Stress from obstructive sleep apnoea (OSA) stimulates catecholamine release consequently exacerbating hypertension. However, different studies have shown a conflicting impact of continuous positive airway pressure (CPAP) treatment in patients with OSA on catecholamine levels and blood pressure. We aimed to examine changes to catecholamine levels and blood pressure in response to CPAP treatment. We conducted a meta-analysis of data published up to May 2020. The quality of the studies was evaluated using standard tools for assessing the risk of bias. Meta-analysis was conducted using RevMan (v5.3) and expressed in standardised mean difference (SMD) for catecholamines and mean difference (MD) for systolic (SBP) and diastolic blood pressure (DBP). A total of 38 studies met our search criteria; they consisted of 14 randomised control trials (RCT) totalling 576 participants and 24 prospective cohort studies (PCS) of 547 participants. Mean age ranged between 41 and 62yr and body mass index between 27.2 and 35.1kg/m2. CPAP treatment reduced 24-hour urinary noradrenaline levels both in RCT (SMD = -1.1; 95% confidence interval (CI): -1.63 to -0.56) and in PCS (SMD = 0.38 (CI: 0.24 to 0.53). SBP was also reduced by CPAP treatment in RCT (4.8mmHg; CI: 2.0-7.7) and in PCS (7.5mmHg; CI: 3.3-11.7). DBP was similarly reduced (3.0mmHg; CI: 1.4-4.6) and in PCS (5.1mmHg; CI: 2.3-8.0). In conclusion, CPAP treatment in patients with OSA reduces catecholamines levels and blood pressure. This suggests that sympathetic activity plays an intermediary role in hypertension associated with OSA-related stress.
- sympathetic activity