ABSTRACT
STUDY DESIGN: Retrospective study. OBJECTIVE: To determine if there is an association between obstructive sleep apnoea (OSA) and blood pressure (BP) pattern or heart rate variability (HRV) in people with spinal cord injury (SCI). SETTING: A state-based spinal cord service in Victoria, Australia. METHODS: We identified 42 subjects who had ambulatory BP monitoring (ABPM) within 6 months of a diagnostic sleep study at Austin Hospital between 2009 and 2014. Markers for autonomic function, including circadian BP pattern and HRV were extracted from the ABPM study database. Apnoea/hypopnoea index (AHI), arousals/hour and oxygen desaturation index were extracted from the sleep study database. Subjects with a nocturnal systolic BP dipping more than 10% of daytime value were defined as dippers, between 10 and 0% were non-dippers and those with a higher night than day systolic BP were reverse dippers. Severity of OSA is classified as non-OSA (AHI < 5), mild (AHI 5-15), moderate (AHI 15-30) and severe (AHI > 30). RESULTS: Subjects (n = 42) were predominantly male (85.7%), aged 44 ± 15.4 (mean ± SD), with a BMI of 24.4 ± 5.7 (mean ± SD) and mainly tetraplegic (92.9%). There was no difference in AHI, oxygen desaturation index or arousals/hour between dippers, non-dippers and reverse dippers. None of the HRV parameters differed between dippers, non-dippers and reverse dippers. No differences were found in 24 h, night-time, daytime or nocturnal dip in BP between subjects with non-OSA, mild, moderate and severe OSA. CONCLUSION: We found no relationship between BP pattern or HRV and the severity of OSA in persons with SCI.
ABSTRACT
STUDY DESIGN: Observational study. OBJECTIVES: To quantify diurnal blood pressure (BP) patterns and nocturnal hypertension and to measure diurnal urine production in people with chronic spinal cord injury (SCI), compared with controls without SCI. SETTING: Chronic SCI population in the community in Victoria, Australia. METHODS: Participants were recruited by advertisement, and sustained SCI at least a year prior or were healthy able-bodied volunteers. Participants underwent ambulatory BP monitoring (ABPM), measurement of urine production, and completed questionnaires regarding orthostatic symptoms. Comparisons were made between participants with tetraplegia or paraplegia and able-bodied controls. Participants with night:day systolic BP < 90% were classified as dippers, 90-100% as nondippers, and >100% as reverse dippers. RESULTS: Groups with tetraplegia (n = 51) and paraplegia (n = 33) were older (42.1 ± 15 and 41.1 ± 15 vs. 32.4 ± 13 years, mean ± s.d.) and had a higher prevalence of males (88 and 85% vs. 60%) than controls (n = 52). The average BP was 110.8 ± 1.5/64.4 ± 1.2 mmHg, 119.4 ± 2.1/69.8 ± 1.5 mmHg, and 118.1 ± 1.4/69.8 ± 1.0 mmHg in tetraplegia, paraplegia, and controls, respectively. Of participants with tetraplegia, paraplegia and controls, reverse dipping was observed in 45, 13, and 2% (p < 0.001), while nocturnal hypertension was observed in 13, 23, and 18%, respectively (p = 0.48). A reduction in nocturnal urine flow rate compared with the day was observed in paraplegia and controls, but not tetraplegia. CONCLUSIONS: Similar to the effects of acute SCI, chronic SCI, specifically tetraplegia, also causes isolated nocturnal hypertension, reverse dipping, orthostatic intolerance, and nocturnal polyuria. Cardiovascular risk management and assessment of orthostatic symptoms should include ABPM.
Subject(s)
Blood Pressure , Circadian Rhythm , Spinal Cord Injuries/physiopathology , Urination , Adolescent , Adult , Aged , Blood Pressure/physiology , Blood Pressure Monitoring, Ambulatory , Chronic Disease , Circadian Rhythm/physiology , Female , Heart Rate/physiology , Humans , Hypertension/etiology , Hypertension/physiopathology , Male , Middle Aged , Paraplegia/etiology , Paraplegia/physiopathology , Posture/physiology , Prospective Studies , Quadriplegia/etiology , Quadriplegia/physiopathology , Spinal Cord Injuries/complications , Urination/physiology , Young AdultABSTRACT
BACKGROUND: Although management of hypertension is a daily activity of primary care practitioners, it remains one of the most demanding areas of medicine. Reasons for this include the imprecision of blood pressure measurement, the complexity of assessing cardiovascular risk, and the need to use multiple agents to control blood pressure. OBJECTIVE: This article discusses clinical scenarios that force clinicians to make decisions about blood pressure measurement techniques and methods of treatment. DISCUSSION: We consider ambulatory compared to office based blood pressure measurement, the types of clinical scenarios in which ambulatory blood pressure monitoring is likely to be beneficial, what to consider when there is nocturnal elevated blood pressure, and the assessment and management of resistant hypertension.
