Home ventilation (domiciliary NIV / cough assist)

A patient already on long-term ventilatory support arrives acutely unwell. Their baseline gases are abnormal by design - treat the change, not the number.

AdultAirwayGuideline

Also called: home NIV, domiciliary ventilation, home BiPAP, NIV, cough assist, mechanical insufflation-exsufflation, home ventilator

What it is

These patients use ventilatory support at home for chronic respiratory failure - COPD, obesity hypoventilation, neuromuscular disease (motor neurone disease, muscular dystrophy), chest-wall disease or central hypoventilation. Most use non-invasive ventilation (NIV / BiPAP) through a mask, usually overnight; some use a cough assist device to clear secretions; a minority are ventilated through a tracheostomy.

The trap is that their normal blood gases are not a well person's gases. Many run a chronically raised CO2 with renal compensation, so an ED must interpret an acute arterial gas against the patient's own baseline, not against a textbook range.

How to recognise it

The patient or carer brings their own machine, mask and settings, or an alert/passport document. A neuromuscular patient may also have a cough assist machine.
A history of overnight mask ventilation, a known diagnosis of COPD, obesity hypoventilation or neuromuscular disease, and often a specialist home-ventilation or respiratory team already involved.
On the gas, a raised bicarbonate with a near-normal or compensated pH points to chronic hypercapnia; a low pH with a high CO2 points to an acute deterioration on top of it.

What it gets confused with

Home oxygen supplies oxygen only; home ventilation moves air in and out and controls CO2. A patient may have both. Giving uncontrolled oxygen to a ventilation-dependent hypercapnic patient can worsen their CO2 - the device they need in a crisis is often their ventilator, not more oxygen.

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A minority of home-ventilation patients are ventilated through a tracheostomy rather than a mask. If the problem is the airway itself - a blocked or displaced tube - manage it on the tracheostomy (green) pathway, not as an NIV problem. If the problem is the ventilation (acidosis, device failure with a working mask airway), stay on this page.

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What goes wrong

Acute-on-chronic hypercapnic respiratory failure

Drowsiness, confusion, headache, flap, worsening breathlessness; a gas showing a high CO2 with a falling pH. Often triggered by infection, sedation or excess oxygen.

Red flag
A falling pH is the acute marker. The guideline threshold: a pH <7.35 and a PCO2>6.5 kPa defines acute respiratory failure, and persisting acidosis after initial therapy is the trigger to consider acute NIV.

Device or interface failure

Machine fault, mask leak or damage, tubing or filter problems, or a patient unable to tolerate their usual settings.

Red flag
A neuromuscular patient who cannot use their cough assist or ventilator can decompensate quickly. A patient who depends on the ventilator for most or all of the day, and loses the machine or circuit, needs manual ventilation (self-inflating bag) started at once - not escalation-and-wait; they can die within minutes. Escalate early.

Secretion retention

A neuromuscular patient with a weak cough, rising work of breathing and falling saturations because secretions are not clearing.

Red flag
This is a mechanical clearance problem. Their cough assist and physiotherapy matter as much as oxygen; involve the respiratory and critical care teams.

The first ten minutes

Assess ABCDE and get an early blood gas, interpreted against the patient's known baseline. Ask the patient or carer what their usual CO2 and settings are.
If the patient is ventilator-dependent and the machine or circuit has failed, start manual ventilation now - a self-inflating bag via their mask, or via the tracheostomy for a trache-ventilated patient - rather than waiting; a near-continuously dependent patient has minutes, not hours.
Titrate oxygen to a controlled target - for a patient at risk of hypercapnia that is typically 88-92% while you get gases, not high-flow oxygen (see the home-oxygen entry).
Treat the trigger: infection, pneumothorax, fluid overload, sedation. A deterioration in a stable home-vent patient usually has a cause.
Consider acute NIV early for acute hypercapnic acidosis. The guideline's modes-of-choice note: ventilators designed for NIV should be used, and A full face mask should usually be the first type of interface used.
Use the patient's own expertise and equipment where appropriate - their mask and settings are a known quantity - but acute NIV in the ED should be set up and monitored by staff competent to do so.
Decide the ceiling of care early and explicitly. Many of these patients have advance care plans; a neuromuscular patient may have a documented decision about intubation. Find it.

Do not

Do not chase a 'normal' CO2 or a normal saturation.

Chronic hypercapnia is this patient's baseline. Over-oxygenation can worsen CO2 retention, and normalising the CO2 acutely is neither the target nor safe. Treat the change from baseline and the pH.

Do not let NIV delay intubation when intubation is the right answer.

The guideline states that The use of NIV should not delay escalation to IMV when this is more appropriate. NIV is not a universal substitute for a definitive airway in a patient who is failing it.

Do not start acute NIV without a plan for what happens if it fails.

Acidosis alone does not preclude a trial of NIV, but the guideline ties that to an appropriate area with ready access to staff who can perform safe endotracheal intubation, and to a decided ceiling of care. Set both before you start.

Do not sedate casually.

Sedatives and opioids can tip a compensated hypercapnic patient into acute failure. If analgesia or sedation is genuinely needed, titrate cautiously and monitor CO2.

Who owns it

The respiratory / home-ventilation team owns the chronic device and settings, and critical care owns acute NIV and any escalation. The patient often has a named specialist centre. Tell them the baseline diagnosis, the usual settings, the current gas versus baseline, and any documented ceiling of care.

Who to call

The team and the criteria are national. The phone number is local, and this tool does not know it. Find it once, now, and write it on the department's own card — that is the part no website can do for you.

Say the device name first: Open with laryngectomy, LVAD, shunt — the single word changes who comes and what they bring. Do not bury it in the history.
Say what you have already established: Whether the device is patent, whether it has been removed or disturbed, and what you have already tried. The specialist is deciding whether to walk or run.
Ask who owns it out of hours: Device ownership and the on-call route often differ from the implanting specialty, and it is frequently a regional centre rather than your own hospital.
The patient's own team is a resource, not an afterthought: Named nurse specialists, home-care companies and device helplines answer questions nobody else can, and the patient usually has the number.

When the device is not the problem

A patient with a device gets pneumonia, sepsis, pulmonary oedema and myocardial infarction at the same rate as everybody else. The device is the most visible thing about them and it attracts the whole assessment.

The NTSP says it out loud: The project's own manual warns that patients with tracheostomies can become unwell with all the problems that other patients get too. It is easy to become fixated with the tracheostomy. The same sentence applies to every device in this tool.
Clear the device, then leave it: Establish that the device is doing its job — the stoma is patent, the line draws back, the pump is running — and then assess the patient as you would anyone else.
The anchoring runs both ways: The opposite error is treating a device complication as a medical illness: a blocked gastrostomy read as vomiting, a baclofen pump failure read as sepsis.

NTSP manual — Red flags · read in full

What the patient will be carrying

Many home-ventilation patients carry a ventilation passport or alert card with their diagnosis, settings and escalation plan, and neuromuscular patients often have an anticipatory care document. Ask for it on arrival.

Scope of this page

This page covers recognising the chronically ventilated patient who arrives acutely unwell and the first ED steps: interpret the gas against baseline, control oxygen, treat the trigger, consider acute NIV, and settle the ceiling of care. It does not teach how to set up and run acute NIV or invasive ventilation - those are delivered by respiratory and critical care staff competent to do so - and it does not cover chronic titration of home settings. It is written for adults: children on home ventilation (neuromuscular disease, central hypoventilation, tracheostomy ventilation) are a real ED presentation but are managed with paediatric anaesthesia / PICU and the child's own ventilation plan, and the adult BTS thresholds here do not apply to them.