A&E / Emergency Care in Patients with Neuromuscular Disorders

General information

NMDs are usually genetic conditions that causes a gradual deterioration in muscle strength and ultimate loss of ambulation and wheelchair dependency. As a result of increased supportive care these patients are now staying ambulant for longer and living longer due to treatment of symptoms that can accompany the disease, notably cardiac involvement and respiratory failure. Despite impaired mobility it is a condition compatible with a good quality of life, and in an emergency medical situation requires appropriate and proactive management.

NMDs affect muscles in both the lower and upper limbs and ambulation is reduced. It also affects heart and respiratory muscles and the treatments that are used, include steroids in DMD and bisphosphonates, can cause side effects. The steroids used most commonly are prednisolone or deflazacort at 0.75mg/kg or 0.9mg/kg daily respectively. These can have an effect on the ability to deal with infection but also cause gastrointestinal problems, increased osteoporosis (with a potential for increased fracture risk) delayed puberty, weight gain and cushingoid appearance.

As a consequence it is vital to have a high index of suspicion about potential side effects of steroids- parents need to notify medical staff that they are on steroids, what steroid and what dose and may require a top up dose due to their illness or that being on steroids may itself indeed mask the usual signs of illness.

Important to consider in DMD:

Cardiac failure _HR & RR, no fever, collapse refer cardiology section
Respiratory failure _or _RR, _C02 refer respiratory section
Chest infection _RR, _HR & fever refer respiratory section
Peptic ulceration refer gastrointestinal section
Adrenal crisis _BP, _glucose, shock refer steroid section

Caution:

Depolorising muscle relaxants are contraindicated.
Use supplemental oxygen with caution due to risk of hypercapnia.
Omission of steroids for more than 24 hours.

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Anaesthesisa and Surgery

This should ideally be done in a hospital with full service, PICU facilities and staff familiar with the care of Duchenne. There are a number of issues in providing anaesthesia for these patients, mainly respiratory but also consideration needs to be given if on steroids for steroid cover during the stress period of surgery. The exclusive use of a total intravenous anaesthetic (TIVA) technique is strongly recommended, due to the risk of malignant-hyperthermia-like reactions and rhabdomyolysis when patients with Duchenne are exposed to inhalational anaesthetic agents. Depolarizing muscle relaxants like succinylcholine are absolutely contraindicated due to the risk of fatal reactions.

In an emergency - appropriate referral is required:

If a child is ambulant with no respiratory compromise - needs referral to an anaesthetist with paediatric experience.
If a child is non-ambulant and has respiratory involvement (FVC <1.5L or <50%) - needs referral to the nearest hospital with PICU facilities once stabilised.

Remember:

DO NOT use depolorising muscle relaxant

DO cover for ‘stress’ if required when a child is on steroids.

To prevent the risks particularly post operative failure to extubate, atelectasis and pneumonia, appropriate assessment pre-surgery is required. If the pre-operative respiratory function is sub-threshold then non-invasive ventilation and cough assist techniques will need to be employed post surgery and these techniques need adequate training preoperatively to ensure a smooth course.

Pre-operative training in manual assisted cough techniques necessary:

Baseline peak cough flow is <270LPM
Baseline maximum expiratory pressure is<60 cm water (Older teenage and adult values)

Preoperative training in the use of nocturnal non-invasive ventilation is:

Strongly recommended if baseline FVC <50% predicted
Necessary if baseline FVC<30% predicted

After careful consideration of the above, patients may be eligible for surgery, albeit with increased risk, if preoperative training has been completed in assisted cough techniques and non-invasive ventilation.

Use of opiates

It is well documented that whilst the use of certain anaesthetics can cause malignant hyperthermia like reactions, Opiates are also potentially hazardous for this group of patients. There appears to be an increase in the susceptibility to opiates with enhanced respiratory depression and poor cough technique which is particularly important in patients who are admitted with a chest infection. If the need to use opiates arises with difficult to control pain etc short acting opiates or barbiturates should be used. There should be close monitoring of these patients if opiates are used and respiratory function testing including CO2 monitoring should be employed. Supplemental oxygen should not be given to a patient with Duchenne after opiates administration without careful assessment as they may require assisted ventilation and supplemental oxygen would cause further deterioration in the state of hypercapnia.

