The Journal of critical illness
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Percutaneous tracheostomy is the procedure of choice for most patients who require prolonged use of an artificial airway; it can be performed rapidly at the bedside and is associated with fewer complications than is the standard procedure. The serial dilational technique involves the insertion of prelubricated dilators that gradually enlarge the diameter of a tract made by a guidewire and guiding catheter, facilitating placement of a standard double-cannula tracheostomy tube. The most dangerous complication, paratracheal insertion, occurs only rarely. The small skin incision and resulting tight fit of the tracheostomy tube in the stoma help prevent bleeding and infection.
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A variety of methods have been employed to help wean patients from prolonged ventilatory support. Although synchronized intermittent mandatory ventilation is probably the most widely used, it has not been shown to be clearly superior to T piece or pressure support weaning. ⋯ The patient's response to the change in the level of ventilatory support governs the rapidity of weaning. The rapid shallow breathing index can be useful in predicting weaning outcome, as is the patient's ability to tolerate a weaning trial.
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Fiberoptic bronchoscopy has a variety of applications in the intensive care unit. This procedure, which can be done at the patient's bedside, can be used to clear excess secretions; check the position of, or replace, an endotracheal tube; identify areas of active bleeding; diagnose opportunistic infections; and evaluate obstructive airway lesions. ⋯ In intubated, ventilated patients, a fiberoptic bronchoscope may be passed through a swivel adapter to prevent loss of the delivered oxygen and tidal volume. Cardiac arrhythmias and hypoxemia are among the most common complications.
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Inverse ratio ventilation (IRV) differs from other ventilatory techniques in that it employs a prolonged inspiratory time. In theory, pressure-control IRV allows you to maintain ventilation and oxygenation with lower peak airway and end-expiratory pressures; this may reduce the potential for lung damage secondary to shearing forces. ⋯ Currently, the chief limitation of this technique is that the patient cannot breathe spontaneously during its use. The best inspiratory to expiratory ratio is the shortest inspiratory time that improves oxygenation with minimal hemodynamic compromise; depression of cardiac output will negate any potential improvement in arterial oxygenation.
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Most modern ventilators have several key features in common: microprocessor control of operational and monitoring functions; electromechanical valves to control and adjust gas flow patterns; and extensive monitoring systems. In addition, these machines can provide a number of different modes of ventilation (including pressure support). Though not microprocessor-controlled, the Siemens Servo 900 series ventilators use feedback electronics to adjust inspiratory flow based on expiratory flow to meet preset volumes. In contrast, the Bennett 7200 units use microprocessor-regulated solenoid valves to deliver preset tidal volume. High-frequency ventilators deliver smaller tidal volumes at rates greater than 60 bpm.