Critical care clinics
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As mechanical ventilators become increasingly sophisticated, clinicians are faced with a variety of ventilatory modes that use volume, pressure, and time in combination to achieve the overall goal of assisted ventilation. Although much has been written about the advantages and disadvantages of these increasingly complex modalities, currently there is no convincing evidence of the superiority of one mode of ventilation over another. Pressure control ventilation may offer particular advantages in certain circumstances in which variable flow rates are preferred or when pressure and volume limitation is required. The goal of this article is to provide clinicians with a fundamental understanding of the dependent and independent variables active in pressure control ventilation and describe features of the mode that may contribute to improved gas exchange and patient-ventilator synchronization.
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Patients in extremis because of trauma-related massive chest injury require expedient evaluation and prompt intervention. The initial pathophysiology relates to the significant intrapulmonary shunting caused by disruption of pulmonary capillaries and extravasation into the alveolar spaces. ⋯ Independent lung ventilation (mostly with unilateral lung involvement) and other strategies like inhaled nitric oxide, prone positioning, partial liquid ventilation, and extracorporeal membrane oxygenation (ECMO) have had good results. Intensivists confronted with this clinical subset may consider using these strategies as alternative/adjunctive options for optimizing respiratory and hemodynamic status in the supportive management of trauma-related acute lung injury (ALI) and adult respiratory distress syndrome (ARDS).
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Noninvasive positive-pressure ventilation (NPPV) is the delivery of mechanical-assisted breathing without placement of an artificial airway such as an endotracheal tube or tracheostomy. During the first half of 20th century, negative-pressure ventilation (iron lung) provided mechanical ventilatory assistance. By the 1960s, however, invasive (ie, by means of an endotracheal tube) positive-pressure ventilation superseded negative-pressure ventilation as the primarily mode of support for ICU patients because of its superior delivery of support and better airway protection. ⋯ This article explores the trends regarding the use of noninvasive ventilation. It also provides a current perspective on applications in patients with acute and chronic respiratory failure, neuromuscular disease, congestive heart failure, and sleep apnea. Additionally, it discusses the general guidelines for application, monitoring, and avoidance of complications for NPPV.
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Critical care clinics · Apr 2007
ReviewVentilatory management in patients with chronic airflow obstruction.
Mechanical ventilatory support allows patients who have CAO to gain time for pharmacologic treatment to work and to avoid and/or recover from respiratory muscle fatigue. The cornerstone to avoiding associated morbidity with mechanical ventilation in these patients is to prevent dynamic hyperinflation of the lung by limiting minute ventilation and maximizing time for expiration and by inducing synchronization between the patient and mechanical ventilator. ⋯ Patients who have CAO requiring mechanical ventilatory support have an increased risk of death following such an event. Therefore, careful followup is needed after hospital discharge.
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The rational for using closed loop ventilation is becoming strong and stronger. Studies are now available supporting the hypothesis that patient outcome is improved by using closed loop ventilation. ⋯ Introducing novel graphical user interfaces and providing data displays that are pertinent, integrative and dynamic will reduce cognitive resources of the clinician and have the potential to make ventilation safer. They may be the key to adopt closed loop ventilation in everyday practice.