Learn More
We compared two methods of assessment of baroreflex sensitivity in eight supine healthy volunteers during repeated baseline measurements and various conditions of cardiac autonomic blockade. The spontaneous baroreflex method involved computer scanning of recordings of continuous finger arterial pressure and electrocardiogram to locate sequences of three or(More)
Heart rate variability is a recognized parameter for assessing autonomous nervous system activity. Fourier transform, the most commonly used method to analyze variability, does not offer an easy assessment of its dynamics because of limitations inherent in its stationary hypothesis. Conversely, wavelet transform allows analysis of nonstationary signals. We(More)
This study compared spontaneous baroreflex sensitivity (BRS) estimates obtained from an identical set of data by 11 European centers using different methods and procedures. Noninvasive blood pressure (BP) and ECG recordings were obtained in 21 subjects, including 2 subjects with established baroreflex failure. Twenty-one estimates of BRS were obtained by(More)
How the autonomic nervous system influences the fractal dynamics of heart rate (HR) and blood pressure (BP) remains unclear. The purpose of our study was to separately assess cardiac vagal and sympathetic (cardiac vs. vascular) influences on fractal properties of HR and BP as described by scale exponents of detrended fluctuation analysis (DFA). R-R(More)
It is unclear whether the complexity of the variability of the systolic arterial pressure (SAP) provides complementary information to that of the heart period (HP). The complexity of HP and SAP variabilities was assessed from short beat-to-beat recordings (i.e., 256 cardiac beats). The evaluation was made during a pharmacological protocol that induced vagal(More)
In the critical care setting, α-2 agonists present a multifaceted profile: sedation combined with arousability, suppression of delirium, preservation of respiratory drive, reduced O(2) consumption, preserved renal function, and reduced protein metabolism. In addition, this review details the reduced arterial impedance, improved left ventricular performance,(More)
OBJECTIVE During septic shock, vasopressors are a cornerstone of therapy. In septic shock, very high doses of vasopressors sometimes have to be used due to vascular desensitization, the mechanisms of which are poorly understood. This study assesses whether α-2 agonists increase pressor responsiveness following lipopolysaccharide administration. DESIGN(More)
Extracellular recordings were made in the right nucleus ambiguus of urethane-anesthetized rats from 33 neurons that were activated at constant latency from the craniovagal cardiac branch. Their calculated conduction velocities were in the B-fiber range (1.6-13.8 m/s, median 4.2), and most (22/33) were silent. Active units were confirmed as cardiac vagal(More)
Beat-by-beat variations in blood pressure and RR-interval are interrelated by the actions of baroreflex and non-baroreflex responses. This study had two purposes: (1) to examine the spontaneous relationships between RR-interval and systolic blood pressure to determine the relative occurrence of baroreflex and non-baroreflex responses in humans, and (2) to(More)
The effects of clonidine, a centrally acting alpha 2-adrenergic receptor agonist, on depth of fentanyl anesthesia and on cardiovascular response to laryngoscopy and intubation were studied. Twenty-four patients undergoing aortocoronary bypass surgery (ACBS) with a history of arterial hypertension, coronary artery disease (NYHA class 3-4), and well-preserved(More)