Key result
Norepinephrine treats isoflurane-induced hypotension, increasing cardiac index ~67% at high doses.
Why the study?
The cardiovascular effects of increasing doses of norepinephrine in healthy, isoflurane-anesthetized cats had not been determined.
Does norepinephrine improve cardiovascular variables in isoflurane-anesthetized cats with hypotension?
Does norepinephrine improve cardiovascular variables in isoflurane-anesthetized cats with hypotension?
Norepinephrine effectively treats isoflurane-induced hypotension in healthy cats in a dose-dependent manner, though higher doses may cause arrhythmias.
Answers are grounded in this paper and cite their sources.
May support norepinephrine for feline isoflurane hypotension; leaves open clinical translation pending trials.
Objective To determine the cardiovascular effects of increasing doses of norepinephrine (NE) in healthy, isoflurane-anesthetized cats. Study design Prospective experimental study. Animals Eight healthy, 1 year old, male neutered, domestic shorthair cats, with body masses of 4.7–6.8 kg. Methods Cats were premedicated intramuscularly with butorphanol, midazolam and alfaxalone. Anesthesia was induced with intravenous alfaxalone and maintained with an end-tidal isoflurane concentration of 1.9–2.1% to cause hypotension, under volume-controlled ventilation. Cats were given NE at three doses in the following order: low; 0.1 μg kg -1 minute -1 (LNE), intermediate; 0.5 μg kg -1 minute -1 (INE), and high; 1.0 μg kg -1 minute -1 (HNE). Infusions lasted 15 minutes, followed by an interval of 10 minutes, to reach steady state at each phase. Cardiopulmonary variables recorded before (baseline) and during the NE dose, included heart rate (HR), cardiac index (CI), and direct systolic, mean and diastolic arterial blood pressures (SAP, MAP, DAP). Effects of each dose and between doses on cardiovascular variables were compared with a one-way ANOVA and a two-way ANOVA, for repeated measures, respectively, followed by multiple pairwise comparisons with a Tukey’s test ( p < 0.05 considered significant). Results From baseline, all three doses of NE caused significant increases in SAP, MAP, DAP and end-tidal CO 2 , at 7 and 15 minutes of infusion, and HNE caused a significant increase in CI at 15 minutes (61 ± 13 versus 102 ± 18 mL kg -1 minute -1 , respectively; p = 0.002). HR increased significantly at 15 minutes with INE and throughout the infusion with HNE [123 ± 18 at baseline, 149 ± 10 at 7 minutes ( p = 0.001) and 155 ± 10 beats minute -1 ( p = 0.002)]. INE and HNE were associated with arrhythmias. Conclusion and clinical relevance Norepinephrine is effective in a dose-dependent fashion at treating isoflurane-induced hypotension in healthy cats.
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Skelding et al. (2026) studied isoflurane-induced hypotension (n=8). Norepinephrine vs. baseline was evaluated on cardiovascular variables including systolic, mean, and diastolic arterial blood pressures, and cardiac index (p=0.002). Norepinephrine effectively treated isoflurane-induced hypotension in a dose-dependent fashion, significantly increasing arterial blood pressures and cardiac index (102 vs 61 mL/kg/min at high dose; P=0.002).
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