Vasopressor use in septic shock: an update

The initial resuscitation of septic shock

Septic shock is the most severe form of sepsis, characterized by (a) persistent hypotension despite fluid resuscitation and (b) the presence of tissue hypoperfusion. Delays in the diagnosis and initiation of treatment of septic shock is associated with increasing risk for mortality. Early and effective fluid resuscitation and vasopressor administration play a crucial role in maintaining tissue perfusion in septic shock patients. A low diastolic arterial pressure (DAP) correlates with severity of arteriolar vasodilation, compromises left ventricle oxygen supply and can be used for identifying septic shock patients that would potentially benefit from earlier vasopressor therapy. Controversy currently exists as to the balance of fluids and vasopressors to maintain target mean arterial pressure. The aim of this article is to review the rationale for fluid resuscitation and vasopressor therapy and the importance of both mean and diastolic blood pressure during the initial resuscitation of the septic shock. We relate our personal prescription of balancing fluids and vasopressors in the resuscitation of septic shock.

Dihydromyricetin improves vascular hyporesponsiveness in experimental sepsis via attenuating the over-excited MaxiK and KATP channels

CONTEXT

Dihydromyricetin (DMY) has oxidation resistance, anti-inflammatory and free radical scavenging capabilities. The preventive effects of DMY for vascular hyporeactivity remain unclear.

OBJECTIVE

This study investigates the preventive effects of DMY in vascular hyporeactivity.

MATERIALS AND METHODS

The experimental sepsis was induced by transvenous administration of lipopolysaccharide (LPS) to Sprague-Dawley (SD) rats. DMY-treated rats received daily administration of DMY, 5 μg/kg dissolved in DMSO through the tail vein for 7 days. The invasive mean arterial pressure (MAP) of the caudal ventral artery was measured. Dose-response curves for norepinephrine (NE, doses from 10^-9 to 10^-6M) were obtained in isolated thoracic aorta in a cumulative manner. The function of MaxiK and K_ATP channels were investigated using whole-cell patch clamp recording. The Elisa was adopted to measure the serum concentration of NO, MDA, 3-NT, IL-1β and TNF-α.

RESULTS

The increased MAP in septic rats induced by vasopressor agents was smaller than that in control rats. However, the % of increased MAP induced by vasopressor agents was raised by DMY injection (NE: 20.4 ± 8.495 vs. 15.16 ± 5.195%; AVP: 14.05 ± 2.459 vs. 9.583 ± 2.982%, p < 0.05). The vascular hyporesponsiveness to NE (10^-6M) in vitro. was increased by 51% in LPS + DMY group compared with that in LPS + Con group (2.74 ± 0.81 vs. 1.82 ± 0.92 g, p < 0.05). Charybdotoxin (a potent MaxiK channel blocker) and glibenclamide (a K_ATP channel blocker) pretreatment, instead of 4-aminopyridine (4-AP) and BaCl₂, could diminish the DMY-induced improvement of vasoconstrictor hyporeactivity (ChTX: 73.2 ± 11.8 vs. 71.8 ± 13.5%; Glib: 63.1 ± 12.5 vs. 58.1 ± 13.7%, p > 0.05). DMY blunted the highly sensitized MaxiK and K_ATP channels of arterial smooth muscle cells isolated from the thoracic aorta of LPS rats. DMY decreased the serum level of NO, MDA, IL-1β and TNF-α, which had increased in LPS rats.

DISCUSSION AND CONCLUSIONS

Our results indicate that DMY administration ameliorated the impaired contractility of the rat aorta in experimental sepsis. Such an effect is mediated by normalization of the over-excited MaxiK and K_ATP, channels possibly via oxidative stress inhibition.

C-Type Natriuretic Peptide Induces Anti-contractile Effect Dependent on Nitric Oxide, Oxidative Stress, and NPR-B Activation in Sepsis

AIMS

To evaluate the role of nitric oxide, reactive oxygen species (ROS), and natriuretic peptide receptor-B activation in C-type natriuretic peptide-anti-contractile effect on Phenylephrine-induced contraction in aorta isolated from septic rats.

