Sevoflurane preconditions stunned myocardium in septic but not healthy isolated rat hearts

Nitrite administration improves sepsis-induced myocardial and mitochondrial dysfunction by modulating stress signal responses

PURPOSE

A specific therapeutic strategy in sepsis-induced myocardial dysfunction remains to be determined. Nitrite may have cardioprotective effects against sepsis-induced myocardial dysfunction. This study investigated the cardioprotective effects of nitrite on myocardial function, mitochondrial bioenergetics, and its underlying molecular mechanisms in severe septic rats.

METHODS

Sepsis was induced in male Wistar rats by cecal ligation and puncture (CLP). After CLP, we administered normal saline (NS group) or nitrite (nitrite group) subcutaneously. We administered nitrite at different doses (0.1-10 mg/kg) to ascertain the most effective dose and examined cardiac function in an isolated heart experiment 8 h after CLP. We investigated mitochondrial bioenergetics and molecular mechanisms underlying the administration of nitrite in vitro.

RESULTS

In isolated heart experiments, the left ventricular developed pressure (96 ± 5 mmHg) at a moderate nitrite dose (1.0 mg/kg) was significantly higher than that in the NS group (75 ± 4 mmHg, P < 0.05). Mitochondrial oxidative phosphorylation in the nitrite group was significantly higher than that in the NS group (P < 0.01). Immunoblotting revealed that nitrite significantly increased the phosphorylation of Akt (P < 0.05) and reduced the nuclear translocation of NF-κB (P < 0.05) compared with the NS group. Nitrite was also shown to improve the rate of survival in severe septic rats (P < 0.001).

CONCLUSIONS

Our results showed that a moderate nitrite dose improved septic myocardial dysfunction at organ, cellular, and molecular levels via modulation of stress signal responses, which resulted in an improvement in survival.

Sepsis-induced cardiac dysfunction and β-adrenergic blockade therapy for sepsis

Despite recent advances in medical care, mortality due to sepsis, defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, remains high. Fluid resuscitation and vasopressors are the first-line treatment for sepsis in order to optimize hemodynamic instability caused by vasodilation and increased vascular permeability. However, these therapies, aimed at maintaining blood pressure and blood flow to vital organs, could have deleterious cardiac effects, as cardiomyocyte damage occurs in the early stages of sepsis. Recent experimental and clinical studies have demonstrated that a number of factors contribute to sepsis-induced cardiac dysfunction and the degree of cardiac dysfunction is one of the major prognostic factors of sepsis. Therefore, strategies to prevent further cardiomyocyte damage could be of crucial importance in improving the outcome of sepsis. Among many factors causing sepsis-induced cardiac dysfunction, sympathetic nerve overstimulation, due to endogenous elevated catecholamine levels and exogenous catecholamine administration, is thought to play a major role. β-adrenergic blockade therapy is widely used for ischemic heart disease and chronic heart failure and in the prevention of cardiovascular events in high-risk perioperative patients undergoing major surgery. It has also been shown to restore cardiac function in experimental septic animal models. In a single-center randomized controlled trial, esmolol infusion in patients with septic shock with persistent tachycardia reduced the 28-day mortality. Furthermore, it is likely that β-adrenergic blockade therapy may result in further beneficial effects in patients with sepsis, such as the reduction of inflammatory cytokine production, suppression of hypermetabolic status, maintenance of glucose homeostasis, and improvement of coagulation disorders. Recent accumulating evidence suggests that β-adrenergic blockade could be an attractive therapy to improve the prognosis of sepsis. We await a large multicenter randomized clinical trial to confirm the beneficial effects of β-adrenergic blockade therapy in sepsis, of which mortality is still high.

Volatile anaesthetics and cardiac protection in abdominal surgery

BACKGROUND

Clinical studies have shown that sevoflurane is cardio-protective in cardiac surgery patients, but this effect is doubtful in general surgery patients. This study has researched the influence of sevoflurane on the perioperative cardiac function and the incidence of cardiac ischaemic events in abdominal surgical patients.

METHODS

Out of 80 patients scheduled for elective colorectal surgery, 42 received balanced sevoflurane-fentanyl anaesthesia, while 38 received intravenous midazolam-fentanyl anaesthesia. The cardiac index (CI) and cardiac function index (CFI) were measured by the PiCCO device, and Troponin I levels were measured at the beginning of surgery, as well as 4, 12 and 24 h afterwards. BNP was measured at the beginning of surgery, and 24 h afterwards. The data analysis was conducted using the Mann-Whitney nonparametric test, with statistical significance set at p < 0.05.

RESULTS

There was no statistical difference in perioperative Troponin I, BNP, CI and CFI values between the SEVO and TIVA groups throughout the perioperative period.

CONCLUSIONS

Sevoflurane had no effect on the cardiac biomarkers Troponin I and BNP, and on the PiCCO parameters of cardiac function in abdominal surgical patients. Further research on the preconditioning effect of volatile anaesthetics in general surgical population should be concentrated on the population of patients with a high perioperative cardiac risk.

Infusion of the β-adrenergic blocker esmolol attenuates myocardial dysfunction in septic rats*

OBJECTIVE

Since beta-blocker therapy is known to be effective in patients with an injured heart, such as infarction, we designed the present study to examine the protective effects of infusion of the beta1-selective blocker esmolol on myocardial function in peritonitis-induced septic rats using an isolated working heart preparation.

DESIGN

Randomized animal study.

SETTING

University research laboratory.

SUBJECTS

Thirty-one rats treated with cecal ligation and perforation to evoke peritonitis.

INTERVENTIONS

After cecal ligation and perforation, rats were randomly allocated to the control group (normal saline 2 mL/hr, n = 11), low-dose esmolol group (10 mg/kg/hr, n = 10), or high-dose esmolol group (20 mg/kg/hr, n = 10). After obtaining blood samples for measurement of arterial lactate and tumor necrosis factor-alpha at 24 hrs, we assessed cardiac output, myocardial oxygen consumption, and cardiac efficiency (cardiac output x peak systolic pressure/myocardial oxygen consumption) at various preloads in an isolated perfused heart preparation.

MEASUREMENTS AND MAIN RESULTS

Esmolol infusion did not cause an elevation of arterial lactate levels but reduced tumor necrosis factor-alpha concentrations vs. the control group (p < .05). Both cardiac output and cardiac efficiency in the esmolol-treated rats were significantly higher throughout the study periods vs. the control group (p < .05).

CONCLUSIONS

Esmolol infusion in sepsis improved oxygen utilization of myocardium and preserved myocardial function.