Dipping status may be determined by nocturnal urination

Area of Science:

• Cardiology
• Hypertension Research
• Sleep Medicine

Background:

• Nondipping blood pressure, defined as less than a 10% reduction in blood pressure overnight, is a significant prognostic indicator identified through 24-hour ambulatory blood pressure monitoring.
• Nocturnal blood pressure patterns can be influenced by physiological events such as nocturia (waking to urinate).
• Standard 24-hour ambulatory blood pressure monitoring calculations may include awake periods during the night, potentially misrepresenting the true nocturnal blood pressure dip.

Purpose of the Study:

• To investigate the impact of nocturia on the accuracy of 24-hour ambulatory blood pressure monitoring.
• To compare blood pressure dipping patterns using standard daytime/nighttime averages versus patient-reported awake/asleep periods.
• To determine if accounting for actual sleep patterns improves the classification of blood pressure dipping status.

Main Methods:

• Retrospective analysis of 97 subjects with reported nocturia undergoing 24-hour ambulatory blood pressure monitoring.
• Comparison of two calculation methods: 1) total daytime vs. total nighttime means, and 2) actual daytime awake vs. nighttime asleep means.
• Statistical analysis to evaluate differences in nocturnal blood pressure decline and prevalence of nondipping between the two methods.

Main Results:

• The method using actual awake/asleep periods showed a significantly greater nocturnal blood pressure decline (systolic: 17.1 mmHg, diastolic: 13.8 mmHg) compared to the total day/night method (systolic: 14.4 mmHg, diastolic: 11.8 mmHg).
• The prevalence of systolic nondipping decreased from 42.2% to 31.9%, and diastolic nondipping decreased from 22.6% to 11.3% when using the actual sleep pattern method.
• The percentage of systolic blood pressure dipping increased from 10.1% to 12.0%, and diastolic dipping from 14.2% to 16.7% with the adjusted method.

Conclusions:

• Including awake blood pressure readings during nighttime hours can obscure the true nocturnal blood pressure dipping pattern in individuals experiencing nocturia.
• Adjusting 24-hour ambulatory blood pressure monitoring analysis to reflect actual patient sleep and wake times enhances the accuracy of blood pressure dipping assessment.
• This refined approach provides a more precise evaluation of cardiovascular risk associated with blood pressure regulation during sleep.