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Thursday, May 6, 2010

Water or Saline?

A respiratory therapy student asks, "What am I supposed to use to inflate the cuff of a Bivona TTS trach? I've heard they should be inflated with water, but I've also heard saline. Which is it...and why?"

Answer: The Bivona TTS and the Arcadia CTS tubes are both made of silicone with high-pressure, low-volume cuffs. These cuffs are in contrast to the majority of tracheostomy tubes out there (most are low-pressure, high-volume). When inflated, they create pressures greater than 120 cm H2O, even when only slightly inflated. So direct measurement of cuff pressure is not useful. When extended cuff inflation is desired (as for intermittent mechanical ventilation), they should be inflated with sterile water (not saline), using minimal leak technique. Saline has been shown to degrade the cuff over time. Sterile water is preferable for cuff inflation because air can diffuse through the cuff over time and manifest as cuff deflation.

Historically, the first cuffs to appear on tracheostomy tubes were also high-pressure, low volume. These cuffs created significant tracheal damage, and intermittent cuff deflation was recommended to relieve pressure against the trachea. Over the years, low-pressure, high-volume cuffs were developed that helped to minimize tracheal damage due to cuff inflation.

The primary benefit of these high-pressure cuffs is their deflation characteristics. When deflated, the cuff lies snugly against the shaft of the tube, lessening resistance to airflow passing around the tube. These tubes are ideal for a patient who requires intermittent cuff inflation, but they are the only cuffed tubes that can be safely capped when deflated.

1 comment:

  1. Still, even with using sterile water in the cuff, it will still apply pressure to the tracheal tissue, is that not correct? How can you determine how much pressure is being exerted on the tissue? I realize that saying it is not an exact science is a major understatement, but still..