Cardiovascular monitoring in anesthetized neonatal foals often does not include CO determinations because of the invasiveness of most methods. Thermodilution and LiDCO are accepted methods for CO determination in foals. However, most studies1–4 in which investigators evaluated these techniques have been conducted in controlled research conditions1–4 because of the required invasive instrumentation of the patients, which includes catheterization of the right side of the heart and pulmonary artery for thermodilution and catheterization of a peripheral artery for LiDCO. Thus, use of thermodilution or LiDCO is typically not considered practical in a clinical setting.
Other less invasive methods, including transthoracic echocardiography and NICO, have been evaluated in anesthetized neonatal foals as alternatives to LiDCO.4 In that study, volumetric echocardiography by use of the Bullet method provided the best correlation to a wide range of CO values induced by various degrees of anesthetic depth in combination with inotropic or vasopressor support. Comparisons between the LiDCO and NICO methods included mean values for duplicate or triplicate LiDCO measurements, with a single NICO value obtained during the period required to complete the LiDCO determinations.
Because echocardiography may also be impractical in anesthetized patients undergoing surgery, for the study reported here, we collated data from 1 study4 with additional data obtained by the same laboratory group5 to establish the usefulness of the NICO method. The objective of the study reported here was to compare the NICO and LiDCO methods by use of single measurements obtained by use of both methods in anesthetized foals in which a full range of CO and arterial blood pressure values was manipulated by anesthetic depth and use of inotropic or vasopressor drugs, including dobutamine, norepinephrine, vasopressin, and phenylephrine.
Lithium dilution CO
Noninvasive CO measured by partial carbon dioxide rebreathing
End-tidal carbon dioxide
Systolic arterial pressure
Diastolic arterial pressure
Mean arterial pressure
Minimum alveolar concentration
DVM Stat, Corp for Advanced Applications, Newburg, Wis.
Anased, Akorn Inc, Decatur, Ill.
Valium, Abbott Laboratories, North Chicago, Ill.
VetaKet, Phoenix Scientific Inc, St Joseph, Mo.
IsoFlo, Abbott Laboratories, North Chicago, Ill.
S/5, Datex-Ohmeda Division, Helsinki, Finland.
DOT-34 NRC 300/375 M1014, Datex-Ohmeda Division, Helsinki, Finland.
Plasmalyte 148 with 5% dextrose, Baxter Healthcare Corp, Deerfield, Ill.
LiDCO cardiac computer CM 31-01, LIDCO Ltd, London, UK.
ABL system 605/600, Radiometer Medical A/S, Copenhagen, Denmark.
LiDCO sensor, LiDCO Ltd, London, UK.
Lithium chloride, LiDCO Ltd, London, UK.
NICO, Novametrix Medical Systems Inc, Wallingford, Conn.
Dobutamine, Bedford Laboratories, Bedford, Ohio.
Phenylephrine, Bedford Laboratories, Bedford, Ohio.
Levophed, Abbott Laboratories, North Chicago, Ill.
Vasopressin, American Regent Inc, Shirley, NY.
Medfusion model 2010i syringe pump, MedexInc, Duluth, Ga.
SigmaStat for Windows, version 2.03, SPSS Inc, Chicago, Ill.
ANOVA, SPSS for Windows, version 14.0, SPSS Inc, Chicago, Ill.
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