Evaluation of oesophageal Doppler-derived variables and plethysmographic variability index to predict fluid responsiveness in mechanically ventilated healthy dogs

Abstract

Evaluate the plethysmography variability index (PVI) and oesophageal Doppler (OD)-derived dynamic variables [stroke distance variation (StDV) and aortic flow peak velocity variation (PVV)] as predictors of fluid responsiveness. Dogs received dexmedetomidine (3 mg kg-1) and methadone (0.3 mg kg-1), intramuscularly. Anaesthesia was induced with propofol and maintained with isoflurane. Volume-controlled ventilation was instituted with tidal volume 10 mL kg-1, inspiratory-to-expiratory ratio 1:2. Heart rate (HR) and mean arterial pressure (MAP) were monitored. An OD probe was inserted to measure stroke distance (StD). Once surgery finished, PVV, StDV and PVI were recorded before (T0) and after (T1) the administration of 3 mL kg-1 bolus of hydroxyethyl starch 6% over 5 minutes. Dogs were classified as fluid-responders (R; StD increased 15%) or non-fluid-responders (NR). Receiver operating characteristic (ROC) curves were plotted for PVV, StDV and PVI.