Nonivasive assessment by capacitance respirometry of respiration before and after extubation

Respiration before and after extubation was studied in postoperative patients following weaning from respirator support. Changes in tidal and minute volume and respiratory flow rates were determined by capacitance respirometry, a noninvasive method of monitoring respiration. The presence of an endotracheal tube of 7.5 to 8.5 mm ID had no significant effect on ventilation, respiratory flow rates, or intrapulmonary shunting. Laboratory and clinical evidence showed that in postoperative patients, an endotracheal tube of 8 mm ID substitutes a relatively low, predictable resistance for a potentially excessive and variable upper airway resistance.