A Comparison of Dobutamine, Norepinephrine, Vasopressin, and Hetastarch for the Treatment of Isoflurane-Induced Hypotension in Healthy, Normovolemic Dogs

Abstract

Isoflurane is a commonly used inhalation anesthetic in species undergoing veterinary care that induces hypotension, impacting organ perfusion, making it imperative to minimize its occurrence or identify effective strategies for treating it. This study evaluated and compared the hemodynamic effects of DOB, NEP, VAS, and HES in twelve isoflurane-anesthetized Beagle dogs. The order of the first three treatments was randomized. HES was administered last. Data were collected before treatments (baseline) and after 10 min of a sustained MAP of <45 mmHg induced by a high end-tidal isoflurane concentration (T0). Once treatment was initiated and the target MAP was achieved (65 to 80 mmHg) or the maximum dose reached, data were collected after 15 min of stabilization (T1) and 15 min after (T2). A 15 min washout period with a MAP of ≥65 mmHg was allowed between treatments. The intravenous dosage regimens started and were increased by 50% every five minutes until the target MAP or maximum dose was reached. The dosages were as follows: DOB, 5–15 μg/kg/min; NEP, 0.1–2 μg/kg/min; VAS, 0.5–5 mU/kg/min; and HET, 6% 1–20 mL/kg/min. DOB improved CO, DO2, and VO2, but reduced SVR. VAS elevated SVR, but decreased CO, DO2, and VO2. HES minimally changed BP and mildly augmented CO, DO2, and VO2. These treatments failed to reach the target MAP. NEP increased the arterial BP, CO, MPAP, and PAWP, but reduced HR. Norepinephrine infusion at 0.44 ± 0.19 μg/kg/min was the most efficient therapy for correcting isoflurane-induced hypotension.

What is the best treatment for hypotension in healthy dogs during anaesthesia maintained with isoflurane?

“…Furthermore, some studies documented a decline in SVR in response to high volume crystalloid fluid therapy further exacerbating anaesthetic induced reductions in SVR and hypotension. 16,24,27 Large volumes of fluids may also dilute circulating red blood cells thus inhibiting increased oxygen delivery (DO 2 ) despite increased CO. 16,21,24 The majority of reviewed studies evaluated pharmacological interventions aimed at increasing blood pressure (Table 5). Dopamine infusions consistently increased blood pressure in all studies where it was used (Table 4 -Studies 2, 3, 4, 5, 9 and 11).…”

“…34 Unlike the some of the studies evaluating dopamine neither noradrenaline study reported UoP or other renal parameters preventing any comparison of the renal effects of these two drugs. 13,27 Currently there are no studies directly comparing noradrenaline and dopamine for treating hypotension in dogs. Consequently, it is not possible to conclude if the two treatments are equivalent in terms of renal effects, efficacy for correcting hypotension or relevant outcomes such as survival or duration of hospitalisation.…”

Impact of a Dexmedetomidine Intravenous Infusion in Septic Dogs: Preliminary Study

“…The length of hospitalization between the two groups was not statistically different: 7 (4-10) days in the DEX group vs. 7 (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) days in the NaCl group (p = 0.14).…”

“…Considering a mean dosage of norepinephrine of 0.44 ± 0.19 mcg/kg/h [ 13 ] with an α error of 0.05 and β error of 0.2, in order to assess a decrease of 40% in the mean dosage of norepinephrine for the DEX group, a minimum requirement of 8 dogs in each group was calculated.…”

Manejo Anestésico de Paciente con Síndrome Respiratorio Braquiocefálico Sometido a Cirugía Correctiva: Estudio de Caso

“…El sevoflurano e isoflurano son anestésicos inhalatorios ampliamente utilizados en medicina veterinaria para la anestesia general Henao-Guerrero et al (2023). El isoflurano, en particular, exhibe una capacidad hipotensora dosis-dependiente al provocar la dilatación de los vasos periféricos y la depresión del miocardio (Kojima et al, 2021).…”