Knowing the ropes of vasopressor dosing: a focus on norepinephrine

Analysis of the heterogeneous treatment effect of vasoactive drug dosage and time on hospital mortality across different sepsis phenotypes: a retrospective cohort study

BACKGROUND

The heterogeneity of sepsis poses challenges for the individualized treatment of vasoactive drugs.

METHODS

This study used data from ICUs in MIMIC-IV (2008-2019) and eICU (2014-2015) databases, identified sepsis by sepsis-3 criteria, and stratified sepsis into phenotypes by consensus K-means. The norepinephrine equivalence (NEE) formula balance treatment of different vasoactive drugs, with NEE captured hourly for up to 72 h to record both time of use and dosage. The logistic regression model, including phenotype-dosage-time interactions, examined heterogeneous treatment effects on hospital mortality. To address confounding, three models were fitted: Model 1 unadjusted, Model 2 adjusted for age and sex, and Model 3 additionally included 7 clinical variables identified via machine learning and directed acyclic graph. Nonlinear dosage was further analyzed based on restricted cubic splines. P values and P for interaction were Bonferroni-adjusted.

RESULTS

A total of 54,673 sepsis patients were included for phenotype identification, and 8,803 patients were further analyzed to evaluate heterogeneous treatment effect of vasoactive drugs. Four sepsis phenotypes were identified: A, B, C and D. Phenotype D was the most severe subgroup, followed by phenotype C, while phenotypes A and B were mild subgroups. In Model 3, each 0.05 μg/kg/min increase in NEE dosage was linked to higher hospital mortality (OR 1.328, 95% CI 1.314-1.342; p < 0.001). Longer NEE time of use also significantly increased mortality risk (OR 1.006, 95% CI 1.005-1.007; p < 0.001). In addition, these associations varied significantly by phenotype (P for interaction < 0.001). In RCS model, phenotype A consistently showed higher mortality than the other phenotypes at NEE dosages of 0.1-0.5 µg/kg/min, with this gap increasing over time, showing a clear dosage-time dependence. Phenotype B displayed lower overall mortality but the steepest relative risk of hospital mortality increased as dosage and time (OR of dosage: 1.309; OR of time: 1.005) in Model 3. Phenotype C reached the highest mortality risk when dosages exceeded 0.5 µg/kg/min, which was dosage dependence. Finally, phenotype D followed a U-shaped curve in RCS model, and minimum mortality was around 20% at 0.03-0.05 µg/kg/min.

CONCLUSIONS

Sepsis phenotypes differ significantly in their treatment effects of vasoactive drug dosage and time of use, indicating the need for phenotype-specific treatment strategies to improve outcomes.

Continuous versus bolus norepinephrine administration to treat hypotension after induction of general anaesthesia in low-to-moderate risk noncardiac surgery patients: a randomised trial

BACKGROUND

Hypotension after induction of general anaesthesia (postinduction hypotension) is common in patients undergoing noncardiac surgery and frequently requires treatment with vasopressors such as norepinephrine. We tested the hypothesis that giving norepinephrine continuously using a syringe infusion pump, compared with giving it as repeated manual boluses, reduces postinduction hypotension within 15 min after starting induction of general anaesthesia in low-to-moderate risk noncardiac surgery patients.

METHODS

Patients undergoing elective noncardiac surgery were randomised to either continuous norepinephrine infusion or manual bolus norepinephrine administration intravenously during induction of general anaesthesia. In both groups, norepinephrine was administered through a peripheral venous catheter. Blood pressure was measured by clinicians using intermittent oscillometry. We additionally performed blinded continuous noninvasive blood pressure monitoring to quantify the duration and extent of postinduction hypotension. The primary endpoint was postinduction hypotension, defined as the area under a MAP of 65 mm Hg within 15 min after starting induction of general anaesthesia.

RESULTS

From 276 randomised patients, 261 had complete data (median age: 62 yr; 40% female). The median (25th-75th percentile) area under a MAP of 65 mm Hg was 3.6 (0.0-16.6) mm Hg × min in patients assigned to continuous norepinephrine infusion, compared with 5.5 (0.5-24.5) mm Hg × min in patients assigned to manual bolus norepinephrine administration (P=0.070). The median duration of MAP values <65 mm Hg was 1.0 (0.0-2.5) min vs 1.4 (0.2-3.2) min (P=0.052).

CONCLUSIONS

Continuous administration of norepinephrine, compared with repeated manual bolus doses, did not reduce postinduction hypotension in low-to-moderate risk noncardiac surgery patients who had intermittent oscillometric blood pressure monitoring.

Management of cardiogenic shock: state-of-the-art

The management of cardiogenic shock is an ongoing challenge. Despite all efforts and tremendous use of resources, mortality remains high. Whilst reversing the underlying cause, restoring/maintaining organ perfusion and function are cornerstones of management. The presence of comorbidities and preexisting organ dysfunction increases management complexity, aiming to integrate the needs of vital organs in each individual patient. This review provides a comprehensive overview of contemporary literature regarding the definition and classification of cardiogenic shock, its pathophysiology, diagnosis, laboratory evaluation, and monitoring. Further, we distill the latest evidence in pharmacologic therapy and the use of mechanical circulatory support including recently published randomized-controlled trials as well as future directions of research, integrating this within an international group of authors to provide a global perspective. Finally, we explore the need for individualization, especially in the face of neutral randomized trials which may be related to a dilution of a potential benefit of an intervention (i.e., average effect) in this heterogeneous clinical syndrome, including the use of novel biomarkers, artificial intelligence, and machine learning approaches to identify specific endotypes of cardiogenic shock (i.e., subclasses with distinct underlying biological/molecular mechanisms) to support a more personalized medicine beyond the syndromic approach of cardiogenic shock.

The impact of norepinephrine dose reporting heterogeneity on mortality prediction in septic shock patients

BACKGROUND

Norepinephrine (NE) is a cornerstone drug in the management of septic shock, with its dose being used clinically as a marker of disease severity and as mortality predictor. However, variations in NE dose reporting either as salt formulations or base molecule may lead to misinterpretation of mortality risks and hinder the process of care.

METHODS

We conducted a retrospective analysis of the MIMIC-IV database to assess the impact of NE dose reporting heterogeneity on mortality prediction in a cohort of septic shock patients. NE doses were converted from the base molecule to equivalent salt doses, and their ability to predict 28-day mortality at common severity dose cut-offs was compared.

RESULTS

4086 eligible patients with septic shock were identified, with a median age of 68 [57-78] years, an admission SOFA score of 7 [6-10], and lactate at diagnosis of 3.2 [2.4-5.1] mmol/L. Median peak NE dose at day 1 was 0.24 [0.12-0.42] μg/kg/min, with a 28-day mortality of 39.3%. The NE dose showed significant heterogeneity in mortality prediction depending on which formulation was reported, with doses reported as bitartrate and tartrate presenting 65 (95% CI 79-43)% and 67 (95% CI 80-47)% lower ORs than base molecule, respectively. This divergence in prediction widened at increasing NE doses. When using a 1 μg/kg/min threshold, predicted mortality was 54 (95% CI 52-56)% and 83 (95% CI 80-87)% for tartrate formulation and base molecule, respectively.

CONCLUSIONS

Heterogeneous reporting of NE doses significantly affects mortality prediction in septic shock. Standardizing NE dose reporting as base molecule could enhance risk stratification and improve processes of care. These findings underscore the importance of consistent NE dose reporting practices in critical care settings.