Multi-channel electrical bioimpedance: a non-invasive method to simultaneously measure cardiac output and individual arterial limb flow in patients with cardiovascular disease.

BACKGROUND: Cardiac output is the fundamental determinant of peripheral blood flow however; optimal regional tissue perfusion is ultimately dependant on the integrity of the arterial conduits that transport flow. A complete understanding of tissue perfusion requires knowledge of both cardiac and peripheral blood flow. Existing noninvasive devices do not simultaneously assess the cardiac and peripheral circulations. Multi-channel electrical bioimpedance (MEB) measures cardiac output and peripheral flow simultaneously. OBJECTIVES: Assessment of the accuracy of MEB to measure cardiac output in patients with clinical heart failure (group 1) and to measure regional arterial limb flow in patients with exertional leg pain clinically thought to have peripheral arterial disease (group 2). METHODS: Cardiac output was measured by MEB in 44 patients with moderate to severe clinical heart failure (group 1) and was compared to a cardiac output measured by 2D-Echo Doppler. Peripheral blood flow (regional ankle and arm flow) was measured by MEB in another group of 25 patients with exertional leg pain clinically thought to be claudication (group 2). The MEB ankle/arm flow ratio (AAI index) was then compared to a conventional ankle/brachial pressure ratio (ABI index). RESULTS: There was excellent correlation between the mean cardiac index by MEB (2.01 l/min/m(2)) and by 2D-Echo Doppler (2.06 l/min/m(2)) and bias and precision was 0.05 (2.4%) and +/-0.48 l/min/m(2) (+/-23%), respectively. The correlation was maintained for each measurement over a wide range of cardiac indices. There was good correlation between AAI and ABI measurements (P < 0.05). CONCLUSIONS: MEB accurately measures cardiac output in patients with moderate to severe clinical heart failure and accurately measures regional arterial limb flow in patients with peripheral arterial disease.

Multi-channel electrical bioimpedance: a new noninvasive method to simultaneously measure cardiac and peripheral blood flow.

OBJECTIVES: We sought to assess the ability of a new multi-channel electrical bioimpedance (MEB) methodology to accurately measure both cardiac blood flow and peripheral limb blood flow. BACKGROUND: Cardiac output is the primary determinant of peripheral blood flow; however, optimal regional tissue perfusion is ultimately dependent on the patency of the arterial conduits that transport that flow. A complete understanding of regional tissue perfusion requires knowledge of both cardiac and peripheral blood flow. Existing noninvasive devices do not simultaneously assess the cardiac and peripheral circulations. METHODS: Cardiac blood flow (cardiac output) was measured by MEB in 30 healthy volunteers and was compared to a 2D-Echo Doppler cardiac output. Peripheral blood flow (regional ankle and arm flow) was measured by MEB in 15 healthy volunteers. The MEB ankle/arm flow ratio (AAI index) was then compared to a conventional ankle/brachial pressure ratio (ABI index). RESULTS: There was good correlation between the mean cardiac index by MEB (3.08 l/min/m2) and by Echo Doppler (3.13 l/min/m2) and bias and precision was 0.051 (1.6%) and +/-0.52 l/min/m2 (+/-17%), respectively. The close correlation was maintained for each measurement over a wide range of cardiac indices. There was good correlation between AAI and ABI measurements (p < 0.05) with a sensitivity of 100% and specificity of 100%. CONCLUSIONS: MEB methodology can precisely measure cardiac output and peripheral limb flow in healthy volunteers.

Measurement of atmospheric neutrino flux consistent with tau neutrino appearance.

A search for the appearance of tau neutrinos from nu(mu) <--> nu(tau) oscillations in the atmospheric neutrinos has been performed using 1489.2 days of atmospheric neutrino data from the Super-Kamiokande-I experiment. A best fit tau neutrino appearance signal of 138+/-48(stat)-32(+15)(syst) events is obtained with an expectation of 78+/-26(syst). The hypothesis of no tau neutrino appearance is disfavored by 2.4 sigma.

Search for supernova relic neutrinos at Super-Kamiokande.

A search for the relic neutrinos from all past core-collapse supernovae was conducted using 1496 days of data from the Super-Kamiokande detector. This analysis looked for electron-type antineutrinos that had produced a positron with an energy greater than 18 MeV. In the absence of a signal, 90% C.L. upper limits on the total flux were set for several theoretical models; these limits ranged from 20 to 130 macro nu(e) cm(-2) s(-1). Additionally, an upper bound of 1.2 macro nu(e) cm(-2) s(-1) was set for the supernova relic neutrino flux in the energy region E(nu)>19.3 MeV.

Limits on the neutrino magnetic moment using 1496 days of Super-Kamiokande-I solar neutrino data.

A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)

Evidence for an oscillatory signature in atmospheric neutrino oscillations.

Muon neutrino disappearance probability as a function of neutrino flight length L over neutrino energy E was studied. A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed L/E distribution constrained nu(micro)<-->nu(tau) neutrino oscillation parameters; 1.9x10(-3)0.90 at 90% confidence level.

Search for nu(e) from the sun at Super-Kamiokande-I.

We present the results of a search for low energy nu(e) from the Sun using 1496 days of data from Super-Kamiokande-I. We observe no significant excess of events and set an upper limit for the conversion probability to nu(e) of the 8B solar neutrino. This conversion limit is 0.8% (90% C.L.) of the standard solar model's neutrino flux for total energy=8-20 MeV. We also set a flux limit for monochromatic nu(e) for E(nu(e))=10-17 MeV.