DOI: 10.25338/b8q937
title: Trazodone and dexmedetomidine cause fentanyl to decrease the isoflurane minimum alveolar concentration in cats

description: Objective: To screen modulators of biogenic amine (BA)
 neurotransmission for the ability to cause fentanyl to decrease isoflurane
 minimum alveolar concentration (MAC) in cats, and to test whether fentanyl
 plus a combination of modulators decreases isoflurane MAC more than
 fentanyl alone. Study design: Prospective, crossover Animals: 6 male
 domestic shorthair cats Methods: Each cat was anesthetized 3 times with a
 1-week washout period. First, anesthesia was induced and maintained with
 isoflurane, and MAC was measured in duplicate using a tail clamp stimulus
 and standard bracketing technique. A 21 ng mL-1 fentanyl target-controlled
 infusion (TCI) was next administered, and MAC was re-measured. Second,
 each cat was administered 1 BA modulator drug (buspirone, haloperidol,
 dexmedetomidine, pregabalin, ramelteon, or trazodone), and isoflurane MAC
 was measured before and after fentanyl administration. Third, isoflurane
 MAC was measured in cats administered 50mg oral trazodone plus a 1.05 ng
 mL-1 intravenous dexmedetomidine TCI before and after fentanyl
 administration. Isoflurane MAC-sparing by fentanyl alone,
 trazodone-dexmedetomidine, and trazodone-dexmedetomidine-fentanyl was
 evaluated using paired t-tests with p &lt; 0.05 denoting significant
 effects. Results: MAC of isoflurane was 1.87% ± 0.09 and was not
 significantly affected by fentanyl administration (p = 0.09). In the BA
 screen, cats administered trazodone or dexmedetomidine exhibited 26% and
 22% fentanyl MAC-sparing, respectively. Trazodone plus dexmedetomidine
 co-administration reduced isoflurane MAC to 1.50% ± 0.14 (p = 0.0004), and
 fentanyl further decreased MAC to 0.95% ± 0.16 (p = 0.000004). Conclusions
 and clinical relevance: Fentanyl alone does not affect isoflurane MAC in
 cats, but co-administration of trazodone and dexmedetomidine causes
 fentanyl to significantly decrease isoflurane requirement.
description: Minimum alveolar concentration (MAC) was measured twice (in
 duplicate) for each cat. Data were collected prior to nociceptive tail
 clamp stimulation for MAC testing. Physiologic responses measured at
 bracketing (move and no-move) anesthetic concentrations were averaged.
 Responses for each animal represent the mean of duplicate physiologic
 response pairs.
description: # Trazodone and dexmedetomidine cause fentanyl to decrease the isoflurane
 minimum alveolar concentration in cats ## Description of the data and file
 structure Data are for 6 cats. "Iso" are values measured during
 isoflurane anesthesia in unmedicated cats. "Iso_F" are values
 measured during isoflurane anesthesia during a 21ng/mL fentanyl
 target-controlled infusion. "Iso_TD" are values measured during
 isoflurane anesthesia in cats that were premedicated with 50mg/kg
 trazodone and concurrently receiving a 1.05ng/mL dexmedetomidine
 target-controlled infusion. "Iso_TD_F" are values measured
 during isoflurane anesthesia in cats that were premedicated with 50mg/kg
 trazodone and concurrently receiving a 1.05ng/mL dexmedetomidine
 target-controlled infusion and a 21ng/mL fentanyl target-controlled
 infusion. Data include MAC (isoflurane minimum alveolar concentrations, in
 %atm), HR (in beats/min), SpO2 (peripheral capillary oxygen saturation, in
 %), MAP (mean arterial blood pressure, in mmHg), Norepi infusion
 (administration rate of norepinephrine used to maintain normotension, in
 mcg/kg/min), PCO2 (end-tidal partial pressure of carbon dioxide, in mmHg),
 SV (the fraction of time that the cats were spontaneously ventilating
 during the ventilator expiratory pause), Temp (body temperature, in
 degrees Celsius) ## Sharing/Access information Not applicable. ##
 Code/Software Not applicable.