush are used) decreases the exposure of the phrenic nerve to cold injury and decreases the incidence of paresis of the left diaphragm and resultant atelectasis.