This week’s Pulm PEEPs Pearls episode is all about spontaneous breathing trials (SBTs). SBTs are a standard part of the daily practice in the intensive care unit, but the exact methods vary across ICUs and institutions. Listen in to hear about the most common methods of SBTs, the physiology of each method, and what the evidence says.
This episode was prepared with research by Pulm PEEPs Associate Editor George Doumat.
Dustin Latimer, another Pulm PEEPs Associate Editor, assisted with audio and video editing.
What an SBT is really testingAn SBT is a stress test for post-extubation work of breathing, not just a ventilator check.The goal is to balance sensitivity and specificity:Too hard → unnecessary failures and delayed extubationToo easy → false positives and higher risk of reintubation Common SBT modalities and how they compareT-pieceNo inspiratory support and no PEEPHighest work of breathingMost “physiologic” but often too strictPressure support (PS) + PEEP (e.g., 5/5 or 8/5)Offsets ETT resistance and provides modest assistanceEasier to pass than T-pieceCPAP (0/5)No inspiratory help, but provides PEEP to counter ETT resistanceSits between PS and T-piece in difficulty Evidence favors pressure-supported SBTs for most patientsLarge meta-analysis (~6,000 patients, >40 RCTs):Pressure-supported SBTs increase successful extubation (~7% absolute benefit)No increase in reintubation ratesTrials (e.g., FAST trial):Patients pass SBTs earlierLeads to earlier extubation and fewer ventilator-associated risksBottom line: A 30-minute PS 5/5 SBT is evidence-based and appropriate for most stable ICU patients When a T-piece still makes senseT-piece SBTs are useful when:
Cost of reintubation is highDifficult airwayPrior failed extubationPretest probability of success is lowProlonged or difficult weaningTracheostomy vs extubation decisionsNeed to mimic physiology without positive pressureIn LV dysfunction or pulmonary edema even small amounts PEEP may significantly improve physiologySome centers use a hybrid approach: PS SBT → short confirmatory T-piece before extubation CPAP as a middle groundRationale:Allows full patient effort while compensating for ETT resistanceEvidence:Fewer and smaller trialsPossible modest improvement in extubation successNo clear mortality or LOS benefitReasonable option based on patient physiology, institutional protocols, and clinician comfort No single “perfect” SBT modeAcross PS, T-piece, CPAP, and newer methods (e.g., high-flow via ETT) there are no consistent differences in mortality or length of stayWhat matters most:Daily protocolized screeningThoughtful bedside clinical judgmentMatching SBT difficulty to patient-specific risk Institutional variation is normal—and acceptableExamples:PS 10/5 in postoperative surgical ICU patientsPS 5/0 as an intermediate difficulty optionKey question clinicians should ask: What does passing or failing this specific SBT tell me about this patient’s likelihood of post-extubation success? Take-home pearlsSBTs are stress tests of post-extubation physiology.PS 5/5 for 30 minutes is a strong default for most ICU patients.T-piece trials are valuable when false positives are costly or physiology demands it.CPAP is reasonable but supported by less robust data.Consistency, daily screening, and judgment matter more than the exact mode.References and Further Reading
Burns KEA, Khan J, Phoophiboon V, Trivedi V, Gomez-Builes JC, Giammarioli B, Lewis K, Chaudhuri D, Desai K, Friedrich JO. Spontaneous Breathing Trial Techniques for Extubating Adults and Children Who Are Critically Ill: A Systematic Review and Meta-Analysis. JAMA Netw Open. 2024 Feb 5;7(2):e2356794. doi: 10.1001/jamanetworkopen.2023.56794. PMID: 38393729; PMCID: PMC10891471.Burns KEA, Sadeghirad B, Ghadimi M, Khan J, Phoophiboon V, Trivedi V, Gomez Builes C, Giammarioli B, Lewis K, Chaudhuri D, Desai K, Friedrich JO. Comparative effectiveness of alternative spontaneous breathing trial techniques: a systematic review and network meta-analysis of randomized trials. Crit Care. 2024 Jun 8;28(1):194. doi: 10.1186/s13054-024-04958-4. PMID: 38849936; PMCID: PMC11162018.Subirà C, Hernández G, Vázquez A, Rodríguez-García R, González-Castro A, García C, Rubio O, Ventura L, López A, de la Torre MC, Keough E, Arauzo V, Hermosa C, Sánchez C, Tizón A, Tenza E, Laborda C, Cabañes S, Lacueva V, Del Mar Fernández M, Arnau A, Fernández R. Effect of Pressure Support vs T-Piece Ventilation Strategies During Spontaneous Breathing Trials on Successful Extubation Among Patients Receiving Mechanical Ventilation: A Randomized Clinical Trial. JAMA. 2019 Jun 11;321(22):2175-2182. doi: 10.1001/jama.2019.7234. Erratum in: JAMA. 2019 Aug 20;322(7):696. doi: 10.1001/jama.2019.11119. PMID: 31184740; PMCID: PMC6563557.Burns KEA, Wong J, Rizvi L, Lafreniere-Roula M, Thorpe K, Devlin JW, Cook DJ, Seely A, Dodek PM, Tanios M, Piraino T, Gouskos A, Kiedrowski KC, Kay P, Mitchell S, Merner GW, Mayette M, D’Aragon F, Lamontagne F, Rochwerg B, Turgeon A, Sia YT, Charbonney E, Aslanian P, Criner GJ, Hyzy RC, Beitler JR, Kassis EB, Kutsogiannis DJ, Meade MO, Liebler J, Iyer-Kumar S, Tsang J, Cirone R, Shanholtz C, Hill NS; Canadian Critical Care Trials Group. Frequency of Screening and Spontaneous Breathing Trial Techniques: A Randomized Clinical Trial. JAMA. 2024 Dec 3;332(21):1808-1821. doi: 10.1001/jama.2024.20631. PMID: 39382222; PMCID: PMC11581551.Mahul M, Jung B, Galia F, Molinari N, de Jong A, Coisel Y, Vaschetto R, Matecki S, Chanques G, Brochard L, Jaber S. Spontaneous breathing trial and post-extubation work of breathing in morbidly obese critically ill patients. Crit Care. 2016 Oct 27;20(1):346. doi: 10.1186/s13054-016-1457-4. PMID: 27784322; PMCID: PMC5081985.Yi LJ, Tian X, Chen M, Lei JM, Xiao N, Jiménez-Herrera MF. Comparative Efficacy and Safety of Four Different Spontaneous Breathing Trials for Weaning From Mechanical Ventilation: A Systematic Review and Network Meta-Analysis. Front Med (Lausanne). 2021 Nov 22;8:731196. doi: 10.3389/fmed.2021.731196. PMID: 34881255; PMCID: PMC8647911.