![]() If this is not successful, then ventilation needs to be aided by mechanical means. The object of medical therapy is to decrease or reverse these acute respiratory loads thereby decreasing demand on fatiguing respiratory muscles. As examples, acute bronchospasm due to asthma or COPD places an increased resistive load on the respiratory system, acute pulmonary edema decreases lung compliance and thus places an increased elastance load on the system, and in COPD intrinsic PEEP increases the threshold load. This usually occurs when the respiratory loads are increased to the point where the respiratory muscles begin to fatigue and fail. More simply put, acute respiratory failure results when there is an imbalance between the respiratory muscle power available (supply) versus the muscle power needed (demand). Pmuscle is the pressure supplied by the Inspiratory respiratory muscles Papplied is the inspiratory pressure provided by mechanical means E is the elastance of the system R is the respiratory system resistance Threshold load is the amount of PEEPi or intrinsic PEEP the patient must overcome before inspiratory flow can begin Vt and V are the tidal volume and the flow rate respectively Inertia is a property of all mass and has minimal contributions and thus can be ignored clinically. Pmuscle + Papplied = E(Vt) + R(V) + threshold load + Inertia To that end, the "respiratory equation of motion" can provide a useful conceptual framework in determining why the patient is unable to sustain adequate minute ventilation. Since it is often necessary to initiate treatment before a clear diagnosis can be established, taking a pathophysiologic approach towards the patient can be useful. ![]() There are many possible etiologies for acute respiratory failure and the diagnosis is often unclear or uncertain during the critical first few minutes after ED presentation. The primary goals of this discussion will be to familiarize physicians with the many advantages of NIVS, to encourage its routine use, and to compare and contrast Continuous Positive Airway Pressure (CPAP) with Bi-level Positive Airway Pressure (BiPAP). Indeed, the use of NIVS in the Emergency Department is probably one of the most significant advances in the care of patients with acute respiratory failure in recent years. However, the increasing use of noninvasive ventilatory support (NIVS) has further decreased the need for endotracheal intubation in this patient population. In the past several years, more aggressive medical therapy with agents such as bronchodilators or nitrates (depending upon the underlying etiology), has resulted in less frequent need for intubation. If a patient progressed to the point were he was unable to sustain adequate oxygenation and ventilation on his own, then endotracheal intubation and positive pressure ventilation with a mechanical ventilator became necessary. Until recently, options for the treatment of severe acute respiratory failure were limited.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |