RSBI Rate - Not only RSBI !
The Rapid Shallow Breathing Index (RSBI) remained an integral part of ventilator weaning parameter. Dr. Segal and coll. from Morristown Memorial Hospital, NJ went one step forward and looked into "RSBI Rate" (rate of change in the RSBI) with the question that as respiratory failure is a dynamic phenomenon - should serial followup of RSBI would be a more accurate predictor of weaning outcome, instead of one RSBI at a given time ?. In a prospective cohort study, patients with following criteria has been included:
- requiring mechanical ventilation for more than 48hrs,
- ET tube size no smaller than 7.5 in the ICU,
- cleared by an intensivist (independent of study investigators) as an appropriate candidate to undergo weaning,
- on hospital respiratory therapist driven weaning protocol.
Spontaneous Breathing Trial (SBT) for up to two hours given and parameters were measured periodically at SBT. The RSBI Rate was calculated by the formula:
RSBI rate: (RSBI2 - RSBI1)/ RSBI1 × 100Out of 30 patients, 21 were successfully extubated, 3 were re-intubated within 24 hours and six were intolerants to the SBT. The RSBI on the failure plus Intolerance group was 40.2 (SD 14.7) but RSBI rate on every patient that failed or had intolerance to SBT had a RSBI Rate greater that 20%. It was concluded that the RSBI Rate less that 20% has a sensitivity of 90.4% and specificity of 100% in predicting weaning success.
USE OF THE RATE OF CHANGE OF THE RSBI DURING SPONTANEOUS BREATHING TRIAL AS AN ACCURATE PREDICTOR OF WEANING OUTCOME - Critical Care Medicine: Volume 33(12) Abstract Supplement December 2005 p A20