The jackknife technique in statistical analysis.

Communications to the Editor pulmonary toilet is often ineffective in clearing patients of these molasses-like secretions. Sputum retention should be considered in these presentations: COPD with frequent exacerbations requiring intermittent or chronic steroid therapy, slowly resolving pneumonia (particularly associated with debilitation), COPD or surgery, and intubated patients with thick secretions, disproportionate hypoxemia or those difficult to wean from the ventilator. The fiberoptic bronchoscope offers a low morbidity procedure to diagnose and remove these sputum plugs.