Blood gas analysis: a study of blood loss in intensive care

This paper describes a quantitative study conducted on an intensive care unit in the north of England. It involved the collection of data from the existing records of 65 patients consecutively sampled from a predetermined date provided that they stayed more than 24 hours and had an arterial line in situ. As patient records were used, ethical approval was not necessary. The objectives of the study were to quantify the mean number of blood gas samples taken per patient and estimate the mean blood loss resulting from this, including discard volume. Limitations include reliance on records and lack of an economic evaluation. The results show that blood loss in this study was greater than that reported elsewhere. Patients who were ventilated for 24 hours or more had a statistically significant greater blood loss when compared to those who were not (P < 0.001). A subgroup of patients undergoing renal replacement therapy had the greatest blood loss (mean 55.18 ml per day). This loss was statistically significant when compared to patients not in acute renal failure (P=0.007). When patients undergoing multiple therapies normally associated with increased sampling were compared to patients not receiving such therapies, there was no statistically significant difference in blood loss. The need to change current nursing practice to reduce iatrogenic anaemia is emphasized.