Abstract
BACKGROUND: Tracheal gas insufflation (TGI) reduces arterial carbon dioxide tension (P(aCO2)) when used in conjunction with mechanical ventilation, but antegrade TGI flow increases intrinsic positive end- expiratory pressure (auto-PEEP) or end-expiratory lung volume (EELV). Tracheal gas exsufflation (TGE) might reduce TGI-elevated EELV while retaining the CO2 elimination effects of TGI. METHODS: An apparatus was designed to control TGI and/or TGE during selected portions of expiration. The first phase of the study examined the general effects of expiratory TGI and TGE on EELV and CO2 elimination in a mechanical test lung. In the second phase, effects on normal physiology were tested in uninjured dogs. Changes in EELV were measured by respiratory inductance plethysmography, and P(aCO2) was continuously monitored. TGI and TGE were applied separately and in combination during all or half of the expiratory phase. TGI/TGE combinations found to be most effective at CO2 elimination in the test lung model were applied in the animal tests. RESULTS: TGI raised EELV and TGE lowered EELV in both models, and exerted their greatest effects on EELV in the latter half of expiration. In the animal model, the TGI/TGE interventions tested reduced P(aCO2) by 16-32% (p < 0.01) compared to baseline P(aCO2), similar to or greater than reported clinical studies. CONCLUSIONS: Combining TGI and TGE allowed precise control of EELV in both models. Second-half TGI provided the most effective CO2 elimination.
Original language | English (US) |
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Pages (from-to) | 918-924 |
Number of pages | 7 |
Journal | Respiratory care |
Volume | 44 |
Issue number | 8 |
State | Published - Aug 1999 |
Keywords
- Auto-PEEP
- CO elimination
- Lung model
- Tracheal gas exsufflation
- Tracheal gas insufflation