Run the advanced-haemodynamics module.

Before you start

• Use an up-to-date browser on a reasonably capable phone, tablet or laptop; the surface draws live pressure traces and reads the device core continuously.
• Where possible, present on a wide screen — the arterial, CVP and PA traces and the numeric column are easiest to read together.
• The module is deliberately inactive until you open its section on the Advanced tab. A fresh session shows the standard monitor, with the familiar arterial line as its only invasive channel.

Engage haemodynamics

• On the controller, open the Advanced tab. It holds two collapsed sections, Advanced haemodynamics and Blood gas; tap Advanced haemodynamics to open it. Its header reads not engaged until you do, then shows the lines placed and the mode; the panel inside is headed Invasive pressures.
• Opening the section engages the module with a coherent default picture — there is no separate Enable button (the section is the switch; opening the tab alone changes nothing, so a blood gas can be set up without touching the lines). Nothing shows on the learner monitor until a line is both sited here and displayed there (the two-layer rule below).
• Applying any teaching preset also engages the module, with that preset's picture.
• The current controller has no separate off switch; ending or starting a new session clears the module and returns the room to the standard monitor.

Placing lines (the room layer)

Which invasive lines the scenario has sited is the instructor (room) layer. In the Advanced tab, under Line placement:

• Arterial line — Off / Attached. The arterial channel is the familiar one; attaching it shows the arterial trace and unlocks a cardiac output, index and stroke volume read from the arterial line — the one authored cardiac output shown under the pulse-contour label, tagged (PC), not a value NAP computes from the waveform — so a room without a PA catheter can still teach flow.
• Central venous (CVP) — Off / Sited.
• PA catheter (PAP + wedge) — Off / Sited. Siting the PA catheter is what makes the PA trace, the wedge, and the thermodilution cardiac output available.

Cardiac output is method-labelled: with a PA catheter it reads the thermodilution figure; from the arterial line alone it reads the pulse-contour estimate (PC) — the same one patient shown from a different line. NAP labels which method you are reading and never invents a difference between them; the pulse-contour value is a trend, not a calibrated measurement. Applying a preset sites the lines it needs; the arterial toggle stays as you set it.

Enabling displays and the two-layer rule

• Placing a line is the room layer; enabling its display is a learner control on the monitor. Open the monitor's display-settings gear and turn on the CVP or PA channel.
• The picture is resolved in two layers: a channel shows a trace only when a line is both sited (instructor) and displayed (learner).
• Enabling a display for a channel the instructor has not sited shows NO TRANSDUCER — never an invented trace. This is deliberate: the display never fabricates data.
• The new CVP and PA channels are off by default, so a plain monitor never sprouts empty invasive lanes; the arterial channel keeps its familiar attach-to-show behaviour.

Zeroing, levelling and fast-flush

These are learner device operations on the monitor, in the vitals column beside each channel.

1. Zero to atmosphere. Press Zero to reference the transducer against room air, as at the bedside.
2. Level the transducer. Raise or lower the transducer height relative to the phlebostatic axis; a mis-levelled transducer shifts the displayed pressure by the hydrostatic offset (about ±20 cm range), a common and teachable setup error.
3. Fast-flush. Press Flush to deliver a fast-flush; use it to demonstrate a square-wave test and the line's dynamic response.

The wedge press-and-hold

1. With the PA catheter sited and its display on, press and hold Wedge (hold) on the monitor. While held, the balloon inflates, the button reads WEDGED — hold to inflate, and the PA trace collapses to the lower-amplitude wedge (PAOP) tracing.
2. Read the value and release. Releasing — or the monitor losing focus — deflates immediately.

Linked and manual modes

• Linked The default, coherent teaching mode: the primitive targets plus the shared patient's BP and heart rate drive MAP, mPAP, CI, SV, SVR and PVR together.
• Manual Intentionally decouples every number so you can build a deliberate teaching contradiction. The controller shows an unmistakable MANUAL banner while it is on, and a demonstration viewer's screen carries a MANUAL badge; the learner monitor itself shows no badge, so say it out loud.

