Barts-MS rose-tinted-odometer: zero-stars
#T4TD (thought for the day)
How bad is your breathing and lung function?
Every year a few of our patients with advanced MS die. During the first COVID-19 lockdown I received an email from the husband of one of my patients I had been looking after for over a decade. Thankfully she died peacefully in her sleep. Her MS had affected her swallowing to such an extent that she had to have a feeding tube inserted into her stomach for feeding. Prior to the feeding tube, she was getting recurrent chest infections. Her speech was also very poor and at times I couldn’t really understand what she was saying. Her other complications included intermittent pressure sores and frequent bladder infections.
A common cause of unscheduled hospital admissions and sadly death is aspiration pneumonia. This is when people with MS have poor coordination of their swallowing mechanism and instead of swallowing saliva and/or food properly some of it travels down the trachea or windpipe into their lungs and causes pneumonia.
At the same time, people with swallowing difficulties may have weakness of their muscles of respiration, in particular, the diaphragm. The cause of diaphragmatic weakness is usually lesions in the upper cervical spine. However, it is often made worse by poor posture. For the diaphragm to work properly it needs to be able to move downwards into the abdominal cavity without being impeded; sitting upright and not hunched over help. Seeing a physiotherapist is important to correct your posture and to make sure your wheelchair if you are using a wheelchair, has the correct postural supports. There has been a lot of wheelchair innovation recently with the production of bespoke moulded body supports to keep you sitting straight and upright.
When the diaphragm is weak the so-called accessory muscles of respiration help a person breath. The accessory muscles lift the thorax or chest as the weak diaphragm pushes downwards. The accessory muscles actually work as a pulley and then rely on gravity to lower the chest. So for the accessory muscles to work well you need to be sitting upright; as soon as you lean back or lay down you reduce the effect of gravity and the accessory muscles’ ability to function as a pulley.
When we look at how well your breathing capacity is we often measure your so-called vital capacity, i.e. how much air you can move in and out of your lungs. A normal vital capacity is around 60-70 mL/kg; so a 70kg person has a vital capacity of about 4.5-5.0 litres. When the vital capacity drops below about 20-30ml/kg it is associate with a reduced ability to cough and move mucus plugs out of your lungs. When your cough reflex is weak it puts you at risk of segments of the lung collapsing (atelectasis) and becoming infected.
When your vital capacity drops below 15mL/kg you are in serious trouble and are likely to be in or close to respiratory failure and your blood gases (oxygen and carbon dioxide) may be affected.
When I was a trainee neurologist in South Africa we used to carry around a vital capacity flow metre on our ward consult rounds. This was to assess respiratory function in patients admitted with paralysis from nerve or muscle disease. These vital capacity meters were expensive and in short supply and we didn’t own them and some hospitals didn’t have them. Nowadays you can purchase relatively cheap vital capacity meters that connect to a smartphone.
At Baragwanath hospital, now called the Chris Hani hospital, in Soweto (South Western Township) outside Johannesburg, we used to use low tech clinical signs. The first was how many numbers could someone count at a rate of one number per second on a single breath-hold, whilst sitting-up. If the person couldn’t get to 12 they needed to be seen by the respiratory intensive care team. The other test was whether or not the patient could blow out a lit match or candle held 30cm from their face. The use of a lit match or candle was not really allowed on the wards because of the fire risk, particularly if patients were on oxygen therapy, but the Baragwanath consultants ignored health and safety and used the test anyway. It is important to realise that if someone can’t blow out a lit match or candle at 30cm then their ability to cough is likely to be compromised and they are therefore likely to at risk of collapsing part of their lung and getting a serious lung infection.
Another important clinical sign is simply to listen to a person speak. If their speech is not smooth, but soft and broken up with frequent pauses to take a breath, also indicates a problem with their breathing. You can also ask the person to cough; if the quality of the cough is poor and weak that can also be taken as a sign of weak respiratory muscles.
A mistake that many people make is to use a so-called peak flow meter and pulse oximeter to monitor lung function. These two devices are not suitable for pwMS. The peak flow is really best for people with asthma and bronchospasm and the peripheral blood oxygenation as measured with a pulse oximeter only becomes abnormal very late. Although a pulse oximeter is good to monitor lung function when you have an infection, such as COVID-19 pneumonia, or when someone has a pulmonary embolus (blood clot in the arteries to the lung) it is not a good measure of your respiratory reserve.
If you have advanced MS with swallowing or breathing problems you may want to self-monitor yourself. You need to see a speech therapist to have your swallowing assessed. If your swallowing is compromised you may need to change your diet; for example, if you are choking or coughing when drinking liquids you may need to use thickened liquids. It is also important to have regular home chest physiotherapy to prevent sections of your lung collapsing and to lung muscle exercises. The physiotherapists use so-called incentive spirometers to make the lung exercises fun. I know all about these devices; I had to do incentive spirometry four times a day in the first few weeks after my accident to prevent lung atelectasis.
It is also important that your family and carers have basic first aid training and can do a pharyngeal sweep and/or Heimlich manoeuvre to dislodge food stuck in your throat. Portable pharyngeal suction or vacuum devices can also be purchased and kept at home to clear the throat. If you go this route then your carers and family will need to be trained in how to use them.
If this post is relevant to you because you have advanced MS or you have a family member or patient with advanced MS it is important to ask them if they have an advanced directive. An advanced directive is a legally binding document setting-out how you want to be managed if you ever end up with life-threatening medical complications of having MS. For example, do you want advanced life support or not? It is important that your family doctor, hospital team, family members and carers have a copy of this directive so that they can ensure your wishes are carried out if ever the need arises.
Finally, please make sure you have had your vaccine requirements reviewed. You need your annual flu vaccine, the pneumococcal vaccine if you have not had one on the last 5 years and a COVID-19 vaccine.