Weaning

Monday 20th April 2020

COVID Figures for 19th April

UK Hospital Deaths 596 / Total 16,060

James Cook Hospital – Total deaths – 134

Another virtual pub-night last night. They’re just nowhere near as much fun as the real thing. The trouble is that no-one is actually doing anything anymore. All my friends are in lockdown and this does not generate many amusing anecdotes. The conversation got middle-aged very quickly when Frans and Mike started to discuss plumbing fixtures and fittings. On the plus side, I’m delighted to report that Fergus, after his shambolic appearance last time (https://www.nomoresurgeons.com/post/virtual-pub) had upped his game. When he appeared on-line he was to be found resplendent in a suit and tie! Quite the transformation - I fear I may have been too hard on him before. After the first beer he ducked out to change into a t-shirt. He claimed he was too hot and uncomfortable. I suspect he just needed a break from the conversation about push-fit vs. solvent-weld waste pipe connections…

Today I caught up on how my friend Gary is doing. He remains ventilated in Intensive Care down in London. He is slowly improving but has been ventilated for the past three weeks as a consequence of COVID pneumonitis. He is still on dialysis after developing kidney failure and has undergone two unsuccessful attempts to remove the breathing tube.

The process by which a ventilated patient begins to breathe by themselves and come off the ventilator is called weaning. For most people the term invokes happy memories of babies chewing on Farley’s Rusks but instead of moving from milk to solid food, the ICU patients are moving from not breathing to breathing independently.

This can be a surprisingly slow process. The longer you are ventilated the weaker your respiratory muscles become and the harder it is to start breathing by yourself again. Pre-existing chest and heart problems make this a lot worse.

The first step to weaning is to make sure the underlying disease is better; the reason you needed the ventilator in the first place has to have improved. Most of the time this means no longer needing high concentrations of oxygen and demonstrating that you can take large enough breaths by yourself without the help of the ventilator. For the COVID patients this can take 2-3 weeks or longer.

The second step is to make sure that any factors that might impair breathing are addressed. For example, a distended abdomen following bowel surgery can compress the lungs, kidney failure can make you very drowsy and cause a build-up of acid in the blood making it hard to breathe and brain or spinal cord injuries may affect breathing. Heart failure can also cause problems as the blood flow through the lungs can be compromised.

Slowly the amount of respiratory support that the ventilator provides is decreased until, after a period of time, the patient requires minimal help from the ventilator. This can take days, weeks or occasionally months. Once the patient is able to demonstrate that they can breathe well then a decision is taken whether to remove the breathing tube. As well as being able to breathe spontaneously the patient also needs to be able to cough well. Build-up of lung secretions or sputum can occur within 24-72 hours causing new respiratory failure and re-intubation (re-insertion of the breathing tube)

For patients who cannot cough well, or patients who are unlikely to tolerate removal of the breathing tube in the short-term, a tracheostomy can be performed. A shorter breathing tube is brought out through a hole in the neck. This is more comfortable and makes caring for the patient easier. It can allow a longer period of time for the patient to come off the ventilator and most importantly, allows the clearance of lung secretions using suction catheters until such time that the patient develops a stronger cough.

The trachcostomy is a small operation that is usually performed by the ICU team on the Intensive Care Unit. It is usually temporary and heals up spontaneously with a small scar once the patient is better and the tracheostomy tube is removed.

The decision when to extubate, when to wait or when to perform a tracheostomy is not always straightforward and comes down to experience. If a breathing tube is removed too early there is a risk of failure causing a setback in the patient’s progress. If too late, then there is a prolonged ICU stay and the risk of further complications. There are also risks associated with tracheostomy, such that one needs to be certain that it is needed before proceeding. It is difficult to get all of this right all the time.