Professor Michael Polkey, consultant respiratory physician, and Dr Cordingley, consultant in intensive care medicine, discuss the pitfalls of mechanical ventilation and why a respiratory weaning service may be needed.

Q. What is mechanical ventilation and why is it needed?

A. Mechanical ventilation is the process of connecting a patient to a machine that is able to do the patients breathing for them. Patients are usually put on a mechanical ventilator during a medical emergency or to maintain normal breathing during an operation. The ventilator is connected to the patient by a plastic tube called an ‘endotracheal’ tube which is placed in the upper airway through the mouth by an anaesthetist.

Q. Why is mechanical ventilation a problem?

A. Despite its life-saving benefits, mechanical ventilation carries with it many risks. First of all, the endotracheal tube in the windpipe makes it easier for bacteria to get into the lungs, increasing the risk of pneumonia. Secondly, the act of pushing air into the lungs (particularly when lungs are already diseased or damaged) can cause lung injury, or lung collapse (pneumothorax). Finally, side effects of medication to help relax the patient can build up in the system and cause patients to remain in deep sleep for hours or days.

Q. Given the risks, why not take the patient off the ventilator once the operation or medical crisis is over?

A. Since the tube is inserted through the upper airway, the patient has to be sedated with drugs. Once the patient is past the acute crisis, or their surgery is over, the doctors will try to get the patient to breathe for themselves.

In most cases this process works without problems, but with a few patients it is impossible to remove the endotracheal tube at the first attempt. The reason for this is usually due to underlying medical conditions such as lung disease, heart disease, muscle weakness or retention of sputum in the airway, all of which impede independent breathing.

In the event that removal of the endotracheal tube is unsuccessful, then the patient will require ‘weaning’ from mechanical ventilation if they are to resume a normal life - or indeed to leave the ICU.

Q. Is there anything that you can do to prevent dependence on mechanical ventilation?

A. When local physicians identify that patients will be difficult to wean, a tracheostomy is often performed. In this procedure, a small hole is created in the main airway just below the voice box and the ventilator may then be connected to a plastic tube in the hole. We endorse this approach because it not only allows the sedating drugs to be reduced, or even stopped, but also enables the patient to sit out of bed or stand more easily.

Q. Can you tell me more about the respiratory weaning service on offer at Royal Brompton Hospital?

A. At Royal Brompton Hospital, we provide a consultant-led multidisciplinary approach to ensure that the patient has the best chance of weaning from mechanical ventilation.

We are fastidious about addressing all the factors which might limit a patient’s ability to breathe. For example, improving cardiac function or the application of specialised techniques to aid sputum expectoration.

A key technique with which we have a lot of experience is the use of non-invasive ventilation to allow the patient to ‘bridge’ from tracheostomy ventilation. With this approach, the support of the ventilator is given by a tightly fitting face mask from a ‘low-tech’ ventilator, suitable for use on the general ward or even at home. Once we are happy that the patient can breathe easily with this device, the tracheostomy is withdrawn.

Q. How is the weaning programme managed?

A. Typically, a consultant from our weaning service will retain overall vision of the patient’s progress throughout their stay. They will visit the intensive care unit, often daily, to assess the patient’s progress, liaise with the intensive care staff and consult with the patient’s family.

The intensive care consultants rotate on a weekly basis, but when ‘on service’, will review the patient twice daily and maintain regular liaison with the lung failure team. Although the programme is primarily consultant-led, we take pride in our strong multidisciplinary team which encompasses physiotherapy, dietetics, speech therapy and occupational therapy.

Q. What happens after weaning?

A. After patients have been weaned off mechanical ventilation, they will be transferred to the high dependency unit, and once their condition improves, onto the general ward. Tests and further treatment may be administered to reduce the likelihood of mechanical ventilation being required in the future.

We will arrange for non-invasive ventilation as an inpatient, and subsequently as an outpatient, and work with the patient to determine length of treatment using this type of ventilation. Depending on the underlying diagnosis, the patient may require input from other specialities.

In this respect, Royal Brompton Hospital is well positioned, boasting excellent links with other central London hospitals both in the NHS and in the private sector.

Q. What happens if the patient can’t be weaned?

A. In the few cases where patients cannot be weaned from tracheostomy ventilation, the weaning team can advise on the equipment and facilities needed to create a home tracheostomy ventilation programme, which can safely maximise the patient’s quality of life.

Q. How are patients referred for weaning treatment?

A. Royal Brompton Hospital is the UK's national centre for heart and lung disease and therefore receives referrals from surrounding intensive care units that find their patients difficult to wean.

We also welcome referrals from overseas and already have established links with intensive care units across the Middle East. In the past, our service to overseas patients was limited by the number of side rooms available to us.

We are pleased to announce that we have recently opened two new rooms and plan to open two further rooms, should we receive sufficient interest. Patients from overseas can be confident that we’ll make their stay as comfortable as possible. Our international patients liaison team, for example, provides interpretation services, as well as logistical, practical and emotional support.

To enquire about the respiratory weaning service at Royal Brompton Hospital, or to refer a patient, please email:


Professor Michael Polkey

Consultant respiratory physician