Since it is impossible to sample the artery directly vascularizing the tumour, the gold standard is serial arterial sampling of a superficial artery (e.g. the radial artery) after which the activity concentration of the plasma derived by centrifugation can be determined [ 105].
Whole blood arterial samples for assay of remifentanil concentrations were obtained before and 5 min after each adjustment of the infusion rate.
Although we informed staff in the emergency department staff of the importance of arterial samples for this trial, compliance was low and only 11% of arterial samples were drawn within 30 minutes of arrival.
The use of capillary samples for blood glucose instead of arterial samples and use of the point-of-care glucose meter could be considered a further limitation.
In CHR ICUs, lactate is nearly always determined from venous and arterial samples using point-of-care analysers in each of the ICUs (Radiometer ABL-725, Radiometer Copenhagen, Copenhagen, Denmark).
Previous work by the group [ 2] demonstrated that injection of a small bolus of glucose (5 g) followed by serial measurements of glucose concentration from arterial samples allowed calculation of the initial distribution volume of glucose (IDVG).
