Lithium dilution cardiac output measurement: a clinical assessment of central venous and peripheral venous indicator injection.
OBJECTIVE
The lithium indicator dilution technique has been shown to measure cardiac output (CO) accurately by using central venous injection of lithium chloride (Li-CCO). This study aimed to compare the measurement of CO by using peripheral venous administration of lithium chloride (Li-PCO) with Li-CCO.


METHODS
Prospective, observational human study.


METHODS
Surgical intensive care unit.


METHODS
Thirty-one patients were studied after major surgery. All patients had arterial, central, and peripheral venous catheters. A total of 24 patients had pulmonary artery catheters.


METHODS
Serial measurements of Li-CCO and Li-PCO were made during hemodynamically stable conditions. CO was also measured using thermodilution (TDCO) when a pulmonary artery catheter was present. Data were analyzed by linear regression, the generalized estimating equation, and the comparison method described by Bland and Altman.


RESULTS
There were 93 Li-CCOs, 93 Li-PCOs, and 216 TDCOs recorded. The ranges of COs were similar: Li-CCO, 2.36-11.52 L/min (mean, 5.22 L/min; n = 31); Li-PCO, 1.63-9.99 L/min (mean, 5.22 L/min; n = 31), and TDCO, 3.28-10.4 L/min (mean, 5.75 L/min; n = 24). There was good linear correlation between Li-CCO and Li-PCO (R2 =.845). The mean difference for Li-CCO-Li-PCO was very small and insignificant (p =.97), and the limits of agreement were acceptable (mean difference +/- sd, 0.0005 +/- 0.64 L/min). The mean difference for Li-CCO-Li-PCO was smaller if the peripheral injection site was proximal rather than distal to the wrist (p =.053). Li-PCO and Li-CCO values were lower than simultaneously obtained TDCO measurements (Li-PCO-TDCO, -0.538 +/- 0.95 L/min, p =.003; Li-CCO-TDCO, -0.526 +/- 0.67 L/min, p =.0001).


CONCLUSIONS
Li-PCO gives a measurement that agrees well with Li-CCO. Accuracy of Li-PCO is probably improved if a proximal arm vein is used. Li-PCO provides accurate measurements of CO without the risks of pulmonary artery or central venous catheterization.
Garcia-Rodriguez
Charles
C
Duke University Medical Center, Durham Veterans Affairs Medical Center, NC, USA.
Pittman
James
J
Cassell
Cynthia H
CH
Sum-Ping
John
J
El-Moalem
Habib
H
Young
Christopher
C
Mark
Jonathan B
JB
D002302:Cardiac Output; D002405:Catheterization, Central Venous; D002406:Catheterization, Peripheral; D002407:Catheterization, Swan-Ganz; D005121:Extremities / Q000098:blood supply; D006801:Humans; D007201:Indicator Dilution Techniques; D007275:Injections, Intravenous; D007601:Jugular Veins; D018021:Lithium Chloride / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013815:Thermodilution
D018021:Lithium Chloride