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A 64 year old woman with headache and breathlessness

BMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e3158 (Published 15 May 2012) Cite this as: BMJ 2012;344:e3158
  1. Robert Lord, core medical trainee,
  2. William Flight, clinical fellow ,
  3. Alan Sweeney, core medical trainee ,
  4. Nauman Chaudhry, consultant respiratory medicine
  1. 1University Hospital of South Manchester, Manchester M23 9LT, UK
  1. Correspondence to: R Lord roblord{at}doctors.net.uk

A 60 year old woman presented to the chest clinic with four years of worsening dyspnoea. On waking she felt unrefreshed and had a headache. She felt sleepy throughout the day. Her medical history included kyphoscoliosis, spina bifida, hypertension, and osteoporosis. The drugs she was taking included amiloride, furosemide, nitrazepam, and calcium-vitamin D supplements. She was born in the United Kingdom, was a lifelong non-smoker, and a retired teacher. She owned no pets and reported no exposure to asbestos.

On physical examination, her respiratory rate was 28 breaths/min and oxygen saturation was 86% on ambient air. Temperature and haemodynamics were normal. General inspection showed marked kyphosis and rapid shallow breathing. She had a global reduction in breath sounds but no crackles, wheeze, or rub. The rest of the examination was unremarkable, with no evidence of right heart failure.

Blood tests showed a raised haemoglobin of 157 g/L (reference range 115-165), but other haematological, biochemical, and inflammatory markers were normal. Arterial blood sampling on ambient air showed pH 7.36, arterial carbon dioxide tension 9.14 kPa, arterial oxygen tension 6.4 kPa, base excess 7.8, and bicarbonate 33 mmol/L. Her body mass index was within the normal range. Figure 1 shows the chest radiograph.

Questions

  • 1 What is the primary abnormality on the chest radiograph?

  • 2 Why would this abnormality cause her symptoms?

  • 3 What investigations would you perform to evaluate the underlying disorder?

  • 4 How should she be managed?

Answers

1 What is the primary abnormality on the chest radiograph?

Short answer

The primary abnormality of the chest radiograph is severe kyphoscoliosis with profoundly reduced lung volumes.

Long answer

This radiograph shows kyphoscoliosis with predominantly left lateral mediastinal displacement. Lung volumes are profoundly reduced, and this is more marked on the left. The left hemidiaphragm is raised with the gastric bubble visible within the left hemithorax. There may be a mild degree of cardiomegaly, but the thoracic asymmetry makes it hard to quantify this precisely. The visualised lung fields seem clear.

2 Why would this abnormality cause her symptoms?

Short answer

Kyphoscoliosis leads to deformity of the ribcage, which dramatically restricts chest wall movement and the effectiveness of the respiratory muscles. The ensuing alveolar hypoventilation leads to hypercapnic respiratory failure and the associated symptoms of morning headaches, daytime sleepiness, and dyspnoea.

Long answer

Kyphoscoliosis is a pathological anterolateral curvature of the spine. It causes a ribcage deformity that impairs inspiratory movements and reduces the efficiency of the respiratory muscles. In combination, these restrict chest wall movements and lead to reduced lung volumes and alveolar ventilation. The consequence of this reduction in ventilation is hypercapnic (type 2) respiratory failure.1 2

Kyphoscoliosis may be idiopathic or associated with neuromuscular, vertebral, or connective tissue disorders including spina bifida.1 Similar presentations occur in other restrictive thoracic disorders, such as post-poliomyelitis syndromes, ankylosing spondylitis, and after thoracoplasty for tuberculosis.2

The hypercapnia initially begins during REM sleep, when all the respiratory muscles except the diaphragm are paralysed. This further reduces the efficiency of respiration.3 4 As the condition progresses, ventilation becomes impaired during non-REM sleep. Because this comprises the majority of normal sleep, a more serious and prolonged rise in carbon dioxide tension occurs. This leads to the typical hypercapnic symptom of morning headache. In end stage disease, patients have daytime hypercapnia and excessive sleepiness.1 Progressive dyspnoea caused by the increased work of breathing accompanies this sequence.5

Respiratory failure as a result of kyphoscoliosis is usually slowly progressive, but it may be accelerated by factors such as obesity. Concomitant use of sedatives such as benzodiazepines or alcohol can lead to a further deterioration in respiratory status. Acute decompensation as a result of pneumonia, pulmonary embolism, or cardiac failure is seen in a proportion of patients.

