The Effect of Propofol and Dexmedetomidine Sedation on Norepinephrine Requirements in Septic Shock Patients: A Crossover Trial

Cardiovascular Safety of Clonidine and Dexmedetomidine in Critically Ill Patients after Cardiac Surgery

Purpose

The aim of this retrospective study was to assess the haemodynamic adverse effects of clonidine and dexmedetomidine in critically ill patients after cardiac surgery.

Methods

2769 patients were screened during the 30-month study period. Heart rate (HR), mean arterial pressure (MAP), and norepinephrine requirements were assessed 3-hourly during the first 12 hours of the continuous drug infusion. Results are given as median (interquartile range) or numbers (percentages).

Results

Patients receiving clonidine (n = 193) were younger (66 (57-73) vs 70 (63-77) years, p=0.003) and had a lower SAPS II (35 (27-48) vs 41 (31-54), p=0.008) compared with patients receiving dexmedetomidine (n = 141). At the start of the drug infusion, HR (90 (75-100) vs 90 (80-105) bpm, p=0.028), MAP (70 (65-80) vs 70 (65-75) mmHg, p=0.093), and norepinephrine (0.05 (0.00-0.11) vs 0.12 (0.03-0.19) mcg/kg/min, p < 0.001) were recorded in patients with clonidine and dexmedetomidine. Bradycardia (HR < 60 bpm) developed in 7.8% with clonidine and 5.7% with dexmedetomidine (p=0.51). Between baseline and 12 hours, norepinephrine remained stable in the clonidine group (0.00 (-0.04-0.02) mcg/kg/min) and decreased in the dexmedetomidine group (-0.03 (-0.10-0.02) mcg/kg/min, p=0.007).

Conclusions

Dexmedetomidine and the low-cost drug clonidine can both be used safely in selected patients after cardiac surgery.

Protective effects of dexmedetomidine on the survival of random flaps

BACKGROUND

Random flaps can be used to repair wounds and improve shape and functional reconstruction, but inflammation and necrosis limit their application. Modified McFarlane flap models were constructed on the backs of rats. We hypothesized that dexmedetomidine (DEX) could improve the survival rate of ischemic random flaps.

METHODS

Sixty rats were randomly divided into three groups: a low-dose DEX group (DEX-L group, 10 μg/kg/D), a high-dose DEX group (DEX-H group, 20 μg/kg/D) and a control group (0.9 % saline equivalent). On day 7 after flap construction, the survival percentage of the flap model was calculated. Hematoxylin and eosin staining (H&E) was used to evaluate the histopathological status of the flaps and microvessel density (MVD). Lead oxide/gelatin angiography was used to detect angiogenesis, and laser Doppler flow imaging (LDF) was used to detect blood perfusion. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in the middle areas of the flaps were measured to show the level of oxidative stress. The expressions of Toll-like receptor (TLR4), nuclear factor-kappa B (NF-κB), interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) were detected by immunohistochemistry.

RESULTS

DEX significantly increased the average survival percentage of the flaps and reduced ischemia and necrosis of the distal end of the flaps. SOD activity significantly increased, while MDA significantly decreased, indicating that DEX reduces oxidative damage. The expression of inflammatory immunoregulatory proteins (TLR4, NF-κB) was downregulated, and the levels of inflammatory factors (IL-1β, IL-6 and TNF-α) were lower. In addition, DEX upregulated VEGF expression, promoted angiogenesis, and increased blood perfusion.

CONCLUSION

In random flap transplantation, a high dose of DEX is beneficial to flap survival.

Dexmedetomidine Improves Cardiovascular and Ventilatory Outcomes in Critically Ill Patients: Basic and Clinical Approaches

Dexmedetomidine (DEX) is a highly selective α2-adrenergic agonist with sedative and analgesic properties, with minimal respiratory effects. It is used as a sedative in the intensive care unit and the operating room. The opioid-sparing effect and the absence of respiratory effects make dexmedetomidine an attractive adjuvant drug for anesthesia in obese patients who are at an increased risk for postoperative respiratory complications. The pharmacodynamic effects on the cardiovascular system are known; however the mechanisms that induce cardioprotection are still under study. Regarding the pharmacokinetics properties, this drug is extensively metabolized in the liver by the uridine diphosphate glucuronosyltransferases. It has a relatively high hepatic extraction ratio, and therefore, its metabolism is dependent on liver blood flow. This review shows, from a basic clinical approach, the evidence supporting the use of dexmedetomidine in different settings, from its use in animal models of ischemia-reperfusion, and cardioprotective signaling pathways. In addition, pharmacokinetics and pharmacodynamics studies in obese subjects and the management of patients subjected to mechanical ventilation are described. Moreover, the clinical efficacy of delirium incidence in patients with indication of non-invasive ventilation is shown. Finally, the available evidence from DEX is described by a group of Chilean pharmacologists and clinicians who have worked for more than 10 years on DEX.

