A modification of the blood sampling technique in critical care to reduce blood wastage

Introduction

Diagnostic blood sampling is an indispensable and effective tool for assessing critically ill patients. However, the amount of blood drawn daily can be substantial and deleterious to patient care [1]. A recent survey [2] on arterial blood sampling practices in the ICU in England and Wales concluded that blood conservation is underused. There is commercially available equipment to assist in this by ensuring that the amount of blood disposed during sampling could be kept to a minimum. This equipment significantly increases the cost of most critically ill patients. We therefore designed, taught and assessed a sampling technique that could be performed without modification of the standard transducer connection, in which any blood returned was always contained within the closed sterile environment of the transducer tubing.

Method

Blood was initially drawn form the distal three-way tap through the 120 cm extension tubing. As soon as blood reached this three-way tap, a total of 2.8 ml had been withdrawn and a further 0.2 ml was withdrawn from the proximal tap, followed by the sample in the usual way. The blood still within the tubing could be flushed back to the patient. In this way we were able to reduce blood wastage from 3 ml to 0.2 ml per sample. We trained all staff for a 2 month period and then proceeded to audit the use of this technique, allowing us to estimate the amount of blood wastage that was saved over a 2 month period.

Results

During the study period, 949 separate sampling episodes occurred in 63 patients. All staff confirmed that they had followed the new technique during this period, and daily observation by the authors failed to identify any episode when this was not the case. During the study period, the technique reduced blood wastage during sampling by 2657 ml.

Conclusions

This technique is a simple cost-effective approach that minimises blood wastage which could be successfully taught and is feasible for everyday use in the critical care environment.