Computer-controlled closed-loop norepinephrine infusion system for automated control of mean arterial pressure in dogs under isoflurane-induced hypotension: a feasibility study.

Introduction: Intra-operative hypotension is a common complication of surgery under general anesthesia in dogs and humans. Computer-controlled closed-loop infusion systems of norepinephrine (NE) have been developed and clinically applied for automated optimization of arterial pressure (AP) and prevention of intra-operative hypotension in humans. This study aimed to develop a simple computer-controlled closed-loop infusion system of NE for the automated control of the mean arterial pressure (MAP) in dogs with isoflurane-induced hypotension and to validate the control of MAP by the developed system. Methods: NE was administered via the cephalic vein, whereas MAP was measured invasively by placing a catheter in the dorsal pedal artery. The proportional-integral-derivative (PID) controller in the negative feedback loop of the developed system titrated the infusion rate of NE to maintain the MAP at the target value of 60 mmHg. The titration was updated every 2 s. The performance of the developed system was evaluated in six laboratory Beagle dogs under general anesthesia with isoflurane. Results: In the six dogs, when the concentration [median (interquartile range)] of inhaled isoflurane was increased from 1.5 (1.5-1.5)% to 4 (4-4)% without activating the system, the MAP was lowered from 95 (91-99) to 41 (37-42) mmHg. In contrast, when the concentration was increased from 1.5 (1.0-1.5)% to 4 (4-4.8)% for a 30-min period and the system was simultaneously activated, the MAP was temporarily lowered from 92 (89-95) to 47 (43-49) mmHg but recovered to 58 (57-58) mmHg owing to the system-controlled infusion of NE. If the acceptable target range for MAP was defined as target MAP ±5 mmHg (55 ≤ MAP ≤65 mmHg), the percentage of time wherein the MAP was maintained within the acceptable range was 96 (89-100)% in the six dogs during the second half of the 30-min period (from 15 to 30 min after system activation). The median performance error, median absolute performance error, wobble, and divergence were - 2.9 (-4.7 to 1.9)%, 2.9 (2.0-4.7)%, 1.3 (0.8-1.8)%, and - 0.24 (-0.34 to -0.11)%·min-1, respectively. No adverse events were observed during the study period, and all dogs were extubated uneventfully. Conclusion: This system was able to titrate the NE infusion rates in an accurate and stable manner to maintain the MAP within the predetermined target range in dogs with isoflurane-induced hypotension. This system can be a potential tool in daily clinical practice for the care of companion dogs.

Plasticity of cardiovascular chemoreflexes after prolonged unilateral carotid body denervation: implications for its therapeutic use.

Unilateral carotid body denervation has been proposed as treatment for sympathetic-related human diseases such as systolic heart failure, hypertension, obstructive sleep apnea, and cardiometabolic diseases. The long-term therapeutic effects of carotid body removal will be maintained if the remnant "buffer nerves," that is, the contralateral carotid nerve and the aortic nerves that innervate second-order neurons at the solitary tract nuclei (NTS), do not modify their contributions to the cardiovascular chemoreflexes. Here, we studied the cardiovascular chemoreflexes 1 mo after unilateral carotid body denervation either by excision of the petrosal ganglion (petrosal ganglionectomy, which eliminates central carotid afferents) or exeresis of a segment of one carotid nerve (carotid neurectomy, which preserves central afferents). Cardiovascular chemoreflexes were induced by intravenous (iv) injections of sodium cyanide in pentobarbitone-anesthetized adult cats. After 1 mo of unilateral petrosal ganglionectomy, without significant changes in basal arterial pressure, the contribution of the contralateral carotid nerve to the chemoreflex increases in arterial pressure was enhanced without changes in the contribution provided by the aortic nerves. By contrast, after 1 mo of unilateral carotid neurectomy, the contribution of remnant buffer nerves to cardiovascular chemoreflexes remained unmodified. These results indicate that a carotid nerve interruption involving denervation of second-order chemosensory neurons at the NTS will trigger cardiovascular chemoreflex plasticity on the contralateral carotid pathway. Then, unilateral carotid body denervation as therapeutic tool should consider the maintenance of the integrity of carotid central chemoafferents to prevent plasticity on remnant buffer nerves.NEW & NOTEWORTHY Unilateral carotid body denervation has been proposed as treatment for sympathetic hyperactivity-related human disorders. Its therapeutic effectiveness for maintaining a persistent decrease in the sympathetic outflow activity will depend on the absence of compensatory chemoreflex plasticity in the remnant carotid and aortic afferents. Here, we suggest that the integrity of central afferents after carotid body denervation is essential to prevent the emergence of plastic functional changes on the contralateral "intact" carotid nerve.

Taurine Supplementation Inhibits Cardiac and Systemic Renin-Angiotensin System Overactivity After Cardiac Ischemia/Reperfusion in Adult Female Rats Perinatally Depleted of Taurine Followed by High Sugar Intake.

