Cardiac output measured by lithium dilution, thermodilution, and transesophageal Doppler echocardiography in anesthetized horses

Abstract

These results indicate that lithium dilution is a suitable method for measuring cardiac output in horses. As well as being accurate, it avoids the need for pulmonary artery catheterization and is quick and safe to use. Monitoring cardiac output during anesthesia in horses may help reduce the high anesthetic mortality in this species.

Pharmacokinetics and toxic effects of lithium chloride after intravenous administration in conscious horses

“…1,5 Mean cumulative dose of lithium chloride in horses in our study was 0.13 ± 0.01 mmol/kg (expressed on a body-weight basis). Lithium disposition is normally addressed, at least in humans, in terms of steady-state kinetics because of the long-term nature of the therapeutic exposure.…”

“…A dose of 2.25 mmol provided an adequate signal for a single cardiac output determination in anesthetized horses weighing 480 to 620 kg. 5 Because the accuracy of the lithium detector is influenced by the accumulation of background plasma lithium concentrations, and an upper limit for background concentrations of 0.2 mmol/L has been recommended, g the maximum number of replicated determinations during a reasonable period of drug (ie, treatment) administration (2 to 4 hours) is estimated to be ≤ 10 (eg, total dose of lithium chloride, 22.5 mmol).…”

“…5 On the basis of these studies, it appears that cardiac output measured via lithium chloride dilution is a safe, simple, and accurate technique that yields results at least as accurate as those for bolus thermodilution. Historically, cardiac output measurements in horses have been performed by use of dye dilution or thermodilution.…”

“…The method offers a number of possible advantages for estimation of cardiac output in a clinical setting. 5 Lithium chloride has been used extensively in human medicine for prophylactic and therapeutic treatment of unipolar and bipolar manic-depressive disorders. 10,11 Its use as a salt substitute for patients requiring low-sodium intake resulted in several unfortunate clinical episodes in the 1940s and led to its removal from the market.…”

Haemodynamic monitoring in acute heart failure

“…Although newer and more representative indices of preload have shifted their focus from pressure to volume, the former is still the basis for the most widely used preload measurements in clinical practice [10]. Most of the new devices that measure volumes are also able to calculate cardiac output, which is important for the second of the above haemodynamic goals [29][30][31][32][33].…”