Pressors and Inotropes

A Guide to the Use of Vasopressors and Inotropes for Patients in Shock

Shock is a life-threatening circulatory failure that results in inadequate tissue perfusion and oxygenation. Vasopressors and inotropes are vasoactive medications that are vital in increasing systemic vascular resistance and cardiac contractility, respectively, in patients presenting with shock. To be well versed in using these agents is an important skill to have in the critical care setting where patients can frequently exhibit symptoms of shock. In this review, we will discuss the pathophysiological mechanisms of shock and evaluate the current evidence behind the management of shock with an emphasis on vasopressors and inotropes.

In Vivo Laser-Induced Vasoactive Microenvironmental Setting via a Stimuli-Responsive Microstructured Depot

A stimuli-responsive polymeric three-dimensional microstructured film (PTMF) is a 3D structure with an array of sealed chambers on its external surface. In this work, we demonstrate the use of PTMF as a laser-triggered stimulus-response system for local in vivo targeted blood vessels stimulation by vasoactive substances. The native vascular networks of the mouse mesentery were used as model tissues. Epinephrine and KCl were used as vasoactive agents that were sealed into individual chambers upon precipitation in the amount of pictograms. We demonstrated the method for non-damaged one-by-one chamber activation using a focused 532 nm laser light passed through biological tissues. To avoid laser-induced photothermal damage to biological tissues, the PTMF was functionalized with Nile Red dye, which effectively absorbs laser light. Chemically stimulated blood vessel fluctuations were analyzed using digital image processing methods. Hemodynamics changes were measured and visualized using the particle image velocimetry approach.

A randomized open label, parallel-group study to evaluate the hemodynamic effects of Cafedrine/Theodrenaline vs Noradrenaline in the treatment of intraoperative hypotension after induction of general anesthesia: the "HERO" study design and rationale

OBJECTIVE

Intraoperative arterial hypotension (IOH) is associated with poor patient outcome. This study aims to compare the hemodynamic effects of Cafedrine/Theodrenaline (C/T) and Noradrenaline (NA) for the treatment of hypotension in patients who develop IOH after anesthesia induction.

RESEARCH DESIGN AND METHODS

This is a national, randomized, parallel-group, multicenter, and open-label study. Adult patients (≥50 years, ASA-classification III-IV) who undergo elective surgery will be included. When IOH (MAP <70 mmHg) develops, C/T or NA will be given as a bolus injection ("bolus phase", 0-20 min after initial application) and subsequently as continuous infusion ("infusion phase", 21-40 min after initial application) to achieve MAP = 90 mmHg. Hemodynamic data are captured in real time by advanced hemodynamic monitoring.

RESULTS

Primary endpoints, i.e. the treatment-related difference in average mean arterial pressure (MAP) during the "infusion phase" and the treatment-related difference in average cardiac index during the "bolus phase" are assessed (fixed-sequence method). Non-inferiority of C/T compared to NA in achieving 90 mmHg (MAP) when applied as continuous infusion is hypothesized. In addition, superiority of C/T over NA, applied as bolus injection, in increasing cardiac index is postulated. It is estimated that 172 patients are required to establish statistical significance with a power of 90%. After adjusting for ineligibility and dropout rate, 220 patients will be screened.

CONCLUSION

This clinical trial will yield evidence for marketing authorization of C/T applied as continuous infusion. Additionally, the effects of C/T compared to NA on cardiac index will be assessed. First results of the "HERO"-study are expected in 2024. DRKS identifier: DRKS00028589. EudraCT identifier: 2021-001954-76.

Beyond Reperfusion: Acute Ventricular Unloading and Cardioprotection During Myocardial Infarction

Heart failure is a major cause of morbidity and mortality around the world, and myocardial infarction is its leading cause. Myocardial infarction destroys viable myocardium, and this dead tissue is replaced by a non-contractile scar that results in impaired cardiac function and a significantly increased likelihood of the patient developing heart failure. Limiting infarct scar size has been the target of pre-clinical and clinical investigations for decades. However, beyond reperfusion, few therapies have translated into the clinic that limit its formation. New approaches are needed. This review will focus on new clinical and pre-clinical data demonstrating that acute ventricular unloading prior to reperfusion by means of percutaneous left ventricular support devices reduces ischemia-reperfusion injury and limits infarct scar size. Emphasis will be given to summarizing our current mechanistic understanding of this new therapeutic approach to treating myocardial infarction.

