Anaesthesia
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A multilumen catheter guide (jet stylet) with an adapter has been used for various manoeuvres in the upper airway. With the split length, procedures such as change of tracheal tube from oral to nasal nasal to oral position, are possible while the patient's lungs are ventilated by means of high frequency jet ventilation. During high frequency jet ventilation for longer periods of time, for example for microlaryngeal surgery, the central channel of the catheter is used as a conduit for jet delivery, whilst the other channels are used for continuous monitoring of airway pressure and concentration of carbon dioxide in the upper airway.
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We measured continuously cerebral venous oxyhaemoglobin saturation (SjvO2) using a 4F fibreoptic catheter in 11 patients scheduled for elective myocardial revascularisation. The aims of this study were to assess the Oximetrix 3 computer and Opticath 40 cm catheter during moderate hypothermic cardiopulmonary bypass, and identify epochs of cerebral hypoperfusion (SjvO2 < 54%). Radial artery pressure, brain electrical activity, arterial and cerebral venous oximetry (dual oximetry), end-tidal CO2 and nasopharyngeal temperature were recorded continuously in each patient. ⋯ In 10 patients SjvO2 decreased below normal at rewarming and myocardial reperfusion: mean lowest value 37%, range 19%-55%. Reduced SjvO2 were associated with a decrease in perfusion pressure (r = 0.292, 80 DF, p = 7.7* 10(-3)), and with an increase in nasopharyngeal temperature (r = -0.46, 115 DF, p = 2.7* 10(-7)) after moderate hypothermia. The Oximetrix 3 computer and Opticath 40 cm catheter provided reliable and accurate continuous monitoring of SjvO2 during nonpulsatile cardiopulmonary bypass involving hypothermia with haemodilution and identified rewarming as the period of greatest risk of global cerebral hypoperfusion.