In hospital:

Assess Airway, Breathing and Circulation
If required use short acting opiates

Regularly assess:

Oxygen saturation - if dropping, do not supplement with O2 without checking CO2.
Normal CO2 - oxygen therapy
Increased CO2 - ventilation support
Temperature
Pain score

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Cardiovascular Disease

Possible problems

Hypertension: Secondary to steroids, particularly in younger, ambulant boys
Cardiomyopathy: More common in non-ambulant teenagers
Tachycardia: Commonly noted feature of the disease and also noted in systolic dysfunction. New onset sinus tachycardia with no clear aetiology warrants prompt cardiology assessment.9 Abnormalities in cardiac rhythm should be promptly investigated with Holter monitoring or an event monitor recording, and treated.

In hospital:

Cardiovascular compromise – needs urgent assessment.

Assess airway, breathing and circulation

Assess O2 saturation, treat with O2 carefully and monitor O2
Fluid balance - may need restricted +/- diuretics
Early discussions with local cardiology team or their specialist

Patients with Duchenne develop left ventricular dysfunction and there is evidence that early treatment with ACE inhibitors and beta blockers can be cardio protective. Cardiac function is regularly assessed every 2 years under 10 years and then annually after that. Please see sheet for recent cardiac function.

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Fractures

Patients with Duchenne are more liable to suffer from fractures for a number of reasons:

Less mobile and fall frequently.
Decreased bone density even in steroid naïve patients.
Steroid treatment reduces bone mineral density.

In hospital:

Ambulant patients should ideally be treated with internal fixation which aids early mobilisation, however careful consideration should be taken regarding anaesthetic risk (see anaesthesia section). The safest and fastest way to promote healing should be adopted. Early contact with physiotherapy is essential to encourage continued ambulation. Periods of immobility can lead to permanent loss of ambulation.

In non ambulant patients, requirement for internal fixation is not as acute and therefore splinting or casting of a fracture is appropriate. NB. Casting should be in a good functional position. Vertebral fractures should be treated with IV bisphosphonates, in conjunction with a bone specialist/endocrinologist.

After care

If not on bone protection - consider referral to endocrinologist for preventative treatment especially if on chronic steroids.

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Gastrointestinal Problems

Possible problems

In NMD gastrointestinal problems can range from poor oral intake and dysphagia with possible aspiration episodes with advancing disease but more commonly they are prone to constipation but more important is the possibility of peptic ulceration and abdominal pain - this is more frequently associated due to the treatment with steroids, as seen in DMD.

Gastritis is also experienced by patients who are taking oral bisphosphonates for bone protection. If gastric reflux is suspected then treat with proton pump inhibitors or H2 blockers, with prokinetics, sacrulfate and neutralising antacids as adjunctive therapies

In hospital

If presents with abdominal pain, vomiting or frank haematemesis – needs urgent assessment.

Assess Airway, Breathing and Circulation

If obvious ulceration, fluid replacement, treatment with anti-ulcer medication, including proton pump inhibitors, and urgent referral to the surgeons/gastro team. Advise against NSAIDs.

Other common gastrointestinal problems in NMD patients;
Poor oral intake and dehydration
Aspriation episodes
Constipation
Peptic Ulceration - signs may not be obvious in younger boys on steroids

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Respiratory management

Respiratory infections need prompt treatment with antibiotics to prevent deterioration as well as regular physio to help clear secretions. Most ambulant patients will have good respiratory function and cough, however once non-ambulant the risk of respiratory complications increases and some of them may need help with assisted coughing techniques, respiratory physiotherapy, and volume recruitment techniques including cough assist machines or Ambu-bag, therefore early intervention and close monitoring is paramount. Once the FVC starts to deteriorate, boys are susceptible to chest infections and very vulnerable when FVC <50% or <1.5L. Ventilation may be required.

In hospital

Assess Airway, Breathing and Circulation
Contact their specialist team who may have information that may be pertinent to their care.

In younger, ambulant boys:

with mild/no fever and well, treat with oral antibiotics and review in 24 hours.
with fever and unwell – Admit, Intravenous antibiotics and physio.
Monitor respiratory function (FVC & CO2)
If O2 required, check CO2 level (do not treat with O2 indiscriminately) Assisted ventilation may be required.