METHODS AND RESULTS

Cecal ligation and puncture (CLP) surgery was used to induce sepsis in male rats. Vascular reactivity was conducted in rat aorta and resistance mesenteric artery (RMA). Measurement of survival rate, mean arterial pressure (MAP), plasma nitric oxide, specific protein expression, and localization were evaluated. Septic rats had a survival rate about 37% at 4 h after the surgery, and these rats presented hypotension compared to control-operated (Sham) rats. Phenylephrine-induced contraction was decreased in sepsis. C-type natriuretic peptide (CNP) induced anti-contractile effect in aortas. Plasma nitric oxide was increased in sepsis. Nitric oxide-synthase but not natriuretic peptide receptor-B expression was increased in septic rat aortas. C-type natriuretic peptide-anti-contractile effect was dependent on nitric oxide-synthase, ROS, and natriuretic peptide receptor-B activation. Natriuretic peptide receptor-C, protein kinase-Cα mRNA, and basal nicotinamide adenine dinucleotide phosphate (NADPH)-dependent ROS production were lower in septic rats. Phenylephrine and CNP enhanced ROS production. However, stimulated ROS production was low in sepsis.

CONCLUSION

CNP induced anti-contractile effect on Phenylephrine contraction in aortas from Sham and septic rats that was dependent on nitric oxide-synthase, ROS, and natriuretic peptide receptor-B activation.

Vasopressors for hypotensive shock

BACKGROUND

Initial goal-directed resuscitation for hypotensive shock usually includes administration of intravenous fluids, followed by initiation of vasopressors. Despite obvious immediate effects of vasopressors on haemodynamics, their effect on patient-relevant outcomes remains controversial. This review was published originally in 2004 and was updated in 2011 and again in 2016.

OBJECTIVES

Our objective was to compare the effect of one vasopressor regimen (vasopressor alone, or in combination) versus another vasopressor regimen on mortality in critically ill participants with shock. We further aimed to investigate effects on other patient-relevant outcomes and to assess the influence of bias on the robustness of our effect estimates.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015 Issue 6), MEDLINE, EMBASE, PASCAL BioMed, CINAHL, BIOSIS and PsycINFO (from inception to June 2015). We performed the original search in November 2003. We also asked experts in the field and searched meta-registries to identify ongoing trials.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing various vasopressor regimens for hypotensive shock.

DATA COLLECTION AND ANALYSIS

Two review authors abstracted data independently. They discussed disagreements between them and resolved differences by consulting with a third review author. We used a random-effects model to combine quantitative data.

MAIN RESULTS

We identified 28 RCTs (3497 participants) with 1773 mortality outcomes. Six different vasopressors, given alone or in combination, were studied in 12 different comparisons.All 28 studies reported mortality outcomes; 12 studies reported length of stay. Investigators reported other morbidity outcomes in a variable and heterogeneous way. No data were available on quality of life nor on anxiety and depression outcomes. We classified 11 studies as having low risk of bias for the primary outcome of mortality; only four studies fulfilled all trial quality criteria.In summary, researchers reported no differences in total mortality in any comparisons of different vasopressors or combinations in any of the pre-defined analyses (evidence quality ranging from high to very low). More arrhythmias were observed in participants treated with dopamine than in those treated with norepinephrine (high-quality evidence). These findings were consistent among the few large studies and among studies with different levels of within-study bias risk.

AUTHORS' CONCLUSIONS

We found no evidence of substantial differences in total mortality between several vasopressors. Dopamine increases the risk of arrhythmia compared with norepinephrine and might increase mortality. Otherwise, evidence of any other differences between any of the six vasopressors examined is insufficient. We identified low risk of bias and high-quality evidence for the comparison of norepinephrine versus dopamine and moderate to very low-quality evidence for all other comparisons, mainly because single comparisons occasionally were based on only a few participants. Increasing evidence indicates that the treatment goals most often employed are of limited clinical value. Our findings suggest that major changes in clinical practice are not needed, but that selection of vasopressors could be better individualised and could be based on clinical variables reflecting hypoperfusion.

Norepinephrine infusion increases urine output in children under sedative and analgesic infusion

Objective: to evaluate the effects of early norepinephrine (NE) infusion in children submitted to mechanical ventilation (MV) requiring continuous sedative and analgesic infusion. Methods: double-blinded, randomized, placebo-controlled trial enrolling children (1 month to 12 years of age) admitted to a Brazilian PICU and expected to require MV and continuous sedative and analgesic drug infusions for at least five days. Children were randomized to receive either norepinephrine (NE) (0.15 mcg/kg/min) or normal saline infusion, started in the first 24 hours of MV, and maintained for 72 hours. We compared hemodynamic variables, fluid intake, renal function and urine output between groups. Results: forty children were equally allocated to the NE or placebo groups, with no differences in baseline characteristics, laboratorial findings, PRISM II score, length of MV, or mortality between groups. The average norepinephrine infusion was 0.143 mcg/kg/min. The NE group showed higher urine output (p = 0.016) and continuous increment in the mean arterial pressure compared to the baseline (p = 0.043). There were no differences in the remaining hemodynamic variables, fluid requirements, or furosemide administration. Conclusion: early norepinephrine infusion in children submitted to MV improves mean arterial pressure and increases urine output. These effects were attributed to reversion of vasoplegia induced by the sedative and analgesic drugs.

