医疗城 · 设备实验室 · 第 47 台，共 69 台
胎儿监护仪
Fetal Monitor
BMEssentia 医疗城设备实验室中的胎儿监护仪。以可交互 3D 打开设备，逐个部件拆解，了解其工作原理，然后在 BMEssentia 平台上系统学习，并向 Essentia 提问。
本页的设备实验室内容为英文，与医疗城中的内容一致。
- 10 个部件
- 设备实验室中有 2 种配置
- 又称: Ctg, Cardiotocograph
设备实验室
Fetal Monitor
Two transducers held on the abdomen by elastic belts. One transmits continuous-wave ultrasound and listens for the Doppler shift from moving fetal cardiac structures; the rate is the lag at which an autocorrelation of that envelope peaks. The other is a strain gauge on a guard ring reading the tension in its own belt, and its axis is unitless because nothing it measures is a pressure.
配置
设备实验室中的各个版本。
External, Doppler ultrasound and tocodynamometer
Two transducers held on the abdomen by elastic belts. One transmits continuous-wave ultrasound and listens for the Doppler shift from moving fetal cardiac structures; the rate is the lag at which an autocorrelation of that envelope peaks. The other is a strain gauge on a guard ring reading the tension in its own belt, and its axis is unitless because nothing it measures is a pressure.
Internal, fetal scalp electrode and intrauterine pressure catheter
A spiral electrode turned into the fetal scalp against a maternal reference plate, giving a genuine fetal electrocardiogram from which the interval between one R wave and the next is timed directly; and a fluid-filled catheter in the amniotic cavity against an external strain gauge zeroed to atmosphere, giving a pressure in millimetres of mercury with a true zero.
工作原理
在设备实验室中探索。
Where the rate quantum comes from
Hold everything else still and change only the sample interval the lag search runs on, then watch the reported rate and the spacing of the values it can take.
Which peak the correlator took
Change only the size of the second mechanical event in the envelope, and watch the correlogram rather than the number.
Whose heart is on the upper trace
Move the transducer towards the maternal midline and watch three things at once: the reported rate, the maternal rate, and the quality indicator.
What the lower trace is really measuring
Change the belt tension and the abdominal wall thickness one at a time, with nothing about the contraction changing, and watch the amplitude and the timing separately.
What a zero and a unit buy
On the internal configuration, move the height of the pressure transducer against the catheter tip, then separately damp the catheter, and watch the resting tone and the Montevideo total.
What the paper speed does to the same recording
Change only the paper speed and look at the chart, not at the numbers.
部件
逐个部件讲解。
Enclosure, trolley and cable management
A squat moulded box about a third of a metre across, standing on a small wheeled trolley at the head of a couch. A carrying handle is recessed into the top, vent slots run down both flanks, a shelf under it holds a box of chart paper, and two round holsters on the side hold the transducers when they are not on anybody.
Keyed transducer sockets and the front panel
Four round sockets in a row along the lower front panel, each inside a coloured ring and each with a printed legend under it: blue for the ultrasound transducer, pink for the toco, yellow for the fetal electrode and grey for the pressure line. Each one has a keyway cut into the shell.
Numeric and waveform display
A landscape panel filling the upper left of the front, showing two bands with time running left to right, a column of large numerics down the right, and a bar for signal quality along the bottom. The fetal rate is the biggest number on the machine and the maternal rate sits directly beneath it.
Thermal chart recorder and paper path
A door across the lower front with a latch, a tear bar above it, and a strip of ruled paper emerging from a slot and hanging down. Behind the door are a thermal print head the full width of the paper, a rubber platen roller and a drive.
Paper speed selector, 1 to 3 cm per minute
A small knurled rotary control on the lower left of the panel with three detents and three printed numbers beside it: one, two and three. Below them, in small type, the units, centimetres per minute.
Maternal heart rate channel
A small sensor clipped to a fingertip with a short cable back to the panel, and a second numeric on the screen directly under the fetal one. On the internal configuration the same number can be derived from the maternal complex the scalp electrode already sees.
Signal quality index and loss of contact
A bar of five segments on the front panel beside the sockets, green when the signal is good and amber or red when it is not, with a printed legend under it. On this build a separate bench panel on top of the enclosure shows what the bar is derived from, which no real monitor does.
Maternal event marker handset
A short moulded handset on a coiled cable, with a single large button, lying on the couch beside her hand. She presses it when she feels something.
Rate limits, signal-loss alarm and annunciation
A translucent strip across the top edge of the enclosure with three emitters behind it, an amber silence key on the right of the panel and two keys that move the rate limits. The strip flashes red at high priority and holds a steady colour at anything lower.
Audio channel, Doppler sound and volume
A grille on the flank with a cone behind it and a knurled volume knob on the front panel. On the external configuration it carries the returning Doppler signal itself; on the internal one it carries a synthesised tone per beat.