Lithium dilution cardiac output (LiDCO) measurement using peripheral venous injection of lithium chloride

Background

We have previously described a simple indicator dilution method of measuring cardiac output in which lithium chloride is injected via a central venous catheter and its plasma concentration-time curve measured in arterial blood using a lithium selective electrode [1]. This technique has the advantage of requiring only central venous and arterial cannulation and therefore avoids pulmonary artery catheterisation.

There are many patients who have arterial cannulae and peripheral, rather than central, venous access in whom cardiac output measurements would greatly assist management.

We have therefore explored the feasibility of measuring cardiac output using a peripheral rather than central venous injection of lithium chloride.

Methods

Ten stable patients with peripheral (antecubital vein), central venous and arterial cannulae on a General Intensive Care Unit were studied. For each patient, 10 consecutive LiDCO measurements of cardiac output were made at 5-min intervals. The injections of lithium chloride were given alternately via the peripheral and central venous cannulae and the cardiac outputs calculated from the arterial plasma concentration-time curves. For each patient the average of the five LiDCO measurements obtained using peripheral venous injection was compared with the average of the five LiDCO measurements obtained using the central venous route.

Results

There was good agreement between the two methods (r ² = 0.98) and the results are summarised in the Table.

Conclusion

This study shows that LiDCO can be measured using peripheral or central venous injections of lithium chloride. Safe, quick and reliable cardiac output measurements can therefore be obtained in patients with arterial and antecubital venous access.

Table 1