Inter-observer agreement of spontaneous breathing trial outcome

Spontaneous breathing trials (SBTs) are a very important test in the weaning process. The trial involves evaluation of multiple objective and subjective variables. These characteristics could lead to variability in interpreting outcomes with important clinical implications. We aimed to measure the inter-observer agreement between respiratory therapists when analyzing SBT outcomes.

In the context of a respiratory therapist-driven weaning protocol, 2 respiratory therapists independently interpreted the subjective variables (use of accessory muscles, agitation, and diaphoresis) and the overall outcome of SBTs (success vs failure) performed in adult subjects mechanically ventilated for any duration. Raw agreements between respiratory therapists and kappa statistics were calculated.

One-hundred fifty-one SBTs were interpreted. The overall trial outcome raw agreement was 93.3% (95% CI 88.2-96.3) and kappa 0.63 (95% CI 0.47-0.79). Raw agreement for subjective variables ranged between 92.1% (agitation) and 99.3% (diaphoresis). The group with disagreements in overall trial outcome had higher breathing frequency, breathing-frequency-to-tidal-volume ratio, and systolic blood pressure prior to the trial.

Within a respiratory therapist-driven weaning protocol, we found a near 90% inter-observer agreement in the interpretation of SBT outcomes. Our findings illustrate the complexity of interpreting fluctuating subjective and objective variables and their integration into one result: SBT success versus failure. Refining the definitions of variables and their limits for failure along with education might reduce this variability.