Time delays associated with vasoactive medication preparation and delivery in simulated patients at risk of cardiac arrest

PURPOSE

To compare, quantify, and describe the time-delays associated with four common methods of adrenaline administration in the simulated setting of impending cardiac arrest.

METHODS

Using sham medication and a high-fidelity simulator, experienced Nurses prepared, then delivered, adrenaline by: i) bolus, ii) lower-concentration infusion iii) higher-concentration infusion, and iv) higher-concentration infusion plus carrier-line. We recorded medication preparation and delivery time, plus administration errors and self-reported competence.

RESULTS

Median total delay was i) 120s for bolus (95% CI 112-128s); ii) 179s for lower concentration infusion (95% CI 172-186s); iii) 296s for higher concentration infusion (95% CI 285-307s); and iv) 411s for higher concentration infusion plus carrier line (95% CI 399-423s). Time to prepare/deliver a bolus was less than any infusion (p<0.001). Time to prepare/deliver a lower-concentration infusion was less than either higher-concentration infusion (p<0.001). No substantial equipment failures or medication errors were observed. Participants reported high-competence. The majority of delay was from drug preparation not delivery.

CONCLUSIONS

We highlight potentially dangerous delays with administration of life-saving medications by all four methods. We should prioritize boluses, and focus on improving drug preparation times and human performance, more than drug delivery and equipment.

[Vasopressors and inotropes: use in paediatrics]

The cardiovascular system is a dynamic system, which is required to ensure adequate delivery of oxygen, nutrients, and hormones to the tissues that are necessary for cell metabolism. It also synthesises and modifies the vasoactive components that regulate vascular tone and myocardial function. These vasoactive components have demonstrated their beneficial effects in the management of paediatric patients in a critical condition with heart failure and shock. However, their use and abuse brings harmful effects, increases mortality, and is associated with arrhythmias. An increase in myocardial oxygen consumption favours the presence of ischaemia, therefore it is necessary to know the mechanism of action and indications of these drugs to minimise their harmful effects. The purpose of this review is to describe the pharmacology and clinical applications of inotropic and vasopressor agents in the paediatric patient in acritical condition.

Beneficial effect of medicinal plants on the contractility of post-hypoxic isolated guinea pig atria - Potential implications for the treatment of ischemic-reperfusion injury

Context Ischemic-reperfusion injury is accompanied by a decreased contractility of the myocardium. Positive-inotropic agents have proven useful for treating this condition but may exert serious side-effects. Objective In this study, aqueous preparations from Abelmoschus esculentus L. Moench (Malvaceae), Annona muricata L. (Annonaceae), Bixa orellana L. (Bixaceae), Cecropia peltata L. (Moraceae), Erythrina fusca Lour. (Fabaceae), Psidium guajava L. (Myrtaceae) and Terminalia catappa L. (Combretaceae) were evaluated for their ability to improve the decreased contractility of isolated guinea pig atria after hypoxic stress. Materials and methods Guinea pig atria isolated in Ringer-Locke buffer gassed with 100% O2 at 30 °C were exposed for 5 min to hypoxia, then allowed to recover in oxygenated buffer alone or containing a single plant extract (0.001-1 mg/mL). The contractility (g/s) and beating frequency (beats/min), as well as troponin C contents of the bathing solution (ng/mL), were determined and expressed as means ± SDs. Results The extracts of A. muricata, B. orellana, C. peltata and T. catappa caused an increase in the contractility compared to untreated atria of 340 ± 102%, 151 ± 13%, 141 ± 14% and 238 ± 44%, respectively. However, the latter two preparations increased the troponin C contents of the bathing solution to 36 ± 11 and 69 ± 33, compared to the value of 11 ± 3 ng/mL found with untreated atria. Conclusions Preparations from A. muricata and B. orellana may possess positive-inotropic properties which may improve the contractility of the post-hypoxic myocardium. Studies to assess their usefulness in ischemic-reperfusion injury are warranted.