Arch Dis Child Fetal Neonatal Ed 98:F70-F73 doi:10.1136/fetalneonatal-2011-301340
  • Original articles

Variability of respiratory parameters and extubation readiness in ventilated neonates

  1. Guilherme M Sant'Anna
  1. 1Department of Neonatology, McGill University, Montreal, Canada
  2. 2Division of Newborn Services, Royal Women's Hospital, Melbourne, Australia
  3. 3Neonatal Consultant, Cambridge, UK
  4. 4Department of Pediatrics, Mcgill University Health Center, Montreal, Canada
  1. Correspondence toGuilherme M Sant'anna, Mcgill University Health Center, Department of Pediatrics, 2300 Tupper Street, Room C-912, Montreal, Quebec H3H1P3, Canada; guilherme.santanna{at}
  1. Contributors Dr. Morley, Dr. Sant'Anna and Jennifer Kaczmarek generated the concept for this investigation. Dr. Kamlin, Dr. Morley and Dr. Davis completed the original investigation that generated the data used in the present manuscript. Jennifer Kaczmarek performed the data analysis and compiled the results. Jennifer Kaczmarek and Dr. Sant'Anna wrote the manuscript, with input from Dr. Kamlin, Dr. Davis and Dr. Morley.

  • Received 8 November 2011
  • Accepted 15 March 2012
  • Published Online First 3 May 2012


Background A spontaneous breathing trial (SBT) has been used to guide suitability of extubation in VLBW infants. Respiratory variability (RV) has been used to assess extubation readiness in adults but was never investigated in preterms. The combination of a SBT and RV may further improve prediction of successful extubation.

Study design Using data previously collected during the SBT, the following respiratory variables were analysed: inspiratory time (TI), expiratory time (TE), TI/total breath time, tidal volume (VT) and mean inspiratory flow (VT/TI). RV was quantified using time-domain analysis for each respiratory variable and expressed as a variability index (VI). The sensitivity, specificity, positive and negative predictive values (PPV and NPV) of the SBT, each VI and combined SBT+VI were calculated. Extubation failure was defined as need of re-intubation within 72 h.

Results A total of 44 infants were included. Successfully (n=36) and unsuccessfully (n=8) extubated infants had similar baseline characteristics and number of breaths analysed. VI for VT/TIwas significantly decreased in the failure group. The combination of the SBT and VI of either TIor VTwere the most accurate predictors of successful extubation with a sensitivity of 100% and specificity of 75% and a PPV and NPV for extubation success of 95% and 100%, respectively.

Conclusions A significant decrease in VT/TIvariability occurred in infants requiring re-intubation. The combination of a SBT failure and decreased variability in TIor VTwas highly predictive of failure. This combination is promising but requires prospective evaluation in a larger population.


  • Funding JK was supported by scholarship and GSA received start-up funds from the Research Institute of the McGill University Health Center for this research.

  • Competing interests None.

  • Ethics approval Human Research Ethics Committee at the Royal Women's Hospital, Melbourne, Australia.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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