The 1L 404 oxygen alarm monitorWe were interested to read the article by A. R.

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Epidural administration of combinations of opioids and a local anaesthetic provides prompt and effective analgesia and is increasingly used in paediatric anaesthesia. However, respiratory depression by rostral spread of opioid in the CSF is by far the greatest concern after epidural morphine. An infant of three months of age underwent portoenterostomy (Kasai's operation) for extrahepatic biliary duct atresia. A median approach at the L3-L4 epidural interspace was used and a dose of 1 ml.kg-1 of 0.125% bupivacaine with adrenaline 1:400000 mixed with 50 micrograms.kg-1 morphine was injected using a 19 gauge Tuohy needle. Six h after epidural morphine, the infant developed respiratory depression with an increase in drowsiness, miosis and decreased respiratory rate. Low arterial saturation (SpO2) was detected by pulse oximetry and confirmed by blood gas analysis. An intravenous bolus of 5 micrograms.kg-1 naloxone followed by a 3-h infusion of 2 micrograms.kg-1.h-1 resulted in complete reversal of signs and symptoms of respiratory depression. Epidural opioids should be limited to paediatric patients admitted to specialized recovery units for the first postoperative day.

Oxygen content measurements determined optically by the Co-Oximeter correlated closely with those obtained using the manometric technique of Van Slyke. In those samples with a high content of carbon monoxide, the agreement between the two methods could be improved, by taking into consideration the concentration of carboxyhaemoglobin (COHb), since this plays no part in oxygen transport. The calculated values of the oxygen-binding capacity varied widely, with mean values less than the theoretical figure of 1.39 ml O2/g Hb. This difference was greater in those samples with a higher content of COHb. When the amount of haemoglobin combined with COHb was taken into consideration the mean corrected values approximated to the theoretical value of 1.39, thus supporting this as the mean value for the oxygen-binding capacity of haemoglobin, although the large individual variability persisted.

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