The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

A Comparison of Once a Day SBT Without Daily Weaning Parameters VS. BID SBT's and Daily Weaning Parameters in a Burn/Trauma ICU

David Grooms BS, RRT, Steve Sibole BA, RRT, Jay Collins MD, Leonard Weireter MD, Frederick Cole MD.  Sentara Norfolk General Hospital, Norfolk, VA.

Background: Liberating from mechanical ventilation is a scientific process that has long been studied and evaluated, and to this day still is a subject of debate in our ICU's. Evidence Based Medicine (EBM) guidelines for discontinuing mechanical ventilation recommend daily evaluations of ventilator discontinuance by a formal patient assessment and once a day spontaneous breathing trial (SBT).  On September 1, 2005 we implemented a once daily SBT protocol that did not involve routinely obtaining weaning parameters (WP) and compared the outcomes to our historical control group that received daily WP and BID SBT's. We hypothesized that there would be no significant difference in Median VLOS or Re-intubation rates between groups.

 Historical Control Group (Group A, N=184) consisted of all patients in our Burn/Trauma unit placed on mechanical ventilation from January 1, 2005 to August 31, 2005.  Study group (Group B, N=149) consisted of all patients placed on mechanical ventilation from September 1, 2005 to March 31, 2005. The historical control group used a standard weaning protocol that involved formal daily wean assessments, daily weaning parameters, and BID SBTs. WP were obtained on Spont. mode, PS 0, & PEEP 0 for 3-5 minutes.  BID SBT's consisted of a variety of PEEP levels based on patient status, and PS titrations were made to maintain F/Vt 80-105. A minimum four hour rest period was provided after the first SBT. After the second SBT, the patient was returned back to previous rest settings for the remainder of the evening, and the process was repeated the following day.  The patient was extubated when they successfully completed a 2 hour PSminimum (PSmin) trial with F/Vt <105 and subjective assessment indicating little to no Work of Breathing (WOB). Study group (Group B) was weaned using a new protocol which consisted of formal daily wean assessments and one SBT at PSmin not to exceed 2 hours. Patients did not perform SBT's if they did not meet criteria for weaning. If a patient did not tolerate PSmin, they were returned back to previous vent settings for rest. If they passed the SBT, they were considered for extubation. For Both groups, PSmin levels were defined as: PS 6 for ETT >7.0mm,  PS 8 for ETT 7.0mm, PS 10 for ETT <7.0mm, or PS was titrated to achieve an overlapping Pressure/Volume Curve, with inspiration remaining on the outer right most portion of the curve. Rest settings incorporated the Pressure Control Mode, with Plateau Pressures ≤30cmH2O, and RR set at 70-80% of patient total rate, PEEP & FIO2 to achieve SPO2 ≥94%. Differences in mean and median ventilator length of stay (VLOS), and difference in re-intubation rates were the primary end points.  All ventilator patients were logged into a Microsoft Access Database (1998). This database was sent to our Data Analysis department for inference testing.

Result of the Wilcoxon Two-Sample Test suggests that the difference in VLOS among the groups is not statistically significant (p-value = 0.3213) with a predicting power of 81%. This result is supported by the Median Two-Sample Test (p-value = 0.3320), Van der Waerden Two-Sample Test (p-value = 0.3067) and Savage Two-Sample Test (p-value = 0.1354). Moreover, rates of re-intubation were compared between the groups. Results suggest that there is no significant difference between Group A and Group B (3% vs. 7%, p - value = 0.1432) at a = 0.05 level of significance.

  The new protocol with one weaning trial per day & no WP is as good as the standard protocol with two weaning trials per day & daily WP, but with a mean increase in VLOS of almost two days even though the median increase is a mere 0.38 days.  

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