Tracheal gas insufflation during late exhalation efficiently reduces PaCO2 in experimental acute lung injury

Christopher Carter, Alexander B. Adams, Mary Stone, Peter Bliss, John R. Hotchkiss, John J. Marini

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Objective: Tracheal gas insufflation (TGI) reduces PaCO2 by flushing the tracheal and mechanical deadspace, and may have its maximum benefit when TGI gas is unopposed by significant expiratory gas flow. Thus, limiting TGI to the late expiratory period may diminish tracheal exposure to TGI gas while preserving the efficacy of TGI. This study examined the gas exchange consequences of such late-expiratory TGI. Design and setting: Randomized controlled trial, animal study. Materials: Eleven pigs. Interventions: After stable lung injury was established using oleic acid 11 pigs were ventilated using a standardized lung protective strategy. Phasic expiratory TGI was applied for 30 min stages during the last 20%, 40%, 60%, and 100% of expiration in random sequence. PaCO2 was continuously measured via an indwelling blood gas analysis system. Measurements and results: PaCO2 at baseline was 86.1±4.7 mmHg, and decreased progressively with increasing TGI duration of 20%, 40%, and 60%, but not 100%, of expiration (PaCO2=75.7±5.2, 68.8±3.6, 65.1±5.3 and 65.2±5.2 mmHg, respectively). For all stages the reduction in PaCO2 relative to baseline was significant. Trends of increasing PaO2 and airway pressure with increasing TGI duration were noted and most likely associated with a TGI-induced increase in lung volume. Conclusions: Under these conditions confining TGI to the final 60% of expiration achieved effective PaCO2 reduction, not significantly different from panexpiratory TGI, while limiting exposure of the trachea to TGI gas, and reducing the potential for TGI-induced hyperinflation. These findings suggest that TGI is most effectively applied in a phasic manner in late expiration, with its duration titrated to effect.

Original languageEnglish (US)
Pages (from-to)504-508
Number of pages5
JournalIntensive Care Medicine
Issue number4
StatePublished - 2002
Externally publishedYes

Bibliographical note

Funding Information:
Received: 26 March 2001 Accepted: 6 December 2001 Published online: 1 February 2002 © Springer-Verlag 2002 This work was supported by NIH SCOR N-071. J.R.H. is supported by American Heart Association grant SDG9301184N


  • Insufflation, trachea
  • Lung Injury
  • Pulmonary gas exchange
  • Respiration, artificial
  • Respiratory distress syndrome, adult


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