Clinical trials comparing norepinephrine with vasopressin in patients with septic shock: a meta-analysis

BACKGROUND

The effect of norepinephrine in patients with septic shock remains controversial. We conducted a meta-analysis to compare the mortality rates and benefits of norepinephrine and vasopressin.

METHODS

PubMed, EMBASE, and the Cochrane Library database were searched from database inception to December 2013. We selected randomized controlled trials in adults with septic shock and compared norepinephrine with vasopressin. After assessing the heterogeneity of treatment effects across trials using the I (2) statistic, we used a fixed effects model (P ≥ 0.1) and expressed the results as risk ratios (RRs) for dichotomous outcomes or as standardized mean differences (SMDs) for continuous data with 95% confidence intervals (CIs). Meta-analysis was conducted using Review Manager 5.1 software.

RESULTS

Seven trials (n = 2323) met the inclusion criteria. Overall, the mortality rate in these seven trials was 36.2% (840/2323). There was no difference in mortality following the use of norepinephrine or vasopressin (RR 1.07; 95%CI 0.97-1.20; P = 0.19). Compared to norepinephrine, vasopressin had no significant effect on heart rate (HR) (SMD 0.21; 95%CI -0.08-0.50; P = 0.15), mean arterial pressure (MAP) (SMD 0.15; 95%CI -0.15-0.44; P = 0.33), cardiac index (CI) (SMD -0.10; 95%CI -0.64-0.44; P = 0.73), systemic vascular resistance index (SVRI) (SMD 0.15; 95%CI -0.39-0.70; P = 0.58), oxygen delivery (DO2) (SMD -0.06; 95%CI -0.62-0.49; P = 0.82), oxygen consumption (VO2) (SMD 0.03; 95%CI -0.52-0.59; P = 0.91) or lactic acid (SMD 0.07; 95%CI -0.23-0.36; P = 0.66). No significant heterogeneity was found in these comparisons (P ≥ 0.1).

CONCLUSIONS

There is not sufficient evidence to prove conclusively that norepinephrine is superior to vasopressin in terms of mortality and hemodynamics. The effects of norepinephrine and vasopressin on patients with septic shock require further study in large randomized controlled trials.

Cardiac peroxisome proliferator-activated receptor δ (PPARδ) as a new target for increased contractility without altering heart rate

Background and Aims

Agents having a positive inotropic effect on the heart are widely used for the treatment of heart failure. However, these agents have the side effect of altering heart rate. It has been established that peroxisome proliferator-activated receptor δ (PPARδ) is mediated in cardiac contraction, however the effect on heart rate is unknown. Thus, we used an agonist of PPARδ, GW0742, to investigate this issue in the present study.

Methods and Results

We used isolated hearts in Langendorff apparatus and hemodynamic analysis in catheterized rats to measure the actions of GW0742 extra-vivo and in vivo. In diabetic rats with heart failure, GW0742 at a dose sufficient to activate PPARδ reversed cardiac contraction without changes in heart rate. In normal rats, PPARδ enhanced cardiac contractility and hemodynamic dP/dt_max significantly more than dobutamine. Both actions were diminished by GSK0660 at a dose enough to block PPARδ. However, GW0742 at the same dose failed to modify heart rate, although it did produce a mild increase in blood pressure. Detection of intracellular calcium level and Western blotting analysis showed that the intracellular calcium concentration and troponin I phosphorylation were both enhanced by GW0742.

Conclusion

Activation of PPARδ by GW0742 increases cardiac contractility but not heart rate. Thus, PPARδ may be a suitable target for the development of inotropic agents to treat heart failure without changing heart rate.

Cardiovascular management of septic shock in 2012

Septic shock is a major cause of morbidity and mortality throughout the world. Source control, antimicrobial therapy, early goal-directed fluid resuscitation, and infusion of vasoactive pharmaceuticals remain the cornerstones of treatment. However, the cardiovascular management of septic shock is evolving. Basic science and clinical researchers have identified novel drug targets and are testing the efficacy of new therapeutic agents. For example, prevention of microvascular leak during septic shock is the focus of active investigations and may soon provide considerable benefit to patients. Among the important topics that will be discussed in this review are the following: the role of vascular endothelial dysfunction in microvascular leak, the impact of cytokines upon structural and functional proteins within the endothelial barrier and within the heart, and the ability of selective vasopressin 1a receptor agonists to minimize tissue edema and improve hemodynamic status.

