Canadian journal of anaesthesia = Journal canadien d'anesthésie
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In the last decade, capnography has developed from a research instrument into a monitoring device considered to be essential during anaesthesia to ensure patient safety. Hence, a comprehensive understanding of capnography has become mandatory for the anaesthetist in charge of patients in the operating room and in the intensive care unit. This review of capnography includes the methods available to determine carbon dioxide in expired air, and an analysis of the physiology of capnograms, which are followed by a description of the applications of capnography in clinical practice. ⋯ Physiological factors leading to changes in end-tidal carbon dioxide are discussed together with the clinical uses of this measurement to assess pulmonary blood flow indirectly, carbon dioxide production and adequacy of alveolar ventilation. The importance of understanding the shape of the capnogram as well as end-tidal carbon dioxide measurements is emphasized and its use in the early diagnosis of adverse events such as circuit disconnections, oesophageal intubation, defective breathing systems and hypoventilation is highlighted. Finally, the precautions required in the use and interpretation of capnography are presented with the caveat that although no instrument will replace the continuous presence of the attentive physician, end-tidal carbon dioxide monitoring can be effective in the early detection of anaesthesia-related intraoperative accidents.
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A patient is presented whose lumbar epidural catheter was found to lie in the paravertebral tissues during a right radical nephrectomy. The catheter had been placed with the patient awake and the procedure performed in a routine fashion without difficulty or indication of catheter malposition. Four ml of 2% CO2 lidocaine were initially injected as a test dose without any demonstrable effect. ⋯ Previous studies suggest that transforaminal escape of an epidural catheter occurs after 1-6% of insertions. It may occur without nerve root symptoms during catheter placement. The authors recommend that epidural catheters be introduced whilst the patients are awake and an effective block demonstrated before induction of general anaesthesia.
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Letter Randomized Controlled Trial Clinical Trial
Spinal catheter does not reduce post-dural puncture headache after caesarean section.
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The practice of obstetric anaesthesia can be highly rewarding. The clinician prepared with an understanding of maternal-fetal physiology (obstetric requirements), systemic narcotics, and regional anaesthesia can be highly effective at relieving pain and bringing about a successful delivery. While alternative techniques should always be considered, particularly those that stress childbirth education, continuous lumbar analgesia remains the most flexible and satisfactory approach. While there is new equipment (fine needles and smaller catheters) on the horizon, it remains to be demonstrated if they can match the success and safety record of present lumbar epidural practice.