The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

Rapid Shallow Breathing Index - A Key Predictor for Non-Invasive Ventilation

John Crawford RRT, Ronny Otero MD, Michael Donnino MD,
Rula Khazal RRT (Associate), Tami Lenior RRT (Associate), Nikolai Pamukov RRT
Henry Ford Hospital, Detroit, Michigan

 

Background:  Yang et.al. and Tobin et. al. first described the Rapid Shallow Breathing Index (RSBI) as the most accurate predictor of failure to weaning patients from mechanical ventilation when compared to the Compliance, Resistance, Oxygenation and Pressure index (CROP) Index. The RSBI is the ratio determined by the frequency (f) divided by the tidal volume (VT). An RSBI ≤ 105 has been widely accepted by healthcare professionals and integrated into most mechanical ventilation weaning protocols. One of the recommendations from the International Consensus Conferences in Intensive Care Medicine: Noninvasive Positive Pressure Ventilation in Acute Respiratory Failure is healthcare providers need to have the means of rapidly identifying patients who will improve in response to Non-Invasive Ventilation (NIV). Hence, we hypothesized that the converse of using the RSBI for weaning might be useful in predicting the need for non-invasive ventilation. Advancements in technology have made it easier to accurately attain bedside RSBI measurements. The goal of this study was to ascertain a threshold value of RSBI that could predict the need for Non-Invasive Ventilation (NIV) in patients presenting with acute respiratory distress to the critical care area (Category One) in the emergency department (ED).

Methods:
  This was a blinded, observational cohort trial that was approved by the Henry Ford Hospital Institutional Review Board. Henry Ford Hospital is an urban, teaching institution in Detroit, Michigan with an emergency department census of 95,000 patient visits per year.  Inclusion Criteria: Patients > 18 years of age triaged to category one (CAT 1) with acute respiratory distress and for whom the decision to intubate, use of NIV or discharge of the patient had not been decided. Exclusion Criteria: Immediate intubation, NIV, or discharged from the CAT 1.  Baseline demographics and vital signs were collected prior to the initiation of the trial. The CO2SMO Plus!T with the ETCO2/Flow sensor was used for obtaining bedside measurements. Patients would breathe through the ETCO2/Flow sensor for 60 seconds with nose clips.

Results:
The threshold value for RSBI that discriminated best between no NIV and the need for NIV was determined in 61 patients. Thirty-five patients did not require ventilatory support had a mean RSBI of 105, twenty-six required NIV had a mean RSBI 222 (p=0.0001).  A receiver-operating-characteristic (ROC) curve was constructed based upon the data set in increments of 10 for the RSBI. An RSBI of ≥120 yielded the highest sensitivity and specificity for determining the need for non-invasive ventilation.

Conclusion:
  A Rapid Shallow Breathing Index of 120 or greater, as reflected by f/VT ratio, may be a predictor of when non-invasive ventilation support should be considered. Further prospective, randomized studies are needed to validate the value of 120.

1.   Yang KL, Tobin MJ. A prospective study of indexes predicting the outcome of trials of weaning from     

      mechanical ventilation. N Engl J Med 1991;324:1445-1450

2.   Pierson JD. Indications for mechanical ventilation in adults with acute respiratory failure. Respir Care          

      2002;47 (3):249-262

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