Background:
External counterpulsation (ECP) is a noninvasive method used to augment cerebral perfusion but the optimal use of ECP in ischemic stroke has not been well documented. We aim to investigate the effects of increasing ECP treatment pressure on cerebral blood flow and blood pressure (BP).
Methods:
We recruited 38 acute ischemic stroke patients with large artery occlusive disease and 20 healthy elderly. Mean cerebral blood flow velocities (CBFV) of bilateral middle cerebral artery were monitored using transcranial dopper. Continuous beat-to-beat BP was measured via finger cuffs. We started ECP treatment pressure from 150mmHg, then gradually increased to 187.5mmHg, 225mmHg and 262.5mmHg. CBFV and BP were recorded before ECP and during each pressure increment respectively for 3 minutes. CBFV data of patients was analyzed based on whether it was ipsilateral or contralateral to the infarct.
Results:
Median NIHSS of stroke patients was 5.5 and mean time after stroke onset was 5.24 days. Mean BP was significantly elevated from baseline in both groups after ECP started. BP increase percentages of two groups similarly kept augmented following raised ECP pressure and reach maximium at 262.5mmHg (patients 16.9% vs. controls 16.52% compared with baseline). Under different ECP pressures, ipsilateral mean CBFV of stroke patients increased 5.15% (150mmHg), 4.35% (187.5mmHg), 4.55% (225mmHg) and 3.52% (262.5mmHg) from baseline. All were significantly higher than baseline but did not differ among different pressures. Contralateral mean CBFV changed likewise (5.16%, 4.02%, 3.7% and 3.34% increase from baseline). Mean CBFV of controls under ECP pressures did not increase from baseline.
Conclusion:
The increasing treatment pressure of external counterpulsation continuously augments blood pressure but not cerebral blood flow velocity of ischemic stroke patients with large artery occlusive disease. Cerebral blood flow velocity of stroke patients significantly increases from baseline under ECP pressure of 150mmHg but it reaches a plateau as ECP pressure further raises. Among 4 ECP pressures above, 150mmHg is the optimal treatment pressure for ischemic stroke due to higher risks of hypertension-related complications in acute stroke with higher ECP pressure.