Comparison of cardiac output measurements using transpulmonary thermodilution and conventional thermodilution techniques in anaesthetized dogs with fluid overload

Objective: To evaluate the agreement between cardiac output (CO) values obtained using a transpulmonary thermodilution technique (TPTDCO) and conventional thermodilution technique (TDCO) in anaesthetized dogs with fluid overload. Study design: Prospective experimental study. Animals: Six healthy Beagle dogs aged 7-8years. Methods: Dogs were anaesthetized with sevoflurane in oxygen, and catheters were inserted for TPTDCO and TDCO measurement. After instrumentation, baseline CO was measured using each technique at a central venous pressure (CVP) of 3-7mmHg. Dogs were subsequently administered lactated Ringer's solution and 6% hydroxyethyl starch to induce fluid overload. CO measurements were obtained using each technique at CVP values of 8-12mmHg, 13-17mmHg, 18-22mmHg and 23-27mmHg. Agreements between CO measurements obtained with the respective techniques were analysed using Dunnett's test, Pearson's correlation coefficient and Bland-Altman analysis. Results: Thirty pairs of CO values were obtained, ranging from 1.45Lminute(-1) to 4.69Lminute(-1) for TPTDCO and from 1.30Lminute(-1) to 4.61Lminute(-1) for TDCO. TPTDCO and TDCO values correlated strongly (r(2)=0.915, p<0.001). The bias and mean relative bias between TPTDCO and TDCO were 0.260.30Lminute(-1) (limits of agreement -0.29 to 0.81Lminute(-1)) and 9.7%, respectively. Conclusions and clinical relevance: TPTDCO and TDCO measurements obtained in anaesthetized dogs during fluid overload exhibited good agreement. Accordingly, transpulmonary thermodilution provides an accurate measurement of CO in dogs with fluid overload

Minimum Alveolar Concentration for Blunting Adrenergic Responses (MAC-BAR) of Sevoflurane in Dogs

It is well known that heart rate or arterial blood pressure may increase in response to surgical stimulation despite the absence of a purposeful movement. However, there is limited information regarding anesthetic requirement for blunting adrenergic response in dogs. This study was designed to compare the minimum alveolar concentrations of sevoflurane required to prevent autonomic response (MAC-BAR) and purposeful movement (MAC) in dogs. Sevoflurane MAC-BAR and MAC were determined in 5 beagle dogs by judging dogs\u27 response to a noxious electrical stimulus applied to the gingiva. The sevoflurane MAC-BAR was significantly higher than MAC (3.33 ± 0.48 vs 2.10 ± 0.28%, P=0.005). These results suggested that autonomic responses occurred at sevoflurane anesthetic concentrations at which purposeful movements were absent

Central venous blood gas and acid-base status in conscious dogs and cats

To determine the reference level of central venous oxygen saturation (ScvO_2) and clinical efficacy of central venous blood gas analysis, partial pressures of oxygen and carbon dioxide, pH, oxygen saturation, base excess (B.E.) and HCO_3 concentration were compared between simultaneously obtained central venous and arterial blood samples from conscious healthy 6 dogs and 5 cats. Comparisons between arteriovenous samples were performed by a paired t-test and Bland-Altman analysis. Between arteriovenous samples, B.E. showed good agreement, but there were significant differences in other parameters in the dogs, and no good agreement was detected in cats. The ScvO2 in dogs and cats were 82.3 ± 3.5 and 62.4 ± 13.5%, respectively. Central venous blood gas analysis is indispensable, especially in cats

Local cerebral blood flow assessment using transcranial Doppler ultrasonography in a dog with brain infarction in the right middle cerebral artery territory

A 12-year-old neutered male Chihuahua was diagnosed with acute brain infarction in the right middle cerebral artery (MCA) territory. Transcranial Doppler ultrasonography (TCD) was performed to assess the local cerebral blood flow at the time of diagnosis and after 4 and 31 hr. Initially, the right MCA retained blood flow but with a lower cerebral blood flow velocity (CBFV; 14.9 cm/sec) than the left MCA (27.9 cm/sec). The TCD vascular resistance variables were higher in the right than in the left MCA. An increase in the CBFV and a decrease in TCD vascular resistance variables were observed, consistent with improvements in neurological symptoms. TCD can be a non-invasive, and easy-to-use modality for bedside monitoring of cerebral edema and infarction