Feasibility of measuring oxygen tension in uterine cervix carcinoma.

Cellular hypoxia is a cause of radioresistance. The oxygen tension (pO2) in normal tissues and in tumours can be measured by polarography. In this feasibility study we have measured the tissue pO2 of 10 patients suffering from uterine cervix carcinoma, using the Eppendorf histograph. The measurements were performed at the time of the brachytherapy after external radiotherapy. The machine was found to be reliable and no adverse effect was noted. The mean pO2 values in tumours were lower than those of normal tissues.

[The pinch-off syndrome: main cause of catheter embolism]. / Le syndrome de la pince costoclaviculaire: principale cause d'embolie de cathéter.

OBJECTIVE: To assess the incidence of the pinch-off syndrome (POS) in catheter fracture and embolism. STUDY DESIGN: Retrospective clinical study. PATIENTS: The medical files of 56 patients who had since 1989 an embolized fragment or entire catheter removed by an interventional radiologic procedure have been retrospectively analysed. METHODS: A POS was considered the causative factor when a chest X-ray showed a rupture of the catheter at the site of the costoclavicular space. RESULTS: From 1989 to the end of 1996, 56 catheter embolisms by fracture or disconnection occurred in our institution. The rupture from a POS was the main cause of embolism (24 patients out of 56). The incidence was 8/1000 of implanted ports inserted via a subclavian access [95% confidence interval: 4/1000-13/1000]. Preliminary clinical or radiologic signs of pinching existed in 50% of POS: difficult insertion, radiologic compression aspect, arm or shoulder pain, infusion rate and/or reflow depending on arm position. CONCLUSIONS: POS was the first cause of catheter embolism and should suggest the use of an alternative way for insertion instead of the subclavian access. When a catheter is inserted via a subclavian route, clinical and/or radiologic signs of POS require its removal.

Carbon dioxide monitoring during high frequency jet ventilation for direct laryngoscopy.

To improve ventilation monitoring during direct laryngoscopy, we have developed a high frequency jet ventilator which allows the aspiration of tracheal gas for carbon dioxide analysis (PtCO2) through the injector after stopping the ventilator. In 41 patients undergoing direct laryngoscopy, PaCO2 and PtCO2 were measured simultaneously during high frequency jet ventilation under general anaesthesia. PtCO2 and PaCO2 correlated significantly (r = 0.88), but PtCO2 underestimated PaCO2 by 0.84 (SD 0.72) kPa. The arterial to tracheal PCO2 difference was influenced by airway obstruction.

Measurement of end-expiratory pressure during transtracheal high frequency jet ventilation for laryngoscopy.

An anaesthetic technique using high frequency jet ventilation has been proposed for direct laryngoscopy, but this may expose the patients to the risk of barotrauma. In order to assess this risk, we have measured end-expiratory airway pressure (EEP) through the injector using two three-way solenoid valves mounted in series. At the end of insufflation the first valve was switched off and the apparatus deadspace connected to atmosphere through a large exit port during an adjustable time (decompression time). Then the second valve was switched off and the injection line connected to a transducer, allowing measurement of EEP through the injector. The accuracy of this measurement was tested against airway pressure measured directly in the trachea (Pt) in a lung model. Provided that the decompression time was long enough (70 ms) and the apparatus deadspace was small (6 ml), the difference between EEP and Pt was less than 1 cm H2O for frequencies up to 5 Hz. A clinical evaluation was performed in 64 patients under general anaesthesia before laryngoscopy. EEP correlated with end-expiratory pulmonary volume above apnoeic FRC inferred from abdominal and thoracic displacements. At jet frequencies up to 5 Hz, the correlations between these two variables were satisfactory (r greater than 0.88), suggesting that EEP is a good indicator of pulmonary overdistension.