March 13, 2023
3 min read
Knox reports receiving PhD program funding from The Saban Research Institute at Children’s Hospital Los Angeles. Please see the study for all other authors’ relevant financial disclosures. Alibrahim reports no relevant financial disclosures. Rotta reports receiving personal fees from Breas US for consulting and royalties from Elsevier.
Forty percent of children passing at the 30-minute mark of a spontaneous breathing trial to assess extubation readiness failed in the remainder of the trial, according to a study published in CHEST.
“A 30-min spontaneous breathing trial (SBT) based on our clinical and physiologic observations alone will miss many patients who go on to fail a 120-min SBT,” Kelby E. Knox, MS, of the department of anesthesiology and critical care medicine at Children’s Hospital Los Angeles, and colleagues wrote.
In a secondary analysis of an ongoing randomized controlled trial, Knox and colleagues analyzed 100 children (median age, 4.5 years; interquartile range, 1.6-12.6 years; 46% male) with acute respiratory distress syndrome on mechanical ventilation undergoing daily 120-minute SBTs to determine the reasons behind SBT failure. They also sought to find out if respiratory rate, tidal volume (VT) and rapid shallow breathing index (RSBI), assessed via spirometry, at the 30-minute mark of the trial could predict SBT passage using receiver operating characteristic plots and area under the curve (AUC).
Based on esophageal manometry for effort of breathing, researchers divided outcomes into three groups: passage, early failure ( 30 minutes) or late failure (30-120 minutes).
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Of the 305 SBTs collected from the total cohort, 42% passed, 32% failed within 30 minutes and 25% failed between 30 and 120 minutes.
Researchers found that 40% of the children who passed at 30 minutes failed by 120 minutes, and more than 80% of the failed SBTs had high respiratory effort based on esophageal manometry.
High pressure-rate product (PRP) was the most frequent reason for SBT failure found in 77% of the failed SBTs, according to researchers. Additionally, 60% of SBTs failed due to moderate or severe retractions; 16% failed due to high end-tidal carbon dioxide; and 15% or less failed due to desaturation, high RSBI, apnea or increased heart rate.
In terms of predicting SBT passage, researchers observed that values of respiratory rate, VT, RSBI, FiO2, oxygen saturation or capnography could not predict the final outcome when taken at the 30-minute mark. They noted that this result is likely due to the fact that these measures fail to capture the patients’ effort of breathing.
Predictors of SBT failure in a multivariable model included respiratory rate (P < .001), RSBI greater than 7 (P = .034), pre-SBT inspiratory pressure level (P = .009) and pre-SBT retractions (P = .042) in a derivation set of 212 SBTs; however, researchers reported that this model did not perform well in an independent validation set of 93 SBTs (AUC = 0.67).
Need for future studies
Lastly, extubation was attempted in every child. Researchers observed a 9% reintubation rate (within 48 hours) for those who had a successful SBT on extubation day and an 8% reintubation rate for those who had a failed SBT on extubation day.
“On the basis of these data, we believe SBTs of 2 hours, which incorporate a measure of work or effort of breathing (at minimum, clinical examination findings if not objective markers such as PRP), should be used in children recovering from ARDS,” Knox and colleagues wrote. “However, a large, multicentered randomized trial is needed to test the impact of such a strategy on extubation failure and length of ventilation.”
This study by Knox and colleagues confirms the 120-minute SBT is more useful but is not powered to determine the ideal SBT length as it relates to extubation outcome, as SBT passage does not ensure extubation success, Omar Alibrahim, MD, and Alexandre T. Rotta, MD, both of the department of pediatrics at Duke University’s School of Medicine and the division of pediatric critical care unit at Duke University Medical Center, wrote in an accompanying editorial.
“Considering the benefits of the performance of an SBT as part of an extubation readiness bundle and the lack of data comparing the effect of various durations of SBT on extubation success, it is reasonable to follow the current recommendation to conduct an SBT for at least 30 min, with longer duration trials (60 to 120 min) preferred for patients with higher risk of extubation failure (eg, neuromuscular weakness, diaphragm deconditioning, myocardial dysfunction) in whom demonstration of greater respiratory endurance is desirable prior to extubation,” Alibrahim and Rotta wrote.