The Journal of critical illness最新文献

The initial work-up of a critically ill patient with fever begins with a hunt for an infectious cause. A positive urine culture, or the presence of dysuria or suprapubic tenderness, suggests urinary tract infection. Diagnosing pneumonia in ventilated patients is particularly difficult; CT may be helpful when chest films are hard to interpret. Blood cultures can rule out septicemia. Other common causes of fever in the ICU include abdominal abscesses and catheter-related infections; atelectasis has not been shown to cause fever. If the initial work-up fails to establish a cause of postoperative fever, and the fever resolves within 4 days, no further work-up is required.

Fever is common in the ICU because of patients' underlying chronic and critical illnesses, their tendency to receive multiple medications, and their frequent need for invasive procedures. Precise data on the etiology of fever in the ICU are lacking. However, common noninfectious causes include postoperative fever, drug fever, intramuscular injections, hemorrhage, and pulmonary atelectasis. Urinary tract infection appears to be the most common infectious cause, followed by pneumonia and sepsis. Many noninfectious conditions are potentially life-threatening; nevertheless, it is crucial to first exclude an infectious cause, since an untreated infection may cause rapid deterioration.

Most cases of antibiotic-associated diarrhea are due to Clostridium difficile or are of enigmatic etiology. The antibiotics most often implicated are clindamycin, ampicillin or amoxicillin, and the cephalosporins. Clinical signs of antibiotic-associated diarrhea may be limited to watery stools; however, evidence of colitis (fever, cramps, leukocytosis, fecal leukocytes) suggests C. difficile infection. The tissue culture assay for C. difficile toxin remains the gold standard for diagnosis, but the enzyme immunoassay is a practical and reasonably accurate alternative. Anatomic changes, such as pseudomembranes, can be confirmed with endoscopy, but such evaluation is not required for diagnosis of C. difficile-associated pseudomembranous colitis.

Pleurodesis may be indicated for pleural effusions (with careful patient evaluation) or recurrent pneumothoraces. It is contraindicated if tube thoracostomy fails to reexpand the lung and, possibly, if patients are candidates for lung transplantation or have congestive heart failure. We perform pleurodesis through an indwelling chest tube (alternative methods are thoracoscopy and thoracotomy). Common sclerosants include talc, doxycycline, minocycline, and bleomycin. Intrapleural administration of lidocaine may control pain, but injections of morphine or meperidine almost always are needed.

In patients with obstructive lung disease, a strategy of mechanical ventilation that prolongs expiratory time and limits lung hyperinflation can decrease barotrauma. To prolong expiratory time, decrease minute ventilation and inspiratory time. Side effects of this strategy--high peak pressures and hypercapnia--are generally well tolerated. Additional goals for COPD patients include resting and strengthening respiratory muscles and decreasing load on the respiratory system. Short-acting benzodiazepines and morphine are effective for sedation and analgesia. Paralytic agents should be considered only if adequate control of the patient's cardiopulmonary status cannot be achieved by sedation alone.

Most ICU patients are at high risk for developing deep venous thrombosis; thus, they should be considered candidates for prophylaxis against pulmonary emboli (PE). If early ambulation is not an option, give low-dose heparin or apply lower extremity pneumatic compression. When PE cannot be prevented, rapid treatment is mandatory. Inotropic agents can be used to improve right ventricular contractility; however, the role of volume loading for augmenting preload is controversial. Heparin is the first-line therapy for halting ongoing thrombosis; administer a 5,000- to 10,000-U bolus, followed by a continuous infusion of about 35,000 U/d. Thrombolysis, embolectomy, and occlusive devices are other therapeutic options.

The kidneys are the primary site of aminoglycoside clearance; any factor that permits renal parenchymal accumulation increases the risk of aminoglycoside nephrotoxicity. The most common underlying cause is excessive aminoglycoside administration (especially in women or elderly patients). To minimize the risk of nephrotoxicity, select loading and maintenance aminoglycoside dosages based on estimated creatinine clearance. Also, monitor peak and trough serum aminoglycoside levels, replenish volume, and correct potassium and magnesium abnormalities. If possible, avoid giving aminoglycosides to patients with hepatic dysfunction or to those receiving other nephrotoxic drugs or radiocontrast agents.

Consider percutaneous transthoracic needle aspiration biopsy when specimens of pulmonary malignancies or infections are needed and bronchoscopy is contraindicated or the lesion is in a peripheral location. Percutaneous needle aspiration biopsy can be performed rapidly, and its diagnostic yield is good to excellent. The chief limitation of this procedure is the high incidence of pneumothorax, which makes the technique unsuitable for ventilated patients. A needle is inserted through the chest wall under fluoroscopic or CT guidance; a small sample is then aspirated through the needle. Operator skill and the use of thin needles help reduce the incidence of complications.

The current health care reform movement offers unique opportunities to address the issue of futile care. Possible solutions include the widespread use of advance directives, particularly durable power of attorney and cardiopulmonary resuscitation directives; the establishment of regional consortia for developing guidelines for the reasonable termination of care; and the use of patient registries and structured outcome studies to identify patients for whom treatment is likely to be futile. In addition to developing guidelines, regional consortia can serve as monitors for insurers or managed care plans that may attempt to limit care inappropriately.

Early, repeated defibrillation is the key to managing ventricular fibrillation (VF). To maximize the likelihood of success, use this five-phase approach, modified from the advanced cardiac life support protocols. Phase I: When a patient is found in VF and with no pulse or signs of life, attempt electrical reversion with a 200-wsec shock, followed if necessary by a 300-wsec and a 360-wsec shock. Phase II: Manage reversible causes of VF with orotracheal intubation, hyperventilation, and epinephrine. Phase III: Use intravenous lidocaine aggressively, followed by a 360-wsec shock. Phase IV: Give bretylium and magnesium sulfate by intravenous push, again followed by a 360-wsec shock. Phase V: Treat refractory VF with repeated 360-wsec shocks, and give further doses of the anti-arrhythmic agents.