Xenon/Remifentanil Anesthesia Protects Against Adverse Effects of Losartan on Hemodynamic Challenges Induced by Anesthesia and Acute Blood Loss

Abstract

The authors aimed to test the hypothesis that xenon anesthesia limits adverse hypotensive effects of losartan during acute hemorrhage. In six conscious unsedated Beagle dogs, the systemic and pulmonary circulation were monitored invasively, and two subsequent 60-min hypotensive challenges were performed by (a) induction (propofol) and maintenance of anesthesia with isoflurane/remifentanil or xenon/remifentanil and by (b) subsequent hemorrhage (20 mL kg⁻¹ within 5 min) from a central vein. The same amount of blood was retransfused 1 h after hemorrhage. Experiments were performed with or without acute angiotensin II receptor subtype 1 blockade by i.v. losartan (100 μg·kg⁻¹·min⁻¹) starting 45 min before induction of anesthesia. Four experiments were performed in each individual dog. Xenon/remifentanil anesthesia provided higher baseline mean arterial blood pressure (85 ± 6 mmHg) than isoflurane/remifentanil anesthesia (67 ± 3 mmHg). In losartan-treated animals, isoflurane/remifentanil caused significant hypotension (42 ± 4 mmHg for isoflurane/remifentanil vs. 71 ± 6 mmHg for xenon/remifentanil). Independent of losartan, hemorrhage did not induce any further reduction of mean arterial blood pressure or cardiac output in either group. Spontaneous hemodynamic recovery was observed in all groups before retransfusion was started. Losartan did not alter the adrenaline, noradrenaline, and vasopressin response to acute hemorrhage. Losartan potentiates hypotension induced by isoflurane/remifentanil anesthesia but does not affect the hemodynamic stability during xenon/remifentanil anesthesia. Losartan does not deteriorate the hemodynamic adaptation to hemorrhage of 20 mL kg⁻¹ during xenon/remifentanil and isoflurane/remifentanil anesthesia. Therefore, xenon/remifentanil anesthesia protects against circulatory side effects of losartan pretreatment and thus may afford safer therapeutic use of losartan during acute hemorrhage.

Combining xenon and mild therapeutic hypothermia preserves neurological function after prolonged cardiac arrest in pigs*

“…In hemodynamically unstable patients, furthermore, Xe preserves arterial pressures and heart-rate variability (8,44,45). CA often occurs as a manifestation of myocardial infarction, and patients successfully resuscitated from OHCA exhibit left-ventricular dysfunction as a result of myocardial stunning (46,47).…”

Xenon

“…Compared with nitrous oxide, xenon had no effect on arterial blood pressure and myocardial contractility, and caused a minor decrease in heart rate. 50 Xenon does not seem to have the same vasodilatory effects as most other commonly used anesthetics. 8,20,37 The first randomized controlled multicenter study compared xenon with isoflurane-nitrous oxide anesthesia.…”

Evaluation of hemodynamic effects of xenon in dogs undergoing hemorrhagic shock

“…However, few studies have evaluated the impact of xenon on hemodynamics, oxygen transport and tissue perfusion during circulatory shock (12,13). It is well known that most inhalational anesthetics used in clinical practice may hinder hemodynamic responses to shock, either by directly interfering with cardiac function or the vascular contractile response or by indirectly decreasing sympathetic activity.…”