Presets

One tap sets a coherent whole patient — the invasive targets and the lines it needs, plus a matching sinus rhythm, HR, BP, SpO₂, RR and EtCO₂ (see below); your line faults, respiratory modifier and mode are left as you set them. The controller offers:

• Normal A coherent baseline set.
• Cardiogenic High wedge, low CO / CI, high SVR.
• Septic High CO, low SVR, high SvO₂.
• Hypovolaemia Low filling pressures, high SVR, low CO.
• Massive PE / RV High CVP, wedge well below PA pressure, very high PVR.
• Tamponade Blunted CVP y-descent, diastolic equalisation and pulsus paradoxus.
• Pulmonary HTN Chronically high PA pressure with a normal wedge.

A preset activates a coherent whole patient in one tap: the invasive primitives together with the matching rhythm, heart rate, blood pressure, SpO₂, respiratory rate and capnography — so a septic picture never sits beside a normal heart rate. In linked mode the derived numbers recompute from those primitives and that patient. Presets and target changes ramp over the transition time you choose, or jump straight there on Instant. Nothing moves on its own afterwards: the patient stays exactly where you put it until you change it.

Line faults and respiration

Under Line faults & respiratory coupling, per channel (arterial, CVP, PA):

• Dynamic response — the first button group on each line's row. Normal, Overdamped or Underdamped. A non-normal response distorts the trace and the numbers read from it. The monitor shows no badge for it — unlike NO TRANSDUCER and TRANSDUCER DISCONNECTED, which announce themselves, a damped line looks like a plausible trace. Recognising it from the waveform is the point of the exercise.
• Condition — the second group on the row. Good, Air bubble, Kinked or Disconnected. A disconnected line flattens its waveform to atmospheric while the true patient pressure is unchanged.
• Respiratory variation Spontaneous or Positive pressure — a bounded, visible swing on the venous and pulmonary traces to teach the effect. It is a waveform modifier, not a ventilator model. The ordinary swing moves the whole trace up and down by a set amount; the pronounced narrowing of the pulse appears on the arterial and pulmonary traces under the tamponade picture — where it falls on inspiration, the pulsus paradoxus — or under positive-pressure ventilation, where the swing reverses with the breath. In both it is scaled to each channel's own pulse pressure rather than to a fixed number of millimetres.

Reading the CVP trace

The venous trace carries teaching the numbers alone cannot:

• In complete heart block, watch the CVP beside the ECG. The atria march on their own clock, and the CVP reads the same beat timeline the ECG's P waves come from — so when an atrial beat falls in the quarter-second after an R wave, while the ventricle is contracting, the trace shows an accentuated a-wave on that beat: the cannon a-wave picture, lined up with the rhythm above it. Point at the P wave, then at the wave it made. The same dissociation in ventricular tachycardia does the same thing.

That alignment is a consequence of how the module is built rather than a picture drawn for the occasion: the timing comes from the same cardiac events the rest of the monitor is drawn from. The magnitudes are teaching values — NAP makes no claim to validated waveform fidelity.

The lines during CPR

An arrest suppresses the patient's own blood pressure, so the invasive numbers go blank — that is the picture of a pulseless patient, not a broken line. Start compressions and the arterial trace and numeric come back as the compression-generated pressure, which rises and falls with the compression quality you set, and blanks again the moment compressions stop.

• CPP — with an arterial line and a central line both in place, a coronary-perfusion-pressure tile appears alongside the other numbers. It is a difference between two pressures, so it needs both lines; with only one there is no tile at all — it is a difference, and a difference needs two numbers.
• It marks the level historically associated with return of circulation, and reads it as a target rather than a verdict — the tile changes weight, colour and gains a dot when compressions reach it, and stays plain when they do not. Nothing turns red: poor compressions are something to improve, not an alarm.
• Good compressions sit comfortably above the level and poor ones well below, which makes it a direct way to show a class why compression quality is the intervention — the number moves when the quality does, and only then.

