Should tracheostomy be performed as early as 72 hours in patients requiring prolonged mechanical ventilation?

Advances in treating the critically ill have resulted in more patients requiring prolonged airway intubation and respiratory support. If intubation is projected to be longer than several weeks, tracheostomy is often recommended. Tracheostomy offers the potential benefits of improved patient comfort, the ability to communicate, opportunity for oral feeding, and easier, safer nursing care. In addition, less need for sedation and lower airway resistance (than through an endotracheal tube) may facilitate the weaning process and shorten intensive care unit and hospital stay. By preventing microaspiration of secretions, tracheostomy might reduce ventilator-associated pneumonia. There is controversy, however, over the optimal timing of the procedure. While there have been many randomized controlled trials on tracheostomy timing, most were insufficiently powered to detect important differences, and systematic reviews and meta-analyses are limited by the heterogeneity of the primary studies. Based on the available data, we think it is reasonable to perform early tracheostomy in all patients projected to require prolonged mechanical ventilation. Unfortunately, identifying those patients can be difficult, and for many patient populations we lack the necessary tools to predict prolonged ventilation. We propose an early-tracheostomy decision algorithm.

Two-dimensional phase unwrapping to help characterize an electromagnetic beam for quasi-optical mode converter design.

An improved two-dimensional phase unwrapping procedure is discussed that uses a weighted least-squares algorithm, a congruence operation, and a filter to unwrap the phase distribution of an electromagnetic beam. These improvements make possible several advances for mirror designs used in gyrotron quasi-optical mode converters. The improved phase unwrapping procedure is demonstrated by applying it to a measured beam and a simulated beam that are used to design mirrors. The unwrapping procedure produces a smooth unwrapped phase that does not change the characteristics of the beam. The smooth unwrapped phase distribution is also used to find an estimate for the wavenumber vector distribution that is needed to design the mirrors.

Lyme neuroborreliosis presenting as the syndrome of inappropriate antidiuretic hormone secretion.

We describe a case of a patient presenting with the syndrome of inappropriate hormone secretion (SIADH) caused by Lyme neuroborreliosis.