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The search for optimal nocturnal diurnal heart rate Index targets in ICU patients: a retrospective observational
Lan Gao1,2, QinDong Shi1,2, XiaoYu Zhang1,2
1Department of Critical Care Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
Insights
Maintaining the nocturnal diurnal heart rate index (NDHRI) within 40.0%-45.0% is linked to reduced mortality in ICU patients. This finding highlights the importance of monitoring circadian heart rate variations in critical care settings.
Area of Science:
- Critical Care Medicine
- Cardiovascular Physiology
- Chronobiology
Background:
- Circadian rhythms significantly influence cardiovascular health.
- The nocturnal diurnal heart rate index (NDHRI) reflects circadian variations in heart rate.
- Optimal NDHRI targets for Intensive Care Unit (ICU) patients are currently undefined.
Purpose of the Study:
- To establish an evidence-based NDHRI target range for ICU patients.
- To assess the association between NDHRI and mortality in critically ill patients.
Main Methods:
- Analysis of data from the eICU Collaborative Research Database (n=32,412).
- Calculation of NDHRI by dividing cumulative nighttime heart rate area by daytime area.
- Generalized additive models (GAMs) used to explore the non-linear relationship between mean NDHRI and mortality, with adjustments for confounders.
Main Results:
- A U-shaped association was observed between hospital mortality and mean NDHRI (P < 0.001).
- The optimal NDHRI range of 40.0%-45.0% was associated with the lowest mortality rates.
- Longer duration within the optimal NDHRI range correlated inversely with mortality (P < 0.001).
Conclusions:
- Maintaining NDHRI within the 40.0%-45.0% range is associated with lower mortality in critically ill patients.
- Monitoring circadian heart rate variations, using NDHRI, may be beneficial in the ICU.
- Further research and RCTs are needed to confirm causality and validate this NDHRI target range.
Background:
Circadian rhythms play a crucial role in cardiovascular health, with the nocturnal diurnal heart rate index (NDHRI) reflecting significant circadian variations. However, the optimal NDHRI target in Intensive Care Unit (ICU) patients remains undefined. This study aims to establish an evidence-based NDHRI target range and assess its association with mortality.
Methods:
Data from the eICU Collaborative Research Database (n = 32,412) were analyzed. NDHRI was calculated by dividing cumulative nighttime heart rate area by daytime area. Generalized additive models (GAMs) explored the non-linear relationship between mean NDHRI and mortality, adjusting for confounders. Subgroup analyses were conducted based on ethnicity, ICU type, and comorbidities.
Results:
A U-shaped association was observed between hospital mortality and mean NDHRI (P < 0.001). The optimal NDHRI range (40.0%-45.0%) demonstrated the lowest mortality rates. The duration spent within this range correlated inversely with mortality (P < 0.001). Subgroup analyses consistently supported these findings across diverse patient profiles.
Conclusions:
Our findings suggest an association between maintaining NDHRI within the 40.0%-45.0% range and lower mortality rates in critically ill patients, highlighting the potential utility of monitoring circadian heart rate variations in the ICU. Further research and future randomized controlled trials are essential to confirm causality and should consider this NDHRI range as a pivotal reference target.
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