SAN DIEGO – When attempting a second extubation, improvements in weaning parameters, compared with the first extubation attempt, do not predict success. Instead, the best predictors were the values of the parameters immediately before the second attempt.
“We hypothesized that the change in parameter values was more important than the actual values right before we tried to re-extubate, and that didn’t turn out to be the case. Because it was a smaller study, we can’t say [change in values] is not useful at all, but we didn’t find a strong association. We showed that the magnitude of the effect with the number measured right before the re-extubation is probably your best bet, but you should obviously evaluate the whole clinical scenario,” commented senior author Michael David Maile, MD, assistant professor of anesthesiology at the University of Michigan, Ann Arbor.
The study was presented at the Critical Care Congress sponsored by the Society of Critical Care Medicine by Suraj Trivedi, MD, who is currently an anesthesiology fellow at Stanford (Calif.) Medicine.
Factors such as rapid shallow breathing index (RSBI), negative inspiratory force (NIF), vital capacity (VC), and partial pressure of arterial carbon dioxide (PaCO2) have been shown to predict success or failure of an initial extubation attempt.
There is currently little available guidance on how to proceed when a first extubation attempt fails. The researchers had anticipated that RSBI, NIF, VC, and PaCO2 levels matching the first attempt would be associated with success the second time around.
But their retrospective study of adult patients at the University of Michigan critical care units found that only the change in RSBI values predicted success on a univariate analysis, and that association became statistically insignificant once they corrected for baseline RSBI previous to the re-extubation attempt.
“I think the biggest take-home message is that we have to figure out each attempt to extubate on its own merits. If you’re trying to extubate a patient in the ICU who has potentially been intubated and extubated multiple times, the clinical gut feeling is always that [the patient has] to be better off than the previous attempt. What we are pointing out is that it really doesn’t matter. If the parameters are all within the overall guidelines, it’s still okay to extubate, even if the absolute change in the variables is not better [than the previous attempt],” Dr. Trivedi said in an interview.
“People put a lot of emphasis on the improvement from the first to the second attempt, and this should temper that enthusiasm to put a lot of weight on the change. But I don’t think our data support that the change means nothing,” added Dr. Maile.
The study included 525 patients (42% female). Comorbidities were common: 72% had cardiac arrhythmias, 58% had hypertension, 33% had renal failure, 39% had a pulmonary disorder, and 25% had liver disease.
Univariate analyses showed associations between values of parameters immediately before the second extubation attempt and success in the second extubation attempt, including RSBI (re-extubation success, mean 53.1 vs failure, mean 68.8; P =.0002) and NIF (success, mean –41.2 vs. failure, mean –38.4; P =.036), and VC (success, mean 1009.8 vs. failure, mean 906.8; P =.017).
When the researchers examined changes in parameters between the first and second attempt, only a change in RSBI predicted success (success, value change of 7.1 vs. failure, value change of 0.05; P less than .031). But when they corrected for the RSBI value immediately before the second attempt, the difference was not statistically significant (P = .892).
The study was not funded. Dr. Maile and Dr. Trivedi have no relevant financial disclosures.
SOURCE: Trivedi S et al. CCC48 2019, Abstract 27.