Blood pressure in the finger was measured by a servo-plethysmomanometer constructed after the design of Penàz, which uses the principle of the unloaded arterial wall. The device contains a photoelectric plethysmograph mounted in an inflatable cuff and an electro-pneumatic transducer to control air pressure in the cuff via a servosystem. Comparison of simultaneous measurements of intra-arterial pressure in the brachial artery was performed on 33 patients suspected of having hypertension. In 12 patients evaluation of the technique could not be carried out due to technical failures or distorted blood pressure wave forms. Results of the remaining 21 patients show a mean underestimation of intra-arterial blood pressure by finger cuff blood pressure of 0.8 kPa (6 mm Hg), both for systolic and diastolic levels. The scatter range of the difference is from 1.9 to -3.5 kPa for systolic and 0.1 to -2.5 kPa for diastolic values. It appears that, although not all technical problems are solved, the Penàz servo-plethysmo-manometer is potentially an elegant method by which to arrive at the fully calibrated wave form of blood pressure in a finger in a non-invasive and continuous fashion.
Esophageal phonocardiography (ePCG) has the advantage that certain heart sounds are picked up near
their sites of origin, whereas in conventional surface phonocardiography (sPCG) attenuation of the vibration occurs
in the pathway to the microphone. The disadvantage of directional sensitivity of an accelerometer-type microphone
has been eliminated by constructing biaxial microphones; with the aid of an electronic axes rotation, optimal
recording of heart vibrations in the horizontal plane is achieved. ePCG has clinical value because of diagnosing
mitral valve regurgitation (MR) better than conventional PCG, especially in patients having prosthetic valves in both
mitral and aortic orifices where left ventricular angiography is not easily accomplished. Regarding the level of the
microphone in the esophagus it has been established that various significant vibration patterns can be recorded at
different heights. This variety of patterns is also explained by the distance to specific sources: heart sounds generated
in the vicinity of the microphone are better detected with respect to others having a more distant origin. In this way
the method contributes to the discussion about valvular components contained in the first heart sound. In the
investigation simultaneous recordings with M-mode echocardiogram and pulsation curves have been obtained. More
than 60 patients and normal subjects were examined. In 9 patients with prosthetic valves in both mitral and aortic
orifices and 8 patients with mitral valve prolapse, MR was proved by ePCG in respectively 4 and 2 cases while sPCG
failed to do so.
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