Double-Blind Placebo-Controlled Comparison of Enoximone and Dobutamine Infusions in Patients With Moderate to Severe Chronic Heart Failure

Venous return and mean systemic filling pressure: physiology and clinical applications

Venous return is the flow of blood from the systemic venous network towards the right heart. At steady state, venous return equals cardiac output, as the venous and arterial systems operate in series. However, unlike the arterial one, the venous network is a capacitive system with a high compliance. It includes a part of unstressed blood, which is a reservoir that can be recruited via sympathetic endogenous or exogenous stimulation. Guyton’s model describes the three determinants of venous return: the mean systemic filling pressure, the right atrial pressure and the resistance to venous return. Recently, new methods have been developed to explore such determinants at the bedside. In this narrative review, after a reminder about Guyton’s model and current methods used to investigate it, we emphasize how Guyton’s physiology helps understand the effects on cardiac output of common treatments used in critically ill patients.

Repetitive milrinone therapy in ambulatory advanced heart failure patients

BACKGROUND

Advanced heart failure (HF) patients usually poorly tolerate guideline-directed HF medical therapy (GDMT) and suffer high rates of morbidity and mortality. The use of continuous inotropes in the outpatient settings is hampered by previous data showing excess morbidity. We aimed to assess the safety and efficacy of repetitive, intermittent, short-term intravenous milrinone therapy in advanced HF patients with an intention to introduce and up-titrate GDMT and improve functional class.

HYPOTHESIS

Repetitive, intermittent milrinone therapy may assist with the stabilization of advanced HF patients.

METHODS

Advanced HF patients treated with beta-blockers and implanted with defibrillators were initiated with repetitive, intermittent short-term intravenous milrinone therapy at our HF outpatient unit. Patients were prospectively followed with defibrillator interrogation, functional class assessment, B-natriuretic peptide (BNP) levels, and echocardiography parameters.

RESULTS

The cohort included 24 patients with a mean 330 ± 240 days of milrinone therapy exposure. Mean age was 73 ± 6 years with male predominance (96%). Following milrinone therapy, median BNP levels decreased significantly (882 [286-3768] to 631 [278-1378] pg/ml, p = .017) with a significant reduction in the number of patients with New York Heart Association (NYHA) Class III and IV (p = .012, 0.013) and an increase in number of patients on GDMT. Importantly, the number of total sustained ventricular tachycardia events and HF hospitalizations did not change.

CONCLUSIONS

In this small cohort of advanced HF, repetitive, intermittent, short-term milrinone therapy was found to be safe and potentially efficacious.

Enoximone in status asthmaticus

Bronchial asthma is a chronic disease affecting >300 million people worldwide [1]. The most severe disease manifestation is status asthmaticus, which can be unresponsive to medical therapy. Patients with severe status asthmaticus who require intubation and mechanical ventilation have mortality rates of up to 20% [2]. Airflow obstruction is often so severe that adequate decarboxylation and protective ventilation are not feasible, and extracorporeal membrane oxygenation (ECMO) support is nowadays an established treatment option as a bridge to recovery [3, 4].

In a patient with severe status asthmaticus, enoximone, a phosphodiesterase-3 inhibitor, caused immediate bronchodilationhttp://bit.ly/38UYpUn

Preliminary results of the Multicenter Observational Study with Enoximone in Cardiac surgery (MOSEC)

BACKGROUND

Perioperative administration of Enoximone has been shown to improve hemodynamics, organ function, and inflammatory response. Aim of the present study was to evaluate the effects of Enoximone after on-pump cardiac surgery.

METHODS

A protocol for a multicenter observational study was reviewed and approved by local ethic committee. This preliminary report involves the first 29 patients enrolled, in whom Enoximone was perioperatively administered in the context of on-pump cardiac surgery. All patients enrolled were propensity-matched 1:1 with controls not receiving Enoximone, renal function was evaluated in terms of estimated glomerular filtration rate (eGFR) with the CKD-EPI equation.