Hemodynamic Effects of Propofol and Dexmedetomidine in Septic Patients Without Shock

Background: Use of nonbenzodiazepine agents propofol and dexmedetomidine are first line for sedation in the intensive care unit (ICU). These agents have been implicated in the development of bradycardia and hypotension in critical illness. Objectives: To compare the development of clinically significant hypotension and/or bradycardia (ie, negative hemodynamic event) in adults with sepsis yet to require vasopressors receiving either propofol or dexmedetomidine for continuous sedation. Methods: This was a retrospective multicenter cohort study of adults with non-vasopressor-dependent sepsis admitted to an ICU at two academic medical centers between July 2013-September 2017. Results: Patients in the propofol (n = 64) and dexmedetomidine (n = 31) groups developed a clinically significant negative hemodynamic event at statistically similar frequencies (34.4% vs 16.1%, P = 0.065). Patients receiving propofol developed a larger degree of hypotension (47.3 vs 34.7 mm Hg reduction, P = 0.031). In multivariable logistic regression modeling, independent predictors of a negative hemodynamic event were a past medical history of chronic kidney disease (odds ratio [OR] = 3.8; 95% CI = 1.17-12.2; P = 0.027) and baseline heart rate (OR = 1.02; 95% CI = 1.00-1.10; P = 0.036). Conclusions and Relevance: A minority of patients with sepsis who received either propofol or dexmedetomidine experienced an event. Patients with sepsis without shock receiving continuous infusions of propofol and dexmedetomidine experienced a negative hemodynamic event at similar frequencies, though the degree of hypotension seen with propofol was greater. The clinical significance of these adverse effects requires cautious use in sepsis and further investigation.

The effect of dexmedetomidine and clonidine on the inflammatory response in critical illness: a systematic review of animal and human studies

Background

The α2 agonists, dexmedetomidine and clonidine, are used as sedative drugs during critical illness. These drugs may have anti-inflammatory effects, which might be relevant to critical illness, but a systematic review of published literature has not been published. We reviewed animal and human studies relevant to critical illness to summarise the evidence for an anti-inflammatory effect from α2 agonists.

Methods

We searched PubMed, the Cochrane library, and Medline. Animal and human studies published in English were included. Broad search terms were used: dexmedetomidine or clonidine, sepsis, and inflammation. Reference lists were screened for additional publications. Titles and abstracts were screened independently by two reviewers and full-text articles obtained for potentially eligible studies. Data extraction used a bespoke template given study diversity, and quality assessment was qualitative.

Results

Study diversity meant meta-analysis was not feasible so descriptive synthesis was undertaken. We identified 30 animal studies (caecal ligation/puncture (9), lipopolysaccharide (14), acute lung injury (5), and ischaemia-reperfusion syndrome (5)), and 9 human studies. Most animal (26 dexmedetomidine, 4 clonidine) and all human studies used dexmedetomidine. In animal studies, α2 agonists reduced serum and/or tissue TNFα (20 studies), IL-6 (17 studies), IL-1β (7 studies), NFκB (6 studies), TLR4 (6 studies), and a range of other mediators. Timing and doses varied widely, but in many cases were not directly relevant to human sedation use. In human studies, dexmedetomidine reduced CRP (4 studies), TNFα (5 studies), IL-6 (6 studies), IL-1β (3 studies), and altered several other mediators. Most studies were small and low quality. No studies related effects to clinical outcomes.

Conclusion

Evidence supports potential anti-inflammatory effects from α2 agonists, but the relevance to clinically important outcomes is uncertain. Further work should explore whether dose relationships with inflammation and clinical outcomes are present which might be separate from sedation-mediated effects.

Pharmacologic Considerations Surrounding Sedation, Delirium, and Sleep in Critically Ill Adults: A Narrative Review

INTRODUCTION

Agitation, delirium, and sleep dysfunction in the intensive care unit (ICU) are common occurrences that result in negative patient outcomes. With the recent publication of the 2018 Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption in Adult Patients in the ICU (PAD-IS), several areas are of particular interest due to emerging literature or conflicting results of research.

OBJECTIVE

To highlight areas where emerging literature or variable study results exist and to provide the clinician with recommendations regarding patient management.

METHODS

The 2018 PAD-IS guidelines were reviewed, and areas of emerging literature or lack of consensus of included investigations surrounding pharmacologic management of sedation, delirium, and sleep in the ICU were identified. A review and appraisal of the literature was conducted specifically to address the identified areas. Prospective, randomized trials were included in this narrative review.

RESULTS

Four areas with emerging data or conflicting evidence were identified and included: use of propofol or dexmedetomidine for sedation, pharmacologic prevention of delirium, treatment of delirium, and pharmacologic strategies to improve sleep.

CONCLUSION

A comprehensive approach to the prevention and management of delirium, sedation, and sleep in the ICU is necessary to optimize patient outcomes.