9. Spontaneous Ventilation
9. Spontaneous Ventilation
The Tulip has a large diameter breathing tube with low resistance to spontaneous breathing so it allows good oxygenation and CO2 elimination with good tidal volumes during spontaneous ventilation. The Tulip also has a large low pressure balloon-cuff that establishes a strong, competent seal for intermittent manual ventilation of the Patient to higher levels than is usually required (>20cmH2O). Manual ventilation without a leak is easily established once the Tulip cuff is inflated to match the ventilating pressure required. Normal ventilation pressures (+/-20cmH2O) can usually be established whilst running intra-cuff pressures of approximately +/-40mmHg (+/-54cmH2O).
It is important that the Patient is oxygenated at all times, and that an acceptable depth of anaesthesia is maintained at all times, particularly during transfer. Such maintenance of anaesthesia prevents unwanted responses to the introduction of, and presence of an anaesthetic airway. Should any coughing or straining occur, then it is recommended that the patent airway remain in-situ, and that the depth of anaesthesia be increased using bolus Propofol. The same result may be achieved by increasing the volatile dose administered, by increasing the vapourizer settings, or by increasing respiratory rate or tidal volume. Retention of the airway maximizes oxygenation, anaesthetic depth and airway control, and reduces reflex stimulation provoked by removal of the device.
Initially it may be difficult to ventilate the lungs, but this is frequently associated with glottic closure and chest wall rigidity, both secondary to inadequate depth of anaesthesia. These problems may almost always be overcome by patient, gentle ventilation with an anaesthetic volatile/gas/oxygen mix to increase the depth of anaesthesia.
Similar problems may be caused by surgical stimulation and other reflex arcs, and the same treatment is recommended, so as to deepen anaesthesia and suppress oropharyngeal reflexes. If the cuff leaks, and ventilating pressures are inadequate, this may be for several reasons.
