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The respiratory tract is considered in two parts, upper and lower. The upper respiratory tract (URT) comprises:

  • Nose
  • Sinuses (air-filled cavities within cheekbones and forehead)
  • Mouth (including the tonsils)
  • hroat
  • Larynx (adam’s apple, part of the throat; contains the vocal cords)
  • Pharynx, at the back of the throat (prevents foreign bodies entering the trachea)

The lower respiratory tract (LRT) comprises:

  • The trachea: divides to form two bronchi, which divide to form
  • Bronchioles, tiny airways throughout the lungs, which end in
  • Alveoli, thin-walled air sacs, numbering about 3 million, where gas exchange takes place.

Role of the respiratory system

The prime function of the respiratory system is to maintain the exchange of oxygen and carbon dioxide in the lungs and tissues, and regulate the acid-base balance. Any change in this system will affect, and may present in, other body systems. Gas exchange between air and the bloodstream is a rapid process that takes place in the alveoli. An adequate supply of oxygen to the tissues depends on sufficient ventilation (air flow) and perfusion (blood flow) of the lungs. Impairment of either, e.g. by airway narrowing in uncontrolled asthma or left ventricular failure, may reduce the oxygen supply and lead to a raised concentration of carbon dioxide in the blood.

Respiratory disorders

More than 40 conditions affect the lungs and/or airways, and respiratory disease causes one in five deaths in the UK. In addition:

  • Respiratory conditions are the single largest cause of certified work absence, with infections the most common reason.
  • Asthma is the most common long-term condition in children and young adults.
  • COPD is the only major cause of death that has increased significantly in recent years.
  • Lung cancer is the one of the most common forms of cancer in the UK and the most common cause of death from cancer.

NICE NG12. Suspected cancer: recognition and referral; 2015 (updated 2021)

British Lung Foundation. Lung conditions Information for patients.

Health and Safety Executive. Respiratory diseases (work-related, by employment sector)

Primary Care Respiratory Society UK (PCRS-UK)

British Thoracic Society


Variety of conditions causing gradually progressive shortness of breath and cough. Many different causes, but a common feature is deposition throughout the lungs of fibrous material that destroys lung tissue. Examples are: Dust-related diseases, e.g. Coal worker's pneumoconiosis, asbestosis Extrinsic allergic alveolitis (hypersensitivity pneumonitis), eg pigeon fancier’s lung, farmer’s lung Idiopathic pulmonary fibrosis (cryptogenic fibrosing alveolitis) Primary disease, e.g. sarcoidosis

BTS Guideline on Interstitial Lung Disease (DPLD), 2008

NICE CG163 Idiopathic pulmonary fibrosis, 2013

Practice Nurse featured article


Disease in which there is progressive multiplication of cells (neoplasia) under conditions where this would not normally occur. When a malignant tumour forms, its cells are invasive, lose their differentiation and orientation, and disperse to parts of the body distant from the initial growth (metastasise). Cancer’s natural course is fatal. In most cancers, early detection and treatment increases the chance of survival. Lung cancer is the second most common cancer in the UK, and by far the biggest cause is smoking, causing 8 out of 10 cases. The 2 main groups of primary lung cancer are: 

Small cell lung cancer – so called because under the microscope the cells appear small and mostly taken up by the nucleus. Accounts for 12% of lung cancers and very rare in people who have never smoked.

Non small cell lung cancer – includes squamous cell carcinoma, adenocarcinoma and large cell carcinoma.

Secondary lung cancer is frequently associated with breast or bowel cancer that has metastasised. Treatment depends on the where the cancer originated.

Cancer Research UK. About cancer

Macmillan Cancer Support. Cancer A to Z

NICE NG12. Suspected cancer: recognition and referral; 2015 (updated 2021)

Cancer treatments include surgery, radiotherapy and chemotherapy. Adverse effects of therapy include immunosuppression, and hence susceptibility to infection, and more specific problems such as sore mouth and eating problems with radiotherapy to the head and neck, and hair loss with chemotherapy. Patients will see specialist staff but may appreciate additional support and help with accessing resources.


Most common RTIs are self-limiting viral infections that clear up fairly quickly in previously well patients, needing only simple self-help advice or OTC remedies. Patients will not benefit from an antibiotic unless their symptoms are caused by bacterial rather than viral infection (clinical distinction is often not possible), or they are at risk of complications from the infection. URTIs cause considerable discomfort but rarely death or serious illness. LRTIs are usually more serious, and particularly common and serious in the elderly. Certain infections, such as influenza, can affect both the upper and lower respiratory tract.

NICE NG120.  Cough (acute): antimicrobial prescribing; 2019

Acute bronchitis

Inflammation of the bronchial tree. Common in winter; generally a complication of viral upper respiratory infection (common cold, sore throat or influenza). Presents with hacking cough, usually bringing up yellowy-grey mucus; may be pyrexia, retrosternal pain and wheeze, rhonchi, coarse crepitations.