Changing quality mid-arrest. On the Therapy tab, beside Good/Poor, a Quality change speed decides how a Good↔Poor switch lands: Instant, 1 s or 3 s. Pick a ramp rather than Instant and the pressures sweep to their new level instead of jumping — the arterial trace, the CVP and PA compression pulses, and the CPP tile all move together, because they are all reading the one compression-quality value you changed.

EtCO₂ deliberately arrives late. When the arterial trace has finished moving, the EtCO₂ number and the capnogram plateau are still travelling, and they keep going for roughly another twenty seconds. This is the intended behaviour, not a stuck reading. At the bedside the arterial line answers a change in compression quality within one to three compressions, while EtCO₂ has to re-equilibrate a whole body's worth of CO₂ through the lungs — so it confirms the change rather than announcing it. That gap is the capnography teaching point: improve the compressions, the pressure answers now, EtCO₂ agrees a few seconds later. NAP runs that catch-up faster than a real patient would, on purpose, so the ordering is visible without holding up the scenario. Choose Instant and both step together, for when you simply want the state set.

The lag is a delay on your change and nothing else. As everywhere else in NAP, none of this evolves on its own: the compression quality is yours to set, EtCO₂ settles exactly on the value your setting implies and then stops, and the patient never drifts toward or away from a return of circulation by itself.

Presenters and observers

• A presenter switches a monitor to the haemodynamics surface to show the class; the same tab consumes one monitor slot, so switching surface does not open a second connection.
• Read-only observers follow the presented surface — they see the same traces and numbers, including a live preset change and a wedge inflated on the presenter, reproduced rather than re-simulated.
• Room-shared patient state (mode, targets, placement, line faults, respiration) is the same for everyone. Device-local view preferences (display on/off, zero, level, scale) belong to each monitor and can differ without changing the patient.

Troubleshooting

The module seems inactive

Open the controller's Advanced tab, then open its Advanced haemodynamics section — opening the section engages the module with a coherent default (the header stops reading not engaged); applying a preset also does. Opening the tab alone does nothing, and there is no separate Enable button. Remember the two-layer rule: a lane stays blank until the line is sited here and the learner has enabled that channel's display on the monitor.

A channel shows NO TRANSDUCER

The learner enabled the display but the instructor has not sited that line. Site it in the Advanced tab, and the same lane flips to a live trace.

A pressure reads higher or lower than expected

Check the transducer level and zero on the monitor — a mis-levelled transducer shifts the number by the hydrostatic offset. Also check for a line fault (damped or disconnected) staged on the controller.

The wedge will not stay inflated

That is by design: it warns at about 10 s and hard auto-deflates at about 15 s. Read the value quickly; a fresh press re-inflates.

PAP shows a single mean, not sys / dia

A non-perfusing rhythm has no PA pulse, so the trace flattens and the numeric collapses to the mean beside it — the same way CVP always shows one mean.

The presenter and an observer differ

View preferences (display on/off, zero, level, scale) are device-local, so they can differ without being a fault; the shared patient state is the same for both.

Limits

• The module is educational simulation, not clinically validated and not equivalent to any real monitor.
• It is not a diagnostic or treatment device, and not a substitute for bedside measurement.
• Cardiac output is an instructor-set primitive, not a computed one; the thermodilution and pulse-contour (PC) readouts both surface that same authored value, labelled by method — neither is a real thermodilution or continuous-cardiac-output computation.
• Invasive intracranial, ventilator and anaesthetic-machine models are out of scope.
• In a paediatric room the module rescales the numbers: body-surface area comes from the selected band's representative patient, cardiac output is class-scaled, and CI is derived from CO ÷ BSA, so the same preset pictures run at class-scaled targets. These paediatric values are plausible teaching numbers, not a validated paediatric-haemodynamics claim; the pressure-waveform shapes are the same adult-pattern generators at paediatric targets.