Perinatal taurine depletion and high sugar intake from weaning onward worsen cardiac damage and arterial pressure control after ischemia/reperfusion (IR) in adult male and female rats, which can be ameliorated by high taurine diets or inhibition of renin-angiotensin system. This study tests if taurine supplementation ameliorates cardiac damage and arterial pressure control in adult female rats via alterations of both cardiac and systemic renin-angiotensin system. Female Sprague-Dawley rats were fed normal rat chow and drank water alone (control, C) or water containing 3% beta-alanine (taurine depletion, TD) from conception to weaning, and female offspring were subjected to high sugar intake (normal rat chow and 5% glucose in water; CG and TDG) or the normal rat diet (CW and TDW). At 7 weeks of age, half of the rats in each group received 3% taurine in water (CW+T, CG+T, TDW+T, and TDG+T). One week later, rats were subjected to IR or Sham procedures followed by renal nerve recording, plasma and cardiac angiotensin II measurements. Cardiac angiotensin II levels significantly elevated in CG, TDW, and TDG. Further, plasma angiotensin II concentrations were significantly elevated only in the TDG, in consistent with a significant increase in renal nerve activity to juxtaglomerular cells, but not renal vessels and tubules. These abnormalities were ameliorated by short-term taurine supplementation. Thus, in adult female rats that are perinatally depleted of taurine followed by high sugar intake after weaning, taurine supplementation decreases the adverse effects of cardiac IR via inhibition of both cardiac and systemic renin-angiotensin system overactivity.

Anestesia epidural y control posoperatorio de la tensión arterial en pacientes con preeclampsia grave cesareadas / Epidural anesthesia and postoperative control of arterial pressure in patients with serious preeclampsia and who have undergone cesarean section

Introducción: La preeclampsia en Cuba tiene una incidencia de 10 a 12 y una mortalidad neonatal de 35 por ciento. Hay escasa evidencia acerca de si es adecuado el tratamiento estándar. Se acepta el uso de anestesia epidural en la preeclampsia grave porque, entre otros beneficios, estabiliza la presión arterial. Objetivo: Evaluar la eficacia de la anestesia epidural continua como coadyuvante en el control posoperatorio de la tensión arterial en pacientes con preeclampsia grave. Métodos: Se realizó un estudio experimental en el hospital Dr. Agostinho Neto en el periodo 2013-2016. Se incluyeron 180 gestantes entre 15 y 40 años con preeclampsia grave intervenidas por cesárea, ASA III; asignadas aleatoriamente a un grupo de estudio y otro de control. En ambos se procedió según la norma cubana de obstetricia para el tratamiento de la preeclampsia. El grupo control recibió analgesia posoperatoria según recomendaciones del protocolo hospitalario, mientras se empleó anestesia epidural continua con 12,5 mg/h de bupivacaína al 0,125 por ciento en el grupo de estudio. Se midió la tensión arterial sistólica, diastólica y media durante las ocho primeras horas posoperatorias: Resultados: La tensión arterial sistólica y diastólica se controló en 93 por ciento y 88 por ciento, respectivamente. En el grupo control, 47 por ciento necesitó tres drogas antihipertensivas, 6 por ciento evolucionó hacia la eclampsia. Se controlaron los síntomas en el 97 por ciento del grupo de estudio. La taquicardia fue el efecto secundario esperado más frecuente de la anestesia epidural. Conclusiones: La anestesia epidural con bupivacaína al 12,5 mg/h es eficaz como coadyuvante en el control de la tensión arterial en el posoperatorio de pacientes con preeclampsia grave(AU)

Introduction: Preeclampsia in Cuba has an incidence of 10 to 12 and a neonatal mortality of 35 percent. There is little evidence about the standard treatment. The use of epidural anesthesia in severe preeclampsia is accepted because, among other benefits, it stabilizes blood pressure. Objective: To evaluate the effectiveness of continuous epidural anesthesia as an adjuvant in the postoperative control of blood pressure in patients with severe preeclampsia. Method: An experimental study was performed at Dr. Agostinho Neto Hospital in the period 2013-2016. We included 180 pregnant women aged 15-40 and with severe preeclampsia undergoing cesarean section (ASA III), randomly assigned to a study group and a control group. In both cases, we used the Cuban obstetrical standard for treating preeclampsia. The control group received postoperative analgesia according to the recommendations of the hospital protocol, while continuous epidural anesthesia was used with 12.5 mg/h of bupivacaine 0.125 percent in the study group. Systolic, diastolic and mean arterial pressure were measured during the first eight postoperative hours. Results: Systolic and diastolic blood pressure was controlled in 93 percent and 88 percent, respectively. In the control group, 47 percent needed three antihypertensive drugs, while 6 percent evolved towards eclampsia. Symptoms were controlled in 97 percent of the study group. Tachycardia was the most common expected side effect of epidural anesthesia. Conclusions: Epidural anesthesia with 12.5 mg/h of bupivacaine is effective as an adjuvant in controlling postoperative blood pressure in patients with severe preeclampsia(AU)