British journal of anaesthesia
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We describe an enclosed afferent reservoir (EAR) breathing system developed by Ohmeda and designed to operate efficiently in spontaneous and controlled ventilation. The efficiency of the system was evaluated by calculating the fractional utilization of fresh gas in 10 ASA I-III patients during anaesthesia with controlled ventilation. Maximum efficiency occurred when the minute ventilation to fresh gas flow ratio was greater than 1.5. ⋯ The minimum fresh gas flow for use during controlled ventilation was determined in another eight ASA I-III patients when the minute volume to fresh gas ratio was greater than 1.5. In view of an increased arterial to end-tidal carbon dioxide partial pressure difference in patients in the first part of the study (1.03 kPa), normocapnia was defined as an end-tidal carbon dioxide partial pressure of 4.3 kPa. Normocapnia was achieved with a mean fresh gas flow of 66 ml kg(-1) min(-1), while 70 ml kg(-1) min(-1) produced mild hypocapnia.
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Stellate ganglion injections were performed using methylene blue 20 ml in 20 cadavers before postmortem examination. There was spread of solution into the posterior mediastinum and over the apical pleura. There was no spread onto the thoracic sympathetic chain.
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A patient with a foreign body penetrating the neck and chest was found to have physical signs which were consistent with serious tracheal injury and included a large movement of air through the lower part of the neck. The subsequent management of the patient and the difficult problem of securing an airway are described. At operation, the tracheal damage was found to be less severe than anticipated and the observed air flow was a result of penetration of the foreign body into the pleural cavity. The management of the patient is discussed and the potential for misinterpretation of the physical signs in this type of trauma is emphasized.
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Randomized Controlled Trial Comparative Study Clinical Trial
Adrenaline, fentanyl or adrenaline and fentanyl as adjuncts to bupivacaine for extradural anaesthesia in elective caesarean section.
We have compared the effects of extradural fentanyl and fentanyl plus adrenaline with adrenaline alone as adjuncts to extradural bupivacaine in patients undergoing elective Caesarean section. Forty-five patients were allocated randomly to receive 0.45% bupivacaine 20 ml with adrenaline 4.5 micrograms ml-1, fentanyl 4.5 micrograms ml-1 or adrenaline plus fentanyl (4.5 micrograms ml-1 of each) as supplements. The main outcome measures were time to bilateral analgesia of T6 or higher, need for intraoperative analgesic supplements, observer rating of intraoperative analgesia and patient assessment of analgesia using a 10-cm visual analogue scale. ⋯ Two patients experienced respiratory depression after extradural fentanyl and were given naloxone. Two neonates were also given naloxone. Close supervision is therefore recommended in the early postoperative period when this technique is used.
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Comparative Study
The auditory steady state response during sufentanil anaesthesia.
The auditory steady state response (ASSR) is a sinusoidal evoked potential elicited by rapidly repeated auditory stimuli. The ASSR was recorded in eight patients during high-dose sufentanil anaesthesia for cardiac surgery in order to assess its usefulness as a measure of the level of consciousness. The electroencephalogram (EEG) was recorded for comparison. ⋯ The amplitude increased with early signs of awakening in the Intensive Care Unit. With few exceptions, changes in the simultaneously recorded EEG were similar to those of the ASSR. The ASSR deserves further evaluation as a tool for monitoring level of consciousness during high-dose opioid anaesthesia.