Evaluation of a new thin-walled endotracheal tube for use in children

A new endotracheal tube for infants--laboratory and clinical assessment: a preliminary study

BACKGROUND

Conventional endotracheal pediatric tubes offer high resistance due to their small diameters and relatively high flow during ventilation. Any increase of the diameter of the tube lumen decreases the airway resistance and subsequently, the work of breathing (WOB). We compared ventilation mechanics using a new, cone-shaped endotracheal tube of our design to the Cole and standard tubes.

METHODS

The study has been divided into three parts: (i) preliminary laboratory tests, (ii) in vitro study with infant lung model, and (iii) clinical study in infants. Flow resistance and WOB were compared, using standard, Cole (in experimental phase only) and cone tubes.

RESULTS

We proved that inspiratory (Ri ) and expiratory (Re ) resistance, and WOB, were significantly lower in patients ventilated via a cone tube. Mean Ri decreased by 37%, compared with the baseline values, Re - by 35%, and total WOB - by 12%.

CONCLUSION

The cone tube offers lower resistance to gas flow than the standard, used nowadays in clinical practice. It can be especially beneficial to spontaneously breathing patients reducing WOB and improving gas exchange.

Predictors of successful extubation of preterm low-birth-weight infants with respiratory distress syndrome

OBJECTIVE

The aim of the study was to measure pulmonary mechanics in infants with respiratory distress syndrome before extubation and to correlate pulmonary function values with successful extubation.

DESIGN

Clinical study.

SETTING

Neonatal intensive care unit.

PATIENTS

Fifty-one infants (birth weight, 1158.6 +/- 150.6 g; gestational age, 29.1 +/- 2.0 wks).

INTERVENTIONS

Ventilation and daily ventilatory management.

MEASUREMENTS AND MAIN RESULTS

Of the 51 infants studied, 35 (60.8%) were successfully extubated, whereas 16 (39.2%) required reintubation and mechanical ventilation within 72 hrs after extubation. All patients met the clinical and biochemical criteria for extubation. Variables of artificial ventilation before extubation were minimal in all the studied cases (Fio(2) </=0.4, inspiratory pressure </=20 cm H(2)O, ventilatory rate, </=10/min). Pulmonary mechanics were measured before extubation using a noninvasive, mobile VenTrak measuring station.

RESULTS

Significant differences in pulmonary function values between the groups were found. Lower resistance of airways and work of breathing and higher dynamic compliance, tidal volume, and minute ventilation before extubation were associated with successful extubation.

CONCLUSION

On the average, tidal volume values of >6 mL/kg, minute ventilation of >309 mL/kg/min, work of breathing of <0.172 J/L, dynamic compliance of >/=1 mL/cm H(2)O/kg, and resistance of airways of </=176 cm H(2)O/L/sec predicted successful extubation. We recommend measurement of pulmonary function as an assessment tool in determining readiness for extubation.