| 摘要 |
Venous pressures are easily and accurately measurable with a manometric device, closed at one end to substantially lessen the possibility of retrograde infection and having a sight glass affixed to a graduated ruler backing to align the zero level thereof with a patient's zero level. The reservoir of the device is comprised of a transparent plastic tube overlying a pattern imprinted along the length of the ruler, and is filled with a transparent liquid, the level of which provides the pressure indication. The transparent plastic tube by itself operates as a divergent lens to reduce the apparent size of the overlaid pattern in that portion of the tube filled by air, while the transparent tube and liquid operate as a convergent lens to increase the apparent size of the pattern beneath the liquid filled portion of the tube, thereby emphasizing the level to which the fluid surface extends.
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