The Journal of critical illness最新文献

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.

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. Regardless of the method you choose, begin weaning before the patient's lung function has returned to normal or baseline levels and end when the patient shows the minimum capacity necessary to sustain himself off the ventilator. 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.

Bronchoalveolar lavage (BAL) provides a means of recovering cells and biochemical substances directly from the alveoli in patients with numerous pulmonary diseases. It is also useful in diagnosing opportunistic infections in immunocompromised patients. Upper airway contamination of BAL specimens is the chief liability. In diffuse lung disease, the bronchoscope is usually positioned in the middle lobe; when focal lung disease is present, the bronchoscope is placed in the area of greatest roentgenographic involvement. Sterile saline is instilled and recovered for analysis. Most side effects are related to endoscopic technique, location and extent of lavaged lung area, and the volume and temperature of instilled fluid.

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. Before the bronchoscope is inserted, antisialagogues, anxiolytics, and topical anesthetics are administered along with supplemental oxygen. 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.

Aggressive treatment strategies that include early revascularization may significantly improve survival from acute MI complicated by cardiogenic shock. Symptoms of impending cardiogenic shock include tachycardia, cool extremities, pallor, cyanosis, and a normal or low blood pressure. When possible, the right and left sides of the heart are catheterized immediately. For patients who need to be transferred to a hospital with a catheterization laboratory, use temporary support measures--intubation, administration of positive inotropic agents, and placement of an intra-aortic balloon pump. Coronary angiography can reveal whether direct PTCA or bypass surgery is appropriate. Thrombolysis is limited to patients for whom transfer is delayed and those in whom cardiogenic shock is ruled out.

Potential indications for mechanical ventilation include hypoxemia unresponsive to oxygen administration, hypercapnia resulting in acidemia, and an unstable chest wall. For best results, carefully prepare the patient (both physically and emotionally) before instituting ventilation. Sedatives and local anesthesia can facilitate intubation; avoid paralytic agents unless you are experienced at intubation. The oral route is most commonly used. Once the patient circuit is attached to the endotracheal tube, reexamine the patient and double-check the inspiratory flow and I:E ratio; adjust the ventilator's settings as necessary. Monitor the patient frequently to ascertain the adequacy of alveolar ventilation and arterial oxygen.

Noninvasive monitoring techniques for assessing circulation during CPR include thoracic electrical bioimpedance and measurement of end-tidal carbon dioxide. Many dysrhythmias can be corrected with portable devices, such as automatic external defibrillation pacers, or with automatic implantable cardioverter-defibrillators or external transcutaneous cardiac pacers. Bradycardia is treated, however, only if it is accompanied by hemodynamically significant hypotension or ventricular ectopy. Adenosine may be preferable to verapamil for the management of paroxysmal supraventricular tachycardia. Three consecutive energy discharges are now recommended for the management of ventricular fibrillation.

Occlusive-cuff impedance plethysmography (IPG) is a rapid, reliable, and noninvasive method of diagnosing proximal deep venous thrombosis (DVT) in the lower extremities. The test is relatively easy to perform and carries an overall accuracy of greater than 90% when compared with venography. IPG is useful in detecting acute, symptomatic DVT and in determining the presence of recurrent DVT. In certain patients with nondiagnostic lung scans in whom pulmonary embolism is suspected, IPG may be helpful in determining appropriate therapy without use of pulmonary angiography.

Electrocardiography continues to be a cornerstone in the management of an array of cardiac and noncardiac disorders. However, the ease with which an electrocardiogram can be obtained, as well as its low cost, has led to widespread use--and possible overuse--of this technology. A joint committee of the American College of Cardiology and the American Heart Association recently published guidelines for appropriate use of electrocardiography in patients with known heart disease; in persons suspected of having, or who are at risk for, heart disease; and in persons with no apparent or suspected cardiac disease. These guidelines can help clinicians determine when, and for which patients in the intensive care unit, an electrocardiogram is warranted.