Anaesthesia
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Breathing system filters are recommended for use during general anaesthesia. Manufacturers of gas sampling equipment recommend that gas is sampled from the 'machine side' of these filters, thereby avoiding contamination of the sampling line and waterlogging in the case of heat and moisture exchangers. ⋯ End-tidal carbon dioxide values were significantly lower at the machine side of the filter in both groups (p = 0.00001). The measurement error induced by the inclusion of the breathing system filter was significantly greater in the spontaneously breathing group (p = 0.0004).
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Clinical Trial Controlled Clinical Trial
Are coagulation studies on blood sampled from arterial lines valid?
Coagulation tests were performed on two venous blood samples and two blood samples from arterial lines taken from 79 patients on an intensive care unit. For the first arterial sample the discard volume was 4.5 ml and for the second arterial sample the discard volume was 16 ml. From each pair of venous samples a mean venous coagulation value was calculated. ⋯ No heparin was detectable in these arterial samples using a heparin assay (< 0.02 iu.ml-1). The differences between arterial and venous activated partial thromboplastin times were slightly but not significantly greater in subgroups of patients with moderately or severely deranged coagulation compared with a group with normal coagulation. We conclude that samples from arterial lines provide valid activated partial thromboplastin time results using a discard volume of either 4.5 ml or 16 ml.