RESULTS

After propensity matching, the two cohorts of patients receiving Enoximone or not did not show any significant differences among baseline characteristics. Patients receiving Enoximone showed a progressive improvement of eGFR at each time-point of follow-up: roughly +4.3, +10.0, and +12.3 mL/min/1.73 m² on postoperative days 2, 7, and 30; respectively. Consistently, maximum difference versus baseline was +12.6 mL/min/1.73 m² (or +19.3%) among Enoximone patients vs +3.3 mL/min/1.73 m² (or +4.4%) among controls (p = 0.02). Multivariable regression analysis (R²-adjusted 0.47) showed only age (β -0.53; p = 0.01), preoperative eGFR (β -0.39; p = 0.02), diabetes (β 2.1; p = 0.01), cardio-pulmonary bypass duration (β 0.08; p = 0.05), and Enoximone administration (β -0.74; p = 0.05) to be independently correlated with delta eGFR variation on day 30.

CONCLUSION

These preliminary results show that perioperative Enoximone administration improved renal function in patients undergoing on-pump cardiac surgery. Further studies are needed to confirm these findings.

Cardiac Myosin Activators in Systolic Heart Failure: More Friend than Foe?

Despite the rising prevalence of HF, new evidence-based novel therapies for patients with worsening HF remain lacking, e.g., safe inotropic therapies. Traditional inotropes increase contractility by altering intracellular calcium flux, a pathway that may be responsible for the multitude of adverse effects associated with current options. Omecamtiv mecarbil, a direct myosin activator, increases contractility through a distinct pathway by increasing the proportion of myosin heads that are bound to actin in a high-affinity state. Phase II clinical trials in patients with chronic HF with this agent seem promising. A phase III trial investigating this therapy has not yet been pursued to date.

Perioperative administration of enoximone and renal function after cardiac surgery: a propensity-matched analysis

BACKGROUND

Perioperative administration of enoximone has been shown to improve hemodynamics, organ function, and inflammatory response. Aim of the present study is to evaluate the impact of enoximone on postoperative renal function after on-pump cardiac surgery.

METHODS

A total of 3727 patients undergoing cardiac surgery at one Institution between May 2004 and November 2010 were reviewed. A propensity score was built and a 1:1 perfect matching was performed, providing two fairly comparable cohorts of 712 patients each, receiving or not enoximone after surgery. Renal function was evaluated by lower glomerular filtration rate (GFR) value reached postoperatively.

RESULTS

Overall 30-day mortality rate was 4.3% (62/1424). Cumulative incidence of postoperative renal failure (RF) was 157/1424(11%), of which 99/1424(7%) needed renal replacement therapy. Mean lower postoperative GFR in patients who received or not enoximone was 63 ± 30.1 and 53.5 ± 26.1 ml/min/1.73 m(2) (p<0.0001), respectively. At multivariable analysis age (OR2.75, p=0.0004), diabetes (OR1.82, p=0.006), preoperative GFR (OR3.81, p<0.0001), preoperative cardiogenic shock (OR1.65, p=0.004), previous cardiac surgery (OR2.12, p=0.0002), type of intervention (OR1.96, p=0.005), and enoximone (OR0.38, p=0.001) were found to be independently associated with postoperative RF. Logistic regression analysis showed that the administration of enoximone (OR0.41, p=0.0001), and of no inotropes (OR0.27, p<0.0001) were protective vs. the occurrence of postoperative RF.

CONCLUSION

Patients perioperatively receiving enoximone showed a statistically significant better renal function after cardiac surgery.

Inotropic drugs and their uses in critical care

The aim of this article was to provide a resource for critical care nurses wishing to further their understanding of inotropic drugs used in critical care. The physiology of cardiac output and blood pressure is examined along with an explanation of adrenergic receptors acted on by inotropes. Some common indications for inotropic therapy are discussed, along with essential patient monitoring and dose calculations to ensure safe therapeutic ranges are observed. Some of the most commonly used positive inotropes used in critical care environments are individually explored, providing indications and some of the latest research relating to their uses. Frequently, observed side effects of individual inotropes are also offered, enabling the nurse to maintain patient safety when administering these potent drugs. Some major nursing and professional issues related to inotrope therapy and medicine administration are discussed, as well as some recommended practices in renewing infusions.