Pressure-Support Ventilation Better for Weaning Trials

By Will Boggs MD

June 14, 2019

NEW YORK (Reuters Health) - Pressure-support appears to be better than T-piece ventilation for spontaneous-breathing trials, a randomized trial suggests.

Spontaneous-breathing trials (SBT) are used to evaluate the readiness of patients receiving mechanical ventilation for extubation and liberation from ventilatory support. Pressure-support ventilation (PSV) and T-piece ventilation lasting 30 minutes to two hours are the most common modes of SBT, but it remains unclear which is the optimal method.

Dr. Carles Subira of Althaia Xarxa Assistencial Universitaria de Manresa, in Spain, and colleagues at 18 intensive care units in that country compared two weaning strategies: one more demanding for patients (T-piece for two hours) versus one less demanding for patients (8-cm H2O PSV for 30 minutes).

Successful extubation (i.e., remaining free of mechanical ventilation 72 hours after the SBT) occurred in 473 patients (82.3%) in the PSV group and 428 patients (74%) in the T-piece group (P=0.001), the team reported June 11 in JAMA.

Significantly more patients were extubated after the first SBT in the PSV group (92.5%) than in the T-piece group (84.1%), with no difference in need for reintubation within the next 72 hours.

"These findings support the use of a shorter, less demanding ventilation strategy for SBTs," the researchers conclude.

The results are consistent with those of a 2014 Cochrane review comparing the two approaches (https://bit.ly/2KK7bLM).

The researchers also found that hospital mortality rates were significantly lower in the PSV group (10.4%) than in the T-piece group (14.9%, P=0.02), as was 90-day mortality (13.2% vs. 17.3%, P=0.04).

Dr. Timothy D. Girard of the University of Pittsburgh School of Medicine, in Pennsylvania, who co-authored an accompanying editorial, told Reuters Health by email, "Though exciting and intriguing, this result is surprising because it's not apparent why this would be the case. None of the other secondary outcomes seemed to be affected by the type of SBT used, so more research is needed to determine whether the mortality benefit is real and, if so, what mechanism underlies it."

"Given the size of the trial and its results, I anticipate that future guidelines will recommend the less demanding (30-minute PSV) SBT be used during a patient's first SBT," he said. "The trial, however, doesn't give us guidance about a subsequent SBTs after a patient fails their first SBT since such patients were no longer managed according to the trial protocol."

"We as critical-care clinicians need to proactively identify patients who are ready to be liberated from mechanical ventilation," Dr. Girard said. "This trial shows that shorter, less demanding SBTs are safe when first assessing a patient's readiness, so using a more demanding SBT at that time is not only unnecessary but potentially dangerous because it may inappropriately delay extubation."

Dr. Jan Friedrich from Saint Michael's Hospital and the University of Toronto, Canada, who has researched various SBT methods, told Reuters Health by email that the trial "strengthens the current weak recommendation to preferentially use pressure support rather than T-piece spontaneous-breathing trials."

"There may be select patients where clinicians may still want to use T-piece spontaneous breathing trials (which provide less support) in cases where the risks of reintubation are particularly high and the clinicians want to be more sure that the patient can be successfully extubated," he said. "However, there is a lack of randomized-controlled-trial evidence identifying any particular type of patient where such a strategy may be beneficial."

Dr. Kaweesak Chittawatanarat from Chang Mai University in Thailand, recently found T-piece ventilation to be superior to PSV SBT in a surgical ICU setting (https://bit.ly/2wRI2GE), told Reuters Health by email, "One concern for this study is the time for SBT is different between T-piece (120 min) and pressure support (30 min). This might lead the T-piece to have a higher failure rate."

Dr. Jose Augusto Pellegrini from Moinhos de Vento Hospital, in Porto Alegre, Brazil, has twice reviewed T-piece and PSV SBT techniques.

"The more demanding the SBT is, the more patients fail," he told Reuters Health by email. "However, this trial clarifies that, beyond making the extubation process more gentle, PSV did not result in more extubation failures."

"This is by far the largest study assessing this question, following strict methodology, providing robust results," he said. "I believe guidelines should reinforce confidence that PSV should be routinely used as a superior choice for assessing SBT tolerance."

Dr. Pellegrini cautioned, "I'm not sure these results apply to all patients. Difficult-to-wean patients, e.g., represent a completely different scenario."

Dr. Subira did not respond to a request for comments.

SOURCE: https://bit.ly/2X3oDRT

JAMA 2019.

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