Mechanical Ventilation

Mechanical ventilation is a life-support treatment in which a machine called a ventilator breathes for a patient who cannot breathe adequately on their own.

The ventilator pushes a carefully controlled mix of air and oxygen through a tube placed in the patient's airway and into the lungs. Each time the machine delivers a breath, it expands the lungs so that oxygen passes into the blood and carbon dioxide — the waste gas the body needs to expel — is pushed back out. The ventilator's settings are adjusted continuously by ICU (Intensive Care Unit) doctors and nurses so that the amount of oxygen and the rate of breathing always match what the patient's body needs at that moment.

Mechanical ventilation is used whenever a patient's breathing is so weak, fast, or laboured that the body can no longer get enough oxygen or remove enough carbon dioxide without help. It is always a response to a serious medical situation, not a planned elective procedure.

• Respiratory failure (the lungs stop working well enough to sustain life), from any cause
• ARDS — Acute Respiratory Distress Syndrome (sudden, severe inflammation that makes the lungs stiff and fluid-filled)
• Severe pneumonia (a serious lung infection causing breathing difficulty)
• During and immediately after major surgery, while the effects of general anaesthesia wear off
• Septic shock (a life-threatening body-wide infection that weakens breathing muscles)
• Severe asthma attack or COPD — Chronic Obstructive Pulmonary Disease (long-term lung disease) — that does not respond to other treatments
• Drug overdose or poisoning that suppresses the drive to breathe
• Neurological emergencies such as stroke, brain injury, or Guillain-Barré syndrome (a condition where the immune system attacks the nerves controlling the muscles, including breathing muscles)
• Cardiac arrest (when the heart stops), during and after resuscitation

Mechanical ventilation through a breathing tube is generally not used when it would not help the patient — for example, in some end-of-life situations where the patient or family has clearly chosen comfort-focused care instead. In those cases, non-invasive options or other supportive care may be discussed with the medical team.

Because mechanical ventilation is used in critically ill patients, risks come both from the underlying illness and from the ventilator itself. The medical team works continuously to reduce these risks, but they cannot always be avoided.

• VAP — Ventilator-Associated Pneumonia (a new lung infection that can develop because the breathing tube bypasses the body's normal defences against germs)
• Discomfort and agitation from having a tube in the throat, which is why sedation (medication to keep the patient calm and sleepy) and pain relief are given
• Barotrauma (lung damage caused by too much air pressure), which can lead to a pneumothorax (collapsed lung) in rare cases
• Muscle weakness from prolonged bed rest and the effects of sedation, including weakness of the diaphragm (the main breathing muscle)
• Difficulty weaning — some patients find it hard to breathe independently again after a period on the ventilator
• Accidental displacement of the breathing tube, which requires prompt repositioning
• Oral and throat irritation or injury from the tube over time
• Psychological effects such as anxiety, confusion, or delirium (a sudden state of mental confusion) during or after the ICU stay
• Blood clots in the legs (deep vein thrombosis) due to immobility, which can travel to the lungs (pulmonary embolism)

Because mechanical ventilation is almost always started in an emergency or during planned surgery, the patient rarely has time for the usual pre-procedure preparations. The steps below describe what the medical team does to prepare the patient and start ventilation safely.

When time allows — for example, before planned major surgery — the anaesthesiologist (the doctor who manages anaesthesia and breathing) will review the patient's medications. Blood thinners, diabetes medications, and certain other drugs may be paused according to the doctor's instructions. The patient is usually asked not to eat or drink for a set number of hours before a planned procedure, so that the stomach is empty and the risk of inhaling stomach contents is reduced. Smoking should be stopped as far in advance as possible, as it affects how the lungs respond.

Tests that are commonly done before or at the start of ventilation include:

• Arterial blood gas test (a blood sample taken from an artery to measure oxygen and carbon dioxide levels precisely)
• Chest X-ray, to see the current state of the lungs and confirm tube placement afterwards
• Blood tests including full blood count, kidney and liver function, and infection markers
• EKG (heart tracing) to check heart rhythm
• Pulse oximetry (a clip on the finger that reads oxygen levels in the blood continuously)

The procedure itself follows these general steps, though the exact sequence may vary depending on the clinical situation:

• 1. The patient is given sedation and, in most cases, a muscle-relaxing medication through a drip (intravenous line) to make the process comfortable and safe.
• 2. The doctor positions the patient's head to open the airway as widely as possible.
• 3. Using a laryngoscope (a lighted instrument to see inside the throat), the doctor guides an endotracheal tube (a flexible breathing tube) through the mouth or nose, past the vocal cords, and into the windpipe (trachea).
• 4. The tube position is confirmed — usually by checking for equal breath sounds on both sides of the chest, watching for the chest to rise, and with a chest X-ray.
• 5. The tube is secured with tape or a holder to prevent it from moving.
• 6. The tube is connected to the ventilator, and the initial settings — how fast and how deeply the machine breathes — are set by the ICU or anaesthesia team.
• 7. The patient is monitored continuously; settings are adjusted as test results and the patient's response guide the team.

While on the ventilator, the patient is monitored around the clock in the ICU. The goal is always to remove the breathing tube — a process called weaning or extubation — as soon as the patient is ready to breathe safely without it. This readiness is tested regularly and the timing is decided by the medical team based on the patient's progress, not a fixed schedule.

• Daily breathing trials: the team gradually reduces ventilator support to see how well the patient can breathe on their own; if the trial goes well, the tube is removed
• After the tube is removed (extubation), the patient is still watched closely in the ICU or a step-down unit for at least several hours, because some patients need the tube replaced
• Oxygen may be given through a face mask or nasal prongs after extubation to help the lungs adjust
• Physiotherapy (breathing exercises and, when possible, gentle movement or sitting up in bed) is usually started early to prevent muscle weakness and help the lungs clear secretions
• Nutrition is provided — often through a fine tube that passes through the nose into the stomach (nasogastric tube) while the patient is intubated, then by mouth when it is safe
• Blood thinners are often given to reduce the risk of blood clots during the period of immobility
• Mouth and throat care is performed regularly by nurses to keep the area clean and reduce infection risk
• Follow-up lung function tests, chest X-rays, or specialist review may be arranged after discharge depending on the underlying condition
• Some patients, particularly those who were ventilated for a long time, may experience lasting fatigue, muscle weakness, or psychological effects such as post-ICU anxiety; rehabilitation support and mental health care may be recommended by the team