3 What investigations would you perform to evaluate the underlying disorder?

Short answer

Overnight pulse oximetry and transcutaneous monitoring of carbon dioxide followed by analysis of early morning arterial blood gases will confirm the presence of alveolar hypoventilation and evaluate its severity.

Long answer

The case history suggests chronic progressive respiratory failure. Overnight pulse oximetry and transcutaneous monitoring of carbon dioxide followed by analysis of early morning arterial blood gases will confirm the presence of alveolar hypoventilation by showing a rise in carbon dioxide saturation and fall in oxygen saturation.6 Oximetry may identify evidence of upper airway obstruction suggestive of coexistent obstructive sleep apnoea-hypopnoea syndrome. If this diagnosis is suspected clinically, a more detailed respiratory channel polysomnography study may be helpful.

Once the patient is stable, perform a full set of pulmonary function tests to confirm the presence of a pure restrictive defect. In cases with a suggestion of coexisting neuromuscular disease, a neurological consultation must be sought and investigated with muscle biopsies and electromyography. Measurement of maximal mouth inspiratory and expiratory pressures and sniff nasal inspiratory pressure may be helpful.

4 How should this patient be managed?

Short answer

The most important aspect of her treatment is correction of hypoventilation through the use of non-invasive positive pressure ventilation (NIV). Hypoxia is most safely corrected by entraining oxygen through the NIV circuit. Extreme care should be taken with other forms of oxygen therapy because of the risk of a substantial rise in arterial carbon dioxide tension.

Long answer

The most important aspect of managing chronic ventilatory failure is correction of hypoventilation with non-invasive positive pressure ventilation (NIV) via a facial or nasal mask. Some patients achieve satisfactory oxygenation with NIV alone, but many require supplemental oxygen to be entrained through the NIV circuit, with careful titration according to oxygen saturation and blood gases. Cor pulmonale can occur if severe hypoxia is left untreated.

A wealth of observational data support the long term use of NIV in patients with kyphoscoliosis and those with ventilatory impairment as a result of tuberculosis or its treatment, including thoracoplasty. These data support consideration of long term NIV in most restrictive thoracic disorders.1 Long term NIV improves symptoms, physiological parameters, and survival.7 8 9 10 11 Several observational studies have shown five year survival rates of over 75% with NIV. Data from 244 patients with respiratory failure as a result of kyphoscoliosis show a clear survival benefit with NIV over long term oxygen therapy.9 NIV has also been shown to improve quality of life in kyphoscoliosis.7 However, no data from randomised controlled trials are available to date.

The timing of institution of NIV in kyphoscoliosis must be judged on an individual basis. Consensus conference guidance has been published to aid this decision and recommends NIV in the following circumstances6:

The presence of symptoms (such as fatigue, dyspnoea, and morning headache) and one of the following:

  • Arterial carbon dioxide tension of 6 kPa or more

  • Nocturnal oximetry showing oxygen saturation of 88% or less for five consecutive minutes.

An acute respiratory deterioration in patients with a longstanding restrictive thoracic defect would be managed differently from our case. The aim here is to correct a potentially life threatening hypoxia. For those not already established on NIV the British Thoracic Society guidelines on the emergency use of oxygen should be followed.12 Controlled oxygen therapy should be given via a Venturi mask to achieve target oxygen saturations of 88-92%. Such an approach attempts to minimise the risk of worsening hypercapnia attached to rising oxygen levels. However, in a good proportion of patients this will be insufficient and acute NIV will be needed to allow safe oxygenation.

Patient outcome

Our patient was admitted electively and started on non-invasive ventilation with the settings titrated according to transcutaneous carbon dioxide measurements. Over the course of her admission, she was weaned from daytime NIV and advised to continue nocturnal use of the machine indefinitely. On discharge her NIV machine was set up in pressure control mode with an inspiratory pressure of 36 cm water and expiratory pressure of 4 cm water. Oxygen at 1 L/min was entrained to the NIV circuit to maintain adequate nocturnal oxygenation. At review three months after discharge she was tolerating NIV well and her symptoms of early morning headaches and breathlessness had settled. Her haemoglobin had fallen to 146 g/L. Arterial blood sampling on air showed pH 7.38, arterial carbon dioxide tension 6.4 kPa, arterial oxygen tension 8.7 kPa, base excess 5.5, and bicarbonate 29.0 mmol/L. She has been advised that lifelong use of nocturnal NIV will be necessary.

Notes

Cite this as: BMJ 2012;344:e3158

Footnotes

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Patient consent obtained.

References

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