The Bicore pulmonary monitor. A device to assess the work of breathing while weaning from mechanical ventilation.

The Bicore CP-100 pulmonary monitor offers the advantage of continuous pulmonary monitoring at the bedside. Using an easily placed oesophageal balloon catheter and a flow transducer within the ventilator system, intrathoracic pressures, airway pressures and airway flow can be measured, and from these the Bicore calculates 25 other respiratory variables. The monitor screen displays real time waveforms of airway pressure, airway flow, oesophageal pressure and inspired tidal volume, and with these data it should be possible to determine more accurately when patients can be weaned from mechanical ventilation. It should also be possible to assess objectively the onset of respiratory fatigue and failure so that intervention can take place at an earlier stage. To assess the ease of use and potential benefit, the Bicore was used to calculate the work of breathing while weaning eight patients from mechanical ventilation in a spontaneous breathing mode. The pressure support ranged from 20 cmH2O, 10 cmH2O and 5 cmH2O, to a continuous positive airway pressure of 5 cmH2O, all with a positive end-expiratory pressure of 5 cmH2O, down to a single T-circuit with no positive airway pressure or end-expiratory pressure. The work of breathing while on a Veola Hamilton ventilator was found to be about the same, while receiving pressure support of 20 cmH2O compared to a continuous positive airway pressure of 5; the other forms of respiratory support increased the work of breathing significantly.