Vasopressors for hypotensive shock

BACKGROUND

Initial goal directed resuscitation for shock usually includes the administration of intravenous fluids, followed by initiating vasopressors. Despite obvious immediate effects of vasopressors on haemodynamics their effect on patient relevant outcomes remains controversial. This review was originally published in 2004 and was updated in 2011.

OBJECTIVES

Our primary objective was to assess whether particular vasopressors reduce overall mortality, morbidity, and health-related quality of life.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 2), MEDLINE, EMBASE, PASCAL BioMed, CINAHL, BIOSIS, and PsycINFO (from inception to March 2010). The original search was performed in November 2003. We also asked experts in the field and searched meta-registries for ongoing trials.

SELECTION CRITERIA

Randomized controlled trials comparing various vasopressor regimens for hypotensive shock.

DATA COLLECTION AND ANALYSIS

Two authors abstracted data independently. Disagreement between the authors was discussed and resolved with a third author. We used a random-effects model for combining quantitative data.

MAIN RESULTS

We identified 23 randomized controlled trials involving 3212 patients, with 1629 mortality outcomes. Six different vasopressors, alone or in combination, were studied in 11 different comparisons.All 23 studies reported mortality outcomes; length of stay was reported in nine studies. Other morbidity outcomes were reported in a variable and heterogeneous way. No data were available on quality of life or anxiety and depression outcomes. We classified 10 studies as being at low risk of bias for the primary outcome mortality; only four studies fulfilled all trial quality items.In summary, there was no difference in mortality in any of the comparisons between different vasopressors or combinations. More arrhythmias were observed in patients treated with dopamine compared to norepinephrine. Norepinephrine versus dopamine, as the largest comparison in 1400 patients from six trials, yielded almost equivalence (RR 0.95, 95% confidence interval 0.87 to 1.03). Vasopressors used as add-on therapy in comparison to placebo were not effective either. These findings were consistent among the few large studies as well as in studies with different levels of within-study bias risk.

AUTHORS' CONCLUSIONS

There is some evidence of no difference in mortality between norepinephrine and dopamine. Dopamine appeared to increase the risk for arrhythmia. There is not sufficient evidence of any difference between any of the six vasopressors examined. Probably the choice of vasopressors in patients with shock does not influence the outcome, rather than any vasoactive effect per se. There is not sufficient evidence that any one of the investigated vasopressors is clearly superior over others.

Adrenergic support in septic shock: a critical review

The definition of septic shock includes sepsis-induced hypotension despite adequate fluid resuscitation, along with the presence of organ perfusion abnormalities, and ultimately cell dysfunction. To restore adequate organ perfusion and cell homeostasis, cardiac output should be restored with volume infusion plus vasopressor agents as indicated. Appropriate arterial pressure for each individual patient and proper arterial oxygen content are key elements to restoring perfusion. Tissue perfusion can be monitored by markers of organ and mitochondrial function, namely urine output, level of consciousness, peripheral skin perfusion, central or mixed venous oxygen saturation, and lactate. The hemodynamic effects of the different vasopressor agents depend on the relative affinity to adrenergic receptors. Those with predominant alpha-agonist activity produce more vasoconstriction (inoconstrictors) while those with predominant beta-agonist stimulation increase cardiac performance (inodilators). The debate about whether one vasopressor agent is superior to another is still ongoing. The Surviving Sepsis Campaign guidelines refer to either norepinephrine or dopamine as the first-choice vasopressor agent to correct hypotension in septic shock. However, recent data from observational and controlled trials have challenged these recommendations concerning different adrenergic agents. As a result, our view on the prescription of vasopressors has changed from a probably oversimplified "one-size-fits-all" approach to a multimodal approach in vasopressor selection.

Pharmacological optimization of tissue perfusion

After fluid resuscitation, vasoactive drug treatment represents the major cornerstone for correcting any major impairment of the circulation. However, debate still rages as to the choice of agent, dose, timing, targets, and monitoring modalities that should optimally be used to benefit the patient yet, at the same time, minimize harm. This review highlights these areas and some new pharmacological agents that broaden our therapeutic options.