Red flags

  • Haemoptysis
  • Acute breathlessness
  • Pleuritic chest pain
  • Obstruction of the airway

Practice Nurse featured article

Cough: not always what it seems Margaret Perry 

Common cold

A viral infection of the nose and throat, and the most common acute illness in the industrialised world. Adults generally have 2-4 colds per year, children up to 12. Young children are main reservoir of the causative viruses. Symptoms of the common cold syndrome are caused by >200 different viruses. Rhinoviruses (nose viruses) account for c. 30-50% of adult colds; others include coronavirus, respiratory syncytial virus (RSV), adenovirus, parainfluenza virus, influenza virus.


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Nasal congestion Dr Knut Schroeder, Sara Richards 

Croup (laryngotracheitis)

Infection of the larynx and trachea, with laryngeal oedema and obstruction of airway by thick, tenacious secretions. Presents with barking cough of sudden onset, usually inspiratory stridor, often hoarseness, respiratory distress. Usually affects children between 6 months and 3 years old


Highly contagious acute viral infection of the upper respiratory tract. Onset is sudden, symptoms include headache, myalgia, fever and cough. Spread is by droplet, person-to-person contact or contact with contaminated items, e.g. door handles. May predispose to secondary bacterial infection of the upper and lower respiratory tract. Most recover in 1–2 weeks without complications but ‘flu’ can cause serious illness and death, especially in very young, elderly or infirm. Influenza occurs most often in winter and usually peaks December–March in the northern hemisphere. Every 2–3 years epidemics occur, and mortality may be high.

Practice Nurse featured article

How viruses attack: the story and history of influenza Beverley Bostock-Cox  

Top tips for patients to help combat flu Sara Richards 


Inflammation of the larynx. Presents with hoarseness, loss of voice, sore throat.


Refer urgently patients with hoarseness persisting >3 weeks


Inflammatory infection of the bronchioles and alveoli.

Community-acquired pneumonia (CAP) occurs in 1 in 100 of the population each year, twice as common in winter, highest rates in elderly and young. About 10% is viral; most common bacterial causes are: Streptococcus pneumoniae (pneumococcus), Mycoplasma pneumoniae, Haemophilus influenzae. Infections with Legionella pneumophila are generally the result of droplet infection from an air-conditioning system.

NICE NG138. Pneumonia (community-acquired): antimicrobial prescribing; 2019 

Hospital-acquired pneumonia develops in up to 50% of patients, mortality rate is high. Organisms commonly identified are pneumococcus, Staphylococcus aureus, and Gram-negative bacteria (Pseudomonas, Klebsiella, Proteus).


Inflamed or infected sinuses. Often follows an acute viral URTI. Inflammation of mucous membranes of paranasal sinuses can result from inadequate drainage of sinuses secondary to infection, allergy or obstruction. May present with headache, pyrexia, localised pain (worse when bending forward) and tenderness over involved sinus. Complications, e.g. facial or periorbital cellulitis, are more common in children than in adults.

Sore throat/tonsillitis

Incidence peaks at 5-10 and 15-25 years. Spectrum includes laryngitis, pharyngitis and, in a few, tonsillitis; clinical distinction between the last two not always clear. Streptococcal tonsillitis more likely if patient is less than 11 years old, with myalgia, fever history, tonsillar exudates, tender or swollen cervical lymph glands, less likely if cough/earache present. If recurrent sore throat very troublesome, e.g. child often misses school, tonsillectomy may be indicated but is not undertaken lightly.

Snoring and obstructive sleep apnoea

Snoring is vibratory noise generated from the pharynx and soft palate during sleep. Apnoea is a temporary absence or cessation of breathing. Obstructive sleep apnoea (OSA) occurs when complete closure of the pharyngeal airway causes repeated episodes of apnoea and transient arousal. The result is fragmented sleep and excessive daytime sleepiness (test with Epworth scale - see Appendix), making it dangerous for those affected to drive or operate machinery. Causes include overweight (neck circumference >16in), nasal congestion, evening alcohol/sedatives, large tonsils, receding lower jaw. Patients diagnosed with OSA should be referred to a sleep unit or physician with a special interest in sleep problems. OSA may be improved by lifestyle changes such as weight loss, smoking cessation, changes in sleeping position and avoidance of alcohol or night sedation tablets. Continuous positive airway pressure (CPAP) is most commonly used for severe OSA.

NICE TA139 Continuous positive airway pressure (CPAP) for treatment of obstructive sleep apnoea/hypopnoea syndrome, 2008

NICE Guideline in development. Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome. Expected publication date: August 2021. Draft for consultation, March 2021.

Practice Nurse featured article 


Certain signs and symptoms are indicative of more serious respiratory disease

  • Haemoptysis
  • Acute breathlessness
  • Pleuritic chest pain
  • Obstruction of the airway
  • Fever >40oC
  • Respiratory rate >30/min
  • BP <90/60mmHg
  • Pleuritic chest pain or confusion indicates severe infection
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