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