Assessment of microcirculatory perfusion in healthy anesthetized cats undergoing ovariohysterectomy using sidestream dark field microscopy

Abstract

Objective: To: (1) determine the feasibility of using sidestream dark field microscopy (SDM) to measure microcirculatory parameters in healthy, anesthetized cats and (2) determine if surgical tissue manipulation and anesthesia time alter these parameters during ovariohysterectomy.

Design: Prospective observational study.

Setting: University teaching hospital.

Animals: Eighteen healthy female cats.

Interventions: Sublingual mucosa microcirculatory videos were obtained under general anesthesia preoperatively, intraoperatively, and postoperatively using an SDM device in healthy cats presenting for ovariohysterectomy. At each video acquisition point, macrovascular parameters (heart rate, blood pressure, pulse oximetry, end-tidal CO2) were recorded. Vascular analysis software was used to calculate standard microcirculatory parameters. Multivariate analysis was performed to compare microvascular and macrovascular parameters, as well as correlation with the effect of surgical manipulation and time under anesthesia.

Measurements and main results: Twelve of 18 cats were included in final video analysis; 6 were removed for poor video quality. Values for total vessel density (TVD, 47.7 ± 8.39 mm/mm(2)), proportion of perfused vessels (PPV, 88.2 ± 5.95%), perfused vessel density (PVD, 43.0 ± 9.00 mm/mm(2)), microcirculatory flow index (MFI, 2.33 ± 0.33) were determined preoperatively. There were no significant changes in TVD, PPV, and PVD across intervention points. The MFI increased significantly from preoperative to intra- and postoperative data collection points. No correlation between microcirculatory parameters and length of anesthesia or macrocirculatory values was found.

Conclusions and clinical relevance: This study demonstrated that SDM can be utilized to obtain sublingual microvascular parameters in healthy, anesthetized cats. Limitations include difficulty in obtaining high quality images, presumed need for general anesthesia, and need for off-line video analysis. This technology has potential as a tool in experimental and clinical monitoring of microcirculatory changes in felines.

Keywords: cardiovascular physiology; critical care; monitoring; sepsis.