Use of plethysmographic variability index and perfusion index to evaluate changes in arterial blood pressure in anesthetized tigers (Panthera tigris)

Abstract

OBJECTIVE To investigate use of the plethysmographic variability index (PVI) and perfusion index (PI) for evaluating changes in arterial blood pressure in anesthetized tigers (Panthera tigris). ANIMALS 8 adult tigers. PROCEDURES Each tiger was anesthetized once with a combination of ketamine, midazolam, medetomidine, and isoflurane. Anesthetic monitoring included assessment of PI, PVI, direct blood pressure measurements, anesthetic gas concentrations, esophageal temperature, and results of capnography and ECG. Mean arterial blood pressure (MAP) was maintained for at least 20 minutes at each of the following blood pressure conditions: hypotensive (MAP = 50 ± 5 mm Hg), normotensive (MAP = 70 ± 5 mm Hg), and hypertensive (MAP = 90 ± 5 mm Hg). Arterial blood gas analysis was performed at the beginning of anesthesia and at each blood pressure condition. RESULTS Mean ± SD PI values were 1.82 ± 2.38%, 1.17 ± 0.77%, and 1.71 ± 1.51% and mean PVI values were 16.00 ± 5.07%, 10.44 ± 3.55%, and 8.17 ± 3.49% for hypotensive, normotensive, and hypertensive conditions, respectively. The PI values did not differ significantly among blood pressure conditions. The PVI value for the hypotensive condition differed significantly from values for the normotensive and hypertensive conditions. The PVI values were significantly correlated with MAP (r = -0.657). The OR of hypotension to nonhypotension for PVI values ≥ 18% was 43.6. CONCLUSIONS AND CLINICAL RELEVANCE PVI was a clinically applicable variable determined by use of noninvasive methods in anesthetized tigers. Values of PVI ≥ 18% may indicate hypotension.

Anesthesie van vijf amurtijgers (Panthera tigris altaica) met een combinatie van medetomidine en ketamine

“…In tigers, the most often described combination is ketamine associated with an alpha 2 agonist such as xylazine (Allwin et al, 2018;Goodrich et al, 2001;Larsson et al, 2008;Sontakke et al, 2009), medetomidine (Forsyth et al, 1999;Miller et al, 2003;Zeiler et al, 2013) or dexmedetomidine (Cesare et al, 2018;Clark-Price et al, 2015). Combinations of ketamine with midazolam and an alpha 2 agonist have also been reported (Clark-Price et al, 2015;Curro et al, 2004;Reilly et al, 2014;Smith et al, 2018). Tiletamine, another dissociative agent, in combination with zolazepam, has also been described in tigers, as sole agents (Seidensticker et al, 1974) or in combination with medetomidine (Lewis et al, 2014), detomidine (Laricchiuta et al, 2014) or xylazine (Mercado et al, 2020).…”

Dexmedetomidine and ketamine simultaneous administration in tigers (Panthera tigris): pharmacokinetics and clinical effects

“…Different drug combinations are used to immobilise captive tigers ( Panthera tigris ), all of them include α2 agonists, which nowadays are considered essential components of anaesthetic protocols 2–6. In this species, α2 agonists contribute to producing dose‐dependent, reliable immobilisation 5.…”