Higher End-Tidal Alveolar Dead Space Fraction Is Associated With Spontaneous Breathing Trial Failure

Tuesday, March 24, 2026

11:15 AM - 12:15 PM Central Time

Location: Connections Central - RST 03

DR

Debra J. Rosenbaum, MD

Childrens Hospital Los Angeles

Disclosure(s): No relevant financial relationship(s) to disclose.
IL

Ian Lovern, MD

Pediatric Critical Care Fellow
Children's Hospital Los Angeles

Disclosure information not submitted.
HL

Hayden Leeds, MD

Pediatric Critical Care Fellow
Children's Hospital Los Angeles

Disclosure information not submitted.
EW

Emma I. Whiteley, MD

Pediatric Resident
Children's Hospital Los Angeles, California

Disclosure information not submitted.
MK

Margaret J. Klein, MS

Senior Statistician
Children's Hospital Los Angeles

Disclosure information not submitted.
BO

Bashira A. Oloso, MS

Biostatistician
Children's Hospital Los Angeles

Disclosure information not submitted.
JH

Justin Hotz, BSRT, RRT-NPS

Software Engineer, Respiratory Therapist
Children's Hospital Los Angeles, California

Disclosure information not submitted.
KK

Kelby Knox, PhD

Biomedical Engineer
Medtronics Diabetes, Northridge, CA

Disclosure information not submitted.
JK

Jeni Kwok, JD

Senior Research Associate
Children's Hospital Los Angeles, California

Disclosure information not submitted.
JB

Jennifer E. Bonilla-Cartagena, BA

Program Specialist
Children's Hospital Los Angeles, California

Disclosure information not submitted.
DB

David A. Baron, MS

Research Associate
Children's Hospital Los Angeles, California

Disclosure information not submitted.
KK

Kristen Kohler, RCP

Respiratory Care Partner
Childrens Hospital Los Angeles

Disclosure information not submitted.
DB

Dinnel Bornstein, RCP

Respiratory Care Partner
Children's Hospital Los Angeles, California

Disclosure information not submitted.
DC

Daniel Chang, RCP

Respiratory Care Partner
Children's Hospital Los Angeles, California

Disclosure information not submitted.
KV

Kennedy Vu, RCP

Respiratory Care Partner
Children's Hospital Los Angeles, California

Disclosure information not submitted.
AA

Anabel Armenta-Quiroz, RCP

Respiratory Care Partner
Children's Hospital Los Angeles, California

Disclosure information not submitted.
CN

Christopher J.L. Newth, MD

Research Director; Professor of Pediatrics
Children's Hospital Los Angeles, California

Disclosure information not submitted.
RK

Robinder Khemani, MD, MS (he/him/his)

Childrens Hospital Los Angeles, California

Disclosure information not submitted.
AB

Anoopindar K. Bhalla, MD

Associate Professor of Pediatrics
Children's Hospital Los Angeles, California

Disclosure information not submitted.

Introduction: We aimed to evaluate whether higher end-tidal alveolar dead space fraction (AVDSf) is associated with failure of a protocolized spontaneous breathing trial (SBT) in mechanically ventilated children with pediatric acute respiratory distress syndrome (PARDS). Secondary aims were determining whether children with high AVDSf were more likely to fail earlier in the SBT, or fail with hypercarbia, than children that failed with low AVDSf. Characterizing these relationships may offer insight into distinct phenotypes of SBT failure, potentially differentiating between ventilatory and non-ventilatory barriers to weaning.

Methods: Secondary analysis of a single-center randomized control trial evaluating lung and diaphragm protective ventilation in PARDS (R01 HL134666). Patients with severe acute neurologic injury were excluded. Both intervention and control groups underwent daily protocolized SBTs upon meeting predefined oxygenation criteria, with SBT failure defined by standardized criteria. Patients were studied until they passed an SBT. All patients had continuous end-tidal CO2 (PETCO2) monitoring. Pre-SBT AVDSf was calculated using median values from the 12 hours prior to the SBT: AVDSf=(PCO2-PETCO2)/PCO2. We evaluated the association between AVDSf and SBT failure, early SBT failure ( < 30 min) versus later failure (30-120 min), and failure related to hypercarbia (high PETCO2).

Results: There were 553 SBTs from 199 distinct patients with required data for analysis. Median age was 4.5 years (IQR 1.2-12.0); 38.2% had chronic lung disease. Median oxygenation index (OI) at randomization was 7.7 (IQR 4.8-13.0). Of 324 failed SBTs, 57.4% were early failures and 19.1% failed with hypercarbia. A one standard deviation increase in AVDSf was associated with increased odds of SBT failure [OR 1.33 (95% CI 1.08-1.65), p=0.0074] and remained significant [OR 1.27 (95% CI 1.02-1.58), p=0.032] after adjusting for age, PRISM III score, and median pre-SBT OI in multivariable mixed effects logistic regression modeling. AVDSf was not more associated with early SBT failure than late failure, or failure related to hypercarbia.

Conclusions: Higher AVDSf is independently associated with SBT failure regardless of failure phenotype. AVDSf may be an important marker to evaluate at bedside when assessing extubation readiness.