A workable alternative to the problems with tracheal gas insufflation?

Suctioning through a double-lumen endotracheal tube helps to prevent alveolar collapse and to preserve ventilation

OBJECTIVE

Endotracheal suctioning can cause alveolar collapse and impede ventilation. One reason is the gas flow through a single-lumen endotracheal tube (ETT) provoking a gradient between airway opening and tracheal (P(tr)) pressures. Separately extending the patient tubing limbs of a suitable ventilator into the trachea via a double-lumen ETT should maintain P(tr). Can this technique reduce the side effects?

DESIGN AND SETTING

Bench and animal studies in a university hospital laboratory.

INTERVENTIONS

A lung model was ventilated via single and double-lumen ETTs. Closed-system suctioning was applied with catheters introduced into the single-lumen ETT or the expiratory lumen of the double-lumen ETT via swivel adapter. Seven anesthetized pigs (lungs lavaged) underwent three runs of ventilation and suctioning through (a, b) an 8.0-mm ID single-lumen ETT, (c) a double-lumen ETT (41Ch outer diameter, OD). In (a) the single-lumen ETT was disconnected for suctioning, in (b) and (c) ventilator mode was set to continuous positive airway pressure mode, and the ETTs remained connected.

MEASUREMENTS AND RESULTS

Bench: Suction through single-lumen ETTs impaired ventilation and led to strongly negative P(tr) (common: -10 to -20 mbar); the double-lumen ETT technique maintained ventilation and pressures.

ANIMALS

Lung gas content (computed tomography, n=4) and arterial oxygen partial pressure, initially 1462+/-65 ml/532+/-76 mmHg, were significantly reduced by suctioning through single-lumen ETT: to 302+/-79 ml/62+/-6 mmHg with disconnection and to 851+/-211 ml/158+/-107 mmHg with closed suction. With double-lumen ETT they remained at 1377+/-95 ml/521+/-56 mmHg.

CONCLUSIONS

The double-lumen ETT technique minimizes side effects of suctioning by maintaining P(tr).

Tracheal double-lumen ventilation attenuates hypercapnia and respiratory acidosis in lung injured pigs

OBJECTIVE

Evaluation of ventilatory and circulatory effects with coaxial double-lumen tube ventilation for dead-space reduction as compared with standard endotracheal tube ventilation.

DESIGN

Experimental study in a pig model of lung lavage induced acute lung injury.

SETTING

University research laboratory.

MEASUREMENTS AND RESULTS

Tidal volumes of 6, 8 and 10 ml/kg body weight with a set respiratory rate of 20 breaths per minute were used in a random order with both double-lumen ventilation and standard endotracheal tube ventilation. Measurements of ventilatory and circulatory parameters were obtained after steady state at each experimental stage. With a tidal volume of 6 ml/kg, PaCO(2) was reduced from 10.9 kPa (95% CI 9.0-12.9) with a standard endotracheal tube to 8.2 kPa (95% CI 7.0-9.4) with double-lumen ventilation. This corresponds to a reduction in carbon dioxide levels by 25%. At 6 ml/kg, pH increased from 7.17 (95% CI 7.09-7.24) with a standard endotracheal tube to 7.27 (95% CI 7.21-7.32) with double-lumen ventilation. Tracheal pressure was monitored continuously and no difference between single- or double-lumen ventilation was noted at corresponding levels of ventilation. There was no formation of auto-PEEP. Partial tube obstruction due to secretions was not observed during the experiments.

CONCLUSIONS

Coaxial double-lumen tube ventilation is an effective adjunct to reduce technical dead space. It attenuates hypercapnia and respiratory acidosis in a lung injury pig model.