Effect of non-adrenergic vasopressors on macro- and microvascular coupling in distributive shock

Resuscitating the macro- vs. microcirculation in septic shock

PURPOSE OF REVIEW

This review summarizes current literature about the relationships between macro and microcirculation and their practical clinical implications in children with septic shock.

RECENT FINDINGS

Current evidence from experimental and clinical observational studies in children and adults with septic shock reveals that the response to treatment and resuscitation is widely variable. Furthermore, there is a loss of hemodynamic coherence, as resuscitation-induced improvement in macrocirculation (systemic hemodynamic parameters) does not necessarily result in a parallel improvement in the microcirculation. Therefore, patient-tailored monitoring is essential in order to adjust treatment requirements during resuscitation in septic shock. Optimal monitoring must integrate macrocirculation (heart rate, blood pressure, cardiac output, and ultrasound images), microcirculation (videomicroscopy parameters and capillary refill time) and cellular metabolism (lactic acid, central venous blood oxygen saturation, and difference of central venous to arterial carbon dioxide partial pressure).

SUMMARY

There is a dire need for high-quality studies to assess the relationships between macrocirculation, microcirculation and tissue metabolism in children with septic shock. The development of reliable and readily available microcirculation and tissue perfusion biomarkers (other than lactic acid) is also necessary to improve monitoring and treatment adjustment in such patients.

Sub-therapeutic vasopressin but not therapeutic vasopressin improves gastrointestinal microcirculation in septic rats: A randomized, placebo-controlled, blinded trial

INTRODUCTION

Sepsis impairs gastrointestinal microcirculation and it is hypothesized that this might increase patient's mortality. Sub-therapeutic vasopressin improves gastric microcirculation under physiologic conditions whereas a therapeutic dosing regimen seems to be rather detrimental. However, the effects of sub-therapeutic vasopressin on gastrointestinal microcirculation in sepsis are largely unknown. Therefore, we conducted this trial to investigate the effect of sub-therapeutic as well as therapeutic vasopressin on gastrointestinal microcirculation in sepsis.

METHODS

40 male Wistar rats were randomized into 4 groups. Colon ascendens stent peritonitis (CASP)-surgery was performed to establish mild or moderate sepsis. 24 hours after surgery, animals received either vasopressin with increasing dosages every 30 min (6.75, 13.5 (sub-therapeutic), 27 mU · kg-1 · h-1 (therapeutic)) or vehicle. Microcirculatory oxygenation (μHBO2) of the colon was recorded for 90 min using tissue reflectance spectrophotometry. Intestinal microcirculatory perfusion (total vessel density (TVD; mm/mm2) and perfused vessel density (PVD; mm/mm2)) were measured using incident dark field-Imaging at baseline and after 60 min.

RESULTS

In mild as well as in moderate septic animals with vehicle-infusion intestinal μHbO2, TVD and PVD remained constant. In contrast, in moderate sepsis, sub-therapeutic vasopressin with 13.5 mU · kg-1 · h-1 elevated intestinal μHBO2 (+ 6.1 ± 5.3%; p < 0.05 vs. baseline) and TVD (+ 5.2 ± 3.0 mm/mm2; p < 0.05 vs. baseline). μHBO2, TVD and PVD were significantly increased compared to moderate sepsis alone. However, therapeutic vasopressin did not change intestinal microcirculation. In mild septic animals sub-therapeutic as well as therapeutic vasopressin had no relevant effect on gastrointestinal microcirculation. Systemic blood pressure remained constant in all groups.

CONCLUSION

Sub-therapeutic vasopressin improves gastrointestinal microcirculatory oxygenation in moderate sepsis without altering systemic blood pressure. This protective effect seems to be mediated by an enhanced microcirculatory perfusion and thereby increased oxygen supply. In contrast, therapeutic vasopressin did not show this beneficial effect.

Methylene blue for vasoplegic syndrome in cardiopulmonary bypass surgery: A systematic review and meta-analysis

BACKGROUND

To evaluate the benefit of methylene blue as an adjunct treatment by assessing hemodynamic, morbidity rate, intensive care unit length of stay, and mortality rate outcomes in adult patients with vasoplegic syndrome.

METHODS

A systematic search through electronic databases including Pubmed, Embase, Scopus, and Medline for studies assessing the use of methylene blue in patients with vasoplegic syndrome compared to control treatments. The Newcastle-Ottawa Scale tool was used for observational studies, and Jadad Scale was used for controlled trials to assess the risk of bias.

RESULTS

This systematic review included six studies for qualitative synthesis and five studies for quantitative synthesis. Pooled analysis revealed that mean arterial pressure, systemic vascular resistance, heart rate, and hospital stay were not statistically significant in methylene blue administration compared to control. However, administration of methylene blue in vasoplegic syndrome patients significantly reduces renal failure (OR = 0.25; 95% CI = 0.08-0.75), development of multiple organ failure (OR = 0.09; 95% CI = 0.02-0.51), and mortality rate (OR = 0.12; 95% CI = 0.03-0.46).

CONCLUSION

Adjunct administration of methylene blue for vasoplegic syndrome patients significantly reduces renal failure, multiple organ failure, and mortality.

Clinical Efficiency of Vasopressin or Its Analogs in Comparison With Catecholamines Alone on Patients With Septic Shock: A Systematic Review and Meta-Analysis

BACKGROUND

Vasopressin is an efficient remedy for septic shock patients as its great capacity in promoting hemodynamic stabilization. The aim of current systematic review and meta-analysis is to compare the clinical efficiency of vasopressin or its analogs with sole catecholamines on patients with septic shock.

METHODS

A systematic search of Cochrane Library, EMBASE, and PubMed online databases was performed up to 30 Oct 2019 to identify randomized controlled trials comparing use of vasopressin or its analogs (e.g., terlipressin, selepressin) with administration of catecholamines alone.

RESULTS

We included 23 RCTs with 4,225 patients in the current study. Compared with solely use of catecholamines, administration of vasopressin or its analogs was not associated with reduced 28-day or 30-day mortality among patients with septic shock [RR=0.94 (95% CI, 0.87-1.01), P=0.08, I2 = 0%]. The result of primary endpoint remained unchanged after conducting sensitivity analysis. Despite a significantly higher risk of digital ischemia in patients receiving vasopressin or its analogs [RR=2.65 (95% CI, 1.26-5.56), P < 0.01, I2 = 48%], there was no statistical significance in the pooled estimate for other secondary outcomes, including total adverse events, arrhythmia, acute myocardial infarction (AMI) and cardiac arrest, acute mesenteric ischemia, ICU/hospital length of stay, and mechanical ventilation (MV) duration.

CONCLUSIONS

The administration of vasopressin or its analogs was not associated with reduced 28-day or 30-day mortality among patients with septic shock, while an increased incidence of digital ischemia should be noted in patients receiving agonists for vasopressin receptors.