Arrival blood pressure in hypertensive and non-hypertensive spontaneous intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Hypertension is a known risk factor for intracerebral hemorrhage (ICH), but it is unclear whether blood pressure (BP) at hospital arrival can be used to distinguish hypertensive ICH from non-hypertensive etiologies. PATIENTS AND METHODS: We performed a single-center cohort study using data from consecutive ICH patients over 12 months. ICH characteristics including etiology were prospectively adjudicated by two attending neurologists. Using adjusted linear regression models, we compared first recorded systolic BPs (SBP) and mean arterial pressures (MAP) in patients with hypertensive vs. other ICH etiologies. We then used area under the ROC curve (AUC) analysis to determine the accuracy of admission BP in differentiating between hypertensive and non-hypertensive ICH. RESULTS: Of 311 patients in our cohort (mean age 70.6 ± 15.6, 50% male, 83% white), the most frequent ICH etiologies were hypertension (50%) and cerebral amyloid angiopathy (CAA; 22%). Mean SBP and MAP for patients with hypertensive ICH was 175.1 ± 32.9 mmHg and 120.4 ± 22.9 mmHg, respectively, compared to 156.4 ± 28.0 mmHg and 109.6 ± 20.3 mmHg in non-hypertensive ICH (p < .001). Adjusted models showed that hypertensive ICH patients had higher BPs than those with CAA (mean SBP difference 10.7 mmHg [95% CI 0.8-20.5]; mean MAP difference 8.1 mmHg [1.1-15.0]) and especially patients with other non-CAA causes (mean SBP difference 23.9 mmHg [15.3-32.4]; mean MAP difference 14.5 mmHg [8.5-20.6]). However, on a patient-level, arrival BP did not reliably discriminate between hypertensive and non-hypertensive etiologies (AUC 0.660 [0.599-0.720]). CONCLUSIONS: Arrival BP differs between hypertensive and non-hypertensive ICH but should not be used as a primary determinant of etiology, as hypertension may be implicated in various subtypes of ICH.

The role of inertial cavitation in acoustic droplet vaporization.

The vaporization of a superheated droplet emulsion into gas bubbles using ultrasound--termed acoustic droplet vaporization (ADV)--has potential therapeutic applications in embolotherapy and drug delivery. The optimization of ADV for therapeutic applications can be enhanced by understanding the physical mechanisms underlying ADV, which are currently not clearly elucidated. Acoustic cavitation is one possible mechanism. This paper investigates the relationship between ADV and inertial cavitation (IC) thresholds (measured as peak rarefactional pressures) by studying parameters that are known to influence the IC threshold. These parameters include bulk fluid properties such as gas saturation, temperature, viscosity, and surface tension; droplet parameters such as degree of superheat, surfactant type, and size; and acoustic properties such as pulse repetition frequency and pulse width. In all cases the ADV threshold occurred at a lower rarefactional pressure than the IC threshold, indicating that the phase transition occurs before IC events. The viscosity and temperature of the bulk fluid are shown to influence both thresholds directly and inversely, respectively. An inverse trend is observed between threshold and diameter for droplets in the 1 to 2.5 microm range. Based on a choice of experimental parameters, it is possible to achieve ADV with or without IC.