Resting pressures recorded from the anal sphincter by the open-tip method seem to reflect the last pressure to which the catheter tip was exposed before it entered the sphincter, presumable because sphincter tissues "seal" the recording orifice and thereby "trap" pressure within the recording system. By injecting or infusing small increments of fluid into the system, one can measure a physiologically meaningful pressure--the pressure required to break the "seal." For the resting sphincter, this pressure has been termed the resting yield pressure; for the maximally tightened sphincter, the augmented yield pressure. By determining yield pressures before and during active contraction of the sphincter the involuntary and voluntary components of sphincter function can be separately assessed. Measurement of yield pressures can separate sphincters judged competent or incompetent on clinical grounds. Injection of microliter quantities of fluid into the recording catheter whose tip is in the sphincter causes a marked rise in pressure. Although "bleeders" or constant slow infusions of fluid do not affect pressures recorded from within a cavity, they do significantly alter pressures recorded from a sphincter zone.

Anal Canal↗

PubMed1966

The pressure inversion point: its genesis and reliability.

Explore the source record for details and available documents.

Adolescent↗

PubMed1966

The present status of esophageal manometry.

Explore the source record for details and available documents.

Esophageal Diseases↗

PubMedDate not supplied

Comparative study using computed tomographic thin-section zoom reconstructions and anatomic macrosections of the temporal lobe.

Thin-section (1.5 mm) high-spatial-resolution computed tomography (CT) in combination with computerized high-resolution image reconstruction is an effective, noninvasive means of studying patients with a variety of temporal bone abnormalities. To determine what degree of definition and anatomic accuracy could currently be obtained by using these techniques, we performed thin-section CT and high-resolution image reconstruction with use of two fresh-frozen cadaver head specimens. We then compared these images with the actual anatomic macrosections subsequently obtained from the specimens. We concluded that high-resolution CT scans of temporal bone can produce accurate, highly detailed, diagnostic images of the internal auditory canal, vestibule, cochlea, vestibular aqueduct, semicircular canals, and middle ear space.

Cadaver↗

PubMedDate not supplied

Mayo Clinic and Medical School Biodynamics Research Unit.

The facilities that make up the Mayo Biodynamics Research Unit include the dynamic spatial reconstructor (DSR), which when fully operational will generate raw data at 200 million samples per second. Processing of these data will require a computer capable of several billion arithmetic operations per second.

Biomechanical Phenomena↗

PubMedDate not supplied

Noninvasive numerical vivisection of anatomic structure and function of the intact circulatory system using high temporal resolution cylindrical scanning computerized tomography.

A high temporal resolution cylindrical scanning computerized tomographic system (DSR) is being built for study of anatomic structural/functional relationships of heart, lungs, vascular anatomy, and circulatory dynamics in any region of the body. Unlike current commercial CT scanners which scan only one or, at most, a few cross sections at a time, cylindrical scanners such as the current Mayo SSDSR and upcoming DSR scan nearly 250 cross sections simultaneously. Twenty-eight or more multiplanar images over a range of 160 or more degrees of an entire rapidly moving structure such as the heart or a segment of the circulation will be recorded in periods as short as 10 msec by the DSR at 60/sec rates and stored in computer memory. The scanned volumes can then be sectioned mathematically in any direction at will, including zooming in on regions of interest to problems at hand (e.g., clinical diagnoses). Progression from biomedical investigation to practical clinical and health care uses requires development of special-purpose, readily replicable, economical (but very high speed and volume) data handling and computational devices. The ultimates overall objective is to quantitatively characterize the performance of the human cardiopulmonary and circulatory systems utilizing pertubations associated with various types of physiologic stress and congenital or acquired disease processes including neoplasia.

Animals↗