Chest
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The flow-resistive characteristics of a variety of commercially available expiratory positive-pressure valve systems used to provide continuous positive airway pressure (CPAP) and positive end-expiratory pressure were evaluated. One flow-resistor and seven threshold-resistor expiratory pressure valve systems were set at 5, 10, 15, 20, and 25 cm H2O of expiratory pressure, and sinusoidal exhaled flows peaking at 50,100, and 200 L/min were directed through each valve at each level of expiratory pressure. The Siemens flow-resistor valve demonstrated the greatest deviation in pressure above set CPAP levels at peak flow rates of 100 and 200 L/min, which suggests high resistance to exhaled flow. ⋯ The Emerson and IMV Bird threshold-resistor systems resisted flow less than the BEAR-2 and the Puritan-Bennett MA-2 and 7200 inflatable-balloon threshold-resistor-like valve systems. These data suggest that threshold resistors may be classified as low-resistance or high-resistance types. Using only low-resistance threshold resistors for CPAP may minimize the incidence of barotrauma and other deleterious effects related to airway pressure.
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The purpose of this study was to compare the efficacy of nasal oxygen delivery by an inspiratory demand valve, which delivers oxygen only during the inspiratory phase, to standard continuous flow oxygen. The inspiratory demand valve attaches to an oxygen source and delivers oxygen after the sensor detects negative pressure through a standard nasal cannula. Seventeen male patients with chronic hypoxemia secondary to COPD were studied under resting conditions. ⋯ The results indicate that oxygen saturation was not significantly different for either method of oxygen delivery at rest or during exercise. The time oxygen was delivered was significantly reduced during demand valve use, being 55 percent less at rest and 52 percent less during exercise when compared to continuous oxygen. Further study would be helpful to determine whether the device would reliably deliver oxygen during continuous use and whether it could be adapted to portable systems.
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Case Reports
Endocarditis of a tricuspid prosthesis causing valvular stenosis and shunting through a patent foramen ovale.
A young intravenous drug user presented with Staphylococcus aureus endocarditis involving the tricuspid valve, which was replaced with a Hancock bioprosthesis. She presented again with fever and dyspnea five months later and was found to be cyanotic. Recurrent endocarditis involving the prosthesis with right-to-left shunting through a patent foramen ovale was documented by echo and confirmed at autopsy.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intrathoracic intercostal nerve block with phenol in open chest surgery. A randomized study with statistical evaluation of respiratory parameters.
Seventy-three patients who underwent thoracic surgery were randomly selected for intraoperative intercostal nerve block using phenol (32 block and 41 control subjects). The patients were divided into three groups: pneumonectomies, lobectomies and explorative thoracotomies and evaluated by pain level, respiratory function parameters (VT, IRV, ERV, VC) and blood-gas analysis, both six and 24 hrs after surgery. The patients who had intraoperative nerve block using phenol enjoyed a more comfortable postoperative period. In particular, respiratory parameters were statistically better.
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Randomized Controlled Trial Comparative Study Clinical Trial
Esophageal gastric tube airway vs endotracheal tube in prehospital cardiopulmonary arrest.
We evaluated the efficacy of the esophageal airway (EA) by prospectively randomizing 175 prehospital cardiopulmonary arrest patients to receive either an esophageal gastric tube airway (EGTA) or an endotracheal tube (ET). If attempts with the initial airway failed, the alternate airway was attempted. The cost of training paramedics in EA use was considerably less than the ET ($80 vs $1,000). ⋯ The incidence of neurologic residual (ET 50 percent, EGTA 36.4 percent) and congestive heart failure (ET 40 percent, EGTA 45.5 percent) in surviving ET and EGTA patients did not differ (NS). An additional 125 consecutive patients with only the opportunity to receive an EA were also evaluated and did not differ in mortality, neurologic residual, or congestive heart failure from ET patients. We conclude that the EA is a satisfactory alternative to the ET for short-term prehospital use in cardiopulmonary arrest patients.