In older +/- non-ambulant patients +/- ventilated:

Assess FVC - if baseline FVC when well is <1.5L or <50% they are very vulnerable
if FVC >2L or >50%, no/mild fever and well, treat with oral antibiotics and review in 24 hours
if FVC <50% or <2L, fever and unwell – Admit, Intravenous antibiotics
Monitor respiratory function (CO2 and FVC)
If O2 required, check CO2 (do not treat with O2 indiscriminately)
May require non invasive ventilation during admission

In patients already ventilated at night and unable to perform own FVC - assess CO2
If increased - may need ventilation during the day with infection

Seek specialist help from home ventilation team. When contacting them have the following details ready:

type of machine
usual settings
length of time using night time ventilation
CO2 levels
date last seen by ventilation team

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Steroid treatment

Do not omit the steroid dose for more than 24 hours – this can be dangerous!

Many patients with duchenne are being treated with corticosteroids, mainly prednisolone or more rarely deflazacort. This poses potential problems aside from the gastritis mentioned in the section about gastrointestinal problems. Of particular significance is the fact that patients on long term, high dose steroids may develop secondary adrenal insufficiency. This is due to chronic suppression of Corticotrophin- Releasing Hormone (CRH) and corticotrophin hormone (ACTH) production from the hypothalamus and pituitary gland respectively. The major implication of this is that when people on steroids are ‘stressed’ due to intercurrent illness or at the time of an operation they may not be able to mount the usual ‘stress’ response and produce the extra steroid required at such times. They may then show signs of adrenal insufficiency which can include:

Vomiting
Hypotension (low blood pressure)
Hypoglycaemia (low blood sugar)
Altered consciousness
Dizziness

Patients may be found to have a low sodium at such times which in this context typically reflects water overload (cortisol is needed to excrete water) rather than lack of adequate mineralocorticoid activity. Recovery of the hypothalamic-pituitary-adrenal axis can take many weeks or months when steroids are reduced or stopped which should be borne in mind when patients have recently stopped taking steroids. The following are therefore the key considerations for parents, carers and health professionals when a patient is taking or has recently been taking high dose steroid:

1. Children and adolescents on steroids may need ‘extra’ doses at the time of significant illness.

2. If a child has a vomiting illness then they may not be able to take their steroids by mouth and so may need steroid therapy (eg hydrocortisone) by drip or by injection until they can take medication by mouth once again.

Guideline

If a child has vomited their steroid dose within an hour of taking it, give the same dose again.
If a child has a vomiting illness and is not eating, give the steroid dose after cessation of vomiting (together with a small ‘sip’ of fluid if this helps them to take it). Do not omit steroids for more than 24 hours.
If vomiting continues you will need to contact your GP or doctor.
If a child is unwell with a temperature but can manage oral steroids, then increase the steroid dose to 12 hourly from once daily, until the child is well again.
If a child has not managed their steroid dose for 24 hours then they need to be reviewed and given injectable steroids if oral therapy still cannot be tolerated. Contact your GP or contact your consultant involved in your care for advice. The child / patient may need to attend A&E to be assessed and given appropriate care.
If a child lives in a remote area that is far away from hospital departments, they may be supplied with an injectable form of steroid to use in the event of a vomiting illness (eg. hydrocortisone 100mg per dose). This will enable families to treat potential steroid deficiency whilst on the way to hospital or waiting for help.
Surgical procedures will require steroid cover – make sure all doctors are aware of the fact that the child is on steroids.

In hospital

Measure blood gas, glucose and electrolytes as a priority. Consider taking blood for measurement of cortisol and ACTH:

If hypotensive, give 20ml/kg bolus of isotonic saline to restore blood pressure.
If hypoglycaemic, give 5ml/kg of 10% dextrose or equivalent followed by a Saline / dextrose infusion to prevent recurrence. Administer fluid cautiously – remember patients may be relatively fluid overloaded at presentation
Hydrocortisone should then be given in a dose of 50 - 100mg intravenously or intramuscularly (given it works more slowly) every 4 to 6 hours.
In young children <16kg or less than 4 years, a smaller dose of 25mg every 4 to 6 hours can be given.
The steroid regimen will need to be reviewed on regular basis althoughpatients can usually return to oral medication when they are recovering.

Estimated equivalent values are as follows:

1mg prednisolone = 4-10mg hydrocortisone
1mg dexamethasone = 50-100mg hydrocortisone

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