Respiratory care
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Randomized Controlled Trial
Home unattended portable monitoring and automatic CPAP titration in patients with high risk for moderate to severe obstructive sleep apnea.
Obstructive sleep apnea is a disorder characterized by recurrent obstruction of the upper airways during sleep. The high prevalence of this disease led to proposed new strategies based on the home evaluation and management of patients. ⋯ A home diagnosis and titration approach should be considered in a subset of patients with obstructive sleep apnea. A single unattended titration night is sufficient to determine the therapeutic pressure.
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The resistance of the endotracheal tube (ETT), the heat and moisture exchanger (HME), and the ventilator may affect the patient's respiratory status. Although previous studies examined the inspiratory work of breathing (WOB), investigation of WOB in the expiratory phase is rare. We estimated tracheal pressure at the tip of the ETT (Ptrach) and calculated expiratory WOB imposed by the ETT, the HME, and the expiratory valve. We examined imposed expiratory WOB in patients under a continuous mandatory ventilation (CMV) mode and during spontaneous breathing trials (SBTs). We hypothesized that imposed expiratory WOB would increase with heightened ventilatory demand. ⋯ Under mechanical ventilation, imposed expiratory WOB should be considered in patients with higher minute ventilation.
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In patients with COPD, chronic anemia is known as an unfavorable prognostic factor. Whether the association between hemoglobin (Hb) levels and long-term survival is restricted to anemia or extends to higher Hb levels has not yet been systematically assessed. ⋯ In subjects with COPD and chronic respiratory failure undergoing treatment with noninvasive ventilation and LTOT, high Hb levels are associated with better long-term survival. The optimal cutoff level for prediction was above the established threshold defining anemia. Thus, predicting survival only on the basis of anemia does not fully utilize the prognostic potential of Hb values in COPD.
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Comparative Study
Albuterol delivery by 4 different nebulizers placed in 4 different positions in a pediatric ventilator in vitro model.
The type of aerosol generator and the position in the ventilator circuit are crucial to determine aerosol delivery during mechanical ventilation. We compared lung deposition of albuterol aerosols generated by 4 different nebulizers placed in-line in 4 different positions in a pediatric ventilator model. ⋯ The vibrating mesh nebulizer was the most efficient device. The nebulizers were more efficient when placed at either the ventilator or the humidifier, and less efficient when placed at either the Y-piece or 30 cm from the Y-piece. These conclusions are valid for the tested conditions. Data regarding optimization of operating conditions should not be extrapolated among nebulizers of different operating principles.
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Comparative Study
Calculation of physiologic dead space: comparison of ventilator volumetric capnography to measurements by metabolic analyzer and volumetric CO2 monitor.
Calculation of physiologic dead space (dead space divided by tidal volume [VD/VT]) using the Enghoff modification of the Bohr equation requires measurement of the partial pressure of mean expired CO2 (PĒCO2) by exhaled gas collection and analysis, use of a metabolic analyzer, or use of a volumetric CO2 monitor. The Dräger XL ventilator is equipped with integrated volumetric CO2 monitoring and calculates minute CO2 production (VCO2). We calculated PĒCO2 and VD/VT from ventilator derived volumetric CO2 measurements of VCO2 and compared them to metabolic analyzer and volumetric CO2 monitor measurements. ⋯ PĒCO2, and therefore VD/VT, can be accurately calculated directly from the Dräger XL ventilator volumetric capnography measurements without use of a metabolic analyzer or volumetric CO2 monitor.