P.T. asks, "What is the purpose of downsizing?"
Answer: The purpose of downsizing is to allow the patient to do more breathing around the tube, rather than through the tube. When the initial problem that initiated placement of the trach is resolved, downsizing may begin. For example, when the tube was placed because of prolonged mechanical ventilation, downsizing can begin as soon as the patient has been weaned from the ventilator.
Downsizing should begin with cuff deflation, which allows admixture of room air, lowering overall FiO2. So downsizing should not begin until the patient is hemodynamically stable and can tolerate cuff deflation.
When the patient is able to tolerate cuff deflation, the tube can be changed to one with a smaller outer diameter. Capping can begin at that time (and never with a standard cuffed tube).
The end result of downsizing is usually with the overall goal of decannulation; however, the tube may need to be downsized in order to allow enough air around the tube to reach the vocal cords for phonation. See the Downsizing Algorithm in Chapter 11 for a step-wise procedure on downsizing.
Sunday, May 30, 2010
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.
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.
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