Respiratory care
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ARDS is an important cause of respiratory failure and continues to be associated with a high mortality rate. Numerous therapeutic interventions have been employed to improve patient outcomes, including inhaled epoprostenol. ⋯ Although the use of epoprostenol in ARDS remains a therapeutic challenge, we were able to identify predictors of mortality for this important cohort of patients. These predictor variables could be employed in the design of future trials of epoprostenol in ARDS.
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Comparative Study
Effect of the Anatomic Reservoir on Low-Flow Oxygen Delivery Via Nasal Cannula: Constant Flow Versus Pulse Flow With Portable Oxygen Concentrator.
The F(IO(2)) for a nasal cannula with constant flow (CF) depends on the anatomic reservoir (AR), which is affected by changes in frequency and end-expiratory flow. Conversely, pulse flow (PF) devices do not require the AR. The purpose of this study was to compare the F(IO(2)) delivered by a nasal cannula supplied by CF via oxygen tank with that delivered by PF delivered via portable oxygen concentrator. Hypotheses were (1) a lung model of COPD with non-zero end-expiratory flow decreases F(IO(2)) for CF more than for PF, and (2) CF and PF perform differently in terms of F(IO(2)) delivery, despite having equivalent settings. ⋯ CF oxygen delivery via a nasal cannula is significantly reduced by elimination of the AR in a model of COPD, yielding clinically important decreases in F(IO(2)). PF (delivered with a portable oxygen concentrator) is relatively unaffected. This study supports the recommendation that clinicians and caretakers should titrate the PF setting to each patient's unique oxygen requirements.
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The Acute Respiratory Distress Syndome (ARDS) Network low tidal volume (VT) trial paved the ground for mechanically ventilating ARDS patients with a VT of 6 mL/kg ideal body weight (IBW). Although there is no consensus that a low VT is advantageous in non-ARDS patients,it is accepted that high VT should be avoided. Because compliance rates with ventilator recommendations are 30%, there is a need for process improvement. We postulated that a computerized screen prompt that recommended VT based on height would improve compliance with low VT.During ventilator order entry, the computerized decision tool prompts the clinician and encourages ventilation of patients at 8 mL/kg IBW, and 6 mL/kg IBW for patients with ARDS. ⋯ A computerized clinical decision tool with the preferred initial VT settings based on the patients' sex and height is a safe and reliable way to increase low VT strategy compliance across multiple ICUs. Its limitations are similar to those shared by other computer-generated prompts.
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Ventilator management for children with hypoxemic respiratory failure may benefit from ventilator protocols, which rely on blood gases. Accurate noninvasive estimates for pH or P(aCO2) could allow frequent ventilator changes to optimize lung-protective ventilation strategies. If these models are highly accurate, they can facilitate the development of closed-loop ventilator systems. We sought to develop and test algorithms for estimating pH and P(aCO2) from measures of ventilator support, pulse oximetry, and end-tidal carbon dioxide pressure (P(ETCO2)). We also sought to determine whether surrogates for changes in dead space can improve prediction. ⋯ We have demonstrated a conceptual first step for predictive models that estimate pH and P(aCO2) to facilitate clinical decision making for children with lung injury. These models may have some applicability when incorporated in ventilator protocols to encourage practitioners to maintain permissive hypercapnia when using high ventilator support. Refinement with additional data may improve model accuracy.
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Positive airway pressure (PAP) in subjects with both obstructive sleep apnea and COPD reduces the risk of pulmonary hypertension, death, and hospitalizations from COPD exacerbations, but adherence to the intervention is low, similar to the experience with noninvasive ventilation in stable COPD. We sought to assess whether hyperinflation on chest radiographs contributes to low adherence to PAP therapy in the overlap syndrome. ⋯ Hyperinflation is associated with decreased adherence to PAP therapy in the overlap syndrome.