Resp Care
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The history of oxygen from discovery to clinical application for patients with chronic lung disease represents a long and storied journey. Within a relatively short period, early investigators not only discovered oxygen but also recognized its importance to life and its role in respiration. The application of oxygen to chronic lung disease, however, took several centuries. ⋯ It took brazen clinicians, however, to pursue oxygen as a therapeutic resource for patients with chronic lung disease because of the concern in the 20th century of the risks of oxygen toxicity. Application of ambulatory oxygen devices allowed landmark investigations of the long-term effects of continuous oxygen that established its safety and efficacy. Although now well established for hypoxic patients, many questions remain regarding the benefits of oxygen for varying severity and types of chronic lung disease.
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The physiologic changes that occur in ventilation during sleep contribute to nocturnal oxygen desaturation in those with lung disease. Nocturnal supplemental oxygen is often used as therapy, although convincing data exist only for those who are hypoxemic both during sleep and wake. ⋯ Because of its prevalence, obstructive sleep apnea may commonly overlap with lung disease in many patients and have important consequences. Patients with overlap syndromes may be good candidates for noninvasive ventilation during sleep.
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The beneficial effects of ambulatory home oxygen have been demonstrated since the 1950s, when Cotes and Gibson gave oxygen to ambulatory COPD patients from small portable high pressures cylinders in the United Kingdom. Over the ensuing 7 decades, oxygen has been prescribed to millions of COPD patients in the home setting. Additionally, it is common clinical practice to prescribe supplemental oxygen when chronic hypoxemic respiratory failure not due to COPD (eg, interstitial lung disease, pulmonary hypertension, kyphoscoliosis, and cystic fibrosis) is present or in patients with hypoxemia at hospital discharge following flares of their underlying chronic respiratory disorder, without any substantial evidence. ⋯ Research conducted in the 1970s and 1980s still provides the basis for clinical decision making and insurance coverage policies regarding long-term oxygen administration. Remarkably, little current research is being conducted to extend our knowledge regarding the indications, mechanisms, and benefits of long-term oxygen therapy. This review will focus on our current knowledge of the end points for supplemental oxygen at home, such as mortality, effects on functional performance, sensation of dyspnea, cognitive function, and quality of life, and highlight areas where future research is needed.
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The nasal cannula has been a commonly used patient interface to provide supplemental oxygen since its introduction in the 1940s. Traditionally, it has been categorized as a low-flow device and capable of delivering a 0.4 F(IO(2)) with flows up to 6 L/min to adults with normal minute ventilation. However, there is considerable performance variability among patients and design, which results in an exponential decline in delivered F(IO(2)) as breathing frequencies increase. ⋯ HFNC therapy has also been considered valuable in perinatal care in treating the respiratory distress syndrome or supporting patients after extubation similar to nasal CPAP. At present, research-based evidence for the role of HFNC for its perinatal applications remains unclear. This review will identify proposed mechanisms for therapeutic effectiveness, current delivery equipment, guidelines for rational patient application, and direction for further research.
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The management of patients with traumatic brain injury has evolved in the last several years, due to the introduction of new, invasive monitoring devices. The ability to monitor parameters other than measurements related to pressures has generated substantial interest. Brain tissue oxygenation monitoring has been consistently shown to provide prognostic information, as indicated by poor prognosis associated with low brain tissue oxygen values. ⋯ Retrospective studies suggest benefit, while prospective studies have shown a higher intensity of therapeutic interventions with no outcome differences. Data from high quality randomized trials are necessary to determine if brain-oxygenation-guided therapy is beneficial. An oxygen challenge (transient increase in F(IO(2)) to 0.6 up to 1.0) to assess the responsiveness of the monitoring and ascertain the presence of technical malfunction is an accepted practice.